Liquid crystal display device having rubber bushes for receiving ends of a fluorescent tube and enabling connection of lamp cables thereat

Abstract

Herein disclosed are a liquid crystal display device and a data processing device, which can have their frame portions reduced in area to reduce the size and weight by extracting the terminals of video signals to only one side of a liquid crystal display panel and by arranging a video signal line driving circuit substrate to be connected with the terminals, only at one side of the display panel. A liquid crystal display device includes a liquid crystal display panel, a light guide plate, a fluorescent tube, and a lamp reflector. first and second lamp cables of different length are connected to the fluorescent tube. One end of the fluorescent tube is inserted in a hole of a first rubber bush and a part of the one end of the fluorescent tube is connected to the first lamp cable in the hole of the first rubber bush and an other end of the fluorescent tube is inserted in a hole of a second rubber bush and a part of the other end of the fluorescent tube is connected to the second lamp cable in the hole of the second rubber bush.

Description

CROSS REFERENCE TO RELATED APPLICATION

wherein delta V1C indicates the variation of the central potential due to delta Vg. This variation delta V1c causes the DC component to be added to the liquid crystal LC and can be reduced the more for the higher additional capacitor Cadd. Moreover, the additional capacitor Cadd functions to elongate the discharge time and stores the video information for a long time after the thin film transistor TFT is turned off. The DC component to be applied to the liquid crystal LC can improve the lifetime of the liquid crystal LC, to reduce the so-called “printing”, by which the preceding image is left at the time of switching the liquid crystal display frame.

Since the gate electrode GT is enlarged to such an extent as to cover the semiconductor layer AS completely, as has been described hereinbefore, the overlapped area with the source electrode SD1 and the drain electrode SD2 is increased to cause an adverse effect that the parasitic capacity Cgs is increased to make the center potential V1c liable to be influenced by the gate (scanning) signal Vg. However, this demerit can be eliminated by providing the additional capacitor Cadd.

The latching capacity of the additional capacitor Cadd is set from the pixel writing characteristic to a level four to eight times as large as that of the liquid crystal capacity Cpix (4*Cpix<Cadd<8*Cpix) and eight to thirty two times as large as that of the capacity Cgs (8*Cgs<Cadd<32*Cgs).

<<Method of Connecting Electrode Line of Additional Capacitor Cadd>>

The initial stage scanning signal line GL (i.e., Y₀) to be used only as the capacity electrode line is set to the same potential as that of the common transparent pixel electrode (Vcom) ITO2, as shown in FIG. 12. In the example of FIG. 19, the initial stage scanning signal line is short-circuited to the common electrode COM through the terminal GTO, the leading line INT, a terminal DTO and an external line. Alternatively, the initial stage latching capacity electrode line Y₀ may be connected with the final stage scanning signal line Yend or a DC potential point (or AC ground point) other than the Vcom, or connect to receive one excess scanning pulse Y₀ from the vertical scanning circuit V.

<<Structure for Connection with External Circuit>>

FIG. 22 is a diagram showing a sectional structure of the tape carrier package TCP, in which the integrated circuit chip CHI is mounted on the flexible wiring substrate (as called “TAB”: Tape Automated Bonding), to construct the scanning signal driving circuit V or the video signal driving circuits He and Ho. FIG. 23 is a section showing the state of an essential portion, in which the tape carrier package TCP is connected in the present example with the video signal circuit terminal DTM.

In the same drawing, letters TTB designate an input terminal/wiring portion of the integrated circuit CHI, and letters TTM designate an output terminal/wiring portion of the integrated circuit CHI. These portions are made of Cu, for example, and have their individual inner leading end portions (as called the “inner leads”) connected with a bonding pad PAD of the integrated circuit CHI by the so-called “faced-down bonding method”. The terminals TTB and TTM have their outer leading end portion (as called the “outer leads”) corresponding to the input and output of the semiconductor integrated circuit chip CHI, respectively, and are connected with the CRT/TFT converter circuit and the power supply circuit SUP by the soldering method and with the liquid crystal display panel PNL through an anisotropic conductive film ACF. The package TCP is so connected with the panel that its leading end portion covers the passivation film PSV1 having the connection terminal DTM exposed at the side of the panel PNL. As a result, the external connection terminal DTM (GTM) is strong against the galvanic corrosion because it is covered with at least one of the passivation film PSV1 or the package TCP.

Letters BF1 designate a base film made of polyimide or the like, and letters SRS designate a solder resist film for masking to prevent the solder from leaking to an unnecessary portion at the soldering time. The gap between the upper and lower glass substrates outside of the seal pattern SL is protected after the rinsing step by the epoxy resin EPX or the like, and this protection is multiplexed by filling a silicone resin SIL between the package TCP and the upper substrate SUB2.

<<Manufacturing Process>>

Next, a process for manufacturing the side of the substrate SUB1 of the aforementioned liquid crystal display device will be described with reference to FIGS. 14 to 16. In these Figures, the central letters indicate the abbreviations of the step names, and the left hand sides show the pixel portions shown in FIG. 3 whereas the right hand sides show the process flow, as viewed in suction from the vicinity of the gate terminals shown in FIG. 10. Steps A to I excepting Step D are divided to correspond to the individual photolithographic steps, and any sections of the individual steps indicate the steps, at which the photo resists are removed after the photolithographic treatments. Incidentally, these photolithographic treatments are intended in the present description to imply a series of operations from the application of a photo resist to the development through a selective exposure using a mask, and their repeated description will be omitted. The description will be made in accordance with the steps divided, as follows.

Step A, FIG. 14(A)

A silicon dioxide film SIO is deposited by the dip treatment on both surfaces of a lower transparent glass substrate SUB1 made of 7059 glass (under the trade name), and then a baking is carried out at 500 degree for 60 minutes. A first conductive film g1 consisting of a 1,100 angstrom chromium film is deposited on the lower transparent glass substrate SUB1 by the sputtering. After the photolithographic treatment, the first conductive film g1 is etched selectively by the photoetching using a ceric ammonium nitrate solution as an etching solution, thereby forming a gate terminal GTM and a drain terminal DTM and forming also a power bus line SMg for anodization for connecting the gate terminal GTM, and a pad (although not shown) connected with the power bus line SHg for anodization.

Step B, FIG. 14(B)

A second conductive film g2 having a thickness of 2,800 angstroms and made of Al—Pd, Al—Si, Al—Si—Ti or Al—Si—Cu is formed by the sputtering. After the photolithographic treatment, the second conductive film g2 is selectively etched with a mixed acid solution of phosphoric acid, nitric acid and glacial acetic acid.

Step C, FIG. 14(C)

After the photolithographic treatment (i.e., after the formation of the aforementioned anodized mask AO), the substrate SUB1 is dipped in the anodizing liquid which is prepared by diluting a solution containing 3% of tartaric acid adjusted to PH 6.2 to 6.3 with a solution of ethylene glycol, and the anodizing current density is adjusted to 0.5 mA/cm² (for anodization at a constant current). Next, an anodization is carried out till an anodization current of 125 V necessary for a predetermined Al₂O₃ film thickness is reached. After this, the substrate SUB1 is desirably held in this state for several ten minutes (for anodization at a constant voltage). This is important for achieving a uniform Al₂O₃ film. Thus, the conductive film g2 is anodized to form an anodized film AOF having a thickness of 1,800 angstroms over the scanning signal line GL, the gate electrode GT and the electrode PL1.

Step D, FIG. 15(A)

Ammonia gas, silane gas and nitrogen gas are introduced into a plasma CVD apparatus to form a Si nitride film having a thickness of 2,000 angstroms, and silane gas and hydrogen gas are introduced into the plasma CVD apparatus to form an i-type amorphous Si film having a thickness of 2,000 angstroms. After this, hydrogen gas and phosphine gas are introduced into the plasma CVD apparatus to form an N(+)-type amorphous Si film having a thickness of 300 angstroms.

Step E, FIG. 15(B)

After the photolithography, the N(+)-type amorphous Si film and the i-type amorphous Si film are selectively etched by the photoetching using SF₆ and CCl₄ as the dry etching gas to form an island of an i-type semiconductor layer AS.

Step F, FIG. 15(C)

After the photolithography, the Si nitride film is selectively etched by using SF₆ as the dry etching gas.

Step G, FIG. 16(A)

A first conductive film d1 formed of an ITO film having a thickness of 1,400 angstroms is formed by the sputtering. After the photolithography, the first conductive film d1 is selectively etched by using a mixed acid solution of hydrochloric acid and nitric acid as the etching solution, to form the uppermost layer of the gate electrode GTM and the drain terminal DTM and the transparent pixel electrode ITO1.

Step H, FIG. 16(B)

A second conductive film d2 of Cr having a thickness of 600 angstroms is formed by the sputtering, and a third conductive film d3 of Al—Pd, Al—Si, Al—Si—Ti or Al—Si—Cu having a thickness of 4,000 angstroms is formed by the sputtering. After the photolithography, the third conductive film d3 is etched by a solution similar to that of Step B, and the second conductive film d2 is etched by a solution similar to that of Step A, to form the video signal line DL, the source electrode SD1 and the drain electrode SD2. Next, CCl₄ and SF₆ are introduced into a dry etching apparatus to etch the N(+)-type amorphous Si film thereby to remove the N(+)-type semiconductor layer d0 selectively from between the source and the drain.

Step I, FIG. 16(C)

Ammonia gas, silane gas and nitrogen gas are introduced into a plasma CVD apparatus to form a Si nitride film having a thickness of 1 micron. After the photolithography, the Si nitride film is selected by the photoetching technique using SF₆ as the dry etching gas, to form the passivation film PSV1. <<Structure of Whole Liquid Crystal Display Module>>

FIG. 1 is an exploded perspective view showing a liquid crystal display module MDL, and the specific construction of the individual components is shown in FIGS. 24 to 45.

Letters SHD designate a shield casing (which may also be called the “metal frame”) made of a metal plate; letters WD a display window; letters INS1 to INS3 designate insulating sheets; letters PCB1 to PCB3 designate circuit substrates (composed of a drain side circuit substrate PCB1, a gate side circuit substrate PCB2, and an interface circuit substrate PCB3); letters JN designate a joiner for electrically connecting the circuit substrates PCB1 to PCB3 with each other; letters TCP1 and TCP2 designate tape carrier packages; letters PNL a liquid crystal display panel; letters GC designate a rubber cushion; letters ILS designate a shade spacer ILS; letters PRS designate a prism sheet; letters SPS designate a diffusion sheet; letters GLB designate a light guide plate; letters RFS designate a reflecting sheet; letters MCA designate a lower casing (or mold casing) formed by the monolithic molding letters LP designate a fluorescent tube; letters LPC designate a lamp cable; and letters GB designate a rubber bush supporting the fluorescent tube LP; and letters BAT designate double sided adhesive tape. These members are individually stacked in the following arrangement relation, as shown, to assemble a liquid crystal display module MDL.

The module MDL has two kinds of accommodating and holding members of a lower casing MCA and a shield casing SHD. The module MDL is assembled by uniting the metallic shield casing SHD, which accommodates and fixes the insulating sheets INS1 to INS3, the circuit substrates PCB1 to PCB3 and the liquid crystal display panel PNL, and the lower casing MCA, which accommodates a back light BL composed of the fluorescent tube LP, the optical guide plate GLB and the prism sheet PRS.

Here will be described those individual members in detail in the following.

<<Metallic Shield Casing SHD>>

FIGS. 25(A)-25(D) present the upper side, front side, rear side, right hand side and left hand side of the shield casing SHD, and a perspective view, as taken obliquely from above the shield casing SHD.

The shield casing (or metal frame) SHD is fabricated by punching or folding a metal sheet by the pressing technique. Letters WD designate a window for exposing the display panel PNL to the field of view, as will be called the “display window”.

Letters NL designate fixing pawls (totally twelve in number) for fixing the shield casing SHD and the lower casing MCA, and letters HK also designate fixing hooks (totally four in number) integrally formed in the shield casing SHD. Before the fixing pawls NL shown in FIGS. 1 and 25 are folded, the circuit substrates PCB1 to PCB3 are accommodated in the shield casing SHD. After this, the fixing pawls NL are folded inward and inserted into the rectangular fixing recesses NR (as shown at the individual side elevation of FIG. 37) which are formed in the lower casing MCA. The fixing hooks HK are individually fitted on the fixing projections HP (as shown at the side elevation of FIG. 37) formed in the lower casing MCA. As a result, the shield casing SHD holding and accommodating the circuit substrates PCB1 to PCB3, and the lower casing MCA holding and accommodating the light guide plate GLB and the fluorescent tube LP are firmly fixed. On the other hand, such four sides of the lower side of the display panel PNL, as will exerts no influence upon the display, have their edges equipped with the thin and long rubber cushion GC (which may also be called the “rubber spacer”, as shown in FIGS. 1 and 43) having a rectangular shape. This rubber cushion GC is sandwiched between the display panel PNL and the light guide plate GLB. By pushing the shield casing SHD into the device by making use of the elasticity of the rubber cushion GC, the fixing hooks HK are caught by the fixing projections HP, and the fixing pawls NL are folded into the fixing recesses NR. As a result, those individual fixing members function as stoppers to fix the shield casing SHD and the lower casing MCA so that the module is firmly held in its entirety while requiring no other fixing members. Thus, the assembly can be facilitated to reduce the production cost. Moreover, the mechanical strength can be increased to enhance the vibration and impact resistances thereby to improve the reliability of the device. Since, on the other hand, the fixing pawls NL and the fixing hooks HK can be easily removed (merely by straightening the fixing pawls NL and removing the fixing hooks HK), these two members can be easily disassembled and assembled so that they can be easily repaired to facilitate the replacement of the fluorescent tube LP of the back light BL. In the present embodiment, moreover, one side is fixed mainly by the fixing hooks HK whereas the opposed other side is fixed by the fixing pawls NL, as shown in FIG. 25, so that the disassembly can be effected merely by removing not all but some of the fixing pawls NL. As a result, the repair and the replacement of the back light can be facilitated.

Letters CH designate common through holes which are formed in common plan positions shared among the circuit substrates PCB1 to PCB3. At the manufacturing time, the shield casing SHD and the circuit substrates PCB1 to PCB3 are sequentially packaged by fitted the individual common through holes CH on fixed upright pins, so that they may be accurately positioned relative to each other. Moreover, the common through holes CH can be used as positioning references when the module MDL is to be packaged in an appliance such as a personal computer.

Letters FGN designate totally twelve frame ground pawls formed integrally with the metallic shield casing SHD. These frame ground pawls FGN are constructed of rectangular projections extending into square openings, i.e., the C-shaped openings which are formed in the side of the shield casing SHD. These slim projections, i.e., the pawls FGN are individually folded at their roots inward of the device and are soldered and connected to the frame ground pads FGP (as shown in FIGS. 24 and 27) which are connected with the (now- shown) ground wiring lines of the circuit substrates PCB1 to PCB3. Incidentally, since the pawls FGN are formed on the side of the shield casing SHD, the works of folding the pawls FGN into the device and soldering the same to the frame ground pads FGP can be effected with the shield casing SHD having its inner side (or lower side) being directed upward, after the circuit substrates PCB1 to PCB3 integrated with the liquid crystal display panel PNL have been accommodated in the shield casing SHD, so that the workability is satisfactory. Moreover, the pawls FGN are free, when folded, from abutment against the circuit substrates PCB1 to PCB3, so that the folding works are satisfactory. In the soldering works, moreover, the soldering iron can be applied from the inner side of the opened shield casing SHD so that the soldering works are satisfactory. As a result, the reliability of the connections between the pawls FGN and the frame ground pads FGP can be improved.

Letters SH1 to SH4 designate four mounting holes which are formed in the shield casing SHD so as to the module MDL as a display unit in a data processing device such as a personal computer or word processor. The lower casing MCA is also formed with mounting holes MH1 to MH4 which are aligned with the mounting holes SH1 to SH4 of the shield casing SHD (as shown in FIGS. 37 and 38), and screws are threaded into the two mounting holes to fix and package the data processing device. Incidentally, in case the mounting holes are to be formed in the corners of the metallic shield casing SHD, the drawn portions (i.e., the drawn portions which are integral with a metal plate forming the metallic shield casing SHD and which form a parallel plane at a level different from that of the metal plate) of the mounting holes can be formed into a quadrant shape. In case, however, the mounting holes SH are intended to be formed not in the corners but in intermediate portions at a predetermined distance from the corners from the standpoints of both the arrangement of the packaged parts of the circuit substrate PCB3 and the electric connection between the circuit substrates PCB1 and PCB2, the shape of the drawn portions DR of the mounting holes SHD cannot be the quadrant shape but a semicircular shape from the conveniences of the drawing operation so that the areas necessary for the mounting holes are enlarged. As shown in FIG. 25, therefore, notches L are formed in the radial portions of the quadrant shapes between the drawn portions DR and the adjoining metal plate to facilitate the drawing operation so that the drawn portions DR of the mounting holes SH1 can be formed into the quadrant shape to reduce the areas necessary therefor. As a result, the module MDL can be small- sized and light-weighted to reduce the production cost. In other words, the mounting holes SH can be formed at the intermediate portions at the predetermined distance from the corners of the module MDL while realizing the size reduction of the module MDL.

<<Circuit Substrates PCB1 to PCB3>>

FIG. 26 presents the lower side and respective sections showing the state in which the circuit substrates PCB1 to PCB3 are packaged in the outer peripheral portions of the display panel PNL; FIG. 24 presents the lower side and individual sections showing the state in which the display panel PNL and the circuit substrates PCB1 to PCB3 are accommodated and packaged in the shield casing SHD; FIG. 27 presents the lower sides of the circuit substrates PCB1 to PCB3 (showing that the tape carrier package TCP is not packaged in the circuit substrates PCB1 and PCB2 but the circuit substrate PCB3 in more detail than FIGS. 24 and 26); FIG. 29(A) presents the lower side of the circuit substrate PCB3 in the state having no electric parts packaged; FIG. 29(B) presents the lower side showing the same in the state having the electric parts packaged; FIG. 31 presents the lower side of the circuit substrate PCB1 (not having the tape carrier package TCP packaged); and FIG. 32 presents the lower side of the circuit substrate PCB2 (not having the tape carrier package TCP packaged).

Letters CHI1 and CHI2 designate the drive IC (i.e., integrated circuit) chips (of which the lower five of FIG. 26 are drive IC chips at the vertical scanning circuit side whereas the left hand ten are drive IC chips at the video signal drive circuit side) for driving the display panel PNL. Letters TCP1 and TCP2 designate the tape carrier packages in which the driving IC chip CHI is packaged by the tape automated bonding (i.e., TAB) method, as described with reference to FIG. 23, and letters PCB1 and PCB2 designate circuit substrates which are made of the PCB (i.e., printed circuit board) individually having the TCP, a capacitor CDS and so on packaged therein. Letters FGP designate a frame ground pad; letters JN3 designate a joiner for electrically connecting the drain side circuit substrate PCB1 and the gate side circuit substrate PCB2; and letters JN1 and JN2 designate joiners for electrically connecting the drain side circuit substrate PCB1 and the interface circuit substrate PCB3. The joiners JN1 to JN3, as shown in FIG. 35, are constructed by sandwiching and supporting a plurality of lead wires (made of a phosphor bronze material plated with Sn) between a striped polyethylene layer and a polyvinyl alcohol layer. Incidentally, the JN1 to JN3 can also be constructed by using an FPC (i.e., flexible printed circuit).

Specifically, the display panel PNL has its three outer peripheral portions arranged with the circuit substrates PCB1 to PCB3 of the display panel PNL in the shape of letter “C”. The outer peripheral portion of one longer side (as located at the left hand side of FIG. 24) of the display panel PNL is arranged with the drain side circuit substrate PCB1 in which there are packaged a plurality of tape carrier packages TCP1 each having the drive IC chip (or driver) CHI1 mounted for feeding the drive signals to the video signal lines (i.e., drain signal lines) of the display panel PNL. On the other hand, the outer peripheral portion of one shorter side (as located at the lower side of FIG. 24) of the display panel PNL is arranged with the gate side circuit substrate PCB2 in which there are packaged a plurality of tape carrier packages TCP2 each having the drive IC chip CHI2 mounted for feeding the drive signals to the scanning signal lines (i.e., gate signal lines) of the display panel PNL. Moreover, the outer peripheral portion of the other shorter side (as located at the upper side of FIG. 24) of the display panel PNL is arranged with the interface circuit substrate (which may also be called the “control circuit substrate” or “converter circuit substrate”) PCB3.

Since the circuit substrates PCB1 to PCB3 are divided into three generally rectangular shapes, the stresses to be established in the directions of their longer axes due to the difference in the coefficients of thermal expansion between the display panel PNL and the circuit substrates PCB1 to PCB3 are absorbed at the portions of the joiners JN1 to JN3. As a result, the separations between the output leads (i.e., TTM of FIGS. 22 and 23) of the tape carrier package TCP having a low connection strength and the external terminals (i.e., DTM (or GTM) of FIGS. 22 and 23) of the liquid crystal display panel PNL can be prevented, and the stress of the input leads of the tape carrier package TCP can be damped to improve the reliability of the module against the heat. Since such substrates are given a simpler rectangular shape than the C-shape of the substrate, the numerous sheets of circuit substrates PCB1 to PCB3 can be made of a single sheet of substrate material so that the using percentage of the printed substrate material can be increased to effectively reduce the cost for the parts/materials (e.g., to about 50% in the case of the present embodiment). Incidentally, if the circuit substrates PCB1 to PCB3 are made of a soft FPC (i.e., flexible printed circuit) in place of the PCB (i.e., printed circuit board) made of a glass epoxy resin, the FPC can warp to further enhance the lead separation preventing effect. Moreover, an integral C-shaped PCB can also be used. Then, there are achieved effects that the management of the manufacturing steps can be simplified by reducing the step number and the parts number, and that the reliability can be improved by abolishing the joiners between the circuit substrates.

The frame ground pads FGP, as connected to the individual ground wiring lines of the three circuit substrates PCB1 to PCB3, are provided, five, four and three, that is, totally twelve in number, as shown in FIG. 27. In case the circuit substrate is divided into a plurality, no electric problem will arise if at least one of the drive circuit substrates is connected with the frame ground in the DC manner. If the number of the drive circuit substrates is small in the higher frequency range, a potential for establishing the unnecessary radiative electric waves for causing the EMI (i.e., electromagnetic interference) is raised by the causes of the reflections of electric signals and the deflections of the potentials of the ground wiring lines due to the difference in the characteristic impedances of the individual drive circuit substrates. The counter-measures for that EMI are difficult especially in the module MDL of the active matrix type using thin film transistors. In order to prevent this, for each of a plurality of divided circuit substrates, the ground wiring lines (at the AC grounded potential) are connected with the common frame (i.e., the shield casing SHD) having a sufficiently low impedance. As a result, the ground wiring lines are strengthened in the higher frequency range, the electric field intensity is improved by 5 dB or more in the case of the twelve pads of the present embodiment, as compared with the case in which only one is connected with the shield casing SHD as a whole.

The frame grounding pawls FGN of the shield casing SHD are formed of the slender metal projections, as described, and can be connected to the frame ground pads FGP of the circuit substrates PCB1 to PCB3 by folding them, while requiring no special wires (or lead wires) for the connections. Moreover, the shield casing SHD and the circuit substrates PCB1 to PCB3 can be mechanically connected through the pawls FGN to improve the mechanical strengths of the circuit substrates PCB1 to PCB3.

In order to suppress the emission of the unnecessary radiative electric waves to cause the EMI, a plurality of resistors/capacitors for smoothing the signal wave forms are discretely arranged in the prior art in the vicinity of the signal source integrated circuit or in the course of the signal transmission route. As a result, there are required several spaces for interposing the resistors/capacitors in the vicinity of the signal source integrated circuit and between the taper carrier packages, so that the dead spaces are so enlarged that the electronic parts cannot be packaged in a high density. In the present embodiment, as shown in FIG. 24, the plurality of capacitors/resistors CR for the EMI are concentratedly arranged at the end portion of the drain side circuit substrate PCB1 downstream of the signals of the plurality of drive IC chips CHI1, far from the signal source integrated circuit TCON (as will be described in detail hereinafter) mounted in the interface circuit substrate PCB3, and farther from the drive IC chip CHI1 of the drain side circuit substrate PCB1 for receiving the signals from the signal source integrated circuit TCON. As compared with the discrete arrangement, therefore, the dead spaces can be reduced to package the electronic parts highly densely. As a result, the module MD can be small-sized and light- weighted to reduce the production cost.

<<Drain Side Circuit Substrate PCB1>>

One sheet of drain side circuit substrate PCB1 is arranged only at one longer side (i.e., at the left hand side of FIG. 24) of the display panel PNL, as shown in FIG. 24. Specifically, the video signal lines DL have their terminals extracted like the scanning signal lines GL at only one side of the liquid crystal display panel PNL. As a result, the area of the periphery of the display unit, i.e., the so-called “frame portion” can be reduced, as compared with the construction in which the video signal lines are alternately extracted to the two opposed longer sides of the display panel PNL and in which the drain side circuit substrates are individually arranged outside of the individual longer sides. As a result, the external size of the liquid crystal display module MDL and the data processing device (as shown in FIG. 47) such as a personal computer or word processor having the liquid crystal display module MDL assembled as the display unit can be reduced to reduce the weight. As a result, the material can be decreased to reduce the production cost. Incidentally, the drain side circuit substrate PCB1 is arranged at the side which is located at the upper side of the display, as shown in FIG. 47, when the module MDL is packaged in the personal computer or word processor. For this, a notebook type personal computer or word processor is required usually at the lower portion of the display to have the space for providing hinges to attach the display unit to the keyboard portion, so that the vertical positioning of the display can be made proper by arranging the drain side circuit substrate in the upper portion of the display. Incidentally, in FIG. 31: letters JP11 designate pads to be connected with the joiner JN1; letters JP12 designates pads to be connected with the joiner JN2; and letters JP13 designate pads to be connected with the joiner JN3.

In the module of the prior art, in which the video signal lines are alternately extracted to the upper and lower portions of the liquid crystal display panel and in which the two drain side circuit substrates are arranged at the upper and lower sides of the outer periphery of the liquid crystal display panel, the electronic parts are arranged along the flow of the signals which come from the external personal computer of the like into that module. Thus, there are arranged at the central portion of the interface circuit substrate with the connector to be connected with the personal computer or the like and the signal source integrated circuit TCON. In case the drain side circuit substrate PCB1 is arranged at one side of the liquid crystal display panel PNL, as in the present embodiment, the following layout is taken, if the arrangement of the electronic parts along the signal flow is taken as in the prior art. Specifically, the connector CT is arranged in the end portion closest to the corner of the shield casing SHD (as shown in FIG. 24, but not in the corner of the shield casing SHD in the present embodiment), and the signal source integrated circuit TCON is arranged adjacent in the direction apart from that corner. If the connector circuit CT is to be arranged at the remotest end of the circuit substrate PCB3, i.e., in the corner of the shield casing SHD, it cannot be covered with the lower casing MCA because it is connected with the personal computer (because the notches MLC of the lower casing MCA are positioned above the connector CT, as shown in FIG. 37). As a result, the corner of the shield casing SHD having the mounting holes SH4 cannot be covered with the lower casing MCA having the aligned mounting holes MH5. In the present embodiment, therefore, the signal source integrated circuit TCON, as at a lower level, is arranged at the remotest end of the circuit substrate PCB 3, i.e., over the circuit substrate PCB 3 in the vicinity of the corner of the shield casing SHD, and the vicinity of the corner can be covered with the lower casing MCA whereas the connector CT is arranged adjacent in the direction apart from that corner. Specifically, the vicinity of the corner of the shield casing SHD having the mounting hole SH4 is covered with the lower casing MCA having the aligned mounting hole MH4. As a result, when the module MDL is packaged in the data processing device such as the personal computer, the shield casing SHD and the lower casing MCA of the module MDL have their corners firmly held and fixed by screws or the like through their mounting holes SH4 and MH4 so that the mechanical strength is improved to improve the reliability of the product. Incidentally, as shown in FIG. 47, the signals coming from the personal computer or the like flow at first from the connector CT once to the signal source integrated circuit TCON and then to the drive IC chip CHI1 of the drain side circuit substrate PCB1. As a result, the signal flow is regulated to eliminate any useless signal flow so that the useless wiring lines can be reduced to reduce the area of the circuit substrate.

In the embodiment shown in FIG. 24, moreover, the signal source integrated circuit TCON and the connector CT are disposed on the interface circuit substrate PCB3 at the opposite side of the connection side (i.e., at the side of the joiners JN1 and JN2) with the drain side circuit substrate PCB1. As a result, as shown in FIG. 47, the liquid crystal display module MDL is packaged in the personal computer, the word processor or the like such that its side having the drain circuit substrate PCB1 is opposed to the hinges, so that the connection cables with the host can be shortened. As a result, it is possible to reduce the noise which might invade from the connection cables between the host and the liquid crystal display module MDL. Moreover, the connection between the host and the signal source integrated circuit TCON can be most shortened to strengthen the resistance to the invention of the noise and the smoothing delay of the wave forms.

<<Gate Side Circuit Substrate PCB2>>

FIG. 32 is a top plan (or lower side) view of the circuit substrate PCB2. Letters JP23 designate a pad to be connected with the joiner JN3.

<<Tape Carrier Package TCP>>

FIG. 33 is a top plan (or lower side) view of the tape carrier package TCP on which is mounted the integrated circuit chip CHI.

The structure of the tape carrier package TCP and the connection structure with the liquid crystal display panel PNL have already been described in <<Connection Structure with External Circuit>> with reference to FIGS. 22 and 23 presenting the sections.

The planar shape of the package TCP is shown in FIG. 33. The reason why the terminal portions TM and TB have small contour widths is to cope with the narrowing of the terminal pitch. Specifically, the output terminal portion TM to be connected with the display panel PNL has its size adjusted to the pitch of the input terminals of the panel PNL, and the input terminal portion TB to be connected with the circuit substrate PCB1 to PCB2 has its size adjusted to the pitch of the output terminals of the circuit substrate PCB1 or PCB2.

Incidentally, either the output terminal portion TM or the input terminal portion TB may have its width made smaller than the outermost width.

FIG. 34 presents the top plan (or lower side) and side elevation showing the behavior in which a plurality of sheets of tape carrier packages TCP are packaged on the circuit substrates PCB1 and PCB2.

<<Interface Circuit Substrate PCB3>>

FIG. 29(A) presents the upper side of the interface circuit substrate PCB3 (i.e., having the connector CT and the hybrid integrated circuit HI packaged therein), and FIG. 29(B) presents the upper side having the signal source integrated circuit TCON and the parts such as the IC, capacitors or resistors packaged therein (and the connector CT and the hybrid integrated circuit HI in the portions, as indicated by dotted lines). On the interface circuit substrate PCB3, there are mounted not only the electronic parts such as the IC, capacitors or resistors but also: a power source circuit for achieving a plurality of stabilized voltage sources from one voltage source; and a circuit for transforming the data for the CRT (i.e., cathode ray tube) coming from the host (i.e., host processor) into the data for the TFT liquid crystal display device (as shown in FIG. 12). Letters CT designate a connector to be connected with the data processor such as the personal computer having that module MD packaged therein, and letters TCON designate a signal source integrated circuit for processing the image data sent from the host to transform them into the liquid crystal driving signals and for generating timing pulses to drive/control the gate side circuit substrate PCB2 and the drain side circuit substrate PCB1 thereby to display the data in the liquid crystal display device. Letters JP31 designate a connection portion to be connected with the joiner JN1, and letters JP32 designate a connection portion to be connected with the joiner JN2.

<<Electric Connections between Circuit Substrates PCB1 to PCB3>>

FIG. 36 presents the top plan and side elevation showing the state in which there are packaged in two stages the joiners JN1 and JN2 for electrically connecting the drain side circuit substrate PCB1 and the interface circuit substrate PCB3.

In accordance with development of recent years in the multiple colors of the color liquid crystal display device, the number of video signal lines for designating the gradations of red, green and blue colors increases together with the number of gradation voltages to that the portion having the function of the interface between that module and the setting side of the personal computer or the like to be assembled with that module is so complicated as to make difficult the electric connections between the drain side circuit substrate and the interface circuit substrate. Moreover, not only the number of video signal lines but also the number of connection lines are increased in accordance with the abrupt increase in the number of colors of the liquid crystal display device, because the connection lines effect the connections of the gradation voltages increasing in proportion to the color number, the clock and the power supply voltage.

At the corner of the shield casing SHD in which the two drain side circuit substrate PCB1 and interface circuit substrate PCB3 are adjacent to each other, as shown in FIG. 24, the individual connection lines are extracted to the individual adjoining end portions of the circuit substrate PCB1 and the circuit substrate PCB3, and the numeral terminals arrayed in two rows and in four columns are electrically connected by using the two joiners JN1 and JN2 which are arranged in two stages in the thickness direction of the circuit substrates. For thus connecting the circuit substrates, the space in the thickness direction of the module MDL is effectively exploited. By using the multistage joiners, the connection terminals can be connected in the small space even if their terminal number is large. As a result, the module MDL can be small-sized and light-weighted to reduce the production cost. In FIG. 36: letters JT1 designate the terminals of the joiner JN1; letters JT2 designate the terminals of the joiner JN2; letters PT1 designate the connection terminals of the circuit substrate PCB1; and letters PT3 designate the connection terminals of the circuit substrate PCB3.

Incidentally, the stage number of joiners should not be limited to two but can be three or more. Moreover, the electric connections between the drain side circuit substrate PCB1 and the gate side circuit substrate PCB2 are effected by using one joiner JN3 (as shown in FIG. 1) but may use a plurality of joiners stacked in multiple stages.

The mounting holes of the module MDL are usually arranged in the corners of the module MDL. When, however, the circuit substrates PCB1 and PCB3 are to be electrically disconnected by using the joiners JN, one circuit substrate PCB3 takes not the rectangular shape, as shown in FIG. 46, but a special shape having a protrusion. This special shape deteriorates the parting efficiency of the circuit substrate to raise the cost for the material of the circuit substrate. In the present embodiment, therefore, the mounting holes SH1 and SH2 of the shield casing SHD (and accordingly the mounting holes MH1 and MH2 of the lower casing MCA) are displaced from the corners of the module MDL or the shield casing SHD, as shown in FIG. 24. As a result, the space for connecting the joiners JN can be retained while leaving the circuit substrates PCB1, PCB2 and PCB3 generally rectangular (although the circuit substrate PCB3 is formed with the notch for the mounting hole SH1), so that the parting efficiency of the circuit substrate can be improved to reduce the cost for the material of the circuit substrate.

<<Hybrid Integrated Circuit HI and Electronic Parts EP Packaged in Two Stages on Interface Circuit Substrate PCB3>>

FIG. 30 presents the side elevation and front elevation of the hybrid integrated circuit HI mounted on the interface circuit substrate PCB3.

The hybrid integrated circuit HI, as shown in FIG. 24, is constructed by hybridly integrating its portion and by packaging a plurality of integrated circuits and electronic parts on the upper and lower sides of a small circuit substrate, and is packaged on the interface circuit substrate PCB3. As shown in FIG. 30, the leads HL of the hybrid integrated circuit HI are elongated to package a plurality of electronic parts EP on the circuit substrate PCB3 between the circuit substrate PCB3 and the hybrid integrated circuit HI. In case the number of parts is large, according to the prior art, the circuit substrates having the parts packaged therein are stacked in multiple stages and are connected by means of the joiners. As compared with this prior art, according to the present embodiment, the number of electronic parts can be reduced by the hybrid integration. Moreover, neither additional circuit substrate nor additional joiner is required (because the leads HL of the hybrid integrated circuit HI correspond to the joiners) so that the cost for the material and the number of working steps can be reduced. As a result, the production cost can be reduced while improving the reliability of the product.

<<Insulating Sheet INS>>

Between the metallic shield casing SHD and the circuit substrates PCB1 to PCB3, there are arranged the insulating sheets INS1 to INS3, as shown in FIG. 28, for insulating the two. Letters LT designate a double faced adhesive tape for bonding the insulating sheets INS1 to INS3 and the liquid crystal display panel PNL, and letters ST designate a double sided adhesive tape for bonding the insulating sheets INS1 to INS3 and the shield casing SHD.

<<Lower Casing MCA>>

FIG. 37 presents the top plan, upper side, rear side, right hand side and left hand side of the lower casing MCA, and FIG. 38 presents the lower side of the lower casing MCA.

The lower casing MCA, as molded, is a back light accommodating casing, i.e., a holding member for the fluorescent tube LP, the lamp cable LPC, the light conductive plate GLB and so on, and is monolithically molded of a synthetic resin by one mold. As has been described in detail in <Shield Casing SHD<>>, the lower casing MCA is firmly united with the metallic shield casing SHD by the actions of the individual fixing members and elastic members so that the module MDL can have its vibratory impulse resistance and thermal impulse resistances improved to improve the reliability.

The lower casing MCA is formed, in its bottom face at the central portion excepting the peripheral frame portion, with a large opening MO occupying a half or more area of the bottom face. As a result, after the module MDL has been assembled, the lower casing MCA can be prevented, by the repulsive force of the rubber cushion GC (of FIG. 42) between the liquid crystal display panel PNL and the light guide plate, from having its bottom face bulged by the vertical force applied downward to the bottom face of the lower casing MCA, thereby to suppress the maximum thickness. This makes it unnecessary to increase the thickness of the lower casing so as to suppress the bulging, so that the lower casing can be made thin to reduce the thickness and weight of the module MDL.

Letters MLC designate a notch (includes the notch for connecting the connector CT, as shown in FIG. 27), which is so formed in the lower casing MCA as to correspond to the exothermic parts of the interface circuit substrate PCB3, i.e., a packaged portion such as the hybrid IC power source circuit (e.g., a DC-DC converter) in the present embodiment. Thus, the heat liberation of the exothermic portions of the interface circuit substrate PCB3 can be improved not by covering the exothermic portion of the circuit substrate PCB3 with the lower casing MCA but by forming that notch. Specifically, at present, the multiple gradations and the single power source are demanded for improving the performance and the facility of the liquid crystal display device using the thin film transistors TFT. The circuit for realizing these demands consumes a high power. If the circuit means is to be packaged in compact, the packaging becomes so highly dense to raise the problem of the heat generation. As a result, the dense packaging and the compactness of the circuit can be improved by forming the lower casing MCA with the notch MLC corresponding to the exothermic portions. On the other hand, the signal source integrated circuit TCON is also considered as the exothermic parts, above which the lower casing MCA may be notched.

Letters MH1 to MH4 designate four mounting holes for mounting that module MD in the appliance such as a personal computer. The metallic shield casing SHD is also formed with the mounting holes SH1 to SH4 aligned with the mounting holes MH1 to MH4 of the lower casing MCA, so that it can be fixed and packaged in the appliance.

<<Back Light>>

FIG. 40(A) is a top plan view of an essential portion of the fluorescent tube LP, lamp cables LPC1 and LPC2 and rubber bushes GB1 and GB2 of the back light BL, FIG. 40(B) is a section taken along line B—B of FIG. 40(A) and FIG. 40(C) is a section taken along line C—C of FIG. 40(A).

The back light BL for supplying the light to the display panel PNL is composed of: the cold-cathode fluorescent tube LP; the lamp cables LPC1 and LPC2 of the fluorescent tube LP; the rubber bushes GB1 and GB2 for holding the fluorescent tube LP and the lamp cables LPC; the light guide plate GLB; the diffusive sheet SPS arranged in contact with the whole upper surface of the light guide plate GLB; the reflective sheet RFS arranged all over the whole lower surface of the light guide plate GLB; and the prism sheet PRS arranged in contact with the whole upper surfaces of the diffusion sheet SPS.

In the module MLD, the slender fluorescent tube LP is arranged in the space below the drain side circuit substrate PCB1 and the tape carrier package TCP1, which are packaged in one longer side of the liquid crystal display panel PNL. As a result, the module MDL can have its external size reduced so that it can be small-sized and light-weighted to reduce the production cost.

The rubber bushes GB1 and GB2 hold both the single cold-cathode fluorescent tube LP and the lamp cables LPC1 and LPC2. Specifically, the fluorescent tube LP is held in a larger-diameter hole HL Of the hole (having a shape of a key hole joining the larger-diameter hole and a smaller-diameter hole, as shown in FIG. 40(B)), which is formed in the rubber bushes GB1 and GB2. The lamp cable LPC1, as connected with one end of the fluorescent tube LP, is inserted and held in the groove GBD formed in the rubber bush GB2. Moreover, the lamp cable LPC2, as extracted in the same direction as that of the lamp cable LPC1, is inserted and held in the smaller-diameter hole H_s of the hole GBH of the rubber bush GB2 at the cable extraction side. Incidentally, the main portion of the hole GBH does not extend through the rubber bushes GB1 and GB2, but at least the rubber bush GB2 at the cable extraction side is formed with a smaller-diameter through hole which has communication with the smaller hole H_s of the hole GBH so as to extract the lamp cable LPC2 from the rubber bush GB2. When the two lamp cables are to be extracted in one direction with that construction, according to the prior art, there is no space for threading the lamp cables, and the lamp cables are not threaded through the rubber bushes, so that the lamp cables bulge out of the module. According to the present embodiment, however, the lamp cable LPC1 does not bulge out of the lower casing MCA so that the module MDL can have its space reduced. As a result, the module MDL can be small-sized and light-weighted to reduce the production cost. Since, moreover, both the fluorescent tube LP and the lamp cables LPC are held by the rubber bushes GB1 and GB2, these rubber bushes GB1 and GB2 holding the fluorescent tube LP are held by the holding forces of the lamp cables LPC so that the holdability of the fluorescent tube LP can be improved. Incidentally, the rubber bush GB1 holds the fluorescent tube LP and one lamp cable LPC1, and the rubber bush GB2 holds the fluorescent tube LP and the two lamp cables LPC1 and LPC2. In order to reduce the kinds of parts, however, the rubber bush GB1 used is given a shape similar to that of the rubber bush GB2.

Incidentally, the holes or grooves, which are formed in the rubber bushes GB1 and GB2 for holding the fluorescent tube LP and the lamp cables LPC, should not have their shapes limited to the shown ones. For example, the holes or grooves for holding the fluorescent tube LP and the two lamp cables LPC may be made independent, or the holes or grooves of the fluorescent tube LP and one or two lamp cables LPC may be suitably shared. Moreover, the rubber bush GB1 and the rubber bush GB2 used may have different shapes such that the rubber bush GB1 is formed with a hole or groove for holding one lamp cable LPC1 whereas the rubber bush GB2 is formed with a hole or groove for holding the fluorescent tube LP and the two lamp cables LPC1 and LPC2.

<<Accommodations of Fluorescent Tube LP, Lamp Cables LPC and Rubber Bushes GB in Lower Casing MCA>>

FIG. 39(A) is a top plan view showing the state in which the back light BL (including the fluorescent tube LP, the lamp cables LPC, the rubber bushes GB and the light guide plate GLB) in the lower casing MCA; FIG. 39(B) is a section taken along line B—B of FIG. 39(A); and FIG. 39(C) is a section taken along line C—C of FIG. 39(A).

In FIG. 37 showing the inner side (or upper side) of the lower casing MCA; letters MB designate a holding portion of the light guide plate GLB; letters ML designate an accommodation portion of the fluorescent tube LP; letters MG designate an accommodation portion of the rubber bushes GB; letters MC1 designate an accommodation portion of the lamp cable LPC1; and letters MC2 designate an accommodation portion of the lamp cable LPC2.

The back light BL is accommodated, as shown in FIGS. 39(A) to 39(C), in the lower casing MCA or the back light accommodating casing. Specifically, the rubber bushes GB1 and GB2 holding the fluorescent tube LP and the lamp cables LPC are fitted in the accommodation portion MG, which is formed to snugly fit the rubber bushes GB1 and GB2, as shown in FIG. 37, and the fluorescent tube LP is accommodated out of contact with the lower casing MCA in the accommodation portion ML. The line cables LPC1 and LPC2 are accommodated in the accommodation portions MC1 and MC2 which are composed of the grooves formed in the lower casing MCA substantially accurately along the shapes of the line cables LPC1 and LPC2. The line cables LPC1 and LPC2, as near the leading end to be connected with the inverter IV, i.e., at and downstream of the rubber bush GB2, turn generally at a right angle from the longer axis direction of the circuit substrate PCB2 (as shown in FIGS. 1 and 39) and are accommodated in the space between the mounting hole MB3 (of FIG. 37) and the circuit substrate PCB2. The leading end portions of the lamp cables LPC1 and LPC2 are connected with the inverter IV, which is accommodated in the inverter accommodating portion MI formed sideways of the circuit substrate PCB2, as shown in FIG. 39(A). Thus, in case the module MDL is assembled in an appliance such as a personal computer, the fluorescent tube LP, the lamp cables LPC, the rubber bushes GB and the inverter IV of the back light BL can be accommodated and packaged in compact such that neither the line cables LPC extend along the outer side of the module nor the inverter IV bulges out of the module MDL. As a result, the module MDL can be small-sized and light-weighted to reduce the production cost.

Incidentally, one fluorescent tube LP is arranged in the present embodiment, but two ore more can be arranged and at the shorter side of the light guide plate GLB.

<<Accommodation of Light Guide Plate GLB in Lower Casing MCA>>

FIG. 41 is a section of an essential portion of the lower casing MCA, the light guide plate GLB, the fluorescent tube LP, the lamp cables LPC and so on.

The light guide plate of the prior art has many useless regions for the holding purposes in the module and is far larger than the size of the effective light emitting portion. As shown in FIG. 39(A), on the contrary, the light guide plate GLB of the present embodiment has a square (or rectangular) shape so that its entire size can be made as similar to that of the light emitting portion as possible. The light guide plate GLB -has as its three sides snugly held on the inner wall of its accommodating portion of the lower casing MCA and its remaining one side held by the two small projections (or pawls) PJ, which are integrally formed with the lower casing MCA, in the vicinity of the rubber bushes GB on the inner (or upper) face of the lower casing MCA between the light guide plate GLB and the fluorescent tube LP. Those projections PJ prevent the light guide plate GLB from moving toward the fluorescent tube LP and from impinging to break the fluorescent tube LP. Incidentally, the lamp reflecting sheet LS has a rectangular shape, before applied, but has its longer end portion bonded, after applied, to the lower end face of the reflective sheet RS to over the fluorescent tube LP throughout the whole length and its other longer end portion placed on and held by the upper end portion of the prism sheet PRS. The lamp reflecting sheet LS is formed to have a U-shaped section and such a length that it is arranged in the projections PJ. These projections PJ are made as small as possible so that they may not reduce the utilizing efficiency of the light.

Thus, the light guide plate GLB is made as small as the effective light emitting portion so that the electronic parts can be packaged in the space which has been occupied by the light guide plate of the prior art. At the same time, the light guide plate GLB is held by the projections PJ which are made integral with the lower casing MCA so that the it can be held in a small space. As a result, the module MDL can be small-sized and light-weighted to reduce the production cost. In other words, the light emitting efficiency of the light guide plate GLB can be improved while realizing the size reduction of the module MDL.

Incidentally, the projections PJ need not always be made integral with the lower casing MCA, but projections made of separate members of a metal may be attached to the lower casing MCA.

<<Diffusive Sheet SPS>>

The diffusive sheet SPS is placed on the light guide plate GLB to diffuse the light emitted from the upper face of the light guide plate GLB thereby to irradiate the liquid crystal display panel PNL uniformly with the light.

<<Prism Sheet>>

The prism sheet PRS is placed on the diffusive sheet SPS and has a lower smooth face and an upper prism face. This prism face is formed of a plurality of grooves which have V-shaped sections arrayed straight in parallel with each other. The prism sheet PRS is enabled to improve the brightness of the back light BL by collecting the light, which is diffused over a wide angular range from the diffusive sheet SPS, in a direction normal to the prism sheet PRS. As a result, the back light BL can be made to consume a low power so that the module MDL can be small-sized and light-weighted to reduce the production cost.

<<Reflective Sheet RFS>>

The reflective sheet RFS is arranged below the light guide plate GLB to reflect the light emitted from the lower face of the light guide plate GLB toward the liquid crystal display panel PNL.

<<Holding Structure of Light Guide Plate GLB and Liquid Crystal Display Panel PNL>>

FIG. 42 is a section of an essential portion of the module MDL and shows a structure for holding the light guide plate GLB and the liquid crystal display panel PNL.

As shown in FIG. 42, the prism sheet PRS and the diffusive sheet SPS are made larger than the light guide plate GLB and their end portions protruded (or overhung) from the end portion of the light guide plate GLB onto the side wall of the lower casing MCA. On the overhung portions of the prism sheet PRS and the diffusive sheet SPS and the side wall of the lower casing MCA, there are arranged the rubber cushion GC and the shade spacer ILS which is made of rubber, to push and hold the upper transparent glass substrate SUB2 of the liquid crystal display panel PNL (as will be described in <<Holding Structure of Liquid Crystal Display Panel PNL>> and with reference to FIG. 44). As a result, both of the prism sheet PRS and the diffusive sheet SPS or only the diffusive sheet SPS steals into the gap between light guide plate GLB and the lower casing MCA so that the light guide plate GLB is prevented from chattering and is firmly held in the module MDL. According to the structure shown in FIG. 42, the pressures of the rubber cushions GC and the shade spacer ILS are applied through the prism sheet PRS and the diffusive sheet SPS to the lower casing MCA so that the liquid crystal display panel PNL is reliably held in the module MDL to improve the holding forces of the light guide plate GLB, the liquid crystal display panel PNL and so on thereby to improve the reliability of the product.

Here, both the prism sheet PRS and the diffusive sheet SPS are overhung from the light guide plate GLB, but one of them may be overhung. Here, moreover, the overhang is made over the whole periphery on four sides of the light guide plate GLB, but an effect can be achieved even the overhand is at one to three sides.

<<Holding Structure of Liquid Crystal Display Panel PNL>>

FIG. 45 is a section of an essential portion and shows a holding structure of the liquid crystal display panel PNL in the liquid crystal display module MDL of the prior art. FIG. 44 is a section of an essential portion and shows a holding structure of the liquid crystal display panel PNL in the liquid crystal display module MDL of one embodiment of the present invention.

In the liquid crystal display module MDL of the prior art, as shown in FIG. 45, both the two transparent glass substrates constructing the liquid crystal display panel PNL are held through the rubber cushions GC so as to fix the liquid crystal display panel PNL in the module MDL. Specifically, as has been described in detail in <<Shield Casing SHD>>, the shield casing SHD is pushed into the device by making use of the elasticity of the rubber cushions GC so that the shield casing SHD and the lower casing MCA are fixed by the individual fixing members (that is, the fixing hooks HK are fixed by the fixing projections HP whereas the fixing pawls NL are folded inward and inserted into the fitting recesses NR). As a result, a the two transparent glass substrates are forcibly pushed in the prior art through the rubber cushions GC so that the liquid crystal between the two transparent glass substrates of the liquid crystal display panel PNL has its gap locally changed to cause a display unevenness. As a result, the liquid crystal display panel PNL cannot be so strongly pushed as to fail to retain a sufficient mechanical strength. According to the present invention, on the contrary, the two transparent glass substrates constructing the liquid crystal display panel PNL are given different sizes, that is, one transparent glass substrate is protruded from the other transparent glass substrate as to the side (as located at the side of the interface circuit substrate PCB3) having no terminal arranged, and the single glass plate portion is disposed all over the three sides of the liquid crystal display panel PNL so that only one transparent glass substrate is held through the rubber cushions GC placed on said single glass plate portion. As a result, the gap between the two transparent glass substrates is not changed to cause no display unevenness even if they are strongly pushed. As a result, the pushing force of the liquid crystal display panel PNL can be increased to improve the mechanical strength and the reliability. Moreover, the upper face of the single glass plate portion of the liquid crystal display panel PNL and the lower (or inner) face of the metallic shield casing SHD has a double sided adhesive tape BAT sandwiched inbetween so that they are fixed. Incidentally, FIG. 44 is a view schematically showing the holding structure of the liquid crystal display panel PNL. As a mater of fact, the light guide plate of GLB is interposed between the rubber cushion GC and the lower casing MCA.

Incidentally, in the embodiment shown in FIG. 44, the structure is not limited to that in which the prism sheet PRS is overhung, as described above, so that the prism sheet PRS is not hung over the light guide plate GLB.

Although the present invention has been specifically described on the basis of its embodiments, it should not be limited thereto but can naturally be modified in various manners without departing from the gist thereof.

[Effects of the Invention]

As has been described hereinbefore, according to the liquid crystal display device of the present invention, the area of the frame portion around the display can be reduced by arraying the video signal line driving circuit substrate at only one of the sides of a display panel, so that the liquid crystal display device and the data processing device having the former assembled therein can be small-sized and light weighted. Moreover, the display unevenness can be prevented to improve the display quality, and the holding force of the liquid crystal panel in the device can be increased. As a result, the mechanical strength can be improved to improve the reliability. Thanks to the excellent using efficiency of the space for accommodating the fluorescent tube, still moreover, the liquid crystal display device can have its external size reduced so that it can be small-sized and light-weighted to reduce the production cost.

According to the present invention, on the other hand, the light guide plate and the liquid crystal display panel can be firmly held in the device without enlarging the external size to improve the mechanical strength. At the same time, the device can be small-sized and light-weighted to reduce the production cost. Since, moreover, the cables of the fluorescent tube of the back light can be accommodated without bulging out of the device, this device can be small-sized and light-weighted to reduce the production cost. Still moreover, it is possible to improve the holdability of the fluorescent tube. Furthermore, the light guide plate of the back light can be held in the small space so that the device can be small-sized and light-weighted to reduce the production cost. Furthermore, the bottom face of the mold casing has its central portion formed with a large opening so that it can be prevented from bulging out to reduce the size and weight of the liquid crystal display device. Furthermore, the cables and the inverter of the back light can be accommodated without bulging out of the device so that the liquid crystal display device can be small-sized and light-weighted to reduce the production cost.

According to the present invention, on the other hand, it is possible to provide a liquid crystal display device having such a circuit as can improve not only the heat liberation of the exothermic portions, the highly dense packageability of the circuit and the compactness and as can realize the multi-gradation, the single power source and the compact packaging. Moreover, the number of electronic parts can be reduced to reduce the cost for the material and the number of working steps. As a result, the production cost can be reduced to improve the reliability of the product.

According to the present invention, on the other hand, the plate extracting efficiency of the circuit substrate is enhanced to reduce the cost for the material of the circuit substrate thereby to reduce the production cost for the liquid crystal display device. Moreover, a plurality of circuit substrates can be electrically connected with a small space so that the liquid crystal display device can be small-sized and light-weighted to reduce the production cost and to take an advantage in the high performance of the device. Even in case, still moreover, the liquid crystal display device is formed at its intermediate portion with a mounting hole for mounting it in an appliance such as a personal computer, the drawn portion of the metallic casing to be formed with the mounting hole can be generally reduced to a quadrant shape. As a result, the liquid crystal display device can be small-sized and light-weighted to reduce the production cost.

According to the present invention, on the other hand, the pawls, as made integral with the side face of the metallic shield casing, are connected with the frame ground pads on the circuit substrate, as connected with the ground wiring lines. As a result, the harmful radiative electric waves can be suppressed, and the folding and soldering workability of the pawls can be improved to improve the connection reliability. Still moreover, the casing of the liquid crystal display device has its corner firmly held and fixed through the mounting holes by the screws or the like so that the mechanical strength is improved to improve the product reliability. Furthermore, a plurality of electronic parts for counter-measures of the EMI are arranged concentratedly on the circuit substrate so that the dead space can be reduced to package the electronic parts highly densely. As a result, the liquid crystal display device can be small-sized and light-weighted to reduce the production cost.

Claims

1. A liquid crystal display device comprising:

a liquid crystal display panel, including an upper shield casing accommodating at least one insulating substrate and having at least first and second sides, and a lower casing being connectable to the upper shield casing, the lower casing having at least first and second sides with one of the first side of the upper shield casing and the lower casing being provided with hooks and the other of the first side of the upper shield casing and the lower casing being provided with projections for receiving the hooks and enabling connection of the upper shield casing and the lower casing, and one of the second side of the upper shield casing and the lower casing having fixing pawls and the other of the second side of the upper shield casing and the lower casing having recesses for receiving the fixing pawls so as to enable connection of the upper shield casing and the lower casing.

2. A liquid crystal display device according to claim 1, wherein the upper shield casing accommodates first and second insulating substrates superposed at a predetermined gap such that faces thereof are respectively formed with electrodes and an orientation film and are opposed to each other, in which said two substrates are adhered to each other through a seal member applied in a frame shape on edge portions between said two substrates while sealing a liquid crystal in said seal member between said two substrates, and in which a plurality of scanning signal lines and video signal lines arrayed on a surface of said first insulating substrate have their individual terminals disposed outside of said seal member; and

wherein a video signal line driving circuit substrate is arranged on only one longer sides of said liquid crystal display panel and is connected with the terminals of said video signal lines.

3. A liquid crystal display device according to claim 2,

wherein no circuit substrate is arranged at the other side of said display panel which is arranged with said video signal line driving circuit substrate.

4. A liquid crystal display device according to claim 2,

a light guide plate arranged below said liquid crystal display panel,

a fluorescent tube arranged in the vicinity of at least one side face of said light guide plate,

and a plurality of tape carrier packages arranged on the outer peripheral portion of said liquid crystal display panel;

wherein said fluorescent tube is arranged below said plurality of tape carrier packages.

5. A liquid crystal display device according to claim 1, wherein at least one of the upper shield casing and the lower casing accommodate a backlight therein and disassembly of a connected upper shield casing and lower casing for repair of the backlight is enabled by removing a portion of the fixing pawls.

6. A liquid crystal display device according to claim 1, wherein the first and second sides are arranged on opposite sides of the upper shield casing and the lower casing.

7. A liquid crystal display device according to claim 1, wherein at least one circuit substrate is accommodated in at least one of the upper shield casing and the lower casing and no circuit substrate is arranged in the first side of the upper shield casing and the lower casing.

8. A liquid crystal display device comprising:

a first circuit substrate arranged outside of a first side of a liquid crystal display panel for driving signal lines,

a second circuit substrate arranged outside of a second side adjacent to and perpendicular to said first side and having a connector for connection with the outside,

a first casing having a first mounting hole in the vicinity of its corner for accommodating said liquid crystal display panel and said first and second circuit substrates,

a back light disposed with respect to said liquid crystal display panel,

and a second casing having a second mounting hole aligned with said first mounting hole for accommodating said back light;

wherein said first casing and said second casing are united together, said second circuit substrate is equipped with an electronic part disposed at its end portion most remote from said first circuit substrate, said connector of said second circuit substrate is arranged adjacent to said electronic part and extends in a direction substantially parallel to said second side;

a plurality of circuit substrates divided and arranged at the two, three or four sides of an outer peripheral portions of said liquid crystal display panel,

and a casing for accommodating said liquid crystal display panel and said circuit substrates together and formed with mounting holes,

wherein at least one of said mounting holes is arranged at a distance from a corner of said casing, and in that said circuit substrate having a generally rectangular shape with corners are divided into a plurality of sheets and are electrically connected in a vicinity of said corners by joiners.

9. A liquid crystal display device according to claim 8,

wherein said mounting holes are positioned at intermediate portions spaced at a predetermined distance from the corners of said casing and in a drawn portion which is made integral with a metal plate forming said casing and which forms a parallel plane at a different level as that of said metal plate,

said drawn portion is given generally a quadrant shape,

said quadrant shape is formed with a notch in its radial portion between said drawn portion and said metal plate adjacent to said drawn portion.

10. A liquid crystal display device according to claim 8,

wherein said circuit substrates are electrically connected with each other through at least two joiners which are superposed at two or more stages in a thickness direction of said display device.

11. A liquid crystal display device comprising:

a first circuit substrate arranged outside of a first side of a liquid crystal display panel for driving signal lines,

a second circuit substrate arranged outside of a second side adjacent to and perpendicular to said first side and having a connector for connection with the outside, and a signal source integrated circuit,

a first casing having a first mounting hole in a vicinity of a corner for accommodating said liquid crystal display panel and said first and second circuit substrates,

and a second casing having a second mounting hole aligned with said first mounting hole for uniting said first casing;

wherein said connector disposed between said first circuit substrate and said signal source integrated circuit, said connector of said second circuit substrate is arranged adjacent to said signal source integrated circuit and extends in a direction substantially parallel to said second side.

12. A liquid crystal display device comprising:

a liquid crystal display panel having longer sides and shorter sides;

a video signal line driving circuit substrate connected to only one of said longer sides of said liquid crystal display panel;

a light guide plate arranged below said liquid crystal display panel;

a fluorescent tube arranged on at least one side face of said light guide plate;

a shield casing for accommodating the circumferential portion of said liquid crystal display panel;

a mold casing monolithically molded for accommodating said light guide plate and said fluorescent tube;

two cables having respective one ends thereof connected with two ends of said fluorescent tube;

first and second retaining members for retaining the two ends of said fluorescent tube, respectively; and

first, second and third grooves integral with said mold casing;

wherein said first and second grooves respectively accommodate said first and second retaining members so that said first and second retaining members are snugly fitted therein;

at least one of said two cables is accommodated in said third groove which is integral with a side wall of said mold casing;

said shield casing and said mold casing being coupled together; and

said third groove and said fluorescent tube being arranged to extend along one of said longer sides of said liquid crystal display panel.

13. A liquid crystal display device according to claim 12, wherein said third groove of said mold casing extends in a direction of extension of said fluorescent tube.

14. A liquid crystal display device according to claim 12, wherein said third groove of said mold casing is proximate to said fluorescent tube.

15. A liquid crystal display device comprising:

a liquid crystal display panel;

a light guide plate disposed below the liquid crystal display panel;

a fluorescent tube arranged on one side face of the light guide plate;

a lamp reflector reflecting light of the fluorescent tube to the light guide plate;

a first lamp cable connected to the fluorescent tube, and a second lamp cable connected to the fluorescent tube, the second lamp cable having a length which is shorter than a length of the first lamp cable; and

a mold case accommodating the light guide plate, the fluorescent tube, the lamp reflector, and the first lamp cable;

wherein one end of the fluorescent tube is inserted in a hole of a first rubber bush, and a part of the one end of the fluorescent tube is connected to the first lamp cable in the hole of the first rubber bush;

wherein an other end of the fluorescent tube is inserted in a hole of a second rubber bush, and a part at the other end of the fluorescent tube is connected to the second lamp cable in the hole of the second rubber bush; and

wherein the first lamp cable is inserted and held in the second rubber bush.

16. A liquid crystal display device according to claim 15, wherein the first lamp cable and the second lamp cable are extracted in a same direction from the second rubber bush.

17. A liquid crystal display device according to claim 15, wherein the first lamp cable is inserted in a groove formed in the second rubber bush.

18. A liquid crystal display device according to claim 16, wherein the first lamp cable is inserted in a groove formed in the second rubber bush.