Method for forming partitions of plasma display panel by using sandblasting process

Abstract

A partition is formed by the process including a step for providing a sheet-like partition material that covers a display area and outside thereof on the surface of the substrate, a step for providing a mask for patterning that covers the display area and the outside thereof, so that a pattern of the portion arranged outside of the display area of the mask is a grid-like pattern, a step for patterning the partition material covered partially with the mask by a sandblasting process, and a step for baking the partition material after the patterning.

Description

Here, L1 represents the width of bands except for both ends of the arrangement in the display area 10, L2 represents the width of the most outside band, and L3 represents the width of bands except for the most outside band in the non-display area 11. In this way, a patterning error of vanishing the most outside portion of the partition pattern can be prevented by setting the band width of the most outside portion to the largest value.

As explained above, the nozzle is moved in the vertical direction in FIG. 4 in the cutting process. Along with the movement of the nozzle, the cutting material is first ejected toward the auxiliary mask 5 located at the upper or the lower non-display area 11, then the cutting material is ejected toward the sub mask 4b, and further the cutting material is ejected toward the main mask 3b. Since the cutting process can be performed faster as the pattern gap of the mask is larger, the cutting action is the largest for the auxiliary mask 5. The auxiliary mask 5 has also a function for preventing excessive cutting of the sub mask 4b. If the auxiliary mask 5 is exfoliated and blown off, the sub mask 4b prevents excessive cutting for the main mask 3b.

Making the corner portion of the sub mask 4b in an arcuate shape is effective for reducing the projection. It is considered to be important for the reason to distribute a stress due to contraction in the baking process so that the locally generated projections can be distributed and averaged. Concerning the pattern of the corner portion, there is a variation as shown in FIG. 6. The corner portion of a sub mask 4c as shown in FIG. 6(A) has a shape of a right-angled rim in which one of squares is filled. The corner portion of a sub mask 4d as shown in FIG. 6(B) has an arcuate shape having a radius twice the grid interval. The corner portion of a sub mask 4e as shown in FIG. 6(C) has a shape of laterally oblong arc. As shown in FIG. 7, the quantity of a projection depends on a shape of the corner portion. The quantity of a projection is less in the arcuate corner portion than in the angled corner portion. Also, the quantity of a projection is less in a large radius than in a small radius of the arc. Even the arc of small radius can realize the quantity of a projection of 16 μm or less that is effective for reducing operational sound. However, considering variation in a manufacturing process, it is desirable to set the quantity of a projection to 12 μm or less.

FIG. 8 is a plan view showing a first variation of an auxiliary mask pattern. The pattern of an auxiliary mask 5b is a pattern having three coaxial rings elongated in the lateral direction and consisting of half circles and lines. However, a slit 51a is formed in each half circle at each end of each ring, so the pattern of the auxiliary mask 5b is a discontinuous ring pattern in the strict sense. Since the slit 51a divides the ring, only a part of a ring is blown off if partial mask exfoliation occurs in the cutting process of the entire of one ring, and it is hard to occur that the entire of one ring is blown off.

The ring pattern is made by connecting both ends of a band with each other in the stripe pattern, and the exfoliation hardly occurs in it compared with the stripe pattern. Since ends of all rings including the most inside ring protrude from the mask 30b, the effect of protecting the mask 30b is enhanced.

FIG. 9 is a plan view showing a second variation of an auxiliary mask pattern. In this example, the pattern of the partition mask 3b located at the display area 10 is a mesh pattern. An auxiliary mask 5c is positioned at the vicinity of a mask 30c that includes the main mask 3b and the sub mask 4b. The pattern of the auxiliary mask 5c is a stripe pattern in which a plurality of bands shorter than the entire length in the lateral direction of the display area 10 is arranged in the moving direction as a plurality of discontinuous lines that are parallel to each other. In this pattern, the jet can be controlled by setting the width of the slit 55 that divides the band of the stripe. There is also an effect that a portion that will be blown off is small when mask exfoliation occurs. The slits 55 are arranged so that the discontinuous points of plural discontinuous lines are shifted from each other, and thereby the jet is prevented from being enhanced locally in the sub mask 4b.

The both ends of the auxiliary mask 5c protrude from the mask 30b by the length L11. However, the band closest to the mask 30b among bands constituting the stripe pattern is not protruded from the mask 30b. The reason thereof is to make the exfoliation of a band that will contribute to the protection of the mask 30b most hard to happen. If this band is exfoliated at early stage, quantity of side cut of the sub partition increases compared with the case where other bands are exfoliated. Since the ends of the band are not protruded from the mask 30b, jet pressure will be weaken at the end of the band. Furthermore, the shape of the band that is closed to the mask 30b can be adopted also for the auxiliary mask of the embodiment as shown in FIG. 5.

FIG. 10 is a plan view showing a third variation of an auxiliary mask pattern. Also in this example, the partition pattern is a mesh pattern. The pattern of an auxiliary mask 5d is a stripe pattern in which a plurality of bands sufficiently shorter than the entire length in the moving direction of the display area 10 is arranged in the moving direction as a plurality of discontinuous lines that are parallel to each other. In this pattern, it is important to set the length of the band of the stripe to a value within the range of 0.05-200 mm. The longer the band is, the easier the band can be entangled with a movable mechanism of a conveyor 91 (see FIG. 1) when it is blown off. The entanglement of a mask flake is not desirable for stability of the movement and for cleaning the conveyor 91. The above-mentioned range is a condition for easy collection by the filter 97 without any entanglement. The distance between the short bands arranged linearly is preferably about a fifth of the length of the band. In addition, a preferred condition considering reduction of the projection is that the width and the length of the band is less than 240 μm (=0.24 mm). It is confirmed by the experiment that when the condition is satisfied, the quantity of a projection becomes less than a few μm even if a side cut having the depth of 50 μm is generated either in the width direction or in the length direction. This can be explained that if the band is longer than 240 μm, the edge portion is pulled by shrink of the long portion so as to generate the projection while the projection is hardly generated if it is shorter than 240 μm since there is no pulling portion.

(Third Embodiment)

FIG. 11 is a plan view showing a mask pattern of a third embodiment. The third embodiment is applied to a multiple making process in which partitions for a plurality of PDPs are formed on one substrate simultaneously, and then the substrate is divided. The example shown in FIG. 11 shows an example in which partitions for three PDPs are formed simultaneously, and each of the three display areas 10a, 10b and 10c in FIG. 11 corresponds to a partition portion of one PDP. The partition pattern of the PDP of the third embodiment is also a stripe pattern. The partition is formed by the process in the same way as the first embodiment, which includes patterning a sheet-like partition material 2c that covers the entire surface of a glass substrate 1c by using a sandblasting process and a mask 30b that is a unit of a main mask and a sub mask, and then baking the partition material 2c. The glass substrate 1c has a size of 1460 mm×1050 mm for manufacturing a 32-inch PDP.

The display areas 10a, 10b and 10c are arranged with a space along the vertical direction in FIG. 11, and one mask 30b is arranged for each of them. In addition, auxiliary masks 6a, 7a, 6b and 7b are formed in the non-display areas 11a and 11b between the neighboring display areas at the same time as formation of the mask 30b. The auxiliary masks 6a, 7a, 6b and 7b-reduce the jet pressure toward the sub partition that is formed by the mask 30b. When the nozzle is moved in the arrangement direction of the display area, the middle portion in the moving direction of the glass substrate 1c receives larger jet pressure than the end portions do. It is because that approximately a half of the jet deviates to the outside the glass substrate 1c at the end portions. The arrangement of the auxiliary masks 6a, 7a, 6b and 7b at portions that receive large jet pressure can prevent the mask 30b from being exfoliated, so that exact partitions as designed can be formed in the display areas 10a, 10b and 10c. In the photolithography process for forming the three masks 30b and the auxiliary masks 6a, 7a, 6b and 7b, a stepper type pattern exposure is performed in which one photo mask having a size corresponding to one PDP is used three times. For this reason, auxiliary masks are formed actually also for each of the display areas 10a, 10b and 10c similarly, as shown in FIG. 11.

As explained above, according to the present invention, concerning a projection based on the display portion, over the entire area of the partition forming portion including the sub partition portion and its corner portion and auxiliary partition portion, the quantity of a projection can be suppressed to 12 μm or less. Even if variation among manufactured panels is taken into account, it can be suppressed to 16 μm or less. Thus, operation sound (buzz sound) due to vibration during operation of the panel can be suppressed.

Though the present invention has been explained using various embodiments and variations, the present invention is not limited to these embodiments but can be realized in other embodiments.

INDUSTRIAL APPLICABILITY

The method for forming partitions according to the present invention enables formation of partitions having exact pattern and height as designed in a display area without generating projections that may disturb the contact between substrates. Therefore, it is useful for improving yields in manufacturing the plasma display panel that can be lowered due to patterning errors and for providing a plasma display panel that does not generate vibration sound due to insufficient contact between substrates.

Claims

1. A method for forming partitions of a plasma display panel, the partitions dividing a discharge space of a plasma display panel, the method comprising the steps of:

providing a sheet-like partition material on a substrate that is a panel material, the partition material covering a display area and a non-display area outside thereof of the display area on a surface of the substrate;

providing a mask for patterning on the partition material, the mask covering the display area and the outside thereof non-display area so that a pattern of the portion arranged in the display area of the mask corresponds to the partitions, and a pattern of the portion arranged in the non-display area outside of the display area of the mask is a pattern for dividing a band-like portion along a rim of the display area as a grid into a plurality of cells arranged in a plurality of rows and a plurality of columns;

patterning the partition material covered partially with the mask by a sandblasting process; and

baking the partition material after the patterning;

wherein a corner portion of the mask is arcuate.

2. The method for forming partitions of a plasma display panel according to claim 1, further comprising the steps of:

providing the mask so as to cover the display area and both sides thereof in a first direction; and

moving a nozzle for ejecting a cutting material relatively to the partition material in the first direction in a reciprocating manner while patterning the partition material by the sandblasting process.

3. The method for forming partitions of a plasma display panel according to claim 2, further comprising the step of forming an auxiliary mask outside the mask in the first direction with a distance from the mask at the same time when forming the mask.

4. The method for forming partitions of a plasma display panel according to claim 3, wherein both ends of the auxiliary mask in a second direction that is perpendicular to the first direction protrudes from the mask.

5. The method for forming partitions of a plasma display panel according to claim 4, wherein the pattern of the auxiliary mask is a stripe pattern in which a plurality of long bands is arranged in parallel in the second direction.

6. The method for forming partitions of a plasma display panel according to claim 4, wherein the pattern of the auxiliary mask is a stripe pattern in which a plurality of long thin bands is arranged in parallel in the second direction and at least both ends of the band that is closest to the mask are not protruded from the mask.

7. The method for forming partitions of a plasma display panel according to claim 4, wherein the pattern of the auxiliary mask is a ring pattern that is oblong in the second direction.

8. The method for forming partitions of a plasma display panel according to claim 1, wherein a corner portion of the mask has an arcuate shape.

9. The method for forming partitions of a plasma display panel according to claim 4, wherein the pattern of the auxiliary mask is a pattern in which a plurality of bands that is shorter than the entire length of the display area in the second direction is arranged in parallel to each other as a plurality of discontinuous lines along the second direction.

10. The method for forming partitions of a plasma display panel according to claim 9, wherein discontinuous points are shifted from each other among the plural discontinuous lines in the pattern of the auxiliary mask.

11. The method for forming partitions of a plasma display panel according to claim 9, wherein the length of the band in the pattern of the auxiliary mask has a value within the range of 0.05-200 mm.

12. The method for forming partitions of a plasma display panel according to claim 9, wherein both the width and the length of the band in the pattern of the auxiliary mask have a value less than 240 μm.

13. The A method for forming partitions of a plasma display panel according to claim 1 , the partitions dividing a discharge space of a plasma display panel, the method comprising the steps of:

providing a sheet-like partition material on a substrate that is a panel material, the partition material covering a display area and a non-display area outside of the display area on a surface of the substrate;

providing a mask for patterning on the partition material, the mask covering the display area and the non-display area so that a pattern of the portion arranged in the display area of the mask corresponds to the partitions, and a pattern of the portion arranged in the non-display area outside of the display area of the mask is a pattern for dividing a band-like portion along a rim of the display area as a grid;

patterning the partition material covered partially with the mask by a sandblasting process; and

baking the partition material after the patterning;

wherein at least the width of the band located at the most outside portion among the bands constituting a grid-like pattern of the portion arranged outside of the display area of the mask has a value within the range of 160-320 μm.

14. A method for forming partitions that divide a discharge space in each of plural plasma display panels simultaneously, the method comprising the steps of:

providing a sheet-like partition material on a substrate that is a panel material on which display areas corresponding to the plural plasma display panels respectively are arranged linearly, the partition material covering the plural display areas and non-display areas outside thereof of the display areas on a surface of the substrate;

providing a mask for patterning on the partition material, the mask covering the inside and the outside of the display area for each display area, so that a pattern of the portion arranged in the display area of the mask corresponds to the partitions, and a pattern of the portion arranged in the non-display area outside of the display area of the mask is a pattern for dividing a band-like portion along a rim of the display area as a grid;

forming an auxiliary mask at least between neighboring masks with a distance from the mask at the same time when forming the mask;

patterning the partition material covered partially with the mask and the auxiliary mask by a sandblasting process; and

baking the partition material after the patterning.

15. The method for forming partitions of a plasma display panel according to claim 1, wherein the arcuate corner portion of the mask is continuously curved.

16. The method for forming partitions of a plasma display panel according to claim 1, wherein an inside of a part of one of the cells in the corner portion of the mask has a continuously curved shape.