Information transmission system using light as communication medium, information transmission method, image pickup device, and computer programmed product

Abstract

A CPU 36 of a light emitting unit 30 fetches ith bit of transmission information TX stored in a transmission data memory 33 in synchronization with a clock signal CK from a timing generator 35. The CUP 36 determines the bit value and fetches a first pattern sequence SA from a pattern data memory 44 when the bit is logic signal 1, and fetches a second pattern sequence SB from a pattern data memory 34 when the bit is logic signal 0, and outputs the first pattern sequence SA and second pattern sequence SB to a light emitting section 37. While, a CPU 39 of a light receiving unit 40 extracts a pixel area with a time sequence luminance variation pattern from a frame image captured into a capture image buffer 46, and binarizes the luminance variation pattern, and performs logic determination. A liquid crystal display 44 displays information of a light emitting area to be overlapped with a subject image.

Description

Data of the reading area range is fetched based on the threshold level thus determined. The fetched data is compared with the previous data to perform motion correction processing, so that sample dot coordinates to be detected are determined (step S81). Then, the resultant data is subjected to logic determination at the threshold level determined in step S80 to fetch the source data bit sequence one bit by one and to perform decoding processing (step S82)

FIG. 35 is a conceptual view of a logical determination. This shows a case in which the value of less than the threshold level is set to logic signal 0 and the value of equal to or more than the threshold level is set to logic signal 1 to determine a transmission data level based on the determination of threshold level of FIG. 34.

Finally, it is determined whether or not the mode is shifted to a signal detection and acquisition mode after escaping a decoded data display mode in response to the user's operations (specific key operation, etc.) (step S84), and a series of processing is ended.

In this way, according to the fourth embodiment, modulation for detection and modulation for information transmission (baseband modulation) are superimposed on each other and the luminance variations are set to “OFF”, “ON (L)”, “ON(H)”. For this reason, this is a simple and high-rate signal detection method that is strong against disturbance, and this makes it possible to transmit and reproduce a satisfactory image character sequence even if the luminance variation is detected in a small area.

Further, in the detection and acquisition mode, area image data is obtained in advance, and motion correction is performed with correlation between the frames to make it possible to ensure a satisfactory detection performance even if variations such as hand movements occur.

Further, in the detection and acquisition mode, in connection with each area where the user designates the detection area, the operation enters the decoding mode. However, such a configuration that is capable of designating a plurality of areas to be read is provided, making it possible to transfer data to the plurality of areas within time of one frame rate period.

Accordingly, data reading of each area at a given frame rate is performed on a plurality of portions, thereafter entering the decode mode. This makes it possible to configure the apparatus that performs decoding processing on the plurality of areas concurrently.

Moreover, in the fourth embodiment, the baseband modulation is used in the decoding mode. However, a code spread modulation can be used. In this case, it is possible to extremely increase the robustness against variations in detection noise of sensor and image pickup conditions.

Various embodiments and changes may be made there-unto without departing from the broad spirit and scope of the invention. The above-described embodiments are intended to illustrate the present invention, not to limit the scope of the present invention. The scope of the present invention is shown by the attached claims rather than the embodiments. Various modifications made within the meaning of an equivalent of the claims of the invention and within the claims are to be regarded to be in the scope of the present invention.

This application is based on Japanese Patent Application No. 2001-288428 filed on Sep. 21, 2001 and including specification, claims, drawings and summary. The disclosure of the above Japanese Patent Application is incorporated herein by reference in its entirety.

Claims

1. An information transmission system comprising a light emitting unit that converts arbitrary information into an optical signal to output and a light receiving unit that receives said optical signal to reproduce said information,

said light emitting unit including:

determining means for logically determining a bit sequence that structures said arbitrary information;

selecting means for selecting a specific bit pattern sequence from two bit pattern sequences having a low correlation with each other, pre-prepared based on the determination result by said determining means;

modulating means for modulating said arbitrary information to light intensity according to the selection result by said selecting means; and

output controlling means for performing control to output the optical signal with intensity modulated by said modulating means;

said light receiving unit including:

binarizing means for receiving the optical signal output from said light emitting unit to binarize according to the light intensity;

bit pattern determining means for determining whether or not the bit pattern sequence included in the signal binarized by said binarizing means corresponds to any one of said pre-prepared two bit pattern sequences having a low correlation with each other;

signal outputting means for outputting a logic signal corresponding to the bit pattern sequence determined by said bit pattern determining means; and

reproducing means for reproducing said arbitrary information based on the output result from said signal outputting means.

2. The information transmission system according to claim 1, wherein said modulating means modulates said arbitrary information to light intensity including an OFF state corresponding to non-lighting state, an ON(L) state corresponding to a low luminance lighting state and an ON(H) corresponding to a high luminance lighting state.

3. The information transmission system according to claim 1, wherein said modulating means adds a bit signal such that frequencies of appearance of logic signals different from each other on said light receiving unit side are balanced so as to modulate light intensity in connection with the specific bit sequence selected by said selecting means.

4. The information transmission system according to claim 1, wherein said light receiving unit further includes image pickup means, and output light from said light emitting unit is received by performing image pickup by said image pickup means.

5. The information transmission system according to claim 4, wherein said light receiving unit further includes scanning means for scanning an area subjected to image pickup by said image pickup means, and means for specifying the area of said output light based on the scanning result by said scanning means, said binarizing means binarizes said specified area, and said bit pattern determining means determines whether or not the bit pattern sequence included in the binarized signal corresponds to any one of said pre-prepared two bit pattern sequences having a low correlation with each other.

6. The information transmission system according to claim 5, wherein said light receiving unit further includes dividing means for dividing the area subjected to image pickup by said image pickup means into a plurality of areas, and said scanning means for scanning the respective areas divided by said dividing means, sequentially.

7. The information transmission system according to claim 6, wherein said light receiving unit further includes changing means for changing the size of area to be divided by said dividing means with arbitrary timing.

8. The information transmission system according to claim 6, wherein said light receiving unit further includes sub-sampling means, and area changing means for changing the size of area to be divided by said dividing means by said sub-sampling means.

9. The information transmission system according to claim 5, wherein said light receiving unit further includes means for determining a threshold level of an area scanned by said scanning means, and said binarizing means binarizes the area based on the threshold level determined said means.

10. The information transmission system according to claim 4, wherein said light receiving unit further includes display means for displaying the areas subjected to image pickup by said image pickup means, area selecting means for selecting an area of said output light from among the areas displayed on said display means, and designating means for designating said reproducing means to perform information reproduction on the area of output light selected by said area selecting means.

11. The information transmission system according to claim 10, wherein said light receiving unit further includes display controlling means for causing said display means to display information reproduced by said reproducing means in response to designation from said designating means.

12. An information transmission method that converts information to be transmitted into an optical signal to output by a light emitting unit and that receives said optical signal by a light receiving unit to reproduce said information, said method comprising the steps of:

logically determining a bit sequence that structures information to be transmitted;

selecting a bit pattern sequence alternatively from two bit pattern sequences having a low correlation with each other, pre-prepared according to the result determined in said logic determining step;

outputting the optical signal with intensity modulated according to the result selected in said selecting step;

binarizing the optical signal received according to intensity;

determining whether or not the bit pattern sequence included in the result binarized in said binarizing step corresponds to any one of said pre-prepared two bit pattern sequences having a low correlation with each other;

generating a corresponding logic signal when the bit pattern sequence corresponds to any one of said two bit pattern sequences is determined in said determining step; and

reproducing said information based on the logic signal generated in said generating step.

13. The information transmission method according to claim 12, further comprising the steps of:

capturing an output light from said light emitting unit as an image of an area including said output light; and

displaying the image captured in said capturing step and reproduced information.

14. An image pickup device comprising:

image pickup means;

storage means for storing two bit pattern sequences having a low correlation with each other;

scanning means for scanning an area subjected to image pickup by said image pickup means;

means for specifying an output light area subjected to intensity modulation based on the result scanned by said scanning means;

binarizing means for binarizing the output light area specified by said means according to light intensity;

bit pattern determining means for determining whether or not the bit pattern sequence included in the signal binarized by said binarizing means corresponds to any one of said two bit pattern sequences having a low correlation with each other, stored in said storage means;

signal outputting means for outputting a logic signal corresponding to the bit pattern sequence determined by said bit pattern determining means; and

reproducing means for reproducing information based on the output result from said signal outputting means.

15. The image pickup device according to claim 14, further comprising:

dividing means for dividing the area subjected to image pickup by said image pickup means into a plurality of areas, and said scanning means scanning the respective areas divided by said dividing means, sequentially.

16. The image pickup device according to claim 15, further comprising:

changing means for changing the size of area to be divided by said dividing means with arbitrary timing.

17. The image pickup device according to claim 15, further comprising:

sub-sampling means; and

area changing means for changing the size of area to be divided by said dividing means by said sub-sampling means.

18. The image pickup device according to claim 14, further comprising:

display means for displaying the areas subjected to image pickup by said image pickup means;

area selecting means for selecting said output light area from among the areas displayed on said display means; and

designating means for designating said information output means to perform information output on the output light area selected by said area selecting means.

19. The image pickup device according to claim 18, further comprising:

display controlling means for causing said display means to display information output by said information output means in response to designation from said designating means.

20. A computer programmed product having a computer-program recorded on storage computer-readable storage medium, said computer-program causing non-transitory computer readable storage medium having a computer program stored thereon that is executable by a computer, being connected to an image pickup device, to execute steps of including:

scanning an area subjected to image pickup by said image pickup device;

specifying an output light area subjected to intensity modulation based on said scanned result;

binarizing said specified output light area according to light intensity;

determining whether or not a bit pattern sequence included in the signal binarized by said binarizing means corresponds to any one of pre-prepared two bit pattern sequences having a low correlation with each other;

outputting a logic signal corresponding to said determined bit pattern sequence; and

outputting information based on said output result in said signal outputting step.