Coordinate position inputting/detecting device, a method for inputting/detecting the coordinate position, and a display board system

• US 6,421,042 B1
• Filed: 06/09/1999
• Issued: 07/16/2002
• Est. Priority Date: 06/09/1998
• Status: Expired due to Term

• Current Assignee: Smart Technologies ULC (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Ricoh Company Limited
• Inventors: Inoue, Takao, Omura, Katsuyuki
• Primary Examiner(s): Zimmerman, Mark
• Assistant Examiner(s): Monestime, Mackly
• Application Number:
  US09/328,402
• Time in Patent Office: 1,133 Days
• Field of Search: 345/157, 345/156, 345/158, 345/173, 345/175, 345/857, 345/862, 178/18.09
• US Class Current: 345/157
• CPC Class Codes: G06F 3/011 Arrangements for interaction with the human body, e.g. for user immersion in virtual reality blind teaching G09B21/00
• CPC Class Codes: G06F 3/0428 by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421
• CPC Class Codes: G06F 3/04842 Selection of displayed objects or displayed text elements G06F3/0482 takes precedence
• CPC Class Codes: G06F 3/04845 for image manipulation, e.g. dragging, rotation, expansion or change of colour

Abstract

The coordinate-position inputting/detecting device comprises a lighting device for emitting light into an entry area into which an arbitrary pointing body is inserted to perform an entry operation. At least two image pickup devices are provided with a prespecified space therebetween on a peripheral section of the entry area for picking up images of the pointing body illuminated by the light from the lighting device. Position on the CCD of the image pickup devices where an image of the pointing body is formed is obtained according to output from each of the image pickup devices. Coordinates of the position of the pointing body in the entry area are calculated from these positions.

Claims

1. A coordinate-position inputting/detecting device comprising:

at least two image pickup elements provided with a prespecified space therebetween on a peripheral section of an entry area, the at least two image pickup elements each providing an output indicating a portion of each of the at least two image pickup elements receiving an illuminated image of a pointing body inserted into said entry area to perform an entry operation;

coordinate-value identifying means for computing positions where each illuminated image is formed on each of said at least two image pickup elements according to each corresponding output from said at least two image pickup elements and for identifying coordinates of a position of said pointing body by using the computed positions;

storing means for storing the coordinates first identified by said coordinate-value identifying means as first coordinates;

determining means for determining whether the first coordinates stored in said storing means are coincident with updated coordinates newly identified by said coordinate-value identifying means or not; and

updating means for replacing the first coordinates stored in said storing means with said updated coordinates and outputting the updated coordinates when it is determined by said determining means that the first coordinates and the updated coordinates are not coincident, while abandoning the updated coordinates when it is determined by said determining means that the first coordinates and the updated coordinates are coincident and are continuously identified as being coincident over a prespecified period of time.

2. A coordinate-position inputting/detecting device according to claim 1 further comprising distortion correcting means for electrically correcting optical distortion of each illuminated image formed on each of said at least two image pickup elements.

3. A coordinate-position inputting/detecting device according to claim 1 further comprising pattern recognizing means for recognizing patterns according to each output from each of the at least two image pickup elements when a plurality of pointing bodies, each having a different pattern provided thereon, are inserted into said entry area.

4. A coordinate-position inputting/detecting device comprising:

light emitting means provided at a first location for emitting light into an entry area;

at least two image pickup elements that are positioned to be remote from the first location and provided with a prespecified space therebetween on a peripheral section of said entry area and with an orientation so that each of the at least two image pickup elements receives illuminated images made up of light reflected from a pointing body inserted into the entry area and illuminated by the light emitted from said light emitting means;

coordinate-value identifying means receiving an output from each of the at least two image pickup elements resulting from corresponding illuminated images made up of light reflected from the pointing body impinging thereon and using each of the outputs for computing corresponding positions where the illuminated images of said pointing body are formed on corresponding ones of said at least two image pickup elements, and for identifying coordinates of a position of said pointing body by using the computed positions;

storing means for storing the coordinates first identified by said coordinate-value identifying means as first coordinates;

determining means for determining whether the first coordinates stored in said storing means are coincident with updated coordinates newly identified by said coordinate-value identifying means or not; and

updating means for replacing the first coordinates stored in said storing means with said updated coordinates and outputting the updated coordinates when it is determined by said determining means that the first coordinates and the updated coordinates are not coincident, while abandoning the updated coordinates when it is determined by said determining means that the first coordinates and the updated coordinates are coincident and are continuously identified as being coincident over a prespecified period of time.

5. A coordinate-position inputting/detecting device according to claim 4;

wherein said light emitting means and said at least two image pickup elements are all positioned on a same side of the entry area.

6. A coordinate-position inputting/detecting device according to claim 4;

wherein said light emitting means has incident light preventing means for preventing the emitted light from the light emitting means from directly entering into each of said at least two image pickup elements.

7. A coordinate-position inputting/detecting device according to claim 4;

wherein said light emitting means has at least a light source for emitting light; and

a mirror for reflecting the light from the light source thereon and diffusing the light along said entry area.

8. A coordinate-position inputting/detecting device according to claim 7 further comprising adjusting means for changing an angle of said mirror to adjust a direction of reflecting the light.

9. A coordinate-position inputting/detecting device according to claim 8;

wherein said adjusting means comprises;

a light receiving element for receiving the light reflected by said mirror;

driving means for changing the angle of said mirror; and

control means for controlling said driving means in order to change the angle of said mirror according to intensity of the light received by said light receiving element.

10. A coordinate-position inputting/detecting device according to claim 4 further comprising reflection preventing means for preventing light emitted from said light emitting means and passing through the entry area from being reflected back into the entry area.

11. A coordinate-position inputting/detecting device according to claim 4 further comprising distortion correcting means for electrically correcting optical distortion of the illuminated images formed on each of said at least two image pickup elements.

12. A coordinate-position inputting/detecting device according to claim 4 further comprising pattern recognizing means for recognizing patterns according to each output from each of the at least two image pickup elements when a plurality of pointing bodies, each having a different pattern provided thereon, are inserted into said entry area.

13. A coordinate-position inputting/detecting device according to claim 4 further comprising a width identifying means for identifying a width of said pointing body according to the illuminated images formed on each of the at least two image pickup elements.

14. A coordinate-position inputting/detecting device according to claim 13 further comprising correcting means for correcting the coordinates identified by said coordinate-value identifying means using the width identified by said width identifying means.

15. A coordinate-position inputting/detecting device comprising:

at least two image pickup elements provided with a prespecified space therebetween on a peripheral section of an entry area into which an arbitrary pointing body is inserted to perform an entry operation;

first storing means for storing therein images of said entry area previously picked up by each of said at least two image pickup elements as corresponding reference images;

extracting means for extracting differential images of the arbitrary pointing body inserted into said entry area from corresponding present images of said entry area picked up by each of said at least two image pickup elements when the arbitrary pointing body is inserted into the entry area by obtaining a difference between each of the corresponding present images and a corresponding one of said reference images; and

coordinate-value identifying means for computing positions where each extracted differential image of said arbitrary pointing body is formed on each corresponding one of said image pickup elements, and for identifying coordinates of a position of said arbitrary pointing body by using the computed positions.

16. A coordinate-position inputting/detecting device according to claim 15 further comprising a background plate provided at a location which is on a peripheral section of said entry area included in a field of view of each of said at least two image pickup elements.

17. A coordinate-position inputting/detecting device according to claim 16;

wherein said background plate has an arbitrary pattern provided thereto.

18. A coordinate-position inputting/detecting device according to claim 15 further comprising area restricting means for restricting an imaging area covered by each of said at least two image pickup elements so that the imaging area covered is adjusted to said entry area.

19. A coordinate-position inputting/detecting device according to claim 15 further comprising:

second storing means for storing therein the coordinates first identified by said coordinate-value identifying means as first coordinates;

determining means for determining whether the first coordinates stored in said second storing means are coincident with updated coordinates newly identified by said coordinate-value identifying means or not; and

updating means for replacing the first coordinates stored in said second storing means with said updated coordinates and outputting the updated coordinates to an external device when it is determined by said determining means that the first coordinates and the updated coordinates are not coincident, while abandoning the updated coordinates when it is determined by said determining means that the first coordinates and the updated coordinates are coincident and are continuously identified as being coincident over a prespecified period of time.

20. A coordinate-position inputting/detecting device according to claim 19 further comprising image updating means for storing each image of said entry area used for identifying the coordinates of the position abandoned by said updating means in to said first storing means as a new reference image.

21. A coordinate-position inputting/detecting device comprising:

at least two image pickup elements provided with a prespecified space therebetween on a peripheral section of an entry area, the at least two image pickup elements being configured to provide an output indicating a portion of each of the at least two image pickup elements receiving an illuminated image of a pointing body inserted into said entry area to perform an entry operation; and

a coordinate-value identifying unit configured to compute positions where each illuminated image is formed on each of said at least two image pickup elements according to each corresponding output from said at least two image pickup elements, and further configured to identify coordinates of a position of said pointing body by using the computed positions,

wherein the coordinate-value identifying unit further comprises,

a store configured to store the coordinates first identified by said coordinate-value identifying unit as first coordinates,

a determining unit configured to determine whether the first coordinates stored in said store are coincident with updated coordinates newly identified by said coordinate-value identifying unit or not, and

an updating unit configured to replace the first coordinates stored in said store with said updated coordinates and outputting the updated coordinates when it is determined by said determining unit that the first coordinates and the updated coordinates are not coincident, while abandoning the updated coordinates when it is determined by said determining unit that the first coordinates and the updated coordinates are coincident and are continuously identified as being coincident over a prespecified period of time.

22. A coordinate-position inputting/detecting device comprising:

a light emitting element provided at a first location and configured to emit light into an entry area;

at least two image pickup elements that are positioned to be remote from the first location and provided with a prespecified space therebetween on a peripheral section in part defining said entry area and with an orientation so that each of the at least two image pickup elements receives illuminated images made up of light reflected from a pointing body inserted into the entry area and illuminated by the light emitted from said light emitting element; and

a coordinate-value identifying unit configured to receive an output from each of the at least two image pickup elements resulting from corresponding illuminated images made up of light reflected from the pointing body impinging thereon and using each of the outputs for computing corresponding positions where the illuminated images are formed on corresponding ones of said at least two image pickup means, and further configured to identify coordinates of a position of said pointing body by using the computed positions,

wherein the coordinate-value identifying unit further comprises,

a store configured to store the coordinates first identified by said coordinate-value identifying unit as first coordinates,

a determining unit configured to determine whether the first coordinates stored in said store are coincident with updated coordinates newly identified by said coordinate-value identifying unit or not, and

an updating unit configured to replace the first coordinates stored in said store with said updated coordinates and outputting the updated coordinates when it is determined by said determining unit that the first coordinates and the updated coordinates are not coincident, while abandoning the updated coordinates when it is determined by said determining unit that the first coordinates and the updated coordinates are coincident and are continuously identified as being coincident over a prespecified period of time.

23. A coordinate-position inputting/detecting device comprising:

at least two image pickup elements provided with a prespecified space therebetween on a peripheral section of an entry area into which an arbitrary pointing body is inserted to perform an entry operation;

a first memory for storing therein images of said entry area previously picked up by each of said at least two image pickup elements as corresponding reference images;

an extracting unit configured to extract differential images of the arbitrary pointing body inserted into said entry area from corresponding present images of said entry area picked up by each of said at least two image pickup elements when the arbitrary pointing body is inserted into the entry area by obtaining a difference between each of the corresponding present images and a corresponding one of said reference images; and

a coordinate-value identifying unit configured to compute positions where each extracted differential image of said pointing body is formed on each corresponding one of said image pickup elements, and further configured to identify coordinates of a position of said pointing body by using the computed positions.

24. A coordinate-position inputting/detecting method comprising the steps of:

obtaining an illuminated image of an arbitrary pointing body inserted into an entry area on each of at least two image pickup elements provided with a prespecified space therebetween on a peripheral section of the entry area;

providing an output from each of the at least two image pickup elements that indicates a portion on the corresponding one of the at least two image pickup elements having the corresponding illuminated image formed thereon;

computing positions where each of the illuminated images are formed on a corresponding one of said at least two image pickup elements according to each output; and

identifying coordinates of a position of said arbitrary pointing body in the entry area from the computed positions,

wherein said step of identifying coordinates further comprises,

storing an indication of the coordinates initially identified in a store,

determining whether or not the stored initially identified coordinates are coincident with updated coordinates later identified, and

replacing the indication of the coordinates as initially identified in the store with said updated coordinates and outputting the updated coordinates when it is determined by said determining step that the stored initially identified coordinates and the updated coordinates are not coincident, while abandoning the updated coordinates when it is determined by said determining step that the stored initially identified coordinates and the updated coordinates are coincident and are continuously identified as being coincident over a prespecified period of time.

25. A coordinate-position inputting/detecting method comprising the steps of:

emitting light into an entry area from a first location;

inserting a pointing body into the entry area to intercept and reflect the light to provide an entry operation;

obtaining an image of the pointing body in the form of the light reflected from the pointing body on each one of at least two image pickup elements provided with a prespecified space therebetween on a peripheral section of the entry area at two different locations remote from the first location;

providing an output from each of the at least two image pickup elements that indicates where on the corresponding one of the at least two image pickup elements the corresponding image of the pointing body is formed;

computing positions where each corresponding image of said pointing body is formed on each of said image pickup elements according to each output; and

identifying coordinates of a position of said pointing body in the entry area from the computed positions,

wherein said step of identifying coordinates further comprises,

storing an indication of the coordinates initially identified in a store,

determining whether or not the stored initially identified coordinates are coincident with updated coordinates later identified, and

replacing the indication of the coordinates as initially identified in the store with said updated coordinates and outputting the updated coordinates when it is determined by said determining step that the stored initially identified coordinates and the updated coordinates are not coincident, while abandoning the updated coordinates when it is determined by said determining step that the stored initially identified coordinates and the updated coordinates are coincident and are continuously identified as being coincident over a prespecified period of time.

26. A coordinate-position inputting/detecting method comprising the steps of:

providing at least two image pickup elements on a peripheral section of an entry area that are spaced apart by a predetermined distance;

obtaining corresponding reference images of said entry area as viewed from each of the at least two image pickup elements;

inserting a pointing body into the entry area;

forming corresponding entry images of the entry area containing the inserted pointing body using each of the at least two image pickup elements;

extracting corresponding differential images of the pointing body by determining differences between the corresponding entry images and the corresponding reference images;

computing positions where each of the corresponding differential images of said pointing body is formed on each of said at least two image pickup elements; and

identifying coordinates of a position of said pointing body in the entry area from the computed positions.

27. A display board system comprising at least:

display means for displaying characters and images;

a coordinate-position inputting/detecting device with an entry area provided in front of said display means; and

control means for providing controls over display by said display means according to input from said coordinate-position inputting/detecting device,

wherein the display means forms a display surface and the coordinate-position inputting/detecting device forms a writing surface of a display board and said coordinate-position inputting/detecting device comprises,

at least two image pickup elements provided with a prespecified space therebetween on a peripheral section of an entry area into which a pointing body is inserted to perform an entry operation including forming illuminated images of the pointing body inserted into said entry area on a portion of each of the at least two image pickup elements with each of the at least two image pickup elements providing an output corresponding to the portion of each that the illuminated images are formed on,

coordinate-value identifying means for computing positions where the illuminated images of said pointing body are formed according to each output from each of the at least two image pickup elements, and for identifying coordinates of a position of said pointing body by using the computed positions,

storing means for storing the coordinates first identified by said coordinate-value identifying means as first coordinates,

determining means for determining whether the first coordinates stored in said storing means are coincident with updated coordinates newly identified by said coordinate-value identifying means or not, and

updating means for replacing the first coordinates stored in said storing means with said updated coordinates and outputting the updated coordinates when it is determined by said determining means that the first coordinates and the updated coordinates are not coincident, while abandoning the updated coordinates when it is determined by said determining means that the first coordinates and the updated coordinates are coincident and are continuously identified as being coincident over a prespecified period of time.

28. A display board system according to claim 27;

wherein said display means is a plasma display.

29. A display board system according to claim 27;

wherein said display means further has a plurality of connecting means for connecting various types of information equipment including video equipment, and is usable as a large-sized screen monitor using said connecting means.

30. A display board system comprising at least:

display means for displaying characters and images;

a coordinate-position inputting/detecting device with an entry area provided in front of said display means; and

control means for providing controls over display by said display means according to input from said coordinate-position inputting/detecting device,

wherein the display means forms a display surface and the coordinate-position inputting/detecting device forms a writing surface of a display board and said coordinate-position inputting/detecting device comprises,

light emitting means at a first location for emitting light into an entry area into which a pointing body is inserted to perform an entry operation,

at least two image pickup elements located remotely from the first location and provided with a prespecified space therebetween on a peripheral section of said entry area for picking up illuminated images of said pointing body illuminated by the light emitted from said light emitting means, with each of the at least two image pickup elements providing an output corresponding to the illuminated images formed thereon,

coordinate-value identifying means for computing positions where the illuminated images of said pointing body are formed on each of the at least two image pickup elements according to each output from the at least two image pickup elements, and for identifying coordinates of a position of said pointing body by using the computed positions,

storing means for storing the coordinates first identified by said coordinate-value identifying means as first coordinates,

determining means for determining whether the first coordinates stored in said storing means are coincident with updated coordinates newly identified by said coordinate-value identifying means or not, and

updating means for replacing the first coordinates stored in said storing means with said updated coordinates and outputting the updated coordinates when it is determined by said determining means that the first coordinates and the updated coordinates are not coincident, while abandoning the updated coordinates when it is determined by said determining means that the first coordinates and the updated coordinates are coincident and are continuously identified as being coincident over a prespecified period of time.

31. A display board system according to claim 30;

wherein said display means is a plasma display.

32. A display board system according to claim 30;

wherein said display means further has a plurality of connecting means for connecting various types of including video equipment, and is usable as a large-sized screen monitor using said connecting means.

33. A display board system comprising at least:

display means for displaying characters and images;

a coordinate-position inputting/detecting device with an entry area provided in front of said display means; and

control means for providing controls over display by said display means according to input from said coordinate-position inputting/detecting device,

wherein the display means forms a display surface and the coordinate-position inputting/detecting device forms a writing surface of a display board and said coordinate-position inputting/detecting device comprises,

at least two image pickup elements provided with a prespecified space therebetween on a peripheral section of an entry area into which a pointing body is inserted to perform an entry operation for picking up images of the pointing body,

first storing means for storing therein images of said entry area previously picked up by each of the at least two image pickup elements as corresponding reference images,

extracting means for extracting differential images of the pointing body inserted into said entry area from corresponding present images of said entry area picked up by each of the at least two image pickup elements when the pointing body is inserted into the entry area by obtaining a difference between each of the corresponding present images and a corresponding one of said reference images; and

coordinate-value identifying means for computing positions where each extracted differential image of said pointing body is formed on each corresponding one of the image pickup elements, and identifying coordinates of a position of said pointing body by using the computed positions.

34. A display board system according to claim 33;

wherein said display means is a plasma display.

35. A display board system according to claim 33;

wherein said display means further has a plurality of connecting means for connecting various types of information equipment including video equipment, and is usable as a large-sized screen monitor using said connecting means.

36. A display board system comprising at least:

display means for displaying characters and images;

a coordinate-position inputting/detecting device with an entry area provided in front of said display means;

printing means for outputting image data onto a recording paper; and

control means for providing controls over the display by said display means as well as over printing operations by said printing means according to input from said coordinate-position inputting/detecting device,

wherein the display means forms a display surface and the coordinate-position inputting/detecting device forms a writing surface of the display board and said coordinate-position inputting/detecting device comprises,

at least two image pickup elements provided with a prespecified space therebetween on a peripheral section of an entry area, the at least two image pickup elements each providing an output indicating a portion of each of the at least two image pickup elements receiving an illuminated image of a pointing body inserted into said entry area to perform an entry operation,

coordinate-value identifying means for computing positions where each illuminated image is formed on each of the at least two image pickup elements according to each corresponding output from the at least two image pickup elements, and for identifying coordinates of a position of said pointing body by using the computed positions,

storing means for storing the coordinates first identified by said coordinate-value identifying means as first coordinates,

determining means for determining whether the first coordinates stored in said storing means are coincident with updated coordinates newly identified by said coordinate-value identifying means or not, and

updating means for replacing the first coordinates stored in said storing means with said updated coordinates and outputting the updated coordinates when it is determined by said determining means that the first coordinates and the updated coordinates are not coincident, while abandoning the updated coordinates when it is determined by said determining means that the first coordinates and the updated coordinates are coincident and are continuously identified as being coincident over a prespecified period of time;

and further wherein said control means is a personal computer and said display board system further comprises,

a frame unit having holding means for holding the display surface and the writing surface of the display board at a specified height,

a printer accommodating means for accommodating said printing means therein, and

control accommodating means for accommodating said control means therein,

wherein said control accommodating means and said printer accommodating means are arranged in the frame unit beneath the holding means.

37. A display board system according to claim 36;

wherein said display means is a plasma display.

38. A display board system according to claim 36;

wherein said frame unit has a keyboard placement means provided at a position on the upper side of said printer accommodating means but on the lower side of said holding means for placing a keyboard connected to said personal computer.

39. A display board system according to claim 36;

wherein said holding means includes an angle adjusting means for adjusting an angle of the display surface and the writing surface of the display board.

40. A display board system according to claim 36;

wherein said display means further has a plurality of connecting means for connecting various types of information equipment including video equipment, and is usable as a large-sized screen monitor using said connecting means.

41. A display board system comprising at least:

display means for displaying characters and images;

a coordinate-position inputting/detecting device with an entry area provided in front of said display means;

printing means for outputting image data onto a recording paper; and

control means for providing controls over the display by said display means as well as over printing operations by said printing means according to input from said coordinate-position inputting/detecting device,

wherein the display means forms a display surface and the coordinate-position inputting/detecting device forms a writing surface of the display board and said coordinate-position inputting/detecting device comprises,

light emitting means for emitting light into an entry area,

at least two image pickup elements provided with a prespecified space therebetween on a peripheral section of said entry area for picking up illuminated images made up of light reflected from a pointing body inserted into the entry area and illuminated by the light emitted from said light emitting means, and

coordinate-value identifying means receiving an output from each of the at least two image pickup elements resulting from corresponding illuminated images made up of light reflected from the pointing body impinging thereon and using each of the outputs for computing corresponding positions where the illuminated images of said pointing body are formed on corresponding ones of the at least two image pickup elements, and for identifying coordinates of a position of said pointing body by using the computed positions,

storing means for storing the coordinates first identified by said coordinate-value identifying means as first coordinates,

determining means for determining whether the first coordinates stored in said storing means are coincident with updated coordinates newly identified by said coordinate-value identifying means or not, and

updating means for replacing the first coordinates stored in said storing means with said updated coordinates and outputting the updated coordinates when it is determined by said determining means that the first coordinates and the updated coordinates are not coincident, while abandoning the updated coordinates when it is determined by said determining means that the first coordinates and the updated coordinates are coincident and are continuously identified as being coincident over a prespecified period of time,

and further wherein said control means is a personal computer and said display board system further comprises,

a frame unit having holding means for holding the display surface and the writing surface of the display board at a specified height,

a printer accommodating means for accommodating said printing means therein, and

control accommodating means for accommodating said control means therein,

wherein said control accommodating means and said printer accommodating means are arranged in the frame unit beneath the holding means.

42. A display board system according to claim 41;

wherein said display means is a plasma display.

43. A display board system according to claim 41;

wherein said frame unit has a keyboard placement means provided at a position on the upper side of said printer accommodating means but on the lower side of said holding means for placing a keyboard connected to said personal computer.

44. A display board system according to claim 41;

wherein said holding means includes an angle adjusting means for adjusting an angle of the display surface and the writing surface of the display board.

45. A display board system according to claim 41;

wherein said display means further has a plurality of connecting means for connecting various types of information equipment including video equipment, and is usable as a large-sized screen monitor using said connecting means.

46. A display board system comprising at least:

display means for displaying characters and images;

a coordinate-position inputting/detecting device with an entry area provided in front of said display means;

printing means for outputting image data onto a recording paper; and

control means for providing controls over the display by said display means as well as over printing operations by said printing means according to input from said coordinate-position inputting/detecting device,

wherein the display means forms a display surface and the coordinate-position inputting/detecting device forms a writing surface of the display board and said coordinate-position inputting/detecting device comprises,

at least two image pickup elements provided with a prespecified space therebetween on a peripheral section of an entry area into which an arbitrary pointing body is inserted to perform an entry operation,

first storing means for storing therein images of said entry area previously picked up by each of the at least two image pickup elements as corresponding reference images,

extracting means for extracting differential images of the arbitrary pointing body inserted into said entry area from corresponding present images of said entry area picked up by each of the at least two image pickup elements when the arbitrary pointing body is inserted into the entry area by obtaining a difference between each of the corresponding present images and a corresponding one of said reference images,

coordinate-value identifying means for computing positions where each extracted differential image of said arbitrary pointing body is formed on each corresponding one of the image pickup elements, and for identifying coordinates of a position of said arbitrary pointing body by using the computed positions,

and further wherein said control means is a personal computer and said display board system further comprises,

a frame unit having holding means for holding the display surface and the writing surface of the display board at a specified height,

a printer accommodating means for accommodating said printing means therein, and

control accommodating means for accommodating said control means therein,

wherein said control accommodating means and said printer accommodating means are arranged in the frame unit beneath the holding means.

47. A display board system according to claim 46;

wherein said display means is a plasma display.

48. A display board system according to claim 46;

wherein said frame unit has a keyboard placement means provided at a position on the upper side of said printer accommodating means but on the lower side of said holding means for placing a keyboard connected to said personal computer.

49. A display board system according to claim 46;

wherein said holding means includes an angle adjusting means for adjusting an angle of the display surface and the writing surface of the display board.

50. A display board system according to claim 46;

wherein said display means further has a plurality of connecting means for connecting various types of information equipment including video equipment, and is usable as a large-sized screen monitor using said connecting means.