Optical coordinate input/detection device with optical-unit positioning error correcting function

• US 20010019325A1
• Filed: 03/06/2001
• Published: 09/06/2001
• Est. Priority Date: 03/06/2000
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Takekawa, Kenichi
• Granted Patent: US 6,823,481 B2
• Time in Patent Office: Days
• US Class Current: 345/157
• CPC Class Codes: G06F 3/0423 using sweeping light beams, e.g. using rotating or vibrating mirror

Abstract

A coordinate input/detection device compares a waveform of a signal corresponding to intensity distribution of rays received from a coordinate input area by a light-receiving unit and a standard waveform at fixed timing. If the waveform is not equal to the standard waveform, the coordinate input/detection device determines that an installation position of the light-receiving unit is off a correct position because of shock or vibration, and obtains a new standard waveform and stores the new standard waveform in a storage unit, thereby setting the waveform of the signal corresponding to the intensity distribution of rays received by the light-receiving unit located at an incorrect position as the standard waveform. Accordingly, there is no error in relative positions of a peak point corresponding to a standard mark, that is, a standard for detecting coordinates of a pointing instrument in the coordinate input area, and a peak point corresponding to the pointing instrument in the intensity distribution, thereby preventing misdetection of the coordinates.

Claims

1. A coordinate input/detection device provided with a coordinate input area, comprising:

a light-emitting unit emitting a plurality of rays to the coordinate input area;

a light-receiving unit receiving said plurality of rays reflected by sides of the coordinate input area, and obtaining intensity distribution of said plurality of rays;

a coordinate detection unit detecting coordinates of a pointing instrument inserted to the coordinate input area, based on the intensity distribution;

a standard mark provided at a fixed position in the coordinate input area so that said light-receiving unit generates a peak intensity corresponding to a ray reflected at said standard mark in the intensity distribution; and

an error detection unit detecting a positioning error of said light-receiving unit by detecting a shift in a position of the peak intensity in the intensity distribution at fixed timing.

2. The coordinate input/detection device as claimed in

claim 1

, wherein said fixed timing is timing at which a fixed period has passed being in a condition that said coordinate detection unit does not detect the coordinates.

3. The coordinate input/detection device as claimed in

claim 1

, further comprising a notification unit notifying the positioning error of said light-receiving unit to a user if the position of said peak intensity changes in the intensity distribution.

4. A coordinate input/detection device provided with a coordinate input area, comprising:

a light-emitting unit emitting a plurality of rays to the coordinate input area;

a light-receiving unit receiving said plurality of rays reflected by sides of the coordinate input area, thereby obtaining intensity distribution of said plurality of rays, and outputting a signal corresponding to the intensity distribution;

a standard mark provided at a fixed position in the coordinate input area so that said light-receiving unit generates a peak intensity corresponding to a ray reflected at said standard mark in the intensity distribution;

a coordinate detection unit detecting coordinates of a pointing instrument inserted to the coordinate input area, in accordance with a position of said peak intensity in the intensity distribution;

a storage unit;

a standard-waveform storing unit storing a first waveform of the signal including the peak point as a standard waveform in said storage unit;

a waveform comparing unit comparing a second waveform of the signal with said standard waveform at fixed timing,

wherein said standard-waveform storing unit stores a new waveform of the signal outputted by said light-receiving unit as the standard waveform in said storage unit in a case in which said second waveform is not equal to said standard waveform.

5. The coordinate input/detection device as claimed in

claim 4

, wherein said fixed timing is timing at which a fixed period has passed being in a condition that said coordinate detection unit does not detect the coordinates.

6. The coordinate input/detection device as claimed in

claim 4

, further comprising a notification unit notifying the positioning error of said light-receiving unit to a user if said waveform comparing unit detects that said second waveform does not include the peak point included in said standard waveform.

7. The coordinate input/detection device as claimed in

claim 4

, wherein said sides of the coordinate input area are made of retro-reflecting material.

8. The coordinate input/detection device as claimed in

claim 4

, wherein said pointing instrument and said standard mark are made of retro-reflecting material.

9. An electronic blackboard system comprising:

an electronic blackboard unit whose displaying surface and writing surface include a displaying unit and a coordinate input/detection unit respectively; and

a control unit executing a displaying control of said displaying unit based on a signal outputted from said coordinate input/detection unit,

wherein said coordinate input/detection unit includes a coordinate input area corresponding to a displaying surface of said displaying unit;

a light-emitting unit emitting a plurality of rays to the coordinate input area;

a light-receiving unit receiving said plurality of rays reflected by sides of the coordinate input area, thereby obtaining intensity distribution of said plurality of rays, and outputting the signal corresponding to the intensity distribution;

a standard mark provided at a fixed position in the coordinate input area so that said light-receiving unit generates a peak intensity corresponding to a ray reflected at said standard mark in the intensity distribution;

a coordinate detection unit detecting coordinates of a pointing instrument inserted to the coordinate input area, in accordance with a position of said peak intensity in the intensity distribution;

a storage unit;

a standard-waveform storing unit storing a first waveform of the signal including the peak point as a standard waveform in said storage unit;

a waveform comparing unit comparing a second waveform of the signal with said standard waveform at fixed timing, wherein said standard-waveform storing unit stores a new waveform of the signal outputted by said light-receiving unit as the standard waveform in said storage unit in a case in which said second waveform is not equal to said standard waveform.

10. An electronic blackboard system comprising:

an electronic blackboard unit whose writing surface includes a writing board to which handwriting information is inputted, and a coordinate input/detection unit; and

a control unit controlling the handwriting information inputted to said writing board based on a signal outputted from said coordinate input/detection unit,

wherein said coordinate input/detection unit includes a coordinate input area corresponding to a writing surface of said writing board;

a light-emitting unit emitting a plurality of rays to the coordinate input area;

a light-receiving unit receiving said plurality of rays reflected by sides of the coordinate input area, thereby obtaining intensity distribution of said plurality of rays, and outputting the signal corresponding to the intensity distribution;

a standard mark provided at a fixed position in the coordinate input area so that said light-receiving unit generates a peak intensity corresponding to a ray reflected at said standard mark in the intensity distribution;

a coordinate detection unit detecting coordinates of a pointing instrument inserted to the coordinate input area, in accordance with a position of said peak intensity in the intensity distribution;

a storage unit;

a standard-waveform storing unit storing a first waveform of the signal including the peak point as a standard waveform in said storage unit;

a waveform comparing unit comparing a second waveform of the signal with said standard waveform at fixed timing, wherein said standard-waveform storing unit stores a new waveform of the signal outputted by said light-receiving unit as the standard waveform in said storage unit in a case in which said second waveform is not equal to said standard waveform.

11. A method of detecting a positioning error of a light-receiving unit included in a coordinate input/detection device provided with a coordinate input area, said coordinate input/detection device including a light-emitting unit emitting a plurality of rays to the coordinate input area;

said light-receiving unit receiving said plurality of rays reflected by sides of the coordinate input area, and obtaining intensity distribution of said plurality of rays;

a coordinate detection unit detecting coordinates of a pointing instrument inserted to the coordinate input area, based on the intensity distribution; and

a standard mark provided at a fixed position in the coordinate input area so that said light-receiving unit generates a peak intensity corresponding to a ray reflected at said standard mark in the intensity distribution, said method comprising the step of detecting the positioning error of said light-receiving unit by detecting a shift in a position of the peak intensity in the intensity distribution at fixed timing.

12. The method as claimed in

claim 11

, wherein said fixed timing is timing at which a fixed period has passed being in a condition that said coordinate detection unit does not detect the coordinates.

13. The method as claimed in

claim 11

, further comprising the step of notifying the positioning error of said light-receiving unit to a user if the position of said peak intensity changes in the intensity distribution.

14. A method of correcting a positioning error of a light-receiving unit included in a coordinate input/detection device provided with a coordinate input area, said coordinate input/detection device including a light-emitting unit emitting a plurality of rays to the coordinate input area;

said light-receiving unit receiving said plurality of rays reflected by sides of the coordinate input area, thereby obtaining intensity distribution of said plurality of rays, and outputting a signal corresponding to the intensity distribution;

a standard mark provided at a fixed position in the coordinate input area so that said light-receiving unit generates a peak intensity corresponding to a ray reflected at said standard mark in the intensity distribution;

a coordinate detection unit detecting coordinates of a pointing instrument inserted to the coordinate input area, in accordance with a position of said peak intensity in the intensity distribution; and

a storage unit, said method comprising the steps of;

storing a first waveform of the signal including the peak point as a standard waveform in said storage unit;

comparing a second waveform of the signal with said standard waveform at fixed timing; and

storing a new waveform of the signal outputted by said light-receiving unit as the standard waveform in said storage unit in a case in which said second waveform is not equal to said standard waveform.

15. The method as claimed in

claim 14

, wherein said fixed timing is timing at which a fixed period has passed being in a condition that said coordinate detection unit does not detect the coordinates.

16. The method as claimed in

claim 14

, further comprising the step of notifying the positioning error of said light-receiving unit to a user in a case of detecting that said second waveform does not include the peak point included in said standard waveform.

17. A recording medium readable by a coordinate input/detection device, tangibly embodying a program of instructions executable by the coordinate input/detection device to correct a positioning error of a light-receiving unit included in the coordinate input/detection device provided with a coordinate input area, said coordinate input/detection device including a light-emitting unit emitting a plurality of rays to the coordinate input area;

said light-receiving unit receiving said plurality of rays reflected by sides of the coordinate input area, thereby obtaining intensity distribution of said plurality of rays, and outputting a signal corresponding to the intensity distribution;

a standard mark provided at a fixed position in the coordinate input area so that said light-receiving unit generates a peak intensity corresponding to a ray reflected at said standard mark in the intensity distribution;

a coordinate detection unit detecting coordinates of a pointing instrument inserted to the coordinate input area, in accordance with a position of said peak intensity in the intensity distribution; and

a storage unit, said program including the steps of;

storing a first waveform of the signal including the peak point as a standard waveform in said storage unit;

comparing a second waveform of the signal with said standard waveform at fixed timing; and

storing a new waveform of the signal outputted by said light-receiving unit as the standard waveform in said storage unit in a case in which said second waveform is not equal to said standard waveform.

18. The recording medium as claimed in

claim 17

, wherein said fixed timing is timing at which a fixed period has passed being in a condition that said coordinate detection unit does not detect the coordinates.

19. The recording medium as claimed in

claim 17

, wherein said program further comprising the step of notifying the positioning error of said light-receiving unit to a user in a case of detecting that said second waveform does not include the peak point included in said standard waveform.