Coordinate input device and its control method, and computer readable memory

• US 6,731,271 B1
• Filed: 03/16/2000
• Issued: 05/04/2004
• Est. Priority Date: 03/19/1999
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tanaka, Atsushi, Kobayashi, Katsuyuki, Kobayashi, Kiwamu, Hasegawa, Masahide, Kanashiki, Masaaki, Yoshimura, Yuichiro
• Primary Examiner(s): Shankar, Vijay
• Application Number:
  US09/526,464
• Time in Patent Office: 1,510 Days
• Field of Search: 345/173, 345/174, 345/175, 345/176, 345/179, 178/18.01, 178/18.03, 178/18.09, 178/18.06, 178/18.07, 178/19.01, 178/19.02, 178/19.03, 178/19.04, 178/19.07, 178/19.05
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0354 with detection of 2D relative movements between the device, or an operating part thereof, and a plane or surface, e.g. 2D mice, trackballs, pens or pucks
• CPC Class Codes: G06F 3/03542 Light pens for emitting or receiving light
• CPC Class Codes: G06F 3/0386 for light pen
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0425 using a single imaging device like a video camera for tracking the absolute position of a single or a plurality of objects with respect to an imaged reference surface, e.g. video camera imaging a display or a projection screen, a table or a wall surface, on which a computer generated image is displayed or projected tracking a projected light spot to determine a position on a display surface G06F3/0386

Abstract

A device has a light-receiving element for receiving light coming from a pointing tool, and a plurality of linear sensors for sensing a beam spot. A controller discriminates if a first signal output from the light-receiving element and a second signal output from the linear sensors are synchronized. A coordinate computation unit outputs a coordinate value corresponding to the beam spot on the basis of the discrimination result.

Claims

1. A coordinate input device for generating a light spot by irradiating a predetermined position of a coordinate input surface with light coming from a pointing tool, and generating a coordinate value corresponding to the light spot, comprising:

light-receiving means for receiving flickering light coming from the pointing tool for performing emission and non-emission;

sensing means for sensing the light spot;

synchronization discrimination means for discriminating if a first signal output from said light-receiving means and a second signal output from said sensing means are synchronized, wherein the first signal indicates emission and non-emission timings of the pointing tool and the second signal indicates detection timing of the emission and non-emission timings of the pointing tool; and

output means for outputting a coordinate value corresponding to the light spot on the basis of a discrimination result of said synchronization discrimination means,

wherein said synchronization discrimination means comprises detection means for detecting a synchronization state between the first and second signals within a predetermined period after initiation of a sampling period, and

said synchronization discrimination means discriminates on the basis of a detection result of said detection means if the first and second signals are synchronized.

2. The device according to claim 1, wherein when said synchronization discrimination means determines that the first and second signals are synchronized, said output means outputs the coordinate value corresponding to the light spot.

3. The device according to claim 1, wherein said sensing means comprises a linear array of a plurality of photoelectric conversion elements.

4. The device according to claim 3, wherein said output means comprises computation means for computing the coordinate value corresponding to the light spot at a resolving power not less than the number of pixels corresponding to the plurality of photoelectric conversion elements.

5. A coordinate input device for generating a light spot by irradiating a predetermined position of a coordinate input surface with light coming from a pointing tool, and generating a coordinate value corresponding to the light spot, comprising:

light-receiving means for receiving flickering light coming from the pointing tool for performing emission and non-emission;

sensing means for sensing the light spot;

synchronization discrimination means for discriminating if a first signal output from said light-receiving means and a second signal output from said sensing means are synchronized, wherein the first signal indicates emission and non-emission timings of the pointing tool and the second signal indicates detection timing of the emission and non-emission timings of the pointing tool; and

control means for controlling a clear timing of information sensed by said sensing means on the basis of a discrimination result of said synchronization discrimination means,

wherein said synchronization discrimination means comprises detection means for detecting a synchronization state between the first and second signals within a predetermined period after initiation of a sampling period, and

said synchronization discrimination means discriminates on the basis of a detection result of said detection means if the first and second signals are synchronized.

6. The device according to claim 5, wherein said control means outputs a predetermined signal to said sensing means on the basis of the discrimination result of said synchronization discrimination means.

7. The device according to claim 6, wherein said control means determines an output timing of the predetermined signal in accordance with a synchronization state between the first and second signals, which is discriminated by said synchronization discrimination means.

8. The device according to claim 6, wherein the predetermined signal instructs to clear sensing contents of said sensing means.

9. The device according to claim 5, further comprising output means for outputting a coordinate value corresponding to the light spot on the basis of a discrimination result of said synchronization discrimination means.

10. A method of controlling a coordinate input device for generating a light spot by irradiating a predetermined position of a coordinate input surface with light coming from a pointing tool, and generating a coordinate value corresponding to the light spot, comprising:

a light-receiving step of receiving flickering light coming from the pointing tool for performing emission and non-emission;

a sensing step of sensing the light spot using a sensor;

a synchronization discrimination step of discriminating if a first signal output in the light-receiving step and a second signal output from the sensor are synchronized, wherein the first signal indicates emission and non-emission timings of the pointing tool and the second signal indicates detection timing of the emission and non-emission timings of the pointing tool; and

an output step of outputting a coordinate value corresponding to the light spot on the basis of a discrimination result in the synchronization discrimination step,

wherein said synchronization discrimination step includes the steps of detecting a synchronization state between the first and second signals within a predetermined period after initiation of a sampling period, and discriminating on the basis of the detection if the first and second signals are synchronized.

11. The method according to claim 10, wherein the output step outputs the coordinate value corresponding to the light spot, when it is determined in the synchronization discrimination step that the first and second signals are synchronized.

12. The method according to claim 10, wherein the sensor comprises a linear array of a plurality of photoelectric conversion elements.

13. The method according to claim 10, wherein the output step comprises a computation step of computing the coordinate value corresponding to the light spot at a resolving power not less than the number of pixels corresponding to the plurality of photoelectric conversion elements.

14. A method of controlling a coordinate input device for generating a light spot by irradiating a predetermined position of a coordinate input surface with light coming from a pointing tool, and generating a coordinate value corresponding to the light spot, comprising:

a light-receiving step of receiving flickering light coming from the pointing tool for performing emission and non-emission;

a sensing step of sensing the light spot using a sensor;

a synchronization discrimination step of discriminating if a first signal output in the light-receiving step and a second signal output from the sensor are synchronized, wherein the first signal indicates emission and non-emission timings of the pointing tool and the second signal indicates detection timing of the emission and non-emission timings of the pointing tool; and

a control step of controlling a clear timing of information sensed by the sensor on the basis of a discrimination result in the synchronization discrimination step,

wherein said synchronization discrimination step includes the steps of detecting a synchronization state between the first and second signals within a predetermined period after initiation of a sampling period, and discriminating on the basis of the detection if the first and second signals are synchronized.

15. The method according to claim 14, wherein the control step outputs a predetermined signal to the detection unit on the basis of the discrimination result in the synchronization discrimination step.

16. The method according to claim 15, wherein the control step determines an output timing of the predetermined signal in accordance with a synchronization state between the first and second signals, which is discriminated in the synchronization discrimination step.

17. The method according to claim 15, wherein the predetermined signal instructs to clear sensing contents of the sensor.

18. The method according to claim 14, further comprising an output step of outputting a coordinate value corresponding to the light spot on the basis of a discrimination result in the synchronization discrimination step.

19. A computer readable memory which stores a program code of controlling a coordinate input device for generating a light spot by irradiating a predetermined position of a coordinate input surface with light coming from a pointing tool, and generating a coordinate value corresponding to the light spot, comprising:

a program code of a light-receiving step of receiving flickering light coming from the pointing tool for performing emission and non-emission;

a program code of a sensing step of sensing the light spot using a sensor;

a program code of a synchronization discrimination step of discriminating synchronization between a first signal output in the light-receiving step, and a second signal output from the sensor, wherein the first signal indicates emission and non-emission timings of the pointing tool and the second signal indicates detection timing of the emission and non-emission of the pointing tool; and

a program code of an output step of outputting a coordinate value corresponding to the light spot on the basis of a discrimination result in the synchronization discrimination step,

wherein said synchronization discrimination step includes the steps of detecting a synchronization state between the first and second signals within a predetermined period after initiation of a sampling period, and discriminating on the basis of the detection if the first and second signals are synchronized.

20. A computer readable memory which stores a program code of controlling a coordinate input device for generating a light spot by irradiating a predetermined position of a coordinate input surface with light coming from a pointing tool, and generating a coordinate value corresponding to the light spot, comprising:

a program code of a light-receiving step of receiving flickering light coming from the pointing tool for performing emission and non-emission;

a program code of a sensing step of sensing the light spot using a sensor;

a program code of a synchronization discrimination step of discriminating synchronization between a first signal output in the light-receiving step, and a second signal output from the sensor, wherein the first signal indicates emission and non-emission timings of the pointing tool and the second signal indicates detection timing of the emission and non-emission timings of the pointing tool; and

a program code of a control step of controlling a clear timing of information sensed by the sensor on the basis of a discrimination result in the synchronization discrimination step,

wherein said synchronization discrimination step includes the steps of detecting a synchronization state between the first and second signals within a predetermined period after initiation of a sampling period, and discriminating on the basis of the detection if the first and second signals are synchronized.