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

• US 6,906,702 B1
• Filed: 03/16/2000
• Issued: 06/14/2005
• 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:
  US09/526,463
• Time in Patent Office: 1,916 Days
• Field of Search: 345173-179, 178 1801- 1807, 178 1901- 1905, 178/18.09
• US Class Current: 345/175
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/0386 for light pen
• 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 plurality of linear sensors which are arranged for at least one coordinate axis and detect the beam spot. The levels of detected data are measured by a sensor controller, and the measured levels are compared. Based on the comparison result, the detection result of one of the plurality of linear sensors is selected. A coordinate computation unit outputs a coordinate value corresponding to the beam spot on the basis of the selected detection result. The light-receiving areas of the linear sensors have an overlapping portion.

Claims

1. A coordinate input device for generating a coordinate value corresponding to light coming from a pointing tool, comprising:

optical means for imaging the light;

a plurality of sensing means, arranged for one coordinate axis, for sensing the light imaged by said optical means, wherein light-receiving areas of said plurality of sensing means have an overlapping portion;

measurement means for measuring peak levels of data sensed by said plurality of sensing means arranged for the one coordinate axis;

comparison means for comparing the peak levels measured by said measurement means;

selection means for selecting one of said plurality of sensing means arranged for the one coordinate axis on the basis of a comparison result of said comparison means; and

output means for outputting a coordinate value corresponding to the light on the basis of the sensing means selected by said selection means.

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

3. The device according to claim 2, wherein said output means comprises computation means for computing the coordinate value corresponding to the light at a resolving power not less than the number of pixels corresponding to said plurality of photoelectric conversion elements.

4. The device according to claim 1, wherein said output means comprises storage means for storing a reference coordinate value in the overlapping portion, and

said output means outputs the coordinate value corresponding to the light using the reference coordinate value.

5. The device according to claim 1, wherein the overlapping portion is defined by light-receiving areas of neighboring ones of said plurality of sensing means.

6. A method of controlling a coordinate input device for generating a coordinate value corresponding to light coming from a pointing tool, comprising the steps of:

measuring peak levels of data detected by a plurality of sensors, which are arranged for one coordinate axis and adapted to sense the light imaged by an optical means, wherein light-receiving areas of the plurality of sensors have an overlapping portion;

comparing the peak levels measured in the measurement step;

selecting one of the plurality of sensors arranged for the one coordinate axis on the basis of a comparison result in the comparison step; and

outputting a coordinate value corresponding to the light on the basis of the sensor selected in the selection step.

7. The method according to claim 6, wherein each of the plurality of sensors has a linear array of a plurality of photoelectric conversion elements.

8. The method according to claim 7, wherein the output step computes the coordinate value corresponding to the light at a resolving power not less than the number of pixels corresponding to the plurality of photoelectric conversion elements.

9. The method according to claim 6, wherein the output step stores a reference coordinate value in the overlapping portion in a storage medium, and

the output step outputs the coordinate value corresponding to the light using the reference coordinate value.

10. The method according to claim 6, wherein the overlapping portion is defined by light-receiving areas of neighboring ones of the plurality of sensors.

11. A computer readable memory which stores a program code of controlling a coordinate input device for generating a coordinate value corresponding to light coming from a pointing tool, comprising:

a program code of a measurement step of measuring peak levels of data detected by a plurality of sensors, which are arranged for one coordinate axis and adapted to sense the light imaged by an optical means, wherein the light-receiving areas of the plurality of sensors have an overlapping portion;

a program code of a comparison step of comparing the peak levels measured in the measurement step;

a program code of a selection step of selecting one of the plurality of sensors arranged for the one coordinate axis on the basis of a comparison result in the comparison step; and

a program code of an output step of outputting a coordinate value corresponding to the light on the basis of the sensor selected in the selection step.