Coordinate input apparatus and control method and program therefor

• US 20020042699A1
• Filed: 07/06/2001
• Published: 04/11/2002
• Est. Priority Date: 07/07/2000
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tanaka, Atsushi, Kobayashi, Katsuyuki
• Granted Patent: US 6,900,791 B2
• Time in Patent Office: Days
• US Class Current: 703/2
• 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 light irradiated on a coordinate input screen from a pointing device is detected, and pieces of output information obtained as detection results for light at least at three known positions including first to third positions are stored. The coordinate values of the light formed on the coordinate input screen are calculated using at least two of the stored pieces of output information at the first to third positions.

Claims

1. A coordinate input apparatus for irradiating a coordinate input screen with light from a pointing device, and generating coordinates corresponding to the light, comprising:

detection means for detecting the light irradiated on the coordinate input screen from the pointing device;

storage means for storing output information from said detection means by light at least at three known positions including first to third positions; and

calculation means for calculating coordinate values of the light irradiated on the coordinate input screen using at least two of the pieces of output information at the first to third positions, which are stored in said storage means.

2. The apparatus according to claim 1, wherein said calculation means can execute first calculation for calculating the coordinate values of the light formed on the coordinate input screen using the output information at the first and second positions and second calculation for performing, for a result of the first calculation, correction calculation of the coordinate values of the light formed on the coordinate input screen using the output information at the third position.

3. The apparatus according to claim 2, wherein when coordinate values as the result of the first calculation are (X′

,Y′

), and coordinate values as a result of the second calculation are (X,Y), X is a dependent function of X′ and

Y′

, and Y is a dependent function of X′ and

Y′

.

4. The apparatus according to claim 2, further comprising determination means for determining on the basis of the result of the first calculation whether the second calculation is to be executed.

5. The apparatus according to claim 1, wherein the third position is at least one of four corners of a coordinate input effective area of the coordinate input screen.

6. The apparatus according to claim 1, wherein

said detection means comprises an X-axis sensor in which photosensitive portions are linearly arrayed in an X-axis direction and a Y-axis sensor in which photosensitive portions are linearly arrayed in a Y-axis direction,

an image of the light is formed on said X-axis sensor through a cylindrical lens having an axis in the Y-axis direction, and

the image of the light is formed on said Y-axis sensor through a cylindrical lens having an axis in the X-axis direction.

7. The apparatus according to claim 6, wherein the third position is set at a position in the coordinate input effective area, where an angle made by a light beam from an incident position on the cylindrical lens and a perpendicular to the photosensitive portions of said detection means is maximized.

8. The apparatus according to claim 1, wherein said detection means includes at least two X-axis sensors each having photosensitive portions linearly arrayed in an X-axis direction and at least two Y-axis sensors each having photosensitive portions linearly arrayed in a Y-axis direction, the sensors in the respective axial directions having detection regions on the input screen which partially overlap each other.

9. The apparatus according to claim 8, wherein said calculation means determines an origin on the coordinate input screen on the basis of the output information from said detection means.

10. The apparatus according to claim 8, wherein said calculation means determines a magnification used to calculate the coordinate values of the light formed on the coordinate input screen on the basis of the output information from said detection means.

11. The apparatus according to claim 8, wherein said calculation means determines a fixed input point on the coordinate input screen on the basis of the output information from said detection means.

12. The apparatus according to claim 1, further comprising output means for outputting to an external device coordinate information of a predetermined position on the coordinate input screen.

14. The method according to claim 13, wherein in the calculation step, first calculation for calculating the coordinate values of the light formed on the coordinate input screen using the output information at the first and second positions and second calculation for performing, for a result of the first calculation, correction calculation of the coordinate values of the light formed on the coordinate input screen using the output information at the third position can be executed.

15. The method according to claim 14, wherein when coordinate values as the result of the first calculation are (X′

,Y′

), and coordinate values as a result of the second calculation are (X,Y), X is a dependent function of X′ and

Y′

, and Y is a dependent function of X′ and

Y′

.

16. The method according to claim 14, further comprising the determination step of determining on the basis of the result of the first calculation whether the second calculation is to be executed.

17. The method according to claim 13, wherein the third position is at least one of four corners of a coordinate input effective area of the coordinate input screen.

18. The method according to claim 13, wherein

a detection section for executing detection in the detection step comprises an X-axis sensor in which photosensitive portions are linearly arrayed in an X-axis direction and a Y-axis sensor in which photosensitive portions are linearly arrayed in a Y-axis direction,

an image of the light is formed on the X-axis sensor through a cylindrical lens having an axis in the Y-axis direction, and

the image of the light is formed on the Y-axis sensor through a cylindrical lens having an axis in the X-axis direction.

19. The method according to claim 18, wherein the third position is set at a position in the coordinate input effective area, where an angle made by a light beam from an incident position on the cylindrical lens and a perpendicular to the photosensitive portions of the detection step is maximized.

20. The method according to claim 13, wherein a detection section for executing detection in the detection step includes at least two X-axis sensors each having photosensitive portions linearly arrayed in an X-axis direction and at least two Y-axis sensors each having photosensitive portions linearly arrayed in a Y-axis direction, the sensors in the respective axial directions having detection regions on the input screen which partially overlap each other.

21. The method according to claim 20, wherein in the calculation step, an origin on the coordinate input screen is determined on the basis of the output information from the detection step.

22. The method according to claim 20, wherein in the calculation step, a magnification used to calculate the coordinate values of the light formed on the coordinate input screen is determined on the basis of the output information from the detection step.

23. The method according to claim 20, wherein in the calculation step, a fixed input point on the coordinate input screen is determined on the basis of the output information from the detection step.

24. The method according to claim 13, further comprising the output step of outputting to an external device coordinate information of a predetermined position on the coordinate input screen.

13. A control method for a coordinate input apparatus for irradiating a coordinate input screen with light from a pointing device, and generating coordinates corresponding to the light, comprising:

the detection step of detecting the light irradiated on the coordinate input screen from the pointing device; and

the calculation step of calculating coordinate values of the light irradiated on the coordinate input screen using at least two of pieces of output information by light at least at three known positions including first to third positions in the detection step.

25. A program for causing a computer to control a coordinate input apparatus for irradiating a coordinate input screen with light from a pointing device, and generating coordinates corresponding to the light, comprising:

a program code of the detection step of detecting the light irradiated on the coordinate input screen from the pointing device; and

a program code of the calculation step of calculating coordinate values of the light irradiated on the coordinate input screen using at least two of pieces of output information by light at least at three known positions including first to third positions in the detection step.