Coordinate input system and display apparatus

• US 6,339,748 B1
• Filed: 11/05/1998
• Issued: 01/15/2002
• Est. Priority Date: 11/11/1997
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Hiramatsu, Kazunori
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): VO, HIEN XUAN
• Application Number:
  US09/186,373
• Time in Patent Office: 1,167 Days
• Field of Search: 702/159, 345/173, 345/175, 345/156, 345/157, 345/158, 353/66, 353/70, 353/28, 353/34, 359/443, 359/453, 359/635, 359/636, 359/630
• US Class Current: 702/159
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• 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

The present invention has a object to provide a coordinate input system imparting a coordinate input function onto a transmissive screen for image display such as a rear projecting display apparatus, which permits use of a ray reflecting indicator smaller in size and lighter in weight than a light pen and to improve easiness to use.

The coordinate input system of the invention has an infrared ray source 3 which projects an infrared ray onto the back surface of the transmissive screen 2 for image display, a CCD camera 4 which covers the back surface of the transmissive screen as a senses range, and an image information processing circuit 5 which generates coordinate information of a ray reflecting indicator 1 located in front of the transmissive screen 2, from output image information of the CCD camera.

Claims

1. A coordinate input system, that provides a coordinate input function to a transmissive screen which forms an image projected by an image projector, comprising:

an invisible ray projector which projects invisible rays to a plane of said transmissive screen;

an invisible ray detector which detects reflected rays which are reflected ones of the invisible rays; and

a coordinate processor which determines coordinates relative to said transmissive screen based on an output signal generated by the invisible ray detector.

2. The coordinate input system according to claim 1, the invisible ray projector having a projection optical axis that is not normal to the plane of said transmissive screen.

3. The coordinate input system according to claim 1, the invisible ray detector having an optical axis that is not normal to the plane of said transmissive screen.

4. The coordinate input system according to claim 1, the invisible ray projector comprising a plurality of invisible ray sources which project the invisible rays to different areas of the plane of said transmissive screen.

5. The coordinate input system according to claim 4, the plurality of invisible ray sources having projection optical axes that are not normal to the plane of said transmissive screen, and angles of incidence of the projection optical axes of said plurality of invisible ray sources with the plane of said transmissive screen are different from each other.

6. The coordinate input system according to claim 1, further comprising a synchronizer which synchronizes a turn-on and a turn-off timing of the invisible rays projected by the invisible ray projector with a frame timing of the invisible ray detector.

7. The coordinate input system according to claim 1, further comprising a synchronizer which synchronizes a frame timing of the image projected by the image projector with a frame timing of the invisible ray detector.

8. The coordinate input system according to claim 1, the coordinate processor having a disturbance discriminator which compares a luminance level of a turn-off signal generated by the invisible ray detector when the invisible rays are turned off a determination level.

9. The coordinate input system according to claim 1, further comprising an indicator that reflects the invisible rays projected by the invisible ray projector to produce the reflected rays.

10. The coordinate input system according to claim 9, the indicator including one of an object having a metal-plated tip, a mirror tipped object, or a light reflecting object.

11. The coordinate input system according to claim 9, the indicator having a reflective member, the reflective member having a selectivity for infrared rays.

12. The coordinate input system according to claim 9, the indicator comprising:

an optical filter that selectively allows transmission of infrared rays; and

an optical reflective member.

13. The coordinate input system according to claim 9, the invisible ray detector having an optical filter which selectively allows transmission of a wavelength range of the reflected rays produced by the indicator.

14. The coordinate input system according to claim 13, the wavelength range being in an infrared range.

15. The coordinate input system according to claim 1, the output generated by the invisible ray detector being a turn-on signal when the invisible rays projected by the invisible ray projector is turned on, and the output generated by the invisible ray detector being a turn-off signal when the invisible rays projected by the invisible ray projector is turned off.

16. The coordinate input system according to claim 15, the coordinate processor includes a subtracter which generates a difference between the turn on signal and the turn off signal.

17. The coordinate input system according to claim 1, the invisible ray detector including a CCD camera.

18. The coordinate input system according to claim 1, the invisible ray projector and the invisible ray detector facing the same side of the plane of the transmissive screen.

19. A display apparatus provided with a transmissive screen which forms an image projected by an image projector, the apparatus comprising:

an infrared ray projector which projects infrared rays onto a back of said transmissive screen;

an indicating device, the indicating device reflecting the infrared rays from a front of the transmissive screen producing reflected rays;

an image sensor which senses from the back of the transmissive screen an image of the reflected rays; and

an image information processor which determines coordinates specified by the indicating device on said transmissive screen based on an output image signal provided by said image sensor.

20. The coordinate input system according to claim 19, the indicating device including one of an object having a metal-plated tip, a mirror tipped object, or a light reflecting object.

21. The coordinate input system according to claim 19, the image sensor including a CCD camera.