Coordinate input apparatus

• US 6,317,266 B1
• Filed: 07/06/2000
• Issued: 11/13/2001
• Est. Priority Date: 07/07/1999
• 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): Mack, Ricky
• Application Number:
  US09/611,963
• Time in Patent Office: 495 Days
• Field of Search: 359/619, 341/5, 345/157, 345/158
• US Class Current: 359/619
• CPC Class Codes: G02B 27/20 for imaging minute objects, e.g. light-pointer
• 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 3/0425 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 coordinate input apparatus has a region with optical characteristics for transmitting light from a pointing tool, thereby preventing reflection of external light in the visible light range from the input surface of a coordinate input screen.

Claims

1. A coordinate input apparatus for irradiating a predetermined position on a coordinate input screen with light from a pointing tool to generate a light spot and generating coordinates corresponding to the light spot, comprising:

projection means for projecting an image onto the coordinate input screen; and

prevention means, having a region with optical characteristics for transmitting light from the pointing tool, for preventing reflection of external light in a visible light range from an input surface of the coordinate input screen.

2. The apparatus according to claim 1, wherein

the coordinate input screen has a Fresnel plate formed from Fresnel lenses and a lenticular plate formed from lenticular lenses having a diffusion function in a horizontal direction, and

the region having the optical characteristics is formed outside an exit region of image projection light related to the lenticular plate.

3. The apparatus according to claim 1, wherein the region having the optical characteristics is formed by one of a coating and dye having a transmission characteristic only in an infrared light wavelength range.

4. The apparatus according to claim 1, wherein the region having the optical characteristics is formed by one of a filter and film having a transmission characteristic only in an infrared light wavelength range.

5. The apparatus according to claim 4, wherein the filter or film has a curved surface in a transmission direction of light from the pointing tool.

6. The apparatus according to claim 1, wherein a surface of the region having the optical characteristics is matted.

7. The apparatus according to claim 1, wherein the region having the optical characteristics is formed outside an exit region of image projection light related to a front plate arranged in front of the lenticular plate.

8. The apparatus according to claim 1, wherein the region having the optical characteristics is formed in an entire region of a front plate arranged in front of the lenticular plate.

9. The apparatus according to claim 1, wherein in the region having the optical characteristics, a transmittance for the light from the pointing tool increases from a central portion of the coordinate input screen to a peripheral portion.