| US 7,525,536 B2 | ||
| Coordinate input device, control method therefor, and control program for implementing the method | ||
| Kiwamu Kobayashi, Yokohama (Japan) | ||
| Assigned to Canon Kabushiki Kaisha, (Japan) | ||
| Filed on Jun. 03, 2005, as Appl. No. 11/145,118. | ||
| Claims priority of application No. 2004-166340 (JP), filed on Jun. 03, 2004. | ||
| Prior Publication US 2006/0007185 A1, Jan. 12, 2006 | ||
| Int. Cl. G06F 3/041 (2006.01) | ||
| U.S. Cl. 345—173 [345/175; 345/176; 178/18.01; 178/18.09] | 14 Claims |
| 1. A coordinate input device that detects a position on an input surface indicated by indication means and determines coordinates
of the position, comprising:
a light-projecting section that emits light in planar directions along the input surface;
a reflective section that reflects emitted light from said light-projecting section;
a detector section that receives the reflected light from the reflective section, pixel by pixel, and detects the light intensity
distribution of the reflected light;
a coordinate calculating section that calculates coordinates of the position indicated by the indication means, based on the
light intensity distribution detected by said detector section; and
a determining section that determines an input state of the indication means with respect to the input surface, based on a
temporal change in the light intensity distribution,
wherein said determining section determines whether the input state of the indication means is a pen-up state or a pen-down
state, based on a temporal change in a first light-shading amount obtained by adding together differences between a light
intensity distribution formed when a light-shaded portion shaded from light by the indication means exists on the input surface
and a light intensity distribution formed when no light-shaded portion exists on the input surface, in a direction along a
sequence of pixels, or based on a temporal change in a first width as a pixel range within which the differences exceed a
predetermined level.
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