Coordinate input device, control method therefor, and control program for implementing the method

• US 20060007185A1
• Filed: 06/03/2005
• Published: 01/12/2006
• Est. Priority Date: 06/03/2004
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kobayashi, Kiwamu
• Granted Patent: US 7,525,536 B2
• Time in Patent Office: Days
• US Class Current: 345/176
• CPC Class Codes: G02B 5/124 plural reflecting elements forming part of a unitary plate or sheet
• CPC Class Codes: G06F 3/03542 Light pens for emitting or receiving light
• CPC Class Codes: G06F 3/0423 using sweeping light beams, e.g. using rotating or vibrating mirror
• CPC Class Codes: G06F 3/0428 by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421

Abstract

A coordinate input device which is capable of performing accurate and appropriate detection of a pen-up/pen-down state over the entire coordinate input surface, based on motion of an indication tool or the like in a direction substantially perpendicular to the coordinate input surface, and realizing a function equivalent to that of an indication tool equipped with a communication function without using the tool. A light-shaded position shaded from light on the coordinate input surface by input of the indication tool on the coordinate input surface is detected, and then the coordinates of the light-shaded position are calculated. Further, the pen-up/pen-down state of the indication tool is determined based on a temporal change in light shading in the light-shaded position.

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 detector section that detects light;

a coordinate calculating section that calculates coordinates of the position indicated by the indication means, based on a 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.

2. A coordinate input device as claimed in claim 1, comprising a light-projecting section that emits light in planar directions along the input surface, and a reflective section that reflects emitted light from said light-projecting section, and

wherein:

said detector section is configured to receive the reflected light from the reflective section, pixel by pixel, and detect the light intensity distribution of the reflected light, and

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.

3. A coordinate input device as claimed in claim 1, comprising a light-projecting section that emits light in planar directions along the input surface, and a reflective section that reflects emitted light from said light-projecting section, and

wherein:

said detector section is configured to receive the reflected light from the reflective section, pixel by pixel, and detect the light intensity distribution of the reflected light; and

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 second light-shading amount obtained by adding together changes caused by light shading, in a distribution waveform obtained by normalizing a light intensity distribution formed when a light-shaded portion shaded from light by the indication means exists on the input surface, by 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 second width as a pixel range within which the changes caused by light shading exceed a predetermined level.

4. A coordinate input device as claimed in claim 2, wherein only when a magnitude of the temporal change in the first light-shading amount is not larger than a predetermined threshold value, and at the same time the temporal change is within a time period defined between a time point the temporal change assumes a maximal value and a time point the temporal change assumes a first minimal value thereafter, said determining section determines the input state of the indication means as the pen-down state, whereas when the input state of the indication means is not determined as the pen-down state, said determining section determines the input state of the indication means as the pen-up state.

5. A coordinate input device as claimed in claim 2, wherein only when the first light-shading amount is larger than a predetermined threshold value, said determining section determines whether the input state of the indication means is the pen-up state or the pen-down state.

6. A coordinate input device as claimed in claim 3, wherein only when a magnitude of the temporal change in the second light-shading amount is not larger than a predetermined threshold value, and at the same time the temporal change is within a time period defined between a time point the temporal change assumes a maximal value and a time point the temporal change assumes a first minimal value thereafter, said determining section determines the input state of the indication means as the pen-down state, whereas when the input state of the indication means is not determined as the pen-down state, said determining section determines the input state of the indication means as the pen-up state.

7. A coordinate input device as claimed in claim 3, wherein only when the second light-shading amount is larger than a predetermined threshold value, said determining section determines whether the input state of the indication means is the pen-up state or the pen-down state.

8. A coordinate input device as claimed in claim 2, wherein only when a magnitude of the temporal change in the first width is not larger than a predetermined threshold value and at the same time the temporal change is within a time period defined between a time point the temporal change assumes a maximal value and a time point the temporal change assumes a first minimal value thereafter, said determining section determines the input state of the indication means as the pen-down state, whereas when the input state of the indication means is not determined as the pen-down state, said determining section determines the input state of the indication means as the pen-up state.

9. A coordinate input device as claimed in claim 3, wherein only when a magnitude of the temporal change in the second width is not larger than a predetermined threshold value, and at the same time the temporal change is within a time period defined between a time point the temporal change assumes a maximal value and a time point the temporal change assumes a first minimal value thereafter, said determining section determines the input state of the indication means as the pen-down state, whereas when the input state of the indication means is not determined as the pen-down state, said determining section determines the input state of the indication means as the pen-up state.

10. A coordinate input device as claimed in claim 1, wherein when the input state of the indication means continues to be determined as the pen-up state over a predetermined time period, said determining section determines the input state of the indication means as the pen-up state when the predetermined time period has elapsed.

11. A coordinate input device as claimed in claim 1, further comprising a display device disposed on the input surface.

12. A method of controlling a coordinate input device that detects a position on an input surface indicated by indication means and determines coordinates of the position, comprising:

a detection step of detecting light;

a coordinate calculating step of calculating coordinates of the position indicated by the indication means, based on a light intensity distribution detected in said detection step; and

a determining step of determining an input state of the indication means with respect to the input surface, based on a temporal change in the light intensity distribution.

13. A program for causing a computer to execute a control method for a coordinate input device that detects a position on an input surface indicated by indication means and determines coordinates of the position, comprising:

a detection module for detecting light;

a coordinate calculating module for calculating coordinates of the position of indicated by the indication means, based on a light intensity distribution detected by said detection module; and

a determination module for determining an input state of the indication means on the input surface, based on a temporal change in the light intensity distribution.