Position detecting device

• US 20080150915A1
• Filed: 08/08/2007
• Published: 06/26/2008
• Est. Priority Date: 12/21/2006
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Asamura, Yoshinori, Shibue, Shigenori
• Granted Patent: US 8,094,138 B2
• Time in Patent Office: Days
• US Class Current: 345/176
• CPC Class Codes: G06F 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• 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 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

An object is to provide a position detecting device that is able to accurately detect an indicated position via an indicating unit or device even when a water droplet or the like is formed upon the position-detecting-device'"'"'s surface.

The position detecting device comprises: a light-guide plate 1 for placement upon a displaying surface of a displaying device, and made of a translucent material; an emitting unit 2 for emitting, from the sides of the light-guide plate 1, arranged in line along the X-axis and the Y-axis, a plurality of light beams each of a predetermined width, so as to be totally reflected thickness-wise within the light-guide plate 1 and to travel heading in predetermined directions parallel to the plane of the light-guide plate 1; an emission-control unit 3 for controlling the emitting unit 2 so as to make the light beams each scan the light-guide plate 1 in progression along the sides thereof, in an X-axis direction and in a Y-axis direction; at least one indicating device 4 having a light-guiding part 41 for guiding, by contacting the light-guide plate 1, thereinto light traveling within the light-guide plate 1, and a detection unit 42 for outputting, by detecting the light guided via the light-guiding part 41, a detection signal; and a coordinate calculating unit 43 for calculating, based on a scanned position derived from the detection signal and the emission-control unit 3, a coordinate position where the at least one indicating device 4 contacts the light-guide plate 1.

Claims

1. A position detecting device, comprising:

a light-guide plate for placement upon a displaying surface of a displaying device, and made of a translucent material;

an emitting unit for emitting, from sides of said light-guide plate, arranged in line along the X-axis and the Y-axis, a plurality of light beams each of a predetermined width, so as to be totally reflected thickness-wise within said light-guide plate and to travel heading in predetermined directions parallel to the light-guide-plate plane;

an emission-control unit for controlling said emitting unit so as to make the light beams each scan said light-guide plate in progression along the sides thereof, in an X-axis direction and in a Y-axis direction;

at least one indicating device having

a light-guiding part for guiding, by contacting said light-guide plate, thereinto light traveling within said light-guide plate, and

a detection unit for outputting, by detecting the light guided via the light-guiding part, a detection signal; and

a coordinate calculating unit for calculating, based on a scanned position derived from the detection signal and said emission-control unit, a coordinate position where said at least one indicating device contacts said light-guide plate.

2. The position detecting device as set forth in claim 1, wherein

the emitting unit has a plurality of light sources that outputs the light beams along the sides of the light-guide plate.

3. The position detecting device as set forth in claim 1, wherein

the emitting unit has a plurality of shutters that controls emission of the light beams along the sides of the light-guide plate.

4. The position detecting device as set forth in any one of claims 1 through 3, wherein

said at least one indicating device has said coordinate calculating unit, and a transmitting unit for transmitting externally, as a coordinate signal, the coordinate position calculated by said coordinate calculating unit.

5. The position detecting device as set forth in claim 4, wherein

said at least one indicating device includes a plurality of indicating devices each having different identification information, and transmitting, together with the coordinate signal, an identification signal based on its identification information;

the position detecting device further comprising

a coordinate outputting device for receiving the identification signal and the coordinate signal transmitted from said at least one indicating device, and for outputting, based on the received identification and coordinate signals, the coordinate position, so as to distinguish the plurality of indicating devices from each other.

6. The position detecting device as set forth in claim 1, wherein

the emitting unit takes, before and after the light beams'"'"' scanning in progression, a first simultaneous control and a second simultaneous control whereby the light beams are emitted at the same time.

7. The position detecting device as set forth in claim 1, wherein

the light-guide plate is constructed of a first light-guide plate, and a second light-guide plate that is softer than the first light-guide plate and overlaid thereupon.