Touch panel coordinate input device having light filter

• US 4,751,379 A
• Filed: 10/02/1986
• Issued: 06/14/1988
• Est. Priority Date: 10/04/1985
• Status: Expired due to Fees

• Current Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Sasaki, Hiroaki, Hasegawa, Kazuo, Ouchi, Junichi
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Ruoff, Jessie
• Application Number:
  US06/914,283
• Time in Patent Office: 621 Days
• Field of Search: 250/221, 250/222.1, 340/555, 340/556, 340/557, 340/706, 340/709
• US Class Current: 250/221
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

A photodetection type coordinate input device includes a frame having a substantially rectangular opening formed in the center, a light-emitting element array composed of a plurality of light-emitting elements disposed along each of the two sides of the opening of the frame, a light-receiving element array composed of a plurality of light-receiving elements disposed along each of the two sides which respectively oppose the first two sides, and a filter provided in a part or the whole area of the opening and adapted to transmit desired light alone. The opening of the frame is disposed in front of a display to form a plurality of optical paths by pairs of light-emitting and -receiving elements, respectively, in front of the display screen of the display, and a position at which optical paths are blocked is detected to specify a coordinate position on the display screen, thereby inputting the coordinate position. The coordinate input device is provided with a recess for blocking the propagation of light toward the light-receiving element side. The recess is disposed in a region within the filter section which is closer to at least the light-receiving element side than a position which is located on the downstream side in a direction in which the light emitted from the light-emitting elements travels and which position is at a mid point between the light-emitting and -receiving elements.

Claims

1. In a photodetection type coordinate input device having a rectangular frame around a touch panel area, a light-emitting element array composed of a plurality of light-emitting elements disposed in rows on two adjacent sides of the frame, a light-receiving element array composed of a plurality of light-receiving elements disposed in rows on two other adjacent sides of the frame each of which faces opposite a respective one of the first-mentioned two sides, wherein each light-emitting element of the ligh-emitting element array is directed toward an opposing light-receiving element of the light-receiving element array across the touch panel area and forms a photodetection element pair therewith, and a filter provided in the touch panel area for ensuring transmission of light from the light-emitting elements to the light-receiving elements along desired ligh detection paths therebetween, whereby the plurality of photodetection element pairs form a matrix of light detection paths in front of a display screen of the corrdiate input device so that a position of the touch panel area at which ligh detection paths are blocked is detected as a corrdinate input position of the display screen,

the improvement comprising:

a planar portion disposed in parallel between the touch panel area of the frame and a the display screen, said planar portion having a given thickness and an inner side facing toward the touch panel area and an outer side facing toward the display screen, said planar portion having a recess formed in said outer side thereof protruding into the thickness of said planar portion for blocking spurous light entering said planar portion from propagating through said planar portion to the light-receiving elements.

2. A coordinate input device according to claim 1, wherein said filter includes side portions comprising a visible light-removing filter disposed in front of said light-emitting and -receiving elements.

3. A coordinate input device according to claim 1, wherein said planar portion is an operation panel disposed in front of the display screen of said display and adapted to transmit only desired light among various kinds of light emitted from said display screen.

4. A coordinate input device according to claim 1, wherein said filter comprises a visible light-removing filter disposed in front of said light-emitting and -receiving elements, and said planar portion as an operation panal disposed in front of the display screen of said display and adapted to be able to transmit only desired light among various kinds of light emitted from said display screen.

5. A coordinate input device according to claim 1, wherein said planar portion forms a part of said filter, said filter includes side portions disposed in front of the arrays of light-emitting and ligh-receiving elements, and said planar portion of said filter further has a projection formed at a position midway between the light-emitting elements and the light-receiving elements of the photodetection element pairs for preventing spurious light emitted from the light-emitting elements from being reflected from said planar portion toward the light-receiving elements.

6. A coordinate input device according to claim 1, wherein said planar portion is an operation panel of said coordinate input device mounted to said frame, and said recess is disposed on sides of said frame proximate the light-receiving elements.