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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
First Claim
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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.

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