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Matrix display device with light sensing function and time-shared amplifier

  • US 5,386,543 A
  • Filed: 07/21/1993
  • Issued: 01/31/1995
  • Est. Priority Date: 09/07/1992
  • Status: Expired due to Fees
First Claim
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1. A combined matrix display and light sensing device comprising:

  • (a) an array of display elements,(b) an array of light sensing elements which are responsive to illumination so as to provide an electrical charge indicative thereof,(c) first and second sets of address conductors connected with the arrays of display elements and light sensing elements, the display elements and the light sensing elements each being connected with an address conductor of each set,(d) a first drive circuit connected to the first set of address conductors for scanning the arrays,(e) a second drive circuit for providing data signals which are supplied to the display elements via address conductors of the second set,(f) a detection circuit for sensing the charge provided by the sensing elements, and comprising charge sensitive amplifier circuits, each having(1) an output,(2) a first input connected to an address conductor of the second set,(3) a second input for receiving a read potential, and(4) a capacitor and switch connected in parallel between the output and the first input, and(g) control means for opening and closing the switch of each charge sensitive amplifier circuit periodically and providing the read potential to the second input,characterised in that the control means is operable to apply to the second input of each charge sensitive amplifier circuit data signals from the second drive circuit when the switch is closed and said read potential when the switch is open.

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