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Large scale movie display system with multiple gray levels

  • US 5,198,803 A
  • Filed: 06/06/1990
  • Issued: 03/30/1993
  • Est. Priority Date: 06/06/1990
  • Status: Expired due to Fees
First Claim
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1. A large scale electronic display board system for displaying images in response to an image signal, said system comprising:

  • light emitting diode (LED) display for displaying images in multiple gray levels, said LED display being an N by M array of LEDs, where N and M are integers greater than or equal to 2, having a common ground and a common voltage source; and

    a current image circuit corresponding to each LED in said LED display for linearly controlling a gray level of said LED, each current image circuit comprising;

    a MOSFET large channel width transistor connected to said LED for lighting said LED in accordance with said image signal,a MOSFET control transistor connected to said large channel width transistor for supplying said image signal to said large channel width transistor in response to a control signal,a holding capacitor connected between a drain of said control transistor and said common ground for refreshing said image signal supplied to said large channel width transistor,a MOSFET small channel width transistor connected to said control transistor for supplying said image signal to said control transistor, said large channel width transistor having a channel width which is a multiple of a channel width of said small channel width transistor.

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