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Electronic display having segments wherein each segment is capable of selectively illuminating two colors

  • US 4,488,149 A
  • Filed: 02/26/1981
  • Issued: 12/11/1984
  • Est. Priority Date: 02/26/1981
  • Status: Expired due to Fees
First Claim
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1. An electronic display, comprising:

  • a segment, comprising;

    a first light emitting diode having a cathode and an anode and emitting a first color when biased in the forward direction;

    a second lignt emitting diode having a cathode and an anode and emitting a second color when biased in the forward direction, the cathode of the first light emitting diode being connected to the anode of the second light emitting diode and the anode of the first light emitting diode being connected to the cathode of the second light emitting diode;

    means connected to the segment for selectively biasing one of the first and the second light emitting diodes in the forward direction, said means being connected to the common connection between the anode of the first light emitting diode and the cathode of the second light emitting diode and being connected to the common connection between the cathode of the first light emitting diode and the anode of the second light emitting diode, and said means selectively applying a bias to the common connection between the anode of the first light emitting diode and the cathode of the second light emitting diode and applying a negative bias to the common connection between the cathode of the first light emitting diode and the anode of the seocnd light emitting diode to bias the first light emitting diode in the forward direction, and said means selectively applying a positive bias to the common connection between the cathode of the first light emitting diode and the anode of the second light emitting diode and applying a negative bias to the common connection between the anode of the first light emitting diode and the cathode of the seocnd light emitting diode to bias the second light emitting diode in the forward direction;

    a color control providing a color signal, the color control signal being connected to and applied at the common connection between the anode of the first light emitting diode and the cathode of the second light emitting diode; and

    an inverting buffer receiving the color control signal and providing an inverted output signal, the inverted output signal being connected to and applied at the common connection between the cathode of the first light emitting diode and the anode of the second light emitting diode, the first light emitting diode being forward biased in the high state of the color control signal and the second light emitting diode being forward biased in the low state of the color control signal; and

    wherein the means for selectively biasing one of the first and the second light emitting diodes is defined further to include;

    a tri-state non-inverting buffer receiving the color control signal and providing an output signal connected to and received at the common connection between the anode of the first light emitting diode and the cathode of the second light emitting diode, the tri-state non-inverting buffer having a control input and providing a high impedance output signal in response to receiving a signal at the color control input in the low state and providing an output signal having the same state as the received signal in response to receiving a signal at the control input in the high state; and

    wherein the means for selectively biasing the first and the second light emitting diodes is defined further as applying the signal to the control input of the tri-state non-inverting buffer.

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