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Control circuit for an LED traffic light using a pulse width modulation signal

  • US 7,994,937 B2
  • Filed: 07/07/2008
  • Issued: 08/09/2011
  • Est. Priority Date: 04/28/2008
  • Status: Expired due to Fees
First Claim
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1. A control circuit for traffic light comprising:

  • a pulse control circuit, comprising a control chip capable of outputting a low level signal and a pulse-width modulation (PWM) signal by turns, wherein the duration of the low level signal is longer than that of the PWM signal;

    a control switch element;

    a control drive circuit for receiving the signals output from the control chip and controlling the control switch element, wherein the control drive circuit comprises a drive switch element, the drive switch element comprises;

    a first drive switch terminal connected to the control chip;

    a second drive switch terminal connected to the control switch element and also connected to a voltage source through a first drive circuit resistor; and

    a third drive switch terminal that is grounded;

    a power source; and

    an LED connecting to the power source via the control switch element;

    wherein the switch element is configured to control the power source to supply power to the LED when the signals output from the control chip are high, and not to supply power to the LED when the signals output from the control chip are low.

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