Signal apparatus, light emitting diode (LED) drive circuit, LED display circuit, and display system including the same

A light emitting diode circuit comprising:

• a first terminal;
• a second terminal;
• a forward circuit comprising:
• a number of light emitting diodes electrically connected in series, and
• a forward steering diode electrically connected in series with said light emitting diodes,
• wherein the series combination of said forward steering diode and said light emitting diodes is electrically connected between said first and second terminals, and
• wherein said series combination is structured to conduct current in a first direction with respect to said first and second terminals in order to illuminate said light emitting diodes;
• and
• a reverse circuit comprising:
• a resistor, and
• a reverse steering diode electrically connected in series with said resistor,
• wherein the series combination of said reverse steering diode and said resistor is electrically connected between said first and second terminals,
• wherein said series combination of said reverse steering diode and said resistor is structured to conduct current in a second direction with respect to said first and second terminals in order that said light emitting diodes are not illuminated, and
• wherein said second direction is opposite said first direction.

A light emitting diode drive circuit for driving a number of light emitting diode circuits, each of said light emitting diode circuits including a forward circuit having a number of light emitting diodes electrically connected in series, said light emitting diodes being structured to conduct current in a forward direction and to be responsively illuminated, each of said light emitting diode circuits also including a reverse circuit electrically connected in parallel with said forward circuit, said reverse circuit being structured to conduct current in a reverse direction which is opposite said forward direction, said light emitting diode drive circuit comprising:

• a processor circuit comprising:
• a number of first outputs,
• a number of second outputs,
• a first analog input,
• a second analog input, and
• a processor outputting said first and second outputs and inputting said first and second analog inputs;
• and
• for each of said number of light emitting diode circuits:
• a third input structured to receive a constant current,
• a third output including a voltage, said third output being structured to drive a corresponding one of said light emitting diode circuits,
• a first switch responsive to a corresponding one of the first outputs of said processor circuit, said first switch being closed to conduct said constant current in said forward direction to said third output, in order that said conducted constant current in said forward direction to said third output illuminates the light emitting diodes of the corresponding one of said light emitting diode circuits,
• a circuit structured to sink said current in said reverse direction,
• a second switch responsive to a corresponding one of the second outputs of said processor circuit, said second switch being closed to conduct said current in said reverse direction from said third output to said circuit structured to sink said current in said reverse direction, in order that said conducted current in said reverse direction from said third output flows in the reverse direction though the reverse circuit of the corresponding one of said light emitting diode circuits,
• a current sensor structured to sense said constant current in said forward direction to said third output or said current in said reverse direction from said third output and to output a sensed current signal to the first analog input of said processor circuit, and
• a voltage sensor structured to sense the voltage of said third output and to output a sensed voltage signal to the second analog input of said processor circuit.

A display system comprising:

• a constant current regulator including an output and a common terminal;
• a light emitting diode circuit comprising:
• a first terminal;
• a second terminal electrically connected to the common terminal of said constant current regulator;
• a forward circuit comprising:
• a number of light emitting diodes electrically connected in series, and
• a forward steering diode electrically connected in series with said light emitting diodes,
• wherein the series combination of said forward steering diode and said light emitting diodes is electrically connected between said first and second terminals, and
• wherein said series combination is structured to conduct current in a first direction with respect to said first and second terminals in order to illuminate said light emitting diodes;
• and
• a reverse circuit comprising:
• a resistor, and
• a reverse steering diode electrically connected in series with said resistor,
• wherein the series combination of said reverse steering diode and said resistor is electrically connected between said first and second terminals,
• wherein said series combination of said reverse steering diode and said resistor is structured to conduct current in a second direction with respect to said first and second terminals in order that said light emitting diodes are not illuminated, and
• wherein said second direction is opposite said first direction;
• and
• a light emitting diode drive circuit comprising:
• a processor circuit comprising:
• a first output,
• a second output,
• a first analog input,
• a second analog input, and
• a processor outputting said first and second outputs and inputting said first and second analog inputs;
• a third input structured to receive a constant current from the output of said constant current regulator,
• a third output including a voltage, said third output driving the first terminal of said light emitting diode circuit,
• a first switch responsive to the first output of said processor circuit, said first switch being closed to conduct said constant current in said forward direction to said third output, in order that said conducted constant current in said forward direction to said third output illuminates the light emitting diodes of said light emitting diode circuit,
• a sink circuit structured to sink said current in said reverse direction,
• a second switch responsive to the second output of said processor circuit, said second switch being closed to conduct said current in said reverse direction from said third output to said sink circuit structured to sink said current in said reverse direction, in order that said conducted current in said reverse direction from said third output flows in the reverse direction though the reverse circuit of said light emitting diode circuit,
• a current sensor structured to sense said constant current in said forward direction to said third output or said current in said reverse direction from said third output and to output a sensed current signal to the first analog input of said processor circuit, and
• a voltage sensor structured to sense the voltage of said third output and to output a sensed voltage signal to the second analog input of said processor circuit.