Lighting control circuit

Abstract

A lighting control circuit includes a functional control circuit, a light source driving circuit, and a constant current circuit. The functional control circuit has a first functional contact and a second functional contact. The light source driving circuit is electrically connected to the functional control circuit and includes a plurality of light-emitting diodes (LEDs), a first Zener diode, a second Zener diode, a first transistor, and a transistor. The transistor is electrically connected to the first transistor, the first Zener diode, and the second Zener diode, and the first transistor is connected across one of the LEDs. The constant current circuit is electrically connected to the light source driving circuit and the first functional contact and includes a second transistor, a third transistor, a first resistor, a second resistor, and a third resistor. When the first functional contact receives a voltage within a specified range, one of the LEDs is short-circuited and does not light up, while the others light up, and the first, second, and third resistors limit the current.

Claims

1. A lighting control circuit, comprising: A functional control circuit has a first functional contact and a second functional contact; a light source driving circuit electrically connected to the functional control circuit, and includes a plurality of light-emitting diodes, a first Zener diode, a second Zener diode, a first transistor, and a transistor, wherein the transistor is electrically connected to the first transistor, the first Zener diode, and the second Zener diode, and the first transistor is connected across one of the light-emitting diodes; and a constant current circuit electrically connected to the light source driving circuit and the first functional contact, and includes a second transistor, a third transistor, a first resistor, a second resistor, and a third resistor, wherein when a voltage within a voltage range is input to the first functional contact, satisfying the voltage of the first Zener diode, the first transistor conducts, one of the light-emitting diodes is short-circuited and does not light up, the remaining light-emitting diodes light up, the second transistor conducts, the third transistor conducts, and the first resistor, the second resistor, and the third resistor limit the current.

2. The lighting control circuit as described in claim 1, further comprising: A failure function circuit is electrically connected to the light source driving circuit and the constant current circuit, and includes a power transistor and a fourth transistor, wherein when one of the light-emitting diodes is disconnected, the fourth transistor is turned on and the power transistor is not turned on, so that the light-emitting diodes are not lit.

3. The lighting control circuit as described in claim 1, wherein when the voltage input to the first functional contact is greater than the upper limit of the voltage range, the voltage of the first Zener diode and the voltage of the second Zener diode are satisfied, the transistor is turned on, the first transistor is not turned on, causing the light-emitting diodes to light up, and the second transistor is not turned on, the third transistor is turned on, and the first resistor and the third resistor limit the current.

4. The lighting control circuit as described in claim 1, wherein when the second functional contact is input with a voltage within the voltage range, the voltage of the first Zener diode is satisfied, the first transistor is turned on, one of the light-emitting diodes is short-circuited and does not light up, the other light-emitting diodes are lit up, the second transistor is turned on while the third transistor is not turned on, and the first resistor and the second resistor limit the current.

5. The lighting control circuit as described in claim 1, wherein when the voltage input to the second functional contact is greater than the upper limit of the voltage range, the voltage of the first Zener diode and the voltage of the second Zener diode are satisfied, the transistor is turned on, the first transistor is not turned on, causing the light-emitting diodes to light up, the second transistor is not turned on, the third transistor is not turned on, and the first resistor limits the current.

6. The lighting control circuit as described in claim 1, wherein when both the first functional contact and the second functional contact are input with voltages within the voltage range, the voltage of the first Zener diode is satisfied, the first transistor is turned on, one of the light-emitting diodes is short-circuited and does not light up, the remaining light-emitting diodes are lit up, the second transistor is turned on, the third transistor is turned on, and the first resistor, the second resistor, and the third resistor limit the current.

7. The lighting control circuit as described in claim 1, wherein when the voltage input to the first functional contact and the voltage input to the second functional contact are both greater than the upper limit of the voltage range, the voltage of the first Zener diode and the voltage of the second Zener diode are satisfied, the transistor is turned on, the first transistor is not turned on, causing the light-emitting diodes to light up, the second transistor is not turned on, the third transistor is turned on, and the first resistor and the third resistor limit the current.

8. The lighting control circuit as described in claim 1, wherein when the voltage input to the first functional contact is greater than the lower limit of the voltage range, the voltage of the first Zener diode is satisfied, the first transistor is turned on, one of the light-emitting diodes is short-circuited and does not light up, the other light-emitting diodes are lit up, the second transistor is turned on, and the third transistor is turned on.

9. The lighting control circuit as described in claim 1, wherein when the voltage input to the first functional contact is greater than the upper limit of the voltage range, the voltage of the second Zener diode is satisfied, the transistor is turned on, the first transistor is not turned on, the second transistor is not turned on, the light-emitting diodes are lit, and the third transistor is turned on.

10. The lighting control circuit as claimed in claim 1, wherein when the voltage input to the second functional contact is greater than the lower limit of the voltage range, the voltage of the first Zener diode is satisfied, the first transistor is turned on, one of the light-emitting diodes is short-circuited and not lit, the other light-emitting diodes are lit, the second transistor is turned on, and the third transistor is not turned on.

11. The lighting control circuit as claimed in claim 1, wherein when the voltage input to the second functional contact is greater than the upper limit of the voltage range, the voltage of the second Zener diode is satisfied, the transistor is turned on, the first transistor is not turned on, the second transistor is not turned on, the light-emitting diodes are lit, and the third transistor is not turned on.

12. The lighting control circuit as claimed in claim 1, wherein the light-emitting diodes include at least four series-connected plurality of red light-emitting diodes, and the constant current circuit is configured to maintain a constant current through the red light-emitting diodes in a voltage range of 8V to 16V and to ensure that the brightness of the red light-emitting diodes is uniform.

13. The lighting control circuit as claimed in claim 1, wherein the light-emitting diodes include at least three series-connected plurality of red light-emitting diodes, and the constant current circuit is configured to maintain a constant current through the red light-emitting diodes in a voltage range of 8V to 16V and to ensure that the brightness of the red light-emitting diodes is uniform.

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