DRIVING CIRCUIT FOR A LIGHT EMITTING COMPONENT AND CONTROL CIRCUIT THEREOF

• US 20160050727A1
• Filed: 04/17/2015
• Published: 02/18/2016
• Est. Priority Date: 08/13/2014
• Status: Active Grant

• Current Assignee: Leh Chu Enterprise Company Limited
• Original Assignee: Wen-Chin Shiau
• Inventors: SHIAU, Wen-Chin
• Granted Patent: US 9,839,078 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G05F 1/00 Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
• CPC Class Codes: H05B 45/38 using boost topology
• CPC Class Codes: H05B 47/20 Responsive to malfunctions or to light source life; for protection

Abstract

A driving circuit includes a control circuit and a boost converter circuit. The control circuit receives a sense voltage associated with a direct-current (DC) source voltage, and generates a control signal with a duty cycle that varies with the sense voltage in a monotonically increasing manner. The boost converter circuit receives the DC source voltage and the control signal, thereby providing a driving current for driving light emission of a light emitting component. The driving current has a magnitude positively correlated to the duty cycle of the control signal.

Claims

1. A driving circuit for driving light emission of a light emitting component, comprising:

a control circuit disposed to receive a sense voltage associated with a direct-current (DC) source voltage, and configured to generate a control signal having a duty cycle that varies with the sense voltage in a monotonically increasing manner; and

a boost converter circuit disposed to receive the DC source voltage and the control signal, and configured to provide a driving current for driving light emission of the light emitting component, the driving current having a magnitude positively correlated to the duty cycle of the control signal.

2. The driving circuit according to claim 1, wherein said boost converter includes:

a diode having an anode, and a cathode at which the driving current is outputted;

an inductor having a first terminal disposed to receive the DC source voltage, and a second terminal coupled to said anode of said diode; and

a control switch configured to make or break electrical connection between a ground node and a common node of said diode and said inductor according to the control signal.

3. The driving circuit according to claim 2, further comprising a current switch disposed to receive a switch signal, and configured to make or break electrical connection between said cathode of said diode and an anode of the light emitting component according to the switch signal, thereby controlling flow of the driving current from said boost converter circuit to the light emitting component.

4. The driving circuit according to claim 3, wherein said control circuit is further disposed to receive a select signal, and is further configured to generate the switch signal according to the select signal.

5. The driving circuit according to claim 1, wherein said control circuit includes:

a reference circuit disposed to receive the sense voltage, and configured to generate a reference voltage having a first preset voltage magnitude when the sense voltage is lower than the first preset voltage magnitude, and having a second preset voltage magnitude higher than the first preset voltage magnitude when the sense voltage is higher than the second preset voltage magnitude;

an oscillator circuit configured to generate an oscillating signal having a predetermined frequency and a triangular waveform; and

a pulse width modulation circuit configured to receive the reference voltage from said reference circuit and the oscillating signal from said oscillator circuit, to thereby generate the control signal by pulse width modulation, the control signal having a frequency associated with the oscillating signal, the duty cycle of the control signal being associated with the oscillating signal and the reference voltage.

6. The driving circuit according to claim 5, wherein said reference circuit, said oscillator circuit and said pulse width modulation circuit are cooperatively configured such that the control signal satisfies:

7. The driving circuit according to claim 1, further comprising two series-connected resistors that have a first terminal disposed to receive the DC source voltage, a second terminal disposed to receive a reference voltage, and a common node coupled to said control circuit for providing the sense voltage thereto.

8. A control circuit for generating a control signal to a boost converter circuit to control light emission of a light emitting component, the boost converter circuit being configured to provide to the light emitting component a driving current with a magnitude associated with a duty cycle of the control signal, said control circuit comprising:

a reference circuit disposed to receive a sense voltage, and configured to generate a reference voltage having a first preset voltage magnitude when the sense voltage is lower than the first preset voltage magnitude, and having a second preset voltage magnitude higher than the first preset voltage magnitude when the sense voltage is higher than the second preset voltage magnitude;

an oscillator circuit configured to generate an oscillating signal having a predetermined frequency and a triangular waveform; and

a pulse width modulation circuit configured to receive the reference voltage from said reference circuit and the oscillating signal from said oscillator circuit, to thereby generate the control signal by pulse width modulation, the control signal having a frequency associated with the oscillating signal, the duty cycle of the control signal being associated with the oscillating signal and the reference voltage, and varying with the sense voltage in a monotonically increasing manner.

9. The control circuit according to claim 8, wherein said reference circuit, said oscillator circuit and said pulse width modulation circuit are cooperatively configured such that the control signal satisfies: