POWER SUPPLY DEVICE AND LIGHTING EQUIPMENT

• US 20110057576A1
• Filed: 09/01/2010
• Published: 03/10/2011
• Est. Priority Date: 03/24/2008
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Lighting & Technology Corporation (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Lighting & Technology Corporation (Toshiba Corporation)
• Inventors: Shimizu, Keiichi, Hiramatsu, Takuro, OTAKE, Hirokazu, Nishiie, Mitsuhiko
• Granted Patent: US 8,354,804 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H02M 1/0025 Arrangements for modifying reference values, feedback values or error values in the control loop of a converter
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/34 Voltage stabilisation; Maintaining constant voltage
• CPC Class Codes: H05B 45/345 Current stabilisation; Maintaining constant current
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/385 using flyback topology
• CPC Class Codes: H05B 47/10 Controlling the light source
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

In a power supply device according to one embodiment, a reference signal Vref1, which changes from a value corresponding to a maximum current in a full lighting state to that corresponding to a minimum current in case of a deepest dimming depth, and a reference signal Vref2, which changes from a value corresponding to a load voltage at the time of a maximum current in a full lighting state to that corresponding to a minimum current in case of the deepest dimming depth, are prepared in accordance with dimming depths of a dimming signal. In a shallow dimming depth region close to a full lighting state, the reference signal Vref1 is selected to apply constant-current control to light-emitting diodes in a current control mode. In a deep dimming depth region, the reference signal Vref2 is selected to apply constant-voltage control to the diodes in a voltage control mode.

Claims

1. A power supply device comprising:

a semiconductor light-emitting element;

a current control circuit which controls a current supplied to the semiconductor light-emitting element;

a voltage control circuit which controls a voltage applied to the semiconductor light-emitting element; and

a dimming controller which receives a dimming signal having a certain dimming depth, sets a current control mode and/or a voltage control mode according to the dimming depth, controls the current control circuit to drive the semiconductor light-emitting element at a target current specified depending on the dimming depth when the current control mode is set, and controls the voltage control circuit to drive the semiconductor light-emitting element at a target voltage specified depending on the dimming depth when the voltage control mode is set.

2. The power supply device according to claim 1, wherein the dimming controller includes a reference signal generator which generates a first reference signal and a second reference signal that are specified according to the dimming depth and respectively depend on the target current and the target voltage, and a comparator which compares the current supplied to the semiconductor light-emitting element with the first reference signal, compares the voltage applied to the semiconductor light-emitting element with the second reference signal, and sets the current control mode and/or the voltage control mode.

3. The power supply device according to claim 1, wherein the dimming controller sets a power control mode between the current control mode and the voltage control mode according to the dimming depth, controls the current control circuit to drive the semiconductor light-emitting element at the target current specified depending on the dimming depth, and controls the voltage control circuit to drive the semiconductor light-emitting element at the target voltage specified depending on the dimming depth in the power control mode.

6. A lighting equipment comprising:

a power supply device according to claim 1; and

an equipment main body having the power supply device.

4. A power supply device comprising:

a semiconductor light-emitting element;

a voltage detection circuit which detects a voltage applied to the semiconductor light-emitting element, and outputs a first detection signal;

a current detection circuit which detects a current supplied to the semiconductor light-emitting element, and outputs a second detection signal; and

a dimming controller which receives a dimming signal which is set at one of a deepest first dimming depth, a shallowest second dimming depth, and a certain third dimming depth between the first dimming depth and the second dimming depth, drive-controls the semiconductor light-emitting element according to the first detection signal so that the voltage becomes a first target value when the first dimming depth is set, drive-controls the semiconductor light-emitting element according to the second detection signal so that the current becomes a second target value when the second dimming depth is set, and drive-controls the semiconductor light-emitting element according to the first detection signal and the second detection signal so that the voltage and the current respectively become a third target value and a fourth target value when the third dimming depth is set, wherein the dimming controller drive-controls the semiconductor light-emitting element depending on the first detection signal compared to the second detection signal as the third dimming depth is closer to the first dimming depth, and drive-controls the semiconductor light-emitting element depending on the second detection signal compared to the first detection signal as the third dimming depth is closer to the second dimming depth.

5. The power supply device according to claim 4, wherein the dimming controller includes a multiplier which outputs a product signal obtained by multiplying the first detection signal by a coefficient which increases depending on a magnitude of the third dimming depth, an adder which outputs a sum signal obtained by adding the product output to the second detection signal, and a driving controller which drive-controls the semiconductor light-emitting element according to the sum signal.

7. A lighting equipment comprising:

a power supply device according to claim 4; and

an equipment main body having the power supply device.