POWER SUPPLY UNIT HAVING DIMMER FUNCTION AND LIGHTING UNIT

• US 20100060204A1
• Filed: 09/10/2009
• Published: 03/11/2010
• Est. Priority Date: 09/10/2008
• 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: Hiramatsu, Takuro, Terasaka, Hiroshi, Nishiie, Mitsuhiko, Ohtake, Hirokazu
• Granted Patent: US 8,513,902 B2
• Time in Patent Office: Days
• US Class Current: 315/307
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: H05B 45/38 using boost topology
• CPC Class Codes: H05B 45/385 using flyback topology

Abstract

In a power supply unit, if a dimmer rate is changed within a range of k1, k2, . . . k7 by a dimmer signal k of a dimmer signal generator, light-emitting diodes are controlled to be lighted by a constant current characteristic in an area where the dimmer rate is small according to a load characteristic corresponding to the dimmer rates k1, k2, . . . k7. As the dimmer rate becomes deeper, a tendency of a constant voltage characteristic is gradually strengthened from a constant current characteristic so that the light-emitting diodes are lighted at the deeper dimmer rate.

Claims

1. A power supply unit, comprising:

a semiconductor light emitting moudule;

a power supply part which lights the semiconductor light emitting moudule in accordance with one of load characteristics, wherein the load characteristics have inclination lines extending from a base point, whose inclinations are changed depending on dimmer rates, respectively;

a voltage detecting part which detects a load voltage applied to the semiconductor light emitting moudule to generate a voltage detection signal;

a current detecting part which detects an electric current supplied to the semiconductor light emitting moudule to generate a current detection signal; and

a control part which controls the power supply part depending on the voltage detection signal, the current detection signal, and a dimmer signal having one of the dimmer rates, to adjust a power supplied to the semiconductor light emitting moudule from the power supply part and the power is set depending on one of the inclination lines of the load characteristic which is set in accordance with the dimmer rate.

2. The power supply unit according to claim 1, wherein the inclination lines of the load characteristics are radially extended from the base point DIa (constant value) depending on the dimmer rates, and each of the load characteristics is substantially expressed by a function formula of {I+k (V)=Dia}, where I represents the electric current flowing in the semiconductor light emitting moudule, V represents the load voltage applied to the semiconductor light emitting moudule, and k represents one of the dimmer rates.

3. The power supply unit according to claim 1, wherein the control part controls the power supply part depending on a constant current characteristic, a constant voltage characteristic, and a combination of a constant current characteristic and a constant voltage characteristic, if the dimmer rate is smaller than a predetermined rate, the current detection signal is weighted and thus a tendency of a constant current characteristic is strengthened, and if the dimmer rate is not smaller than the predetermined rate, the voltage detection signal is weighted and thus a tendency of a constant voltage characteristic is strengthened.

4. The power supply unit according to claim 2, wherein the control part controls the power supply part depending on a constant current characteristic, a constant voltage characteristic, and a combination of a constant current characteristic and a constant voltage characteristic, if the dimmer rate is smaller than a predetermined rate, the current detection signal is weighted and thus a tendency of a constant current characteristic is strengthened, and if the dimmer rate is not smaller than the predetermined rate, the voltage detection signal is weighted and thus a tendency of a constant voltage characteristic is strengthened.

5. A lighting unit comprising:

the power supply unit according claim 1; and

a unit main body having the power supply unit.

6. A lighting unit comprising:

the power supply unit according claim 2; and

a unit main body having the power supply unit.

7. A lighting unit comprising:

the power supply unit according claim 3; and

a unit main body having the power supply unit.

8. A lighting unit comprising:

the power supply unit according claim 4; and

a unit main body having the power supply unit.