Lighting Power Source and Luminaire

• US 20130119878A1
• Filed: 09/10/2012
• Published: 05/16/2013
• Est. Priority Date: 11/10/2011
• Status: Active Grant

• Current Assignee: Toshiba Lighting & Technology Corporation (Toshiba Corporation)
• Original Assignee: Toshiba Lighting & Technology Corporation (Toshiba Corporation)
• Inventors: Kitamura, Noriyuki, Otake, Hirokazu, Takahashi, Yuji
• Granted Patent: US 8,884,536 B2
• Time in Patent Office: Days
• US Class Current: 315/200.R
• CPC Class Codes: H05B 45/3575 by means of dummy loads or bleeder circuits, e.g. for dimmers
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]

Abstract

A lighting power source according to an embodiment includes a rectification circuit, a smoothing capacitor, a waveform shaping circuit, and a DC-DC converter. The rectification circuit rectifies an AC voltage input thereto.

The waveform shaping circuit is connected between the rectification circuit and the smoothing capacitor, performs a switching operation to repeat an ON state and an OFF state when the voltage output from the rectification circuit is relatively high, continues to be in the ON state to allow the current to flow to the rectification circuit when the voltage output from the rectification circuit is relatively low. The DC-DC converter converts a voltage charged in the smoothing capacitor.

Claims

1. A lighting power source comprising:

a rectification circuit configured to rectify an input AC voltage;

a smoothing capacitor;

a waveform shaping circuit connected between the rectification circuit and the smoothing capacitor, configured to perform a switching operation to repeat an ON state and an OFF state when the voltage output from the rectification circuit is relatively high, and configured to continue to be in the ON state to allow the current to flow to the rectification circuit when the voltage output from the rectification circuit is relatively low; and

a DC-DC converter configured to convert a voltage charged in the smoothing capacitor.

2. The lighting power source according to claim 1, further comprising a dimmer configured to control a timing for conducting the AC voltage to dim light.

3. The lighting power source according to claim 1, wherein the waveform shaping circuit includes a normally-on type element.

4. The lighting power source according to claim 1, wherein the waveform shaping circuit includes a normally-off type element supplied with the voltage charged in the smoothing capacitor and biased to the ON sate.

5. The lighting power source according to claim 1, wherein the waveform shaping circuit includes:

a choke coil; and

a switching element configured to allow a current to flow through the rectification circuit via the choke coil.

6. The lighting power source according to claim 5, wherein the switching element is controlled to the ON state or the OFF state on the basis of a current flowing through the choke coil.

7. The lighting power source according to claim 5, wherein the waveform shaping circuit further includes a drive winding magnetically coupled to the choke coil, and

a voltage induced in the drive winding is supplied to a control terminal of the switching element.

8. The lighting power source according to claim 5, wherein the waveform shaping circuit further includes a diode configured to allow a current to flow therethrough via the choke coil when the switching element is in the OFF sate.

9. The lighting power source according to claim 1, wherein the waveform shaping circuit is of a self exciting type and is configured to continue the switching operation or the ON state.

10. The lighting power source according to claim 2, wherein the value of the current flowed to the rectification circuit by the waveform shaping circuit continuously in the ON state is larger than the value of a holding current of the dimmer.

11. A luminaire comprising:

a lighting load; and

a lighting power source configured to supply power to the lighting load and including;

a rectification circuit configured to rectify an input AC voltage;

a smoothing capacitor;

a waveform shaping circuit connected between the rectification circuit and the smoothing capacitor, configured to perform a switching operation to repeat an ON state and an OFF state when the voltage output from the rectification circuit is relatively high, and configured to continue to be in the ON state to allow the current to flow to the rectification circuit when the voltage output from the rectification circuit is relatively low; and

a DC-DC converter configured to convert a voltage charged in the smoothing capacitor.

12. The luminaire according to claim 11, further comprising a dimmer configured to control a timing for conducting the AC voltage to dim light.

13. The luminaire according to claim 11, wherein the waveform shaping circuit includes a normally-on type element.

14. The luminaire according to claim 11, wherein the waveform shaping circuit includes a normally-off type element supplied with the voltage charged in the smoothing capacitor and biased to the ON sate.

15. The luminaire according to claim 11, wherein the waveform shaping circuit includes:

a choke coil; and

a switching element configured to allow a current to flow through the rectification circuit via the choke coil.

16. The luminaire according to claim 15, wherein the switching element is controlled to the ON state or the OFF state on the basis of a current flowing through the choke coil.

17. The luminaire according to claim 15, wherein the waveform shaping circuit further includes a drive winding magnetically coupled to the choke coil, and

a voltage induced in the drive winding is supplied to a control terminal of the switching element.

18. The luminaire according to claim 15, wherein the waveform shaping circuit further includes a diode configured to allow a current to flow therethrough via the choke coil when the switching element is in the OFF sate.

19. The luminaire according to claim 11, wherein the waveform shaping circuit is of a self exciting type and is configured to continue the switching operation or the ON state.

20. The luminaire according to claim 12, wherein the value of the current flowed to the rectification circuit by the waveform shaping circuit continuously in the ON state is larger than the value of a holding current of the dimmer.