Lighting circuit and illumination device

• US 8,427,070 B2
• Filed: 08/20/2010
• Issued: 04/23/2013
• Est. Priority Date: 08/21/2009
• Status: Expired due to Fees

• 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: Matsuda, Mitsuhiro
• Primary Examiner(s): Chang, Daniel D
• Application Number:
  US12/860,528
• Publication Number:
  US 20110043121A1
• Time in Patent Office: 977 Days
• Field of Search: 315/291, 315/224, 315/226, 315/244, 315/312, 315/307, 315/308, 315/209.R
• US Class Current: 315/291
• CPC Class Codes: H05B 45/3575 by means of dummy loads or bleeder circuits, e.g. for dimmers
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: H05B 45/385 using flyback topology

Abstract

A lighting circuit according to embodiments includes: a self-hold element connected in series to an AC power source that generates power for lighting an illumination load, together with the illumination load, the self-hold element being configured to control supply of the power provided by the AC power source to the illumination load by the self-hold element being turned on/off; a noise prevention circuit connected in parallel to the self-hold element; and a damping circuit configured to connect a damping resistance to the noise prevention circuit parallely only for a predetermined period from turning-on of the self-hold element, thereby preventing the self-hold element from being repeatedly turned on/off during a period in which the self-hold element is on under normal conditions, due to a transient during power supply.

Claims

1. A lighting circuit comprising:

a self-hold element connected in series to an AC power source that generates power for lighting an illumination load, together with the illumination load, the self-hold element being configured to control supply of the power provided by the AC power source to the illumination load by the self-hold element being turned on/off;

a noise prevention circuit connected in parallel to the self-hold element;

a damping circuit configured to connect a damping resistance to the noise prevention circuit parallely only for a predetermined period from turning-on of the self-hold element.

2. The lighting circuit according to claim 1, further comprising:

a rectifier circuit to which a voltage from the AC power source is applied via the self-hold element; and

a constant current circuit connected in parallel to an output end of the rectifier circuit together with the damping circuit, the constant current circuit being configured to drive the illumination load.

3. The lighting circuit according to claim 2,

wherein the damping circuit comprises:

a clipping unit configured to clip an output of the rectifier circuit;

a first schmitt trigger circuit configured to shape a waveform of an output of the clipping unit;

a differentiating circuit configured to differentiate an output of the first schmitt trigger circuit; and

a second schmitt trigger circuit configured to shape a waveform of an output of the differentiating circuit.

4. An illumination device comprising:

the lighting circuit according to claim 1; and

the illumination load.

5. A bulb-shaped LED lamp comprising the illumination device according to claim 4.