LED power supply

Patent metadata

Field	Value
Publication number	US-9345100-B2
Application number	US-201514612350-A
Country	US
Kind code	B2
Filing date	Feb 3, 2015
Priority date	Mar 28, 2014
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

A no-load detection circuit includes an inductance device, an impedance device and a switch circuit. The inductance device is interposed between a choke coil and a first output terminal, which is at a high potential side, so as to be magnetically coupled to the choke coil. The impedance device is connected in series with the inductance device between the inductance device and the first output terminal. The switch circuit is configured to be turned on when a value of electric potential at the first output terminal exceeds a predetermined reference value. The control circuit is configured to stop the switching control if the switch circuit is turned on.

First claim

The invention claimed is:

1. An LED power supply, comprising:
a power converter circuit comprising first and second output terminals between which a load comprising an LED is detachably connected;
a control circuit configured to control the power converter circuit; and
a no-load detection circuit configured to detect presence of a no-load condition in which the load is not connected between the first and second output terminals, wherein
the power converter circuit comprises a chopper converter comprising a switching device and a choke coil,
the control circuit is configured to perform switching control of the switching device, and to stop the switching control if the no-load detection circuit detects the presence of the no-load condition,
the no-load detection circuit comprises an inductance device, an impedance device and a switch circuit, the inductance device being interposed between the choke coil and the first output terminal, which is at a high potential side, so as to be magnetically coupled to the choke coil, the impedance device being connected in series with the inductance device between the inductance device and the first output terminal, the switch circuit being configured to be turned on when a value of electric potential at the first output terminal exceeds a predetermined reference value, and
the control circuit is configured to stop the switching control if the switch circuit is turned on.

2. The LED power supply of claim 1 , further comprising a control power supply circuit configured to supply activation electric power to the control circuit, wherein
the switch circuit is configured to maintain an on-state thereof until a main current is equal to or less than a predetermined lower limit after being turned on so that the main current is supplied from the control power supply circuit.

3. The LED power supply of claim 2 , wherein
the control circuit comprises a universal integrated circuit configured to perform the switching control of the switching device, and
the control circuit is configured so that a signal, at a terminal of two or more terminals with which the integrated circuit is provided, is driven high while the integrated circuit functions properly and driven to low when the switch circuit is turned on.

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Ueda Keisuke
• Ukita Nobuo

Classifications

• H05B45/58

  involving end of life detection of LEDs · CPC title

• G09G2330/12

  Test circuits or failure detection circuits included in a display system, as permanent part thereof · CPC title

• H05B45/50

  responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits · CPC title

• H05B33/0875

  Electricity · mapped topic

• H05B33/0815

  Electricity · mapped topic