LED LIGHTING DEVICE

• US 20080157689A1
• Filed: 03/17/2008
• Published: 07/03/2008
• Est. Priority Date: 09/20/2005
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Kato, Akira
• Granted Patent: US 7,847,487 B2
• Time in Patent Office: Days
• US Class Current: 315/185S
• CPC Class Codes: H05B 45/30 Driver circuits
• CPC Class Codes: H05B 45/42 Antiparallel configurations
• CPC Class Codes: H05B 45/54 in a series array of LEDs

Abstract

Two LED arrays are connected in parallel, and the both ends of the parallel connection are connected to an alternating-current power supply AC. In each of the LED arrays, a capacitor and three LED blocks (the total of four components) are connected in series. In each of the LED blocks, two LEDs are connected in opposite directions. Connection points between components included in one of the two LED arrays are individually connected to connection points between components included in the other one of the two LED arrays via varistors. Even in the event that a disconnection failure occurs at any one of the LEDs, a path of a current via one of the varistors is formed for another one of the LEDs which is connected in series to the LED at which the disconnection failure has occurred. This can prevent the other LEDs from being turned off. Even in the event that a short-circuit failure occurs at any one of the varistors, the normal lighting operations of the LEDs can be maintained unless the LEDs have defects.

Claims

1. An LED lighting device comprising a plurality of LED arrays that are connected in parallel,

said plurality of LED arrays all having the same configuration in which a plurality of components including at least two LED blocks are connected in series, and

wherein respective elements having a bidirectional breakdown voltage are connected between pairs of connection points having the same order in two respective LED arrays, each of the connection points connecting two of the plurality of components, at least one of which is one of the LED blocks.

2. The LED lighting device according to claim 1, wherein the LED blocks each include a single LED, and the LEDs of all of the LED blocks are arranged in the same direction.

3. The LED lighting device according to claim 2, wherein at least one of the plurality of components included in each of the plurality of LED arrays is a resistor.

4. The LED lighting device according to claim 1,

wherein at least one of the plurality of components included in each of the plurality of LED arrays is a capacitor, and

wherein the LED blocks each have two LEDs connected in parallel in opposite directions.

5. The LED lighting device according to any one of claims 1 to 4, wherein the element having a bidirectional breakdown voltage is a varistor.

6. The LED lighting device according to any one of claims 1 to 4, wherein the element having a bidirectional breakdown voltage includes two Zener diodes connected in series in opposite directions.

7. The LED lighting device according to any one of claims 1 to 4, wherein the element having a bidirectional breakdown voltage includes two diodes connected in parallel in opposite directions.

8. The LED lighting device according to any one of claims 1 to 4, wherein a breakdown voltage of the element having a bidirectional breakdown voltage is substantially the same as a forward voltage drop of each of the LED blocks.