Light Emitting Device

• US 20080037303A1
• Filed: 08/09/2007
• Published: 02/14/2008
• Est. Priority Date: 08/10/2006
• Status: Active Grant

• Current Assignee: Hayashi Chemical Industry Co., Ltd.
• Original Assignee: Hayashi Chemical Industry Co., Ltd.
• Inventors: Mishimagi, Kazuharu
• Granted Patent: US 7,777,421 B2
• Time in Patent Office: Days
• US Class Current: 363/131
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]

Abstract

An object of the invention is to suppress the amount of heat generated by a light emitting diode and prevent the light emitting diode from being overheated without reducing the amount of emitted light even when the light emitting diode is a high-power light emitting diode. A light emitting device is configured so that one or more light emitting diodes 11 are lighted by a lighting circuit 12. A DC power is converted into a pulse power by a switching regulator 13 of this lighting circuit 12 and the voltage of a pulse power converted by this switching regulator is lowered by an output control portion 14. The pulse width of a pulse power lowered in voltage by this output control portion is adjusted by a pulse width adjusting oscillation means 16, and the current of a pulse power adjusted in pulse width by this pulse width adjusting oscillation means is limited by a limiting resistor 17. The light emitting device is configured so that a pulse power limited in current by this limiting resistor is outputted to a light emitting diode.

Claims

1. A light emitting device comprising one or more light emitting diodes (11) and a lighting circuit (12) for lighting said light emitting diodes (11), wherein;

said lighting circuit (12) has;

a switching regulator (13) for converting a DC power into a pulse power,

an output control portion (14) for lowering the voltage of a pulse power converted by said switching regulator (13),

a pulse width adjusting oscillation means (16) for adjusting the pulse width of a pulse power lowered in voltage by said output control portion (14), and

a limiting resistor (17) for limiting in current a pulse power adjusted in pulse width by said pulse width adjusting oscillation means (16) and outputting the pulse power to said light emitting diodes (11).

2. The light emitting device according to claim 1, wherein said output control portion (14) has a first resistor (14a) one end of which is connected to a compared voltage input of a voltage comparator (13b) of said switching regulator (13) and the other end of which is grounded through a waveform shaping capacitor (14c), and a second resistor (14b) one end of which is connected to the compared voltage input of said voltage comparator (13b) and the other end of which is grounded, wherein said first resistor (14a) has a resistance value of 3.0 kΩ

to 9.0 kΩ

, said second resistor (14b) has a resistance value of 1.0 kΩ

to 2.0 kΩ

, the ratio of the resistance value of said first resistor (14a) to the resistance value of said second resistor (14b) is 1.5 to 9.0, and said limiting resistor (17) has a resistance value of 1.0Ω

to 100.0Ω

.

3. The light emitting device according to claim 1, wherein said light emitting diode (11) has a forward current of 100 mA to 1000 mA, a pulse forward current of 200 mA to 2000 mA, an allowable reverse current of 50 mA to 250 mA, a power dissipation of 1.0 to 8.0 W, an operating temperature of −

30 to 85°

C., a storage temperature of −

40 to 100°

C., and a dice temperature of 80 to 160°

C.

4. A method for suppressing the amount of heat generated;

by a light emitting diode without reducing the amount of light emitted comprising using the light emitting diode of claim 1.

5. The method of claim 4 using the light emitting diode of claim 2.

6. The method of claim 4 using the light emitting diode of claim 3.