DRIVING CIRCUIT OF LIGHT-EMITTING DIODE, AND LIGHT-EMITTING DEVICE AND LIGHTING DEVICE USING THE SAME

• Main Author: SAKAMOTO YASUMASA
• Format: Patent
• Language: English
• Published: 10.03.2011
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

PROBLEM TO BE SOLVED: To drive an LED by stable luminance relative to the fluctuation of a power supply voltage. SOLUTION: The driving circuit 100 drives an LED array 2 including a plurality of LEDs 4 connected in series. A power source 30 supplies a driving voltage Vdrv to the LED array 2. A first transistor 12 and a first resistor R1 are provided in series between the second terminal P2 of the LED array 2 and a reference voltage terminal P3 on the driving route of the LED array 2. A contact current source 16 is provided between the second terminal P2 of the LED array 2 and the control terminal of the first transistor 12. A second transistor 14 is provided between the control terminal of the first transistor 12 and the reference voltage terminal, and a voltage corresponding to the voltage drop VR1 of the first resistor R1 is applied to the control terminal. COPYRIGHT: (C)2011,JPO&INPIT