US Patent No. 9,179,515

DRIVER CIRCUIT FOR LED BACKLIGHT OF LIQUID CRYSTAL DISPLAY DEVICE


Patent No. 9,179,515
Issue Date November 03, 2015
Title Driver Circuit For Led Backlight Of Liquid Crystal Display Device
Inventorship Yasuharu Aizawa, Yamanashi (JP)
Assignee FANUC CORPORATION, Yamanashi (JP)

Claim of US Patent No. 9,179,515

1. A driver circuit for an LED backlight of a liquid crystal display device, the driver circuit configured to supply a drive
current to the LED backlight, which has an LED, in accordance with a PWM signal used for controlling an amount of the drive
current supplied to the LED backlight, the driver circuit comprising:
a determination unit configured
to receive the PWM signal,
to determine whether or not a duty ratio of the PWM signal exceeds a predetermined value set in advance,
to output a first luminance adjustment signal set in advance when the duty ratio of the PWM signal is below the predetermined
value or when there is no input of the PWM signal, and

to output a second luminance adjustment signal corresponding to the input PWM signal when the duty ratio of the PWM signal
exceeds the predetermined value; and

a drive current output unit configured,
when the determination unit outputs the first luminance adjustment signal,
to receive the first luminance adjustment signal from the determination unit, and
to supply the drive current corresponding to the first luminance adjustment signal to the LED backlight, and
when the determination unit outputs the second luminance adjustment signal,
to receive the second luminance adjustment signal from the determination unit, and
to supply the drive current corresponding to the second luminance adjustment signal to the LED backlight.