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US 2003/0169226 A1Published application
Backlight control device for liquid crystal display
AssigneeSeiko Epson Corporation
InventorAtsushi Yamada
Life of this patent
Estimating the term…
Abstract
A backlight control device for a liquid crystal display includes a light emitting diode (LED) driving circuit that is connected to a power supply circuit and drives the LED, and a current control device that detects brightness around the liquid crystal display and controls a driving current for the LED according to the detected brightness.
Claims20
A backlight control device for a liquid crystal display, comprising:
- a light emitting diode (LED) driving circuit that is connected to a power supply circuit and drives the LED;
- and
- a current control device that detects brightness around the liquid crystal display and controls a driving current for the LED according to the detected brightness.
A backlight control device for a liquid crystal display, comprising:
- a light emitting diode (LED) driving circuit that is connected to a power supply circuit and drives the LED;
- a control reference voltage generation circuit that, for compensating for temperature dependency of luminescent brightness of the LED, generates a control reference voltage according to temperature characteristics of the luminescent brightness;
- and
- a voltage-current conversion circuit that converts the control reference voltage of the control reference voltage generation circuit to a predetermined current, wherein the LED driving circuit drives the LED by a driving current according to the predetermined current that is converted by the voltage-current conversion circuit.
1 more element
The backlight control device for a liquid crystal display, comprising:
- a light emitting device (LED) driving circuit that is connected to a power supply circuit and drives the LED;
- a first current control device that detects brightness around the liquid crystal display and controls a driving current of the LED according to the detected brightness:
- and
- a second current control device that, for compensating for temperature dependency of luminescent brightness of the LED, controls a driving current of the LED according to temperature characteristic of the luminescent brightness.
1 more element
A backlight control device for a liquid crystal display, comprising:
- a light emitting diode (LED) driving circuit that is connected to a power supply circuit and drives the LED;
- a control reference voltage generation circuit that is responsive to brightness around the liquid crystal display, and for compensating for temperature dependency of luminescent brightness of the LED, generates a control reference voltage according to temperature characteristics of the luminescent brightness;
- an error amplifier circuit that generates a signal representing a difference between a detection voltage generated according to a drive current of the LED and the control reference voltage generated by the control reference voltage generation circuit;
- and
- a voltage-current conversion circuit that converts the control reference voltage to a predetermined current,
- wherein the power supply circuit varies an output voltage thereof according to an output of the error amplifier circuit, and
- the LED driving circuit drives the LED by a driving current according to the predetermined current that is converted by the voltage-current conversion circuit.
4 more elements
A backlight control device for a liquid crystal display, comprising:
- a plurality of light emitting diode (LED) driving circuits that are connected to a power supply circuit and drive the corresponding respective plurality of LEDs;
- a control reference voltage generation circuit tat is responsive to the brightness around the liquid crystal display, and for compensating for temperature dependency of luminescent brightness of each of the LEDs, generates a control reference voltage according to temperature characteristics of the luminescent brightness;
- a control reference voltage level conversion circuit that converts the control reference voltage generated by the control reference voltage generation circuit to a lower level voltage and outputs the same;
- an error amplifier circuit that generates a signal representing a difference between each detection voltage generated according to each drive current of each of the LEDs of the respective LED driving circuits;
- and
- a plurality of current control circuits that each converts the control reference voltage converted by the control reference voltage level conversion circuit to a predetermined current, and controls the drive current of each of the LEDs of the respective LED driving circuits to assume the predetermined current, wherein
- the power supply circuit varies an output voltage thereof according to an output of the error amplifier circuit.
4 more elements
A backlight control device for a liquid crystal display, comprising:
- a light emitting diode (LED) driving circuit that is connected to a power supply circuit and drives the LED;
- and
- means for detect brightness around the liquid crystal display and controlling a driving current for the LED according to the detected brightness.
19 A backlight control device for a liquid crystal display, comprising:
- a light emitting diode (LED) driving circuit that is connected to a power supply circuit and drives the LED;
- means for generating a control reference voltage according to temperature characteristics of the luminescent brightness for compensating for temperature dependency of luminescent brightness of the LED;
- and
- means for converting the control reference voltage of the mean for generating to a predetermined current, wherein the LED driving circuit drives the LED by a driving current according to the predetermined current that is converted by the voltage-current conversion circuit.
1 more element
The backlight control device for a liquid crystal display according to claim 19, wherein the means for generating is composed of a band-gap reference circuit.
Dependencies are inferred from the claim text.