Brightness adjustment device and method, LED backlight device and liquid crystal display device
A brightness adjustment and brightness technology, applied in the fields of brightness adjustment methods, circuits, LED backlight devices and liquid crystal display devices, can solve the problems of affecting the dimming accuracy, large voltage difference, affecting the accuracy of the error signal amplifier backlight adjustment current, etc. The effect of smooth adjustment and power consumption reduction
Active Publication Date: 2015-01-21
BOE TECH GRP CO LTD +1
View PDF9 Cites 3 Cited by
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Problems solved by technology
[0004] Due to the limitation of the manufacturing process, there will be a voltage difference of about 20mV between the positive input terminal and the negative input terminal of the error signal amplifier in practice. The general reference voltage V ref The value will be around 200mV. When the duty ratio D of the external PWM square wave signal is 1, the error of 20mV can be ignored; when the duty ratio D is low, for example, D is 20% or 10%. , V ref The value of ×D is only 40mV or 20mV. At this time, the voltage difference between the positive input terminal and the negative input terminal of the error signal amplifier will become very large, which will affect the backlight regulation current I output by the error signal amplifier. led accuracy, which affects the dimming accuracy
Method used
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View moreImage
Smart Image Click on the blue labels to locate them in the text.
Smart ImageViewing Examples
Examples
Experimental program
Comparison scheme
Effect test
Embodiment Construction
[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.
[0039] Such as figure 2 As shown, the brightness adjustment device of the LED backlight circuit described in the embodiment of the present invention includes:
[0040] Duty ratio detection unit 21, for detecting the duty ratio D of the external PWM square wave signal;
[0041] And, the brightness adjustment unit 22 is used for adjusting the backlight voltage V obtained by multiplying the rated voltage by the duty ratio D led , and according to the backlight...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More PUM
Login to View More Abstract
The invention provides a brightness adjustment method and circuit, an LED backlight device and a liquid crystal display device. The brightness adjustment device of an LED backlight circuit comprises a duty ratio detection unit and a brightness adjustment unit. The duty ratio detection unit is used for detecting the duty ratio of an external PWM square signal. The brightness adjustment unit is used for adjusting the brightness of the LED backlight circuit according to backlight adjustment voltage obtained by multiplying nominal voltage by the duty ratio, wherein the nominal voltage is preset backlight adjustment voltage obtained when the duty ratio of the external PWM square signal is 100 percent. According to the brightness adjustment device and method, the duty ratio of the external PWM square signal is detected, output current is adjusted in real time according to detection results, in this way, backlight brightness is adjusted, and therefore smooth adjustment of backlight brightness within the full range can be realized; besides, when the duty ratio is low, power consumption can be effectively reduced.
Description
technical field [0001] The invention relates to the field of display technology, in particular to a brightness adjustment method, a circuit, an LED backlight device and a liquid crystal display device. Background technique [0002] In the existing liquid crystal display device, the PWM (Pulse Width Modulation, pulse width modulation) dimming technology of the LED light emitting diode (LED) backlight circuit can effectively adjust the brightness of the backlight, but there are also defects and deficiencies, such as Generally, the PWM technology can only ensure the output current with a certain accuracy when the duty ratio D is above 50%, and the accuracy also decreases when the duty ratio decreases. [0003] Such as figure 1 As shown, the existing brightness adjustment device of the LED backlight circuit includes an error signal amplifier 11, a diode LED, and a brightness adjustment resistor R. The external PWM square wave signal used for brightness adjustment is connected t...
Claims
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More Application Information
Patent Timeline
Login to View More Patent Type & Authority Applications(China)
IPC IPC(8): G09G5/10
Inventor 王谦陈志勇王秀荣
Owner BOE TECH GRP CO LTD