# US 10,120,236 B2 · Liquid crystal display driving circuit and liquid crystal display device

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- Number: US 10,120,236 B2
- Document ID: US10120236B2
- Status: Granted
- Kind: B2
- Application number: 15/118,880
- Filed: 2016-06-29
- Published: 2018-06-21
- Granted: 2018-11-06
- Earliest claimed: 2016-06-17
- Assignees: Wuhan China Star Optoelectronics Technology Co., Ltd.
- Applicants: Wuhan China Star Optoelectronics Technology Co., Ltd.
- Inventors: Xingling Guo; Xiang Yang; Jiehui Qin
- Web page: https://patentgrep.com/patent/US10120236B2

## CPC

- G02F 1/133611: {including means for improving the brightness uniformity}
- G09G 3/36: using liquid crystals
- G09G 3/3607: {for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels (display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127)}
- G09G 3/3611: {Control of matrices with row and column drivers}
- G02F 1/1336: {Illuminating devices}
- G02F 2203/30: Gray scale
- G09G 3/3406: {Control of illumination source (illumination devices structurally associated with liquid crystal cells G02F1/1336)}
- G09G 2310/0264: Details of driving circuits
- G09G 2320/0276: for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
- G09G 2320/0646: Modulation of illumination source brightness and image signal correlated to each other
- G09G 2320/0673: for control of gamma adjustment, e.g. selecting another gamma curve
- G09G 2330/021: Power management, e.g. power saving
- G09G 2360/145: the light originating from the display screen
- G09G 2360/16: Calculation or use of calculated indices related to luminance levels in display data
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)

## Abstract

The disclosure provides a liquid crystal display driving circuit and a liquid crystal display device. The liquid crystal display driving circuit includes a content adaptive brightness control circuit and a Gamma voltage adjustment circuit, when the content adaptive brightness control circuit is turned on, the brightness of the backlight module is switched from first backlight brightness to second backlight brightness under the control of the content adaptive brightness control circuit, when the brightness of the backlight module is the first backlight brightness, the Gamma voltage adjustment circuit outputs a first Gamma voltage for adjusting grayscale brightness of the liquid crystal display to be first grayscale brightness, when the brightness of the backlight module is the second backlight brightness, the Gamma voltage adjustment circuit outputs a second Gamma voltage for adjusting the grayscale brightness of the liquid crystal display to be second grayscale brightness.

## Claims

### Claim 1

A liquid crystal display driving circuit, wherein the liquid crystal display driving circuit comprises a content adaptive brightness control circuit and a Gamma voltage adjustment circuit, the content adaptive brightness control circuit is applied to adjust a brightness of a backlight module in a liquid crystal display, when the content adaptive brightness control circuit is turned on, the brightness of the backlight module is switched from a first backlight brightness to a second backlight brightness under control of the content adaptive brightness control circuit, where the first backlight brightness is brighter than the second backlight brightness, when the brightness of the backlight module is the first backlight brightness, the Gamma voltage adjustment circuit outputs a first Gamma voltage for adjusting a grayscale brightness of the liquid crystal display to be a first grayscale brightness, when the brightness of the backlight module is the second backlight brightness, the Gamma voltage adjustment circuit outputs a second Gamma voltage for adjusting the grayscale brightness of the liquid crystal display to be a second grayscale brightness, where the second grayscale brightness is brighter than the first grayscale brightness, and a brightness of an output image from the liquid crystal display when the grayscale brightness of the liquid crystal display is the second grayscale brightness and the brightness of the backlight module is the second backlight brightness is equal to the brightness of the output image from the liquid crystal display when the grayscale brightness of the liquid crystal display is the first grayscale brightness and the brightness of the backlight module is the first backlight brightness,
wherein, the Gamma voltage adjustment circuit comprises a Gamma curve feedback circuit, a control circuit, a storage circuit and a Gamma voltage output circuit, the control circuit is electrically connected between the storage circuit and the Gamma voltage feedback circuit, the Gamma curve feedback circuit is applied to detect the grayscale brightness of the liquid crystal display to be the second grayscale brightness when the brightness of the backlight module is switched from the first backlight brightness to the second backlight brightness, and transport the second grayscale brightness to the control circuit, the control circuit obtains the second Gamma voltage corresponding to the second grayscale brightness from the storage circuit according to the second grayscale brightness, and exports the second Gamma voltage by the Gamma voltage output circuit.

### Claim 2 (depends on 1)

The liquid crystal display driving circuit according to claim 1, wherein when the content adaptive brightness control circuit is turned off, the brightness of the backlight module in the liquid crystal display is constant, when the content adaptive brightness control circuit is turned off, the Gamma voltage adjustment circuit is not operational so that the grayscale brightness of the liquid crystal display is the first grayscale brightness.

### Claim 3 (depends on 1)

The liquid crystal display driving circuit according to claim 1, wherein the Gamma voltage adjustment circuit further comprises a line buffer and a D/A converter, the line buffer is applied to receive a RGB subpixel serial grayscale signal, and transform the RGB subpixel serial grayscale signal to a RGB subpixel parallel grayscale signal, where the RGB subpixel serial grayscale signal is a serial signal, the RGB subpixel parallel grayscale signal is a parallel signal, the D/A converter is applied to convert an analog Gamma voltage generated by the Gamma voltage output circuit to a digital Gamma voltage according to the RGB subpixel parallel grayscale signal, and export the digital Gamma signal to a corresponding pixel electrode in the liquid crystal display.

### Claim 4 (depends on 3)

The liquid crystal display driving circuit according to claim 3, wherein the Gamma voltage adjustment circuit further comprises a level shifter, the level shifter is applied to receive the RGB subpixel parallel grayscale signal, and export the RGB subpixel parallel grayscale signal after its voltage being boosted to the D/A converter.

### Claim 5

A liquid crystal display device, wherein the liquid crystal display device comprises a liquid crystal display and a liquid crystal display driving circuit, the liquid crystal display driving circuit comprises a content adaptive brightness control circuit and a Gamma voltage adjustment circuit, the content adaptive brightness control circuit is applied to adjust a brightness of a backlight module in a liquid crystal display, when the content adaptive brightness control circuit is turned on, the brightness of the backlight module is switched from a first backlight brightness to a second backlight brightness under control of the content adaptive brightness control circuit, where the first backlight brightness is brighter than the second backlight brightness, when the brightness of the backlight module is the first backlight brightness, the Gamma voltage adjustment circuit outputs a first Gamma voltage for adjusting a grayscale brightness of the liquid crystal display to be a first grayscale brightness, when the brightness of the backlight module is the second backlight brightness, the Gamma voltage adjustment circuit outputs a second Gamma voltage for adjusting the grayscale brightness of the liquid crystal display to be a second grayscale brightness, where the second grayscale brightness is brighter than the first grayscale brightness, and a brightness of an output image from the liquid crystal display when the grayscale brightness of the liquid crystal display is the second grayscale brightness and the brightness of the backlight module is the second backlight brightness is equal to the brightness of the output image from the liquid crystal display when the grayscale brightness of the liquid crystal display is the first grayscale brightness and the brightness of the backlight module is the first backlight brightness,
wherein, the Gamma voltage adjustment circuit comprises a Gamma curve feedback circuit, a control circuit, a storage circuit and a Gamma voltage output circuit, the control circuit is electrically connected between the storage circuit and the Gamma voltage feedback circuit, the Gamma curve feedback circuit is applied to detect the grayscale brightness of the liquid crystal display to be the second grayscale brightness when the brightness of the backlight module is switched from the first backlight brightness to the second backlight brightness, and transport the second grayscale brightness to the control circuit, the control circuit obtains the second Gamma voltage corresponding to the second grayscale brightness from the storage circuit according to the second grayscale brightness, and exports the second Gamma voltage by the Gamma voltage output circuit.

### Claim 6 (depends on 5)

The liquid crystal display device according to claim 5, wherein when the content adaptive brightness control circuit is turned off, the brightness of the backlight module in the liquid crystal display is constant, when the content adaptive brightness control circuit is turned off, the Gamma voltage adjustment circuit is not operational so that the grayscale brightness of the liquid crystal display is the first grayscale brightness.

### Claim 7 (depends on 5)

The liquid crystal display device according to claim 5, wherein the Gamma voltage adjustment circuit further comprises a line buffer and a D/A converter, the line buffer is applied to receive a RGB subpixel serial grayscale signal, and transform the RGB subpixel serial grayscale signal to a RGB subpixel parallel grayscale signal, where the RGB subpixel serial grayscale signal is a serial signal, the RGB subpixel parallel grayscale signal is a parallel signal, the D/A converter is applied to convert an analog Gamma voltage generated by the Gamma voltage output circuit to a digital Gamma voltage according to the RGB subpixel parallel grayscale signal, and export the digital Gamma signal to a corresponding pixel electrode in the liquid crystal display.

### Claim 8 (depends on 7)

The liquid crystal display device according to claim 7, wherein the Gamma voltage adjustment circuit further comprises a level shifter, the level shifter is applied to receive the RGB subpixel parallel grayscale signal, and export the RGB subpixel parallel grayscale signal after its voltage being boosted to the D/A converter.