CN101281728A - Adaptive Gamma Conversion Voltage Switching Method and Device - Google Patents

Abstract

The invention discloses an adaptive gamma conversion voltage switching method and an adaptive gamma conversion voltage switching device. The quantization unit obtains quantized luminance data from the video data. The adaptive gamma voltage switching core dynamically adjusts the gamma conversion voltage according to the quantized brightness data to output the gamma conversion voltage to the panel, so that the panel alternately presents a black insertion picture and an adaptive contrast dynamic picture. Not only enhances the picture contrast, reduces the picture blur, but also improves the problem of insufficient brightness caused by picture black insertion.

Description

Adaptive Gamma Conversion Voltage Switching Method and Device

technical field

The present invention relates to a switching method and its device, and in particular to an adaptive gamma conversion voltage switching method and its device.

Background technique

With the vigorous development of Liquid Crystal Display (LCD), consumers have higher and higher requirements for LCD. Not only do they require products to be light in weight and small in size, but they also require bright colors and clear and bright images. In response to the needs of modern people, various manufacturers have developed many technologies to improve the quality of picture presentation.

Take Thin-Film Transistor Liquid Crystal Display (TFT-LCD) as an example. In the current technology, for the application of dynamic image quality improvement, the main improvement targets can be divided into color (Color) processing, contrast enhancement (Contrast Enhancement), and blur reduction (Blurreduce).

FIG. 1 depicts a circuit block diagram of a conventional gradation reference voltage device. Please refer to FIG. 1 , the existing gradation reference voltage device is mainly composed of a control board (Control Board) 11 and a source driver integrated circuit (SourceDriver Integrated Circuit) 12. Wherein the control board 11 includes a timing controller (TimingController, TCON) 113 and a series resistance and buffer unit (Resistance-string and Buffers) 115, in order to receive video data (Video Data), and send out video data and match appropriate control signal to drive the source driver circuit 12.

FIG. 2 depicts a circuit diagram of a conventional series resistor and a buffer unit. FIG. 3 depicts a graph of an existing fixed gamma curve. Please refer to Figure 2 and Figure 3. Generally, the gradation reference voltage of a traditional TFT-LCD is formed by dividing the voltage by resistors connected in series. The tone reference voltage cannot be changed after the series resistor is set. Because the resistance value of the voltage divider has been fixed, the gamma (Gamma) characteristic curve is fixed and cannot be changed. However, in the conventional technology, only a set of gradation voltage values of the gamma characteristic curve is provided to the source drive circuit 12, and then output to the panel 21 by the source drive circuit 12, so no matter what screen is used, the specified gamma in FIG. 3 is used. Mal characteristic curve as adjustment. Moreover, there is no mechanism for judging images on the traditional architecture, so it is impossible to make appropriate gamma curve adjustments according to the display characteristics of dynamic images. In short, the main disadvantage of this architecture is that the brightness of colors cannot be properly represented in dynamic images, and this disadvantage will greatly reduce the display quality.

In image processing, blur reduction is also one of the important topics, and common blur reduction techniques include Over Drive, Black Insertion (BI) and Optically Self-Compensated Birefringence (Optically self-Compensated) Birefringence, OCB)...etc. Since the premise of using overdrive is a fixed gamma characteristic curve, the overdrive technique cannot be used when the gamma curve is not fixed. It also makes it quite difficult to use the gamma characteristic curve to enhance the dynamic picture and reduce blur in the dynamic picture.

There are two ways to insert black on the screen: data insert black and backlight insert black. In terms of black data insertion, the method is to alternately display the normal picture data and black picture data of the TFT-LCD in two picture frames, or allocate and display them in one picture frame. There are two types of backlight insertion, one of which is TFT-LCD backlight blinking on and off (Blinking/Flash Backlight); the other is TFT-LCD backlight sequential on and off (Scanning Backlight). However, the disadvantage of backlight insertion black is that it needs to increase the hardware structure for controlling the backlight, which increases the cost; reducing the life of the backlight component and the backlight turn-on time need to accurately match the response characteristics of the liquid crystal, and the adjustment is not easy. Not only that, no matter whether you use data plug-in black or backlight plug-in black, it will cause the problem of weakened brightness. How to effectively compensate for the lack of brightness is also the problem.

In U.S. Patent Publication No. US2006/0017682, an OCB display driving device is proposed, which utilizes a power supply control circuit to provide an independent screen black reference voltage and image reference voltage to the source driver to improve and increase the screen black insertion rate. The problem that causes the brightness and contrast of the screen to decrease. However, it must provide an independent voltage to achieve black screen insertion, which not only increases the complexity of the circuit, but also requires more cost.

In view of this, the relevant manufacturers of the panel are eager to find a suitable solution to overcome the above-mentioned problems.

Contents of the invention

The purpose of the present invention is to provide an adaptive gamma conversion voltage switching method for enhancing contrast and reducing picture blur, thereby improving display effect.

Another object of the present invention is to provide an adaptive gamma conversion voltage switching device for enhancing contrast and reducing image blur, thereby improving display effect.

According to the above purpose, the present invention proposes an adaptive gamma conversion voltage switching method, the adaptive gamma conversion voltage switching method includes the following steps: counting video data to obtain a quantized brightness data of the video data. A gamma conversion voltage is dynamically adjusted according to the quantized luminance data to provide video data converted by the gamma conversion voltage. Switching the gamma switching voltage causes the panel to insert a black picture.

According to the above objectives, the present invention further proposes an adaptive gamma conversion voltage switching device, the adaptive gamma conversion voltage switching device includes a quantization unit and a gamma switching unit. The quantization unit obtains the quantized brightness data of the video data by counting the brightness cumulative distribution function of the video data. The adaptive gamma voltage switching core dynamically adjusts the gamma conversion voltage according to the quantized brightness data to provide the gamma conversion voltage to the digital-to-analog conversion unit, wherein the digital-to-analog conversion unit converts video data according to the gamma conversion voltage, so that the panel alternates Present the black-inserted picture and adapt to the contrast dynamic picture.

Because the present invention has the structure of dynamically adjusting the gamma conversion voltage, it can adjust the strength of the contrast data, increase the visual brightness, and improve the quality of the dynamic picture. Not only has the advantage of dynamic contrast enhancement, but also reduces blur by inserting black in the screen, and also compensates for the lack of brightness caused by black inserting in the screen.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments are exemplified below and described in detail with accompanying drawings.

Description of drawings

FIG. 1 depicts a circuit block diagram of a conventional gradation reference voltage device.

FIG. 2 depicts a circuit diagram of a conventional series resistor and a buffer unit.

FIG. 3 depicts a graph of an existing fixed gamma curve.

FIG. 4 depicts a circuit block diagram of a liquid crystal display driving circuit including an adaptive gamma switching voltage switching device according to an embodiment of the present invention.

FIG. 5A depicts a circuit block diagram of an adaptive gamma voltage switching core 427 according to an embodiment of the present invention.

FIG. 5B depicts a block diagram of the circuit and peripheral circuits of the adaptive gamma voltage switching core 427 according to an embodiment of the present invention.

FIG. 6 depicts a control signal waveform diagram of the adaptive gamma voltage switching device 42 according to an embodiment of the present invention.

Figure 7 depicts a graph of tone versus output brightness for a preferred embodiment of the present invention.

FIG. 8 depicts a circuit block diagram of a liquid crystal display driving circuit including an adaptive gamma switching voltage switching device according to another embodiment of the present invention.

FIG. 9A depicts a circuit block diagram of an adaptive gamma voltage switching core 827 according to an embodiment of the present invention.

FIG. 9B depicts a block diagram of the circuit and peripheral circuits of the adaptive gamma voltage switching core 827 according to an embodiment of the present invention.

FIG. 10 depicts another relationship diagram of tone versus output brightness according to an embodiment of the present invention.

Detailed ways

FIG. 4 depicts a circuit block diagram of a liquid crystal display driving circuit including an adaptive gamma conversion voltage switching device according to an embodiment of the present invention. Please refer to FIG. 4, the liquid crystal driving circuit includes a timing controller (Timing Controller, TCON) 411, a panel 413, a digital analog converter (Digital Analog Converter, DAC) unit 415, an adjustable backlight (Backlight) unit 417, an adaptive gamma Voltage switching device (Adaptive GammaVoltage Switching Device) 42, light sensor (Light Sensor) 421. The timing controller 411 is coupled to the panel 413 to provide control signals and data required for the display of the panel 413 , and the panel 413 is used for displaying data. The data includes video data (Video Data). The digital-to-analog conversion unit 415 is used for adjusting different gamma characteristic curves according to different display images, converting digital signal data into voltages for driving pixels, and converting the digital signal provided by the adaptive gamma voltage switching device 42 The gradation voltage data is converted into analog gradation voltage data and output to the source driving circuit of the panel 413 .

The light sensor 421 on the panel 413 is coupled to the adaptive gamma voltage switching device 42, the light sensor 421 is used to detect the brightness of the display screen of the panel 413, and can detect gray level (Gray Level)/brightness Insufficient problem, and output the brightness information to the adaptive gamma voltage switching device 42 . The adjustable backlight unit 417 is coupled between the panel 413 and the adaptive gamma voltage switching device 42, and is responsible for receiving the brightness control signal processed by the adaptive gamma voltage switching device 42 to adjust the brightness of the backlight to compensate the panel 413 Insufficient gray level/brightness caused by black insertion in the screen.

It should be noted that the adaptive gamma voltage switching device (Adaptive Gamma Voltage Switching Device) 42 further includes a histogram extraction unit (Histogram Extraction) 423, a quantization unit (Equalization) 425, an adaptive gamma voltage switching core (Adaptive Gamma VoltageSwitching Device) Core (referred to as AGVS) 427, arithmetic unit (Arithmetic) 429. The histogram extraction unit (Histogram Extraction) 423 is responsible for extracting the histogram from the input video data to obtain statistical probability distribution function (Probability Distribution Function, PDF) data. The quantization unit 425 is coupled to the histogram extraction unit 423, and the quantization unit 425 obtains a cumulative distribution function (Cumulative Distribution Function, CDF) data by using PDF data statistics. Then, according to the CDF data, mapping data of input tone to output tone after contrast modulation can be obtained. Then output the input tone-to-output tone mapping data to the adaptive gamma voltage switching core 427 . In other words, the adaptive gamma voltage switching core 427 dynamically adjusts the gamma conversion voltage according to the quantized brightness data, and provides the gamma conversion voltage to the digital-to-analog conversion unit 415 . The digital-to-analog conversion unit 415 converts the video data according to the gamma conversion voltage, so that the panel 413 alternately presents black-inserted images and adaptive contrast dynamic images. The above is to analyze the dynamic picture in this way, and then to give appropriate contrast enhancement with the changes of different pictures.

In the above adaptive gamma voltage switching device, the adaptive gamma voltage switching core 427 not only synchronously receives timing data (Vertical Sync, Dena) and the brightness information detected by the light sensor 421 on the panel 413, but also receives contrast modulated The input tone-to-output tone mapping data for . After the adaptive gamma voltage switching core 427 processes the above data, it generates brightness control signals, voltage mapping data for alternately displaying contrasting dynamic images/interpolated black images, and digital-to-analog (DAC) control signals. The brightness control signal can control the adjustable backlight unit 417, which is used to compensate the problem of insufficient brightness caused by black insertion in the picture.

The DAC control signal is used to control whether the digital-to-analog conversion unit 415 is enabled or not, so that the digital-to-analog conversion unit 415 converts digital scaled voltage data into analog scaled voltage data. The arithmetic unit (Arithmetic) 429 is coupled between the adaptive gamma voltage switching core 427 and the digital-to-analog conversion unit 415, and the arithmetic unit 429 alternates the adaptive contrast dynamic picture/interpolated black picture generated by the adaptive gamma voltage switching core 427 The displayed voltage mapping data is processed to generate a digital tone reference voltage, which is sequentially output to the digital-to-analog conversion unit 415 . Next, the internal architecture of the adaptive gamma voltage switching core 427 will be further described in detail below.

FIG. 5A depicts a circuit block diagram of an adaptive gamma voltage switching core 427 according to an embodiment of the present invention. FIG. 5B depicts a block diagram of the circuit and peripheral circuits of the adaptive gamma voltage switching core 427 according to an embodiment of the present invention. Please refer to FIG. 5A and FIG. 5B . The adaptive gamma voltage switching core 427 includes an optical engine (Optical Engine) 4271, a black insertion switching device (BI Switch Device) 4273, a control signal generator (CtrlSignal Generator) 4275 and a voltage input and output corresponding (Vin/Vout Mapping) unit 4277. The optical engine 4271 provides a brightness control signal to the adjustable backlight unit 417 after receiving brightness information from the light sensor 421 to adjust the brightness of the backlight. After receiving the timing data, the black insertion switching device 4273 outputs the black insertion switching signal BI Ctrl. The voltage input and output corresponding unit 4277 is coupled with the black insertion switching device 4273, and it outputs the tone data and the black insertion switching signal BI Ctrl of the black insertion switching device 4273 according to the input tone pair after the contrast modulation of the received quantization unit 425 , and output the voltage mapping data adapted to alternately display the contrasting dynamic picture/interpolated black picture to the computing unit 429 . The control signal generator 4275 synchronously outputs the DAC control signal to the digital-to-analog conversion unit 415 to control whether the digital-to-analog conversion unit 415 is enabled or not.

FIG. 6 depicts a control signal waveform diagram of the adaptive gamma voltage switching device 42 according to an embodiment of the present invention. Please refer to Figure 6. When the black insertion switching signal BI Ctrl is a logic 1, the panel 413 will present a black picture; otherwise, when the black insertion switching signal BI Ctrl is a logic 0, the panel 413 will present a dynamic picture for adaptive contrast. In other words, the adaptive gamma voltage switching device 42 will generate a picture enabling signal according to the timing data and the black insertion switching signal BI Ctrl, so that the display screen alternately presents the black insertion picture and the adaptive contrast dynamic picture, so as to achieve the effect of enhancing contrast and reducing blur.

Figure 7 depicts a graph of tone versus output brightness for a preferred embodiment of the present invention. Please refer to Figure 7. Curve A is the basic curve, that is, the gamma curve of the image without contrast enhancement. Due to the brightness compensation technology provided by the light sensor, the situation of adapting to contrasting dynamic images can be divided into two curves. The first is Curve B and the other is Curve C. Curve B is an adaptive contrast dynamic curve without brightness adjustment, and it can be clearly seen that its brightness is brighter than curve A. Curve C is an adaptive contrast dynamic curve with brightness adjustment. Since the optical engine 4271 directly adjusts the adjustable backlight unit 417, although the brightness of the curve C is brighter than that of the curve B, the brightness saturation near the boundary of the curve is poorer. Curve D is an interpolated black curve, which can also be said to be a gamma conversion voltage with a value of zero. When the black insertion switching signal BI Ctrl is logic 1, use the curve D to make the output brightness 0. In other words, the picture presents a black picture at this time, so as to provide black interpolation of the picture. The above not only provides dynamic picture contrast enhancement, but also cooperates with the black screen insertion technology to reduce blur, and at the same time compensates for the lack of brightness caused by the black screen insertion.

Those skilled in the art can also change the implementation according to the spirit of the present invention and the foregoing embodiments according to their needs. Another embodiment is listed below to describe the present invention in detail. FIG. 8 depicts a circuit block diagram of a liquid crystal display driving circuit including an adaptive gamma conversion voltage switching device according to another embodiment of the present invention. The liquid crystal driving circuit includes a timing controller 811 , a panel 813 , a digital-to-analog conversion unit 815 , an adjustable backlight unit 817 , an adaptive gamma voltage switching device 82 , and a light sensor 821 . The difference between this embodiment and the previous embodiments lies in the structure of the adaptive gamma voltage switching core 827. The structure of this embodiment not only improves the problem of insufficient brightness of black insertion, but also solves the problem of brightness saturation. The method is not to directly control the adjustable backlight unit 817, but to adjust the dynamic contrast intensity to compensate the problem of insufficient brightness of the panel 813 caused by black insertion in the screen, and to improve the brightness saturation problem of the backlight. Next, the adaptive gamma voltage switching core 827 will be further described in detail.

FIG. 9A depicts a circuit block diagram of an adaptive gamma voltage switching core 827 according to an embodiment of the present invention. FIG. 9B depicts a block diagram of the circuit and peripheral circuits of the adaptive gamma voltage switching core 827 according to an embodiment of the present invention. Please refer to FIG. 9A and FIG. 9B . The adaptive gamma voltage switching core 827 includes an optical engine 8271 , a black insertion switching device 8273 , a control signal generator 8275 and a voltage input and output corresponding unit 8277 . The optical engine 8271 receives the luminance information of the light sensor 821 and outputs a luminance compensation voltage to the voltage input and output corresponding unit 8277 . The voltage input and output corresponding unit 8277 is based on the brightness compensation voltage and the black insertion switching signal BI Ctrl of the black insertion switching device 8273, so as to compensate the brightness of the contrast dynamic picture and output the voltage mapping data suitable for the contrast dynamic picture/black insertion alternate display. In other words, the optical engine 8271 is responsible for processing the obtained brightness information and converting it into the contrast modulation input tone-to-output tone mapping value required by the voltage input and output corresponding unit 8277, directly compensating the problem of insufficient brightness caused by black insertion in the screen , and solve the problem of brightness saturation caused by the adjustable backlight unit 817.

FIG. 10 depicts another relationship diagram of tone versus output brightness according to an embodiment of the present invention. Curve A1 , curve B1 , and curve D1 are the same as those of the foregoing embodiment, and details are not repeated here. A1 is the basic dynamic compensation curve, B1 is the dynamic compensation adjustment, D1 is the black insertion curve, please refer to the curve C1. This embodiment is to receive the brightness information of the light sensor 821 on the panel 813 and output it to the input and output voltage for conversion. The corresponding unit 8277 directly and adaptively improves the contrast intensity and brightness compensation, avoiding the situation where the boundary value is distorted by directly adjusting the brightness, thus solving the problem of brightness saturation.

To sum up, the preferred embodiment of the present invention proposes a device for switching with adaptive gamma voltage, through controlling the output of the gamma switching voltage, the purpose of black insertion is achieved by switching the gamma switching voltage. The switching of the gamma conversion voltage is to achieve the purpose of switching the voltage by changing the mapping relationship between the input and output voltages. In addition, it cooperates with the light sensor to detect brightness data, and corrects the input-output voltage mapping relationship to adjust the intensity of contrast data, increase visual brightness, and improve the quality of dynamic images. Not only has the advantage of dynamic contrast enhancement, but also reduces blur by inserting black in the screen, and also compensates for the lack of brightness caused by black inserting in the screen.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection should be defined by the claims.

Claims (12)

1. adaptability gamma conversion voltage changing method, this adaptability gamma conversion voltage changing method may further comprise the steps:

Add up a video signal data and quantize brightness data to obtain one of this video signal data;

Dynamically adjust a gamma conversion voltage according to this quantification brightness data and change this video signal data so that this gamma conversion voltage to be provided; And

Switching this gamma conversion voltage makes this panel insert a black plug picture.

2. adaptability gamma conversion voltage changing method as claimed in claim 1 is characterized in that, by changing input and output voltage mapping relations to reach switched voltage.

3. adaptability gamma conversion voltage changing method as claimed in claim 1 is characterized in that, also comprises the light that this panel of sensing shows, and obtains a monochrome information, and adjust a backlight assembly according to this monochrome information.

4. adaptability gamma conversion voltage changing method as claimed in claim 1 is characterized in that, also comprises the light that this panel of sensing shows, and obtains a monochrome information, and adjust this gamma switched voltage according to this monochrome information.

5. adaptability gamma conversion voltage changing method as claimed in claim 1 is characterized in that, this quantification brightness data is obtained by following steps:

The histogram that extracts this video signal data obtains a brightness probability distribution function;

Add up this brightness probability distribution function and obtain a brightness cumulative distribution function; And

Calculate this brightness cumulative distribution function and obtain this quantification brightness data.

6. adaptability gamma conversion voltage switching device shifter, this adaptability gamma conversion voltage switching device shifter comprises:

One quantifying unit obtains one of this video signal data by the brightness cumulative distribution function of adding up a video signal data and quantizes brightness data; And

One adaptability gamma voltage switches core, dynamically adjust a gamma conversion voltage to provide this gamma conversion voltage according to this quantification brightness data to a D/A conversion unit, wherein this D/A conversion unit is changed this video signal data according to this gamma conversion voltage, uses to make a panel alternately present black plug picture and adaptation contrast dynamic menu.

7. adaptability gamma conversion voltage switching device shifter as claimed in claim 6 is characterized in that, it is that zero gamma conversion voltage is used and made this panel present the black plug picture that this D/A conversion unit receives one group of numerical value.

8. adaptability gamma conversion voltage switching device shifter as claimed in claim 6 is characterized in that, also comprises:

One first light sensor, the light that this panel of this first light sensor sensing shows, and obtain a monochrome information, and adjust a backlight assembly according to this monochrome information.

9. adaptability gamma conversion voltage switching device shifter as claimed in claim 8 is characterized in that, this adaptability gamma voltage switches core and comprises:

One light engine, receiving provides after this monochrome information a brightness control signal to use the backlight illumination of adjusting this backlight assembly to a backlight assembly;

One black plug switching device shifter, receive a time series data after, export a black plug switching signal;

One control signal generator, receive this time series data after, the output control signal is given this D/A conversion unit, uses this D/A conversion unit of control and whether enables; And

The corresponding unit of one voltage input and output is coupled to this black plug switching device shifter and this quantifying unit, and it is according to this black plug switching signal of this black plug switching device shifter, and output adapts to the voltage mapping (enum) data of contrast dynamic menu/black plug picture Alternation Display.

10. adaptability gamma conversion voltage switching device shifter as claimed in claim 6 is characterized in that, also comprises:

One second light sensor, the light that this panel of this second light sensor sensing shows, and obtain a monochrome information, and adjust this gamma switched voltage that this adaptability gamma voltage switches core according to this monochrome information.

11. adaptability gamma conversion voltage switching device shifter as claimed in claim 10 is characterized in that, this adaptability gamma voltage switches core and comprises:

One light engine receives after this monochrome information and exports a luminance compensation voltage;

One black plug switching device shifter, receive a time series data after, export a black plug switching signal;

One control signal generator, receive this time series data after, the output control signal is given this D/A conversion unit, uses this D/A conversion unit of control and whether enables; And

The corresponding unit of one voltage input and output, be coupled to this black plug switching device shifter, this quantifying unit and this light engine, receive this luminance compensation voltage and this black plug switching signal, use compensation and adapt to the brightness of contrast dynamic menu and the voltage mapping (enum) data that output adapts to contrast dynamic menu/black plug picture Alternation Display.

12. adaptability gamma conversion voltage switching device shifter as claimed in claim 6 is characterized in that, also comprises:

One Nogata acquisition unit, this Nogata acquisition unit counts this brightness probability distribution function by this video signal data and then tries to achieve a brightness cumulative distribution function, and this quantifying unit obtains this quantification brightness data by this brightness cumulative distribution function.

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