TWI381362B - Method and apparatus for displaying image on a display unit and controlling backlight module which irradiates the display unit - Google Patents

Description

Display device and brightness control method thereof

The present invention relates to a display device and a brightness control method thereof, and more particularly to a display device for controlling a backlight module according to a brightness analysis result of an image signal and a brightness control method thereof.

Among the many factors that determine the quality of a display, the contrast is a key factor, especially for liquid crystal displays (LCDs). Among them, such as the characteristics of the liquid crystal display panel, the quality of the image signal or the backlight of the liquid crystal display panel, etc., can affect the contrast value. Therefore, the industry has long been actively seeking ways to improve the contrast value of displays, and several related technologies have also been developed. However, traditional techniques have not effectively enhanced the contrast value.

The main object of the present invention is to provide a display device for controlling a backlight module and a brightness control method thereof according to the brightness analysis result of the image signal.

The invention discloses a display device comprising a receiving circuit, an image processing circuit, a display unit, a brightness analysis circuit, a backlight module and a backlight control unit. The receiving circuit is configured to process the received input signal to generate an image signal. The image processing circuit is coupled to the receiving circuit and configured to process the image signal to generate a driving signal. The display unit is coupled to the image processing circuit and displays the corresponding content of the image signal driven by the driving signal. The brightness analysis circuit is coupled to the receiving circuit and configured to analyze the image signal to generate a brightness analysis result. The backlight module is used to provide the backlight required by the display unit. The backlight control unit is coupled to the brightness analysis circuit and the backlight module, and is configured to generate a control signal to the backlight module according to the brightness analysis result to control the backlight module.

The invention further discloses a control circuit for controlling a display unit and a backlight module, wherein the backlight module is used to provide a backlight required by the display unit. The control circuit includes an image processing circuit, a brightness analysis circuit, and a backlight control unit. The image processing circuit is configured to receive and process an image signal including a plurality of image data, and the display unit is configured to display the image data. The brightness analysis circuit is configured to receive the image signal and analyze the brightness value of the image signal to generate a brightness analysis result. The backlight control unit is coupled to the brightness analysis circuit for generating a control signal to the backlight module according to the brightness analysis result to control the backlight module.

The present invention further discloses a brightness control method for a display device. The display device includes a display unit and a backlight module. The method controls the display unit to display the corresponding content of the image signal, and controls the backlight module to be provided to the display unit. Backlighting. The method comprises: (a) processing an image signal to generate a driving signal to drive the display unit; (b) displaying a corresponding content of the image signal; (c) analyzing the image signal to generate a brightness analysis result; and (d) analyzing the brightness according to the brightness As a result, a control signal is generated to the backlight module to control the backlight module.

Certain terms are used throughout the description and following claims to refer to particular elements. Those of ordinary skill in the art should understand that a hardware manufacturer may refer to the same component by a different noun. The scope of this specification and the subsequent patent application do not use the difference of the names as the means for distinguishing the elements, but the difference in function of the elements as the criterion for distinguishing. The term "including" as used throughout the specification and subsequent claims is an open term and should be interpreted as "including but not limited to". In addition, the term "coupled" is used herein to include any direct and indirect electrical connection. Therefore, if a first device is coupled to a second device, it means that the first device can be directly electrically connected to the second device or indirectly electrically connected to the second device through other devices or connection means.

Please refer to FIG. 1 , which is a schematic diagram of a display device according to a preferred embodiment of the present invention. The display device 100 includes a receiving circuit 110, a control circuit 120, a display unit 130, and a backlight module 140.

The receiving circuit 110 can receive the analog/digital format input signal by wire or wirelessly and process it to generate an image signal. The image signal includes a plurality of frame data, and each frame data includes parameter values (such as brightness values) of a plurality of pixels. The processing performed on the input signal includes, for example, down-converting, demodulating, or inputting a signal from an RF to an intermediate frequency or a base band. Processed in the digit format for analog format.

After processing, the receiving circuit 110 outputs the image signal to the control circuit 120. The control circuit 120 includes an image processing circuit 122, a brightness analysis circuit 124, and a backlight control unit 126. As shown in FIG. 1, the image processing circuit 122 is coupled to the receiving circuit 110 for receiving image signals and performing scaling, gamma correction, interpolation, and filtering. A general image processing operation such as filtering is performed, and then a driving signal is generated to the display unit 130. The display unit 130 displays the corresponding content of the image signal by sequentially displaying each screen data under the driving of the driving signal.

On the other hand, the brightness analysis circuit 124 also receives the image signal and performs an analysis operation to generate a brightness analysis result for each picture data according to the pixel brightness values of the picture data. The brightness analysis result of each picture data can be used as a reference for comparing the brightness level of the picture data. For example, the brightness analysis result may be a voltage signal or a current signal. For the brightness analysis result with higher signal intensity, the display unit 130 may display a higher overall picture brightness when displaying the corresponding picture data.

The backlight control unit 126 is coupled to the brightness analysis circuit 124 and the backlight module 140 for generating a control signal to the backlight module 140 according to the brightness analysis result to control the backlight intensity provided by the backlight module 140 to the display unit 130. The backlight module 140 includes two MOS transistors Q1, Q2, a transformer 142, a lamp tube 144, and a resistor 146. The gates of both transistors Q1 and Q2 receive control signals. The primary side of the transformer 142 is coupled to the two transistors Q1, Q2 and an input voltage Vin, and the secondary side is coupled to a ground terminal. The lamp 144 is coupled between the secondary side of the transformer 142 and the resistor 146 to generate light to the display unit 130.

In addition, in this embodiment, the control signal is a Pulse Width Modulation (PWM) signal. When the duty cycle of the PWM signal changes, the switching voltage of the secondary side of the transformer 142 also changes, thereby changing the brightness of the light emitted by the lamp 144. That is, the brightness of the lamp 144 (ie, the backlight size of the backlight module 140) can be adjusted by the control signal. The following is a detailed description of how the brightness analysis circuit 124 produces a brightness analysis result for the backlight control unit 126 to generate a control signal.

Please refer to FIG. 2, which is a schematic diagram of the brightness analysis circuit 124. The brightness analysis circuit 124 includes a brightness classification circuit 210, a calculation circuit 220, a brightness indicator analysis circuit 230, and a memory unit 240. The brightness classification circuit 210 is configured to receive the image signal, and divide the brightness values of the pixels of each picture data into a plurality of brightness levels. It is assumed that the pixel luminance value adopts a general 8-bit design, that is, 256 gray scales; in this embodiment, each of the 32 gray scales (256/8) is used as a luminance level, and eight luminance levels are obtained. Taking one of the screen data as an example, the distinguishing action of the brightness classification circuit 210 determines which brightness level the pixel values included in the pixel fall within, thereby generating the above-mentioned distinguishing action for each picture material. A brightness data. Specifically, the brightness data can be presented in the form of a histogram, as shown in FIG.

In the third figure, the horizontal axis represents the pixel brightness value, and the above-mentioned 256 gray scale is taken as an example, and each of the 32 gray levels is divided into a brightness level from small to large, and eight brightness levels of the same size can be obtained. The vertical axis represents the number of pixels that fall within each brightness level after a certain picture material is distinguished by the brightness classification circuit 210. For example, the number of pixels corresponding to the first brightness level (ie, the interval [0, 31]) is PN1, and the number of pixels corresponding to the eighth brightness level (ie, the interval [223, 255]) is PN8, and the other second to seventh brightness levels. The corresponding number of pixels is PN2~PN7 (not shown). The brightness data contains the results of each picture data as shown in Figure 3.

The calculation circuit 220 coupled to the brightness classification circuit 210 is configured to calculate the brightness data, such as: counting the values of PN1~PN8 of each picture data or calculating an average brightness value of each picture data. Taking Figure 3 as an example, the average brightness value avg_LV of this picture data can be defined as: (1):

In the embodiment, the calculation circuit 220 sets a certain PNi (i=1~8) or avg_LV of each picture data as one of the corresponding brightness indexes L_index, and the L_index represents a brightness characteristic of the corresponding picture data. In other embodiments, the brightness indicator may also be a set of values, including the number of PN1~PN8 and avg_LV, for example, L_index={PN1, avg_LV} may be defined. Next, the calculation circuit 220 outputs the obtained brightness index of each picture data to the brightness indicator analysis circuit 230.

The brightness indicator analysis circuit 230 analyzes the brightness indicator to generate a brightness analysis result for each picture data. The memory unit 240 coupled to the brightness indicator analysis circuit 230 stores a plurality of lookup tables corresponding to the brightness indicators. Depending on the brightness indicator definition of the calculation circuit 220 (which can be determined by the user), the brightness indicator analysis circuit 230 will generate a brightness analysis result based on different lookup tables. For example, the memory unit 240 can store three look-up tables L1, L2, and L3, respectively corresponding to the brightness indicators PN1, PN8, and avg_LV; that is, if the user decides to use PN1 as the brightness index, the brightness indicator analysis circuit 230 The lookup table L1 in the memory unit 240 is read to perform an analysis operation. In other embodiments, when the brightness indicator is a set of values, the brightness indicator analysis circuit 230 reads the corresponding lookup table based on the set of values. Taking L_index={PN1, avg_LV} as an example, the brightness index analysis circuit 230 reads the corresponding two-dimensional lookup table according to PN1 and avg_LV. As described above, the brightness analysis result may be a voltage signal or a current signal. For different brightness indicator values, the brightness indicator analysis circuit 230 generates brightness analysis results of different signal strengths according to the lookup table.

As shown in FIG. 1 , the backlight control unit 126 controls the backlight module 140 according to the brightness analysis result, that is, the backlight control unit 126 can dynamically adjust the backlight size of the backlight module 140 according to the brightness characteristics of each picture material. The case where PN1 is defined as a brightness index is taken as an example, and the adjustment mechanism is illustrated in the drawings.

Please refer to FIG. 4 , which is a relationship diagram between the brightness index and the backlight brightness of the backlight module 140 . The luminance index indicated by the horizontal axis is PN1, and the vertical axis represents the backlight control unit 126 adjusts the backlight module 140 to the corresponding backlight luminance according to the luminance analysis result obtained by the luminance index PN1. As shown in FIG. 4, when the brightness index PN1 varies between PNL and PNH with different picture data, the backlight brightness of the backlight module 140 will be negative between the two preset values BL and BH. The correlation is linearly adjusted to different sizes. That is, the larger (small) PN1, the lower the backlight brightness of the backlight module 140 will be adjusted (high). If the brightness index of a certain picture material is PN1 in FIG. 4, the backlight module 140 illuminates the display unit 130 with a backlight having a brightness of B1. Wherein, if PN1 is greater than PNH or smaller than PNL, the backlight brightness of the backlight module 140 will be adjusted to BL and BH, respectively. In this way, the larger picture data of PN1 (ie, the number of pixels with low brightness) will obtain lower backlight brightness and be displayed on the display unit 130, and the picture material with smaller PN1 (ie, the number of pixels with low brightness) will be obtained. The higher backlight brightness is displayed on the display unit 130, thereby improving the contrast of the display unit 130 when displaying the image signal. Of course, in other embodiments, when other brightness indicator definitions or hardware capabilities are taken into consideration, the relationship between the brightness index and the backlight brightness may also be designed to be different from the linear relationship of FIG. 4, such as a curve relationship or Adjust like a histogram.

Please refer to FIG. 5, which is a flow chart of a brightness control method according to a preferred embodiment of the present invention. First, an image signal is received (S510). As described above, the image signal includes a plurality of frame data, and each frame data includes parameter values (such as brightness values) of a plurality of pixels.

Next, the luminance values of the respective pixels are divided into a plurality of luminance levels to generate a luminance data (S520). As described above, in the embodiment, the luminance value range of the pixel is exemplified by 0 to 255 gray scales, and eight brightness levels are distinguished by small to large gray scales, and the pixels of each picture data are used. That is, the brightness level is distinguished according to the brightness value. Therefore, the brightness data of each picture material can be expressed by the histogram of FIG.

Then, the brightness data is calculated to generate a brightness indicator (S530). As described above, the brightness indicator may be the number of pixels corresponding to any brightness level, for example, the number of pixels corresponding to the first brightness level PN1; or one of the picture data average brightness value avg_LV (as defined by equation (1)); or include PN1 A set of values for the number of ~PN8 and avg_LV, such as {PN1, PN8} or {PN1, avg_LV}.

Next, the brightness indicator is analyzed to generate a brightness analysis result (S540). As described above, the brightness indicator can be defined in a manner that produces a brightness analysis result based on an appropriate lookup table.

Finally, the backlight intensity of the backlight module is adjusted according to the brightness analysis result (S550). As described above, depending on the actual application considerations such as the definition of the brightness indicator and the hardware computing capability, the backlight module can be controlled by various adjustment mechanisms. For example, a linear relationship as shown in Figure 4, or other non-linear approach. Therefore, with different picture materials (luminance analysis results), the backlight brightness of the backlight module can be dynamically adjusted to an appropriate size, thereby effectively improving the image quality of the image signal.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

100‧‧‧ display device

110‧‧‧ receiving circuit

120‧‧‧Control circuit

122‧‧‧Image Processing Circuit

124. . . Brightness analysis circuit

126. . . Backlight control unit

130. . . Display unit

140. . . Backlight module

142. . . transformer

144. . . Lamp

146. . . resistance

210. . . Brightness classification circuit

220. . . Calculation circuit

230. . . Brightness index analysis circuit

240. . . Memory unit

Q1, Q2 MOS. . . Transistor

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of a display device in accordance with a preferred embodiment of the present invention.

FIG. 2 is a schematic diagram of the brightness analysis circuit 124.

Figure 3 is a histogram representing the luminance data.

FIG. 4 is a graph showing the relationship between the brightness index and the backlight brightness of the backlight module 140.

Figure 5 is a flow chart of a brightness control method in accordance with a preferred embodiment of the present invention.

Claims (9)

A display device includes: a receiving circuit for processing an input signal received to generate an image signal; an image processing circuit coupled to the receiving circuit for processing the image signal to generate a driving signal; a display unit coupled to the image processing circuit, wherein the display unit is driven by the driving signal to display the corresponding content of the image signal; a brightness analysis circuit coupled to the receiving circuit and configured to analyze the image signal to generate a brightness analysis result, wherein the brightness analysis circuit comprises: a brightness classification circuit for receiving the image signal, and dividing the brightness value of each pixel into a plurality of brightness levels to generate a brightness data; a calculation circuit, coupling The brightness classification circuit is configured to calculate a minimum number of pixels of the brightness level and an average value of brightness values of all pixels in a picture data, and generate a brightness indicator, wherein the brightness indicator includes the brightness levels The number of the pixels of the one and the average of the brightness values of all the pixels in the picture material And a brightness index analysis circuit, coupled to the calculating circuit configured to generate the brightness analysis result of the analysis of the brightness of a look-up table index, wherein the analysis result is simultaneously brightness based on the brightness level of these One of the number of the pixels and the average of the brightness values of all the pixels in the picture data; a backlight module for providing the backlight required by the display unit, including a first MOS a transistor, a second MOS transistor, a transformer, a lamp, and a resistor, wherein the transformer is coupled to the first MOS transistor, the second MOS transistor, a voltage source, and a ground, and the lamp The switch is coupled between the transformer and the resistor; and a backlight control unit coupled to the brightness analysis circuit and the backlight module, and configured to generate a control signal to the backlight module according to the brightness analysis result to control The backlight module, wherein the first MOS transistor and the second MOS transistor receive the control signal at gate terminals of the first MOS transistor and the second MOS transistor, respectively. The display device of claim 1, wherein the control signal is a Pulse Width Modulation (PWM) signal, and the PWM signal controls the backlight brightness of the backlight module. The display device of claim 2, wherein the duty cycle of the PWM signal is determined according to the brightness analysis result. A control circuit for controlling a display unit and a backlight module, wherein the backlight module provides a backlight required by the display unit and includes a first MOS transistor, a second MOS transistor, a transformer, and a lamp tube And a resistor, wherein the transformer is coupled to the first MOS transistor, the second transistor, a voltage source, and a ground, and the lamp is coupled between the transformer and the resistor, the control circuit includes An image processing circuit for receiving and processing an image signal including a plurality of image data, wherein the display unit is configured to display the image data; and a brightness analysis circuit is configured to receive the image signal and analyze the image signal a brightness value to generate a brightness analysis result, wherein the brightness analysis circuit includes: a brightness classification circuit for receiving the image signal, and dividing the brightness value of each pixel into a plurality of brightness levels to generate a brightness data a calculation circuit coupled to the brightness classification circuit for calculating a minimum number of pixels of the brightness level and an average value of brightness values of all pixels in a picture data, and for generating a brightness indicator, the brightness indicator includes The number of the pixels of one of the brightness levels and the average of the brightness values of all of the pixels in the picture material And a brightness indicator analysis circuit coupled to the calculation circuit and configured to analyze the brightness indicator according to a lookup table to generate the brightness analysis result, wherein the brightness analysis result is based on the pixel of one of the brightness levels The number and the average of the brightness values of all of the pixels in the picture material are generated; a backlight control unit coupled to the brightness analysis circuit for generating a control signal to the backlight module according to the brightness analysis result to control the backlight module, wherein the first MOS transistor and the second MOS device The crystal receives the control signal at the gate terminals of the first MOS transistor and the second MOS transistor, respectively. The control circuit of claim 4, wherein the control signal is a pulse width modulation (PWM) signal, and the PWM signal can control the backlight brightness of the backlight module. The control circuit of claim 5, wherein the duty cycle of the PWM signal is determined according to the brightness analysis result. A brightness control method for a display device, the display device comprising a display unit and a backlight module, wherein the method controls the display unit to display a corresponding content of an image signal, and controls the backlight module to be provided to the display unit The backlight intensity includes: (a) processing the image signal to generate a driving signal to drive the display unit; (b) displaying the corresponding content of the image signal; (c) analyzing the image signal to generate a brightness analysis a result, wherein the step (c) comprises: dividing the luminance value of each pixel into a plurality of brightness levels Generating a brightness data; calculating a number of pixels of the brightness level and an average value of brightness values of all pixels in a picture material; and generating a brightness indicator, the brightness indicator including the pixel of one of the brightness levels The number and the average value of the brightness values of all the pixels in the picture data; and analyzing the brightness indicator according to a lookup table to generate the brightness analysis result, wherein the brightness analysis result is based on the brightness levels simultaneously And the number of the pixels and the average of the brightness values of all the pixels in the picture data are generated; and (d) generating a control signal to the backlight module according to the brightness analysis result to control the backlight The module, wherein the backlight module includes a first MOS transistor, a second MOS transistor, a transformer, a lamp, and a resistor, wherein the transformer is coupled to the first MOS transistor and the second a transistor, a voltage source, and a ground, and the lamp is coupled between the transformer and the resistor. The method of claim 7, wherein the control signal is a pulse width modulation (PWM) signal, and the PWM signal controls the backlight brightness of the backlight module. The method of claim 8, wherein the step (d) The method includes: determining a duty cycle of the PWM signal according to the brightness analysis result.