WO2011007503A1 - Led backlight control device, led backlight control method, led backlight control module, and display device - Google Patents

Abstract

Disclosed is an LED backlight control device, wherein a light intensity calculation unit (106) acquires DC coefficients which are DCT coefficients of a direct-current component corresponding to blocks which are to undergo orthogonal transformation, performing said acquiring from encoded data generated by encoding processing, which accompanies orthogonal transformation, being performed on a block-by-block basis in an image. Using the values obtained from k DC coefficients, a LED driver IC (110) controls the light intensity of an LED module, which corresponds to blocks that correspond to the k DC coefficients, among a plurality of LED modules included in a LED backlight module (112).

Description

LED backlight control device, LED backlight control method, LED backlight control module, and display device

The present invention relates to an LED backlight control device, an LED backlight control method, an LED backlight control module, and a display device that control an LED (Light Emitting Diode) backlight that is a kind of backlight for LCD (Liquid Crystal Display). .

Conventionally, cold cathode fluorescent lamps have been the mainstream light source for liquid crystal backlights. Most liquid crystal TVs that use cold cathode fluorescent lamps as backlights always turn on the backlight, which causes “black floating” due to light leakage of the liquid crystal panel. Since the cold-cathode tube is surface emitting, when adjusting the brightness of the image with the backlight, it was only possible to adjust the entire screen uniformly.

Products with LED backlights on LCDs used for displays in TVs, PC displays, mobile phones, car navigation systems, portable DVD players, etc. are expected to gradually spread.

¡LED is a monochromatic light source, so when used as a backlight, the color reproduction range is expanded. Light control can be performed independently for each LED and the light leakage can be considerably reduced by locally adjusting the contrast of the image, so that the contrast of the screen can be greatly increased. In addition, the reproducibility of gradation and gradation in the dark portion is enhanced.

Also, since the LED does not require a high voltage, the power supply unit can be simplified. In the field of battery-powered portable electronic devices, the majority of products use white LED backlights. At present, the luminance of the LED is lower than that of the cold cathode tube, but it is expected to exceed that of the cold cathode tube in the future. This leads to reduction of power consumption in combination with local brightness control of the screen.

Therefore, LED backlight control technology becomes important. Patent Documents 1, 2, and 3 and Non-Patent Documents 1 and 2 disclose LED backlight control techniques.

JP 2008-102379 A JP 2006-330338 A JP 2007-086390 A

The LED backlight can improve the image quality as the number of LEDs used increases. However, in order to control an LED backlight using many LEDs, a large amount of calculation required to control each LED becomes a problem.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an LED backlight control device and the like that can efficiently reduce the amount of calculation required for controlling the LED backlight. It is.

In order to solve the above-described problem, an LED backlight control device according to an aspect of the present invention is an LED (Light Emitting Diode) backlight used for displaying an image, and includes a plurality of LED modules using LEDs. Control LED backlight including. The LED backlight control device uses DCT (Discrete) of a DC component corresponding to a block to be orthogonally transformed from encoded data generated by performing encoding processing with orthogonal transformation on a block basis for a video. C of a plurality of LED modules using an acquisition unit that acquires k (integer of 1 or more) DC coefficients that are Cosine 係数 Transform) coefficients and a value obtained from the k DC coefficients acquired by the acquisition unit. A light amount control unit that controls the light amount of the LED module corresponding to the block corresponding to each DC coefficient.

That is, the acquisition unit is a DCT coefficient of a direct current component corresponding to a block to be orthogonally transformed from encoded data generated by performing encoding processing with orthogonal transformation on a block basis for a video. Obtain k DC coefficients. The light quantity control unit controls the light quantity of the LED module corresponding to the block corresponding to the k DC coefficients among the plurality of LED modules, using a value obtained from the k DC coefficients.

That is, in the control of the light amount of the LED module included in the LED backlight, the calculation amount necessary for the control of the LED backlight can be efficiently reduced by using the DC coefficient obtained from the encoded data.

Preferably, k is an integer equal to or greater than 2, and the LED backlight control device further includes a calculation unit that calculates a DC coefficient average value that is an average value of k DC coefficients, and the light amount control unit includes: The light amount of the LED module corresponding to the block corresponding to the DC coefficient average value is controlled using the DC coefficient average value calculated using the k DC coefficients or the value obtained from the DC coefficient average value. .

An LED backlight control method according to another aspect of the present invention is an LED backlight used for displaying an image, and an LED backlight control device that controls an LED backlight including a plurality of LED modules using LEDs. Do. The LED backlight control method uses a DCT coefficient of a DC component corresponding to a block to be orthogonally transformed from encoded data generated by performing encoding processing with orthogonal transformation on a block basis for a video. Using the acquisition step of acquiring k (integer greater than or equal to 1) DC coefficients and the value obtained from the k DC coefficients acquired in the acquisition step, k DC coefficients of a plurality of LED modules are obtained. A light amount control step for controlling the light amount of the LED module corresponding to the corresponding block.

Preferably, k is an integer equal to or greater than 2, and the LED backlight control method further includes a calculation step of calculating a DC coefficient average value that is an average value of k DC coefficients, The light amount of the LED module corresponding to the block corresponding to the DC coefficient average value is controlled using the DC coefficient average value calculated using the k DC coefficients or the value obtained from the DC coefficient average value. .

An LED backlight control module according to still another aspect of the present invention is an LED backlight used for displaying an image, and controls an LED backlight including a plurality of LED modules using LEDs. The LED backlight control module uses a DCT coefficient of a DC component corresponding to a block to be orthogonally transformed from encoded data generated by performing encoding processing with orthogonal transformation on a block basis for a video. Using an obtaining unit that obtains k (integer greater than or equal to 1) DC coefficients and a value obtained from the k DC coefficients obtained by the obtaining unit, k DC coefficients among a plurality of LED modules are obtained. A light amount control unit that controls the light amount of the LED module corresponding to the corresponding block.

Preferably, k is an integer equal to or greater than 2, and the LED backlight control module further includes a calculation unit that calculates a DC coefficient average value that is an average value of k DC coefficients, and the light amount control unit includes: The light amount of the LED module corresponding to the block corresponding to the DC coefficient average value is controlled using the DC coefficient average value calculated using the k DC coefficients or the value obtained from the DC coefficient average value. .

A display device according to still another aspect of the present invention is an LED backlight used for displaying an image, and controls an LED backlight including a plurality of LED modules using LEDs. The display device uses DCT coefficients of DC components corresponding to each of the blocks to be orthogonally transformed from encoded data generated by performing an encoding process involving orthogonal transformation on the video in units of blocks. Corresponding to k DC coefficients among a plurality of LED modules using an acquisition unit that acquires k (integer of 1 or more) DC coefficients and a value obtained from the k DC coefficients acquired by the acquisition unit A light amount control unit that controls the light amount of the LED module corresponding to the block to be performed.

Preferably, k is an integer equal to or greater than 2, and the display device further includes a calculation unit that calculates a DC coefficient average value that is an average value of k DC coefficients, and the display device includes k DCs. The light quantity of the LED module corresponding to the block corresponding to the DC coefficient average value is controlled using the DC coefficient average value calculated using the coefficient or a value obtained from the DC coefficient average value.

The present invention may be realized not only as such an LED backlight control method but also as a program that causes a computer to execute each step included in such an LED backlight control method. Further, the present invention may be realized as a computer-readable recording medium that stores such a program. Such a program may be distributed via a transmission medium such as the Internet.

Further, in the present invention, all or some of the plurality of components constituting such an LED backlight control device may be realized as a system LSI (Large Scale Integration).

According to the present invention, the amount of calculation required for controlling the LED backlight can be efficiently reduced.

FIG. 1 is a block diagram illustrating a configuration of a display device according to the first embodiment. FIG. 2 is a diagram illustrating a full HD video as an example. FIG. 3 is a diagram for explaining the configuration of one LED module according to the first embodiment. FIG. 4 is a diagram illustrating various values corresponding to the size of the light control area. FIG. 5 is a diagram illustrating data of luminance Y, color difference Cb, and color difference Cr corresponding to a macro block of the 4: 2: 0 format. FIG. 6 is a diagram for explaining the positional relationship between luminance and color difference. FIG. 7 is a block diagram illustrating a configuration of a video decoder as an example. FIG. 8 is a diagram showing a set of DCT coefficient groups. FIG. 9 is a diagram showing six sets of DCT coefficient groups. FIG. 10 is a block diagram illustrating a configuration of a video output processing unit as an example. FIG. 11 is a flowchart of DC coefficient group acquisition processing. FIG. 12 is a flowchart of the backlight control process. FIG. 13 is a diagram illustrating an arithmetic circuit as an example. FIG. 14 is a diagram illustrating three arithmetic circuits. FIG. 15 is a flowchart of the backlight control process A. FIG. 16 is an external view of a display device according to the first embodiment and a modification of the first embodiment. FIG. 17 is a block diagram showing a characteristic functional configuration of the LED backlight control device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<First Embodiment>
FIG. 1 is a block diagram illustrating a configuration of a display device 1000 according to the first embodiment. The display device 1000 is, for example, a liquid crystal digital television receiver (hereinafter referred to as a liquid crystal digital TV) including an LCD panel. For the sake of explanation, FIG. 1 shows a UHF antenna 101 that is not included in the display device 1000.

Referring to FIG. 1, a display device 1000 includes a digital tuner 102, a TS (Transport Stream) demultiplexer 103, a video decoder 104, a video output processing unit 105, a light amount calculation unit 106, an audio decoder 107, An audio output processing unit 108, an LCD display control unit 109, an LED backlight module 112, an LCD panel 113, a stereo speaker 114, and a CPU (Central Processing Unit) 115 are provided.

The display device 1000 includes an LED backlight control device 500 that controls the LED backlight module 112. The LED backlight control device 500 is a semiconductor system LSI (Large Scale Integration) realized as an SOC (System-On-a-Chip). That is, the LED backlight control device 500 is an LED backlight control module.

That is, the LED backlight control device 500 in the present embodiment is exemplified as one component incorporated in the display device 1000 as a liquid crystal digital TV.

The LED backlight control device 500 includes a digital tuner 102, a TS demultiplexer 103, a video decoder 104, a video output processing unit 105, a light amount calculation unit 106, an audio decoder 107, an audio output processing unit 108, and an LCD. A display control unit 109 and a CPU 115 are provided.

Note that DRAM, flash EEPROM, other passive components, and detailed control signals are not shown in FIG.

The CPU 115 controls each unit included in the LED backlight control device 500 based on the control program. The CPU 115 is also called an embedded microcomputer or MCU.

The UHF antenna 101 is an instrument for converting a digital TV broadcast wave (radio wave) into a digital broadcast signal as an electric signal. As an example, the digital broadcast signal is a broadcast signal according to ISDB (Integrated Services Digital Broadcasting) -T or ISDB-S standards. The broadcast signal according to ISDB-T is a terrestrial wave. The broadcast signal according to the ISDB-S standard is a satellite broadcast wave.

The digital broadcast signal includes, for example, a transport stream (TS (Transport Stream)) according to the MPEG (Moving Picture Experts Group) standard. In the transport stream, a video stream and an audio stream as ES (Elementary Stream) are multiplexed.

In the present embodiment, the video stream to be processed is a stream (encoded data) obtained by encoding a video signal in accordance with, for example, the MPEG-2 standard. That is, the processing target video stream is a stream (encoded data) generated by performing encoding processing with orthogonal transformation on a video in units of blocks.

Note that the video stream to be processed is not limited to MPEG-2, but other video coding standards such as H.264. It may be a stream encoded according to the H.264 / AVC standard.

The audio stream is a stream in which an audio signal is encoded in accordance with, for example, an AAC (Advance Audio Coding) standard. Note that the audio stream is not limited to the AAC standard, and may be a stream encoded according to another audio encoding standard.

In this embodiment, it is assumed that a video with full HD resolution can be obtained by decoding a video stream. In the following, video with full HD resolution is also referred to as full HD video. The full HD video is a video having a size of horizontal 1920 × vertical 1080 pixels.

FIG. 2 is a diagram showing a full HD video as an example.

Referring to FIG. 1 again, the LED backlight module 112 is disposed on the back surface of the LCD panel 113. Although details will be described later, the LED backlight module 112 irradiates the LCD panel 113 with light from the back surface of the LCD panel 113.

The LCD panel 113 is a display circuit that displays an image using light emitted from the LED backlight module 112. The LCD panel 113 includes m (an integer greater than or equal to 2) pixels for displaying an image.

Suppose that the LCD panel 113 is a panel capable of displaying full HD video as an example. In this case, the number m of pixels included in the LCD panel 113 is 2073600 from 1920 × 1080.

Note that the LCD panel 113 is not limited to a full HD video, and may be a panel capable of displaying a video with a resolution lower than 1920 × 1080 or a video with a resolution higher than 1920 × 1080.

Each pixel included in the LCD panel 113 includes an RGB color filter. Each pixel constituting the LCD panel 113 functions as a liquid crystal shutter that controls the degree of transmission of light emitted from the LED backlight module 112.

A video (for example, full HD video) composed of m pixels included in the LCD panel 113 is divided into p (integer of 2 or more) dimming areas. Here, the light control region is a region that is a unit of light control of the LED module described later. That is, the light control area is an area that is a unit for controlling the light amount of the LED module as the backlight.

In the present embodiment, it is assumed that the dimming area is an aggregate of blocks (hereinafter referred to as MPEG blocks) defined by the MPEG standard. An MPEG block is a block (macroblock) that is a processing unit of orthogonal transform (DCT operation). That is, the MPEG block is a block that is an object of orthogonal transformation. As shown in FIG. 2, the size of the MPEG block is assumed to be 8 × 8 pixels as an example.

The LED backlight module 112 includes p LED modules respectively corresponding to the p dimming regions. The LED module is a module using LEDs. The p LED modules are arranged in a matrix.

Each dimming area is composed of one or more MPEG blocks (macro blocks). That is, each dimming area corresponds to one or more MPEG blocks (macroblocks). That is, each MPEG block (macro block) corresponds to one dimming area. That is, each MPEG block (macro block) corresponds to one LED module.

For example, it is assumed that the dimming area size is 16 × 16 pixels and the MPEG block (macro block) size is 8 × 8 pixels. In this case, the dimming area corresponds to four MPEG blocks (macro blocks). In this case, each MPEG block (macro block) corresponds to one dimming area, that is, one LED module.

Next, the configuration of the LED module will be described.

FIG. 3 is a diagram for explaining the configuration of one LED module according to the first embodiment.

Referring to FIG. 3, R indicates an LED that emits red light (hereinafter referred to as a red LED). G indicates an LED that emits green light (hereinafter referred to as a green LED). B represents an LED that emits blue light (hereinafter referred to as a blue LED).

The LED module in the present embodiment includes a red LED, two green LEDs, and a blue LED. The red LED, the two green LEDs, and the blue LED constituting the LED module are arranged as shown in FIG.

Since the green LED has lower luminous efficiency than the red LED and the blue LED, two green LEDs are used in one LED module as shown in FIG.

The p LED modules included in the LED backlight module 112 emit light to the aforementioned p dimming regions. Thereby, the LED backlight module 112 can control an LED module independently for every light control area | region.

Here, FIG. 4 shows the relationship among the size of the light control area, the number of MPEG blocks, and the number of light control areas when the light control area is a square.

Referring to FIG. 4, the number of MPEG blocks indicates the number of MPEG blocks corresponding to the size of the dimming area. The number of MPEG blocks is indicated by the number of horizontal MPEG blocks and the number of vertical MPEG blocks. For example, when the size of the dimming area is 40 × 40 pixels, the number of MPEG blocks is 25 from 5 × 5.

Further, the number of light control areas indicates the number p of light control areas corresponding to the size of the light control areas. For example, when the size of the dimming area is 16 × 16 pixels, the number of dimming areas is 8100.

In the present embodiment, as an example, it is assumed that the size of the dimming area is 32 × 32 pixels. In this case, the number of light control areas is 2025. That is, the LED backlight module 112 includes 2025 LED modules.

Note that the dimming area is not limited to a square, and may be any shape that is an integral multiple of the block in the vertical and horizontal directions. When the size of each dimming area is increased, the number of LED modules necessary for the backlight can be reduced and the cost can be reduced. However, since the brightness of the backlight cannot be controlled for each fine area, the image quality deteriorates.

As described above, in this embodiment, it is assumed that a full HD video is obtained by decoding a video stream.

Full HD video is encoded in units of macroblocks in accordance with, for example, the MPEG-2 standard. Here, the macro block is the above-described MPEG block. That is, the macro block is a block that is an object of orthogonal transformation. The size of the macroblock is assumed to be 8 × 8 pixels. That is, a video stream is generated by encoding full HD video in units of macroblocks.

The video stream generated by the encoding of the MPEG-2 standard includes data obtained by encoding the luminance Y, color difference Cb, and color difference Cr data corresponding to each macroblock. In the present embodiment, it is assumed that each macroblock is a macroblock of 4: 2: 0 format.

In this case, the video stream to be processed includes, as an example, data on luminance Y, color difference Cb, and color difference Cr corresponding to each macroblock in the 4: 2: 0 format.

FIG. 5 is a diagram showing data of luminance Y, color difference Cb, and color difference Cr corresponding to a macro block of 4: 2: 0 format.

As shown in FIG. 5, the size of each color difference data is half the size of the luminance data in both the vertical and horizontal directions. That is, the information amount of each color difference data is 1/4 of the information amount of luminance data.

Further, the positional relationship between the luminance and the color difference with respect to the pixel is shown in FIG.

In FIG. 6, one luminance data corresponds to one pixel. On the other hand, one color difference data corresponds to four pixels.

Again referring to FIG. 1, UHF antenna 101 transmits a digital broadcast signal to digital tuner 102.

The digital tuner 102 is a tuning circuit. The digital tuner 102 obtains a demodulated signal by demodulating the digitally modulated digital broadcast signal. Then, the digital tuner 102 acquires a transport stream of the channel selected (designated) from the demodulated signal. The digital tuner 102 transmits the acquired transport stream to the TS demultiplexer 103.

The TS demultiplexer 103 acquires a video stream and an audio stream by performing a demultiplexing process on the transport stream. The TS demultiplexer 103 transmits the video stream and the audio stream to the video decoder 104 and the audio decoder 107, respectively.

The video decoder 104 acquires a video signal before encoding by decoding the video stream, and transmits the video signal to the video output processing unit 105. Specifically, the video decoder 104 performs the following processing.

FIG. 7 is a block diagram showing a configuration of the video decoder 104 as an example.

Referring to FIG. 7, the video decoder 104 includes an input buffer 201, a variable length decoding unit 202, an inverse quantization unit 203, an inverse DCT unit 204, an adder 205, a motion compensation unit 206, a frame memory. 207 and 208 and an output buffer 209.

In the video decoder 104, the processing performed in each unit other than the inverse quantization unit 203 is a decoding process according to the MPEG-2 standard, and therefore detailed description will not be repeated. A brief description is given below.

First, a video stream is stored in the input buffer 201. The variable length decoding unit 202 acquires decoded video data by decoding the video stream. The variable length decoding unit 202 transmits the motion vector to the motion compensation unit 206 every time a motion vector is obtained by the decoding process.

The inverse quantization unit 203 inversely quantizes the decoded video data in units of macroblocks. Here, it is assumed that the size of the macroblock is 8 × 8 pixels. As described above, it is assumed that the macroblock is a macroblock of 4: 2: 0 format. By this processing, six sets of DCT coefficient groups corresponding to the luminance Y, the color difference Cb, and the color difference Cr are obtained.

FIG. 8 is a diagram showing a set of DCT coefficient groups.

In FIG. 8, the DCT coefficient group is composed of 64 DCT coefficients. Of the 64 DCT coefficients, the DCT coefficient located at the upper left is a DCT coefficient (hereinafter referred to as a DC coefficient) of a DC (direct current) component. The DC coefficient is an average value of the pixel values of all the pixels in the corresponding block. Of the 64 DCT coefficients, DCT coefficients other than the DC coefficient are DCT coefficients of AC (alternating current) components.

6 sets of DCT coefficient groups obtained by the inverse quantization unit 203 performing inverse quantization on the decoded video data are shown below.

FIG. 9 is a diagram showing six sets of DCT coefficient groups.

In FIG. 9, blocks Y0, Y1, Y2, and Y3 each represent four sets of DCT coefficient groups. The four sets of DCT coefficient groups correspond to the luminance Y. That is, the inverse quantization unit 203 obtains four DC coefficients (hereinafter referred to as luminance DC coefficients) for the luminance Y.

Block Cb indicates a DCT coefficient group corresponding to the color difference Cb. That is, the inverse quantization unit 203 obtains one DC coefficient (hereinafter referred to as the first color difference DC coefficient) for the color difference Cb. A block Cr indicates a DCT coefficient group corresponding to the color difference Cr. That is, the inverse quantization unit 203 obtains one DC coefficient (hereinafter referred to as a second color difference DC coefficient) for the color difference Cr.

That is, the inverse quantization unit 203 obtains six DC coefficients (four luminance DC coefficients, first color difference DC coefficient, and second color difference DC coefficient) by inverse quantizing the decoded video data in units of macroblocks.

Referring again to FIG. 7, every time inverse quantization is performed in units of macroblocks, inverse quantization section 203 transmits six sets of DCT coefficient groups to inverse DCT section 204 and includes six DC coefficients ( Four luminance DC coefficients, a first color difference DC coefficient, and a second color difference DC coefficient) are transmitted to the light amount calculation unit 106.

Hereinafter, the six DC coefficients (four luminance DC coefficients, the first color difference DC coefficient, and the second color difference DC coefficient) corresponding to each macroblock are referred to as a block corresponding DC coefficient group.

That is, the inverse quantization unit 203 transmits a block-corresponding DC coefficient group to the light amount calculation unit 106 every time inverse quantization is performed in units of macroblocks.

The inverse DCT unit 204 obtains an image (hereinafter referred to as a first image) by performing an inverse DCT calculation process on each DCT coefficient group. Then, the inverse DCT unit 204 transmits the first image to the adder 205.

The motion compensation unit 206 performs motion compensation using a motion vector and an image (frame) stored in one of the frame memories 207 and 208. Then, the motion compensation unit 206 transmits an image obtained by motion compensation (hereinafter referred to as a second image) to the adder 205.

The adder 205 generates a frame (hereinafter referred to as a decoded frame) by synthesizing the first image and the second image. The decoded frame is stored in the output buffer 209. The decoded frame is stored in one of the frame memories 207 and 208.

By repeatedly performing the above processing, the output buffer 209 stores a plurality of decoded frames. Then, a video signal composed of a plurality of decoded frames is transmitted to the video output processing unit 105. The video signal transmitted to the video output processing unit 105 is a video signal in YCbCr format.

Referring to FIG. 1 again, the video output processing unit 105 performs video display processing on the received video signal. The video output processing unit 105 transmits the video signal subjected to the video display process to the LCD display control unit 109.

Specifically, the video output processing unit 105 performs the following processing.

FIG. 10 is a block diagram illustrating a configuration of the video output processing unit 105 as an example.

Referring to FIG. 10, video output processing unit 105 includes a video adjustment unit 301, a conversion unit 302, a multi-window processing unit 303, an OSD (On-Screen Display) composition unit 304, and an output buffer 305. .

Video display processing performed by the video output processing unit 105 includes video adjustment processing, conversion processing, multi-window processing, and OSD composition processing.

The video adjustment unit 301 receives a video signal from the video decoder 104. The video adjustment process is a process performed on the video signal received by the video adjustment unit 301. The video adjustment process is performed by the video adjustment unit 301.

In the image adjustment processing, contrast correction, γ correction, noise removal processing, and the like are performed. In the video adjustment processing, gradation processing, contour correction processing, and the like are further performed as necessary. The video signal subjected to the video adjustment process is transmitted to the conversion unit 302.

The conversion process is performed by the conversion unit 302. The conversion process is a process performed on the video signal received by the conversion unit 302.

In the conversion process, a color space conversion process is performed. The color space conversion process is YCbCr-RGB color conversion. YCbCr-RGB color conversion is performed based on Equation 1 below. Expression 1 is an expression based on the standard of Recommendation ITU-R BT.709 (Rec.709).
(Formula 1)
R '= 1.164 (Y-16) +1.596 (Cr-128)
G ′ = 1.164 (Y−16) −0.392 (Cb−128) −0.813 (Cr−128)
B ′ = 1.164 (Y−16) +2.017 (Cb−128)
In Equation 1, R ′, G ′, and B ′ represent R, G, and B that are γ-corrected.

By performing the color space conversion process, the YCbCr format video signal is converted into an RGB format video signal.

In the conversion process, frame rate conversion, resizing process, IP conversion, and the like are further performed as necessary. The video signal that has been subjected to the conversion process is transmitted to the multi-window processing unit 303.

Multi-window processing is performed by the multi-window processing unit 303. The multi-window process is a process performed on the video signal received by the multi-window processing unit 303. In multi-window processing, PoutP processing, PinP processing, thumbnail processing, and the like are performed as necessary. The video signal that has been subjected to the multi-window process is transmitted to the OSD synthesis unit 304.

The OSD synthesis process is performed by the OSD synthesis unit 304. The OSD synthesis process is a process performed on the video signal received by the OSD synthesis unit 304. In the OSD composition processing, superimpose processing, text broadcasting processing, graphic display processing, and the like are performed as necessary. The video signal that has undergone the OSD synthesis process is stored in the output buffer 305.

Then, the video signal stored in the output buffer 305 is transmitted to the LCD display control unit 109.

The LCD display control unit 109 is a digital signal processing circuit. The LCD display control unit 109 includes an LED driver IC 110 and an LCD driver IC 111.

The LCD driver IC 111 performs control for causing the LCD panel 113 to display a video based on the video signal received from the video output processing unit 105.

The audio decoder 107 acquires the audio signal before encoding by decoding the audio stream received from the TS demultiplexer 103, and transmits the acquired audio signal to the audio output processing unit 108.

The audio output processing unit 108 is an acoustic output circuit. The audio output processing unit 108 performs an audio process on the received audio signal to generate an acoustoelectric signal. The audio processing includes processing for adjusting the audio of the audio signal, processing for controlling the volume and stereo balance of the audio signal, and the like. The audio output processing unit 108 transmits the generated acoustoelectric signal to the stereo speaker 114.

The stereo speaker 114 converts the acoustoelectric signal into a sound wave.

Although the details will be described later, the light amount calculation unit 106 calculates a value for setting the light amount of the backlight.

The LED driver IC 110 is a circuit that controls the light emission of the LED backlight module 112 in accordance with the video to be displayed, details of which will be described later.

Note that the display device 1000 may receive a wired broadcast through a cable such as a coaxial cable or an optical cable instead of the UHF antenna 101. In this case, a digital set top box connected to the cable is positioned instead of the UHF antenna 101.

Further, a stream stored in a storage medium such as a DVD or HDD may be played back on the display device 1000. In this case, a PS (program stream) is read from a DVD player or the like instead of the TS transmitted from the digital tuner 102. In this case, the display device 1000 is provided with a PS demultiplexer instead of the TS demultiplexer 103.

Next, processing for controlling the corresponding LED module for each dimming area (referred to as backlight control processing) will be described.

First, a process for acquiring a block-corresponding DC coefficient group composed of the above-described six DC coefficients (hereinafter referred to as a DC coefficient group acquiring process) will be described.

FIG. 11 is a flowchart of DC coefficient group acquisition processing.

In step S111, the inverse quantization unit 203 obtains a block-corresponding DC coefficient group including six DC coefficients by inversely quantizing the decoded video data in units of macroblocks as described above. That is, the inverse quantization unit 203 included in the video decoder 104 inversely quantizes the decoded video data obtained from the video stream as the encoded data in units of macroblocks, thereby four luminance DC coefficients and the first color difference DC. The coefficient and the second color difference DC coefficient are obtained. That is, the video decoder 104 acquires one or more DC coefficients corresponding to the block to be orthogonally transformed from the encoded data.

In step S112, the inverse quantization unit 203 transmits the block-corresponding DC coefficient group to the light amount calculation unit 106.

11 is repeatedly performed every time the inverse quantization unit 203 performs inverse quantization in units of macroblocks.

FIG. 12 is a flowchart of the backlight control process.

In step S211, the light quantity calculation unit 106 acquires the block-corresponding DC coefficient group from the inverse quantization unit 203.

In step S212, it is determined whether or not the light quantity calculation unit 106 has acquired all the block-corresponding DC coefficient groups corresponding to the u (integer greater than or equal to 1) th dimming area among the p dimming areas described above. judge. The initial value of u is 1.

As described above, in the present embodiment, as an example, the size of the light control region is assumed to be 32 × 32 pixels. In this case, the number of light control areas is 2025. For example, when u is 10, in step S212, it is determined whether or not all the block-corresponding DC coefficient groups corresponding to the 10th dimming area among 2025 dimming areas have been acquired.

In this case, the LED backlight module 112 includes 2025 LED modules. Here, it is assumed that the size of the macroblock is 8 × 8 pixels. Therefore, when the size of the dimming area is 32 × 32 pixels, all the block-corresponding DC coefficient groups corresponding to the dimming area are four sets of block-corresponding DC coefficient groups respectively corresponding to the four macroblocks.

That is, in this case, when the light intensity calculation unit 106 acquires four sets of block-corresponding DC coefficient groups by performing the process of step S211 four times, all the block-corresponding DC coefficients corresponding to the u-th dimming region It is determined that the group has been acquired.

If YES in step S212, the process proceeds to step S213. On the other hand, if NO at step S212, the process at step S211 is performed again. Here, it is assumed that the light quantity calculation unit 106 has acquired all the block-corresponding DC coefficient groups corresponding to the u-th dimming area by performing the process of step S211 four times, and the process proceeds to step S213.

When the size of the dimming area is 8 × 8 pixels, all block-corresponding DC coefficient groups corresponding to the dimming area are a set of block-corresponding DC coefficient groups corresponding to one macroblock.

In step S213, DC coefficient average value calculation processing is performed. In the DC coefficient average value calculation process, first, the light quantity calculation unit 106 calculates an average value of four luminance DC coefficients (hereinafter referred to as luminance DC coefficient average value) among the six DC coefficients constituting the block corresponding DC coefficient group. calculate. The four luminance DC coefficients are DC coefficients respectively corresponding to the blocks Y0, Y1, Y2, and Y3 in FIG.

When the light quantity calculation unit 106 has acquired four sets of block-corresponding DC coefficient groups, an average value of four luminance DC coefficients (luminance DC coefficient average value) included in each block-corresponding DC coefficient group is calculated. The process is repeated four times. In the following, the four macroblocks corresponding to the four sets of block-corresponding DC coefficient groups are referred to as first, second, third and fourth macroblocks, respectively.

For example, the following arithmetic circuit 410 is used to calculate the average value of the luminance DC coefficient. In this case, the arithmetic circuit 410 is a circuit formed inside the light amount calculation unit 106.

FIG. 13 is a diagram showing an arithmetic circuit 410 as an example.

Referring to FIG. 13, the arithmetic circuit 410 includes a 4-input adder 411 and a 2-bit right shifter 412.

The 4-input adder 411 calculates a value obtained by adding four values (hereinafter referred to as an added value). Then, the 4-input adder 411 transmits the calculated addition value to the 2-bit right shifter 412.

The 2-bit right shifter 412 calculates a value obtained by dividing the received addition value by 4.

Here, it is assumed that four luminance DC coefficients are input to the four-input adder 411. In this case, the 4-input adder 411 calculates an addition value of the four luminance DC coefficients, and transmits the addition value to the 2-bit right shifter 412.

Then, the luminance DC coefficient average value is calculated by dividing the addition value received by the 2-bit right shifter 412 by 4.

According to the configuration of the arithmetic circuit 410, the calculated decimal fraction of the average value is rounded down. However, when rounding off the decimal fraction of the average value, a rounding incrementer is provided after the 2-bit right shifter 412. good.

By performing the above process for calculating the average luminance DC coefficient four times, the average luminance DC coefficient corresponding to each of the first, second, third, and fourth macroblocks is calculated.

If the light quantity calculation unit 106 has acquired only one set of block-corresponding DC coefficient groups, the DC coefficient average value calculation process in step S213 in FIG. 12 ends.

Referring to FIG. 12 again, in the DC coefficient average value calculation process, the light amount calculation unit 106 further determines the average value of the luminance DC coefficient average value in the first, second, third, and fourth macroblocks, the first value. The average value of the first color difference DC coefficient and the average value of the second color difference DC coefficient are calculated. As described above, the first color difference DC coefficient is a DC coefficient corresponding to the block Cb in FIG. The second color difference DC coefficient is a DC coefficient corresponding to the block Cr in FIG.

Specifically, the light quantity calculation unit 106 calculates the average value of the four luminance DC coefficient average values corresponding to the first, second, third, and fourth macroblocks calculated by the above processing (hereinafter, block luminance average). Value).

That is, the light quantity calculation unit 106 calculates the average luminance DC coefficient value using the four luminance DC coefficients corresponding to each macroblock. Further, the light quantity calculation unit 106 calculates a block luminance average value that is an average value of the luminance DC coefficient average values of the macroblocks using the luminance DC coefficient average values corresponding to the macroblocks. That is, the light quantity calculation unit 106 calculates the block luminance average value using the four luminance DC coefficients corresponding to each macroblock.

Further, the light quantity calculation unit 106 calculates an average value of the four first color difference DC coefficients corresponding to the first, second, third, and fourth macroblocks (hereinafter referred to as a block first color difference average value). Further, the light amount calculation unit 106 calculates an average value (hereinafter referred to as a block second color difference average value) of four second color difference DC coefficients respectively corresponding to the first, second, third, and fourth macroblocks.

That is, each of the block luminance average value, the block first color difference average value, and the block second color difference average value is calculated using a plurality of DC coefficients.

For the calculation of the block luminance average value, the block first color difference average value, and the block second color difference average value, for example, three arithmetic circuits 410 described above are used.

FIG. 14 is a diagram showing three arithmetic circuits 410.

Since the process of calculating the block luminance average value, the block first color difference average value, and the block second color difference average value is the same as the process of calculating the luminance DC coefficient average value described above, detailed description will not be repeated.

The calculated block luminance average value, block first color difference average value, and block second color difference average value are average values corresponding to the u-th dimming area.

In order to calculate the block luminance average value, the block first color difference average value, and the block second color difference average value, four arithmetic circuits 410 may be formed inside the light amount calculation unit 106.

Referring to FIG. 12 again, when the block luminance average value, the block first color difference average value, and the block second color difference average value are calculated, the DC coefficient average value calculation process ends.

In step S214, the light amount control unit 106 performs light amount control RGB value calculation processing for calculating the light amount control RGB value. The light amount control RGB value is an RGB value for controlling the light amount of the LED module corresponding to the u-th dimming region.

The light quantity control RGB value is composed of a light quantity control R value, a light quantity control G value, and a light quantity control B value.

The light quantity control R value, the light quantity control G value, and the light quantity control B value are described above using the block luminance average value (Y), the block first color difference average value (Cb), and the block second color difference average value (Cr). It is calculated by Equation 1 of YCbCr-RGB color conversion. Since the calculation method is well known, detailed description will not be repeated.

In step S215, the light amount calculation unit 106 transmits the calculated light amount control RGB value to the LED driver IC 110.

In step S216, the LED driver IC 110 controls the light amount of the LED module corresponding to the u-th dimming region corresponding to the received light amount control RGB value.

Specifically, the LED driver IC 110 supplies a current corresponding to the light amount control R value to the red LED of the LED module corresponding to the u-th dimming region. For example, the LED driver IC 110 supplies more current to the red LED as the light amount control R value is larger. That is, the larger the light quantity control R value, the larger the light quantity emitted by the red LED.

The LED driver IC 110 may supply more current to the red LED as the light amount control R value is smaller, for example.

Further, the LED driver IC 110 supplies a current corresponding to the light amount control G value to each of the two green LEDs of the LED module corresponding to the u-th dimming region. For example, the LED driver IC 110 supplies more current to each green LED as the light amount control G value is larger. That is, the larger the light quantity control G value, the larger the light quantity emitted by the green LED.

The LED driver IC 110 may supply more current to each green LED as the light amount control G value is smaller.

Further, the LED driver IC 110 supplies a current corresponding to the light amount control B value to the blue LED of the LED module corresponding to the u-th dimming region. For example, the LED driver IC 110 supplies more current to the blue LED as the light amount control B value is larger. That is, the larger the light quantity control B value, the larger the light quantity emitted by the blue LED.

Note that the LED driver IC 110 may supply more current to the blue LED as the light amount control B value is smaller, for example, without being limited to the above processing.

By this processing, the red LED, the two green LEDs, and the blue LED constituting the LED module emit light. That is, the LED module emits light of a light amount corresponding to the light amount control RGB value.

That is, the LED driver IC 110 controls the light amount of the LED module corresponding to the macroblock corresponding to the light amount control RGB value according to the light amount control RGB value. That is, the LED driver IC 110 uses the light amount control RGB value to control the light amount of the LED module corresponding to the macroblock corresponding to the light amount control RGB value.

The light amount control RGB value is a value calculated from the block luminance average value (Y), the block first color difference average value (Cb), and the block second color difference average value (Cr) as DC coefficients.

That is, the LED driver IC 110 corresponds to the macroblock corresponding to the light control RGB value according to the light control RGB value calculated using the block luminance average value, the first color difference average value, and the second color difference average value. The light quantity of the LED module to be controlled is controlled. A macro block is a block to be subjected to orthogonal transformation.

Therefore, the LED module emits light based on the block luminance average value (Y), the block first color difference average value (Cb), and the block second color difference average value (Cr). In other words, the LED driver IC 110 uses the block luminance average value (Y), the block first color difference average value (Cb), and the block second color difference average value (Cr) to obtain the LED module. Control the amount of light.

Here, each of the block luminance average value, the first color difference average value, and the second color difference average value is an average value of a plurality of DC coefficients. That is, each of the block luminance average value, the first color difference average value, and the second color difference average value is a value calculated using a plurality of DC coefficients.

That is, the LED driver IC 110 uses a value (light quantity control RGB value) obtained from an average value (for example, block luminance average value) of DC coefficients calculated using k (integer of 1 or more) DC coefficients. Thus, the light quantity of the LED module corresponding to the macro block corresponding to the average value of the DC coefficient is controlled.

In other words, the LED driver IC 110 uses the value (light quantity control RGB value) obtained from the k DC coefficients corresponding to the macroblock to be orthogonally transformed, and the LED corresponding to the macroblock corresponding to the k DC coefficients. Control the light intensity of the module. The DC coefficient is a DCT coefficient of a direct current component.

That is, the LED driver IC 110 uses the value obtained from the k DC coefficients, and among the plurality of LED modules included in the LED backlight module 112, the LED module corresponding to the macroblock corresponding to the k DC coefficients. Control the amount of light.

The LED driver IC 110 also performs image brightness adjustment on the LED module.

In step S217, the light amount calculation unit 106 determines whether or not all block-corresponding DC coefficient groups corresponding to one frame image (for example, full HD video) have been acquired. For example, when the number of light control areas is 2025, the light amount calculation unit 106 determines whether 2025 block-corresponding DC coefficient groups have been acquired. Each block-corresponding DC coefficient group includes six DC coefficients (four luminance DC coefficients, a first color difference DC coefficient, and a second color difference DC coefficient).

If YES in step S217, the backlight control process ends. On the other hand, if NO at step S217, the process proceeds to step S218.

In step S218, the light amount calculation unit 106 increments the value of u by 1.

Then, the process of step S211 is performed again.

Until the determination in step S217 is YES, the processes in steps S211 to S216 and S218 are repeated by the number of dimming areas, thereby p LEDs corresponding to p dimming areas corresponding to one frame, respectively. The light quantity of the module can be controlled.

For example, when the LCD panel 113 displays an image of 30 frames per second, the backlight control process is repeated every 1/30 seconds. Thereby, the light quantity of the p LED modules included in the LED backlight module 112 can be controlled.

In addition, video display processing and audio output processing are performed in synchronization with the control of the LED module. That is, a video and audio synchronization process called lip sync is performed. That is, the video stream decoding process and the audio stream decoding process are performed in parallel.

In the video display process, the LCD driver IC 111 performs control for causing the LCD panel 113 to display a video based on the video signal received from the video output processing unit 105.

Specifically, the LCD driver IC 111 drives each pixel of the LCD panel 113 while scanning based on the video signal received from the video output processing unit 105, and also double speed driving, display timing control, contrast adjustment, AD conversion. Also do.

In the audio output process, the audio output processing unit 108 performs control to output audio based on the audio signal received from the audio decoder 107 from the stereo speaker 114.

The synchronization of the above processes (LED module control, video display process, audio output process) and the like is performed by the CPU 115 controlling each unit in the display device 1000 based on the system control program. As a result, the AV playback timing is synchronized.

As described above, according to the present embodiment, p LEDs included in the LED backlight module 112 using the light amount control RGB value calculated from the block-corresponding DC coefficient group corresponding to each macroblock. Control the light intensity of the module. Six DC coefficients constituting each block corresponding DC coefficient group are obtained when the video stream is decoded. As a result, the amount of computation required to control each LED module can be greatly reduced.

That is, by using the DC coefficient obtained at the time of decoding the video stream, it is possible to efficiently reduce the calculation amount necessary for controlling the LED backlight module 112.

Therefore, the scale of an arithmetic circuit (drive circuit) that performs arithmetic operations necessary for controlling the LED backlight module 112 can be significantly reduced. As a result, the power consumption of the drive circuit of the LED backlight module 112 can be reduced. In addition, by reducing the cost of the backlight driving circuit, a digital television provided with an LED backlight can be realized at a low price.

It should be noted that each LED module may be controlled by using an average value of pixel values of a plurality of pixels constituting an image in a block corresponding to each dimming area. However, in this method, it is necessary to calculate an average value in the RGB color space.

However, in the present embodiment, by calculating the average value in the YCbCr space, the scale of the arithmetic circuit related to the color difference whose information amount is 1/4 of the luminance can be reduced to 1/4 compared with the above method. .

In the present embodiment, in a display device that displays video (moving image) encoded in units of blocks, each dimming is performed from a video stream using the characteristics of the compressed data structure in encoding based on the MPEG-2 standard. Information for controlling the LED module corresponding to the region can be accurately acquired. The display device is, for example, a liquid crystal digital television.

The average pixel value of the block can be taken out as the DC coefficient of the block subjected to DCT conversion. Therefore, in the present embodiment, a signal for driving each LED module is generated from the luminance Y and the DC coefficients of the color differences Cb and Cr.

Also, if the dimming area serving as the control unit of the backlight is set to an integral multiple of the block, the control value of the corresponding dimming area can be easily obtained as the average value of the DC coefficient of each block.

<Modification of the first embodiment>
In the modification of the first embodiment, only the configuration of the LED module is different from that of the first embodiment. That is, only the configuration of the p LED modules included in the LED backlight module 112 of FIG. 1 is different.

In the modification of the first embodiment, each LED module included in the LED backlight module 112 includes only an LED that emits white light (hereinafter, referred to as a white LED).

The display device in the modification of the first embodiment is the display device 1000 in FIG.

Also in the modification of the present embodiment, a video stream decoding process and an audio stream decoding process are performed as in the first embodiment.

Also, as in the first embodiment, the DC coefficient group acquisition process of FIG. 11 is performed.

Thus, every time the inverse quantization unit 203 performs inverse quantization in units of macroblocks, the block corresponding DC coefficient group is received.

In the modification of the present embodiment, a backlight control process A is performed instead of the backlight control process of FIG. In the modification of the present embodiment, processes other than the backlight control process A are performed in the same manner as in the first embodiment.

FIG. 15 is a flowchart of the backlight control process A. In FIG. 15, the process with the same step number as that of FIG. 12 is the same as the process described in the first embodiment, and therefore detailed description will not be repeated.

In step S213A, DC coefficient average value calculation processing A is performed. The DC coefficient average value calculation process A is different from the DC coefficient average value calculation process in step S213 of FIG. 12 in that the block first color difference average value and the block second color difference average value are not calculated. Other than that, since it is the same as the DC coefficient average value calculation processing, detailed description will not be repeated.

That is, in the DC coefficient average value calculation process A, only the block luminance average value is calculated.

Then, the process of step S215A is performed.

In step S215A, the light amount calculation unit 106 transmits the calculated block luminance average value to the LED driver IC 110.

In step S216A, the LED driver IC 110 controls the light amount of the LED module corresponding to the u-th dimming area corresponding to the received block luminance average value.

Specifically, the LED driver IC 110 supplies a current corresponding to the block luminance average value to the white LED of the LED module corresponding to the u-th dimming region. For example, the LED driver IC 110 supplies more current to the white LED as the block luminance average value increases. That is, the larger the block luminance average value, the greater the amount of light emitted by the white LED.

The LED driver IC 110 may supply more current to the white LED as the block luminance average value is smaller.

This process causes the white LEDs constituting the LED module to emit light. That is, the LED module emits light having a light amount corresponding to the block luminance average value.

That is, the LED driver IC 110 controls the light amount of the LED module using the block luminance average value as a DC coefficient. The block luminance average value is a value calculated using a plurality of DC coefficients.

That is, the LED driver IC 110 uses a DC coefficient average value (block luminance average value) calculated using k (integer of 1 or more) DC coefficients, and a macro corresponding to the DC coefficient average value. The light quantity of the LED module corresponding to the block is controlled.

That is, the LED driver IC 110 uses a value (block luminance average value) obtained from the k DC coefficients, and among the plurality of LED modules included in the LED backlight module 112, the macro corresponding to the k DC coefficients. The light quantity of the LED module corresponding to the block is controlled.

In step S217, the same processing as that of the first embodiment is performed, and thus detailed description will not be repeated.

For example, when the LCD panel 113 displays an image of 30 frames per second, the backlight control process A is repeated every 1/30 seconds. Thereby, the light quantity of the p LED modules included in the LED backlight module 112 can be controlled.

As described above, according to the modification of the present embodiment, it is not necessary to calculate the block first color difference average value and the block second color difference average value, and it is not necessary to calculate the light amount control RGB value. Therefore, in the modified example of the present embodiment, the amount of calculation required for controlling the p LED modules included in the LED backlight module 112 can be further reduced as compared with the first embodiment.

As a result, the scale of the arithmetic circuit for calculating the value for controlling the light quantity of the LED module can be made smaller than that of the first embodiment.

As a matter of course, according to the modification of the present embodiment, as in the first embodiment, the control of the LED backlight module 112 is performed by using the DC coefficient obtained when the video stream is decoded. There is also an effect that it is possible to efficiently reduce the amount of calculation required for.

Note that the LED backlight control device 500 in the first embodiment and the modified example of the first embodiment is incorporated in a liquid crystal digital TV as shown in FIG. 16, for example. That is, FIG. 16 is an external view of the display device 1000 according to the first embodiment and a modification of the first embodiment.

(Function block diagram)
FIG. 17 is a block diagram showing a characteristic functional configuration of the LED backlight control device 2000. The LED backlight control device 2000 corresponds to either the LED backlight control device 500 or the display device 1000. The LED backlight control device 2000 is also an LED backlight control module.

That is, FIG. 17 is a block diagram showing main functions related to the present invention among the functions of either the LED backlight control device 500 or the display device 1000.

The LED backlight control device 2000 controls the LED backlight. The LED backlight is used for video display. The LED backlight includes a plurality of LED modules using LEDs.

Functionally, the LED backlight control device 2000 includes an acquisition unit 510 and a light amount control unit 520.

The obtaining unit 510 obtains k (integer of 1 or more) DC coefficients that are DCT coefficients of the DC component corresponding to the block to be orthogonally transformed from the encoded data. The encoded data is data generated by performing an encoding process involving orthogonal transformation on a video in units of blocks.

The acquisition unit 510 corresponds to, for example, the video decoder 104 including the inverse quantization unit 203 that performs the process of step S111 in FIG. 11 or the light amount calculation unit 106 in step S211 of FIG.

The light quantity control unit 520 uses a value obtained from the k DC coefficients acquired by the acquisition unit 510, and among the plurality of LED modules included in the LED backlight module 112, a block corresponding to k DC coefficients. The light quantity of the LED module corresponding to is controlled.

The light quantity control unit 520 corresponds to, for example, the LED driver IC 110 that performs the process of step S216.

Note that all or part of the acquisition unit 510 and the light amount control unit 520 included in the LED backlight control device 2000 of FIG. 17 may be configured by hardware such as an LSI (Large Scale Integration). Good. In addition, all or part of the acquisition unit 510 and the light amount control unit 520 may be a program module executed by a processor such as a CPU.

As described above, the LED backlight control device 500 or the display device 1000 according to the present invention has been described based on the embodiments. However, the present invention is not limited to these embodiments. Unless it deviates from the meaning of this invention, the form which carried out various deformation | transformation which those skilled in the art can think to this embodiment, or the structure constructed | assembled combining the component in different embodiment is also contained in the scope of the present invention. .

Further, all or some of the plurality of components constituting the LED backlight control device 500 may be configured by hardware. For example, all or some of the plurality of components constituting the LED backlight control device 500 may be configured by one system LSI (Large Scale Integration).

In addition, each process described in the first embodiment and the modification of the first embodiment may be realized by software. Then, this software may be distributed by software download or the like. Further, this software may be recorded on a recording medium such as a CD-ROM and distributed. This also applies to other embodiments in this specification.

For example, the CPU 115 may execute each process performed by the video decoder 104 and each process performed by the light amount calculation unit 106 by software.

Further, the present invention may be realized as an LED backlight control method in which the operation of the characteristic components included in the LED backlight control device 500 is a step. Moreover, you may implement | achieve as a program which makes a computer perform the step contained in such a reproduction | regeneration method. Further, the present invention may be realized as a computer-readable recording medium that stores such a program. Such a program may be distributed via a transmission medium such as the Internet.

In the first embodiment and the modification of the first embodiment, the LED backlight control device 500 of the present invention is exemplified as one component incorporated in a liquid crystal digital TV as a display device. However, the present invention is not limited to this. The LED backlight control device 500 may be mounted on other video display products such as a portable DVD player.

Note that the video signal output from the video output processing unit 105 and the video signal output from the video decoder 104 may be different. For this reason, it may be necessary to separately deal with LED backlight control.

For example, when the output video of the video decoder 104 is reduced and displayed as a thumbnail in the rectangular area and the graphics information is displayed in another area, the backlight of the graphics area must be controlled based on the graphics video information.

In this case, a process that invalidates the control of the backlight in the graphics area, specifically, a control method for fixing the LED backlight in the graphics area to a certain brightness is considered as one of the options.

For example, when displaying character information superimposed on video information decoded by the video decoder 104, a control method of disabling dimming control of the character display area and fixing the area to a constant light amount is considered as one of the options. It is done.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

The present invention can be used as an LED backlight control device that can efficiently reduce the amount of calculation required for controlling the LED backlight.

Also, the LED backlight control device according to the present invention is incorporated in a liquid crystal digital TV, a mobile phone, a car navigation system, a portable DVD player, etc. as a circuit for controlling local light control of the LED backlight.

104 Video decoder 105 Video output processing unit 106 Light amount calculation unit 109 LCD display control unit 110 LED driver IC
111 LCD driver IC
112 LED backlight module 113 LCD panel 203 Inverse quantization unit 410 Arithmetic circuit 500, 2000 LED backlight control device 510 Acquisition unit 520 Light amount control unit 1000 Display device

Claims (8)

1. An LED (Light Emitting Diode) backlight used to display an image, and an LED backlight control device that controls an LED backlight including a plurality of LED modules using LEDs,
   It is a DCT (Discrete Cosine Transform) coefficient of a direct current component corresponding to the block to be subjected to the orthogonal transformation from the coded data generated by performing the encoding process with the orthogonal transformation on a block basis. An acquisition unit for acquiring k (integer of 1 or more) DC coefficients;
   A light amount for controlling a light amount of an LED module corresponding to a block corresponding to the k DC coefficients among the plurality of LED modules, using a value obtained from the k DC coefficients obtained by the obtaining unit. An LED backlight control device comprising: a control unit.
2. k is an integer greater than or equal to 2,
   The LED backlight control device further includes:
   A calculation unit that calculates a DC coefficient average value that is an average value of the k DC coefficients;
   The light quantity control unit uses the DC coefficient average value calculated using the k DC coefficients or a value obtained from the DC coefficient average value to a block corresponding to the DC coefficient average value. The LED backlight control device according to claim 1, wherein the light amount of the corresponding LED module is controlled.
3. An LED backlight used for displaying an image, and an LED backlight control method performed by an LED backlight control device that controls an LED backlight including a plurality of LED modules using LEDs,
   A DC coefficient, which is a DCT coefficient of a DC component corresponding to the block to be subjected to the orthogonal transformation, is obtained from coding data generated by performing an encoding process involving the orthogonal transformation on the video in units of blocks. An acquisition step of acquiring an integer of 1 or more,
   A light amount for controlling the light amount of the LED module corresponding to the block corresponding to the k DC coefficients among the plurality of LED modules, using the value obtained from the k DC coefficients obtained in the obtaining step. An LED backlight control method comprising: a control step.
4. k is an integer greater than or equal to 2,
   The LED backlight control method further includes:
   A calculation step of calculating a DC coefficient average value that is an average value of the k DC coefficients;
   In the light amount control step, a block corresponding to the DC coefficient average value is calculated using the DC coefficient average value calculated using the k DC coefficients or a value obtained from the DC coefficient average value. The LED backlight control method according to claim 3, wherein the light quantity of the corresponding LED module is controlled.
5. An LED backlight used for displaying an image, and an LED backlight control module for controlling an LED backlight including a plurality of LED modules using LEDs,
   A DC coefficient, which is a DCT coefficient of a DC component corresponding to the block to be subjected to the orthogonal transformation, is obtained from coding data generated by performing an encoding process involving the orthogonal transformation on the video in units of blocks. An integer greater than or equal to 1)
   A light amount for controlling the light amount of the LED module corresponding to the block corresponding to the k DC coefficients among the plurality of LED modules, using a value obtained from the k DC coefficients obtained by the obtaining unit. With control
   LED backlight control module comprising:
6. k is an integer greater than or equal to 2,
   The LED backlight control module further includes:
   A calculation unit that calculates a DC coefficient average value that is an average value of the k DC coefficients;
   The light quantity control unit uses the DC coefficient average value calculated using the k DC coefficients or a value obtained from the DC coefficient average value to a block corresponding to the DC coefficient average value. The LED backlight control module according to claim 5, wherein the light quantity of the corresponding LED module is controlled.
7. An LED backlight used for displaying an image, and a display device for controlling an LED backlight including a plurality of LED modules using LEDs,
   A DC coefficient, which is a DCT coefficient of a DC component corresponding to the block to be subjected to the orthogonal transformation, is obtained from coding data generated by performing an encoding process involving the orthogonal transformation on the video in units of blocks. (An integer greater than or equal to 1)
   A light amount for controlling a light amount of an LED module corresponding to a block corresponding to the k DC coefficients among the plurality of LED modules, using a value obtained from the k DC coefficients obtained by the obtaining unit. A display device comprising: a control unit.
8. k is an integer greater than or equal to 2,
   The display device further includes:
   A calculation unit that calculates a DC coefficient average value that is an average value of the k DC coefficients;
   The display device corresponds to a block corresponding to the DC coefficient average value using the DC coefficient average value calculated using the k DC coefficients or a value obtained from the DC coefficient average value. The display device according to claim 7, wherein the light amount of the LED module to be controlled is controlled.
   

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