JP2010097102A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display properly correcting non-uniform brightness, according an image displayed in a display area. <P>SOLUTION: The liquid crystal display 100 is constituted so that a determination program 125f decides whether to correct an image data by a correction program 125b, based on whether the image data output to the liquid crystal display 100 satisfies a preset condition or not. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device.

In recent years, a liquid crystal display device that irradiates backlight light from the back side of a liquid crystal panel and displays an image on the liquid crystal panel has become widespread.
For example, an LED (Light Emitting Diode) is used as the light source of the backlight light. However, luminance and color development may vary depending on the performance difference (individual difference) of each LED and aging. In such a case, the brightness on the display screen varies depending on the location, and uneven brightness occurs on the display screen.

Therefore, as a means for correcting the brightness unevenness as described above, for example, an input of an image signal is received, and gradation values of pixels included in each screen area obtained by dividing the display screen of the display unit into a plurality of areas are determined. Based on the gradation value, the luminance value for each screen area, and a predetermined correction coefficient, the corrected gradation value for each screen area is calculated, and the display image based on the gradation value is displayed for each screen area. Is known (for example, see Patent Document 1).
In addition, when correcting brightness unevenness, there is a method for executing the above-described correction when conditions (conditions specified by a file name, application name, function name, etc.) preset by the user are satisfied. It is known (see, for example, Patent Document 2).
JP 2006-184305 A JP 2008-58506 A

However, when the brightness unevenness correction as in the invention described in Patent Document 1 is performed, the correction is made so that the gradation value is lowered over the entire screen area by the amount of the brightness unevenness. On the other hand, the display screen becomes darker than before correction. Therefore, for example, even when an image displayed on the display screen is relatively inconspicuous, such as a moving image, the above correction is automatically performed every time the image is displayed on the display screen. Therefore, there is a problem that it is difficult to identify the image. In addition, there is a problem in that the execution of the correction process causes a delay in displaying an image such as a moving image.
On the other hand, in the invention described in Patent Document 2, correction is not made unless the conditions set in advance by the user are satisfied, but the conditions require prior setting based on the file name, application name, function name, and the like. Therefore, it is not determined whether or not brightness unevenness should be corrected for an image displayed on the display screen from time to time. Therefore, the invention described in Patent Document 2 may have the same problem as the invention described in Patent Document 1.

  An object of the present invention is to provide a liquid crystal display device that can suitably correct brightness unevenness in accordance with an image displayed in a display area.

In order to solve the above-mentioned problem, the invention described in claim 1
A liquid crystal panel in which a display area for displaying an image based on image data is divided into a plurality of sub-display areas, a backlight composed of a plurality of light sources arranged corresponding to each of the sub-display areas, and luminance for each of the light sources Based on the brightness adjustment data stored by the storage means, the storage means for storing the brightness adjustment data related to the dispersion of the light, and the variation of the brightness of the light output from the light source and passing through the liquid crystal panel is eliminated. And a correction means for correcting the image data,
Determining means for determining whether to perform correction by the correcting means depending on whether the image data satisfies a preset condition;
The correction unit performs the correction when the determination unit determines to perform the correction.

  According to a second aspect of the present invention, in the liquid crystal display device according to the first aspect of the present invention, the liquid crystal display device further includes a still image determination unit that determines whether an image based on the image data is a still image, and the determination unit includes the still image When the image determination unit determines that the image is a still image, the correction unit determines to perform the correction.

  According to a third aspect of the present invention, in the liquid crystal display device according to the first aspect, the ratio calculating means for calculating the ratio of the same color used in the image based on the image data to the entire image, and the ratio calculating means Ratio determining means for determining whether or not the calculated ratio exceeds a predetermined value, and the determining means determines the correction when the ratio determining means determines that the ratio exceeds a predetermined value. It is determined that the correction is performed by means.

  According to a fourth aspect of the present invention, in the liquid crystal display device according to the first aspect, the change amount calculating means for comparing the image data between frames and calculating the change amount of the image data, and the change amount calculating means. Change amount determining means for determining whether or not the changed amount is less than a predetermined value, and the determining means, when the change amount determining means determines that the change amount is less than a predetermined value, It is determined that the correction is performed by the correction unit.

  According to a fifth aspect of the present invention, there is provided a liquid crystal panel in which a display area for displaying an image based on image data is divided into a plurality of sub display areas, and arranged corresponding to each of the sub display areas to emit light with a predetermined luminance. A backlight composed of a plurality of LED light sources, storage means for storing brightness adjustment data relating to brightness variation for each LED light source, and output from the LED light source based on the brightness adjustment data stored by the storage means In a liquid crystal display device comprising correction means for correcting image data so as to eliminate variations in the luminance of light passing through the liquid crystal panel between the LED light sources, whether the image data satisfies a preset condition Determining means for determining whether to perform correction by the correcting means, and whether the image based on the image data is an OSD image An OSD image determination unit that determines whether the correction is performed by the correction unit when the OSD image determination unit determines that the image is an OSD image. Features.

According to the present invention, it is possible to determine whether or not to correct the image data by the correction unit depending on whether or not the image data of the image displayed in the display area satisfies a preset condition. It is configured.
In other words, according to the present invention, the image based on the image data displayed in the display area is, for example, an image in which uneven brightness is not noticeable, such as a moving image, and is corrected when the uneven brightness need not be corrected. On the contrary, it is an image that is conspicuous in uneven brightness, such as a still image, and when it is necessary to correct uneven brightness, it is determined that correction should be performed. Whether or not to execute correction can be determined for each image displayed on the screen.
Therefore, it can be said that the present invention is a liquid crystal display device capable of suitably correcting the brightness unevenness according to the image displayed in the display area.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The scope of the invention is not limited to the illustrated example.
FIG. 1 is a block diagram showing a main configuration of the liquid crystal display device of the present embodiment. 2A is a diagram for explaining a sub display area S that constitutes the display area of the liquid crystal panel 5 of the present embodiment, and FIG. 2B shows the backlight 8 of the present embodiment. It is a figure for demonstrating the light source L to comprise.

  As shown in FIG. 1, for example, the liquid crystal display device 100 according to the present embodiment includes a signal input unit 1, a video processing unit 2, a timing control unit 3, a frame memory 4, a liquid crystal panel 5, a scanning line driving unit 6, and signal lines. A drive unit 7, a backlight 8, a backlight control unit 9, a selection operation unit 10, a control unit 12, and the like are provided.

  The signal input unit 1 includes, for example, an antenna and tuner that receives a television broadcast signal, various video terminals that receive an image signal from an external device, and the like, and receives an input image signal (image data). And output to the video processing unit 2.

The video processing unit 2 includes an A / D conversion circuit, an RGB generation circuit, an image quality adjustment circuit, and the like, generates an RGB digital image signal based on the image signal supplied from the signal input unit 1, A scaling process corresponding to the number of pixels of the panel 5 is performed to generate an image signal for one frame. Further, the image memory for one frame is subjected to various image quality adjustments such as brightness, contrast, color density, hue, and sharpness based on the image quality adjustment signal output from the control unit 12, and then the frame memory. 4 is output.
In addition, when correction data stored in the correction data storage unit 123 is input through execution of a correction program 125b described later, the video processing unit 2 performs RGB value change processing on the generated image via the image quality adjustment circuit. Therefore, it is possible to output an image without uneven brightness.

  The timing control unit 3 generates a timing signal indicating one line period and a timing signal indicating one frame period based on the image signal supplied from the signal input unit 1, and supplies the timing signal to each unit of the liquid crystal display device 100. To do.

  The frame memory 4 accumulates image signals input from the video processing unit 2 in units of frames and outputs the image signals to a liquid crystal display (not shown).

The liquid crystal panel 5 is formed by sealing liquid crystal between a pair of substrates disposed at a predetermined interval. The pair of substrates is sandwiched between two polarizing plates whose polarization axes are orthogonal to each other, and a backlight 8 is disposed on the back side. The liquid crystal panel 5 is divided into a plurality of sub-display areas S that are equally divided into a matrix of n vertical x m horizontal, as shown in FIG. (1, 1) to S (m, n).
On the top surface of the substrate, p rows of scanning lines X (X _{1 to} X _p ) and q columns of signal lines Y (Y _{1 to} Y _q ) are arranged so as to be orthogonal to each other. The liquid crystal panel 5 employs, for example, an active matrix driving method, and a thin film transistor (TFT) as an active element is disposed at each intersection pixel of the scanning line X and the signal line Y. . A pixel electrode is formed in each pixel, and a counter electrode is formed on the opposing substrate so as to face the pixel electrode. An alignment film is formed on the opposing surfaces of the pixel electrode and the counter electrode.

The scanning line driving unit 6 is provided corresponding to each of the scanning lines X (X _{1 to} X _p ) in the liquid crystal panel 5, and sequentially selects each scanning line X according to the timing signal from the timing control unit 3. Thus, the TFTs connected on the same scanning line X are turned on / off.
The signal line driving unit 7 is provided corresponding to each of the signal lines Y (Y _{1 to} Y _q ) in the liquid crystal panel 5, and in synchronization with scanning of each scanning line X by the scanning line driving unit 6, A voltage corresponding to the image signal input from the processing unit 2 is applied to the signal line Y.
When the scanning line X and the signal line Y are driven by the scanning line driving unit 6 and the signal line driving unit 7, the TFTs of the pixels at the intersections thereof are turned on and charges are accumulated in the pixel electrodes. The alignment direction of the liquid crystal sandwiched between the liquid crystal panel 5 and the counter electrode changes, and the light irradiated from the backlight 8 provided on the back side of the liquid crystal panel 5 passes through the alignment film and the polarizing plate in units of pixels. Or block it.

  The backlight 8 is a backlight composed of a plurality of light sources L corresponding to the sub display areas S of the liquid crystal panel 5. In addition, since each of the light sources L includes a plurality of LEDs arranged at predetermined positions on the substrate, the backlight 8 functions as an LED backlight.

Further, the sub display area S of the liquid crystal panel 5 and the light sources L of the backlight 8 are configured to correspond in a one-to-one correspondence.
Specifically, as shown in FIGS. 2A and 2B, the display area of the liquid crystal panel 5 is sub-display areas S (1, 1) to S (m, n) of n vertical × m horizontal. When the backlight 8 is equally divided into a matrix, the backlight 8 has a one-to-one correspondence with n sub-display areas S (1,1) to S (m, n) in the liquid crystal panel 5 in the vertical n × horizontal m. It is comprised from the light source L (1, 1)-L (m, n) of the vertical n x horizontal m.
For example, when the liquid crystal panel 5 is composed of pixels of 768 rows (p rows) × 1024 columns (q columns), if the display region is divided with a region including pixels of 64 rows × 64 columns as one sub display region S The entire display area of the liquid crystal panel 5 is composed of vertical (n) × 16 (m) sub display areas S. At this time, the backlight 8 is similarly composed of light sources L of vertical 12 (n) × horizontal 16 (m).

  In accordance with an instruction from the control unit 12, the backlight control unit 9 causes only the LED instructed from the control unit 12 to emit light among the plurality of LEDs provided in each light source L constituting the LED backlight 9.

  The selection operation unit 10 includes various buttons / switches such as a switch for switching on / off the power of the liquid crystal display device 100 and a button for switching an output state of image data such as television broadcasting and video input. The user can execute a predetermined selection or determination by the user's operation.

  The control unit 12 includes, for example, a CPU (Central Processing Unit) 121, a RAM (Random Access Memory) 122 used as a work area of the CPU 121, and correction data storage composed of an EEPROM (Electrically Erasable Programmable ROM) capable of rewriting and erasing data. And a ROM 125 (Read Only Memory) for storing various programs executed by the CPU 121.

  The CPU 121 executes various programs stored in the ROM 125 in accordance with input signals input from each unit of the liquid crystal display device 100, and outputs an output signal to each unit based on the execution program. Overall control of the operation of the apparatus 100 is performed.

  The RAM 122 includes, for example, a program storage area for expanding a processing program executed by the CPU 121, a data storage area for storing a processing result generated when the input data and the processing program are executed, and the like.

The correction data storage unit 123 (storage means) stores correction data (luminance adjustment data) for correcting image brightness unevenness based on image data, which is used by executing a correction program 125b described later.
Specifically, the correction data specifies, for example, the sub display area S indicating the lowest maximum brightness from the highest brightness for each light source L corresponding to the sub display area S measured in advance, and is displayed on the liquid crystal display device 100. The image that requires the highest luminance among the images to be displayed is displayed at the highest luminance of the specified sub display area S over the entire display area (that is, the luminance of light between the sub display areas S). This is data for performing correction (to eliminate variation).
That is, the difference between the luminance of each of the sub display areas S (1, 1) to S (m, n) and the luminance of the specified sub display area S (for example, the sub display area S showing the lowest maximum luminance). And the difference amount is “20”, etc.), the difference between the pixels corresponding to the arrangement position of each sub display area S of the image is determined. This is data relating to the amount of change in RGB value for reducing the luminance by an amount.

  The ROM 125 includes, for example, a correction program 125b, an image determination program 125c, a ratio calculation program 125d, a ratio determination program 125e, a determination program 125f, and the like in the program storage area.

The correction program 125b is a program that causes the CPU 121 to realize a function of correcting image data to be displayed on the liquid crystal display device 100 based on the correction data stored in the correction data storage unit 123, for example.
Specifically, when the CPU 121 executes the correction program 125b, the correction data stored in the correction data storage unit 123 is output to the video processing unit 2, and the RGB value changing process is executed on the output image data. Thus, the image data can be corrected.
The CPU 121 functions as a correction unit by executing the correction program 125b.

The image determination program 125c is a program for causing the CPU 121 to determine the type of image data input to the signal input unit 1, for example.
Specifically, when the CPU 121 executes the image determination program 125c, for example, two image data between successive frames in accordance with a moving picture standard such as MPEG (Moving Picture Expert Group) are input to the signal input unit 1. Then, since the change amount for each pixel between the two image data is input to the control unit 12, based on the change amount obtained by summing the change amount for each pixel for the entire image, the image is as follows. The type of
First, when the amount of change is equal to 0, there is no change in the two image data between successive frames, so that the image data is determined as a still image (for example, an OSD image or the like) in which uneven brightness is conspicuous.
Next, when the amount of change has a value other than 0, two image data between successive frames have changed, so that the image data is determined as a moving image. For a moving image, whether or not the amount of change is below a predetermined value (for example, a value of about 5% of the sum of the pixel values of the image data), that is, a change in two image data between one frame. It is determined whether or not the image is relatively moving and is a moving image that is close to a still image and easily noticeable brightness unevenness.
Therefore, the CPU 121 functions as a still image determination unit, a change amount calculation unit, a change amount determination unit, and an OSD image determination unit by executing the image determination program 125c.

The ratio calculation program 125d is a program that, for example, causes the CPU 121 to realize a function of calculating a ratio of the entire image of the same color used for an image based on the image data input to the signal input unit 1.
Specifically, when the CPU 121 executes the ratio calculation program 125d, for example, the RGB value for each pixel of the image data input to the signal input unit 1 is acquired, and the number of pixels with matching RGB values is added. By dividing this by the total number of pixels and converting it as a percentage, the ratio of the entire image of the same color used in the image is calculated.
Therefore, the CPU 121 functions as a ratio calculation unit by executing the ratio calculation program 125d.

The ratio determination program 125e is a program that, for example, causes the CPU 121 to realize a function of determining whether the ratio calculated by the ratio calculation program 125d exceeds a predetermined value.
Specifically, when the CPU 121 executes the ratio determination program 125e, for example, the ratio of the entire image of the same color used for the image based on the image data exceeds a predetermined value (for example, about 30%). It is possible to determine whether or not the image is a conspicuous image with uneven brightness using the same color.
Therefore, the CPU 121 functions as a ratio determination unit by executing the ratio determination program 125e.

The determination program 125f determines, for example, whether or not to correct the image data by the correction program 125a depending on whether or not the image data output to the liquid crystal display device 1 satisfies a preset condition. It is a program that realizes the function.
Specifically, when the CPU 121 executes the determination program 125f, for example, when the image data input to the signal input unit 1 is determined to be a still image by the execution of the image determination program 125c, between successive frames. When it is determined that the amount of change in the image data is below a predetermined value, or when the ratio of the entire image of the same color used for the image exceeds the predetermined value by executing the ratio determination program 125e It can be determined that correction of image data is to be performed, and other image data can be determined not to be corrected.
Therefore, by executing the determination program 125f, a still image such as an OSD (On-Screen Display) image or a photographic image input from the outside to the liquid crystal display device 1, or a frame although it is a moving image. The correction is made only for images that are conspicuous in uneven brightness, such as moving images that are similar to still images or images that use the same color throughout the image. It is possible to prevent correction of an image that is less noticeable in brightness unevenness, such as a moving image with a large image change.
The CPU 121 functions as a determination unit by executing the determination program 125f.

  Next, the flow of correction processing performed in the liquid crystal display device 100 of the present embodiment will be described with reference to the flowchart of FIG.

First, a predetermined image signal (image data) is input to the signal input unit 1 of the liquid crystal display device 100 (step S1).
Next, the CPU 121 determines the type of the image data input in step S1 by executing the image determination program 125c (step S2).
Next, the CPU 121 executes the ratio calculation program 125d to calculate the ratio of the entire image of the same color used for the image based on the image data input in step S1 (step S3).
Further, the CPU 121 determines whether or not the ratio calculated in step S3 exceeds a predetermined value by executing the ratio determination program 125e (step S4).
Next, the CPU 121 determines whether or not to correct the image data by executing the determination program 125f (step S5).
Next, as a result of the determination in step S2, the CPU 121 executes the correction program 125b when the image data is a still image or when the change amount of the image data between one frame is less than a predetermined value (step S6; Yes). As a result, the image data is corrected (step S8).
On the other hand, as a result of the determination in step S2, the CPU 121 proceeds to the process of step S7 when the change amount of the image data between one frame is not less than the predetermined value (step S6; No).
Then, as a result of the determination in step S5, the CPU 121 executes the correction program 125b when the ratio of the entire image of the same color used for the image exceeds a predetermined value (step S7; Yes). Data correction is executed (step S8).
On the other hand, as a result of the determination in step S5, the CPU 121 does not perform correction of the image data when the ratio of the entire image of the same color used for the image does not exceed a predetermined value (step S8; No).
Thus, the process ends.

According to the liquid crystal display device 100 in the present embodiment described above, the correction of the image data by the correction program 125b is performed depending on whether or not the image data output to the liquid crystal display device 100 satisfies a preset condition. It can be determined by the determination program 125f.
That is, according to the present invention, the image based on the image data output to the liquid crystal display device 100 is, for example, an image in which uneven brightness is not noticeable, such as a moving image, and the uneven brightness need not be corrected. Is determined not to be corrected, and conversely, is an image in which unevenness in brightness such as a still image is conspicuous, and when it is necessary to correct unevenness in brightness, it is determined that correction is performed. In addition, it is possible to determine whether or not to execute correction for each image data output at that time.
Therefore, it can be said that the present invention is a liquid crystal display device capable of suitably correcting the brightness unevenness according to the image displayed in the display area.

Further, the image determination program 125c determines whether the image data input to the signal input unit 1 is a still image or not, and the change in two image data between successive frames is relatively gradual, and the brightness is close to a still image. It is determined whether or not the moving image is easily noticeable, and the determination program 125f determines whether the image data is a still image or the change amount of two image data between one frame is below a predetermined value. It can be determined that the image data is corrected.
That is, a still image such as an OSD (On-Screen Display) image or a photographic image input from the outside to the liquid crystal display device 1 or a moving image, but a change in image between frames is small, and a still image It is possible to determine to perform correction only for an image that is conspicuous in brightness unevenness, such as a moving image close to.

Further, the ratio calculation program 125d and the ratio determination program 125e determine whether the ratio of the entire image of the same color used for the image based on the image data output to the liquid crystal display device 100 exceeds a predetermined value. The determination program 125f can determine that the image data is to be corrected when the predetermined value is exceeded.
That is, it is possible to determine to perform correction only for an image in which uneven brightness is conspicuous, such as an image in which the same color is frequently used in the entire image.

The scope of the present invention is not limited to the above embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.
For example, the number of divisions and the division method of the sub display area S and the light source L are arbitrary, and the division may be made into at least two or more areas.
Further, the number and arrangement position of the LEDs provided in the light source L are not limited to the example of the above embodiment.
Furthermore, the preset conditions used in the determination program 125f are not limited to the above embodiment. For example, the determination program 125f causes the CPU 121 to realize a function of determining that the correction of the image data is performed by the correction program 125b when the user selects to correct the image data via the selection operation unit 10. Etc. That is, the necessity of correcting the image data can be determined each time according to the user's selection, so that the brightness unevenness can be corrected suitably for the user.

It is a block diagram which illustrates the principal part structure of the liquid crystal display device in this embodiment. (A) is a figure explaining the sub display area which comprises the display area of a liquid crystal panel, (B) is a figure explaining the light source provided corresponding to each sub display area. It is a flowchart which shows the flow of the correction process in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Liquid crystal display device 1 Signal input part 2 Image processing part 3 Timing control part 4 Frame memory 5 Liquid crystal panel 6 Scan line drive part 7 Signal line drive part 8 Backlight 10 Selection operation part 12 Control part 121 CPU (correction means, determination means) , Still image determination means, ratio calculation means, ratio determination means, change amount calculation means, change amount determination means, OSD image determination means)
123 Correction data storage unit (storage means)
125b Correction program (correction means)
125c Image determination program (still image determination means, change amount calculation means, change amount determination means, OSD image determination means)
125d ratio calculation program (ratio calculation means)
125e Ratio judgment program (ratio judgment means)
125f determination program (determination means)

Claims (5)

A liquid crystal panel in which a display area for displaying an image based on image data is divided into a plurality of sub-display areas, a backlight composed of a plurality of light sources arranged corresponding to each of the sub-display areas, and luminance for each of the light sources Based on the brightness adjustment data stored by the storage means, the storage means for storing the brightness adjustment data related to the dispersion of the light, and the variation of the brightness of the light output from the light source and passing through the liquid crystal panel is eliminated. And a correction means for correcting the image data,
Determining means for determining whether to perform correction by the correcting means depending on whether the image data satisfies a preset condition;
The liquid crystal display device, wherein the correction unit performs the correction when the determination unit determines to perform the correction. The liquid crystal display device according to claim 1.
Comprising still image judging means for judging whether an image based on the image data is a still image;
The determining means includes
A liquid crystal display device, wherein when the still image determining unit determines that the image is a still image, the correction unit determines to perform the correction. The liquid crystal display device according to claim 1.
A ratio calculating means for calculating a ratio of the same color used in the image based on the image data to the entire image;
Ratio determining means for determining whether or not the ratio calculated by the ratio calculating means exceeds a predetermined value,
The determining means includes
The liquid crystal display device according to claim 1, wherein when the ratio determining unit determines that the ratio exceeds a predetermined value, the correction unit determines to perform the correction. The liquid crystal display device according to claim 1.
A change amount calculating means for comparing image data between frames and calculating a change amount of the image data;
Change amount determination means for determining whether or not the change amount calculated by the change amount calculation means is less than a predetermined value;
The determining means includes
The liquid crystal display device according to claim 1, wherein when the change amount determining unit determines that the change amount is less than a predetermined value, the correction unit determines to perform the correction. A liquid crystal panel in which a display area for displaying an image based on image data is divided into a plurality of sub display areas, and a backlight composed of a plurality of LED light sources arranged corresponding to each of the sub display areas and emitting light with a predetermined luminance , Storage means for storing brightness adjustment data relating to brightness variation for each LED light source, and brightness of light output from the LED light source and passed through the liquid crystal panel based on the brightness adjustment data stored by the storage means In a liquid crystal display device comprising correction means for correcting image data so as to eliminate variation between the LED light sources,
Determining means for determining whether or not to perform correction by the correcting means depending on whether or not the image data satisfies a preset condition;
OSD image determination means for determining whether an image based on the image data is an OSD image,
The determining means includes
A liquid crystal display device, wherein when the OSD image determination unit determines that the image is an OSD image, the correction unit determines to perform the correction.

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