JP2008042843A - Correction of luminance unevenness of screen of liquid crystal panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein conventional techniques for solving unevenness luminance on the screen of a liquid crystal panel is high in cost. <P>SOLUTION: A luminance correction system is provided for correcting luminance unevenness on the screen of a liquid crystal panel, comprising a direct backlight unit in which a plurality of fluorescent tubes are juxtaposed at predetermined intervals on the back side. The luminance correction system comprises an image display means for displaying a predetermined test image on the screen; a luminance measuring means for measuring the luminance of the screen, on which the test image is displayed for each region on the screen; a correction data generating means which inputs the measured luminance of each region of the screen and generates correction data for reducing the luminance unevenness of the regions for each region, according to the luminance of each of the regions; and a luminance correcting means for correcting the luminance of image data, representing an arbitrary image to be displayed on the liquid crystal panel, for each region based on the correction data. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to correction of luminance unevenness on a screen of a liquid crystal panel.

  When displaying images using a liquid crystal panel equipped with a direct backlight unit in which a plurality of fluorescent tubes are arranged at a predetermined interval on the back side, uneven brightness of the screen caused by the arrangement of the fluorescent tubes is a problem. It was. In other words, since the fluorescent tube does not cover the entire back surface of the panel, there is a difference in the brightness of the screen between the region where the fluorescent tube is arranged directly behind and the region where it is not. Such luminance unevenness can be alleviated to some extent by densely arranging many fluorescent tubes on the back side of the liquid crystal panel.

Further, as a conventional technique, an LED panel that divides and emits illumination light into a plurality of regions, and a luminance distribution calculation unit that determines the brightness of the illumination light for each region based on image signals corresponding to the plurality of regions. A backlight control unit that controls illumination light for each area of the illumination unit based on the determination of the luminance distribution calculation unit, and an image correction unit that corrects an image signal input to the light modulation element based on the determination of the luminance distribution calculation unit Is known (see Patent Document 1).
As another prior art, in a backlight for a liquid crystal display device using a light guide plate and a plurality of light emitting diodes as a light source, the surface of the light guide plate is made brighter than the central portion of the light emitting diode that illuminates the end of the light guide plate. Is known (see Patent Document 2).
JP-A-2005-258403 JP 2001-66569 A

The conventional method of increasing the number of fluorescent tubes can alleviate the luminance unevenness, but the product unit price of the liquid crystal panel increases as the number of fluorescent tubes increases, aiming to reduce manufacturing costs. It was a tricky technique in some cases.
In addition, the adjustment to the backlight and the input image signal in Documents 1 and 2 is not performed based on the actual brightness of the screen when the image is displayed on the screen of the image display device. It was lacking in accuracy in terms of correction.

  The present invention has been made in view of the above problems, and it is possible to reduce the number of fluorescent tubes serving as backlights, and to reduce luminance unevenness on the screen of the liquid crystal panel while reliably reducing the manufacturing cost of the product. An object is to provide a system and a liquid crystal television.

  In order to achieve the above object, the present invention provides a luminance correction system for correcting luminance unevenness of a screen of a liquid crystal panel including a direct type backlight unit in which a plurality of fluorescent tubes are arranged at a predetermined interval on the back side. In this system, when the image display means displays a predetermined test image on the screen, the brightness measurement means measures the brightness of the screen on which the test image is displayed for each area on the screen. Next, the correction data generation means inputs the measured luminance of each area of the screen, and generates correction data for each area according to the luminance of each area for reducing luminance unevenness between the areas. . Then, the luminance correction means acquires the correction data and corrects the luminance of the image data representing an arbitrary image displayed on the liquid crystal panel for each region based on the correction data.

That is, according to the present invention, since the luminance of the screen of the liquid crystal panel that actually displays the test image is measured for each region, the luminance unevenness between the regions of the screen can be accurately grasped. If the correction data is generated for each area according to the brightness of each area, then when displaying an arbitrary image on the liquid crystal panel, the brightness of the image data is corrected for each area based on the correction data. Thus, it is possible to perform display in which luminance unevenness is eliminated on the entire screen.
In the present invention, the brightness of the image data given to the liquid crystal panel is corrected for each area of the screen to eliminate the brightness unevenness, so that the brightness of the screen is uniform regardless of the number of fluorescent tubes as backlights. Can be. Therefore, it is possible to avoid an increase in the manufacturing cost of the liquid crystal panel, which has been caused by increasing the number of fluorescent tubes as in the conventional case, and it is possible to manufacture a liquid crystal panel or a liquid crystal television at a lower cost.

  The correction data generation means uses the area where the measurement result has the lowest luminance as the reference area, and sets correction data for eliminating the difference between the luminance of the reference area and the luminance of each area other than the reference area as the area other than the reference area. It may be generated every time. For example, when a white image is displayed on the entire screen as a test image, if a luminance difference occurs between the regions in the measurement result, the low luminance region cannot be brightened any more. Therefore, by generating correction data for reducing the brightness of each area other than the reference area to the brightness of the reference area according to the measured brightness for each area other than the reference area, the brightness unevenness of the screen can be reliably ensured. Can be resolved.

  If the brightness of the other areas is reduced in accordance with the area where the measurement result has the lowest brightness, the brightness of the screen is made uniform (removal of uneven brightness), but the entire screen becomes darker. There is a risk of passing. Therefore, the correction data generation means specifies the reference luminance included between the lowest value and the highest value in the measurement result of each region, and the measurement result of the reference luminance and each region is higher than the reference luminance. Correction data for eliminating the difference from the brightness of the area may be generated for each area whose measurement result is higher than the reference brightness. According to such a configuration, uneven brightness of the screen can be eliminated to some extent, and the brightness of the screen can be secured. That is, it is possible to achieve both the elimination of uneven brightness and the comfort of viewing the screen.

  Here, the reference luminance may be an average value of measurement results of luminance in each region. That is, the correction data generation means calculates the average value, and generates correction data for eliminating the difference between the average value and the luminance of the region where the measurement result is higher in luminance than the average value. Also good. By adopting such a configuration, it is possible to achieve an appropriate balance between eliminating the luminance unevenness of the screen and ensuring the brightness of the screen.

  In some cases, it is easier for the viewer to see the brightness near the center of the screen than at the periphery of the screen. Therefore, the correction data generation means determines whether or not the area for which correction data is to be generated is an area belonging to a preset central range of the screen. The correction data may not be generated. The correction data basically reduces the luminance of the image data in the corresponding area. Therefore, it is possible to ensure comfort when viewing the screen by not generating correction data for the region belonging to the central range of the screen.

  There are various ways to divide each area when the luminance measuring means measures the luminance of the screen, but the luminance measuring means is on the screen including an area that overlaps the position of the fluorescent tube and an area that does not overlap the position of the fluorescent tube. The luminance may be measured for a plurality of regions. In other words, there is a difference in brightness between the area that overlaps the position of the fluorescent tube and the area that does not overlap the position of the fluorescent tube, so if correction data is generated by measuring the brightness for each such area, Appropriate brightness correction can be executed, and the uneven brightness on the screen can be solved accurately.

Here, as a more specific invention based on each of the above-described configurations, a liquid crystal television that corrects luminance unevenness on the screen of a liquid crystal panel including a direct-type backlight unit in which a plurality of fluorescent tubes are arranged at a predetermined interval on the back side In John ’s brightness correction system,
The test image data prepared in advance is output to the liquid crystal panel drive circuit, and the liquid crystal panel drive circuit is driven and controlled on the basis of the image data for the test image, thereby displaying a white test image on the liquid crystal panel screen. When the brightness correction data corresponding to each area of the screen is input from the connected computer, the brightness correction data is stored in a predetermined storage area, and image data indicating an arbitrary image to be displayed on the liquid crystal panel Is inputted, the luminance of the inputted image data is corrected for each region based on the luminance correction data and outputted to the liquid crystal panel driving circuit, and the liquid crystal panel is 15 type and the fluorescent tube is The brightness of the four liquid crystal televisions and the screen on which the test image is displayed, and the region overlapping the position of the fluorescent tube and the fluorescence The color analyzer that measures the brightness of each of the plurality of areas on the screen including the area that does not overlap with the position of the position by moving the probe relative to each other, and the brightness of each of the above areas measured by the color analyzer is input. Calculate the average value of the brightness of the area, select the area where the brightness measurement result is higher than the average value and does not belong to the preset central range of the screen of the liquid crystal panel, and calculate the average value And a computer that generates brightness correction data for each selected area to eliminate the difference between the brightness of each selected area and outputs the generated brightness correction data to the liquid crystal television. can do.

That is, according to the brightness correction system of the above-mentioned liquid crystal television, the brightness of the screen of the liquid crystal panel that actually displays the test image is measured for each area, and the image data is generated by the brightness correction data generated according to the brightness of each area Because the brightness of the LCD is corrected for each area, even if the number of fluorescent tubes as backlights is small, it is possible to eliminate the brightness unevenness of the screen. As a result, the brightness unevenness is reduced and the manufacturing cost of the LCD television is reduced. And both.
It should be noted that the liquid crystal television constituting the liquid crystal television brightness correction system can also be regarded as one invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an outline of the brightness correction system 100. The system 100 generally includes a liquid crystal television 10, a color analyzer 20, and a computer 30.
First, the configuration of the liquid crystal television 10 will be described. In the liquid crystal television 10, the microcomputer 15 is connected to each part constituting the liquid crystal television 10 via the bus 14, and the CPU 15a uses the RAM 15c as a work area and follows a program stored in a storage area such as the ROM 15b. Execute control. The microcomputer 15 is connected to the I / Fs 16 and 17. The I / F 16 is a remote control I / F and receives an input signal from an external remote control transmitter. The I / 17 is connected to the cable 40 extended from the computer 30, and the liquid crystal television 10 receives various instruction signals and data from the computer 30 via the cable 40 and the I / F 17.

  The pixel number conversion circuit 11 inputs digital image data composed of RGB signals representing an arbitrary image, performs a predetermined scaling process on the image data, and has a pixel number suitable for the number of pixels of the liquid crystal panel 13c. Generate image data. The image quality adjustment circuit 12 performs various processes such as brightness correction, contrast adjustment, and saturation correction on the image data output from the pixel number conversion circuit 11, and then outputs the processed image data to the liquid crystal module 13. Output. The liquid crystal module 13 includes a liquid crystal panel 13c, a backlight unit 13b, and a panel drive circuit 13a. In the present embodiment, the liquid crystal panel 13c is a 15-type active matrix driving type panel. The panel driving circuit 13a includes a horizontal scanning circuit and a vertical scanning circuit, and is controlled based on the image data output from the image quality adjustment circuit 12 to drive the liquid crystal panel 13c, thereby causing the liquid crystal panel 13c to respond to the image data. Display an image.

The backlight unit 13b is a light source that irradiates the liquid crystal panel 13c from the back side, and includes a plurality of fluorescent tubes, an inverter that supplies an AC voltage to the fluorescent tubes, and the like. In the present embodiment, the backlight unit 13b has a so-called direct structure, and includes four fluorescent tubes, and these four fluorescent tubes are arranged at substantially constant intervals on the back side of the liquid crystal panel 13c. . The number of four is a small number of light sources for a 15-inch liquid crystal panel. However, as will be described later, in this embodiment, the screen brightness of the liquid crystal panel 13c is made uniform even in a situation where the number of fluorescent tubes is small. Has succeeded.
The image data input to the pixel number conversion circuit 11 is generated by performing demodulation processing by a known demodulation circuit (not shown) on a television broadcast signal received by a known antenna and tuner circuit (not shown). Data.

Next, the color analyzer 20 and the computer 30 will be described.
The color analyzer 20 includes a probe 20a as a detection unit. The probe 20a includes an objective lens and various sensors inside a cylindrical shape. By bringing the probe 20a closer to the measurement point on the screen of the liquid crystal panel 13c, the color analyzer 20 can calculate the luminance of the measurement point based on the signal detected by the probe 20a. Although one probe 20a is displayed in the figure, the color analyzer 20 can be connected to a plurality of probes 20a, and can calculate the luminance of a plurality of measurement points based on output values from each probe 20a.

  The computer 30 inputs the luminance calculated by the color analyzer 20. The computer 30 includes a CPU 31, a ROM 32, a RAM 33, and a hard disk (HD) 35, as in a general computer, and each unit is connected by a bus 36. The HD 35 stores a correction data generation program 35a, and the computer 30 executes generation processing of luminance correction data (hereinafter simply referred to as correction data) according to the program 35a. The computer 30 includes an I / F 34 connected to the cable 40, and outputs the generated correction data to the liquid crystal television 10 via the I / F 34 and the cable 40.

Next, a correction data generation process executed using the system 100 will be described.
In this process, first, the liquid crystal television 10 displays a predetermined test image on the liquid crystal panel 13c. Various variations of the color and the image pattern are conceivable as the test image. In the present embodiment, a test image of one white color (hereinafter referred to as a white image) is displayed. Test image data 18 a for displaying such a white image is stored in advance in a memory 18 provided in the liquid crystal television 10. Accordingly, the microcomputer 15 acquires the test image data 18a from the memory 18 and outputs the test image data 18a to the pixel number conversion circuit 11 to display a white image based on the test image data on the liquid crystal panel 13c. The microcomputer 15 may start the process of displaying the test image in response to an instruction signal transmitted from an external remote control transmitter, or may be started in response to an instruction signal transmitted from the computer 30.

  Since the test image data 18a is data in which the R, G, B values of all the pixels are all the maximum gradation values, the brightness of the screen of the liquid crystal panel 13c is basically determined by the backlight unit 13b. It can be said that the brightness of the irradiating light itself. When a white image is displayed, it is desirable that the screen brightness of the liquid crystal panel 13c be uniform regardless of the location. However, as described above, due to the arrangement and number of fluorescent tubes in the backlight unit 13b, there is a high possibility that luminance unevenness occurs on the screen of the liquid crystal panel 13c at the stage where the white image is simply displayed.

Let us move on to the description of the processing that the color analyzer 20 and the computer 30 are responsible for.
FIG. 2 is a flowchart showing the content of the correction data generation process executed by the computer 30 in accordance with the correction data generation program 35a.
First, in step S (hereinafter, description of steps is omitted) 200, the computer 30 inputs the luminance for each area on the screen of the liquid crystal panel 13c from the color analyzer 20 and stores it in the HD 35.

FIG. 3 shows a part of the liquid crystal panel 13c from the front, and shows a plurality of regions R partitioned on the panel.
In the figure, the position of the fluorescent tube 13b1 disposed on the back side of the liquid crystal panel 13c is indicated by a chain line. The respective fluorescent tubes 13b1 are arranged substantially parallel to each other with a substantially constant distance from each other in the horizontal direction. Further, in the same figure, the dividing line of each region R whose luminance is measured by the color analyzer 20 is indicated by a two-dot chain line. That is, when the probe 20a is brought closer to each region R on the screen divided as shown in FIG. The luminance is measured, and the measured luminance is output to the computer 30 in accordance with a request from the computer 30.

  Various modes can be considered for the number and size of the regions R. In the present embodiment, at least the regions overlapping with the position of the fluorescent tube 13b1 on the back side (R5 to R8, R13 to R16 in the example in the figure), Each region R is determined by dividing the screen by the fineness at which regions (R1 to R4 and R9 to R12 in the example in the figure) that do not overlap with the position of the fluorescent tube 13b1 on the back side are generated.

  When measuring the brightness of each region, the probe 20a may be manually moved by the operator according to a predetermined order with respect to each region, or the computer 30 is a predetermined driving device that realizes movement and stop of the probe 20a. The position determination of the probe 20a with respect to each region may be automated by controlling. In this embodiment, each area is uniquely assigned a number in advance according to its position, and when the computer 30 inputs the luminance from the color analyzer 20, the luminance is measured for the area where the luminance is measured. After associating with a number, it is stored in the HD 35. Specifically, when the operator moves the probe 20a with respect to each area and performs measurement, the operator inputs the area number to the computer 30 each time one area is measured. 30 stores the luminance input from the color analyzer 20 and the number input by the operator in a one-to-one correspondence.

  On the other hand, when the movement of the probe 20a with respect to each region is automated by the control of the computer 30, the computer 30 recognizes which number of the region the probe 20a is relative to at that time. Each time when the luminance is input from the color analyzer 20, the number corresponding to the recognized area is associated with the input luminance and stored. As a result of the above processing, for example, when the number of regions is 48, the luminance data for 48 regions are stored in the HD 35 in a state of being associated with the region numbers 1 to 48 on a one-to-one basis.

  In S <b> 210, the computer 30 identifies an area for which correction data is to be generated among the areas. Here, the computer 30 sets the region where the lowest luminance among the luminances of the respective regions is measured as the reference region Rst, and specifies a region other than the reference region Rst as a correction data generation target region.

FIG. 4A shows the measured luminance for each region on the screen of the liquid crystal panel 13c.
For the sake of simplicity, the figure shows a case where the luminance is measured by dividing the screen into 12 regions. In each region, the luminance of the region where the highest luminance is measured is 100%. In this case, the brightness level is indicated by a number (%). In this figure, since 80% is the minimum luminance, each region corresponding to 80% is the reference region Rst, and other regions where measurement luminance higher than 80% is obtained are regions for which correction data is to be generated. It becomes.

In S220, the computer 30 calculates a difference from the luminance of the reference region Rst for each region specified as a correction data generation target. In other words, if the luminance is 100%, the calculated difference is 20%, and if the luminance is 90%, the calculated difference is 10%.
In S230, the computer 30 generates correction data according to the calculated luminance difference for each area specified as a correction data generation target. Here, the correction data can be regarded as a correction value for the luminance of each pixel constituting the image data handled by the liquid crystal television 10, and as an example, the luminance value of each pixel has a predetermined gradation number (for example, 0 to 0). Correction data is also expressed by the number of gradations.

  For an area where the difference from the brightness of the reference area Rst is 20%, the brightness can be unified with the reference area Rst by reducing the brightness by 20%. In this case, the computer 30 can cope with a 20% brightness drop. The gradation value to be determined is determined, and the determined gradation value is used as correction data. Similarly, for a region where the difference from the luminance of the reference region Rst is 10%, the luminance is decreased by 10% when the luminance of the region where the highest luminance is measured is 100%. Therefore, the gradation value corresponding to the 10% reduction in luminance is determined, and the determined gradation value is used as the correction data. Note that the computer 30 is provided in advance with a table defining the correspondence between the luminance difference and the gradation value as correction data corresponding to the luminance difference, and the calculated luminance difference by referring to the table. The correction data corresponding to is generated.

In S240, the computer 30 outputs the correction data for each area generated in S230 to the liquid crystal television 10 via the I / F 34 and the cable 40. At this time, the computer 30 adds data indicating the number of the region for which correction data is generated to the correction data, and then outputs the correction data to the liquid crystal television 10.
On the liquid crystal television 10 side, each correction data acquired from the computer 30 is stored in a predetermined storage area such as the memory 18.

Next, luminance correction processing on the liquid crystal television 10 side will be described.
FIG. 5 is a flowchart showing image data luminance correction processing executed by the liquid crystal television 10.
In S300, the image quality adjustment circuit 12 determines whether or not image data for one screen has been input from the preceding pixel number conversion circuit 11, and if so, in order to perform luminance correction on the image data as a target, S310. Proceed to That is, after the correction data is acquired from the computer 30, when the image data indicating an arbitrary image to be displayed on the liquid crystal panel 13c is input, the liquid crystal television 10 has the luminance for each screen in the image quality adjustment circuit 12. Correction is performed based on the correction data.

  In S310, the image quality adjustment circuit 12 divides image data for one screen into a predetermined number of areas and selects one area from the divided areas. The division here is performed in the same section as the section of the area on the screen when the luminance measurement is performed by the color analyzer 20. In other words, the liquid crystal television 10 side also has in advance the partition mode data as to how to partition one screen when the luminance measurement is performed. In S310, an image for one screen is obtained based on the partition mode data. Divide the data into multiple areas. The partition mode data is data that specifies the positions of a plurality of horizontal dividing lines and a plurality of vertical dividing lines when dividing one screen into a plurality of rectangular areas.

  In addition, the liquid crystal television 10 has data as a correspondence relationship between the divided areas and the numbers to be assigned to the areas, and assigns a unique number corresponding to the position of each divided area. . Needless to say, the correspondence between each area and number is the same as the correspondence between each area and number handled on the computer 30 side.

In S320, the image quality adjustment circuit 12 accesses a predetermined storage area in which correction data is stored, and whether correction data with the same number as the area selected in S310 is stored. to decide.
If correction data with the same number is stored, in S330, the stored correction data is read from the storage area, and the selected area is configured according to the read correction data. The brightness of each pixel is corrected. Here, that correction data is stored for a certain area means that the area is an area other than the reference area Rst. For example, when the correction data has a gradation value n (n is an integer of 0 to 255), the luminance is corrected by reducing the luminance value of all the pixels constituting the selected area by n.

On the other hand, if it is determined in S320 that correction data with the same number as that of the selected area is not stored, S330 is skipped. In this case, the region selected in S310 is the reference region Rst.
In S340, the image quality adjustment circuit 12 determines whether or not the processing from S310 onward has been performed for all the areas obtained by dividing the image data for one screen, and returns to S310 if an unprocessed area remains. One area is newly selected from the unprocessed areas. On the other hand, if it is determined that the processing from S310 onward has been performed for all regions, the process proceeds to S350, and the image data is output to the liquid crystal module 13 at the subsequent stage.

According to the above correction process, with respect to image data corresponding to an area other than the reference area Rst, the luminance of each pixel is reduced according to the correction data corresponding to that area, so that in the image displayed on the liquid crystal panel 13c, The brightness of each region matches the level of the reference region Rst.
FIG. 4B shows the luminance measured by the color analyzer 20 for each region when the test image data 18a is subjected to the above correction processing and a white image is displayed on the liquid crystal panel 13c. As shown in the figure, in the screen after the above correction processing, the measured luminance in all the regions is unified to 80% when the maximum luminance in the screen displaying the white image before the correction processing is 100%. Is done.

  As described above, in the present invention, since the number of fluorescent tubes arranged at a predetermined interval on the back surface of the liquid crystal panel 13c is smaller than usual, luminance unevenness is likely to occur in each region of the liquid crystal panel 13c. Measures the brightness of each screen area when the test image is actually displayed, and generates brightness correction data for unifying the screen brightness to a specific level according to the size of the measured brightness. In the image display process in the liquid crystal television 10, the brightness of the image data relating to the display target image is corrected for each area using the brightness correction data for each area. Therefore, it is possible to eliminate the uneven brightness on the screen that may occur due to the low arrangement density of the fluorescent tubes without increasing the number of fluorescent tubes and increasing the manufacturing cost of the liquid crystal television 10. became.

  Note that the luminance correction data generation processing executed using the system 100 is performed for each product in a factory before the product (liquid crystal television 10) is shipped, so that the luminance unevenness of the screen when an image is displayed for each product. Can be eliminated.

Furthermore, another embodiment of the present invention will be described.
FIG. 6 shows a correction data generation process executed by the computer 30 in accordance with the correction data generation program 35a, and shows an example different from the flowchart of FIG.
First, in S400, as in S200, the brightness of each area on the screen is input from the color analyzer 20 that measures the brightness of the screen of the liquid crystal panel 13c displaying the white image. Hereinafter, differences from FIG. 2 will be described.

In S410, the computer 30 calculates an average value (reference luminance) of luminance data for each region.
In S420, the computer 30 selects an area where the measured luminance is higher than the average value from each area, and specifies each selected area as an area for generating correction data.
Referring to FIG. 4 (a), there are four regions with measured luminances of 100%, 90%, and 80%, respectively, and the average value thereof is 90%. Therefore, when a measurement result as shown in FIG. 4A is obtained, an area having a luminance of 100% that is higher than the average value is specified as a correction data generation target area.

  In S430, the computer 30 calculates a difference from the average value for each area specified as a correction data generation target. If it demonstrates with reference to Fig.4 (a), since it is set as the production | generation object of correction data only about the area | region where a brightness | luminance is 100%, all the brightness | luminance differences calculated about each area | region are 10%.

  In S440, the computer 30 generates correction data according to the luminance difference from the calculated average value for each area specified as a correction data generation target. That is, unlike FIG. 2, the brightness of other areas is not adjusted to the area where the measured brightness is lowest, but is adjusted to an intermediate value of the measured brightness so that the entire screen does not become too dark. Yes. Here again, as in S230, the computer 30 generates correction data for each region by referring to the table defining the correspondence between the luminance difference and the gradation value corresponding to the luminance difference.

The correction data is output to the liquid crystal television 10, and the luminance correction processing shown in FIG. As a result, for the region where the measured luminance is higher than the average value, the luminance of each pixel is lowered according to the correction data corresponding to the region.
FIG. 7 shows a color analyzer for each region when the test image data 18a is subjected to correction processing using the correction data generated in the processing of FIG. 6 and a white image is displayed on the liquid crystal panel 13c. The measurement brightness | luminance by 20 is shown.

  As shown in the figure, on the screen after the correction process, the brightness in the region where the measured brightness is higher than the average value (90%) described with reference to FIG. The measured brightness for the region that was 100% has dropped to the average value. That is, according to this embodiment, the luminance unevenness of the entire screen is not completely eliminated, but the width of the luminance variation across the entire screen is reduced to reduce the luminance unevenness, and the screen becomes dark overall. It is not too much, and overall viewing comfort is ensured.

Furthermore, the following configurations can be added to the above embodiments.
In general, in consideration of comfort when a user views a TV screen, it is desirable to maintain a state of high brightness as much as possible near the center of the screen. Therefore, in the correction data generation process, the computer 30 may exclude a region belonging to a preset center range of the screen from a correction data generation target. Specifically, immediately after S210 in FIG. 2 or immediately after S420 in FIG. 6, “is it an area belonging to the central range of the screen?” For each area specified as a correction data generation target in S210 or S420. The region for which “belongs” is determined is excluded from the correction data generation processing target after S220 or S430.

  Note that the computer 30 includes in advance the central range number data specifying the number of the region belonging to the central range of the screen among the numbers uniquely determined according to the position of each region of the screen in the HD 35 in advance. deep. Then, for each area specified as the correction data generation target in S210 or S420, it is determined whether or not the number of the area matches any of the numbers indicated by the central range number data, thereby generating correction data. It may be determined whether or not to be excluded from the target.

  As a result of such processing, if the brightness of the screen when the test image is displayed belongs to the central range even if the brightness is higher than the brightness of the reference area Rst or the average value, the brightness of the image data Luminance reduction due to correction is avoided. Therefore, in the liquid crystal television 10, it is possible to perform screen display in which the luminance unevenness of the entire screen is suppressed to some extent while maintaining high luminance near the center of the screen.

The block diagram which showed the outline of the brightness correction system. The flowchart which showed an example of the correction data generation process. The figure which showed a part of liquid crystal panel. The figure which showed the measurement brightness | luminance of the liquid crystal panel for every area | region. The flowchart which showed the content of the brightness correction process. The flowchart which showed the other example of the correction data generation process. The figure which showed the measurement brightness | luminance of the liquid crystal panel for every area | region.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal television 12 ... Image quality adjustment circuit 13 ... Liquid crystal module 13a ... Panel drive circuit 13b ... Backlight unit 13b1 ... Fluorescent tube 13c ... Liquid crystal panel 15 ... Microcomputer 18 ... Memory 18a ... Test image data 20a ... Probe 20 ... Color analyzer 30 ... Computer 35 ... HD
35a ... Correction data generation program 100 ... Luminance correction system

Claims (8)

In a luminance correction system of a liquid crystal television that corrects luminance unevenness of a screen of a liquid crystal panel including a direct backlight unit in which a plurality of fluorescent tubes are arranged at a predetermined interval on the back side,
The test image data prepared in advance is output to the liquid crystal panel drive circuit, and the liquid crystal panel drive circuit is driven and controlled on the basis of the image data for the test image, thereby displaying a white test image on the liquid crystal panel screen. When the brightness correction data corresponding to each area of the screen is input from the connected computer, the brightness correction data is stored in a predetermined storage area, and image data indicating an arbitrary image to be displayed on the liquid crystal panel Is inputted, the luminance of the inputted image data is corrected for each region based on the luminance correction data and outputted to the liquid crystal panel driving circuit, and the liquid crystal panel is 15 type and the fluorescent tube is 4 liquid crystal televisions,
The brightness of a plurality of areas on the screen including the area that overlaps the position of the fluorescent tube and the area that does not overlap the position of the fluorescent tube are made relative to each other while moving the probe. A color analyzer to measure with
The brightness of each area measured by the color analyzer is input and the average value of the brightness of each area is calculated. The brightness measurement result of each area is higher than the average value, and the liquid crystal panel is set in advance. Select an area that does not belong to the center range of the screen, generate brightness correction data for eliminating the difference between the average value and the brightness of each selected area, and generate the generated brightness correction data A computer that outputs to an LCD television;
A brightness correction system for a liquid crystal television, comprising: In a luminance correction system for correcting luminance unevenness of the screen of a liquid crystal panel provided with a direct backlight unit in which a plurality of fluorescent tubes are arranged at a predetermined interval on the back side,
Image display means for displaying a predetermined test image on the screen;
A luminance measuring means for measuring the luminance of the screen displaying the test image for each area on the screen;
A correction data generating unit that inputs the luminance of each area of the measured screen and generates correction data for each area to reduce luminance unevenness between areas according to the luminance of each area;
A luminance correction system comprising: luminance correction means for correcting the luminance of image data representing an arbitrary image displayed on the liquid crystal panel for each of the regions based on the correction data.   The correction data generation means uses the area where the measurement result has the lowest brightness as a reference area, and sets correction data for eliminating the difference between the brightness of the reference area and the brightness of each area other than the reference area. The brightness correction system according to claim 2, wherein the brightness correction system is generated for each region.   The correction data generation means specifies a reference luminance included between the lowest value and the highest value in the measurement result of each region, and the measurement result of the reference luminance and each region is higher than the reference luminance. The brightness correction system according to claim 2, wherein correction data for eliminating the difference from the brightness is generated for each region whose measurement result is higher than the reference brightness.   5. The luminance correction system according to claim 4, wherein the correction data generation means calculates an average value of measurement results of each region and uses the average value as a reference luminance.   The correction data generation means determines whether or not the area for which correction data is to be generated is an area belonging to a preset central range of the screen, and if it is an area belonging to the central range, 6. The brightness correction system according to claim 3, wherein correction data is not generated.   7. The brightness measurement unit measures brightness for a plurality of areas on a screen including an area overlapping with the position of the fluorescent tube and an area not overlapping with the position of the fluorescent tube. The brightness correction system according to Crab. In a liquid crystal television that corrects luminance unevenness of the screen of a liquid crystal panel provided with a direct type backlight unit in which a plurality of fluorescent tubes are arranged at a predetermined interval on the back side,
The test image data prepared in advance is output to the liquid crystal panel drive circuit, and the test image is displayed on the screen of the liquid crystal panel by controlling the drive of the liquid crystal panel drive circuit based on the image data for the test image,
When luminance correction data for each region for reducing luminance unevenness between regions generated according to the luminance obtained by luminance measurement for each region on the screen displaying the test image is input from the outside Save the correction data in a predetermined storage area,
When image data indicating an arbitrary image to be displayed on the liquid crystal panel is input, the luminance of the input image data is corrected for each region based on the luminance correction data and output to the liquid crystal panel drive circuit. A liquid crystal television characterized by that.

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