JP2010014800A - Brightness control circuit and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost liquid crystal display that does not require a high-speed operational device, while reducing the storage capacitance of a storage means for eliminating unevenness in the luminance. <P>SOLUTION: A luminance control circuit 100 includes: a memory 102 that stores an n-bit data for controlling luminance, which is preliminarily set in each line where a video signal is inputted in a display panel, capable of displaying an m-bit grayscale, wherein m is an integer of 2 or more and n is an integer of 1 or more satisfying the relation m>n; and a color grayscale extension circuit 101 that reads out the n-bit data for controlling luminance from the memory 102; and the data mapped to input line information of the display panel included in the m-bit grayscale video signal, extends the grayscale number of the video signal to m+L bits, wherein n≥L>1, selects a grayscale data in m bits preliminarily determined by the data for controlling luminance from the extended (m+L)-bit grayscale video signal, and outputs the data as an m-bit grayscale video signal to the display panel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a luminance adjustment circuit and a liquid crystal display device that adjust luminance unevenness of a liquid crystal display panel.

  In recent years, liquid crystal display devices have become thinner and larger, and their demand has increased. Along with this, higher quality display performance is required more than ever.

  However, the liquid crystal panel provided in the liquid crystal display device has uneven luminance in the display area due to some factor during production, and deteriorates the display quality. In particular, in the liquid crystal panel, the uneven luminance generated in the stripe shape is conspicuous, and the display quality is remarkably lowered by the uneven luminance in the stripe shape.

  For example, as shown in FIG. 9, in the display region 501 of the TFT panel 500, a region 501a in which the luminance value is uniformly smaller or larger than the reference luminance value in the arrow Y direction (the direction along the source line) exists in a streak shape. To do. Such a streak-shaped area having a luminance value different from that of the surrounding area is hereinafter referred to as luminance unevenness 501a. Here, the reference luminance value is a luminance value obtained when the entire TFT panel is displayed with the same gradation.

  In order to eliminate the luminance unevenness, the luminance value of the video signal input to the liquid crystal panel is usually adjusted. For example, if the brightness value of the area corresponding to a certain source line is smaller than the reference brightness value, the area is judged to be darker than the surrounding area, and the brightness value of the video signal input to the source line is adjusted to be larger. On the other hand, if the luminance value of the area corresponding to the source line is larger than the reference luminance value, it is determined that the area is brighter than the surrounding area, and the luminance value of the video signal input to the source line is reduced. Adjust to. Specifically, luminance unevenness is eliminated by converting the gradation data of the video signal input to each source line in accordance with the luminance value of the region corresponding to each source line.

  By the way, since the region where the luminance unevenness is generated is different for each liquid crystal panel, the above-mentioned gradation data conversion data (hereinafter referred to as luminance adjustment data) is prepared for each source line for each liquid crystal panel. It is necessary to memorize in the panel. Alternatively, it is necessary to calculate an average value for a certain number of panels and store the same data in the target panel.

  However, as the size and resolution of the liquid crystal panel increase, the number of source lines increases, and the number of brightness adjustment data increases accordingly. For this reason, there is a problem that the storage capacity of the brightness adjustment data is increased.

Therefore, for example, in Patent Document 1, a part of conversion data (corresponding to the above-described brightness adjustment data) for performing gradation correction is stored in a storage means (RAM or the like), and interpolation processing is performed on the remaining conversion data. A technique for reducing the storage capacity of the storage means by calculating and obtaining the above is disclosed.
JP 2000-338935 (released on December 8, 2000)

  However, in Patent Document 1, although the storage capacity of the storage means can be reduced, since a part of the conversion data is obtained by interpolation calculation, the number of source lines that increase as the liquid crystal panel increases in size and definition, Further, the increase in the driving speed of the liquid crystal panel necessitates an increase in the above-mentioned interpolation calculation. For this purpose, an expensive arithmetic device capable of high-speed calculation or a complicated arithmetic circuit is required, which raises a problem that the price of the liquid crystal display device increases.

  The present invention has been made in view of the above problems, and an object thereof is to provide an inexpensive liquid crystal display device that does not require a high-speed arithmetic device while reducing the storage capacity of the storage means. The object is to realize a luminance adjustment circuit.

In order to solve the above-described problem, a luminance adjustment circuit according to the present invention is a luminance adjustment circuit that adjusts the luminance of a video signal input to a display panel capable of displaying m (m: integer of 2 or more) bit gradation.
In order to eliminate the luminance unevenness on the display panel, the display panel satisfies the relationship of n (n: 1 or more and m> n) set in association with each line to which the video signal is input. An integer) bit storage means for storing brightness adjustment data;
The n-bit brightness adjustment data associated with the input line information of the display panel included in the video signal of m-bit gradation is read from the storage means, and the number of gradations of the video signal is (m + L: n ≧ L > 1) Expand to bits, select m-bit gradation determined in advance by the brightness adjustment data from the expanded (m + L) -bit gradation video signal, and display the above as m-bit gradation video signal And a gradation expanding means for outputting to the panel.

  According to the above configuration, the video signal output to the display panel is set in association with each line of the display panel to which the video signal is input in order to eliminate luminance unevenness on the display panel. Since the luminance is adjusted based on the luminance adjustment data, if the video signal is input to the display panel, the luminance unevenness is eliminated and a display image with high display quality can be obtained.

  In addition, the luminance-adjusted video signal that is finally input to the display panel is stored from the data expanded by the gradation expanding means (the m-bit gradation video signal is temporarily (m + L) -bit gradation data). This is determined by selecting m-bit gradation data determined in advance by n-bit brightness adjustment data associated with line information to which the video signal is input, which is stored in advance in the means.

  Here, since the brightness adjustment data stored in the storage means has a bit number n smaller than the bit number m of the input video signal, the capacity of the storage means can be reduced.

  In addition, the gradation expansion means increases the number of gradations of the input video signal, refers to the storage means, selects the original gradation number of the video signal, and obtains the brightness-adjusted video signal. Therefore, it is not necessary to perform complicated operations such as data interpolation. Thereby, even a relatively inexpensive arithmetic device can perform gradation expansion processing in the gradation expansion means, so that an inexpensive liquid crystal display device can be provided.

  The gradation expanding means reads n-bit luminance adjustment data associated with the input line information of the display panel included in the m-bit gradation video signal from the storage means, and The logarithm is expanded to (m + n) bits, m-bit gradations determined in advance by the luminance adjustment data are selected from the expanded (m + n) -bit gradation video signals, and an m-bit gradation video signal is selected. May be output to the display panel.

  When the display panel is a liquid crystal display panel, the luminance adjustment data is preferably generated based on a luminance value obtained from an area corresponding to each source line of the liquid crystal display panel.

  In this case, it is possible to eliminate luminance unevenness composed of streaky regions generated in the vertical direction of the display screen (direction along the source line) among luminance unevenness generated in the liquid crystal display panel.

  The liquid crystal display panel generates the brightness adjustment data from a light receiving element that receives irradiation light from a display area corresponding to each source line and light reception data for each source line received by the light receiving element. Preferably, brightness adjustment data generation means is provided, and the storage means stores the brightness adjustment data generated by the brightness adjustment data generation means.

  In this case, it is not necessary to obtain brightness adjustment data in advance and store it in the storage means. In addition, since the liquid crystal display panel is equipped with means for generating brightness adjustment data, it can also eliminate luminance unevenness caused by changes in luminance values in the display area corresponding to each source line in the liquid crystal display panel. can do.

  When the display panel is a liquid crystal display panel, it is preferable that the brightness adjustment data is generated based on a brightness value obtained from a region corresponding to each gate line of the liquid crystal display panel.

  In this case, of the luminance unevenness generated in the liquid crystal display panel, it is possible to eliminate the luminance unevenness composed of streaky regions generated in the horizontal direction of the display screen (the direction along the gate line).

  The liquid crystal display panel includes a light receiving element that receives irradiation light from a display region corresponding to each gate line, and brightness adjustment that generates the brightness adjustment data from light reception data for each gate line received by the light receiving element. It is preferable that brightness adjustment data generated by the brightness adjustment data generation means is stored in the storage means.

  In this case, it is not necessary to obtain brightness adjustment data in advance and store it in the storage means. In addition, since the liquid crystal display panel is provided with means for generating brightness adjustment data, it can also eliminate luminance unevenness caused by changes in luminance values over time in the display area corresponding to each gate line in the liquid crystal display panel. can do.

  As described above, the luminance adjustment circuit according to the present invention is a luminance adjustment circuit that adjusts the luminance of a video signal input to a display panel capable of displaying m (m: an integer of 2 or more) bit gradation. N (n is an integer satisfying the relationship of n: 1 or more and m> n), which is set in association with each line to which the video signal is input in the display panel in order to eliminate the luminance unevenness above. Storage unit storing the luminance adjustment data, and n-bit luminance adjustment data associated with the input line information of the display panel included in the m-bit gradation video signal is read from the storage unit, The number of gradations of the video signal is expanded to (m + L: n ≧ L> 1) bits, and the gradation of m bits determined in advance by the luminance adjustment data from the expanded (m + L) bit gradation video signal. Select m And a gray scale expansion means for outputting to the display panel as a video signal of high gray scales. Therefore, it is possible to eliminate luminance unevenness occurring in the display panel and to provide an inexpensive liquid crystal display device. There is an effect that can be done.

  An embodiment of the present invention will be described as follows. In the present embodiment, a luminance adjustment circuit used in a liquid crystal display device using a liquid crystal display panel as the display panel will be described. Further, the liquid crystal display panel is a liquid crystal display panel capable of displaying m = 8 bit gradation among display panels capable of displaying m (m: integer of 2 or more) bit gradation.

  As shown in FIG. 2, the liquid crystal display device according to the present embodiment includes a TFT (Thin Film Transistor) panel 1 as a display panel, and a source drive circuit 2 and a gate drive as drive circuits for driving the TFT panel 1. The circuit 3 and the timing control circuit 4 are provided.

  The TFT panel 1 is a display panel capable of 8-bit gradation display, and has a plurality of source lines connected to the source driving circuit 2 and a plurality of gate lines connected to the gate driving circuit 3. The liquid crystal is sandwiched between a TFT substrate provided with a TFT element and a pixel electrode as a switching element at each intersection of the source line and the gate line, and a counter substrate facing the TFT substrate.

  The gate line, the source line, and the pixel electrode are respectively connected to the gate electrode, the source electrode, and the drain electrode of the switching element in the TFT substrate. Thus, whether or not a source signal, that is, a video signal is supplied to the pixel electrode is controlled by on / off control of the switching element. For example, when a gate signal is supplied from the gate driving circuit 3 to the switching element via the gate line, the switching element is turned on, and the source signal flows from the source electrode to the drain electrode of the switching element and is supplied to the pixel electrode. The

  The source signal is supplied from the source driving circuit 2 through a source line.

  Based on the timing signal supplied from the timing control circuit 4, the source driving circuit 2 supplies the source signal to each source line of the TFT substrate in the TFT panel 1 in the scanning order.

  As shown in FIG. 3, the timing control circuit 4 includes a luminance adjustment circuit 100, a video data correction circuit 200, a panel data transmission circuit 300, and a timing generation circuit 400.

  The luminance adjustment circuit 100 is a circuit for adjusting the luminance of the video signal input to the TFT panel 1 and includes a color gradation expansion circuit (gradation expansion means) 101 and a memory (storage means) 102. Yes. Details of the luminance adjustment circuit 100 will be described later.

  The video signal whose luminance is adjusted for each line by the luminance adjustment circuit 100 is supplied to the video data correction circuit 200. Here, the line indicates a source line provided on the TFT substrate in the TFT panel 1.

  The video data correction circuit 200 further performs correction processing in the gamma correction circuit, the color tone correction circuit, the contour correction circuit, and the like on the video signal whose luminance has been adjusted by the luminance adjustment circuit 100, and the corrected video data is converted into the subsequent stage. This circuit supplies the panel data transmission circuit 300 and the timing generation circuit 400.

  The panel data transmission circuit 300 is a circuit that extracts panel data necessary for display on the TFT panel 1 from the corrected video data supplied from the video data correction circuit 200 and transmits the panel data to the source driving circuit 2.

  On the other hand, the timing generation circuit 400 is a circuit that generates a timing signal for timing to send panel data to be supplied to the TFT panel 1 from timing information included in the corrected video data supplied from the video data correction circuit 200. is there.

  That is, the timing control circuit 4 appropriately corrects the luminance of the input video signal, generates panel data and a timing signal from the corrected video data, and supplies each to the source driving circuit 2. It has become.

  In the timing control circuit 4 shown in FIG. 3, an example is shown in which the luminance adjustment circuit 100 is provided in the previous stage of the video data correction circuit 200, but the luminance adjustment circuit 100 is provided in the subsequent stage of the video data correction circuit 200. It may be.

  Here, the brightness adjusting circuit 100 will be described below with reference to FIGS.

  The luminance adjustment circuit 100 includes a color gradation expansion circuit (gradation expansion means) 101 and a memory (storage means) 102 as shown in FIG.

  The color gradation extension circuit 101 is a circuit that performs an extension process of an 8-bit gradation video signal to a pseudo 10-bit gradation video signal for each line in the TFT panel 1 to which a video signal is input. For example, an FRC (Frame Rate Control) circuit can be preferably used, but other circuits may be used as long as the circuit expands the gradation in a pseudo manner. For example, as an example of the FRC circuit, a circuit for performing pseudo 10-bit gradation display on the TFT panel 1 capable of displaying 8-bit gradation by dividing the time into four and expressing gradations of lower 2 bits. There is.

  As shown in FIG. 1B, the color gradation expansion circuit 101 expands an 8-bit input video signal represented by 256 gradations to 1024 gradations of 10-bit gradations and expands pseudo 1024. This is a circuit that selects 256 gradations based on the 2-bit luminance adjustment data stored in the memory 102 from the gradations and outputs a pseudo 10-bit output.

  The memory 102 is storage means for storing 2-bit luminance adjustment data set in advance for each line to which a video signal is input in the TFT panel 1. As the storage means, RAM, ROM or the like can be applied, but it is preferable to use a storage means with a reading speed as fast as possible.

  In the memory 102, 2-bit luminance adjustment data is stored for each source line of the TFT panel 1 as shown in FIG.

  The color gradation expansion circuit 101 reads the brightness adjustment data stored in the memory 102 for each source line, and based on the read brightness adjustment data, the level of the video signal input to the source line. A key is assigned to one of the expanded gradations.

  Specifically, when the brightness adjustment data is 2-bit data as described above, the 2-bit data can be classified into four types of “00”, “01”, “10”, and “11”. For example, as shown in FIG. 5, four gradations (4n gradations) of a 10-bit video signal with respect to one gradation (n gradation: n = 0 to 255) of an 8-bit video signal. 4n + 1 gradation, 4n + 2 gradation, 4n + 3 gradation) are assigned.

  Here, the brightness adjustment data “00” indicates no gradation change, “01” indicates that the gradation is increased by one step when the gradation is changed to 10-bit gradation, and “10” indicates the gradation is changed. When the 10-bit gradation is set, it indicates that the level is increased by two, and “11” indicates that the level is increased by three when the gradation is set to the 10-bit level. That is, in FIG. 5, “00” is associated with the 4n gradation of the 10-bit gradation, “01” is associated with the 4n + 1 gradation, “10” is associated with the 4n + 2 gradation, “11” is associated with the 4n + 3 gradation.

  In other words, if the number of gradations of an input 8-bit gradation video signal is n = 0, there are four gradations of 0 gradation, 1 gradation, 2 gradations, and 3 gradations in the 10-bit gradation. Assigned. When the luminance adjustment data indicating that no gradation change is necessary in the source line is “00”, the 8-bit gradation video signal with n = 0 is assigned to 0 gradation of 10-bit gradation. become.

  As described above, when the brightness adjustment data is 2-bit data, one gradation is selected from four gradations for each gradation. In the case of performing, the gradation is reduced to 6-bit gradation. However, as described above, if the gradation is expanded to 10-bit gradation, the gradation can be left as 8-bit gradation.

  In this embodiment, the case where the luminance adjustment data is 2 bits has been described. However, the present invention is not limited to this. For example, the luminance adjustment data may be 4 bits. In this case, as shown in FIG. 6, one gradation is selected from 12 gradations for each gradation. As described above, by increasing the number of bits of the brightness adjustment data, it is possible to widen the gradation correction range. As described above, the number of bits of the brightness adjustment data and the number of bits for extending the color gradation do not necessarily match. In the example shown in FIG. 6, the number of bits of the luminance gradation data is 4 bits, and the number of bits for extending the color gradation is 2 bits.

  That is, the number of gradations that can be displayed on the display panel is m (m: integer of 2 or more) bits (8 bits in this embodiment), and the number of gradations of luminance adjustment data is n (n: 1 or more, and m> n is an integer satisfying the relationship of n) bits (4 bits in this embodiment), the number of gradations of the video signal is expanded to (m + L: n ≧ L> 1) bits instead of (m + n) bits, From the expanded (m + L (in this embodiment, L = 2)) bit gradation video signal, m-bit gradations determined in advance by the brightness adjustment data are selected, and the above-mentioned m-bit gradation video signal is selected. You may make it output to a display panel.

  As described above, the brightness adjustment data is stored in the memory 102 as a value set in advance for each source line of the TFT panel 1.

  A method of generating brightness adjustment data stored in the memory 102 will be described below with reference to FIG.

  The brightness adjustment data is stored in the memory 102 through the following processing.

  First, luminance data is acquired from the TFT panel 1 (step S1).

  In general, among the luminance variations in the TFT panel 1, the luminance variation that is easily recognized by a person is generated in a line in the direction of the arrow Y, that is, a source line unit to which a video signal is supplied, as shown in FIG. 9.

  Here, as a method for acquiring the luminance data from the TFT panel 1, an image obtained by supplying video signals of the same gradation to the TFT panel 1 all, for example, the entire display area of a white display image is photographed with a camera. There is a method in which luminance data of the entire display area of the TFT panel 1 is collectively acquired by analyzing image data obtained by photographing.

  Alternatively, a method may be used in which brightness data is acquired by scanning the screen for each line (here, source line) of the display area of the TFT panel 1 displaying white.

  The luminance data acquired here is data obtained from an image displayed by supplying video signals of the same gradation to the TFT panel 1 and should therefore show the same luminance value. In this case, it is not necessary to generate brightness adjustment data for adjusting the brightness value. However, the vertical direction (Y direction) or the horizontal direction (X direction) of the TFT panel 1 depends on various factors in the panel manufacturing process. In other cases, the brightness value may be different from that of the other portions. In this case, it is necessary to generate the brightness adjustment data described above.

  Therefore, the brightness adjustment data is generated from the brightness data acquired in step S1 (step S2).

  Here, the brightness adjustment data is generated as correction data suitable for the correction method.

  Specifically, data for adjusting so that the value of the brightness data detected for each source line becomes the reference brightness value is generated as brightness adjustment data.

  The reference luminance value is, for example, the maximum luminance value when the same gradation display is performed in the TFT panel 1 shown in FIG. As a result, the source line recognized as the luminance unevenness 501a appears darker than the source line of the reference luminance value. That is, the luminance value is smaller than the reference luminance value. Then, the 2-bit data “00”, “01”, “10”, and “11” described with reference to FIG. 5 are set for each source line according to the degree to which the luminance value becomes smaller than the reference luminance value. .

  The brightness adjustment data obtained in this way is written into the memory 102 (step S3).

  The above steps S1 to S3 are performed for each TFT panel 1, and the brightness adjustment data is stored in the memory 102 corresponding to each TFT panel 1 as a unique value for each TFT panel 1.

  As described above, in this embodiment, the brightness adjustment of the TFT panel 1 is performed using the brightness adjustment data generated in advance for each TFT panel 1, but the present invention is not limited to this. The brightness adjustment data may be generated by taking out the brightness data of the panel 1 in real time.

  FIG. 8 shows a liquid crystal display device capable of generating luminance adjustment data by taking out luminance data of the TFT panel 1 in real time.

  As shown in FIG. 8, the liquid crystal display device includes a TFT panel 500 including a light receiving unit and a video signal processing circuit 600. The video signal and the brightness adjustment data from the video signal processing circuit 600 are controlled by timing control. It is supplied to the circuit 4. The timing control circuit 4 is the same as the timing control circuit 4 shown in FIG.

  The luminance data of the display area in the TFT panel 500 is acquired by a light receiving unit provided in the TFT panel 500. The luminance data acquired by the light receiving unit is sent to the video signal processing circuit 600.

  The configuration of the light receiving unit and the details of the light receiving mechanism in the TFT panel 500 will be described below.

  As shown in FIG. 10, the TFT panel 500 includes a TFT portion 500c, a liquid crystal layer 500d, and a color filter 500e, which are laminated between a front glass substrate 500a and a back glass substrate 500b in this order from the front glass substrate 500b side. It has been configured.

  A chassis 11 for supporting the TFT panel 500 is provided around the TFT panel 500 as shown in FIGS. The chassis 11 is provided with a bezel 11 a that covers an area other than the display area 501 of the TFT panel 500.

  A light receiving element 502 is provided on the surface of the front glass substrate 500a constituting the TFT panel 500 facing the bezel 11a. A predetermined gap is provided between the bezel 11a and the TFT panel 500.

  On the surface of the bezel 11a of the chassis 11 facing the TFT panel 500, as shown in FIG. 10, a reflection mirror which is a light guide member for reflecting the irradiation light from the TFT section 500c and guiding it to the light receiving element 502. 503 is provided.

  The reflection mirror 503 is disposed at a position for guiding the irradiation light from the region on the source line in the TFT unit 500 c corresponding to the light receiving element 502 to the light receiving element 502. Note that the irradiation light guided to the light receiving elements 502 is preferably irradiation light from all the regions on the source line corresponding to each light receiving element 502, but if the region is on the same source line, the irradiation light from all regions Instead of irradiation light, irradiation light in a part of the region may be used.

  Note that the length of the gap between the bezel 11a and the TFT panel 500 takes into consideration the thickness of the reflection mirror 503 and the thickness at which the reflection mirror 503 can appropriately guide the light emitted from the TFT portion 500c to the light receiving element 502. Determined.

  The light receiving element 502 is composed of, for example, a TFT element, and outputs an electrical signal corresponding to the amount of received light.

  By the way, when video signals of the same gradation are supplied to the TFT panel 500 to all the source lines, the luminance of the video displayed on the TFT panel 500 should be uniform.

  However, in the general TFT panel 500, the luminance is not uniform and unevenness occurs. For example, as shown in FIG. 9, this unevenness has a region in which the luminance value is uniformly lower or higher than the reference luminance value in the arrow Y direction (vertical direction) in the display area 501, resulting in luminance unevenness 501 a. Recognized by the observer.

  The luminance unevenness 501a does not appear periodically, but appears irregularly in the direction of the arrow X as shown in FIG. Further, the position where the luminance unevenness 501a is generated varies depending on individual differences. For this reason, the luminance value is measured for each source line in the TFT panel 500, the extent to which the measured value is different from the reference luminance value is grasped for each TFT panel 500, and the region that becomes the luminance unevenness 501a is specified. Therefore, it is necessary to correct the video signal input to the TFT panel 500.

  In this embodiment, as described above, as shown in FIG. 11, the light receiving elements 102 are provided for each of the 110 columns (source lines) arranged in the direction of the arrow Y, and the region corresponding to each source line is used. Is received by the light receiving element 102 and an electrical signal corresponding to the amount of received light is output, and this electrical signal is used as received light data.

  Processing for obtaining luminance adjustment data from the received light data is performed by the video signal processing circuit 600.

  The video signal processing circuit 600 includes a ROM 602, a RAM 603, a writing interface 604, an image processing LSI 605, and a reading interface 606, with the CPU 601 as the center, and the CPU 601 generates brightness adjustment data.

  That is, in the video signal processing circuit 600, first, the CPU 601 instructs the timing control circuit 4 so that light reception data can be acquired from the light receiving unit provided in the TFT panel 500 via the timing control circuit 4. To do.

  Next, the CPU 601 takes in the received light data acquired by the light receiving unit into the RAM 603 via the reading interface 606.

  Subsequently, the CPU 601 generates brightness adjustment data based on the brightness adjustment data generation program stored in the ROM 602 and the received light data stored in the RAM 603. The brightness adjustment data is generated for each source line of the TFT panel 500.

  Finally, the CPU 601 writes the generated brightness adjustment data into the memory 102 in the timing control circuit 4 via the writing interface 604.

  When the video signal is supplied via the image processing LSI 605 of the video signal processing circuit 600 with the brightness adjustment data written in the memory 102, the timing control circuit 4 applies the video signal to each source line. The luminance adjustment data is read out, and the video signal after the luminance adjustment is supplied to the TFT panel 500.

  Note that it is preferable that the luminance adjustment data generation process be performed at least after the TFT panel 1 is installed in the liquid crystal display device and before the first image display. However, the above processing may be performed after displaying the image once.

  Furthermore, in order to adjust the luminance that changes with the aging of the TFT panel 1, the above processing may be performed again after a predetermined time has elapsed.

  According to the liquid crystal display device having the configuration shown in FIG. 8, since the luminance can be adjusted as necessary, the luminance in the TFT panel 500 can always be made uniform, and as a result, the display quality can be improved. Become.

  As described above, in the present embodiment, the example in which the gradation of the input video signal is 8 bits and is pseudo-expanded to 10 bits has been described. However, the present invention is not limited to this. The key may be 10 bits and may be expanded pseudo to 12 bits. In this case, it is possible to realize the subsequent processing by the same processing as when 10-bit expansion is performed only by changing the color gradation expansion circuit 101 in the luminance adjustment circuit 100 shown in FIG. 1 to 12-bit expansion. .

  Further, in the present embodiment, as shown in FIG. 9, the luminance adjustment in the case where the luminance unevenness occurs along the source line (arrow X direction) has been described, but the luminance unevenness occurs in the gate line (arrow Y direction). In the case of occurrence along the line, the luminance unevenness can be eliminated by adjusting the luminance similarly.

  That is, for the uneven stripe in the vertical direction (direction along the source line), the luminance adjustment data may be generated based on the luminance value obtained from the area corresponding to each source line of the liquid crystal display panel. In this case, the same processing may be performed for each source line for each gate line, and correction data (brightness-adjusted video signal) may be output.

  In addition, for horizontal stripes (in the direction along the gate lines), the luminance adjustment data may be generated based on the luminance values obtained from the areas corresponding to the gate lines of the liquid crystal display panel. In this case, correction processing may be performed for each gate line, and the same correction data may be output to the entire source line as a luminance-adjusted video signal.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The liquid crystal display panel can be applied to a display panel in which luminance unevenness may occur in a stripe shape.

(A) shows embodiment of this invention and is a block diagram which shows the principal part structure of a luminance adjustment circuit, (b) is a pseudo gradation process in the luminance adjustment circuit shown in (a). It is a figure explaining. It is a block diagram of the liquid crystal display device which concerns on this Embodiment. FIG. 3 is a block diagram of a timing control circuit provided in the liquid crystal display device shown in FIG. 2. It is a figure which shows the state which stored the data for luminance adjustment in the memory with which the luminance adjustment circuit shown to Fig.1 (a) was equipped. It is a figure explaining the gradation pseudo | simulation expansion process performed in the luminance adjustment circuit shown to Fig.1 (a). It is a figure explaining the other gradation pseudo expansion processes performed in the luminance adjustment circuit shown to Fig.1 (a). It is a flowchart which shows the flow of the production | generation process of the data for brightness adjustment. It is a block diagram which shows the principal part structure of the liquid crystal display device provided with the TFT panel part which has a light-receiving part. It is a schematic plan view of the TFT panel part shown in FIG. FIG. 10 is a cross-sectional view taken along line AA in FIG. 9. It is a figure which shows the relationship between the light receiving element and pixel electrode row | line | column in the TFT panel part shown in FIG.

Explanation of symbols

1 TFT panel (display panel)
2 source drive circuit 3 gate drive circuit 4 timing control circuit 11 chassis 11a bezel 100 brightness adjustment circuit 101 color gradation expansion circuit 102 memory 200 video data correction circuit 300 panel data transmission circuit 400 timing generation circuit 500 TFT panel 500c TFT unit 501 display Area 501a Luminance unevenness 502 Light receiving element 503 Reflecting mirror 600 Video signal processing circuit 601 CPU
602 ROM
603 RAM
604 Interface for writing 605 Image processing LSI
606 Reading interface

Claims (7)

In a luminance adjustment circuit for adjusting the luminance of a video signal input to a display panel capable of displaying m (m: integer of 2 or more) bit gradation,
In order to eliminate the luminance unevenness on the display panel, the relationship n (n: 1 or more and m> n) is set in association with each line of the display panel to which the video signal is input. An integer) bit storage means for storing brightness adjustment data;
The n-bit luminance adjustment data associated with the input line information of the display panel included in the video signal of m-bit gradation is read from the storage means, and the number of gradations of the video signal is (m + L: n ≧ L > 1) Expand to bit, select m-bit gradation determined in advance by the luminance adjustment data from the expanded (m + L) -bit gradation video signal, and display the above as m-bit gradation video signal A luminance adjustment circuit comprising gradation expanding means for outputting to a panel. The gradation extending means is
Read out n-bit brightness adjustment data associated with the input line information of the display panel included in the video signal of m-bit gradation from the storage means, and expand the number of gradations of the video signal to (m + n) bits Then, from the expanded (m + n) -bit gradation video signal, m-bit gradation determined in advance by the luminance adjustment data is selected and output to the display panel as an m-bit gradation video signal. The brightness adjustment circuit according to claim 1, wherein When the display panel is a liquid crystal display panel,
The luminance adjustment circuit according to claim 1, wherein the luminance adjustment data is generated based on a luminance value obtained from an area corresponding to each source line of the liquid crystal display panel. The liquid crystal display panel has
A light receiving element that receives irradiation light from a display area corresponding to each source line;
Brightness adjustment data generation means for generating the brightness adjustment data from the received light data for each source line received by the light receiving element,
4. The brightness adjustment circuit according to claim 3, wherein the storage means stores brightness adjustment data generated by the brightness adjustment data generation means. When the display panel is a liquid crystal display panel,
The brightness adjustment circuit according to claim 1 or 2, wherein the brightness adjustment data is generated based on a brightness value obtained from a region corresponding to each gate line of the liquid crystal display panel. The liquid crystal display panel has
A light receiving element that receives irradiation light from a display area corresponding to each gate line;
Brightness adjustment data generating means for generating the brightness adjustment data from the received light data for each gate line received by the light receiving element;
6. The brightness adjustment circuit according to claim 5, wherein the storage means stores brightness adjustment data generated by the brightness adjustment data generation means. A liquid crystal display panel;
A video processing circuit for supplying a video signal to the liquid crystal display panel;
The brightness adjustment circuit according to any one of claims 1 to 6, which adjusts the brightness of a video signal supplied to the liquid crystal display panel,
The liquid crystal display device, wherein the video processing circuit supplies a video signal whose luminance is adjusted by the luminance adjustment circuit to the liquid crystal display panel.

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