JP4540940B2 - Backlight driving device, display device including the same, liquid crystal television receiver, and backlight driving method. - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a backlight drive device for a display device whose display method is a hold type, a display device including the same, a liquid crystal television receiver, and a backlight drive method.
[0002]
[Prior art]
The liquid crystal display device is superior in size, light weight and low power consumption compared with the CRT, and is taking the leading role in the display device from the CRT. In the display method, the liquid crystal display device is a hold type, whereas the CRT is an impulse type.
[0003]
In an impulse type CRT, an electron beam is made to collide with a phosphor screen to emit light, and each point on the screen is displayed only for a very short time consisting of phosphor afterglow. In the CRT, this point emission is sequentially scanned to display one frame image using the afterimage effect of the eyes.
[0004]
On the other hand, in a hold-type liquid crystal display device, display data is written once per frame using data signal lines and scanning signal lines to pixels arranged in a matrix. The written display data is held for one frame in each pixel.
[0005]
In the liquid crystal display device, the moving image display performance is inferior to that of the CRT due to the above-described difference in display method from the CRT. This point is described in detail in, for example, “Hold Display Display Method and Image Quality in Video Display” (Yasuhiro Kurita, Liquid Crystal Society, 1st LCD Forum Proceedings Issued on August 28, 1998) .
[0006]
That is, in the CRT, since the phosphor (screen) only shines instantaneously for each field (for example, every 16.7 msec), a moving image is made smooth by using the afterimage effect for human eyes. It will be reflected. On the other hand, in the liquid crystal display device, in the case of the transmissive type, the backlight is always lit, so that the pixels in which the bright display data is written are based on the same bright display data for one field period (for example, 16.7 msec period). The light is displayed. Accordingly, the moving image appears as a blurred image to the human eye. This problem cannot be solved by increasing the response speed of the liquid crystal display device.
[0007]
Therefore, for example, in Japanese Patent Application Laid-Open No. 2001-318614 (first prior art), by repeating the blinking of the backlight in the period of vertical synchronization, impulses are realized also in the liquid crystal display device, and the moving image display performance is improved. Technology has been proposed.
[0008]
In this case, the liquid crystal display device performs line sequential scanning, and one period thereof coincides with the period of vertical synchronization. That is, if the backlight is simply blinked, the lighting timing in the blinking of the backlight and the signal writing timing to the pixel differ depending on the location, leading to deterioration of display quality such as generation of pseudo contour.
[0009]
Therefore, in this publication, in order to eliminate the timing discrepancy between the two, a plurality of cold-cathode tubes of the direct type backlight are sequentially blinked sequentially, and the backlight itself is scanned in accordance with the line sequential scanning of the liquid crystal display device. Thus, the lighting timing in the flashing of the backlight and the signal writing timing to the pixel are made to coincide with each other.
[0010]
Japanese Patent Laid-Open No. 2002-287700 (second prior art) discloses that, similarly to the first prior art, lighting of the backlight in one field is performed in order to prevent a decrease in moving image display performance due to constant lighting of the backlight. Techniques that limit time have been proposed. Specifically, by shortening the signal writing time, the display signal is written to the data signal line with the backlight turned off in the first half of the vertical synchronization, and the backlight is turned on in the second half after the writing of the display signal is completed. A technique of lighting is proposed.
[0011]
[Patent Document 1]
JP 2001-318614 A (publication date November 10, 2001)
[0012]
[Patent Document 2]
JP 2002-287700 A (publication date October 4, 2002)
[0013]
[Patent Document 3]
JP-A-6-62355 (publication date March 4, 1994)
[0014]
[Non-Patent Document 1]
Kurita, Yasushiichi “Hold-type display and video quality” The Liquid Crystal Society of Japan, Proceedings of the 1st LCD Forum August 28, 1998
[0015]
[Problems to be solved by the invention]
However, the first prior art has a problem that brightness unevenness occurs first. That is, in the first prior art, among the plurality of fluorescent lamps constituting the backlight, the light of the fluorescent lamp to be lit is not radiated to the pixels other than the pixel corresponding to the fluorescent lamp, between the individual fluorescent lamps. It is necessary to provide a partition plate. However, when this partition plate is reflected on the screen, luminance unevenness occurs. As a result, new problems such as an increase in the number of parts and display unevenness (luminance unevenness) are caused.
[0016]
Note that, for example, when a scattering sheet is added in order to reduce the luminance unevenness, light wraps around to other areas beyond the partition plate, and the effect of providing the partition plate is reduced. As a result, the moving image display performance is deteriorated, and a desired performance cannot be obtained by providing the partition plate.
[0017]
Second, in order to independently control the blinking of each fluorescent lamp, an inverter circuit and a pulse light emitting circuit corresponding to the number of fluorescent lamps are required. As a result, the circuit configuration is complicated and the cost is increased.
[0018]
Thirdly, in principle, the backlight is limited to a direct type, which requires a small number of lamps, and causes an inconvenience that an edge light type used in a small and medium-sized liquid crystal display cannot be applied.
[0019]
On the other hand, in the second conventional technique, the signal writing period is shortened as compared with the configuration in which the display signal is written to each pixel using one field period. It is necessary to shorten the signal writing time. However, when the writing time is simply shortened, signal writing to each pixel is insufficient, that is, charging is poor, and the display quality is deteriorated. In order to prevent this, it is necessary to modify all the electrical characteristics of the data signal line, the scanning signal line, and the TFT.
[0020]
In addition, since the data signal line and the gate signal line have signal delay due to electric resistance and capacitance, it is practically difficult to shorten the writing time. This is particularly disadvantageous for large liquid crystal display devices and HDTV liquid crystal display devices having a large number of pixels.
[0021]
In addition, in order to shorten the time for writing the display signal to the pixel, it is necessary to reduce the on-resistance of the TFT which is a switching element. In this case, it is necessary to increase the size of the TFT, and as a result, the aperture ratio (transmittance) decreases.
[0022]
Therefore, the liquid crystal display device of the present invention has a backlight driving device that can display a moving image with high quality while suppressing luminance unevenness and cost increase, a display device including the same, a liquid crystal television receiver, and a backlight driving device. The purpose is to provide a method.
[0027]
[Means for Solving the Problems]
  The backlight driving device of the present invention has a plurality of scanning lines arranged in one direction, and these scanning lines are sequentially scanned to drive a backlight of a display panel in which a display signal is written to a pixel corresponding to each scanning line. In the backlight driving device, the display area of the display panel is divided into a plurality of blocks with a plurality of adjacent scanning line groups as one block, and the moving image for each block in the image of one vertical period input to the display panel A moving image detecting means for detecting the presence or absence of the image, a contour steep image detecting means for detecting the presence or absence of an image having a steep outline for each block in the image of one vertical period input to the display panel, and the moving image detecting means. One vertical of a moving image existence block which is a block including an image detected as a moving image and detected as a contour steep image by the contour steep image detecting means. Depending on the occurrence state between, it is characterized by comprising a backlight control means for adjusting the waveform and phase of the drive voltage of the backlight within a single vertical period.
[0028]
  In addition, the backlight driving method of the present invention has a plurality of scanning lines arranged in one direction, and the scanning lines are sequentially scanned, and a display signal is written to pixels corresponding to the scanning lines. In the method, the display area of the display panel is divided into a plurality of blocks with a plurality of adjacent scanning line groups as one block, and whether or not there is a moving image for each block in an image of one vertical period input to the display panel. A first step of detecting, a second step of detecting the presence or absence of an image having a steep outline for each block in an image of one vertical period input to the display panel, and a moving image in the first step According to the appearance state in one vertical period of the moving image existence block, which is a block that includes the image detected and detected as the contour steep image in the second step, Adjusting the waveform and phase of the drive voltage of the backlight in a vertical periodThird stepIt is characterized by having.
[0029]
According to the above configuration, the backlight control unit performs backlighting in one vertical period according to the appearance state in one vertical period of a moving image existence block that is a block including an image that is a moving image and a sharp contour image. The waveform and phase of the driving voltage are adjusted.
[0030]
As described above, in the configuration in which the display area of the display panel is divided into a plurality of blocks and the presence or absence of an image that is a moving image and a sharp contour image is detected for each block, for example, the image is included in a part of an image in one vertical period. In such a case, it is possible to appropriately cope with displaying the image with high quality. That is, according to various appearance states in one vertical period of the moving image existence block, it is possible to control the lighting of the backlight to an optimum state for suppressing, for example, luminance unevenness. High quality can be done. The processing as described above is, for example, control of the lighting timing and lighting period of the backlight, so that complicated circuits and components are not required and can be performed at low cost.
[0031]
Furthermore, since the lighting of the backlight is controlled not according to the appearance state of the moving image existence block including the moving image but according to the appearance state of the moving image existence block including the image that is the moving image and the contour sharp image, it is displayed truly. It is possible to control the lighting of the backlight corresponding to the block whose quality can be improved. Accordingly, it is possible to prevent a situation where useless lighting control is performed and a situation where the display quality of a moving image is not improved without performing lighting control that should be originally performed.
[0032]
For example, if the shutter speed at the time of shooting is slow even for a moving image, the effect of performing backlight lighting control, for example, impulse conversion, according to the appearance state of the moving image existence block including the moving image is small.
[0033]
On the other hand, images with fast shutter speeds at the time of shooting have steep outlines (edges) even if they are moving images, and backlight lighting control, for example, impulse generation, according to the appearance state of moving image existence blocks including such moving images Performing this has a great effect of improving the display quality of moving images. For example, if the title telop scrolls left and right in the lower part of the screen and the background is also a moving image, only the lower part of the screen has the effect of impulse. Therefore, the configuration of the present invention is effective in improving the display quality of a character image (for example, title telop) that scrolls to the left and right of the screen, for example.
[0034]
In the above backlight drive device, the moving image detection means detects the presence or absence of a moving image by comparing the total value of the number of moving image pixels included in each block with a threshold value, and the threshold value is the total value of the number of moving image pixels. It is good also as a structure changed according to the total value of the moving image pixel number in the block in which becomes the maximum value.
[0035]
According to the above configuration, the threshold for detecting the presence or absence of a moving image is changed according to the total number of moving image pixels in the block in which the total number of moving image pixels is the maximum value. Even if the moving image present in the screen is small, the moving image can be detected appropriately, and the display quality of the moving image can be improved.
[0036]
In the above backlight drive device, the moving image detection means sets the threshold to 1 / n 2 of the total number of moving image pixels in the block in which the total value of moving image pixels is the maximum (n is a positive value). It is good also as a structure set to the value of an integer.
[0037]
According to the above configuration, the moving image detection unit has a very simple logic and can simplify the circuit configuration.
[0038]
In the above backlight driving device, the backlight control means turns on the backlight from a timing when a response for display by writing display data to the moving image existence block, for example, a response of the display element is almost completed. It is good also as a structure adjusted as follows.
[0039]
According to the above configuration, the backlight is turned on from the timing when the response for display by writing the display data to the moving image existence block is almost completed, so that occurrence of uneven brightness can be prevented.
[0040]
In the above-described backlight driving device, the backlight control unit may be configured to adjust so that the backlight is turned off at a timing when writing of display data to the moving image existence block is started.
[0041]
According to the above configuration, since the backlight is turned off at the timing when writing of display data to the moving image existence block is started, it is possible to prevent occurrence of luminance unevenness.
[0042]
In the backlight drive device described above, the moving image existence block may be configured such that only one block among all the blocks is a moving image existence block.
[0043]
According to the above configuration, when only one block out of all blocks is a moving image existence block, the backlight is turned on with respect to the moving image existence block, for example, when the response of the display element is almost completed. Appropriate adjustment can be performed, and the display device can be appropriately impulsed with respect to the appearance state of such a moving image existence block.
[0044]
In the backlight drive device described above, the moving image existence block may be configured such that a plurality of blocks among all the blocks are moving image existence blocks and they are continuous.
[0045]
According to the above configuration, when a plurality of blocks among all the blocks are moving image existence blocks and they are continuous, for example, back-up from the timing when the response of the display element is almost completed with respect to the moving image existence blocks. The light can be appropriately adjusted so as to be turned on, and the display device can be appropriately impulsed with respect to the appearance state of such a moving image existence block.
[0046]
In the backlight drive device described above, the backlight control unit may be configured to adjust so that the backlight is always lit when none of the blocks is a moving image existence block.
[0047]
In the above backlight driving device, the backlight control unit may be configured to adjust the flashing frequency of the backlight to be high when none of the blocks is a moving image existence block.
[0048]
According to the above configuration, all the images in one vertical period are still images, and in this case, the blinking frequency of the backlight is increased, so that the occurrence of flicker can be suppressed. The degree of increasing the lighting frequency is preferably at least twice the vertical synchronization frequency, and more preferably about four times.
[0049]
For example, when there is only one moving image existence block, the integrated luminance is reduced when the backlight is turned on and the display device is impulsed only in one part of one vertical period. Therefore, in order to match the integrated luminance at this time with the integrated luminance at the time of a still image, when all the images in one vertical period are still images, the lighting period of one backlight is shortened, and the backlight Increase the pulse frequency. For example, it blinks at 240 Hz. Thereby, hold mode display is performed on the display device.
[0050]
In the backlight drive device described above, the backlight control unit may be configured to adjust so that the backlight is always lit when all the blocks are moving image existing blocks.
[0051]
According to the above configuration, since all the blocks are moving image existing blocks, the backlight is always turned on, so that it is possible to suppress the occurrence of pseudo contours. That is, when all the blocks are moving image existing blocks, it is impossible to impulse the display device by controlling the lighting of the backlight. Therefore, the backlight is turned on for one vertical period, and the display device is displayed by the hold method.
[0052]
In the above backlight driving device, the backlight control unit may be configured to adjust the flashing frequency of the backlight to be high when all the blocks are moving image existing blocks.
[0053]
According to the above configuration, all the images in one vertical period are moving images, and in this case, the blinking frequency of the backlight is increased, so that occurrence of flicker can be suppressed. The degree of increasing the lighting frequency is preferably at least twice the vertical synchronization frequency, and more preferably about four times.
[0054]
For example, when there is only one moving image existence block, the integrated luminance is reduced when the backlight is turned on and the display device is impulsed only in one part of one vertical period. Therefore, in order to match this integrated luminance with the integrated luminance when all the blocks are moving image existing blocks, when all the blocks are moving image existing blocks, the lighting period of one backlight is shortened, and Increase the pulse frequency of the backlight. For example, it blinks at 240 Hz. Thereby, hold mode display is performed on the display device.
[0055]
In the backlight drive device described above, the backlight control unit may be configured to adjust so that the backlight is always lit when a plurality of discontinuous blocks are moving image existing blocks.
[0056]
According to the above configuration, when a plurality of non-consecutive blocks are moving image existing blocks, the backlight is always lit. Therefore, the display device is impulsed by controlling the lighting of the backlight according to any moving image existing block. It is possible to prevent the occurrence of a pseudo contour due to this. Further, it is preferable to increase the brightness of the screen by always lighting the backlight.
[0057]
In the above backlight drive device, the backlight control unit may be configured to adjust the flashing frequency of the backlight to be high when a plurality of non-continuous blocks are moving image existing blocks.
[0058]
According to said structure, since the blinking frequency of a backlight becomes high, generation | occurrence | production of flicker can be suppressed.
[0059]
In the above backlight driving device, the backlight control unit may be configured to display the backlight in one vertical period when the same appearance state occurs in a plurality of vertical periods with respect to the appearance state in one vertical period of the moving image existence block. It is also possible to adjust the waveform and phase of the drive voltage.
[0060]
According to said structure, since the change of the lighting state with a back line is performed gently, the situation where the lighting state of a backlight is changed frequently and it is recognized as flickering of a screen can be suppressed.
[0061]
In the above backlight drive device, the moving image detecting means may be configured to detect the presence or absence of a moving image for each block by comparing the image signal of the current frame with the image signal of the frame immediately before the current frame. .
[0062]
According to the above configuration, it is possible to cope with a progressive display device.
[0063]
In the above backlight driving device, the moving image detecting means may be configured to detect the presence or absence of a moving image for each block by comparing the image signal of the current field with the image signal of the field immediately preceding the current field. .
[0064]
According to the above configuration, it is possible to deal with an interlace display device. In the interlace method, the current field pixel and the previous field pixel correspond to each other, so that the presence or absence of a moving image can be accurately detected.
[0065]
In the above backlight driving device, the moving image detecting means may be configured to detect the presence / absence of a moving image for each block by comparing an image signal of the current field with an image signal of a field immediately preceding the current field. .
[0066]
According to the above configuration, for example, in an interlace display device, it is also possible to detect the presence or absence of a moving image for each block by comparing the image signal of the current field with the image signal of the field immediately before the current field. In this case, the storage capacity required for the image memory can be halved compared with the case where the image signal of the current field is compared with the image signal of the field immediately before the current field.
[0067]
In the above backlight drive device, the moving image detecting unit calculates a difference in gradation data for each pixel of the image signal to be compared, and calculates the total value of the moving image pixels whose difference is larger than the first threshold value as the second value. It is good also as a structure which detects the presence or absence of a moving image by comparing with this threshold value.
[0068]
According to the above configuration, the moving image detection unit can be configured by adding a few logic circuits to the OS drive, which is the same as the configuration in which the number of pixels in which the OS is turned on in the OS drive is counted.
[0069]
In the above backlight drive device, the steep outline image detecting means may be configured to detect a character image.
[0070]
According to the above configuration, for example, for an image in which a character scroll image (for example, a title telop) is added as a moving image to a previously captured image, the character scroll image is appropriately detected as a moving image, and the display quality is determined. Can be improved.
[0071]
A display device according to the present invention includes any one of the backlight driving devices described above.
[0072]
The above display device detects a moving picture pixel based on a comparison result of the comparison circuit of the comparison circuit that compares the gradation data of the pixel to detect the moving picture, and performs a display response to the moving picture pixel at high speed. A display speed-up circuit having a signal correction circuit that performs signal correction to make the video correction, and the moving picture detection means detects the presence or absence of a moving picture by using the comparison result in the comparison circuit in the display speed-up circuit. Also good.
[0073]
According to the above configuration, the moving image detection unit uses the comparison result in the comparison circuit in the known display speed-up circuit provided in the liquid crystal display device, for example, so that the configuration can be simplified.
[0074]
The liquid crystal television receiver of the present invention has a configuration including any of the display devices described above.
[0075]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram of the liquid crystal display device of this embodiment. As shown in the figure, the liquid crystal display device includes a liquid crystal panel (display panel) 1, a source driver 2, a gate driver 3, an LCD controller 4, an image memory 5, a comparison circuit (moving image detection means) 6, a comparison result storage circuit ( (Moving image detecting means) 7, BL waveform control circuit (moving image detecting means, backlight control means) 8, inverter circuit 9 and backlight 10.
[0076]
The liquid crystal panel 1 is provided, for example, such that a plurality of source signal lines arranged in the vertical direction of the screen and a plurality of gate signal lines arranged in the horizontal direction intersect, and are active elements at the intersections. An active matrix type having a TFT. In the present embodiment, the number of pixels is, for example, 640 * 480 * RGB (VGA).
[0077]
The source driver 2 supplies a display signal to each of the source lines. The gate driver 3 operates so that a display signal is written to each pixel by sequentially selecting the above-described gate signal lines and sequentially turning on the TFTs. The LCD controller 4 controls the operations of the source driver 2 and the gate driver 3.
[0078]
The image memory 5 stores one screen of a video signal (image signal) before one vertical synchronization. One screen corresponds to one field in the interlace method and one frame in the progressive method. In the following description, the one vertical period is described simply as 1f as appropriate. In the present embodiment, the input video signal is, for example, a progressive digital signal having 480 scanning lines. The vertical frequency (frame frequency) of the signal is 60 Hz.
[0079]
The comparison circuit 6 compares the current video signal for each pixel with the video signal before one vertical synchronization stored in the image memory 5 (hereinafter referred to as the previous video signal). Which one is determined. Here, the difference between signals (digital signal values indicating gradation numbers from 0 to 255) as the threshold A (first threshold) is, for example, 8, and the difference between the current video signal and the previous video signal exceeds 8. Whether or not there is a pixel unit. When the difference exceeds 8, the pixel is determined as a moving image pixel, and when the difference is less than 8, the pixel is determined as a still image pixel. Here, the RGB signals are compared separately, and if the difference of at least one of these three signals exceeds the threshold A, the pixel is determined as a moving image pixel.
[0080]
Further, the value of 8 in the threshold A is not limited to this and is preferably adjusted as appropriate. That is, when the noise component is small in the input video signal, the threshold value A can be set smaller. On the other hand, if there are many noise components, the signal difference may be large even in the case of a still image, resulting in an erroneous determination. Therefore, the threshold A is set larger. In addition, for example, when the radio wave condition is bad, in the case of analog video, in the case of a video signal for a game, or in the case of a DVD video signal, the magnitude of noise differs depending on the video signal source. Therefore, the threshold A is preferably set as appropriate according to the video signal source.
[0081]
As shown in FIG. 2, the comparison result storage circuit 7 divides the screen into 5 blocks in the arrangement direction of the gate signal lines, and counts the number of pixels exceeding the threshold A for each block.
[0082]
The BL waveform control circuit 8 checks the count value C of the number of pixels exceeding the threshold A for each block stored in the comparison result storage circuit 7, and the block where the count value C exceeds the threshold B (second threshold). Is detected, and it is determined that the moving image object is included in the block. Here, the threshold value B is set to 3072, for example. This value is determined as (640 * 480 / number of blocks 5) * 5%. Note that the value of the threshold B is not limited to this, and may be other values or not a fixed value. For example, the threshold value B is preferably set to a half of the count value in the block having the maximum count value C. In addition, it is preferable to set the count value in the block having the maximum count value C to 1 / th power of 2.sup.n. By doing in this way, the structure for detecting the presence or absence of the moving image in the BL waveform control circuit 8 can be simplified.
[0083]
Further, the BL waveform control circuit 8 determines whether or not there is a block whose count value C exceeds the threshold B (hereinafter referred to as a moving image existence block) and the detection state (appearance state) of the moving image existence block, for example, the number of detected moving image existence blocks ( The phase of the input voltage to the inverter circuit 9 is controlled according to the number of occurrences) or the detection position (appearance position) of the moving image existence block.
[0084]
The inverter circuit 9 supplies drive voltage to the backlight 10 to turn on and off the backlight 10. The backlight 10 illuminates the liquid crystal panel 1 from the back side. In the present embodiment, even if the backlight 10 is composed of, for example, a plurality of fluorescent tubes, they are driven so as to be turned on simultaneously and turned off simultaneously.
[0085]
In the above configuration, the video signal input to the liquid crystal display device is supplied to the LCD controller 4 and the comparison circuit 6. The LCD controller 4 controls the source driver 2 and the gate driver 3 based on the input video signal. As a result, a display signal is given from the source driver 2 to the source signal line of the liquid crystal panel 1, and the gate driver 3 scans each gate signal line of the liquid crystal panel 1, whereby the display signal is written to each pixel. An image of the input video signal is displayed on the panel 1.
[0086]
On the other hand, each means from the image memory 5 to the backlight 10 performs the following operation. The operation will be described below using the flowchart of FIG.
[0087]
The comparison circuit 6 compares the input current video signal and the video signal before one vertical synchronization stored in the image memory 5 in units of pixels (S1), and whether the difference between both video signals exceeds the threshold A or not. It is determined whether or not (S2), and the determination result is given to the comparison result storage circuit 7.
[0088]
The comparison result storage circuit 7 counts the number of pixels exceeding the threshold A (A = 8) for each of the first to fifth blocks (S3). The above processing is performed for all the pixels of the liquid crystal panel 1 (S4).
[0089]
As a result of the above counting, the number of pixels exceeding the threshold A for each block is, for example, as shown in FIG.
[0090]
In the BL waveform control circuit 8, the count value C of the number of pixels exceeding the threshold A for each block stored in the comparison result storage circuit 7 is checked, and the block where the count value C exceeds the threshold B (B = 3072), that is, A moving image existence block is detected, and it is determined that a large moving image exists in the block (S5).
[0091]
Further, the BL waveform control circuit 8 controls the input voltage waveform and the phase to the inverter circuit 9 according to the appearance state of the moving image existence block, that is, the presence / absence of the moving image existence block, the number of occurrence and the appearance position, etc. S6).
[0092]
In the example of FIG. 4, only the count value C of the fifth block exceeds the threshold B, and the BL waveform control circuit 8 determines that only the fifth block is a moving image existence block in which a large moving image object exists. Thus, a state where a moving image existence block is detected (a state where a large moving image object exists in the block) frequently occurs. A typical example is a scroll video such as the name of a program staff or the name of a sponsoring company that flows at the end of a television program. In many cases, this scroll image is displayed so as to flow at high speed from right to left at the bottom of the screen, and is a clear character image. Therefore, the conventional liquid crystal display device has been noticeably blurred.
[0093]
Therefore, when only one block is a moving image existence block as shown in FIG. 4, the BL waveform control circuit 8 adjusts the input voltage waveform of the inverter circuit 9 as shown in FIG. In this case, the backlight 10 is lit only when the pulse waveform is at a high level. That is, in the example of FIG. 5, the input voltage waveform to the inverter circuit 9 is a pulse waveform in which, for example, 40% of one vertical period is a light emission period (a part of one vertical period is an issuance period). The phase of the pulse waveform is adjusted so that the falling edge of the pulse waveform is immediately before the signal is written to the fifth block. As a result, the backlight 10 does not emit light during the period in which the display signal is written to the pixels of the block 5 and the period in which the liquid crystal is responding thereto. As a result, the generation of the pseudo contour is eliminated and the moving image display quality is improved.
[0094]
Since the first to fourth blocks other than the fifth block are still images, the display quality in these blocks is whether the backlight 10 is turned on or off at the timing of writing the display signal to these blocks. It is hard to be influenced depending on.
[0095]
Further, the light emission period of the backlight 10 in one vertical period when the moving image existence block exists is not limited to the above 40%. For example, if only considering improving the display quality of moving images, the shorter the light emission period, the better. However, if the time is excessively short, the screen becomes too dark. Therefore, if securing the luminance of the liquid crystal panel 1 is also taken into consideration, it is preferable to set it to 40-50%. This also applies to the other examples below.
[0096]
Further, in the present embodiment, the lighting period of the backlight 10 is only one period in one vertical period. By doing so, the generation of a pseudo contour is prevented.
[0097]
The writing period to each block is a period obtained by dividing approximately one vertical period by the number of blocks when the number of scanning lines included in each block is the same.
[0098]
In the example of FIG. 6, the count value C is equal to or less than the threshold value B in all blocks. In this case, the BL waveform control circuit 8 determines that all the blocks are not moving image existence blocks, and performs the following control on the inverter circuit 9. In addition, the count value C is equal to or less than the threshold value B in all the blocks as described above when the video of all the blocks can be regarded as a still image.
[0099]
In this case, even if the BL waveform control circuit 8 controls the input voltage waveform (lighting of the backlight 10) to the inverter circuit 9 as shown in FIG. 5, the display quality of the liquid crystal panel 1 is not greatly affected. However, in order to obtain higher display quality, the input voltage waveform to the inverter circuit 9 is preferably the waveform shown in FIG.
[0100]
In the waveform shown in FIG. 7, the integrated value is the same as that in FIG. 5, but the frequency is changed from 60 Hz to 240 Hz. Thereby, flicker can be suppressed and the integrated luminance in the case of a still image can be made the same as the integrated luminance in the case where a moving image existence block exists (FIGS. 4 and 5). Of course, the backlight 10 may be always turned on and the integrated luminance may be the same as in the case of FIG.
[0101]
Furthermore, it is possible to increase the brightness of the still image by turning on the backlight 10 at all times with high brightness. Although it is difficult to obtain a peak luminance unlike a CRT in a liquid crystal display device, by setting the backlight 10 to a different luminance for a moving image and a still image, that is, by always turning on the backlight 10 during a still image, The vividness like this will be obtained.
[0102]
In the example of FIG. 8, two adjacent blocks, that is, the fourth and fifth blocks exceed the threshold value B. Therefore, the BL waveform control circuit 8 determines that the fourth and fifth blocks are moving image existence blocks.
[0103]
When the two consecutive blocks are moving image existence blocks, the BL waveform control circuit 8 changes the phase of the pulse waveform of the input voltage to the inverter circuit 9 as shown in FIG. Is adjusted to be immediately before signal writing to the pixels of the fourth block in the upper order in the scanning order by the gate driver 3. In this case, the time from when a signal is written to the pixels in the last row of the fifth block until the backlight 10 is activated is shortened from 2/5 field to 1/5 field. There was no problem with the quality.
[0104]
In the example of FIG. 10, two discontinuous blocks, that is, the second block and the fifth block exceed the threshold value B. In the example of FIG. 11, all the blocks exceed the threshold value B.
[0105]
As described above, when a plurality of non-continuous blocks are moving image existence blocks, and when all the blocks are moving image existence blocks, the BL waveform control circuit 8 determines that the moving image existence block corresponds to the input voltage to the inverter circuit 9. The same control as that in the case where it does not exist (when all the blocks are still images) is performed. That is, the BL waveform control circuit 8 assumes that the input voltage waveform to the inverter circuit 9 is as shown in FIG.
[0106]
In this case, although the effect of making the display of the liquid crystal display device impulse is lost, the pseudo contour due to improper timing between the blinking of the backlight 10 and the liquid crystal response does not occur. FIG. 12A shows an example in which the timing of the flashing of the backlight 10 and the liquid crystal response is appropriate (when the response completion time of the liquid crystal and the rise of the inverter input waveform substantially match), and FIG. ) Shows an example in which the same timing is inappropriate (when the response completion time of the liquid crystal and the rising edge of the inverter input waveform are greatly deviated).
[0107]
In addition, as a result of examining the various images by the inventors of the present application, the improvement of the moving image display quality by blinking the backlight 10 is obtained in any image even if both the above timings are appropriate. I understood that it was not limited. The reason is the video shooting conditions.
[0108]
For example, when the shutter speed of the camera when shooting a video is 1/60 sec (open state), the subject is moving and blurred. Therefore, no matter how much the blinking of the backlight 10 is controlled (impulsed) with respect to the originally blurred video, a significant improvement in display quality cannot be expected. On the other hand, since the above-described scroll video combines character information with a real video, the characters themselves are not blurred at all. In such a case, it has been found that the effect of improving the display quality of the moving image by controlling the blinking of the backlight 10 (impulsed) is extremely large.
[0109]
Accordingly, in the moving movie as a whole, the count value C becomes as shown in FIG. 11, and as a result, the shutter speed is 1/60 sec even when the impulse (flashing control of the backlight 10) is stopped. If there is, the display quality is hardly affected.
[0110]
In the above example, as shown in FIG. 2, all the pixels of the liquid crystal panel 1 are divided into five blocks in the scanning direction by the gate driver 3, but the number of divisions is limited to this. It may be set appropriately. For example, the number may be increased or decreased within a range of 5 to 10 according to the number of scanning lines. The number of divisions is preferably an odd number when a moving image is often displayed in the middle of the screen, and one block is preferably set in the middle of the screen.
[0111]
FIG. 13 shows a liquid crystal display device provided with an edge detection circuit (outline steep image detection means) 11 in addition to the configuration of FIG. In this liquid crystal display device, the BL waveform control circuit 8 determines a moving image existence block, that is, a block in which the count number C, which is the number of pixels exceeding the threshold A, exceeds the threshold B, and an edge detection circuit Only the block in which the presence of the edge is detected in 11 is determined as a true moving image existence block. Based on the determination result of the moving image existence block, the BL waveform control circuit 8 performs the above-described control on the input voltage to the inverter circuit 9, that is, the lighting control of the backlight 10.
[0112]
The edge detection circuit 11 is used for character recognition, for example, and has a conventionally known configuration for detecting the presence of an edge in an image. The edge detection circuit 11 detects an edge by comparing data in the current video signal.
[0113]
Here, specific examples of the edge detection method and the character recognition method will be described. (Example of edge detection)
Examples of the edge detection method include a method of calculating a primary difference and a secondary difference between adjacent pixels such as up and down, left and right, and diagonal, and a method of performing a Laplacian calculation. Furthermore, if the points extracted by these methods are in a group that is continuous in one of the two-dimensional directions (any direction), it can be determined that the edge (contour) of the object has been detected. it can.
[0114]
Note that edge detection is weak against the noise of the video signal, and even the noise component is detected as an edge. Therefore, it is desirable to apply a noise removal filter that smoothes the signal in advance as preprocessing. However, since it degrades to the actual edge, it is necessary to keep the filtering process to a minimum.
(Character recognition method example)
The title telop is often at or above a specific luminance or below a specific luminance. Therefore, for each of R, G, and B of the video signal, an image is created by extracting points equal to or higher than Eth1 and points equal to or lower than Eth2 with respect to two predetermined threshold values (Eth1, Eth2). The edge detection is performed on this image. The character portion has a high possibility that the edge is formed in a linear shape, and a portion where the edge detection portions are continuous is extracted in a two-dimensional direction (any direction). Character recognition can be performed by searching for a character from the image of only the edge extracted in this way.
[0115]
Needless to say, the same effect can be obtained even if the edge detection method and the character recognition method are performed by methods other than those described above.
[0116]
In this liquid crystal display device, by adding the condition of the presence of an edge in the video in the block to the determination of the moving image existence block, the control is performed only for the block for which the lighting control of the backlight 10 is effective. I have to. This eliminates unnecessary operations, reduces the burden on each circuit, and prevents a decrease in response speed.
[0117]
Here, as described above, the moving image image in which the lighting control of the backlight 10 by the BL waveform control circuit 8 is effective is drawn by, for example, a scroll image such as a character telop flowing left and right at the bottom of the display screen, or computer graphics. This is a video. The scroll image is added to a previously captured image later.
[0118]
On the other hand, a moving image for which lighting control of the backlight 10 is not effective is a video that is originally blurred at the time of being captured by the camera. An example of such an image is an image of a marathon taken, for example. In this video, since the camera is following the runner, the runner is almost a still image and a clear video, but the background video that is a moving image is blurred.
[0119]
Furthermore, for example, as shown in FIG. 14, for example, a video image of an airplane photographed in advance is present in the second block, and a scroll image of characters added later is present in the fifth block. The advantages of this liquid crystal display device will be described.
[0120]
For example, when the video is displayed on the liquid crystal display device shown in FIG. 1, both the airplane and the characters are determined to be moving images. Therefore, the second block and the fifth block are determined to be moving image existence blocks, and as a result, the lighting control of the backlight 10 for the video signal is performed as a still image as in the case shown in FIG. . As a result, the scroll image of the characters in the fifth block becomes blurred and high-quality display cannot be performed.
[0121]
On the other hand, when the video is displayed on the liquid crystal display device shown in FIG. 13, only the characters are determined as moving images. Therefore, only the fifth block is determined to be a moving image existence block, and as a result, the lighting control of the backlight 10 for the video signal is controlled as a moving image as in the case shown in FIGS. 4 and 5. Thereby, a high-definition moving image display can be performed about the scroll image of the character of the 5th block. It should be noted that since the moving image video of the airplane is originally not effective for lighting control for moving images, the above-described lighting control is not particularly affected.
[0122]
FIG. 15 shows an example in which the liquid crystal display device shown in FIG. 1 can be configured easily and at low cost by using a conventionally known liquid crystal speed-up circuit 12. The liquid crystal speed-up circuit 12 includes a comparison circuit 12a corresponding to the comparison circuit 6 and a signal correction circuit 12b. If the configuration of the liquid crystal acceleration circuit 12 is shown in a simple block diagram, it will be as shown in FIG.
[0123]
Similar to the comparison circuit 6, the comparison circuit 12b performs comparison for detecting moving image pixels. In the lighting control of the backlight 10, the comparison result in the comparison circuit 12a is used.
[0124]
The liquid crystal speed-up circuit 12 includes a look-up table, and a look-up table for an input value of 128, for example, in order to speed up the response to a pixel determined as a moving image pixel as a result of comparison in the comparison circuit 12a. Referring to FIG. 4, an overshoot value of, for example, 160 is given for the period of 1f. As a result, as shown in FIG. 16B, a response with a high-speed response waveform is performed with respect to the normal response waveform.
[0125]
The liquid crystal acceleration circuit 12 is described in detail in, for example, Japanese Patent Laid-Open No. 6-62355.
[0126]
As described above, in the liquid crystal display device according to the present embodiment, the screen is divided into a plurality of blocks with a plurality of adjacent gate signal line groups as one block, and the lighting period of the backlight 10 is shorter than one vertical period. When the moving image existence block is included in the plurality of blocks, the lighting period is set to end in the block immediately before the moving image existence block in the scanning direction of the gate signal line. Thereby, the display quality of the moving image included in the image | video of 1 vertical period can be improved, suppressing generation | occurrence | production of a pseudo contour. This function will be described in more detail below.
[0127]
FIG. 17 shows a relationship between an input voltage waveform (lighting timing of the backlight 10) to the inverter circuit 9 and a liquid crystal response waveform by signal writing corresponding to the cases shown in FIGS. In the figure, the lighting period of the backlight 10 ends in the block immediately before the moving image existence block, and the completion timing of the liquid crystal response by the signal writing to the fifth block matches the lighting timing of the backlight 10. Yes. Therefore, it is possible to improve the display quality of the moving image included in the video of one vertical period while suppressing the generation of the pseudo contour.
[0128]
As described above, the lighting period of the backlight 10 is best terminated in the block immediately before the moving image existence block, but is not limited thereto. Although the function of suppressing the pseudo contour is reduced, for example, even when the period of the second and third blocks that are still images is set as the lighting period of the backlight 10, the moving image display quality of the fifth block (moving image existing block) is improved. be able to.
[0129]
That is, it is the worst state in which the lighting period of the backlight 10 coincides with the signal writing period to the moving image existence block (scanning period of the moving image existence block). If this is avoided, the moving image display quality is at least higher than the worst state. Can be improved. In addition, it is possible to set the lighting timing of the backlight 10 that is acceptable as display quality from the relationship between the number of divided blocks (scanning period of each block) and the lighting period of the backlight 10.
[0130]
In the above embodiment, the moving image is detected by comparing pixel gradations. However, the present invention is not limited to this, and other well-known methods such as MPEG (Motion Picture Experts Group) can be used. It can also be done using technology. For example, instead of the image memory 5 and the comparison circuit 6, a motion picture may be detected by using a motion detection technique of an MPEG decoder.
[0131]
If the video signal is originally MPEG, a motion vector that is a part of the video signal can be used. Since the motion detection technology based on MPEG can detect the intensity of motion due to the magnitude of the motion vector, it is also possible to match the lighting timing of the backlight to a location where the motion is particularly intense, and the effect of the invention can be maximized. .
[0132]
Further, for example, in the second prior art described above, the motion amount of the entire screen is detected to detect whether the entire image is a moving image or a still image, whereas in the configuration of the present embodiment, the moving image image is divided for each block. Whether or not is included is determined. Therefore, in the configuration of the present embodiment, in the lighting control of the backlight 10, the lighting control focusing on the moving image existence block including the moving image can be performed. For example, when a scroll video in which characters are moved in a part of the screen is added to a pre-captured video image, the scroll video is displayed clearly with reduced blurring of the image. Is preferred.
[0133]
In the above embodiment, the BL waveform control circuit 8 performs the lighting control of the backlight 10 in accordance with the appearance state of the moving image existence block in one vertical period, that is, changes it. However, the present invention is not limited to this, and the BL waveform control circuit 8 performs the lighting control on the backlight 10 when the same result is continuously generated over a plurality of vertical periods with respect to the appearance state of the moving image existence block. You may make it change into the thing according to.
[0134]
  By performing such control, it is possible to prevent the occurrence of flicker due to frequent changes in the lighting control for the backlight 10.
  Note that the backlight driving device described above has a plurality of scanning lines arranged in one direction, and these scanning lines are sequentially scanned to drive a backlight of a display panel in which a display signal is written to a pixel corresponding to each scanning line. In the backlight driving apparatus, the display area of the display panel is divided into a plurality of blocks with a plurality of adjacent scanning line groups as one block, and each block in the image of one vertical period input to the display panel is divided. According to the appearance state in one vertical period of the moving image detection means for detecting the presence or absence of a moving image, and the moving image existence block detected as a block including the moving image by the moving image detection means, the drive voltage of the backlight in one vertical period It may be configured to include a backlight control means for adjusting the waveform and phase.
  Further, the backlight driving method described above has a plurality of scanning lines arranged in one direction, and these scanning lines are sequentially scanned, and a display signal is written to pixels corresponding to the scanning lines. , The display area of the display panel is divided into a plurality of blocks with a plurality of adjacent scanning line groups as one block, and the presence / absence of a moving image for each block in the image of one vertical period input to the display panel is detected. And a waveform and a phase of the backlight driving voltage in one vertical period according to the appearance state in one vertical period of the moving image existence block detected as the block including the moving image in the first step. And a second step of adjusting.
  According to the above configuration, the backlight drive voltage within one vertical period is determined by the backlight control unit according to the appearance state of the moving image existence block detected as a block including the moving image by the moving image detecting unit in one vertical period. Are adjusted in waveform and phase.
  As described above, in the configuration in which the display area of the display panel is divided into a plurality of blocks and the presence / absence of a moving image is detected for each block, for example, when a moving image exists in part of an image in one vertical period, the moving image It is possible to appropriately cope with displaying high quality. That is, according to various appearance states in one vertical period of the moving image existence block, it is possible to control the lighting of the backlight to an optimum state for suppressing, for example, luminance unevenness. High quality can be done. The processing as described above is, for example, control of the lighting timing and lighting period of the backlight, so that complicated circuits and components are not required and can be performed at low cost.
[0137]
【The invention's effect】
  The backlight driving device of the present invention divides the display area of the display panel into a plurality of blocks with a plurality of adjacent scanning line groups as one block, and in an image of one vertical period input to the display panel. A moving image detecting means for detecting the presence or absence of a moving image for each block; a contour steep image detecting means for detecting the presence or absence of an image having a steep outline for each block in an image of one vertical period input to the display panel; According to the appearance state in one vertical period of a moving image existence block that is a block that includes an image detected by the moving image detection unit as a moving image and detected as a contour steep image by the contour steep image detection unit. And a backlight control means for adjusting the waveform and phase of the drive voltage of the backlight.
[0138]
As described above, in the configuration in which the display area of the display panel is divided into a plurality of blocks and the presence or absence of an image that is a moving image and a sharp contour image is detected for each block, for example, the above-described part of the image in one vertical period When an image exists, it is possible to appropriately cope with displaying the image with high quality. That is, according to various appearance states in one vertical period of the moving image existence block, it is possible to control the lighting of the backlight to an optimum state for suppressing, for example, luminance unevenness. High quality can be done. The processing as described above is, for example, control of the lighting timing and lighting period of the backlight, so that complicated circuits and components are not required and can be performed at low cost.
[0139]
Furthermore, since the lighting of the backlight is controlled not according to the appearance state of the moving image existence block including the moving image but according to the appearance state of the moving image existence block including the image that is the moving image and the contour sharp image, it is displayed truly. It is possible to control the lighting of the backlight corresponding to the block whose quality can be improved. Accordingly, it is possible to prevent a situation where useless lighting control is performed and a situation where the display quality of a moving image is not improved without performing lighting control that should be originally performed.
[0140]
For example, if the shutter speed at the time of shooting is slow even for a moving image, the effect of performing backlight lighting control, for example, impulse conversion, according to the appearance state of the moving image existence block including the moving image is small.
[0141]
On the other hand, images with fast shutter speeds at the time of shooting have steep outlines (edges) even if they are moving images, and backlight lighting control, for example, impulse generation, according to the appearance state of moving image existence blocks including such moving images Performing this has a great effect of improving the display quality of moving images. For example, if the title telop scrolls left and right in the lower part of the screen and the background is also a moving image, only the lower part of the screen has the effect of impulse. Therefore, the configuration of the present invention is effective in improving the display quality of a character image (for example, title telop) that scrolls to the left and right of the screen, for example.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a liquid crystal display device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a state in which a display area in the liquid crystal panel shown in FIG. 1 is divided into a plurality of blocks.
FIG. 3 is a flowchart showing operations of the comparison circuit, the comparison result storage circuit, and the BL waveform control circuit shown in FIG. 1;
4 is a graph showing a count value of pixels determined to be a moving image for each block shown in FIG. 2, and showing a case where one block is a moving image existence block. FIG.
FIG. 5 is a waveform diagram of an input voltage to the inverter circuit in accordance with the appearance state of the moving image existence block shown in FIG.
6 is another example of a graph showing the count value of pixels determined to be a moving image for each block shown in FIG. 2, and showing a case where there is no moving image existence block.
7 is a waveform diagram of the input voltage to the inverter circuit determined from the graph shown in FIG. 6 when there is no moving image existence block.
FIG. 8 is another example of a graph showing the count value of pixels determined to be a moving image for each block shown in FIG. 2, and shows a case where two consecutive blocks are moving image existence blocks. .
9 is a waveform diagram of an input voltage to the inverter circuit in accordance with the appearance state of the moving image existence block shown in FIG.
FIG. 10 is still another example of a graph showing the count value of pixels determined to be a moving image for each block shown in FIG. 2, and shows a case where two non-consecutive blocks are moving image existence blocks. is there.
FIG. 11 is still another example of a graph showing the count value of pixels determined to be a moving image for each block shown in FIG. 2, and shows a case where all the blocks are moving image existence blocks.
FIG. 12A is a waveform diagram showing a case where the timing of backlight blinking and liquid crystal response is appropriate, and FIG. 12B is a waveform diagram showing a case where the timing is inappropriate. .
FIG. 13 is a block diagram showing a liquid crystal display device according to another embodiment of the present invention.
14 is a schematic diagram illustrating an example of an image including a moving image that can be appropriately handled by the liquid crystal display device illustrated in FIG. 13;
15 is a block diagram illustrating another example of the liquid crystal display device illustrated in FIG. 1. FIG.
16A is a schematic block diagram showing a configuration of the liquid crystal acceleration circuit shown in FIG. 15, and FIG. 16B shows the operation of the signal correction circuit shown in FIG. 16A. It is a wave form diagram to explain.
17 is a waveform diagram showing a relationship between an input voltage waveform to the inverter circuit and a liquid crystal response waveform by signal writing corresponding to the cases shown in FIGS. 4 and 5. FIG.
[Explanation of symbols]
1 Liquid crystal panel (display panel)
5 Image memory
6 Comparison circuit (moving image detection means)
7 Comparison result storage circuit (moving image detection means)
8 BL waveform control circuit (moving image detection means, backlight control means)
9 Inverter circuit
10 Backlight
11 Edge detection circuit (contour steep image detection means)
12 Liquid crystal acceleration circuit
12a comparison circuit
12b Signal correction circuit

Claims (22)

In a backlight driving device that has a plurality of scanning lines arranged in one direction and drives the backlight of a display panel in which the scanning lines are sequentially scanned and a display signal is written to pixels corresponding to the scanning lines.
A moving image that divides a display area of the display panel into a plurality of blocks with a plurality of adjacent scanning line groups as one block, and detects the presence or absence of a moving image for each block in an image of one vertical period input to the display panel Detection means;
A contour steep image detecting means for detecting the presence or absence of an image having a steep contour for each block in an image of one vertical period input to the display panel;
According to the appearance state in one vertical period of a moving image existence block that is a block including an image detected by the moving image detecting unit as a moving image and detected as a contour steep image by the contour steep image detecting unit. A backlight driving device comprising: backlight control means for adjusting a waveform and phase of a driving voltage of the backlight.   The moving image detecting means detects the presence or absence of a moving image by comparing a total value of the number of moving image pixels included in each block with a threshold value, and the threshold value in the block in which the total value of the moving image pixel number is the maximum value. The backlight driving device according to claim 1, wherein the backlight driving device is changed according to a total value of the number of moving image pixels.   The moving image detection means sets the threshold to a value of 1 / n 2 (n is a positive integer) of the total number of moving image pixels in the block in which the total value of moving image pixels is the maximum value. The backlight driving device according to claim 2.   The said backlight control means adjusts so that a backlight may light up from the timing when the response for the display by writing the display data with respect to the said moving image presence block is substantially completed. Backlight drive device.   2. The backlight driving device according to claim 1, wherein the backlight control unit adjusts the backlight to be turned off at a timing when writing of display data to the moving image existence block is started. The backlight control means adjusts whether the backlight is turned on or off when only one block among all the blocks in one vertical period is the moving image existence block. Item 6. The backlight driving device according to Item 4 or 5.   2. The backlight driving device according to claim 1, wherein the backlight control unit adjusts so that the backlight is always turned on when none of the blocks is a moving image existence block.   The backlight drive device according to claim 1, wherein the backlight control unit adjusts the flashing frequency of the backlight to be higher when none of the blocks is a moving image existence block.   2. The backlight driving device according to claim 1, wherein the backlight control unit adjusts the backlight so that the backlight is always lit when all the blocks are moving image existing blocks.   2. The backlight driving device according to claim 1, wherein the backlight control unit adjusts the flashing frequency of the backlight to be high when all the blocks are moving image existing blocks.   2. The backlight driving device according to claim 1, wherein the backlight control unit adjusts the backlight so that the backlight is always lit when a plurality of discontinuous blocks are moving image existing blocks.   2. The backlight driving device according to claim 1, wherein the backlight control unit adjusts the flashing frequency of the backlight to be high when a plurality of discontinuous blocks are moving image existing blocks.   The backlight control means determines the waveform and phase of the backlight drive voltage in one vertical period when the same appearance state occurs in a plurality of vertical periods with respect to the appearance state in one vertical period of the moving image existence block. The backlight driving device according to claim 1, wherein the backlight driving device is adjusted. The backlight drive device drives a backlight of a progressive display panel,
2. The back according to claim 1, wherein the moving image detecting unit detects the presence or absence of a moving image for each block by comparing an image signal of a current frame with an image signal of a frame immediately before the current frame. Light drive device. The backlight drive device drives a backlight of an interlaced display panel,
2. The back of claim 1, wherein the moving image detection unit detects the presence or absence of a moving image for each block by comparing an image signal of a current field with an image signal of a field immediately preceding the current field. Light drive device. The backlight drive device drives a backlight of an interlaced display panel,
2. The back according to claim 1, wherein the moving image detecting unit detects the presence or absence of a moving image for each block by comparing an image signal of a current field with an image signal of a field immediately before the current field. Light drive device.   The moving image detecting means calculates a difference in gradation data for each pixel of the image signal to be compared, and compares the total number of moving image pixels whose difference is larger than the first threshold value with the second threshold value. The back light drive device according to claim 14, wherein the presence or absence of light is detected.   2. The backlight drive device according to claim 1, wherein the contour steep image detecting means detects a character image.   A display device comprising the backlight driving device according to claim 1. A comparison circuit that compares pixel gradation data to detect moving images, and a signal correction to detect moving image pixels based on the comparison results of the comparison circuit and to speed up the display response for these moving image pixels A display acceleration circuit having a signal correction circuit for performing
20. The display device according to claim 19, wherein the moving image detecting means detects the presence or absence of a moving image using a comparison result in a comparison circuit in the display speed-up circuit. In a backlight driving method for a display panel, which has a plurality of scanning lines arranged in one direction, the scanning lines are sequentially scanned, and a display signal is written to pixels corresponding to the scanning lines.
A display area of the display panel is divided into a plurality of blocks with a plurality of adjacent scanning line groups as one block, and the presence / absence of a moving image for each block in an image of one vertical period input to the display panel is detected. 1 step,
A second step of detecting the presence or absence of an image having a steep outline for each block in an image of one vertical period input to the display panel;
According to the appearance state in one vertical period of the moving image existence block which is a block including the image detected as the moving image in the first step and detected as the contour steep image in the second step, And a third step of adjusting the waveform and phase of the driving voltage of the backlight.   A liquid crystal television receiver comprising the display device according to claim 19 or 20.

Images