JP2008096521A - Video display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video display apparatus capable of reducing the occurrence of flickering while improving moving picture blur caused in a moving picture display. <P>SOLUTION: An LCD controller 15 inserts a black frame of a high black signal level to a video frame of the fast moving picture during each video frame period, and outputs the signal to a panel driving circuit 18, and outputs a backlight control signal of an always HL level to a backlight control circuit 16. The LCD controller 15 inserts a black frame of about middle black signal level into the video frame of each video frame in each video frame period, and outputs the signal to the panel driving circuit 18 with respect to the video frame of an ordinary moving picture and outputs the backlight control signal of an H level in a period of half each video frame period to the moving picture control circuit 16. The LCD controller 15 outputs the video frame of nearly a static picture as it is to the panel driving circuit 18 and outputs the backlight control signal of the HL level in the period of 1/5 each video frame period to the backlight control circuit 16. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention can reduce the occurrence of flicker while improving the motion blur that occurs when displaying a moving image by inserting a black signal corresponding to each video frame within each video frame period of the video signal. The present invention relates to an image display device.

  In recent years, liquid crystal displays (LCD) capable of realizing high-definition display, low power consumption, light weight, space saving, and the like have become widespread. When a moving image is displayed on a CRT (cathode ray tube) display conventionally used as an image display device, the liquid crystal display is perceived by the human vision as the outline of the moving part is blurred. “Movie blur” is likely to occur. This is because the CRT display emits light only for a few milliseconds from the time when the electron beam hits the phosphor on the tube surface, and thereby the image is displayed instantaneously, thereby being an impulse type display device. This is because the liquid crystal display is a hold-type display device that holds display light for one frame period from the time when writing of data to the pixel is completed until the next writing is started.

Therefore, in Patent Literature 1 and Patent Literature 2, a black image is inserted between time-series video frames by writing the video signal and the black signal to the liquid crystal display panel within one video frame period of the video signal. A display device that performs pseudo impulse-type display control is disclosed. As a result, the display accuracy of the hold-type liquid crystal display can be brought close to the display accuracy of the impulse-type CRT display, and moving image blurring that occurs when displaying a moving image on the liquid crystal display can be reduced and displayed. Degradation of image quality can be improved.
JP 2004-233932 A JP 2003-186454 A

  In the liquid crystal displays as disclosed in Patent Document 1 and Patent Document 2, the black signal level of the black signal inserted in each video frame period is often a fixed value, and a black signal with a high black signal level is displayed. When inserted, flickering occurs in the displayed video, resulting in degradation of image quality, and when a black signal with a low black signal level is inserted, it is difficult to improve moving image blur well. Yes. In addition, a liquid crystal display in which a black signal of a fixed black signal level is inserted has a problem that the luminance of the appearance in the displayed video is lowered, and there is a possibility that the viewer may feel uncomfortable.

  The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the occurrence of flicker by inserting a black signal corresponding to the movement of a display target in an image based on the image signal. An object of the present invention is to provide a video display device capable of satisfactorily improving moving image blur while preventing deterioration of image quality.

  Another object of the present invention is to provide a black signal with a high black signal level (a black signal with a long insertion period or a black signal with a large number of black pixels) when the movement of the display target in the video based on the video signal is fast. When the movement of the display target in the video based on the video signal is slow, by inserting a black signal with a low black signal level (a black signal with a short insertion period or a black signal with a small number of black pixels), An object of the present invention is to provide a video display device capable of reducing the occurrence of flicker while satisfactorily improving the motion blur.

  Furthermore, another object of the present invention is to provide a video display device capable of displaying a good video with reduced changes in apparent luminance in the displayed video while satisfactorily improving the occurrence of motion blur and flicker. There is to do.

  A video display device according to the present invention includes a black insertion unit that inserts a black signal within each video frame period of a video signal composed of a plurality of video frames, and a display that displays the video signal into which the black insertion unit has inserted the black signal. A difference calculating means for calculating a difference amount between previous and next video frames in time series, and a black inserted by the black inserting means according to the difference amount calculated by the difference calculating means. Specifying means for specifying the black signal level of the signal, wherein the black inserting means is configured to insert a black signal of the black signal level specified by the specifying means.

  According to the present invention, a video display device that inserts a black signal in each video frame period of a video signal composed of a plurality of video frames and displays the video signal with the black signal inserted therein A difference amount between frames is calculated, and a black signal level of a black signal to be inserted is specified according to the calculated difference amount. Therefore, in each video signal, it is possible to insert a black signal having a black signal level corresponding to the difference between the video frames that move back and forth in time series.

  In the video display device according to the present invention, the specifying unit specifies the black signal level of the black signal inserted by the black inserting unit as high / low according to the magnitude of the difference amount calculated by the difference calculating unit. It is comprised so that it may carry out.

  According to the present invention, the video display device inserts a black signal having a high black signal level into a corresponding video frame period when the difference amount between video frames preceding and following in time series in each video signal is large. In addition, when the video display device has a small difference amount between video frames that move back and forth in time series in each video signal, a black signal having a low black signal level is inserted into the corresponding video frame period.

  The video display device according to the present invention includes a liquid crystal display panel, a backlight disposed on the back surface of the liquid crystal display panel, and the luminance of the backlight according to the high / low of the black signal level specified by the specifying means. And a driving means for controlling the height to high / low.

  According to the present invention, when the black signal level of the black signal specified according to the difference between the video frames preceding and following in time series in each video signal is high, the video display device is disposed on the back surface of the liquid crystal display panel. The backlight brightness is controlled to be high, and when the black signal level of the black signal is low, the backlight brightness is controlled to be low.

  A video display device according to the present invention includes a black insertion unit that inserts a black signal within each video frame period of a video signal composed of a plurality of video frames, and a display that displays the video signal into which the black insertion unit has inserted the black signal. And a difference calculating means for calculating a difference amount between the preceding and succeeding video frames in time series, and for each video frame period according to the difference amount calculated by the difference calculating means. Specifying means for specifying an insertion period of a black signal to be inserted by the black insertion means, wherein the black insertion means is configured to insert a black signal of the insertion period specified by the specification means, To do.

  According to the present invention, a video display device that inserts a black signal in each video frame period of a video signal composed of a plurality of video frames and displays the video signal with the black signal inserted therein A difference amount between frames is calculated, and an insertion period for each video frame period of a black signal to be inserted is specified according to the calculated difference amount. Therefore, in each video signal, it is possible to insert a black signal in an insertion period according to the difference amount between video frames that move back and forth in time series.

  In the video display device according to the present invention, the specifying unit specifies the insertion period of the black signal inserted by the black insertion unit as long / short according to the magnitude of the difference amount calculated by the difference calculation unit. It is configured as described above.

  According to the present invention, when the difference amount between video frames preceding and following in time series is large in each video signal, the video display device inserts a black signal having a long insertion period within the corresponding video frame period. In addition, when the video display device has a small difference amount between video frames that are chronologically changed in each video signal, a black signal having a short insertion period is inserted into the corresponding video frame period.

  The video display device according to the present invention includes a liquid crystal display panel, a backlight disposed on the back surface of the liquid crystal display panel, and brightness of the backlight according to the length / shortness of the insertion period specified by the specifying means. And driving means for controlling to high / low.

  According to the present invention, the video display device is arranged on the back surface of the liquid crystal display panel when the black signal insertion period specified according to the difference amount between the video frames preceding and following in time series in each video signal is long. The backlight brightness is controlled to be high, and when the black signal insertion period is short, the backlight brightness is controlled to be low.

  A video display device according to the present invention includes a black insertion unit that inserts a black signal within each video frame period of a video signal composed of a plurality of video frames, and a display that displays the video signal into which the black insertion unit has inserted the black signal. The black insertion means is configured to insert a black signal frame including a plurality of black pixels in each video frame period, and between the previous and next video frames in time series. Difference calculating means for calculating a difference amount; and specifying means for specifying the number of black pixels included in the black signal frame inserted by the black insertion means according to the difference amount calculated by the difference calculating means; The black insertion unit is configured to insert a black signal frame including black pixels of the number of pixels specified by the specifying unit.

  According to the present invention, a video display device that inserts a black signal frame including a plurality of black pixels in each video frame period of a video signal composed of a plurality of video frames and displays the video signal in which the black signal frame is inserted. However, the difference amount between the preceding and succeeding video frames is calculated in time series, and the number of black pixels included in the black signal frame to be inserted is specified according to the calculated difference amount. Therefore, in each video signal, it is possible to insert a black signal frame including black pixels having the number of pixels corresponding to the difference amount between the video frames preceding and following in time series.

  In the video display device according to the present invention, the specifying unit determines the number of black pixels included in the black signal frame inserted by the black insertion unit according to the magnitude of the difference amount calculated by the difference calculation unit. It is characterized by being configured so as to be specified in a large number / a small number.

  According to the present invention, the video display device inserts a black signal frame having a large number of black pixels in a corresponding video frame period when a difference amount between video frames preceding and following in time series in each video signal is large. To do. In addition, when the video display device has a small difference amount between video frames that move back and forth in time series in each video signal, a black signal frame with a small number of black pixels is inserted in the corresponding video frame period.

  The video display device according to the present invention includes a liquid crystal display panel, a backlight disposed on a back surface of the liquid crystal display panel, and brightness of the backlight according to the number of pixels specified by the specifying unit. And driving means for controlling to high / low.

  According to the present invention, the video display device is arranged on the back surface of the liquid crystal display panel when the number of black pixels specified according to the amount of difference between video frames preceding and following in time series in each video signal is large. The backlight brightness is controlled to be high, and when the number of black pixels is small, the backlight brightness is controlled to be low.

  In the present invention, the video display device inserts a black signal having a black signal level corresponding to a difference amount between video frames preceding and following in time series in each video signal in a corresponding video frame period. Therefore, it is possible to insert a black signal with a black signal level corresponding to the movement of the display target in the video based on the video signal, thereby enabling pseudo-impulse display control and preventing image quality deterioration. Video blur can be improved satisfactorily.

  In the present invention, the video display device has a high black signal level when the difference amount between the video frames preceding and following in time series in each video signal is large, that is, when the movement of the display target in the video based on the video signal is fast. By inserting the black signal in the corresponding video frame period, it is possible to improve the moving image blur well and display a video with excellent moving image characteristics. In addition, when the video display device has a small difference between video frames that are chronologically followed in each video signal, that is, when the movement of the display target in the video based on the video signal is slow, the black signal with a low black signal level Is inserted in the corresponding video frame period, the occurrence of flicker can be reduced and the deterioration of the image quality can be prevented.

  In the present invention, when the video display device inserts a black signal having a high black signal level within each video frame period, the luminance of the backlight is controlled to be high, and the black signal level is set within each video frame period. When a low black signal is inserted, it is possible to reduce a change in apparent luminance in a display image that may be caused by a change in the black signal level of the inserted black signal by controlling the luminance of the backlight low. . As a result, it is possible to display a good video with reduced discomfort that can be given to the viewer based on a change in luminance in the displayed video, while favorably improving the occurrence of moving image blur and flicker.

  In the present invention, the video display device inserts a black signal in an insertion period corresponding to a difference amount between video frames preceding and following in time series in each video signal in a corresponding video frame period. Therefore, it is possible to insert a black signal with an insertion period corresponding to the movement of the display target in the video based on the video signal, thereby enabling pseudo-impulse-type display control and preventing a deterioration in image quality. The blur can be improved satisfactorily.

  In the present invention, when the video display device has a large amount of difference between video frames preceding and following in time series in each video signal, that is, when the movement of the display target in the video based on the video signal is fast, the corresponding video frame period By inserting a black signal having a long insertion period into the image, it is possible to improve the moving image blur well and display an image with excellent moving image characteristics. In addition, when the video display device has a small difference between video frames that are chronologically changed in each video signal, that is, when the movement of the display target in the video based on the video signal is slow, within the corresponding video frame period By inserting a black signal with a short insertion period, it is possible to reduce the occurrence of flicker and prevent image quality deterioration.

  In the present invention, when the video display device inserts a black signal having a long insertion period within each video frame period, the luminance of the backlight is controlled to be high, and the black with a short insertion period within each video frame period. In the case of inserting a signal, by controlling the luminance of the backlight to be low, it is possible to reduce a change in apparent luminance in a display image that may be caused by a change in the insertion period of the inserted black signal. As a result, it is possible to display a good video with reduced discomfort that can be given to the viewer based on a change in luminance in the displayed video, while favorably improving the occurrence of moving image blur and flicker.

  In the present invention, the video display device inserts a black signal frame including black pixels having the number of pixels corresponding to a difference amount between video frames preceding and following in time series in each video signal in a corresponding video frame period. Therefore, it is possible to insert a black signal frame including black pixels having the number of pixels corresponding to the movement of the display target in the video based on the video signal, thereby enabling a pseudo impulse type display control and degrading the image quality. It is possible to satisfactorily improve the motion blur while preventing the image.

  In the present invention, when the video display device has a large amount of difference between video frames that are chronologically sequenced in each video signal, that is, when the movement of the display target in the video based on the video signal is fast, the number of black pixels By inserting a large number of black signal frames in the corresponding video frame period, it is possible to improve the moving image blur well and display a video with excellent moving image characteristics. Further, when the video display device has a small difference amount between video frames that are chronologically changed in each video signal, that is, when the movement of the display target in the video based on the video signal is slow, the number of black pixels is small. By inserting the black signal frame into the corresponding video frame period, it is possible to reduce the occurrence of flicker and prevent the deterioration of the image quality.

  In the present invention, when the video display apparatus inserts a black signal frame having a large number of black pixels in each video frame period, the backlight luminance is controlled to be high, and the black signal frame is black in each video frame period. In the case of inserting a black signal frame with a small number of pixels, by controlling the backlight brightness to be low, in a display image that may be caused by a change in the number of black pixels included in the inserted black signal frame Changes in apparent luminance can be reduced. As a result, it is possible to display a good video with reduced discomfort that can be given to the viewer based on a change in luminance in the displayed video, while favorably improving the occurrence of moving image blur and flicker.

  Hereinafter, a video display apparatus according to the present invention will be described in detail with reference to the drawings showing a liquid crystal television as an embodiment thereof.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration example of a main part of a liquid crystal television of Embodiment 1 as a video display device according to the present invention. The liquid crystal television 1 of the first embodiment is an analog tuner (not shown) for receiving analog video signals such as UHF television broadcast signals and VHF television broadcast signals, for example, terrestrial digital broadcast signals or BS digital. An analog tuner that can be connected to a digital tuner (not shown) for receiving a digital video signal such as a broadcast signal, a video processing device (not shown) such as a digital camera and a recording device, etc. Then, the video is displayed based on the video signal input from either the digital tuner or the video processing device.

  The liquid crystal television 1 according to the first embodiment includes a video signal processing circuit 12, an LCD controller 15, a backlight control circuit 16, a backlight 17, a panel drive circuit 18, a liquid crystal display panel 19, and the like. Further, the liquid crystal television 1 includes a control unit 10 configured by a CPU (Central Processing Unit) or an MPU (Micro Processor Unit) in which a ROM and a RAM are incorporated.

  The control unit 10 controls the operation of each hardware unit as described above, and appropriately reads and executes a control program stored in advance in a ROM built in the controller. The ROM stores in advance various control programs necessary for operating the liquid crystal television 1 as the video display device according to the present invention. The RAM is composed of SRAM, SDRAM, or the like, and temporarily stores data generated when the control unit 10 executes the control program.

  As described above, the video signal processing circuit 12 performs, for example, YC separation processing for separating a video signal input from any of an external analog tuner, digital tuner, or video processing device into a luminance signal and a color difference signal, Perform signal processing such as color conversion processing using a matrix, IP conversion processing that converts interlaced video signals into progressive video signals, and A / D conversion processing that converts analog signals into digital signals as needed. To do. Note that a frame memory 11 is connected to the control unit 10 and the video signal processing circuit 12, and the control unit 10 frames the video signal when various signal processes are executed by the video signal processing circuit 12 in units of frames. The data is stored in the memory 11 as appropriate.

  In addition, the video signal processing circuit 12 performs various signal processes as described above, and repeatedly reads each video frame twice at a double frame rate with respect to the video signal stored in the frame memory 11. A frame rate conversion process is executed, and a scaling process corresponding to the number of pixels of the liquid crystal display panel 19 is performed by a scaling circuit (not shown), and then a video signal is output to the motion detection circuit 13 and the LCD controller 15. . The video signal output from the video signal processing circuit 12 is composed of, for example, 30 video frames per second.

  FIG. 2 is a waveform diagram for explaining a video signal in the liquid crystal television 1 of the first embodiment. The input video signal is input to the video signal processing circuit 12 of the liquid crystal television 1 at the timing when the input synchronization signal in FIG. 2 changes from the H level to the L level, and the video signal processing circuit 12 performs each signal processing as described above. After that, the output video signal is output to the motion detection circuit 13 and the LCD controller 15 at the timing when the output synchronization signal in FIG. 2 changes from the H level to the L level. 2A to 2C will be described later.

  The LCD controller 15 includes a panel drive circuit 18 that drives the liquid crystal display panel 19 and a backlight control circuit (drive means) 16 that controls turning on and off of the backlight 17 disposed on the back surface of the liquid crystal display panel 19. It is connected. The liquid crystal display panel 19 is configured, for example, by arranging a plurality of liquid crystal elements in a two-dimensional matrix. The backlight 17 is configured using, for example, a cold cathode fluorescent lamp (CCFL). The LCD controller 15 drives the backlight control circuit 16 and the panel drive circuit 18 based on the video signal acquired from the video signal processing circuit 12 according to the control from the control unit 10, and displays the video based on the video signal on the liquid crystal display panel 19. To display.

  The liquid crystal television 1 according to the first embodiment further includes a motion detection circuit 13 and a black signal generation circuit 14. The motion detection circuit 13 includes a subtracter (not shown), and subtracts a difference amount between video frames that are sequentially and temporally input to the video signals sequentially input from the video signal processing circuit 12. It operates as a difference calculating means for calculating by Specifically, the motion detection circuit 13 calculates a difference value between pixel values of the corresponding pixels in two video frames that move back and forth in time series. Here, in this embodiment, each pixel of the video frame is, for example, 8-bit data, and the difference value of each pixel in the video frame also takes each value of 0 to 255.

  The motion detection circuit 13 executes a binarization process based on a threshold value stored in advance in the ROM of the control unit 10, for example, for each pixel difference value calculated between two video frames. Furthermore, the motion detection circuit 13 calculates a total value of the difference values of the binarized pixels, and sets the calculated total value as a difference amount between video frames. Furthermore, the motion detection circuit 13 compares the difference amount between the two video frames calculated as described above with, for example, a first threshold value stored in advance in the ROM of the control unit 10, and the difference amount is greater than the first threshold value. Is larger, it is determined that the video based on the corresponding video frame is a fast moving video.

  In addition, the motion detection circuit 13 compares the difference amount with a second threshold value that is smaller than the first threshold value when the difference amount is smaller than the first threshold value, and responds when the difference amount is larger than the second threshold value. When the video based on the video frame to be determined is a normal moving image, and the difference amount is smaller than the second threshold, it is determined that the video based on the corresponding video frame is almost a still image. The motion detection circuit 13 notifies the black signal generation circuit 14 of the determination result.

  The black signal generation circuit 14 operates as specifying means for specifying the black signal level of the black signal to be inserted within the corresponding video frame period according to the determination result notified from the motion detection circuit 13, and the specified black signal A black frame (black signal frame) composed of a black signal of a level is generated and output to the LCD controller 15. Specifically, when the black signal generation circuit 14 is notified from the motion detection circuit 13 that the video based on the corresponding video frame is a fast moving video, the black signal generation circuit 14 generates a black frame composed of a black signal with a high black signal level. Generated and output to the LCD controller 15. Further, when notified that the video based on the corresponding video frame is a normal moving image, the black signal generation circuit 14 generates a black frame composed of a black signal having a medium black signal level and outputs the black frame to the LCD controller 15. To do. In this embodiment, the black signal generation circuit 14 does not generate a black frame and notifies the corresponding video frame when the motion detection circuit 13 notifies that the video based on the corresponding video frame is almost a still image. No black signal is inserted within the period.

  The LCD controller 15 further converts the video signal output from the video signal processing circuit 12 into a three times higher frame rate and outputs it from the black signal generating circuit 14 in accordance with an instruction from the control unit 10. 2 is operated as black insertion means for inserting the corresponding black frame into each corresponding video frame period, and an output signal as shown in FIGS. 2A to 2C is output to the panel drive circuit 18 and FIG. A backlight control signal as shown in a) to (c) is output to the backlight control circuit 16.

  FIG. 2A shows an output signal output from the LCD controller 15 to the panel drive circuit 18 when the moving image frame of the moving image is displayed on the liquid crystal display panel 19, and the LCD controller 15 outputs the backlight control circuit 16. The backlight control signal to be output is shown. FIG. 2B shows an output signal output from the LCD controller 15 to the panel drive circuit 18 when the normal moving image frame is displayed on the liquid crystal display panel 19, and the LCD controller 15 displays the backlight control circuit 16. And a backlight control signal to be output to. FIG. 2C shows an output signal that the LCD controller 15 outputs to the panel drive circuit 18 when the almost still image video frame is displayed on the liquid crystal display panel 19, and an output signal that the LCD controller 15 outputs to the backlight control circuit 16. The backlight control signal to be displayed.

  For a video frame of a fast-moving moving image, the LCD controller 15 generates a black frame consisting of a black signal with a high black signal level, specifically a black frame consisting of, for example, a pixel having a pixel value of 255, for example. 14, and the acquired black frame is inserted into one-third of each video frame period with respect to the video frame output from the video signal processing circuit 12 as shown in FIG. In FIG. 2A, a video signal in which a black frame is inserted in the latter one third of the video frame period of the video frame A output from the video signal processing circuit 12 is shown. The LCD controller 15 outputs the video signal with the black frame inserted in this way to the panel drive circuit 18. Further, the LCD controller 15 always outputs an H level backlight control signal to the backlight control circuit 16 when displaying a fast-moving video frame on the liquid crystal display panel 19, thereby increasing the brightness of the backlight 17. Always control to H level.

  Further, as shown in FIG. 2B, the LCD controller 15 also performs the latter half of the video frame period of the video frame A output from the video signal processing circuit 12 for the normal video frame. A black frame is inserted in 1/3 period. For a normal video frame, the LCD controller 15 displays a black frame composed of a black signal with a medium black signal level, specifically a black frame composed of, for example, 128 pixels. The black frame acquired from the signal generation circuit 14 is inserted into the video frame output from the video signal processing circuit 12, and the video signal with the black frame inserted in this way is output to the panel drive circuit 18. Further, the LCD controller 15 outputs a backlight control signal shown in FIG. 2B to the backlight control circuit 16 when displaying a normal moving image video frame on the liquid crystal display panel 19, so that each video frame period is displayed. For example, control is performed so that the luminance of the backlight 17 becomes H level during a half period.

  Further, as shown in FIG. 2C, the LCD controller 15 converts the video frame output from the video signal processing circuit 12 to a frame rate three times as high as the video frame output from the video signal processing circuit 12. After the above, the data is output to the panel drive circuit 18 without inserting a black frame. Further, the LCD controller 15 outputs a backlight control signal shown in FIG. 2C to the backlight control circuit 16 in order to display a substantially still image video frame on the liquid crystal display panel 19. For example, during the period of 1/5, the brightness of the backlight 17 is controlled to be H level. Note that the luminance of the backlight 17 is controlled by PWM (Pulse Width Modulation) duty control. The shorter the H level period of the backlight control signal, the lower the luminance of the backlight 17, and the backlight control signal becomes lower. When it is always at the H level, the luminance of the backlight 17 is controlled to the maximum.

  As described above, the panel drive circuit 18 that has acquired the output signal from the LCD controller 15 writes an image on the liquid crystal display panel (display means) 19 in accordance with the acquired output signal and acquires the backlight control signal from the LCD controller 15. The control circuit 16 turns on and off the backlight 17 according to the acquired backlight control signal.

  As described above, when the video based on the video signal is a fast moving video, the luminance of the backlight 17 is always set while inserting a black frame composed of a black signal with a high black signal level into the corresponding video frame period. By controlling to the H level, it is possible to perform pseudo-impulse display control, to improve the motion blur well, to display a video with excellent motion characteristics, and with the insertion of a black frame It is possible to reduce a sense of discomfort that can be given to the viewer based on a change in luminance in the displayed video. Further, when the video based on the video signal is almost a still image, flicker can be prevented from occurring in the display video by not inserting a black frame. If the video based on the video signal is a normal moving image, the luminance of the backlight 17 is set to an intermediate level while inserting a black frame consisting of a black signal having a medium black signal level in each corresponding video frame period. By controlling the level, it is possible to reduce the occurrence of flicker in the displayed video while improving the motion blur well.

  Hereinafter, processing for inserting a black signal into a video signal to be displayed in the liquid crystal television 1 having the above-described configuration will be described. 3 and 4 are flowcharts showing the procedure of black signal insertion processing in the liquid crystal television 1 according to the first embodiment. The following processing is executed by the control unit 10 according to a control program stored in advance in a ROM built in the control unit 10.

  When the video signal is acquired from the outside (S1), the control unit 10 of the liquid crystal television 1 executes various signal processing by the video signal processing circuit 12 (S2), and the video signal subjected to the various signal processing is framed. The data is output to the motion detection circuit 13 and the LCD controller 15 in units. Next, the control unit 10 uses the motion detection circuit 13 to calculate a difference amount between two video frames moving back and forth in time series (S3), and the calculated difference amount is stored in advance in its own ROM. It is determined whether or not it is larger than one threshold (S4).

  When the motion detection circuit 13 determines that the calculated difference amount is greater than the first threshold value (S4: YES), the control unit 10 notifies the black signal generation circuit 14 to that effect, and the black signal generation circuit 14 Then, a black frame composed of a black signal having a high black signal level is generated (S5) and output to the LCD controller 15. Next, the controller 10 always outputs a backlight control signal of H level to the backlight control circuit 16 by the LCD controller 15 (S6), and the black frame generated in step S5 is output from the video signal processing circuit 12. The inserted video frame is inserted and output to the panel drive circuit 18 (S7).

  When determining that the difference amount calculated in step S3 is smaller than the first threshold value (S4: NO), the control unit 10 determines whether the difference amount is larger than the second threshold value stored in advance in its own ROM. Is determined (S8). When the control unit 10 determines that the difference amount is larger than the second threshold (S8: YES), the control unit 10 notifies the black signal generation circuit 14 to that effect, and the black signal generation circuit 14 causes the black signal level to be medium. A black frame composed of a black signal is generated (S9) and output to the LCD controller 15. Next, the controller 10 causes the LCD controller 15 to output a backlight control signal whose level is half of each video frame period to the backlight control circuit 16 (S10), and the black frame generated in step S9. Are inserted into the video frame input from the video signal processing circuit 12 and output to the panel drive circuit 18 (S11).

  When the control unit 10 determines that the difference amount calculated in step S3 is smaller than the second threshold value (S8: NO), the control unit 10 notifies the black signal generation circuit 14 to that effect, and sends a black frame to the black signal generation circuit 14. Without being generated, the LCD controller 15 outputs a backlight control signal having an H level for 1/5 of each video frame period to the backlight control circuit 16 (S12) and is input from the video signal processing circuit 12 The video frame is output as it is to the panel drive circuit 18 (S13). As a result, the backlight control circuit 16 turns on the backlight 17 based on the backlight control signal input from the LCD controller 15, and the panel drive circuit 18 displays the video based on the video frame input from the LCD controller 15. The image is displayed on the liquid crystal display panel 19.

  The control unit 10 determines whether or not the display of all the video frames of the video signal input to the video signal processing circuit 12 is finished (S14), and if the display of all the video frames is not finished. If it is determined (S14: NO), the process returns to step S3, and the above-described processes of steps S3 to S14 are repeated until the display of all the video frames is completed. Further, when the control unit 10 determines that the display of all the video frames has been completed (S14: YES), the control unit 10 ends the above-described processing.

  In the first embodiment described above, the total value of the difference values of all the pixels in each video frame is used as the difference amount between two video frames that move back and forth in time series. However, the present invention is not limited to this. It is also possible to use the total difference value of each pixel in a predetermined area in the video frame. Specifically, in each video frame having 1920 × 1080 pixels, for example, when the total difference value of each pixel in a predetermined 100 × 100 pixel block is less than 10, it is determined that the image is almost a still image. Then, when the total value is less than 50, it may be determined that the video is a normal moving image, and when the total value is 50 or more, it may be determined that the video is fast moving.

  In the first embodiment described above, the difference between two video frames moving back and forth in time series is compared with two threshold values, the first threshold value and the second threshold value, and the video based on the video signal to be displayed moves. Whether it is a fast video, a normal video, or almost a still image, a black frame consisting of a black signal with a black signal level corresponding to each video signal is inserted into each video frame period. The configuration has been described. However, for example, the amount of difference between video frames is compared with one threshold value, and the video based on the video signal to be displayed is classified as a moving image or almost a still image, and according to each video signal. A black frame may be inserted into each video frame period.

(Embodiment 2)
The liquid crystal television according to the second embodiment will be described below. Note that the internal configuration of the liquid crystal television of Embodiment 2 is the same as that of the liquid crystal television 1 of Embodiment 1 described above, and thus the description of the configuration is omitted.

  FIG. 5 is a waveform diagram for explaining a video signal in the liquid crystal television 1 of the second embodiment. Similarly to the liquid crystal television 1 of the first embodiment described above, the liquid crystal television 1 of the second embodiment receives the input video signal to the video signal processing circuit 12 at the timing when the input synchronization signal in FIG. 5 changes from the H level to the L level. Entered. The video signal processing circuit 12 performs various signal processing as described in the first embodiment, and then moves the output video signal to the motion detection circuit at the timing when the output synchronization signal in FIG. 5 changes from the H level to the L level. 13 and the LCD controller 15.

  The motion detection circuit 13 calculates the amount of difference between two video frames that are temporally sequenced with respect to the video signals sequentially input from the video signal processing circuit 12, and uses the calculated difference amount as, for example, the control unit 10. The first threshold value and the second threshold value stored in the ROM in advance are compared to determine whether the video based on the corresponding video frame is a fast moving movie, a normal movie, or a substantially still image. The determination result is notified to the black signal generation circuit 14 and the LCD controller 15.

  In the liquid crystal television 1 of Embodiment 2, when the black signal generation circuit 14 is notified from the motion detection circuit 13 that the video based on the corresponding video frame is a fast moving video, or based on the corresponding video frame When it is notified that the video is a normal moving image, a black frame including a black signal having a predetermined black signal level is generated and output to the LCD controller 15. Note that the black signal generation circuit 14 does not generate a black frame when it is notified from the motion detection circuit 13 that the video based on the corresponding video frame is almost a still image.

  The LCD controller 15 further converts the video signal output from the video signal processing circuit 12 into a triple frame rate in accordance with an instruction from the control unit 10, and receives the input from the black signal generation circuit 14. The black frame is operated as black insertion means for inserting the black frame within each corresponding video frame period. At this time, the LCD controller 15 operates as a specifying unit that specifies an insertion period of a black signal to be inserted into each corresponding video frame period according to the determination result notified from the motion detection circuit 13.

  Specifically, the LCD controller 15 notifies the video frame acquired from the video signal processing circuit 12 when the motion detection circuit 13 notifies that the video based on the corresponding video frame is a fast moving video. A black frame input from the black signal generation circuit 14 is inserted in a half period of each video frame period. In addition, when the motion controller circuit 13 notifies that the video based on the corresponding video frame is a normal moving image, the LCD controller 15 performs each video frame period for the video frame acquired from the video signal processing circuit 12. The black frame input from the black signal generation circuit 14 is inserted during a period of 1/3 of the period. Further, the LCD controller 15 does not insert a black frame into the video frame acquired from the video signal processing circuit 12 when notified from the motion detection circuit 13 that the video based on the corresponding video frame is almost a still image. .

  The LCD controller 15 inserts the black frame input from the black signal generation circuit 14 into the video frame acquired from the video signal processing circuit 12 based on the insertion period specified as described above, and FIG. Output signals as shown in a) to (c) are output to the panel drive circuit 18. The LCD controller 15 outputs a backlight control signal as shown in FIGS. 5A to 5C to the backlight control circuit 16.

  FIG. 5A shows an output signal that the LCD controller 15 outputs to the panel drive circuit 18 when the moving image frame of a fast moving image is displayed on the liquid crystal display panel 19, and the LCD controller 15 to the backlight control circuit 16. The backlight control signal to be output is shown. FIG. 5B shows an output signal output from the LCD controller 15 to the panel drive circuit 18 when the normal moving image frame is displayed on the liquid crystal display panel 19, and the LCD controller 15 displays the backlight control circuit 16. And a backlight control signal to be output to. FIG. 5C shows an output signal that the LCD controller 15 outputs to the panel drive circuit 18 when the almost still image video frame is displayed on the liquid crystal display panel 19, and an output signal that the LCD controller 15 outputs to the backlight control circuit 16. The backlight control signal to be displayed.

  As shown in FIG. 5A, for the video frame of a fast moving video, the LCD controller 15 first 1 / video frame period output from the video signal processing circuit 12 in the first video frame period. The black frame is inserted in the period of 3 and the last 1/3 period, and the black frame is inserted in the center 1/3 period of the second video frame period, and output to the panel drive circuit 18. Further, the LCD controller 15 always outputs an H level backlight control signal to the backlight control circuit 16 when displaying a fast-moving video frame on the liquid crystal display panel 19, thereby increasing the brightness of the backlight 17. Always control to H level.

  Further, as shown in FIG. 5B, for a normal moving image frame, the LCD controller 15 、 of the second half of each image frame period of the image frame A output from the image signal processing circuit 12. During this period, a black frame is inserted and output to the panel drive circuit 18. Further, when the LCD controller 15 displays a normal moving image frame on the liquid crystal display panel 19, the LCD controller 15 outputs a backlight control signal shown in FIG. 5B to the backlight control circuit 16. For example, the luminance of the backlight 17 is controlled to be H level in a half period.

  Further, as shown in FIG. 5C, the LCD controller 15 converts the video frame output from the video signal processing circuit 12 to a frame rate three times as high as that of the video frame of the still image. After the above, the data is output to the panel drive circuit 18 without inserting a black frame. Further, the LCD controller 15 outputs a backlight control signal shown in FIG. 5C to the backlight control circuit 16 in order to display a substantially still image video frame on the liquid crystal display panel 19, so that each video frame period is displayed. For example, the luminance of the backlight 17 is controlled to be H level in a period of 1/5.

  As described above, the panel drive circuit 18 that has acquired the output signal from the LCD controller 15 writes an image on the liquid crystal display panel 19 according to the acquired output signal, and the backlight control circuit 16 that has acquired the backlight control signal from the LCD controller 15 is Then, the backlight 17 is turned on and off according to the acquired backlight control signal.

  As described above, when the video based on the video signal is a fast moving video, the backlight is inserted while inserting a black frame in a long insertion period (for example, half of the video frame period) for each video frame period. By controlling the luminance of 17 to H level at all times, pseudo-impulse type display control can be performed, moving image blur can be improved satisfactorily, video with excellent moving image characteristics can be displayed, and black It is possible to reduce a sense of discomfort that can be given to the viewer based on a change in luminance in a display image that occurs with the insertion of a frame. In addition, when the video based on the video signal is almost a still image, flicker can be prevented from occurring in the display video by not inserting the black frame into the video frame. In addition, when the video based on the video signal is a normal moving image, a black frame is inserted in a middle period (for example, 1/3 of the video frame period) with respect to each video frame period. By controlling the brightness of the light 17 to an intermediate level, it is possible to reduce the occurrence of flicker in the displayed image while satisfactorily improving the motion blur.

  Hereinafter, processing for inserting a black signal into a video signal to be displayed in the liquid crystal television 1 having the above-described configuration will be described. 6 and 7 are flowcharts showing the procedure of black signal insertion processing in the liquid crystal television 1 according to the second embodiment. The following processing is executed by the control unit 10 according to a control program stored in advance in a ROM built in the control unit 10.

  When the video signal is acquired from the outside (S21), the control unit 10 of the liquid crystal television 1 executes various signal processing by the video signal processing circuit 12 (S22), and the video signal subjected to the various signal processing is framed. The data is output to the motion detection circuit 13 and the LCD controller 15 in units. Next, the control unit 10 uses the motion detection circuit 13 to calculate a difference amount between two video frames that are moved back and forth in time series (S23), and the calculated difference amount is stored in advance in its own ROM. It is determined whether or not it is larger than one threshold (S24).

  When the motion detection circuit 13 determines that the calculated difference amount is larger than the first threshold (S24: YES), the control unit 10 notifies the black signal generation circuit 14 and the LCD controller 15 to that effect, and the black signal The generation circuit 14 generates a black frame composed of a black signal of a predetermined black signal level (S25) and outputs it to the LCD controller 15. Next, the controller 10 always outputs a backlight control signal of H level to the backlight control circuit 16 by the LCD controller 15 (S26), and the black frame generated in step S25 is output from the video signal processing circuit 12. The input video frame is inserted into a half period of each video frame period and output to the panel drive circuit 18 (S27).

  When it is determined that the difference amount calculated in step S23 is smaller than the first threshold value (S24: NO), the control unit 10 determines whether the difference amount is larger than the second threshold value stored in advance in its own ROM. Is determined (S28). When the control unit 10 determines that the difference amount is larger than the second threshold value (S28: YES), the control unit 10 notifies the black signal generation circuit 14 and the LCD controller 15 to that effect, and the black signal generation circuit 14 causes the black signal generation circuit 14 to obtain a predetermined black value. A black frame composed of a black signal of a signal level is generated (S29) and output to the LCD controller 15. Next, the controller 10 causes the LCD controller 15 to output a backlight control signal having an H level during the half of each video frame period to the backlight control circuit 16 (S30), and the black frame generated in step S29. Are inserted into the 1/3 period of each video frame period with respect to the video frame input from the video signal processing circuit 12 and output to the panel drive circuit 18 (S31).

  When the control unit 10 determines that the difference amount calculated in step S23 is smaller than the second threshold (S28: NO), the control unit 10 notifies the black signal generation circuit 14 and the LCD controller 15 to that effect, and the black signal generation circuit 14 In step S32, the LCD controller 15 outputs a backlight control signal whose H level is 1/5 of each video frame period to the backlight control circuit 16 without generating a black frame (S32). The video frame input from is directly output to the panel drive circuit 18 (S33). As a result, the backlight control circuit 16 turns on the backlight 17 based on the backlight control signal input from the LCD controller 15, and the panel drive circuit 18 displays the video based on the video frame input from the LCD controller 15. The image is displayed on the liquid crystal display panel 19.

  The control unit 10 determines whether or not the display of all the video frames of the video signal input to the video signal processing circuit 12 is finished (S34), and if the display of all the video frames is not finished. If it is determined (S34: NO), the process returns to step S23, and the above-described processes of steps S23 to S34 are repeated until the display of all the video frames is completed. Further, when the control unit 10 determines that the display of all the video frames has been completed (S34: YES), the control unit 10 ends the above-described processing.

  In the second embodiment described above, the video based on the video signal should be inserted within the corresponding video frame period depending on whether the video is a fast moving video, a normal video, or a substantially still image. The liquid crystal television 1 configured to change the black signal insertion period has been described. However, the liquid crystal television 1 may be configured such that the insertion period of the black frame inserted for each video frame period is constant, and the number of black pixels included in the inserted black frame is changed.

  Specifically, when the video based on the video signal is a fast moving video, the black pixel (for example, pixel value is 255) has a large number of pixels (for example, 50% of the pixels included in the black frame). When a frame is inserted in each video frame period and the video based on the video signal is a normal moving image, a black frame with a moderate number of black pixels (for example, 33% of the pixels included in the black frame) May be inserted in each video frame period, and when the video based on the video signal is substantially a still image, a black frame may not be inserted. In addition, the liquid crystal television 1 in the above-described second embodiment can be applied with a modification similar to the modification described in the first embodiment.

  In the first and second embodiments described above, the black signal level of the black signal to be inserted in each video frame period or the black frame insertion period is changed based on the amount of difference between two video frames moving back and forth in time series. In addition, the liquid crystal television 1 having a configuration in which the luminance of the backlight 17 is changed is described. However, the luminance of the backlight 17 may not be controlled, and only the black signal level of the black signal to be inserted in each video frame period or the insertion period of the black frame may be changed. In this case, the liquid crystal television 1 As described above, the present invention is not limited to a device that displays an image on the liquid crystal display panel 19, and the present invention can be applied to, for example, a projector. If the luminance control of the backlight 17 is not performed, it is not possible to reduce the luminance change in the display screen that may occur with the insertion of the black frame, but by performing the pseudo impulse type display control. Therefore, it is possible to improve the motion blur and display a video with excellent motion characteristics.

FIG. 2 is a block diagram illustrating a configuration example of a main part of the liquid crystal television of Embodiment 1. 3 is a waveform diagram of a video signal in the liquid crystal television of Embodiment 1. FIG. 6 is a flowchart illustrating a procedure of black signal insertion processing in the liquid crystal television according to the first embodiment. 6 is a flowchart illustrating a procedure of black signal insertion processing in the liquid crystal television according to the first embodiment. 6 is a waveform diagram of a video signal in the liquid crystal television of Embodiment 2. FIG. 10 is a flowchart illustrating a procedure of black signal insertion processing in the liquid crystal television according to the second embodiment. 10 is a flowchart illustrating a procedure of black signal insertion processing in the liquid crystal television according to the second embodiment.

Explanation of symbols

1 LCD TV (video display device)
10 Control Unit 13 Motion Detection Circuit (Difference Calculation Unit)
14 Black signal generation circuit (specific means)
15 LCD controller (black insertion means)
16 Backlight control circuit (drive means)
17 Backlight 19 Liquid crystal display panel (display means)

Claims (9)

In a video display device comprising black insertion means for inserting a black signal within each video frame period of a video signal composed of a plurality of video frames, and display means for displaying the video signal into which the black insertion means has inserted the black signal,
A difference calculating means for calculating a difference amount between the preceding and succeeding video frames in time series;
Specifying means for specifying the black signal level of the black signal inserted by the black insertion means according to the difference amount calculated by the difference calculation means;
The video display device, wherein the black insertion means is configured to insert a black signal of a black signal level specified by the specifying means.   The specifying means is configured to specify the black signal level of the black signal inserted by the black inserting means as high / low according to the difference amount calculated by the difference calculating means. The video display device according to claim 1, wherein A liquid crystal display panel;
A backlight disposed on the back of the liquid crystal display panel;
3. The video display device according to claim 1, further comprising: a driving unit configured to control the luminance of the backlight to high / low according to high / low of the black signal level specified by the specifying unit. . In a video display device comprising black insertion means for inserting a black signal within each video frame period of a video signal composed of a plurality of video frames, and display means for displaying the video signal into which the black insertion means has inserted the black signal,
A difference calculating means for calculating a difference amount between the preceding and succeeding video frames in time series;
Specifying means for specifying an insertion period of a black signal inserted by the black insertion means for each video frame period according to the difference amount calculated by the difference calculation means;
The video display device, wherein the black insertion unit is configured to insert a black signal of an insertion period specified by the specifying unit.   The specifying means is configured to specify the black signal insertion period inserted by the black insertion means as long / short according to the difference amount calculated by the difference calculating means. The video display device according to claim 4. A liquid crystal display panel;
A backlight disposed on the back of the liquid crystal display panel;
6. The video display device according to claim 4, further comprising: a driving unit configured to control the luminance of the backlight to be high / low according to the length / shortness of the insertion period specified by the specifying unit. In a video display device comprising black insertion means for inserting a black signal within each video frame period of a video signal composed of a plurality of video frames, and display means for displaying the video signal into which the black insertion means has inserted the black signal,
The black insertion means is configured to insert a black signal frame including a plurality of black pixels in each video frame period,
A difference calculating means for calculating a difference amount between the preceding and succeeding video frames in time series;
Specifying means for specifying the number of black pixels included in the black signal frame inserted by the black insertion means according to the difference amount calculated by the difference calculation means;
The video display device, wherein the black insertion means is configured to insert a black signal frame including black pixels of the number of pixels specified by the specifying means.   The specifying unit is configured to specify the number of black pixels included in the black signal frame inserted by the black insertion unit to be large / small according to the difference amount calculated by the difference calculation unit. The video display apparatus according to claim 7, wherein the video display apparatus is provided. A liquid crystal display panel;
A backlight disposed on the back of the liquid crystal display panel;
The video display device according to claim 7, further comprising: a driving unit that controls the luminance of the backlight to be high / low according to the number of pixels specified by the specifying unit.

Images