JP5208035B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device, and more particularly to a technique for preventing image quality deterioration.

  A liquid crystal display (LCD) has features such as high-definition display, low power consumption, and space saving, and its replacement from CRT has been accelerated in various applications such as computer monitors and television display devices. Yes. However, since the LCD has insufficient image quality in moving image display compared to the CRT, improvement in moving image quality is required.

  One problem with LCD moving image display is that the LCD is hold-type drive that continues to display until it is rewritten with the image information of the next frame. In a TFT-LCD that is often used as an LCD, electric charges stored by applying an electric field to liquid crystals are held at a relatively high rate until the next electric field is applied. Therefore, each pixel of the LCD continues to be displayed until it is rewritten by applying an electric field based on pixel information of the next frame. On the other hand, in a CRT display device that performs display by scanning an electron beam to emit phosphors, the light emission of each pixel is in an impulse shape. Accordingly, the LCD has a lower time frequency characteristic of image display light than a CRT, and the spatial frequency characteristic is also lowered accordingly, resulting in motion blur of moving picture display.

  As a conventional technique for dealing with this problem, Patent Document 1 discloses that the frame rate of an input video signal is converted to N times, and black display is performed in at least one vertical display period within one frame period of the input video signal. By inserting a gain adjustment signal in which the amplitude of a signal or video signal is adjusted, a means for improving motion blur by bringing it closer to an impulse response is disclosed.

JP 2002-215111 A

  However, in Patent Document 1, since the image signal and the gain adjustment signal obtained by adjusting the amplitude of the black signal or video signal are switched and output in units of the vertical display period, the change from the image signal to the black signal or the gain adjustment signal is performed. In addition, in any of the changes from the black signal or the gain adjustment signal to the image signal, the movement of the change is visually recognized. As a result, the effect of improving the motion blur is reduced.

  That is, even when either the black display signal or the gain adjustment signal in which the amplitude of the video signal is adjusted is inserted, the image quality is deteriorated, and as a result, the quality of the moving image display is lowered as compared with the impulse response such as the CRT. was there.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a liquid crystal display device capable of preventing image quality deterioration of moving image display.

In the liquid crystal display device according to the present invention, the frame rate of the signal based on the first video signal sequentially input is multiplied by n (n is an integer of 2 or more). A frame rate conversion unit that repeatedly outputs the second video signal n times to the liquid crystal display panel; and a backlight control unit that controls the timing of turning on and off the backlight light source. Turns off the backlight light source at a first timing corresponding to the second video signal for the first time, turns on the backlight light source at a second timing corresponding to the second video signal for the second time and thereafter , The first timing includes a period from the start of response of the liquid crystal display panel to the completion of response to the second video signal for the first time, and the second timing. Including a period after the completion of the response, and the backlight light source includes an LED backlight, a cold cathode ray tube (CCFL), or a hot cathode ray tube (HCFL), and is input from a first video signal that is sequentially input. A synchronization detection unit that detects a vertical synchronization signal; the backlight control unit performs the control using the input vertical synchronization signal as a trigger; and the frame rate conversion unit determines a frame rate of the input vertical synchronization signal an output vertical synchronization signal multiplied by n, and the backlight control unit performs the control using the output vertical synchronization signal as a trigger, and further includes a light guide plate disposed on a back surface of the liquid crystal display panel, The light source is a plurality of edge lights disposed on the edge of the liquid crystal display panel, and the plurality of edge lights are independently independent of each other. And the first timing is a period from a response start to a response completion of each section of the liquid crystal display panel corresponding to each of the plurality of edge lights with respect to the second video signal for the first time. wherein, as said signal based on the first image signal sequentially inputted, the frame rate of the first video signal to double, and the interpolation picture signals interpolated signal between adjacent frames is sandwiched at its every other frame Is further output to the frame rate converter, and the frame rate converter uses the interpolated video signal as the signal based on the first video signal.

In the liquid crystal display device according to the present invention, the frame rate of the signal based on the first video signal sequentially input is multiplied by n (n is an integer of 2 or more). A frame rate conversion unit that repeatedly outputs the second video signal n times to the liquid crystal display panel; and a backlight control unit that controls the timing of turning on and off the backlight light source. Turns off the backlight light source at a first timing corresponding to the second video signal for the first time, turns on the backlight light source at a second timing corresponding to the second video signal for the second time and thereafter , The first timing includes a period from the start of response of the liquid crystal display panel to the completion of response to the second video signal for the first time, and the second timing. Including a period after the completion of the response, and the backlight light source includes an LED backlight, a cold cathode ray tube (CCFL), or a hot cathode ray tube (HCFL), and is input from a first video signal that is sequentially input. A synchronization detection unit that detects a vertical synchronization signal; the backlight control unit performs the control using the input vertical synchronization signal as a trigger; and the frame rate conversion unit determines a frame rate of the input vertical synchronization signal an output vertical synchronization signal multiplied by n, and the backlight control unit performs the control using the output vertical synchronization signal as a trigger, and further includes a light guide plate disposed on a back surface of the liquid crystal display panel, The light source is a plurality of edge lights disposed on the edge of the liquid crystal display panel, and the plurality of edge lights are independently independent of each other. And the first timing is a period from a response start to a response completion of each section of the liquid crystal display panel corresponding to each of the plurality of edge lights with respect to the second video signal for the first time. wherein, as said signal based on the first image signal sequentially inputted, the frame rate of the first video signal to double, and the interpolation picture signals interpolated signal between adjacent frames is sandwiched at its every other frame Is output to the frame rate converter, and the frame rate converter uses the interpolated video signal as the signal based on the first video signal, so that the liquid crystal in the liquid crystal display panel at the first timing. The change in the liquid crystal is recognized as motion blur without remaining as an afterimage in the retina of the viewer's eyes. Therefore, image quality deterioration can be prevented.

FIG. 3 is a main part block diagram of the liquid crystal display device according to the first embodiment. 4 is a timing chart for explaining each operation in the liquid crystal display device according to the first embodiment. FIG. 3 is a main part block diagram of the liquid crystal display device according to the first embodiment. FIG. 6 is a main part block diagram of a liquid crystal display device according to a second embodiment. 6 is a timing chart illustrating each operation in the liquid crystal display device according to the second embodiment. 6 is a schematic diagram of a light guide plate in a liquid crystal display device according to Embodiment 3. FIG. 6 is a schematic diagram of a light guide plate in a liquid crystal display device according to Embodiment 3. FIG. 6 is a schematic diagram of a light guide plate in a liquid crystal display device according to Embodiment 3. FIG. 12 is a timing chart illustrating each operation in the liquid crystal display device according to the third embodiment. 6 is a schematic diagram of a light guide plate in a liquid crystal display device according to Embodiment 4. FIG. 6 is a schematic diagram of a light guide plate in a liquid crystal display device according to Embodiment 4. FIG. 6 is a schematic diagram of a light guide plate in a liquid crystal display device according to Embodiment 4. FIG. 6 is a timing chart for explaining each operation in the liquid crystal display device according to the fourth embodiment. FIG. 10 is a schematic diagram of a direct backlight in a liquid crystal display device according to a fifth embodiment. 10 is a timing chart for explaining each operation in the liquid crystal display device according to the fifth embodiment. FIG. 10 is a main part block diagram of a liquid crystal display device according to a sixth embodiment. 16 is a timing chart for explaining operations in the liquid crystal display device according to the sixth embodiment. FIG. 10 is a principal block diagram of a liquid crystal display device according to a seventh embodiment. FIG. 10 is a configuration diagram of a liquid crystal display panel in a liquid crystal display device according to a seventh embodiment. 18 is a timing chart for explaining operations in the liquid crystal display device according to the seventh embodiment. FIG. 10 is a main part block diagram of a liquid crystal display device according to an eighth embodiment. 12 is a timing chart for explaining operations in a liquid crystal display device according to an eighth embodiment. FIG. 20 is a main part block diagram of a liquid crystal display device according to a ninth embodiment. FIG. 38 is a main part block diagram of the liquid crystal display device according to the tenth embodiment. FIG. 38 is a main part block diagram of the liquid crystal display device according to the tenth embodiment. FIG. 29 is a principal block diagram illustrating another configuration example of the liquid crystal display device according to the tenth embodiment.

<A. Embodiment 1>
<A-1. Configuration>
Hereinafter, the first embodiment of the present invention will be described in detail with reference to FIG. 1 and FIG. FIG. 1 is a main block diagram of the liquid crystal display device according to the first embodiment, and FIG. 2 is a timing chart for explaining operations in the liquid crystal display device according to the first embodiment.

  As shown in FIG. 1, the liquid crystal display device according to the first embodiment is detected by a synchronization detection unit 1 that detects the frequency of an input synchronization signal corresponding to an input first video signal, and a synchronization detection unit 1. The CPU 4 outputs a control signal based on the synchronized signal and controls the operation of each unit, the frame memory unit 2 that stores an image of the first video signal in units of frames, for example, one frame, the frame memory unit 2 and the first A video signal and a second video signal to be described later are transmitted and received, and a second video signal obtained by converting the frame rate of the first video signal sequentially input based on a control signal from the CPU 4 to n times is repeatedly output n times. The frame rate conversion unit 3, the liquid crystal display panel 8 to which the second video signal output from the frame rate conversion unit 3 is input, and the backlight light source 7 based on the control signal from the CPU 4. And a backlight duty and phase control unit 5 for controlling the timing of turning off, a backlight drive unit 6 for driving the backlight light source 7 based on an output signal from the backlight duty and phase control unit 5, and a backlight drive unit 6 And a backlight light source 7 for turning on and off the backlight of the liquid crystal display panel 8 based on the signal from.

  Note that the backlight light source 7 can include any of an LED backlight, a cold cathode ray tube (CCFL), and a hot cathode ray tube (HCFL).

  Further, the backlight light source 7 may be an EL (Electro Luminescence).

<A-2. Operation>
Here, a case where the first video signal (60 Hz) as an input video signal is time-axis compressed to twice (120 Hz) will be described. The CPU 4 generates a control signal for frame rate conversion based on the vertical synchronization signal and the horizontal synchronization signal detected by the synchronization detection unit 1.

  Based on the control signal from the CPU 4, the frame rate conversion unit 3 stores an image of one frame of the first video signal (60 Hz) in the frame memory unit 2 as shown in FIG. As shown in 2 (b), the video signal is repeatedly read out as the second video signal in the first field and the second field at twice the frame rate (120 Hz), so that the vertical period is compressed to 1/120 seconds. The second video signal thus output is continuously output to the liquid crystal display panel 8.

  That is, the frame rate conversion unit 3 functions as a frame rate conversion unit according to the present invention, and a first video signal (input video) having a first display period (1/60 seconds) input to the liquid crystal display device. Signal) is time-compressed to 1/2 times, and each frame is read twice as the first field and the second field, thereby reading the second display period (1/120) which is ½ times the first display period. Second video signal having a second).

  The liquid crystal display panel 8 operates based on the second video signal that is time-axis-compressed with a vertical period of 1/120 seconds input from the frame rate conversion unit 3. In FIG. 2B, the same second video signal generated and read out by the frame rate conversion unit 3 is input to the liquid crystal display panel 8 as the video signal of the first field and the second field in each frame. Accordingly, the operation of the liquid crystal in the liquid crystal display panel 8 is as follows. As shown in FIG. 2C, the liquid crystal responds according to the second video signal input in the first field, and the first field in the second field. Since the same second video signal is input, the liquid crystal does not respond substantially and keeps the state as it is.

  For the sake of clarity, an example in which the entire frame is a white signal in an odd frame and the entire black signal in an even frame will be described as an example. As shown in FIG. 2C, liquid crystal is input to the video signal input in the first field of the first frame. Responds to white, and the liquid crystal maintains the white state as it is for the video signal input of the second field of the first frame. Further, the liquid crystal responds to the video signal input of the first field of the next second frame so as to be black, and the liquid crystal remains black for the video signal input of the second field of the second frame. Hold. This operation is repeated for the third frame, the fourth frame, and so on.

  In the liquid crystal display panel 8, the liquid crystal in the first line at the top of the display is driven from the vicinity of the start of each field, and the drive proceeds to the lower liquid crystal in sequence, and the final line at the bottom of the display is near the end of each field. The liquid crystal is driven, one image is completed for each field, and the image is displayed on the liquid crystal display panel 8. That is, there is a time difference between the liquid crystal on the first line and the liquid crystal on the last line as shown in FIG. Further, as a characteristic of the liquid crystal, the liquid crystal cannot complete the response instantaneously, and it takes several milliseconds to complete the response.

  That is, the liquid crystal somewhere on the liquid crystal display panel 8 responds, that is, changes as a single image from the start of response of the liquid crystal in the first line of each first field to the end of response of the liquid crystal in the last line. Become.

  If the backlight is lit while the liquid crystal is responding, that is, changing, the change remains as an afterimage on the retina of the eye, and this afterimage causes motion blur to cause image quality degradation. In other words, to prevent motion blur from being recognized and causing image quality degradation, the backlight should be turned off while the liquid crystal is responding or changing, and the backlight should be turned on after the response of the liquid crystal is completed. Good.

  That is, the period from the start of the liquid crystal response of the first line of the first field, which is the first second video signal area of each frame in FIG. 2C, to the end of the liquid crystal response of the last line of the first field. The backlight light source is turned off (first timing), and the response of the last line liquid crystal in the first field of each frame is completed until the response of the first line liquid crystal in the first field of the next frame starts. If the backlight is turned on in the second video signal area after the second time (second timing), the response of the liquid crystal, that is, the change does not remain as an afterimage in the retina of the eye, that is, the motion blur is eliminated and the image quality is deteriorated. Can be prevented.

  The CPU 4 determines the timing of turning on and off the backlight light source based on the input vertical synchronization signal detected by the synchronization detection unit 1 and outputs a control signal to the backlight duty and phase control unit 5.

  The backlight duty and phase control unit 5 operates according to a control signal from the CPU 4 and controls the backlight driving unit 6.

  The backlight drive unit 6 drives the backlight light source 7 to be turned on or off according to the control signal from the backlight duty and phase control unit 5, and the backlight light source 7 is optimally set so as not to cause motion blur finally. Turns on and off repeatedly according to the controlled timing.

  In the present embodiment, the CPU 4 controls to turn on or off the backlight light source 7 based on the synchronization signal detected by the synchronization detection unit 1 (as a trigger), but is generated by the frame rate conversion unit 3. The CPU 4 may control whether the backlight is turned on or off based on an output vertical synchronization signal obtained by driving the liquid crystal display panel 8 to an n-fold frequency (as a trigger).

  Similarly, based on a DE (Data Enable) signal generated by the frame rate conversion unit 3 and driving the liquid crystal display panel 8, the CPU 4 may control turning on or off of the backlight.

<A-3. Effect>
According to the first embodiment of the present invention, in the liquid crystal display device, the frame rate of the liquid crystal display panel 8, the backlight source 7 of the liquid crystal display panel 8, and the first video signal that is sequentially input is multiplied by n (n Is a frame rate conversion unit 3 that repeatedly outputs the second video signal n times each to the liquid crystal display panel 8, and a backlight control unit that controls the timing of turning on and off the backlight light source 7. A backlight duty and phase control unit 5, and the backlight duty and phase control unit 5 turns off the backlight light source 7 at the first timing corresponding to the second video signal for the first time, and the second and subsequent times. By turning on the backlight source 7 at the second timing corresponding to the second video signal, the liquid crystal in the liquid crystal display panel 8 at the first timing is displayed. The backlight source 7 can be turned off while the response, that is, changing, and the backlight source 7 can be turned on while the liquid crystal is responding, that is, not changing, at the second timing. Does not remain as an afterimage on the retina of the viewer's eyes and is not recognized as motion blur, thereby preventing image quality deterioration.

  Further, compared with other impulse generating means such as black display signal insertion, it is possible to make it closer to the original impulse type drive, thereby preventing image quality deterioration.

  According to the first embodiment of the present invention, in the liquid crystal display device, the first timing corresponding to the first second video signal starts the response of the liquid crystal display panel 8 to the first second video signal. The second timing corresponding to the second video signal includes the period after the completion of the response, so that the liquid crystal in the liquid crystal display panel 8 which is the first timing is responding, that is, changing. The backlight light source 7 can be turned off and the backlight light source 7 can be turned on while the liquid crystal at the second timing is not responding, that is, not changing. Therefore, it is not recognized as motion blur, so that it is possible to prevent image quality deterioration.

  Further, according to the first embodiment of the present invention, in the liquid crystal display device, the backlight source 7 includes any one of an LED backlight, a cold cathode ray tube (CCFL), and a hot cathode ray tube (HCFL). The backlight light source 7 is turned on and off at the first timing corresponding to the second video signal for the first time and the second timing corresponding to the second video signal for the second and subsequent times, and the liquid crystal changes in the liquid crystal display panel 8. Does not remain as an afterimage on the retina of the viewer's eyes and is not recognized as motion blur, thereby preventing image quality deterioration.

  Further, according to the first embodiment of the present invention, in the liquid crystal display device, the backlight light source 7 is an EL (Electro Luminescence), so that the backlight light source 7 is turned on and off for the first time. Control is performed at the first timing corresponding to the signal and the second timing corresponding to the second and subsequent second video signals, and the liquid crystal change in the liquid crystal display panel 8 moves without remaining as an afterimage in the viewer's eye retina. Since it is not recognized as blur, image quality deterioration can be prevented.

  According to the first embodiment of the present invention, the liquid crystal display device further includes the synchronization detection unit 1 that detects the input vertical synchronization signal from the sequentially input first video signal, and is a backlight control unit. The light duty and phase control unit 5 controls the timing of turning on and off the backlight light source 7 using the input vertical synchronization signal as a trigger, so that the change in the liquid crystal in the liquid crystal display panel 8 becomes an afterimage on the retina of the viewer's eyes. Since it does not remain and is not recognized as motion blur, image quality deterioration can be prevented.

  According to the first embodiment of the present invention, in the liquid crystal display device, the frame rate conversion unit 3 outputs the output vertical synchronization signal obtained by multiplying the frame rate of the input vertical synchronization signal by n times, and the backlight control unit The backlight duty and phase controller 5 controls the timing of turning on and off the backlight light source 7 using the output vertical synchronization signal as a trigger, so that the change in the liquid crystal in the liquid crystal display panel 8 is the retina of the viewer's eyes. Therefore, it is not recognized as motion blur, so that it is possible to prevent image quality deterioration.

  Further, according to the first embodiment of the present invention, in the liquid crystal display device, the frame rate conversion unit 3 generates a DE (Data Enable) signal for driving the liquid crystal display panel 8, and is a backlight control unit. The light duty and phase control unit 5 controls the timing of turning on and off the backlight light source 7 using the DE signal as a trigger, so that the change of the liquid crystal in the liquid crystal display panel 8 remains as an afterimage in the retina of the viewer's eyes. Since it is not recognized as motion blur, image quality deterioration can be prevented.

  In the first embodiment, the CPU 4 is configured to control the operation of each unit based on the synchronization signal detected by the synchronization detection unit 1, but as shown in FIG. 3, the synchronization signal detected by the synchronization detection unit 1 On the basis of the above, each unit may operate without the CPU 4.

<B. Second Embodiment>
<B-1. Configuration>
Next, Embodiment 2 of the present invention will be described with reference to FIGS. 4 and 5. FIG.

  4 creates an interpolation signal (frame 2'3 ') from adjacent frames of the first video signal sequentially input in the configuration of FIG. 1, and double-speed conversion (conversion to 120Hz when the input is 60Hz). Then, an interpolation circuit 19 for adding an interpolated video signal in which the interpolated signal is inserted between the preceding and following frames (a frame obtained by double-speed conversion of the first video signal) to the frame rate converting unit 3 is added.

<B-2. Operation>
The frame rate conversion unit 3 further converts the interpolated video signal after the double speed conversion including the interpolation signal generated by the interpolation circuit 19 into a frame rate of double (240 Hz in this case), and converts the time-compressed video signal to the first video signal. It is repeatedly output to the liquid crystal display panel 8 as a video signal of the first field and the second field.

  The subsequent operation is the same as that of the first embodiment, and a timing chart thereof is shown in FIG.

  As can be seen from FIG. 5, instead of the first video signal (input video signal) of 60 Hz, the interpolation signal generated by the interpolation circuit 19 between the video signal whose frame rate is converted to 120 Hz and the adjacent video signal. (For example, the second frame 2′3 ′ in FIG. 5A) is sandwiched and output to the frame rate conversion unit 3 as an interpolated video signal. The frame rate conversion unit 3 uses a 240 Hz video signal obtained by further double-converting the interpolated video signal as the second video signal. The liquid crystal response in the liquid crystal display panel 8 and the control timing of the backlight source 7 in accordance with the response are the same as those in the first embodiment.

<B-3. Effect>
According to the second embodiment of the present invention, in the liquid crystal display device, the frame rate of the first video signal is doubled and the interpolated signal between adjacent frames is used instead of the sequentially input first video signal. It further includes an interpolation circuit 19 that outputs the interpolated video signal sandwiched every other frame to the frame rate conversion unit 3, and the frame rate conversion unit 3 uses the interpolated video signal instead of the first video signal to perform interpolation. It is possible to obtain image quality that is smooth movement by a signal and has no movement blur.

<C. Embodiment 3>
<C-1. Configuration>
Next, Embodiment 3 of the present invention will be described with reference to FIGS.

  Generally, an edge light backlight system uses a light guide plate to transmit light emitted from edge light (upper part) and edge light (lower part) provided at the upper and lower edges of a liquid crystal display panel and convert it into surface emission. It is provided on the back of the liquid crystal display panel.

  6A and 6B are schematic views of the light guide plate in the liquid crystal display device according to the third embodiment. FIG. 6A is a view seen from the liquid crystal display panel side, and FIG. Is a view from the side.

  As shown in FIGS. 6A and 6B, a light guide plate 11a is disposed on the back of a liquid crystal display panel 8 (not shown), and a plurality of edge lights (upper, (Lower part) 9 and 10 are arranged. The edge lights 9, 10 can be turned on and off independently.

  As shown in FIG. 6C, the light guide plate 11a attenuates as the light transmittance goes to the center line, so that the light from the edge light (upper part) 9 does not pass below the center line. The light from the (lower part) 10 is designed not to be transmitted upward from the center line. That is, there are sections corresponding to the edge lights 9 and 10, respectively.

  At the same time, as shown in FIG. 6 (d), the light emission amount in the direction of the liquid crystal display panel is designed to have uniform characteristics as a whole when combined with the compensation film.

<C-2. Operation>
If the light guide plate 11a having such characteristics is used, the light emitted from the edge light (upper part) 9 does not reach the lower part of the center line of the liquid crystal display panel, so that the liquid crystal below the center line of the liquid crystal display part is responding. Even if the edge light (upper part) 9 is turned on, the light emitted from the edge light (upper part) 9 does not affect the lower part of the center line of the liquid crystal display panel, and further, the light emitted from the edge light (lower part) 10 does not affect the liquid crystal display panel. Therefore, even if the edge light (lower part) 10 is turned on when the liquid crystal above the center line of the liquid crystal display unit is responding, the light emitted from the edge light (lower part) 10 is displayed on the liquid crystal display. Does not affect the area above the center line of the panel.

  Therefore, at this time, even if the backlight light source 7 is turned on and off as shown in FIG. 9, if the timing of turning on and off is set in the backlight region corresponding to each edge light (upper and lower). The liquid crystal response in the corresponding area, that is, the liquid crystal is not lit during the change period. That is, as shown in FIG. 9C, the response start of each section of the liquid crystal display panel 8 corresponding to each of the edge lights 9 and 10 with respect to the first second video signal (first line liquid crystal response, intermediate portion liquid crystal response). Since the corresponding edge lights 9 and 10 are extinguished during the period from the start of each of the final line liquid crystal responses to the completion of the response, the liquid crystals in the respective sections (upper and lower) change during the period. Each of the edge lights 9 and 10 is turned off at the first timing.

  Therefore, as can be seen by comparing the backlight lighting period of FIG. 9 and the backlight lighting period of FIG. 2, the lighting time can be made longer, that is, a state with higher luminance can be obtained. That is, by setting the period from the response start to the response completion of each section of the liquid crystal display panel 8 corresponding to each of the edge lights 9 and 10, the lighting time can be made longer than in the case shown in FIG. That is, a higher brightness state can be obtained.

  Further, the same effect can be expected even if a shape having the characteristic that the light transmission characteristic is attenuated in the region defining the partition (FIG. 7C) as shown in FIG. 7B is used for the light guide plate 11b.

  Further, the light guide plate 11c shown in FIGS. 8 (b) and 8 (c) has a boundary near the center and is devised so that light from one of the divided upper and lower portions does not reach the light guide plate on the opposite half surface. The same effect can be expected.

  In the case of the light guide plate 11c as shown in FIG. 8B, the compensation film can have an effect of suppressing color unevenness and luminance unevenness at the boundary portion between the divided regions.

<C-3. Effect>
According to Embodiment 3 of the present invention, the liquid crystal display device further includes a light guide plate 11 disposed on the back surface of the liquid crystal display panel 8, and the backlight light sources 7 are disposed above and below the liquid crystal display panel 8. The plurality of edge lights 9, 10 can be turned off and on independently, and the first timing corresponding to the second video signal for the first time is the second time for the first time. By including the period from the response start of each section of the liquid crystal display panel 8 corresponding to each of the plurality of edge lights 9 and 10 to the video signal, the response of the liquid crystal display panel 8 corresponding to each of the edge lights 9 and 10 is included. By setting the period from the start of response to the completion of response in each section, the lighting time can be made longer than in the case shown in FIG. It is possible to obtain. Accordingly, it is possible to suppress a decrease in luminance due to turning off.

  Further, according to the third embodiment of the present invention, in the liquid crystal display device, the light guide plates 11a and 11b are attenuated in a predetermined region in which the light transmission characteristics define the partition, so that the other partitions are influenced by light. The edge lights 9 and 10 corresponding to the respective sections can be turned on and off, and the lighting time can be lengthened, so that a decrease in luminance can be suppressed.

  Further, according to the third embodiment of the present invention, in the liquid crystal display device, the light guide plate 11c is divided into a plurality of regions corresponding to the partitions, so that the other partitions are not affected by light, The edge lights 9 and 10 corresponding to the respective sections can be turned on and off, and the lighting time can be extended, so that a decrease in luminance can be suppressed.

  Further, according to the third embodiment of the present invention, in the liquid crystal display device, the light guide plate 11c does not transmit light between the divided regions, so that the other sections are not affected by light, and The edge lights 9 and 10 corresponding to the sections can be turned on and off, and the lighting time can be extended, so that a decrease in luminance can be suppressed.

  Further, according to the third embodiment of the present invention, in the liquid crystal display device, the light guide plate 11c further includes a compensation film that suppresses color unevenness and brightness unevenness at the boundary portion of the divided regions, whereby the liquid crystal The amount of light radiation in the display panel 8 can be made uniform throughout.

<D. Embodiment 4>
<D-1. Configuration>
Next, Embodiment 4 of the present invention will be described with reference to FIGS.

  FIGS. 10A and 10B are schematic views of a light guide plate in the liquid crystal display device according to the fourth embodiment. Edge lights (sides) 12 are provided on one or both sides of the left and right edges of the liquid crystal display panel. FIG. 10A is a view seen from the liquid crystal display panel side, and FIG. 10B is a view seen from the lateral direction. As shown in FIG. 10C, the light guide plate 11d is designed such that the light transmittance is attenuated toward the boundary, and the light from each edge light (side) 12 is not transmitted through the boundary. That is, there is a section corresponding to each of the edge lights 12. In addition, each section can be turned on and off independently.

  At the same time, as shown in FIG. 10 (d), the light emission amount in the direction of the liquid crystal display panel is designed to have uniform characteristics as a whole when combined with the compensation film. Here, the case where it divides into three areas is shown as an example.

  At the same time, as shown in FIG. 10 (d), the light emission amount in the direction of the liquid crystal display panel is designed to have uniform characteristics as a whole when combined with the compensation film.

<D-2. Operation>
If the light guide plate 11d having such characteristics is used, the light emitted from each edge light (side) 12 does not reach the portion other than the region of the liquid crystal display panel, so that the liquid crystal of the liquid crystal display portion other than the region responds. Even if the edge light (side) 12 in the area is turned on during the operation, the light emitted from the edge light (side) 12 in the area does not affect the liquid crystal display portion in the other area.

  At this time, even if the lighting and extinguishing timings of the backlight light source 7 are set as shown in FIG. 13, the backlight light source 7 is not lit during the response of the liquid crystal, that is, the changing period. That is, as shown in FIG. 13C, the response start of the liquid crystal display panel 8 corresponding to each section of the edge light 12 with respect to the first second video signal (first-line liquid crystal response, 1/3 part) Since each of the edge lights 12 is turned off during the period from the start of the liquid crystal response, the 2/3 liquid crystal response, and the final line liquid crystal response) to the completion of the response, the edge light 12 is turned off during the period in which the liquid crystal in each section is changing. Each section of the light 12 is turned off at each first timing.

  That is, as can be seen by comparing the backlight lighting period in FIG. 13 and the backlight lighting period in FIG. 2, the lighting time can be made longer, that is, a higher luminance state can be obtained. That is, by setting the period from the response start to the response completion of each section of the liquid crystal display panel 8 corresponding to each of the edge lights 12, the lighting time can be made longer than in the case shown in FIG. 2 of the first embodiment. That is, a state with higher luminance can be obtained.

  Further, the same effect can be expected even when a shape having a characteristic that the light transmission characteristic is attenuated in a region defining the division (FIG. 11C) as shown in FIG. 11B is used for the light guide plate 11e.

  In addition, the light guide plate shown in FIGS. 12B and 12C, which has a boundary between each edge light and is designed so that the light of the light does not reach other areas, can be expected to have the same effect.

  In the case of the light guide plate 11f as shown in FIG. 12B, the compensation film can have an effect of suppressing color unevenness and luminance unevenness at the boundary portion of the divided regions.

<D-3. Effect>
According to the fourth embodiment of the present invention, the liquid crystal display device further includes the light guide plate 11 disposed on the back surface of the liquid crystal display panel 8, and the backlight light source 7 is disposed on the edge of the liquid crystal display panel 8. The plurality of edge lights 12 can be turned off and on independently, and the first timing corresponding to the first second video signal corresponds to the first second video signal. By including the period from the start of response of each section of the liquid crystal display panel 8 corresponding to each of the plurality of edge lights 12 to the completion of response, the response of each section of the liquid crystal display panel 8 corresponding to each of the edge lights 12 By setting the period from the start to the completion of response, the lighting time can be made longer than in the case shown in FIG. Door can be. Accordingly, it is possible to suppress a decrease in luminance due to turning off.

  Further, according to the fourth embodiment of the present invention, in the liquid crystal display device, the light guide plates 11d and 11e attenuate the light transmission characteristics in a predetermined region that defines the partition, thereby affecting the other partitions by light. The edge light 12 corresponding to each section can be turned on and off, and the lighting time can be extended, so that a decrease in luminance can be suppressed.

  Further, according to the fourth embodiment of the present invention, in the liquid crystal display device, the light guide plate 11f is divided into a plurality of regions corresponding to the partitions, so that the other partitions are not affected by light, The edge light 12 corresponding to each section can be turned on and off, and the lighting time can be lengthened, so that a decrease in luminance can be suppressed.

  Further, according to the fourth embodiment of the present invention, in the liquid crystal display device, the light guide plate 11f does not transmit light between the divided regions, so that the other sections are not affected by light, and Since the edge light 12 corresponding to the section can be turned on and off, and the lighting time can be lengthened, a decrease in luminance can be suppressed.

  Further, according to the fourth embodiment of the present invention, in the liquid crystal display device, the light guide plate 11f further includes a compensation film for suppressing color unevenness and luminance unevenness at the boundary portion of the divided regions, so that the liquid crystal The amount of light radiation in the display panel 8 can be made uniform throughout.

  A combination with the upper and lower edge lights 9 and 10 in the third embodiment is also possible.

  In addition, here, as an example, a case where the light source is divided into three regions is shown, but the same applies to a case where the light source is divided into a plurality of regions, and the backlight light source 7 is turned on as the number of divided regions increases. The period becomes longer and the effect of increasing the brightness is increased.

<E. Embodiment 5>
<E-1. Configuration>
Next, a fifth embodiment of the present invention will be described with reference to FIG. 14 and FIG.

  Generally, in the direct backlight system, a backlight light source as a light source is provided on the back surface of the liquid crystal display panel 8.

  FIG. 14 is a schematic diagram of a direct backlight in the liquid crystal display device according to the fifth embodiment. FIG. 14 is a view of the liquid crystal display panel 8 as viewed from the front, and the direct backlight 13 is a backlight light source disposed on the back of the liquid crystal display panel 8. Here, as an example, there is shown a case where the direct backlight 13 is arranged in four areas and each has a corresponding section.

<E-2. Operation>
Next, the operation will be described. Each direct backlight 13 is controlled to be turned on and off independently according to the response of the liquid crystal, that is, the changing timing. A timing chart at this time is shown in FIG.

  At this time, even if the lighting and extinguishing timings of the direct backlight 13 are set as shown in FIG. 15, if the lighting and extinguishing timings are set for the direct backlight 13 in each area, the response of the liquid crystal in the corresponding area, that is, It does not light up while the liquid crystal is changing. That is, as shown in FIG. 15C, the response start of the liquid crystal display panel 8 corresponding to each area of the direct backlight 13 with respect to the first second video signal (first line liquid crystal response, 1/4 part liquid crystal). Response, 2/4 part liquid crystal response, 3/4 part liquid crystal response, and final line liquid crystal response (from the start of each) to the completion of the response, each corresponding direct backlight 13 is turned off, so the liquid crystal in each section Each of the direct backlights 13 is extinguished at the first timing during the period in which is changed.

  That is, as can be seen by comparing the backlight lighting period of FIG. 15 and the backlight lighting period of FIG. 2, the first timing (that is, the turn-off time) corresponding to the first second video signal is assigned to each of the direct backlights 13. By setting the period from the response start to the response completion of each section of the corresponding liquid crystal display panel 8, the lighting time can be made longer than that in the case of FIG. 2, that is, a higher luminance state can be obtained.

<E-3. Effect>
According to Embodiment 5 of the present invention, in the liquid crystal display device, the backlight light source 7 is the plurality of direct backlights 13 disposed on the back surface of the liquid crystal display panel 8, and the plurality of direct backlights 13 are: The liquid crystal display panel 8 corresponding to each of the plurality of direct backlights 13 corresponding to the first second video signal can be turned off and on independently. Embodiment 1 includes the period from the start of response to the completion of response in each section, thereby setting the period from the start of response to the end of response in each section of the liquid crystal display panel 8 corresponding to each of the direct backlights 13. As shown in FIG. 2, the lighting time can be further increased, that is, a higher brightness state can be obtained. Accordingly, it is possible to suppress a decrease in luminance due to turning off.

  Further, in the fifth embodiment, a case where the area is divided into four areas is shown as an example, but the same applies to the case where the area is divided into two or more areas. As the number of divided areas increases, The lighting period of the backlight light source 7 becomes longer, and the effect of increasing the brightness is improved.

<F. Embodiment 6>
<F-1. Configuration>
Next, a sixth embodiment of the present invention will be described with reference to FIGS. 16 and 17.

  FIG. 16 is a block diagram according to the liquid crystal display device of the fifth embodiment. The second video signal output from the frame rate conversion unit 3 between the frame rate conversion unit 3 and the liquid crystal display panel 8 of FIG. A high-speed video signal writing unit 14 for reading and writing the second video signal at a higher speed than usual, that is, at a speed higher than one vertical synchronizing signal period is provided on the liquid crystal display panel 8. For example, when the second video signal is written to the liquid crystal display panel 8, the video signal high-speed writing unit 14 can write the second video signal to the liquid crystal display panel 8 at a high speed by operating at a high speed.

<F-2. Operation>
FIG. 17 is a timing chart when the second video signal is written on the liquid crystal display panel 8 at high speed by the video signal high-speed writing unit 14. As shown in this timing chart, when the second video signal is written to the liquid crystal display panel 8 at a speed higher than one vertical synchronizing signal period (FIG. 17B), the blanking period of each field is lengthened. Can do. This extended blanking period is applied to the lighting time of the backlight light source 7, that is, as shown in FIG. 17C, the response start time of the final line liquid crystal response is accelerated, so that the response completion time is also accelerated. Since the start time (see the backlight light source driving waveform) can be shortened, the luminance can be increased.

<F-3. Effect>
According to the sixth embodiment of the present invention, in the liquid crystal display device, the video signal high-speed writing that writes the second video signal output from the frame rate conversion unit 3 to the liquid crystal display panel 8 faster than one vertical synchronizing signal period. By further including the unit 14, the blanking period that is longer in one vertical synchronization signal period can be used for the lighting time of the backlight light source 7, so that the luminance due to turning off can be suppressed.

<G. Embodiment 7>
<G-1. Configuration>
Next, Embodiment 7 of the present invention will be described with reference to FIG. 18, FIG. 19, and FIG.

  FIG. 18 is a block diagram according to the liquid crystal display device of the seventh embodiment, in which video signals of odd lines and even lines can be read simultaneously from the frame rate conversion unit 3, and FIG. 19 shows the present embodiment. 7 is a configuration diagram of the liquid crystal display panel 8 according to the liquid crystal display device 7, in which the gate driver area is grouped into a gate driver 15a and a gate driver 15b, and writing is performed in the corresponding areas. Is provided.

  The gate driver 15a and the source driver 16a correspond to the video signal writing of the odd lines of the liquid crystal display panel 8, and the gate driver 15b and the source driver 16b correspond to the video signal writing of the even lines of the liquid crystal display panel 8, respectively. The second video signal is simultaneously written into the.

<G-2. Operation>
With this configuration, as shown in the timing chart of FIG. 20, the second video signal can be written to the liquid crystal display panel 8 at twice the normal speed by writing on the odd and even lines. (FIG. 20B), the blanking period of each field can be lengthened. The longer blanking period is applied to the lighting time of the backlight light source 7, that is, as shown in FIG. 20C, the response start time of the final line liquid crystal response is accelerated and the response completion time is also accelerated. Since the start time (see the backlight light source driving waveform) can be shortened, the luminance can be increased.

<G-3. Effect>
According to Embodiment 7 of the present invention, in the liquid crystal display device, the liquid crystal display panel 8 is provided in a region corresponding to each of the plurality of gate drivers 15a and 15b grouped and the plurality of gate drivers 15a and 15b. The plurality of source drivers 16a and 16b for writing the second video signal are further provided, and the plurality of source drivers 16a and 16b simultaneously apply the second video signal corresponding to the area to the area corresponding to each group of the gate drivers. By writing, for example, if the odd and even groups are written at the same time, the second video signal is written at twice the normal speed, and the blanking period that is longer by that amount is used as the lighting time of the backlight light source 7. Since it can be applied, it is possible to suppress a decrease in luminance due to light extinction.

  Here, as an example, the case of dividing into two regions of odd lines and even lines is shown, but the same applies to the case of dividing into four regions for every four lines or more, and as the number of divided regions increases, The lighting period of the light source 7 becomes longer, and the effect of increasing the brightness is increased.

  Although the case where video signals are sequentially written from the upper part of the liquid crystal display panel 8 is shown here, the same effect can be expected when the gate driver and the source driver are separately written in the upper and lower areas of the liquid crystal display panel 8. In addition, when the liquid crystal display panel is divided into three areas, ie, the upper part, the central part, and the lower part of the liquid crystal display panel, or when the liquid crystal display panel is divided into more areas, the effect of increasing the brightness is enhanced.

<H. Eighth Embodiment>
<H-1. Configuration>
Next, an eighth embodiment of the present invention will be described with reference to FIGS.

  FIG. 21 is a block diagram according to the liquid crystal display device of the eighth embodiment, and a further current control unit 17 is supplied to the backlight light source 7 and controls a current value for driving the backlight light source 7. The backlight light source 7 has a high luminance when the current value controlled by the current control unit 17 is large, and the luminance is low when the current value is small.

<H-2. Operation>
That is, as shown in the timing chart of FIG. 22, control is performed to increase the value of the current for driving the backlight light source 7 during the lighting period when lighting and extinguishing are repeated (during intermittent lighting in FIG. 22C). If the current is referred to), it is possible to suppress the luminance from being lowered by intermittent lighting, and the luminance can be increased. Other operations are the same as those in the first embodiment.

<H-3. Effect>
According to the eighth embodiment of the present invention, in the liquid crystal display device, the current control for controlling the current value supplied to the backlight light source 7 in accordance with the second timing corresponding to the second and subsequent second video signals. By further providing the unit 17, if the current control unit 17 performs control so that the value of the current for driving the backlight light source 7 is increased during the lighting period, it is possible to suppress a decrease in luminance due to intermittent lighting. And the brightness can be increased.

<I. Ninth Embodiment>
<I-1. Configuration>
Next, Embodiment 9 of the present invention will be described with reference to FIG.

  FIG. 23 is a block diagram according to the liquid crystal display device of the ninth embodiment, in which the backlight source 7 is divided into a backlight source 7a and a backlight source 7b.

  Here, the backlight light source 7a is driven during normal backlight operation without intermittent lighting and during intermittent lighting operation, and the backlight light source 7b is not driven during normal backlight operation without intermittent lighting, and during intermittent lighting operation. It is set to drive only.

<I-2. Operation>
With such a configuration, the number of backlights that are turned on at the time of intermittent lighting increases, so that it is possible to suppress a decrease in luminance due to intermittent lighting, and the luminance can be increased.

<I-3. Effect>
According to Embodiment 9 of the present invention, in the liquid crystal display device, a plurality of backlight light sources 7 (backlight light sources 7a and 7b) are provided, and the backlight control unit 6 applies the second and subsequent second video signals. By switching the number of backlight light sources to be turned on according to the corresponding second timing, the number of backlights to be turned on at the time of intermittent lighting increases, so that it is possible to suppress the brightness from being lowered by intermittent lighting, Can be high.

  Further, during normal backlight operation, the backlight light source 7a and the backlight light source 7b are alternately turned on, for example, alternately turned on every frame, so that the lifetime (or deterioration) of each backlight can be made equal. It can also be expected to extend the life of the backlight.

  Although the case where the backlight is divided into two is shown here, the same effect can be obtained even if the backlight is divided into three or more.

<J. Embodiment 10>
<J-1. Configuration>
Next, Embodiment 10 of the present invention will be described with reference to FIGS.

  FIG. 24 is a block diagram according to the liquid crystal display device of the tenth embodiment. The liquid crystal display panel 8 includes an overdrive unit 18, and the overdrive unit 18 displays a video signal written on the liquid crystal display panel 8. A voltage larger than the actual gradation change is applied to the liquid crystal for a moment (overdrive) to improve the response speed of the intermediate gradation.

  When overdrive is applied to a large area, the response of the liquid crystal becomes faster. However, if the overdrive is applied too much, the edge of the display image may be shaded or colored, resulting in image degradation. The response speed cannot be minimized.

<J-2. Operation>
However, in the liquid crystal display device of the tenth embodiment, the period from the start of the liquid crystal response of the first line of the first field of each frame at the first timing to the end of the liquid crystal response of the last line of the first field is backed up. Since the light source 7 is turned off (FIG. 25 (c)), even if an extremely large overdrive is applied to the first field image, the liquid crystal display panel does not display an image during this period. It will not be done. That is, overdrive can be applied to minimize the response of the liquid crystal in the first field.

  FIG. 25 is a timing chart at this time. When overdrive is performed so that the response time of the liquid crystal is minimized, the time required for the response of each liquid crystal in the liquid crystal display panel 8 is shortened. It can be seen that the completion time becomes earlier, the lighting start time of the backlight light source 7 becomes earlier, and the lighting time of the backlight light source 7 becomes longer. Therefore, a reduction in luminance can be prevented.

  Although the case where the overdrive unit 18 is provided in the liquid crystal display panel 8 is shown here, as shown in FIG. 26, the overdrive unit 18a is provided in the front stage of the liquid crystal display panel 8, and the overdrive processing is performed here. The same effect can be obtained by adding to the video signal and then outputting to the liquid crystal display panel 8.

<J-3. Effect>
According to the tenth embodiment of the present invention, in the liquid crystal display device, the liquid crystal display panel 8 overdrives the liquid crystal of the panel by applying a voltage higher than the voltage corresponding to the second video signal. The overdrive is performed at the first timing corresponding to the first second video signal, so that the overdrive can be applied so that the response time of the liquid crystal is minimized. Since the lighting time becomes longer, it is possible to suppress a decrease in luminance due to turning off at the first timing.

  According to the tenth embodiment of the present invention, the liquid crystal display device further includes an overdrive unit 18a that derives a voltage larger than the corresponding voltage and overdrives the second video signal, and the overdrive includes: Since it is performed at the first timing corresponding to the second video signal for the first time, the overdrive can be applied so that the response time of the liquid crystal is minimized, and the lighting time of the backlight light source 7 is increased accordingly. In addition, it is possible to suppress a decrease in luminance associated with turning off at the first timing.

  DESCRIPTION OF SYMBOLS 1 Sync detection part, 2 frame memory part, 3 frame rate conversion part, 4 CPU, 5 backlight duty and phase control part, 6 backlight drive part, 7 backlight light source, 8 liquid crystal display panel, 9 edge light (upper part) 10 edge light (lower part), 11, 11a, 11b, 11c light guide plate, 12 edge light (side), 13 direct backlight, 14 video signal high-speed writing unit, 15 gate driver, 16 source driver, 17 current control unit, 18 Overdrive section, 19 Interpolation circuit.

Claims (10)

A liquid crystal display panel;
A backlight source of the liquid crystal display panel;
A frame rate conversion unit that outputs a second video signal obtained by multiplying a frame rate of a signal based on the first video signal sequentially input by n times (n is an integer of 2 or more) to the liquid crystal display panel repeatedly n times each;
A backlight control unit that controls the timing of turning on and off the backlight light source;
With
The backlight control unit turns off the backlight light source at a first timing corresponding to the second video signal for the first time, and the backlight light source at a second timing corresponding to the second video signal for the second time and thereafter. Lights up
The first timing includes a period from a response start of the liquid crystal display panel to a response completion with respect to the second video signal for the first time,
The second timing includes a period after completion of the response,
The backlight light source includes an LED backlight, a cold cathode ray tube (CCFL), or a hot cathode ray tube (HCFL),
A synchronization detection unit for detecting an input vertical synchronization signal from the sequentially input first video signal;
The backlight control unit performs the control using the input vertical synchronization signal as a trigger,
The frame rate conversion unit outputs an output vertical synchronization signal obtained by multiplying a frame rate of the input vertical synchronization signal by the n times,
The backlight control unit performs the control using the output vertical synchronization signal as a trigger,
A light guide plate disposed on the back surface of the liquid crystal display panel;
The backlight light source is a plurality of edge lights arranged on the edge of the liquid crystal display panel,
The plurality of edge lights can be turned off and turned on independently,
The first timing includes a period from a response start to a response completion of each section of the liquid crystal display panel corresponding to each of the plurality of edge lights with respect to the second video signal for the first time ,
As the signal based on the first video signal sequentially input, an interpolated video signal in which the frame rate of the first video signal is doubled and an interpolated signal between adjacent frames is sandwiched every other frame is used. It further includes an interpolation circuit that outputs to the frame rate conversion unit,
The frame rate conversion unit uses the interpolated video signal as the signal based on the first video signal .
Liquid crystal display device. The light guide plate is attenuated in a predetermined region whose light transmission characteristics define the section ;
The liquid crystal display device according to claim 1. The light guide plate is divided into a plurality of regions corresponding to the sections .
The liquid crystal display device according to claim 1. The light guide plate does not transmit light between the divided regions .
The liquid crystal display device according to claim 3 . The light guide plate further includes a compensation film for suppressing color unevenness and brightness unevenness at a boundary portion of the divided regions ,
The liquid crystal display device according to claim 3 or 4 . A video signal high-speed writing unit that writes the second video signal output from the frame rate conversion unit to the liquid crystal display panel faster than one vertical synchronization signal period ;
The liquid crystal display device according to claim 1. The liquid crystal display panel further includes a plurality of grouped gate drivers, and a plurality of source drivers for writing the second video signal in a region corresponding to each of the plurality of gate drivers,
The plurality of source drivers simultaneously write the second video signal corresponding to the area in an area corresponding to each group of the gate drivers .
The liquid crystal display device according to any one of claims 1-6. A current control unit for controlling a current value supplied to the backlight light source according to the second timing ;
The liquid crystal display device according to claim 1. The liquid crystal display panel includes an overdrive unit that overdrives the liquid crystal of the panel by applying a voltage larger than a voltage corresponding to the second video signal,
The overdrive is performed at the first timing .
The liquid crystal display device according to claim 1. An overdrive unit for deriving and overdriving a voltage larger than the corresponding voltage with respect to the second video signal;
The overdrive is performed at the first timing .
The liquid crystal display device according to claim 1.