JP2013029563A - Display device and display method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device capable of reducing delay time.SOLUTION: The display device includes: a frame rate converter; a liquid crystal display part that displays an image after frame rate conversion; a backlight that intermittently emits a lay of light; and a backlight controller that has plural operation modes in which light emitting timing of the backlight is different from each other. The frame rate converter performs the frame rate conversion by generating plural sub frame images same as the frame image in one operation mode. The backlight controller sets the center of one light emitting period of the backlight in the one operation mode before the center of a display period when the liquid crystal display part displays the plural sub frame images.

Description

  The present disclosure relates to a display device using a liquid crystal display element and a display method thereof.

  In recent years, in display devices, replacement of CRT (Cathode Ray Tube) display devices with liquid crystal display devices has been progressing. Since the liquid crystal display device can be made thinner than a CRT display device, it is easy to realize space saving, and since the power consumption is low, there is a merit from the viewpoint of ecology.

  The liquid crystal display device is a so-called hold-type display device in which the state of pixels is continuously held for one frame. Therefore, when an observer observes a moving object displayed on such a display device, a so-called hold blur occurs and the viewer feels that the image quality has deteriorated. In order to improve the hold blur, a method of intermittently lighting the backlight (backlight blinking) is often used (for example, Patent Document 1). Specifically, for example, a pixel signal is written to the liquid crystal display element with the backlight turned off, and the backlight is turned on after the liquid crystal almost responds in the second half of the frame period. Thereby, the liquid crystal display device performs an impulse-type display such as a CRT and can reduce hold blur.

  Incidentally, one of video signal processing for improving image quality in a display device is frame rate conversion using frame interpolation. This frame rate conversion is to generate an interpolated frame obtained by interpolating adjacent frames in the input video, and add the interpolated frame to the input video (for example, Patent Document 1). As a result, the displayed image becomes a smoother image, and, for example, when the liquid crystal display device is used, the above-described hold blur is reduced and the image quality is improved.

JP 2011-13558 A

  Incidentally, it is generally desired for display devices to shorten the delay time from when a video signal is supplied until the video is actually displayed. In this case, for example, it is conceivable that the frame rate conversion is performed by repeating the same frame image instead of performing the frame rate conversion by a frame interpolation process that generally requires time. However, in some applications such as a game application in which a display object moves at high speed, further reduction in delay time is desired.

  The present disclosure has been made in view of such a problem, and an object thereof is to provide a display device and a display method capable of shortening a delay time from when a video signal is supplied to when an image is actually displayed. There is to do.

  The first display device of the present disclosure includes a frame rate conversion unit, a liquid crystal display unit, a backlight, and a backlight control unit. The liquid crystal display unit displays the frame rate converted video. The backlight emits light intermittently. The backlight control unit has a plurality of operation modes having different backlight emission timings.

  The second display device of the present disclosure includes a frame rate conversion unit, a liquid crystal display unit, a backlight, and a backlight control unit. The frame rate conversion unit performs frame rate conversion by generating a plurality of subframe images that are the same as the frame image. The liquid crystal display unit displays a video signal whose frame rate has been converted. The backlight emits light intermittently. In one operation mode, the backlight control unit switches the backlight so that the center of one emission period of the backlight is before the center of the display period in which the liquid crystal display unit displays a plurality of subframe images. It is something to control.

  In the display method of the present disclosure, a backlight whose light emission timing can be changed emits light intermittently, and a frame rate converted image is displayed on a liquid crystal display unit.

  In the first display device and display method of the present disclosure, the backlight emits light intermittently, and the sub-frame image generated by the frame rate conversion is repeatedly displayed on the liquid crystal display unit a plurality of times. The backlight emission timing is configured to be changeable.

  In the second display device of the present disclosure, the backlight emits light intermittently, and the sub-frame image generated by the frame rate conversion is repeatedly displayed on the liquid crystal display unit a plurality of times. The center of the light emission period of the backlight is controlled to be before the center of the display period in a predetermined operation mode.

  According to the first display device and the display method of the present disclosure, since the backlight emission timing can be changed, the delay time from when the video signal is supplied to when the video is actually displayed is shortened. Can do.

  According to the second display device of the present disclosure, since the center of the light emission period of the backlight comes before the center of the display period, the video signal is supplied until the video is actually displayed. The delay time can be shortened.

3 is a block diagram illustrating a configuration example of a display device according to a first embodiment of the present disclosure. FIG. FIG. 2 is a block diagram illustrating a configuration example of a display driving unit illustrated in FIG. 1. FIG. 3 is a circuit diagram illustrating a configuration example of a pixel illustrated in FIG. 2. FIG. 2 is a plan view illustrating a configuration example of a backlight illustrated in FIG. 1. FIG. 3 is a timing waveform diagram illustrating an operation example of the display device illustrated in FIG. 1. FIG. 10 is a timing waveform chart illustrating another operation example of the display device illustrated in FIG. 1. FIG. 10 is a timing waveform chart illustrating another operation example of the display device illustrated in FIG. 1. FIG. 10 is a timing waveform diagram illustrating an operation example of a display device according to a modification of the first embodiment. FIG. 10 is a timing waveform diagram illustrating an operation example of a display device according to another modification of the first embodiment. FIG. 10 is a timing waveform diagram illustrating another operation example of the display device according to another modification of the first embodiment. It is a top view showing the example of 1 structure of the backlight which concerns on the other modification of 1st Embodiment. FIG. 10 is a timing waveform diagram illustrating an operation example of a display device according to another modification of the first embodiment. FIG. 10 is a timing waveform diagram illustrating another operation example of the display device according to another modification of the first embodiment. FIG. 10 is a timing waveform diagram illustrating another operation example of the display device according to another modification of the first embodiment. It is a block diagram showing the example of 1 structure of the display apparatus which concerns on 2nd Embodiment. It is a histogram explaining the brightness histogram signal shown in FIG. FIG. 16 is a timing waveform diagram illustrating an operation example of the display device illustrated in FIG. 15. FIG. 16 is a timing waveform chart illustrating another operation example of the display device illustrated in FIG. 15. 16 is a flowchart illustrating an operation example of the backlight driving unit illustrated in FIG. 15. FIG. 16 is a timing waveform chart illustrating another operation example of the backlight driving unit illustrated in FIG. 15. FIG. 10 is a timing waveform diagram illustrating an operation example of a display device according to a modification of the second embodiment.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order.
1. First Embodiment 2. FIG. Second embodiment

<1. First Embodiment>
[Configuration example]
(Overall configuration example)
FIG. 1 illustrates a configuration example of the display device 1 according to the first embodiment. The display device 1 is a liquid crystal display device composed of liquid crystal display elements. The display method according to the embodiment of the present disclosure is embodied by the present embodiment, and will be described together.

  The display device 1 includes a video signal processing unit 11, a frame rate conversion unit 12, a display driving unit 20, a liquid crystal display unit 30, a board setting unit 13, a backlight driving unit 14, and a backlight 40. ing.

  The video signal processing unit 11 performs video signal processing such as contrast enhancement, edge enhancement, interlace / progressive conversion, and scaling (image size conversion) on the video signal Sdisp and outputs it as a video signal Sdisp1.

  The frame rate conversion unit 12 performs frame rate conversion based on the video signal Sdisp1 supplied from the video signal processing unit 11 and outputs it as the video signal Sdisp2. In this example, the frame rate conversion is performed by converting the frame rate by four times from 60 frames per second to 240 frames per second. At this time, the frame rate conversion unit 12 performs frame rate conversion by repeating the same frame image without performing frame interpolation processing. That is, since the frame rate conversion unit 12 does not perform time-consuming frame interpolation processing, frame rate conversion can be realized in a short processing time. The frame rate conversion unit 12 also has a function of supplying the synchronization signal Ssync to the backlight driving unit 14.

  The display drive unit 20 drives the liquid crystal display unit 30 based on the video signal Sdisp2 supplied from the frame rate conversion unit 12. The liquid crystal display unit 30 is a display unit configured by a liquid crystal display element, and performs display by modulating light emitted from the backlight 40. In this example, the liquid crystal display unit 30 is a liquid crystal display panel compatible with so-called quadruple speed driving.

  FIG. 2 illustrates an example of a block diagram of the display driving unit 20 and the liquid crystal display unit 30. The display driving unit 20 includes a timing control unit 21, a gate driver 22, and a data driver 23. The timing control unit 21 controls the driving timing of the gate driver 22 and the data driver 23 and supplies the video signal Sdisp2 supplied from the frame rate conversion unit 12 to the data driver 23 as the video signal Sdisp3. The gate driver 22 performs line-sequential scanning by sequentially selecting the pixels Pix in the liquid crystal display unit 30 for each row according to timing control by the timing control unit 21. The data driver 23 supplies a pixel signal based on the video signal Sdisp3 to each pixel Pix of the liquid crystal display unit 30. Specifically, the data driver 23 performs a D / A (digital / analog) conversion based on the video signal Sdisp3, thereby generating a pixel signal that is an analog signal and supplying the pixel signal to each pixel Pix. Yes.

  The liquid crystal display unit 30 is obtained by enclosing a liquid crystal material between two transparent substrates made of, for example, glass. A transparent electrode made of, for example, ITO (Indium Tin Oxide) or the like is formed on a portion of the transparent substrate facing the liquid crystal material, and constitutes a pixel Pix together with the liquid crystal material. As shown in FIG. 2, the liquid crystal display unit 30 has pixels Pix arranged in a matrix.

  FIG. 3 illustrates an example of a circuit diagram of the pixel Pix. The pixel Pix includes a TFT (Thin Film Transistor) element Tr, a liquid crystal element LC, and a storage capacitor element Cs. The TFT element Tr is configured by, for example, a MOS-FET (Metal Oxide Semiconductor-Field Effect Transistor), the gate is connected to the gate line GCL, the source is connected to the data line SGL, and the drain is the liquid crystal element LC. One end and one end of the storage capacitor element Cs are connected. The liquid crystal element LC has one end connected to the drain of the TFT element Tr and the other end grounded. The storage capacitor element Cs has one end connected to the drain of the TFT element Tr and the other end connected to the storage capacitor line CSL. The gate line GCL is connected to the gate driver 22, and the data line SGL is connected to the data driver 23.

  The mode setting unit 13 is for the user to set the operation mode of the display device 1. Specifically, the mode setting unit 13 displays a list of operation modes by, for example, a user interface (UI) using OSD (On Screen Display) and the user selects an operation mode from the list. It has become. In this example, an image quality priority mode M1 and a delay time priority mode M2 are prepared as operation modes. As will be described later, the image quality priority mode M1 and the delay time priority mode M2 have different backlight emission timings. The mode setting unit 13 supplies an operation mode signal Smode indicating the operation mode selected by the user to the backlight driving unit 14.

  The backlight drive unit 14 drives the backlight 40 based on the synchronization signal Ssync supplied from the frame rate conversion unit 12 and the operation mode signal Smode supplied from the mode setting unit 13.

  The backlight 40 emits light (blinks) intermittently based on a drive signal supplied from the backlight drive unit 14 and emits the light to the liquid crystal display unit 30.

  FIG. 4 shows a configuration example of the backlight 40. The backlight 40 is a so-called line scan type backlight, and includes a plurality (eight in this example) of light emitting units BL1 to BL8 arranged in parallel in the line sequential scanning direction of the liquid crystal display unit 30. A plurality of LEDs (Light Emitting Diodes) 42 are arranged in parallel in each of the light emitting units BL1 to BL8. The light emitting portions BL1 to BL8 are not limited to this configuration, and may be configured by, for example, CCFL (Cold Cathode Fluorescent Lamp).

  With this configuration, the backlight driving unit 14 can control the light emission of the backlight 40 independently for each of the regions Z1 to Z8 corresponding to the light emitting units BL1 to BL8. Thereby, in the display device 1, display is performed at independent timing for each of the corresponding regions Z <b> 1 to Z <b> 8 on the display surface of the liquid crystal display unit 30.

  Here, the delay time priority mode M2 corresponds to a specific example of “one operation mode” in the present disclosure. The image quality priority mode M1 corresponds to a specific example of “another operation mode” in the present disclosure.

[Operation and Action]
Subsequently, the operation and action of the display device 1 of the present embodiment will be described.

(Overview of overall operation)
First, an overall operation overview of the display device 1 will be described with reference to FIG. The video signal processing unit 11 performs predetermined video signal processing on the video signal Sdisp, and outputs the result as the video signal Sdisp1. The frame rate conversion unit 12 performs frame rate conversion on the video signal Sdisp1, outputs it as the video signal Sdisp2, and generates a synchronization signal Ssync synchronized with the video signal Sdisp2. The display driving unit 20 drives the liquid crystal display unit 30 based on the video signal Sdisp2. The mode setting unit 13 sets an operation mode of the display device 1 based on an instruction from the user, and generates an operation mode signal Smode. The backlight drive unit 14 drives the backlight 40 based on the synchronization signal Ssync and the operation mode signal Smode. The backlight 40 emits light based on the drive signal supplied from the backlight drive unit 14 and emits the light to the liquid crystal display unit 30. The liquid crystal display unit 30 performs display by modulating the light emitted from the backlight 40.

(Detailed operation)
Next, detailed operations of the display device 1 in the image quality priority mode M1 and the delay time priority mode M2 will be described below.

  FIG. 5 shows a timing chart of the display operation in the image quality priority mode M1, (A) shows the operation of the liquid crystal display unit 30, and (B) shows the operation of the backlight 40. 5A indicates the scanning position of the liquid crystal display unit 30 in the line sequential scanning direction. In FIG. 5A, for example, “F (n)” indicates a state in which the liquid crystal display unit 30 displays the nth frame image F (n), and “F (n + 1)” indicates the liquid crystal. The state where the display unit 30 is displaying the (n + 1) th frame image F (n + 1) is shown. In FIG. 5B, “ON” indicates that the light emitting portions BL1 to BL8 of the backlight 40 are turned on, and “OFF” indicates that the light emitting portions BL1 to BL8 of the backlight 40 are turned off. It shows the state.

  In the display device 1, for example, a frame image is supplied at a period T0 of 16.7 [msec] (= 1/60 [Hz]), and the frame rate conversion unit 12 converts the frame rate to four times, and 4.2. Each frame image (subframe image) subjected to frame rate conversion is output at a cycle T1 of [msec] (= 1/60 [Hz] / 4). Then, the liquid crystal display unit 30 displays each frame image after the frame rate conversion, and the backlight 40 emits light in synchronization with the display. The details will be described below.

  First, in the period of timing t0 to t1, the liquid crystal display unit 30 performs line sequential scanning from the top to the bottom based on the drive signal supplied from the display drive unit 20, and the frame image F (n) Display is performed (FIG. 5A). Then, the light emitting portions BL1 to BL8 of the backlight 40 are turned off in synchronization with the line sequential scanning (FIG. 5B).

  Similarly, the liquid crystal display unit 30 changes from the uppermost part to the lowermost part based on the drive signal supplied from the display drive part 20 in the period from timing t1 to t2, the period from timing t2 to t3, and the period from timing t3 to t4. Line sequential scanning is performed, and the display of the frame image F (n) is repeatedly performed (FIG. 5A). That is, in this example, the display of the frame image F (n) is repeated four times during the period from timing t0 to t4. The light emitting portions BL1 to BL8 of the backlight 40 are turned on in synchronization with the fourth line sequential scanning (FIG. 5B). Specifically, for example, the light emitting unit BL1 starts lighting at a timing when a predetermined time td1 has elapsed from the timing when the corresponding region Z1 on the display surface of the liquid crystal display unit 30 is scanned, and the next line sequential in the region Z1. The lighting is continued until the scanning is performed (lighting time ton) (FIG. 5B). Similarly, the light emitting unit BL2 starts lighting at a timing when a predetermined time td1 has elapsed from the timing when the corresponding region Z2 on the display surface of the liquid crystal display unit 30 is scanned, and the next line sequential scanning is performed in the region Z2. The lighting is continued for a period of time (lighting time ton) (FIG. 5B). The same applies to the light emitting portions BL3 to BL8.

  Thereafter, the liquid crystal display unit 30 similarly starts displaying the next frame image F (n + 1) by line-sequential scanning after timing t4 (FIG. 5A), and each light emission of the backlight 40. The portions BL1 to BL8 are turned off in synchronization with the first line sequential scanning (FIG. 5B).

  In the image quality priority mode M1, the light emitting portions BL1 to BL8 of the backlight 40 are respectively lit in synchronization with the fourth line sequential scanning. That is, since the liquid crystal of the liquid crystal display unit 30 starts to respond by the first line sequential scanning, it is in a sufficiently responsive state at the time of the fourth line sequential scanning, and each of the light emitting units BL1 to BL8. Is turned on after the liquid crystals in the corresponding regions Z1 to Z8 in the liquid crystal display unit 30 have sufficiently responded. As a result, the observer does not see a transient display on the liquid crystal display unit 30 and can therefore reduce image quality degradation.

  6A and 6B are timing charts of the display operation in the delay time priority mode M2. FIG. 6A shows the operation of the liquid crystal display unit 30, and FIG. 6B shows the operation of the backlight 40.

  First, during the period from timing t10 to t11, the liquid crystal display unit 30 performs line sequential scanning from the top to the bottom based on the drive signal supplied from the display drive unit 20 to generate the frame image F (n). Display is performed (FIG. 6A). Then, the light emitting portions BL1 to BL8 of the backlight 40 are turned on in synchronization with the line sequential scanning (FIG. 6B). Specifically, for example, the light emitting unit BL1 starts lighting at a timing t18 when a predetermined time td2 has elapsed from the timing when the corresponding region Z1 on the display surface of the liquid crystal display unit 30 is scanned, and during the lighting time ton. It continues to be turned on and then turned off at timing t19 (FIG. 6B). Similarly, the light emitting unit BL2 starts lighting at a timing when a predetermined time td2 has elapsed from the timing at which the corresponding area Z2 on the display surface of the liquid crystal display unit 30 is scanned, and continues to light for the lighting time ton. The light is turned off (FIG. 6B). The same applies to the light emitting portions BL3 to BL8. At this time, the light emission amount A (product of the lighting time ton and the luminance I) of each of the light emitting units BL1 to BL8 is set to be equal in the image quality priority mode M1 and the delay time priority mode M2. Thereby, for example, even when the observer changes the operation mode while observing the video, the possibility that the observer feels unnatural can be reduced.

  Then, the liquid crystal display unit 30 moves from the top to the bottom based on the drive signal supplied from the display drive unit 20 in the period of timing t11 to t12, the period of timing t12 to t13, and the period of timing t13 to t14. Then, line sequential scanning is performed to repeatedly display the frame image F (n) (FIG. 6A).

  Thereafter, the liquid crystal display unit 30 similarly starts displaying the next frame image F (n + 1) by line sequential scanning after timing t14 (FIG. 6A).

  In the delay time priority mode M2, the light emitting units BL1 to BL8 of the backlight 40 are respectively lit in synchronization with the first line sequential scanning. That is, for example, in each of the light emitting units BL1 to BL8, the liquid crystal has almost responded from timing t18 (timing when time td2 has elapsed from timing t10) in which the liquid crystal in the corresponding region Z1 to Z8 of the liquid crystal display unit 30 is responding. Lights up during a period until timing t19 (immediately before timing t11). As described above, since the backlight 40 is turned on at an earlier timing than the image quality priority mode M1, the time (delay time) from when the video signal is supplied to the display device 1 until actual display is performed is shortened. Can do.

  FIG. 7 shows in more detail the light emission timing of each of the light emitting units BL1 to BL8 in the delay time priority mode M2, (A) shows the operation of the liquid crystal display unit 30, and (B) shows the backlight 40. (C) shows the operation of each of the light emitting portions BL1 to BL8. Here, the oblique broken lines in FIGS. 7B and 7C represent line sequential scanning in the regions Z1 to Z8 of the liquid crystal display unit 30 corresponding to the light emitting units BL1 to BL8.

  As shown in FIG. 7, in the delay time priority mode M2, the light emitting units BL1 to BL8 have the display periods P1 to P8 of the corresponding regions Z1 to Z8 of the liquid crystal display unit 30 at the centers tc1 to tc8. Are set in the first half period P1A to P8A. More specifically, in this example, the centers tc1 to tc8 of each light emission period are set to the first half of the first half periods P1A to P8A. Here, during the display periods P1 to P8, the next frame image (for example, the frame image F) from the first scan of a certain frame image (for example, the frame image F (n)) in each of the regions Z1 to Z8 of the liquid crystal display unit 30. (n + 1)) period until the first scan. Specifically, for example, in the display period P1, the first line sequential scan for the frame image F (n) starts from the timing ts1 when the center in the vertical direction of the region Z1 of the liquid crystal display unit 30 is reached. The first line-sequential scanning of the frame image F (n + 1) ends at the timing te1 when it reaches the center in the vertical direction of the region Z1 of the liquid crystal display unit 30.

  As described above, in the display device 1, in the delay time priority mode M2, the centers tc1 to tc8 of the light emitting units BL1 to BL8 are set to the first half periods P1A to P8A of the display periods P1 to P8. Therefore, the display delay time can be shortened. Thereby, for example, in a game application in which a display object moves at high speed, the user can perform a timely game operation.

[effect]
As described above, in the present embodiment, since the lighting timing of the backlight is made variable, a display operation with a high degree of freedom can be performed.

  In the present embodiment, in the delay time priority mode M2, since the center of the light emission period is set within the first half of the display period, the display delay time can be shortened.

[Modification 1-1]
In the above embodiment, in the delay time priority mode M2, the time td2 is set so that the centers tc1 to tc8 of the light emission period are in the first half of the periods P1A to P8A in the first half of the periods P1 to P8. For example, as illustrated in FIG. 8, the time td2 may be set to be the second half of the periods P1A to P8A. For example, in the delay time priority mode M2 shown in FIG. 6, the backlight 40 is lit even during a period in which the liquid crystal is in the middle of response, so the observer sees a transient display on the liquid crystal display unit 30 and prioritizes image quality. There is a possibility that the image quality is deteriorated as compared with the mode M1. In such a case, as shown in FIG. 8, the time td2 may be adjusted to such an extent that there is no problem in the application.

[Modification 1-2]
In the above-described embodiment, the frame rate conversion unit 12 converts the frame rate to four times. However, the frame rate is not limited to this, and instead, for example, the frame rate may be converted to two times. . Details will be described below.

  FIG. 10 is a timing chart of the display operation in the image quality priority mode M1 of the display device 1B according to this modification. FIG. 10 (A) shows the operation of the liquid crystal display unit 30, and FIG. Shows the operation. In this example, a liquid crystal display panel compatible with so-called double speed driving can be used as the liquid crystal display unit 30.

  In the display device 1B, for example, a frame image is supplied at a period T0 of 16.7 [msec] (= 1/60 [Hz]), and the frame rate conversion unit 12B according to this modification converts the frame rate to double. Then, each frame image subjected to frame rate conversion is output at a period T2 of 8.3 [msec] (= 1/60 [Hz] / 2). Then, the liquid crystal display unit 30 displays each frame image after the frame rate conversion, and the backlight 40 emits light in synchronization with the display.

  First, in the period of timing t20 to t21, the liquid crystal display unit 30 performs line sequential scanning from the uppermost part to the lowermost part to display the frame image F (n) (FIG. 9A). Then, the light emitting portions BL1 to BL8 of the backlight 40 are turned off in synchronization with the line sequential scanning (FIG. 9B).

  Similarly, the liquid crystal display unit 30 performs line-sequential scanning in the period of timings t21 to t22, and displays the frame image F (n) again (FIG. 9A). That is, in this example, the display of the frame image F (n) is performed twice during the period from the timing t20 to t22. Then, the light emitting portions BL1 to BL8 of the backlight 40 are turned on in synchronization with the second line sequential scanning (FIG. 9B).

  Thereafter, the liquid crystal display unit 30 similarly starts displaying the next frame image F (n + 1) by line sequential scanning after timing t22 (FIG. 9A), and each light emission of the backlight 40 is performed. The portions BL1 to BL8 are turned off in synchronization with the first line sequential scanning (FIG. 9B).

  FIG. 10 shows a timing chart of the display operation in the delay time priority mode M2, in which (A) shows the operation of the liquid crystal display unit 30, and (B) shows the operation of the backlight 40.

  First, in the period from timing t30 to t31, the liquid crystal display unit 30 performs line sequential scanning from the uppermost part to the lowermost part to display the frame image F (n) (FIG. 10A). The light emitting portions BL1 to BL8 of the backlight 40 are turned on in synchronization with the line sequential scanning, and are turned off after the lighting time ton (FIG. 10B).

  Then, the liquid crystal display unit 30 performs line-sequential scanning in the period of timings t31 to t32, and displays the frame image F (n) again (FIG. 6A).

  Thereafter, the liquid crystal display unit 30 similarly starts displaying the next frame image F (n + 1) by line-sequential scanning after the timing t32 (FIG. 6A).

  As described above, even in the case of this modification, the display delay time can be shortened as in the case of the above-described embodiment.

[Modification 1-3]
In the above embodiment, the backlight 40 has the eight light emitting portions BL1 to BL8. However, the present invention is not limited to this, and instead, for example, seven or less or nine or more light emission. You may comprise using a part.

[Modification 1-4]
In the above embodiment, the backlight 40 has a plurality of (eight in this example) light emitting portions BL1 to BL8 that can independently emit light, but the present invention is not limited to this, and instead. Thus, a backlight that emits light simultaneously on one side may be used. The details will be described below.

  FIG. 11 illustrates a configuration example of the backlight 40C according to the present modification. The backlight 40C is a so-called edge-type backlight. In this example, the backlight 40C has light emitting portions BLT and BLB above and below the drawing, respectively. These light emitting units BLT and BLB are controlled to emit light simultaneously. The light emitted from the light emitting portions BLT and BLB is guided by a light guide plate (not shown) or the like, and emits surface light from the region Z0 to the liquid crystal display portion 30.

  12A and 12B are timing charts of the display operation in the image quality priority mode M1 of the display device 1C according to this modification. FIG. 12A shows the operation of the liquid crystal display unit 30, and FIG. 12B shows the backlight 40. Shows the operation.

  First, in the period from timing t40 to t41, the liquid crystal display unit 30 performs line sequential scanning from the uppermost part to the lowermost part to display the frame image F (n) (FIG. 12A). Similarly, the liquid crystal display unit 30 performs line-sequential scanning and repeats display of the frame image F (n) in the period of timing t41 to t42, the period of timing t42 to t43, and the period of timing t43 to t44. Then, in the middle of the fourth line sequential scanning, the backlight 40C starts to emit light.

  Thereafter, the liquid crystal display unit 30 similarly starts displaying the next frame image F (n + 1) by line-sequential scanning after timing t44 (FIG. 12A). In this example, the backlight 40C is turned off when the first line-sequential scanning reaches the vicinity of the center of the display surface of the liquid crystal display unit 30 in the vertical direction.

  FIG. 13 is a timing chart of the display operation in the delay time priority mode M2 of the display device 1C. (A) shows the operation of the liquid crystal display unit 30, and (B) shows the operation of the backlight 40. .

  First, in the period from timing t50 to t51, the liquid crystal display unit 30 performs line sequential scanning from the uppermost part to the lowermost part to display the frame image F (n) (FIG. 13A). The backlight 40C starts to emit light during the line sequential scanning.

  Then, the liquid crystal display unit 30 performs line-sequential scanning in the period from timing t51 to t52, the period from timing t52 to t53, and the period from timing t53 to t54, and repeatedly displays the frame image F (n) (FIG. 13 ( A)). The backlight 40C is turned off during the second line-sequential scanning in the period from the timing t51 to t52.

  After that, the liquid crystal display unit 30 similarly starts displaying the next frame image F (n + 1) by line sequential scanning after timing t54 (FIG. 13A).

  FIG. 14 shows the light emission timing of the backlight 40C in the delay time priority mode M2 of the display device 1C in more detail, (A) shows the operation of the liquid crystal display unit 30, and (B) shows the backlight. The operation of 40C is shown.

  As shown in FIG. 14, in the backlight 40 </ b> C, the center tc <b> 0 of the light emission period is set to the first period P <b> 0 </ b> A of the display period P <b> 0 of the liquid crystal display unit 30. Here, in the display period P0, the first line sequential scanning of the frame image F (n) starts from the timing ts0 when the vertical center of the display surface of the liquid crystal display unit 30 is reached, and the next frame image F ( The first line-sequential scanning for n + 1) ends at the timing te0 when the vertical center of the display surface of the liquid crystal display unit 30 is reached.

  As described above, in the display device 1C, in the delay time priority mode M2, the center tc0 of the light emission period of the backlight 40C is set within the first half period P0A of the display period P0. Similarly, the display delay time can be shortened.

<2. Second Embodiment>
Next, a display device according to a second embodiment will be described. In the present embodiment, the backlight 40 in the first embodiment is configured to emit light at another timing. In addition, the same code | symbol is attached | subjected to the component substantially the same as the display apparatus 1 which concerns on the said 1st Embodiment, and description is abbreviate | omitted suitably.

  FIG. 15 illustrates a configuration example of the display device 2 according to the present embodiment. The display device 2 includes a video signal processing unit 51, a frame rate conversion unit 52, and a backlight driving unit 54.

  The video signal processing unit 51 performs video signal processing on the video signal Sdisp and outputs it as a video signal Sdisp1, and generates a histogram HLV related to the pixel signal level LV based on the video signal Sdisp, thereby obtaining a brightness histogram signal. It also has a function of outputting as Sh.

  FIG. 16 shows an example of the histogram HLV. In FIG. 16, the horizontal axis indicates the pixel signal level LV of each pixel, and the vertical axis indicates the number of pixels. That is, the histogram HLV represents the number of pixels to which the pixel signal level LV is supplied for each pixel signal level LV. In this example, the histogram is generated in units of pixels. However, the present invention is not limited to this. For example, the histogram may be generated in units of pixel blocks including a plurality of pixels.

  The frame rate conversion unit 52 performs frame rate conversion based on the video signal Sdisp1, outputs the conversion result as the video signal Sdisp2, outputs a synchronization signal Ssync synchronized with the video signal Sdisp2, and outputs the motion vector signal Sv. Generate and output.

  The frame rate conversion unit 52 includes a motion vector detection unit 55. The motion vector detection unit 55 detects a motion vector indicating a change in the image based on a series of frame images supplied by the video signal Sdisp1. Specifically, the motion vector detection unit 55 performs horizontal and vertical display contents in units of pixels, for example, based on image information of two temporally adjacent frame images in the supplied series of frame images. Directional motion is detected to determine a motion vector. The motion vector detection unit 55 outputs a series of motion vectors obtained for each pixel as a motion vector signal Sv. In this example, the motion vector is obtained in units of pixels. However, the present invention is not limited to this. For example, the motion vector is detected by detecting the motion of the display content in units of pixel blocks composed of a plurality of pixels. May be requested.

  The backlight drive unit 54 drives the backlight 40 based on the synchronization signal Ssync, the operation mode signal Smode, the brightness histogram signal Sh, and the motion vector signal Sv. The backlight drive unit 54 controls the backlight 40 to emit light in another period in addition to the light emission period of the backlight 40 in the first embodiment. Specifically, the backlight drive unit 54 controls to provide another light emission period (sub light emission period) between the light emission periods (main light emission periods) adjacent to each other in the first embodiment. Is. At that time, as will be described later, the backlight driving unit 54 obtains a light emission amount in each light emission period based on the brightness histogram signal Sh and the motion vector signal Sv, and drives the backlight 40 based on the light emission amount. It is like that. Specifically, as described later, the backlight drive unit 54 has a high pixel signal level LV (when the display screen is bright) or a small motion vector (when the movement of the display content is small) (hereinafter, “ For example, the light emission amount Am in the main light emission period and the light emission amount As in the sub light emission period are set to substantially the same amount. Further, as will be described later, the backlight drive unit 54 has a low pixel signal level LV (when the display screen is dark) or a large motion vector (when the display content moves greatly) (hereinafter referred to as Case C2). For example, the light emission amount Am in the main light emission period is set to be larger than the light emission amount As in the sub light emission period.

  FIG. 17 shows a timing chart of the display operation in the image quality priority mode M1, (A) shows the operation of the liquid crystal display unit 30, and (B) and (C) show the operation of the backlight 40 in the case C1. The brightness | luminance of light emission part BL1-BL8 is shown, (D), (E) shows the operation | movement of the backlight 40 in case C2, and the brightness | luminance of light emission part BL1-BL8.

  In the display device 2, in the image quality priority mode M <b> 1, the light emitting units BL <b> 1 to BL <b> 8 of the backlight 40 are the fourth line sequential as in the case of the display device 1 according to the first embodiment (FIG. 5). In synchronization with the scanning, the light is turned on with a light emission amount Am (main light emission period). The light emitting portions BL1 to BL8 of the backlight 40 are further lit at the light emission amount As (sub light emission period) in synchronization with the second line sequential scanning, unlike the display device 1. The end timing of the main light emission period and the end timing of the sub light emission period are set apart from each other by a time T0 / 2. Details will be described below.

  First, the liquid crystal display unit 30 performs line-sequential scanning from the top to the bottom based on the drive signal supplied from the display drive unit 20 during the period of timing t60 to t61, and the frame image F (n) Display is performed (FIG. 17A).

  Next, the liquid crystal display unit 30 performs the second line sequential scanning in the period of timings t61 to t62, and repeatedly displays the frame image F (n) (FIG. 17A). And each light emission part BL1-BL8 of the backlight 40 light-emits by the light emission amount As in the sub light emission period (lighting time tons) synchronized with this 2nd line sequential scanning (FIG. 17 (B)-(E)). ).

  Next, the liquid crystal display unit 30 performs the third line sequential scanning in the period of timing t62 to t63, and repeatedly displays the frame image F (n) (FIG. 17A).

  Next, the liquid crystal display unit 30 performs the fourth line-sequential scanning in the period of timing t63 to t64, and repeatedly displays the frame image F (n) (FIG. 17A). And each light emission part BL1-BL8 of the backlight 40 light-emits by light emission amount Am in the main light emission period (lighting time Tom) synchronized with this 4th line sequential scanning (FIG. 17 (B)-(E)). ).

  Thereafter, the liquid crystal display unit 30 similarly starts displaying the next frame image F (n + 1) by line-sequential scanning after timing t64 (FIG. 17A).

  As described above, in the image quality priority mode M1, the light emitting units BL1 to BL8 of the backlight 40 emit light with the light emission amount Am in the main light emission period synchronized with the fourth line sequential scanning and perform the second line sequential scanning. Even in the synchronized sub-light emission period, light is emitted with the light emission amount As. At that time, as will be described later, the backlight driving unit 54 sets the light emission amount Am to a value equal to or greater than the light emission amount As (light emission amount Am ≧ light emission amount As). As a result, the observer mainly sees the display by the fourth line-sequential scanning in which the liquid crystal has responded sufficiently, so that the image quality deterioration is reduced as in the case of the first embodiment (FIG. 5). Can do.

  In the display device 2, the light emission amounts Am and As are controlled by the lengths of the light emission times Tom and Toms. At that time, in the image quality priority mode M1, the backlight driving unit 54 sets the luminance Ion when the light emitting units BL1 to BL8 emit light to be constant and maintains the light emission times Tom and Toms while maintaining the end timing of each light emitting period. The light emission amounts Am and As are controlled by changing each of them. In this way, by controlling the light emission amounts Am and As while maintaining the end timing of each light emission period, it is possible to reduce the possibility that the observer will feel image quality deterioration.

  Next, the magnitude relationship between the light emission amount Am and the light emission amount As will be described. As shown in FIG. 17, the magnitude relationship between the light emission amount Am and the light emission amount As is controlled to be different between the case C1 and the case C2.

  In case C1, as shown in FIG. 17C, the light emission amount Am and the light emission amount As are substantially equal to each other. In this case, the light emitting units BL1 to BL8 emit light with substantially the same amount of light twice during the time T0, and therefore, compared with the case of the display device 1 according to the first embodiment (FIG. 5). Blinking at a short cycle (high frequency), and the observer observes the display image at a high frequency.

  On the other hand, in the case C2, as shown in FIG. 17E, the light emission amount Am is set to be larger than the light emission amount As. In this case, the observer mainly observes the display based on the light emission amount Am.

  In general, when the frequency of blinking of an image falls below a certain frequency (for example, about 100 [Hz]), a person feels flicker when observing the image. This flicker is easily felt when, for example, the display screen is bright or the movement of the display content is small. Therefore, in the display device 2, when the display screen is bright or the movement of the display content is small (case C1), as shown in FIG. 17C, the light emission amount Am and the light emission amount As are substantially equal. By doing so, it is possible to increase the blinking frequency and reduce the possibility that the observer feels flicker.

  On the other hand, this flicker becomes inconspicuous when the display screen is dark or when the movement of the display content is large. However, in this case, since the display content of the fourth line sequential scan related to the light emission amount Am is the same as the display content of the second line sequential scan related to the light emission amount As, the image quality is improved by so-called hold blur. May deteriorate. Therefore, in the display device 2, when the display screen is dark or when the movement of the display content is large (case C2), as shown in FIG. 17E, the light emission amount Am is larger than the light emission amount As. By setting to, the observer mainly sees the display by the fourth line-sequential scanning related to the light emission amount Am, so that it is possible to suppress deterioration in image quality due to hold blur.

  In addition, when the brightness of the display screen is medium and the movement of the display content is medium (a state intermediate between the case C1 and the case C2), the difference between the light emission amount Am and the light emission amount As is the case C1. In the case of FIG. 17C (FIG. 17C) and the case C2 (FIG. 17E), an intermediate level is set. As a result, since the blinking frequency becomes high, it becomes difficult for the observer to feel flicker, and the display by the fourth line sequential scan related to the light emission amount Am is displayed by the second line sequential scan related to the light emission amount As. Since the image is displayed more strongly, it is possible to suppress deterioration in image quality due to hold blur.

  FIG. 18 shows a timing chart of the display operation in the delay time priority mode M2, (A) shows the operation of the liquid crystal display unit 30, and (B) and (C) show the operation of the backlight 40 in the case C1. And (D) and (E) show the operation of the backlight 40 and the luminance of the light emitting parts BL1 to BL8 in the case C2.

  In the display device 2, in the delay time priority mode M2, the light emitting units BL1 to BL8 of the backlight 40 are the first line as in the case of the display device 1 according to the first embodiment (FIG. 6). Lights up with a light emission amount Am in synchronization with sequential scanning (main light emission period). The light emitting portions BL1 to BL8 of the backlight 40 are further lit at the light emission amount As (sub light emission period) in synchronization with the third line sequential scanning, unlike the display device 1. The start timing of the main light emission period and the start timing of the sub light emission period are set apart from each other by a time T0 / 2.

  First, the liquid crystal display unit 30 performs line-sequential scanning from the top to the bottom based on the drive signal supplied from the display drive unit 20 during the period of timing t70 to t71, and the frame image F (n) Display is performed (FIG. 18A). And each light emission part BL1-BL8 of the backlight 40 light-emits by light emission amount Am in the main light emission period (lighting time Tonm) synchronized with this line-sequential scanning (FIG. 18 (B)-(E)).

  Next, the liquid crystal display unit 30 performs the second line sequential scanning in the period of timings t71 to t72, and repeatedly displays the frame image F (n) (FIG. 18A).

  Next, the liquid crystal display unit 30 performs line-sequential scanning for the third time in the period from timing t72 to t73, and repeatedly displays the frame image F (n) (FIG. 18A). And each light emission part BL1-BL8 of the backlight 40 light-emits with the light emission amount As in the sub light emission period (lighting time Tons) synchronized with this 3rd line sequential scanning (FIG.18 (B)-(E)). ).

  Next, the liquid crystal display unit 30 performs the fourth line-sequential scanning in the period from timing t73 to t74, and repeatedly displays the frame image F (n) (FIG. 18A).

  Thereafter, the liquid crystal display unit 30 similarly starts displaying the next frame image F (n + 1) by line-sequential scanning after timing t74 (FIG. 18A).

  As described above, in the delay time priority mode M2, the light emitting units BL1 to BL8 of the backlight 40 emit light with the light emission amount Am in the main light emission period synchronized with the second line sequential scanning and the fourth line sequential scanning. Even in the sub-emission period synchronized with, the light emission amount As is emitted. At that time, as will be described later, the backlight driving unit 54 sets the light emission amount Am to a value equal to or greater than the light emission amount As (light emission amount Am ≧ light emission amount As). Thus, since the observer mainly sees the display by the second line sequential scanning, the video signal is actually supplied to the display device 2 as in the case of the first embodiment (FIG. 6). The time (delay time) until display is performed can be shortened.

  Further, in the delay time priority mode M2, the backlight drive unit 54 controls the light emission amounts Am and As by changing the light emission times Tom and Toms while maintaining the start timing of each light emission period. In this way, a short delay time can be maintained by controlling the light emission amounts Am and As while maintaining the start timing of the light emission period.

  The light emission amounts Am and As are set in the same manner as in the image quality priority mode M1 described above. As a result, even in the delay time priority mode M2, the display device 2 can reduce the possibility that the observer feels flicker when the display screen is bright or the movement of the display content is small (case C1). In the case where the display screen is dark or the movement of the display content is large (case C2), it is possible to suppress a decrease in image quality due to hold blur. In addition, when the brightness of the display screen is medium and the movement of the display content is medium (a state intermediate between the case C1 and the case C2), the observer is less likely to feel flicker and the image quality due to hold blur is high. Can be suppressed.

  The backlight drive unit 54 obtains the light emission amount Am in the main light emission period and the light emission amount As in the sub light emission period based on the brightness histogram signal Sh and the motion vector signal Sv. Hereinafter, the operation of the backlight drive unit 54 will be described.

  FIG. 19 shows a flowchart of the operation in the backlight drive unit 54. The backlight drive unit 54 first performs the motion vector processing flow Fv and the brightness histogram processing flow Fh in parallel, and obtains the light emission amounts Am and As based on the processing results. The details will be described below.

  First, the motion vector processing flow Fv will be described.

  First, the backlight drive unit 54 performs scroll determination in the motion vector processing flow Fv (step S11). Specifically, the backlight drive unit 54 determines that, based on the motion vector signal Sv, the screen is scrolling when the motion vector of each pixel is substantially the same size and faces the same direction. judge. If it is determined that scrolling has been performed, the process proceeds to step S15. If it is determined that scrolling has not been performed, the process proceeds to step S12.

  If it is determined in step S11 that the image is not scrolled, then the backlight drive unit 54 integrates the magnitude of the motion vector of each pixel over the entire screen based on the motion vector signal Sv. An amount N is obtained (step S12). That is, the motion amount N increases as the motion of the display content in a series of frame images increases.

  Next, the backlight drive unit 54 checks whether or not the motion amount N obtained in step S12 is greater than a predetermined threshold value Vth (step S13). That is, in this flow, it is determined whether or not the display content of the frame image has moved by a predetermined amount or more. If the amount of movement N is greater than the predetermined threshold value Vth, the process proceeds to step S15, and if the amount of movement N is less than or equal to the predetermined threshold value Vth, the process proceeds to step S14.

  If it is determined in step S13 that the amount of motion N is equal to or less than the predetermined threshold value Vth, then the backlight drive unit 54 substitutes the amount of motion N into the predetermined function fv to obtain a variable. Av is obtained (step S14). The function fv (N) is a function that outputs a larger value as the motion amount N is smaller. The variable Av has a value of 0 or more. As will be described later, the light emission amount As in the sub light emission period is set to be larger as the value of the variable Av is larger. Thereafter, the flow proceeds to step S31.

  If it is determined in step S11 that scrolling is being performed, or if it is determined in step S13 that the amount of motion N is greater than the predetermined threshold value Vth, the backlight drive unit 54 sets the variable Av to 0. (Step S15). Thereafter, the flow proceeds to step S31.

  Next, the brightness histogram processing flow Fh will be described.

  First, in the brightness histogram processing flow Fh, the backlight driving unit 54 obtains the ratio Y in the total number of pixels of the number of pixels whose pixel signal level LV is higher than a predetermined threshold LVth based on the brightness histogram signal Sh. (Step S21). Specifically, the backlight drive unit 54 obtains the number of pixels in the portion (hatched portion) where the pixel signal level LV is larger than the threshold value LVth in the histogram HLV (FIG. 16), and calculates the number of pixels as a whole pixel. The ratio Y is obtained by dividing by a number.

  Next, the backlight drive unit 54 obtains the variable Ah by substituting the ratio Y into a predetermined function fh (step S22). The function fh (Y) is a function that outputs a larger value as the ratio Y is larger. The variable Ah has a value of 0 or more. As will be described later, the light emission amount Ah in the sub light emission period is set to a larger value as the value of the variable Ah is larger. Thereafter, the flow proceeds to step S31.

  Thereafter, based on the variable Av obtained by the motion vector processing flow Fv and the variable Ah obtained by the brightness histogram processing flow Fh, the light emission amounts Am and As are obtained as follows.

  First, the backlight drive unit 54 obtains the light emission amount As in the sub light emission period by adding the variable Av obtained in step S14 or step S15 and the variable Ah obtained in step S22 (step S31).

  Next, the backlight drive unit 54 checks whether or not the result (As / Atotal) obtained by dividing the light emission amount As obtained in the previous step by the preset total light emission amount Atotal is greater than 1/2 ( Step S32). The total light emission amount Atotal is set by the user as a parameter for the brightness of the display screen via the user interface (UI), for example. If As / Atotal is greater than 1/2, the process proceeds to step S33, and if As / Atotal is 1/2 or less, the process proceeds to step S34.

  If As / Atotal is larger than ½ in step S32, then the backlight driving unit 54 sets the light emission amount As to a value half of the total light emission amount Atotal (Atotal / 2) (step S32). S33).

  Next, the backlight drive unit 54 obtains the light emission amount Am in the main light emission period by subtracting the light emission amount As from the total light emission amount Atotal (step S34).

  Thus, this flow ends.

  Thus, in the display device 2, the variables Av and Ah are obtained by the motion vector processing flow Fv and the brightness histogram processing flow Fh, the light emission amount As in the sub light emission period is obtained based on the variables Ah and Av, and the light emission amount. Based on As, the light emission amount Am is determined so that the total light emission amount Atotal is constant.

  The variable Av obtained by the motion vector processing flow Fv becomes smaller as the movement of the display content in the series of frame images increases. Specifically, for example, when it is determined that the display screen is scrolling (step S11) or when the amount of movement N is greater than a predetermined threshold value Vth (step S13), the backlight drive unit 54 is Therefore, it is determined that the movement of the display content is large, and the variable Av is set to 0. On the other hand, when the motion amount N is equal to or less than the predetermined threshold value Vth (step S13), the backlight driving unit 54 sets the variable Av to a positive value in step S14. Since the light emission amount As in the sub light emission period is obtained by adding the variable Av and the variable Ah (step S31), the light emission amount As in the sub light emission period decreases as the variable Av decreases. As described above, the backlight drive unit 54 sets the light emission amount As in the sub light emission period to a smaller value as the movement of the display content in the series of frame images is larger, and the movement in the sub light emission period as the movement of the display content is smaller. The light emission amount As is increased to almost the same level as the light emission amount Am. Thereby, in the display device 2, as described above, when the movement of the display content is large, it is possible to suppress the deterioration of the image quality due to the hold blur, and when the movement of the display content is small, the observer can flicker. The risk of feeling can be reduced.

  Further, the variable Ah obtained from the brightness histogram processing flow Fh becomes a larger value as the display screen becomes brighter. Since the light emission amount As in the sub light emission period is obtained by adding the variable Av and the variable Ah (step S31), the light emission amount As in the sub light emission period increases as the variable Ah increases. As described above, the backlight drive unit 54 sets the light emission amount As in the sub light emission period to a smaller value as the display screen becomes darker, and the light emission amount As in the sub light emission period as the light emission amount Am as the display screen becomes brighter. Increase to almost the same level. Thereby, in the display device 2, as described above, when the display screen is dark, it is possible to suppress a decrease in image quality due to hold blur, and when the display screen is bright, the possibility that the observer feels flicker is reduced. can do.

  Further, when setting the light emission amount As in the sub light emission period, the backlight drive unit 54 sets the light emission amount As so that it does not exceed half of the total light emission amount Atotal as shown in steps S32 and S33. In other words, the backlight drive unit 54 sets the light emission amounts Am and As so that the light emission amount Am is equal to or greater than the light emission amount As (light emission amount Am ≧ light emission amount As). Thereby, for example, in the image quality priority mode M1, as shown in FIG. 17, the observer performs the display by the fourth line sequential scanning related to the light emission amount Am by the second line sequential scanning related to the light emission amount As. Compared to the display, the observation is equivalent or stronger. That is, the observer strongly observes the image after the liquid crystal in the liquid crystal display unit 30 sufficiently responds, and does not strongly observe the transient display of the liquid crystal display unit 30, thereby reducing image quality degradation. be able to. Further, for example, in the delay time priority mode M2, as shown in FIG. 18, the observer performs the display by the first line sequential scanning related to the light emission amount Am by the third line sequential scanning related to the light emission amount As. Compared to the display, the observation is equivalent or stronger. That is, since the observer strongly observes the display by the first line sequential scanning performed at an early timing, the time (delay time) from when the video signal is supplied to the display device 2 until the actual display is performed is determined. Can be shortened.

  In the display device 2, the backlight drive unit 54 obtains the light emission amounts Am and As so that the sum of the light emission amount Am and the light emission amount As is constant as shown in step S34. Thereby, since the sum of the light emission amount in the main light emission period and the light emission amount in the sub light emission period is made constant, the brightness of the display screen can be made almost constant regardless of the operation mode.

  Next, an operation when the backlight drive unit 54 changes the light emission amounts Am and As of the backlight 40 will be described.

  For example, when the information of the histogram signal Sh and the motion vector signal Sv changes and the light emission amounts Am and As change, the backlight drive unit 54 drives and controls the backlight 40 based on the changed light emission amounts Am and As. At that time, the backlight drive unit 54 controls the backlight 40 so that the light emission amounts Am and As gradually change.

  FIG. 20 shows changes in the light emission amounts Am, As, where (A) shows the luminance I of the light emitting part BL1, and (B) shows the light emission quantities Am, As of the light emitting part BL1. In this example, the light emitting unit BL1 among the light emitting units BL1 to BL8 is shown as an example, but the same applies to the other light emitting units BL2 to BL8.

  This example shows a case where the light emission amount Am changes from the state where the light emission amount Am is larger than the light emission amount As (for example, the case C2) to the state where the light emission amount Am and the light emission amount As are equal to each other (for example, the case C1). When the backlight drive unit 54 determines that the light emission amount Am and the light emission amount As should be equal to each other based on the histogram signal Sh and the motion vector signal Sv at the timing t100, the backlight drive unit 54 The backlight 40 is driven so that Am and the light emission amount As gradually change. That is, the backlight drive unit 54 performs control so that the light emission amounts Am and As do not change suddenly. The time (time constant) until the light emission amounts Am and As reach final values can be set to about 1 second, for example. Thereby, for example, even if the display image changes, the light emission amounts Am and As do not change abruptly, so that the possibility that the observer feels the display image unnatural can be reduced.

  Further, the time constant is not limited to a fixed value, and may be changed according to the situation. Specifically, for example, in the scroll determination shown in step S11 of FIG. 19, when it is determined that the screen is scrolling, an instantaneous response may be made by setting this time constant short. . Further, for example, when the brightness histogram HLV changes in the direction of the higher pixel signal level LV in a short time and the brightness rapidly increases, an instantaneous response is made by setting this time constant short. Good.

  In the display device 2, the backlight drive unit 54 is driven so that the sum of the light emission amount Am and the light emission amount As is constant, so that the light emission amounts Am and As are as shown in FIG. Even in the case of a change, it is possible to reduce the possibility that the observer feels the display image unnaturally.

[effect]
As described above, in this embodiment, since both the main light emission period and the sub light emission period are provided, flicker can be reduced.

  In the present embodiment, since the light emission amount in the main light emission period and the light emission amount in the sub light emission period are changed, it is possible to suppress a decrease in image quality due to hold blur and to reduce flicker.

  In the present embodiment, since the light emission amount is controlled while maintaining the end timing of each light emission period in the image quality priority mode, it is possible to suppress deterioration in image quality.

  In the present embodiment, since the light emission amount is controlled while maintaining the start timing of each light emission period in the delay time priority mode, a short delay time can be maintained.

  In this embodiment, since the sum of the light emission amount in the main light emission period and the light emission amount in the sub light emission period is made constant, the brightness of the display screen can be made almost constant regardless of the operation mode.

  In this embodiment, since the light emission amount in the main light emission period and the light emission amount in the sub light emission period are gradually changed, it is possible to reduce the possibility that the observer feels the display image unnaturally.

  Other effects are the same as in the case of the first embodiment.

[Modification 2-1]
Any one or two or more of the modifications 1-1 to 1-4 of the first embodiment may be applied to the above embodiment.

[Modification 2-2]
In the above embodiment, the motion vector processing flow Fv and the brightness histogram processing flow Fh are executed in parallel in the operation flow of the backlight driving unit 54, but the present invention is not limited to this, and instead of this, For example, the brightness histogram processing flow Fh may be executed after the motion vector processing flow Fv, or the motion vector processing flow may be executed after the brightness histogram processing flow Fh.

[Modification 2-3]
In the above embodiment, the light emission amounts Am and As are controlled by the light emission times Tom and Toms. However, the present invention is not limited to this. For example, as shown in FIG. The light emission amounts Am and As may be controlled by Is. Further, the light emission amounts Am and As may be controlled by both the light emission times Tom and Toms and the light emission luminances Im and Is.

  The present technology has been described above with some embodiments and modifications. However, the present technology is not limited to these embodiments and the like, and various modifications are possible.

  In addition, this technique can be set as the following structures.

(1) a frame rate conversion unit;
A liquid crystal display for displaying the frame rate converted video;
A backlight that emits light intermittently;
And a backlight control unit having a plurality of operation modes having different light emission timings of the backlight.

(2) The frame rate conversion unit performs frame rate conversion by generating a plurality of subframe images that are the same as the frame image in one operation mode,
In the one operation mode, the backlight control unit sets the center of one light emission period of the backlight before the center of the display period in which the liquid crystal display unit displays the plurality of subframe images. The display device according to (1).

(3) The center of the one light emission period is in a head display period in which the liquid crystal display unit displays a head subframe image of the plurality of subframe images in the display period. The display device described.

(4) In the one operation mode, the backlight control unit also sets a sub light emission period different from the one light emission period, which emits light with a sub light emission amount equal to or less than the main light emission amount in the one light emission period. The display device according to (2) or (3).

(5) The display device according to (4), wherein the start timing of the sub light emission period is shifted from the start timing of the one light emission period by half of the display period in the one operation mode.

(6) a motion vector detection unit that detects a motion vector in a series of frame images;
The display device according to (4) or (5), wherein the backlight control unit controls the main light emission amount and the sub light emission amount based on the motion vector, respectively.

(7) The display device according to any one of (4) to (6), wherein the backlight control unit controls the main light emission amount and the sub light emission amount based on luminance information of the frame image.

(8) In the one operation mode, the backlight control unit controls to maintain the start timing of the one light emission period and the start timing of the sub light emission period, respectively (6) or (7) The display device described.

(9) The backlight control unit performs control so as to gradually change the main light emission amount and the sub light emission amount over a plurality of the display periods, according to any one of (6) to (8). Display device.

(10) The display device according to any one of (6) to (9), wherein the backlight control unit controls a sum of the main light emission amount and the sub light emission amount to be constant.

(11) The backlight control unit controls the main light emission amount and the sub light emission amount according to the length of the light emission period and the length of the sub light emission period, respectively. The display device described.

(12) The display device according to any one of (6) to (11), wherein the backlight control unit controls the main light emission amount and the sub light emission amount based on light emission luminance of the backlight.

(13) The frame rate conversion unit performs frame rate conversion by generating a plurality of subframe images that are the same as the frame image in another operation mode different from the one operation mode,
The backlight control unit sets the center of the other light emission period of the backlight after the center of the display period in which the liquid crystal display unit displays the plurality of subframe images in the other operation mode. The display device according to any one of (2) to (12).

(14) In the other operation mode, the backlight control unit emits light with another sub light emission amount equal to or less than another main light emission amount in the other light emission period. The display device according to (13), wherein a light emission period is also set, and control is performed to maintain an end timing of the other light emission period and an end timing of the other sub light emission period.

(15) The liquid crystal display unit performs display by line sequential scanning,
The backlight has a plurality of sub-light emitting units divided in the line-sequential scanning direction,
The backlight control unit sets the center of the one light emission period for each of the sub light emitting units,
The display period is a timing at which the scanning related to the first sub-frame image generated from the frame image reaches the center position which is the center in the line-sequential scanning direction in the display area corresponding to each sub-light emitting unit of the liquid crystal display unit The display device according to any one of (2) to (14), wherein scanning is started at each of the first subframe images generated from the next frame image and ends at a timing when the center position is reached. .

(16) The liquid crystal display unit performs display by line sequential scanning,
The display period is generated from the next frame image, starting from the timing when the scanning related to the first sub-frame image generated from the frame image reaches the center position which is the center in the line-sequential scanning direction in the liquid crystal display unit. The display device according to any one of (2) to (14), wherein the scanning related to the first sub-frame image is completed at a timing when the center position is reached.

(17) a frame rate conversion unit that performs frame rate conversion by generating a plurality of subframe images that are the same as the frame image;
A liquid crystal display for displaying the frame rate converted video;
A backlight that emits light intermittently;
In one operation mode, the backlight is controlled such that the center of one light emission period of the backlight comes before the center of the display period in which the liquid crystal display unit displays the plurality of subframe images. A display device comprising a backlight control unit.

(18) The display device according to (17), wherein the center of the one light emission period is in a head display period in which the liquid crystal display unit displays a head subframe image among the plurality of subframe images. .

(19) A display method in which a backlight capable of changing a light emission timing emits light intermittently and a frame rate converted image is displayed on a liquid crystal display unit.

  DESCRIPTION OF SYMBOLS 1,2 ... Display apparatus 11,51 ... Video signal processing part, 12,52 ... Frame rate conversion part, 13 ... Mode setting part, 14,54 ... Backlight drive part, 20 ... Display drive part, 21 ... Timing control Part, 22 ... gate driver, 23 ... data driver, 30 ... liquid crystal display part, 40, 40C ... backlight, 42 ... LED, 55 ... motion vector detection part 55, Ah, Av ... variable, Am, As ... emission amount, Atotal: Total light emission amount, BLB, BLT, BL1 to BL8: Light emitting unit, Cs: Retention capacitance element, CSL: Retention capacitance line, C1, C2 ... Case, GCL: Gate line, Fh ... Brightness histogram processing flow, Fv ... Motion vector processing flow, Ion, Im, Is ... Luminance, LC ... Liquid crystal element, LV ... Pixel signal level, LVth ... Threshold value, N ... Motion amount, Pix ... Pixel, P1-P8 ... Display P1A to P8A ... period, Sdisp, Sdisp1, Sdisp2, Sdisp3 ... video signal, SGL ... data line, Sh ... brightness histogram signal, Smode ... operation mode signal, Sv ... motion vector signal, Ssync ... synchronization signal, td1, td2 ... time, ton, tom, tons ... light emission time, Tr ... TFT element, T0, T1 ... period (time), Vth ... threshold value, Y ... ratio, Z1 to Z8 ... region.

Claims (19)

A frame rate conversion unit;
A liquid crystal display for displaying the frame rate converted video;
A backlight that emits light intermittently;
And a backlight control unit having a plurality of operation modes having different light emission timings of the backlight. The frame rate conversion unit performs frame rate conversion by generating a plurality of subframe images that are the same as a frame image in one operation mode,
In the one operation mode, the backlight control unit sets the center of one light emission period of the backlight before the center of the display period in which the liquid crystal display unit displays the plurality of subframe images. The display device according to claim 1. 3. The display device according to claim 2, wherein the center of the one light emission period is in a head display period in which the liquid crystal display unit displays a head subframe image of the plurality of subframe images in the display period. . The backlight control unit also sets a sub light emission period that is different from the one light emission period and emits light with a sub light emission amount equal to or less than a main light emission amount in the one light emission period in the one operation mode. The display device described in 1. The display device according to claim 4, wherein the start timing of the sub light emission period is shifted from the start timing of the one light emission period by a half of the display period in the one operation mode. A motion vector detection unit for detecting a motion vector in a series of frame images;
The display device according to claim 4, wherein the backlight control unit controls the main light emission amount and the sub light emission amount based on the motion vector. The display device according to claim 4, wherein the backlight control unit controls the main light emission amount and the sub light emission amount based on luminance information of the frame image. The display device according to claim 6, wherein the backlight control unit performs control so as to maintain a start timing of the one light emission period and a start timing of the sub light emission period, respectively, in the one operation mode. The display device according to claim 6, wherein the backlight control unit performs control so as to gradually change the main light emission amount and the sub light emission amount over a plurality of the display periods. The display device according to claim 6, wherein the backlight control unit controls the sum of the main light emission amount and the sub light emission amount to be constant. The display device according to claim 6, wherein the backlight control unit controls the main light emission amount and the sub light emission amount according to a length of the light emission period and a length of the sub light emission period, respectively. The display device according to claim 6, wherein the backlight control unit controls the main light emission amount and the sub light emission amount based on light emission luminance of the backlight. The frame rate conversion unit performs frame rate conversion by generating a plurality of subframe images that are the same as a frame image in another operation mode different from the one operation mode,
The backlight control unit sets a center of another light emission period of the backlight after the center of a display period in which the liquid crystal display unit displays the plurality of subframe images in the other operation mode. Item 3. The display device according to Item 2. In the other operation mode, the backlight control unit emits light with another sub light emission amount that is equal to or less than another main light emission amount in the other light emission period, and has another sub light emission period different from the other light emission period. The display device according to claim 13, wherein control is also performed so that the end timing of the other light emission period and the end timing of the other sub light emission period are respectively maintained. The liquid crystal display unit performs display by line sequential scanning,
The backlight has a plurality of sub-light emitting units divided in the line-sequential scanning direction,
The backlight control unit sets the center of the one light emission period for each of the sub light emitting units,
The display period is a timing at which the scanning related to the first sub-frame image generated from the frame image reaches the center position which is the center in the line-sequential scanning direction in the display area corresponding to each sub-light emitting unit of the liquid crystal display unit The display device according to claim 2, wherein scanning is started at each of the first sub-frame images generated from the next frame image and ends at a timing when the center position is reached. The liquid crystal display unit performs display by line sequential scanning,
The display period is generated from the next frame image, starting from the timing when the scanning related to the first sub-frame image generated from the frame image reaches the center position which is the center in the line-sequential scanning direction in the liquid crystal display unit. The display device according to claim 2, wherein the scanning related to the first sub-frame image is completed at a timing when the center position is reached. A frame rate conversion unit that performs frame rate conversion by generating a plurality of subframe images that are the same as the frame image;
A liquid crystal display for displaying the frame rate converted video;
A backlight that emits light intermittently;
In one operation mode, the backlight is controlled such that the center of one light emission period of the backlight comes before the center of the display period in which the liquid crystal display unit displays the plurality of subframe images. A display device comprising a backlight control unit. The display device according to claim 17, wherein the center of the one light emission period is in a head display period in which the liquid crystal display unit displays a head subframe image of the plurality of subframe images. A display method in which a backlight capable of changing the light emission timing emits light intermittently and a frame rate converted image is displayed on a liquid crystal display unit.

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