WO2012002411A1 - Liquid crystal display device - Google Patents

Liquid crystal display device Download PDF

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Publication number
WO2012002411A1
WO2012002411A1 PCT/JP2011/064864 JP2011064864W WO2012002411A1 WO 2012002411 A1 WO2012002411 A1 WO 2012002411A1 JP 2011064864 W JP2011064864 W JP 2011064864W WO 2012002411 A1 WO2012002411 A1 WO 2012002411A1
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WO
WIPO (PCT)
Prior art keywords
liquid crystal
crystal display
image
response time
light source
Prior art date
Application number
PCT/JP2011/064864
Other languages
French (fr)
Japanese (ja)
Inventor
大木　謙太郎
基行 鬼木
岩崎　弘治
Original Assignee
シャープ株式会社
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Publication of WO2012002411A1 publication Critical patent/WO2012002411A1/en

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G09G3/342—Control of illumination source using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/024—Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/08—Details of timing specific for flat panels, other than clock recovery

Definitions

  • the present invention relates to a liquid crystal display device that controls the alignment state of liquid crystals and the lighting time of a light source.
  • Liquid crystal display devices that occupy a small indoor area compared to the size of the display screen are widely used because they can effectively use a limited indoor space.
  • the liquid crystal display device irradiates light from a light source unit accommodated in a rear cabinet to a liquid crystal display panel that displays an image arranged inside the front cabinet, and is based on input image information (image frame). It is configured to display an image.
  • the liquid crystal display panel sequentially displays images based on sequentially input image frames.
  • the gradation change in the same pixel between one image and another image displayed next to the one image is Different for each pixel. Therefore, the response time of each part of the liquid crystal display panel corresponding to each part of the image also increases or decreases according to the change in gradation in each part of the image.
  • fixed values indicating the light extinction start time and the light extinction time of the light source unit are set in advance, and the difference in response time in each part of the image is not considered.
  • the present invention has been made in view of such circumstances, and even when the response time of the liquid crystal display panel varies from part to part, a liquid crystal display device capable of preventing the generation of pseudo contours and improving the display quality is provided.
  • the purpose is to provide.
  • the liquid crystal display device includes a liquid crystal display panel that displays sequentially input images, and a plurality of light sources that are arranged in parallel to face the liquid crystal display panel and emit light toward the liquid crystal display panel.
  • the plurality of light sources are intermittently lit during a display period in which the input image is displayed on the liquid crystal display panel, each of the portions of the liquid crystal display panel facing each light source Based on the gradation change of the first partial image in the displayed one image and the second partial image in the next sequential image, the response time calculating means for calculating the response time and the response time calculating means And a light extinction period setting means for setting a light extinction period of the light source in the display period based on the response time.
  • the response time of the liquid crystal display panel corresponding to the change in gradation between one image displayed sequentially and the other image is calculated and calculated. Based on the response time, an extinguishing period of the light source is set, and the light source is extinguished while the arrangement state of the liquid crystal elements is changed in the portion of the liquid crystal display panel.
  • the liquid crystal display device is characterized in that the response time calculation means calculates a change in gradation between the two partial images.
  • the gradation change of the first partial image and the second partial image is obtained, and the response time of the liquid crystal display panel at the position corresponding to the first partial image and the second partial image is obtained based on the obtained gradation change. Is calculated.
  • the response time calculation unit corresponds to each of a plurality of image areas constituting the first partial image and a plurality of image areas constituting the first partial image
  • the gradation change of the first partial image and the second partial image displayed in each part of the liquid crystal display panel is obtained for each corresponding image area, and based on the obtained maximum gradation change, The light source extinction period is set, and the light source is extinguished until the response of the liquid crystal element is finished in each part of the liquid crystal display panel.
  • the liquid crystal display device includes current value control means for controlling the drive current of the light source facing the facing portion based on the response time calculated by the response time calculation means. .
  • the driving current of the light source is controlled in correspondence with the extinguishing period set based on the response time, and the uniformization of the luminance in the entire liquid crystal display panel is promoted.
  • the liquid crystal display device is characterized in that the current value control means increases or decreases the drive current according to the length of the extinction period set by the extinction period setting means.
  • the drive current at the time of lighting is increased to increase the luminance of the light source, and when the set extinction period is short, at the time of lighting
  • the drive current is reduced to reduce the luminance of the light source, and the luminance during the period in which the image is held on the liquid crystal display panel (display period) is made uniform.
  • the response time corresponding to the gradation change between the sequentially displayed one image and the next image is calculated.
  • the light source is turned off, and the light source is turned off while the arrangement state of the liquid crystal elements is changing in each part of the liquid crystal display panel. Even when the response time varies from part to part, it is possible to prevent the occurrence of pseudo contours and improve the display quality.
  • FIG. 3 is a block diagram schematically showing a light source driving circuit. It is a timing chart which shows the relationship between a vertical synchronizing signal and an LED driver.
  • FIG. 1 is a perspective view showing an appearance of a liquid crystal display device
  • FIG. 2 is a front view schematically showing a light source unit.
  • reference numeral 1 denotes a rectangular liquid crystal display panel having liquid crystal and TFT (Thin Film Transistor).
  • the liquid crystal display panel 1 controls the voltage applied to the liquid crystal by controlling the operation of the TFT, and changes the alignment state of the liquid crystal elements to adjust the light transmittance. By adjusting the light transmittance, a predetermined image is displayed on the front surface of the liquid crystal display panel 1.
  • the liquid crystal display panel 1 has a peripheral edge sandwiched between a front holding frame and a rear holding frame (both not shown), and is housed in a rectangular frame-shaped front cabinet 2.
  • the front cabinet 2 is disposed around the front holding frame and the rear holding frame.
  • the front cabinet 2 has a rectangular opening, and the dimension of the opening corresponds to the liquid crystal display panel 1.
  • a rectangular plate-like backlight chassis 4 is disposed on the rear side of the liquid crystal display panel 1.
  • a plurality (eight in this embodiment) of light source units 5a to 5h are supported at the front portion of the backlight chassis 4.
  • the light source units 5 a to 5 h and the backlight chassis 4 are accommodated in the rear cabinet 3.
  • the front edge of the rear cabinet 3 is provided with an engaging convex part (not shown), and the rear edge part of the front cabinet 2 is provided with an engaging concave part (not shown).
  • the engaging concave part and the engaging convex part are engaged with each other.
  • the front cabinet 2 and the rear cabinet 3 are connected.
  • the light source units 5a to 5h are lined up and down, with the light source unit 5a positioned at the top and the light source unit 5h positioned at the bottom.
  • the light source units 5a to 5h include a rectangular horizontally long substrate 50 and a plurality of LEDs (Light Emitting Diodes) 51, 51,... 51 mounted on the substrate 50.
  • the LEDs 51, 51,..., 51 are arranged in the horizontal direction at equal intervals on the substrate 50, and are connected in series.
  • Each part of the liquid crystal display panel 1 facing the light source units 5a to 5h is shown as a first part 1a to an eighth part 1h in FIG.
  • FIG. 3 is a block diagram schematically showing the configuration in the vicinity of the backlight control unit 70 and the video processing unit 10.
  • An image frame is input to the liquid crystal display panel 1 through a video processing unit 10, a double speed processing unit 20, an OS (Over Shoot) processing unit 30, a video analysis processing unit 40, and a liquid crystal display panel timing generation unit 50.
  • An image frame indicating an image is input to the video processing unit 10 from a terminal (not shown) such as a tuner and HDMI (High Definition Multimedia Interface).
  • the video processing unit 10 performs contrast correction, color correction processing, and the like on the input image frame, and outputs the result to the double speed processing unit 20.
  • the double speed processing unit 20 executes a process of doubling the number of images transmitted within a predetermined time based on the input image frame, and outputs the image frame to the OS processing unit 30.
  • the OS processing unit 30 performs processing for generating and adding overshoot or undershoot to the signal related to the input image frame, and outputs the image frame to the video analysis processing unit 40.
  • the video analysis processing unit 40 changes the gradation between one image and another image displayed on the liquid crystal display panel 1 next to the one image.
  • a response time based on the light source units 5a to 5h is calculated, and based on the calculated response time, the light source units 5a to 5a in a period (display period) in which one image is held in the liquid crystal display panel 1 are calculated.
  • 5h to determine the turn-off start time and turn-off time of each light source unit 5a to 5h, obtain the drive current magnitude of each of the light source units 5a to 5h, and backlight control information indicating the obtained turn-off start time, turn-off time and drive current magnitude To the unit 70.
  • the gradation change is a numerical value that depends on each gradation value before and after the change, and corresponds to the transition time of the liquid crystal element, and the difference between the gradation value before the change and the gradation value after the change. Does not mean (absolute value).
  • the transition time of the liquid crystal element when the gradation changes from the gradation value 128 to the gradation value 0 and the transition time of the liquid crystal element when the gradation value changes from the gradation value 228 to the gradation value 100 If they are different, the absolute value in the former is equal to the absolute value in the latter, but the gradation change in the former and the gradation change in the latter are different.
  • each gradation value before and after the change can be calculated by multiplying each gradation value by a predetermined correction coefficient, and the gradation change can be obtained based on each calculated value.
  • each gradation value before and after the change may be calculated by applying it to a predetermined function, and the gradation change may be obtained based on each calculated value. In either case, the difference between the calculated values or the division result can be obtained as a gradation change.
  • the backlight control unit 70 includes an MPU (Micro Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) (not shown), and further includes a light source driving circuit 71 that drives the light source units 5a to 5h.
  • the MPU of the backlight control unit 70 controls the operation of the light source drive circuit 71 based on the input information indicating the start time of turn-off, the turn-off time, and the magnitude of the drive current, and controls the drive of the light source units 5a to 5h. To do.
  • the video analysis processing unit 40 outputs the image frame to the liquid crystal display panel timing generation unit 50.
  • the liquid crystal display panel timing generation unit 50 includes a clock (not shown), and outputs a vertical synchronization signal VS and a horizontal synchronization signal HS to the liquid crystal display panel timing generation unit 50 based on the clocking result of the clock.
  • the liquid crystal display panel timing generation unit 50 outputs an image frame to the liquid crystal display panel 1.
  • the vertical synchronization signal VS and the horizontal synchronization signal HS are pulse waves, and the period of the pulse wave of the vertical synchronization signal VS is equal to the period in which the image frame is output from the liquid crystal display panel timing generation unit 50.
  • the liquid crystal display panel 1 displays an image based on the image frame input from the liquid crystal display panel timing generation unit 50, and after the pulse wave of the vertical synchronization signal VS is input until the next pulse wave is input. , Keep the same image.
  • FIG. 4 is a block diagram schematically showing the configuration of the video analysis processing unit 40
  • FIG. 5 is a conceptual diagram showing one configuration example of the ROM
  • FIG. 6 is a conceptual diagram showing another configuration example of the ROM.
  • the video analysis processing unit 40 includes an MPU 41, a ROM 42 that stores a control program, a RAM 43 that temporarily stores information, an input I / F (InterFace) 44, and an output I / F 45 that are mutually connected via a common bus. ing.
  • the MPU 41 reads the control program stored in the ROM 42 into the RAM 43 and executes it.
  • the image analysis processor 40 receives an image frame from the OS processor 30 via the input I / F 44. Further, an image frame is output to the liquid crystal display panel timing generation unit 50 via the output I / F 45, and information indicating the turn-off start time and turn-off time of each of the light source units 5a to 5h and the light source unit 5a are output to the backlight control unit 70. Information indicating the magnitude of each of the drive currents for up to 5 hours is output.
  • the ROM 42 includes a look-up table (LUT) 42a indicating the relationship between a gradation change described later and a response time corresponding to the gradation change, a turn-off start time, a turn-off time, and the magnitude of the drive current.
  • LUT look-up table
  • storage areas 420, 421,... are set for each image frame sequentially input from the OS processing unit 30.
  • the storage areas 420, 421,... include segments corresponding to the first part 1a to the eighth part 1h described above.
  • the MPU 41 divides the image frame and stores it in each segment of the storage area. Then, the MPU 41 obtains a gradation change between sequentially input image frames for each segment, calculates a response time based on the obtained gradation change, and calculates the turn-off start time, the turn-off time, and the magnitude of the drive current. Information is generated and output to the backlight control unit 70.
  • the MPU 41 divides information indicating one image related to the input image frame so as to correspond to the first part 1a to the eighth part 1h, and stores the divided information in the segments 420a to 420h of the storage area 420. .
  • an image frame indicating another image displayed on the liquid crystal display panel 1 next to one image is divided corresponding to each of the first part 1a to the eighth part 1h, and the divided image frame is divided into each of the storage areas 421. Store in segments 421a-421h.
  • the MPU 41 Based on the image frames stored in the segments 420a to 420h, the MPU 41 performs gradation of partial images (first partial images) constituting one image displayed in each of the first part 1a to the eighth part 1h. Are calculated for each of the first part 1a to the eighth part 1h. Further, based on the image frames stored in the segments 421a to 421h, the gradations of partial images (second partial images) constituting other images displayed in the first part 1a to the eighth part 1h, respectively, Calculation is performed for each of the first part 1a to the eighth part 1h. Examples of the calculated gradation include the average gradation of the pixel group constituting the first part 1a to the eighth part 1h or the gradation of the pixel located at the center of each part. Then, for each of the first part 1a to the eighth part 1h, the gradation change of the corresponding first partial image and second partial image is obtained.
  • the MPU 41 refers to the LUT 42a, determines the response time corresponding to the obtained gradation change, acquires the turn-off start time, the turn-off time, and the magnitude of the drive current from the determined response time, Information indicating the turn-off time and the magnitude of the drive current is output to the backlight control unit 70.
  • the LUT 42a stores, for example, information indicating that the turn-off start time becomes earlier as the response time becomes smaller for each of the first part 1a to the eighth part 1h, and the drive current increases as the response time becomes larger. Stores information indicating that the size increases.
  • the above processing for calculating the response time based on the gradation change and outputting information indicating the magnitude of the light extinction start time, the light extinction time, and the drive current to the backlight control unit 70 includes the light extinction start time, the extinction time, and the drive current. It is an example of the process which outputs the information which shows the magnitude
  • each segment of the ROM 42 is divided into units S corresponding to image areas to be described later so that image frames can be distinguished, and an extraction to be described later is performed in the LUT 42a.
  • Information indicating the relationship between the maximum gradation change and its response time, the start time of turn-off, the turn-off time, and the magnitude of the drive current may be stored, and the following processing may be performed.
  • the MPU 41 recognizes the image frames stored in the segments 420a to 420h separately for each unit S, and calculates the gradation of the image related to the unit S.
  • the unit S corresponds to an image area composed of a predetermined number of pixels. Examples of the gradation to be calculated include an average gradation of a pixel group constituting an image related to the unit S or a gradation of a pixel located at the center of the image related to the unit S.
  • the MPU 41 corresponds to the image area related to the unit S included in the segment 420a and the unit S included in the segment 420a, and changes the gradation between the image area related to the unit S included in the segment 421a. Calculation is performed for each S, and a gradation change that requires the most time for transition of the liquid crystal element, that is, a gradation change having the longest response time is extracted. For example, when the magnitude of the gradation change corresponds to the response time, the maximum gradation change is extracted. Note that the gradation change to be extracted may be a gradation change with the longest response time.
  • the MPU 41 similarly performs such extraction processing for the other segments 420b to 420h and 421b to 421h. Note that when the unit S corresponds to an image region composed of a single pixel, the gradation change is calculated for each pixel.
  • the MPU 41 refers to the LUT 42a, determines the response time corresponding to the extracted gradation change, acquires the turn-off start time, the turn-off time, and the magnitude of the drive current from the determined response time, and turns off the turn-off start time and the turn-off time.
  • Information indicating the time and the magnitude of the drive current is output to the backlight control unit 70.
  • FIG. 7 is a block diagram schematically showing the light source driving circuit 71.
  • the light source driving circuit 71 includes counters 75a to 75h corresponding to the light source units 5a to 5h, pulse generation circuits 76a to 76h, and LED drivers 77a to 77h having constant current circuits. Counters 75a to 75h, pulse generation circuits 76a to 76h, and LED drivers 77a to 77h are connected in series in this order.
  • the LED drivers 77a to 77h can turn on / off the light source units 5a to 5h and change the drive current based on a control signal input via an I2 C (Inter-Integrated Circuit) bus or the like.
  • the LED drivers 77a to 77h are connected to the light source units 5a to 5h, and a power source 80 is connected to the light source units 5a to 5h.
  • the constant current circuits of the LED drivers 77a to 77h are obtained by the control signal inputted through the I 2 C bus or the like as the information indicating the magnitude of the drive current corresponding to each of the light source units 5a to 5h acquired from the video analysis processing unit 40. For example, a drive current having a magnitude of E1 or E2 (see FIG. 8) described later is set.
  • the lighting period and the extinguishing period are determined by a PWM (PulseulWidth Modulation) signal output from the pulse generation circuits 76a to 76h, and the light source units 5a to 5h are turned on or off.
  • PWM PulseulWidth Modulation
  • the counters 75a to 75h receive the horizontal synchronization signal HS from the liquid crystal display panel timing generation unit 50, and receive the vertical synchronization signal VS from the liquid crystal display panel timing generation unit 50 via a frequency divider (not shown). Yes. In addition, the counters 75a to 75h have a period from when the vertical synchronization signal VS is input to the counters 75a to 75h, based on the information indicating the light extinction start time and the light extinction time acquired from the video analysis processing unit 40.
  • the number of pulses of the horizontal synchronization signal HS to be counted (hereinafter referred to as the first count number) and the number of pulses of the horizontal synchronization signal HS to be counted from the start of turning off to the end of turning off (hereinafter referred to as the second count number). Is called count number).
  • the counters 75a to 75h count the number of pulses of the horizontal synchronization signal HS using the input of the vertical synchronization signal VS as a trigger.
  • the counters 75a to 75h output the first signal to the pulse generation circuits 76a to 76h when the first count is finished after the vertical synchronization signal VS is input.
  • the counters 75a to 75h output the second signal to the pulse generation circuits 76a to 76h when the second count number is counted after the first count number is counted.
  • the pulse generation circuits 76a to 76h output low level signals to the LED drivers 77a to 77h when the first signal is input from the counters 75a to 75h.
  • the LED drivers 77a to 77h are turned off from when the low level signal is inputted, the current is cut off, and the light source units 5a to 5h are turned off.
  • the pulse generation circuits 76a to 76h output high level signals to the LED drivers 77a to 77h.
  • the LED drivers 77a to 77h are turned on when a high level signal is input, and the current set in the constant current circuits of the LED drivers 77a to 77h flows to the light source units 5a to 5h, and the light source units 5a to 5h. Lights up.
  • FIG. 8 is a timing chart showing the relationship between the vertical synchronization signal VS and the LED drivers 77a to 77h.
  • FIG. 8A shows a pulse wave of the vertical synchronization signal VS
  • V shown in FIG. 8A represents a cycle of the pulse wave.
  • FIG. 8B shows an on state and an off state of the LED drivers 77a to 77h.
  • H shown in FIG. 8B represents an on state
  • L represents an off state.
  • the height of the waveform in FIG. 8B indicates the magnitude of the current supplied from the power supply 80 to the light source units 5a to 5h.
  • FIG. 8B shows, as an example, an on state or an off state of the LED drivers 77a, 77b, 77c, and 77h.
  • a waveform 200 indicating the on state and the off state of 77a and 77h indicates a waveform when the response time before and after the transition is early when the image displayed on the liquid crystal display panel 1 transitions.
  • a broken line 150 indicates the on-state timing and the off-state timing when the response time is medium.
  • the light source units 5a and 5h are compared to when the response time is medium.
  • Pa indicates the off-state time in the waveform 200
  • Pb indicates the on-state time in the waveform 200.
  • Pa and Pb indicate substantially the same time.
  • E1 indicates the magnitude of the drive current when the light source units 5a and 5h are driven at the timing indicated by the waveform 200.
  • the transition time of the image corresponds to the transition time of the liquid crystal element.
  • a waveform 201 indicating the ON state and the OFF state of 77b and 77c indicates a waveform when the response time before and after the transition is slow when the image displayed on the liquid crystal display panel 1 transitions.
  • Qa represents the off-state time in the waveform 201
  • Qb represents the on-state time in the waveform 201
  • Qa is longer than Qb. That is, when the response time before and after the transition is slow, the turn-off time of the light source units 5b and 5c is longer than the turn-on time.
  • E2 indicates the magnitude of the drive current when the light source units 5b and 5c are driven at the timing indicated by the waveform 201, and is larger than E1.
  • the brightness of the light source units 5b and 5c at the time of lighting is normally darker as the turn-off time becomes longer.
  • the drive current E2 is larger than E1
  • the second part 1b and the third part corresponding to the light source units 5b and 5c since the drive current E2 is larger than E1, the second part 1b and the third part corresponding to the light source units 5b and 5c.
  • the luminance of 1c does not decrease compared to the luminance of the first portion 1a and the eighth portion 1h corresponding to the light source units 5a and 5h, and the luminance of the entire liquid crystal display panel 1 can be made uniform.
  • FIG. 9A is a schematic diagram illustrating the response characteristics of the liquid crystal display panel 1 when the image displayed on the liquid crystal display panel 1 transitions and the gradation of the image after the transition is high and the response time before and after the transition is fast. is there.
  • Reference numeral 300 denotes a characteristic curve indicating response characteristics.
  • FIG. 9B is a schematic diagram showing the response characteristics of the liquid crystal display panel when the image displayed on the liquid crystal display panel transitions and the gradation of the image after the transition is low and the response time before and after the transition is fast.
  • Reference numeral 301 denotes a characteristic curve indicating response characteristics.
  • the horizontal axis is an axis indicating the holding time for which the image is held in the liquid crystal display panel 1, and the vertical axis is an axis indicating the gradation.
  • a waveform 200 is shown in FIGS. 9A and 9B.
  • the characteristic curves 300 and 301 are rapidly increased or decreased from the current gradation toward the target gradation, and the target gradation is short-time.
  • the time point when the light source units 5a to 5h start to turn off is advanced by a predetermined time. For this reason, as indicated by the waveform 200, immediately after the change in gradation from the current gradation toward the target gradation is started in the first part 1a to the eighth part 1h, the light source units 5a to 5h are turned off and the target is turned off. Lights after the gradation is reached. For this reason, the user does not visually recognize the image while the image transitions in the first part 1a to the eighth part 1h, and can prevent the occurrence of a pseudo contour.
  • FIG. 10A is a schematic diagram showing the response characteristics of the liquid crystal display panel when the image displayed on the liquid crystal display panel transitions and the gradation of the image after the transition is high and the response time before and after the transition is slow.
  • Reference numeral 302 denotes a characteristic curve indicating response characteristics.
  • FIG. 10B is a schematic diagram showing the response characteristics of the liquid crystal display panel when the image displayed on the liquid crystal display panel transitions and the gradation of the image after the transition is low and the response time before and after the transition is slow.
  • Reference numeral 303 denotes a characteristic curve indicating response characteristics.
  • the horizontal axis is an axis indicating the holding time for which the image is held in the liquid crystal display panel 1
  • the vertical axis is an axis indicating the gradation.
  • a waveform 201 is shown in FIGS. 10A and 10B.
  • the characteristic curves 302 and 303 gradually increase or decrease from the current gradation toward the target gradation and reach the target gradation. Takes a long time.
  • the turn-off time Qa of the light source units 5a to 5h is longer than the turn-on time Qb. Therefore, as indicated by the waveform 201, the light source units 5a to 5h are turned off and turned off immediately after the change in gradation from the current gradation to the target gradation starts in the first part 1a to the eighth part 1h. Lights after time Qa has elapsed. For this reason, the user does not visually recognize the image until the transition of the image is almost completed in the first part 1a to the eighth part 1h, and the generation of the pseudo contour can be suppressed.
  • the gradation change between one image displayed sequentially and another image The response time corresponding to is calculated. Then, based on the calculated response time, the light source units 5a to 5h are set to the start time of turning off and the turn-off time. While the arrangement state of the liquid crystal elements is changed in the first portion 1a to the eighth portion 1h, Since the light source units 5a to 5h are turned off, even when the response time of the liquid crystal display panel 1 varies from part to part, generation of pseudo contours can be prevented and display quality can be improved.
  • a response time is calculated based on the gradation change, a turn-off time is determined according to the calculated response time, a drive current of the light source units 5a to 5h is controlled according to the determined turn-off time, and the liquid crystal Uniform brightness can be promoted throughout the display panel 1.
  • the drive current during lighting is increased to increase the luminance of the light source unit
  • the set turn-off time is short
  • the luminance of the light source unit is reduced by reducing the driving current at, so that the luminance is uniform while one image is held on the liquid crystal display panel 1.
  • the gradations of the first partial image and the second partial image displayed in the first part 1a to the eighth part 1h are obtained, and the light source units 5a to 5a are obtained based on the response times corresponding to the obtained gradation changes.
  • the lighting start time and the lighting time for 5 h are set, and the luminance of the entire liquid crystal display panel 1 is made uniform.
  • the gradation change of the first partial image and the second partial image displayed in the first part 1a to the eighth part 1h is obtained for each corresponding image area, and a predetermined magnitude is obtained from the obtained gradation changes.
  • the gradation change is extracted. For example, when the magnitude of the gradation change corresponds to the length of the response time, the maximum gradation change is extracted, and based on the response time (longest response time) corresponding to the extracted gradation change, the light source units 5a ⁇ 5 A light-off start point and a light-off time are set for 5h, and the light source units 5a to 5h are turned off until the response of the liquid crystal element is completed in the first part 1a to the eighth part 1h.
  • the gradation change to be extracted may be a gradation change with the longest response time.

Abstract

Provided is a liquid crystal display device which can prevent the generation of pseudo contours and improve display quality even when the response time of a liquid crystal display panel differs for each section. In a section of the liquid crystal display panel opposite light source units (5a-5h), transition time is calculated from grayscale changes of one image and another image which are sequentially displayed, the turn-off start time and turn-off period for the light source units (5a-5h) are set in accordance with the calculated transition time, and the light source units (5a-5h) are turned off while the arrangement state of liquid crystal elements is being changed in said section of the liquid crystal display panel.

Description

液晶表示装置Liquid crystal display
　本発明は、液晶の配列状態及び光源の点灯時間を制御する液晶表示装置に関する。 The present invention relates to a liquid crystal display device that controls the alignment state of liquid crystals and the lighting time of a light source.
　表示画面の大きさに比べて室内の占有面積が小さい液晶表示装置は、限られた室内空間を有効に利用することができることから、一般に広く普及している。液晶表示装置は、前キャビネットの内側に配置された映像を表示する液晶表示パネルに、後キャビネットに収容してある光源ユニットからの光を照射して、入力された画像情報（画像フレーム）に基づく画像を表示するように構成されている。 Liquid crystal display devices that occupy a small indoor area compared to the size of the display screen are widely used because they can effectively use a limited indoor space. The liquid crystal display device irradiates light from a light source unit accommodated in a rear cabinet to a liquid crystal display panel that displays an image arranged inside the front cabinet, and is based on input image information (image frame). It is configured to display an image.
　液晶表示パネルは、入力された画像フレームに基づく画像を所定時間保持するため、いわゆる動画ブレを生じやすく、該動画ブレを改善するために、光源ユニットを間欠的に消灯させる技術がある（例えば特許文献１参照）。該技術においては表示品位を高めるために、液晶表示パネルにて液晶素子の配列状態が変化している間は、光源ユニットを消灯し、液晶素子の配列状態の変化がいわゆる疑似輪郭としてユーザに視認されることを防ぐ必要がある。 Since the liquid crystal display panel holds an image based on an input image frame for a predetermined time, so-called moving image blur is likely to occur, and in order to improve the moving image blur, there is a technique of turning off the light source unit intermittently (for example, a patent) Reference 1). In this technique, in order to improve display quality, the light source unit is turned off while the liquid crystal element arrangement state is changing on the liquid crystal display panel, and the change in the arrangement state of the liquid crystal element is visually recognized by the user as a so-called pseudo contour. It is necessary to prevent it from being done.
特開２００９－１８０９３３号公報JP 2009-180933 A
　液晶表示パネルは、順次的に入力される画像フレームに基づいて画像を順次表示するが、一の画像と該一の画像の次に表示される他の画像との同一画素における階調変化は、画素毎に異なる。そのため画像の部分毎における階調変化に応じて、画像の各部分に対応する液晶表示パネルの各部分の応答時間も増減する。しかし特許文献１に記載の液晶表示装置は、光源ユニットの消灯開始時点及び消灯時間を示す固定値が予め設定してあり、画像の各部分における応答時間の差を考慮していない。 The liquid crystal display panel sequentially displays images based on sequentially input image frames. The gradation change in the same pixel between one image and another image displayed next to the one image is Different for each pixel. Therefore, the response time of each part of the liquid crystal display panel corresponding to each part of the image also increases or decreases according to the change in gradation in each part of the image. However, in the liquid crystal display device described in Patent Document 1, fixed values indicating the light extinction start time and the light extinction time of the light source unit are set in advance, and the difference in response time in each part of the image is not considered.
　その結果、液晶表示パネルの位置によっては、光源ユニットの消灯開始時点よりも早い時点で応答する場合があり、また消灯終了時点よりも遅い時点で応答が終了する場合がある。このため、液晶素子の配列状態が変化している途中で光源ユニットが点灯して、疑似輪郭が発生し、表示品位の低下を招来するという問題があった。 As a result, depending on the position of the liquid crystal display panel, there may be a response at a time earlier than the light source unit turn-off start time, and a response may be finished at a time later than the light turn-off end time. For this reason, there is a problem in that the light source unit is turned on while the alignment state of the liquid crystal elements is changing, a pseudo contour is generated, and the display quality is deteriorated.
　本発明は斯かる事情に鑑みてなされたものであり、液晶表示パネルの応答時間が部分毎に異なる場合でも、疑似輪郭の発生を防止し、表示品位の向上を図ることができる液晶表示装置を提供することを目的とする。 The present invention has been made in view of such circumstances, and even when the response time of the liquid crystal display panel varies from part to part, a liquid crystal display device capable of preventing the generation of pseudo contours and improving the display quality is provided. The purpose is to provide.
　本発明に係る液晶表示装置は、順次的に入力される画像を表示する液晶表示パネルと、該液晶表示パネルに対向して並設されており、前記液晶表示パネルに向けて光を出射する複数の光源とを備え、入力された画像が前記液晶表示パネルに表示される表示期間に前記複数の光源は間欠的に点灯する液晶表示装置において、前記液晶表示パネルにおける各光源との対向部分それぞれに表示される一の画像における第１部分画像及び次順の画像における第２部分画像の階調変化に基づいて、応答時間を算出する応答時間算出手段と、該応答時間算出手段にて算出された応答時間に基づいて、前記表示期間における前記光源の消灯期間を設定する消灯期間設定手段とを備えることを特徴とする。 The liquid crystal display device according to the present invention includes a liquid crystal display panel that displays sequentially input images, and a plurality of light sources that are arranged in parallel to face the liquid crystal display panel and emit light toward the liquid crystal display panel. In the liquid crystal display device in which the plurality of light sources are intermittently lit during a display period in which the input image is displayed on the liquid crystal display panel, each of the portions of the liquid crystal display panel facing each light source Based on the gradation change of the first partial image in the displayed one image and the second partial image in the next sequential image, the response time calculating means for calculating the response time and the response time calculating means And a light extinction period setting means for setting a light extinction period of the light source in the display period based on the response time.
　本発明においては、光源に対向する液晶表示パネルの各部分において、順次的に表示される一の画像と他の画像との階調変化に応じた液晶表示パネルの応答時間を算出し、算出した応答時間に基づいて、前記光源の消灯期間を設定し、液晶表示パネルの前記部分にて液晶素子の配列状態が変化している間は、前記光源を消灯させる。 In the present invention, in each part of the liquid crystal display panel facing the light source, the response time of the liquid crystal display panel corresponding to the change in gradation between one image displayed sequentially and the other image is calculated and calculated. Based on the response time, an extinguishing period of the light source is set, and the light source is extinguished while the arrangement state of the liquid crystal elements is changed in the portion of the liquid crystal display panel.
　本発明に係る液晶表示装置は、前記応答時間算出手段は、前記両部分画像の階調変化を算出するようにしてあることを特徴とする。 The liquid crystal display device according to the present invention is characterized in that the response time calculation means calculates a change in gradation between the two partial images.
　本発明においては、第１部分画像及び第２部分画像の階調変化を求め、求めた階調変化に基づいて、第１部分画像及び第２部分画像に対応する位置における液晶表示パネルの応答時間を算出する。 In the present invention, the gradation change of the first partial image and the second partial image is obtained, and the response time of the liquid crystal display panel at the position corresponding to the first partial image and the second partial image is obtained based on the obtained gradation change. Is calculated.
　本発明に係る液晶表示装置は、前記応答時間算出手段は、前記第１部分画像を構成する複数の画像領域それぞれと前記第１部分画像を構成する複数の画像領域に対応し、前記第２部分画像を構成する複数の画像領域それぞれとの階調変化を対応する画像領域毎に求める手段と、該手段にて求めた複数の階調変化に基づいて応答時間の最大値を抽出する手段とを備えることを特徴とする。 In the liquid crystal display device according to the present invention, the response time calculation unit corresponds to each of a plurality of image areas constituting the first partial image and a plurality of image areas constituting the first partial image, and the second part Means for obtaining a gradation change with each of a plurality of image areas constituting the image for each corresponding image area, and means for extracting the maximum value of the response time based on the plurality of gradation changes obtained by the means. It is characterized by providing.
　本発明においては、液晶表示パネルの各部分にて表示される第１部分画像及び第２部分画像の階調変化を、対応する画像領域毎に求め、求めた最大の階調変化に基づいて、前記光源の消灯期間を設定し、液晶表示パネルの各部分にて液晶素子の応答が終了するまで、光源を消灯させる。 In the present invention, the gradation change of the first partial image and the second partial image displayed in each part of the liquid crystal display panel is obtained for each corresponding image area, and based on the obtained maximum gradation change, The light source extinction period is set, and the light source is extinguished until the response of the liquid crystal element is finished in each part of the liquid crystal display panel.
　本発明に係る液晶表示装置は、前記応答時間算出手段にて算出された応答時間に基づいて、前記対向部分に対向する前記光源の駆動電流を制御する電流値制御手段を備えることを特徴とする。 The liquid crystal display device according to the present invention includes current value control means for controlling the drive current of the light source facing the facing portion based on the response time calculated by the response time calculation means. .
　本発明においては、応答時間に基づいて設定された消灯期間に対応させて、前記光源の駆動電流を制御し、液晶表示パネル全体での輝度の均一化を促進する。 In the present invention, the driving current of the light source is controlled in correspondence with the extinguishing period set based on the response time, and the uniformization of the luminance in the entire liquid crystal display panel is promoted.
　本発明に係る液晶表示装置は、前記電流値制御手段は、前記消灯期間設定手段によって設定された前記消灯期間の長短に応じて、駆動電流を増減させるようにしてあることを特徴とする。 The liquid crystal display device according to the present invention is characterized in that the current value control means increases or decreases the drive current according to the length of the extinction period set by the extinction period setting means.
　本発明においては、液晶表示パネルの各部分において、設定された消灯期間が長い場合、点灯時における駆動電流を増加させて光源の輝度を大きくし、設定された消灯期間が短い場合、点灯時における駆動電流を減少させて光源の輝度を小さくして、液晶表示パネルに画像が保持される期間（表示期間）の輝度を均一化する。 In the present invention, in each part of the liquid crystal display panel, when the set extinction period is long, the drive current at the time of lighting is increased to increase the luminance of the light source, and when the set extinction period is short, at the time of lighting The drive current is reduced to reduce the luminance of the light source, and the luminance during the period in which the image is held on the liquid crystal display panel (display period) is made uniform.
　本発明に係る液晶表示装置にあっては、光源に対向する液晶表示パネルの各部分において、順次的に表示される一の画像と次の画像との階調変化に応じた応答時間を算出する。そして算出した応答時間に基づいて、前記光源の消灯期間を設定し、液晶表示パネルの各部分にて液晶素子の配列状態が変化している間は、前記光源を消灯させるので、液晶表示パネルの応答時間が部分毎に異なる場合でも、疑似輪郭の発生を防止し、表示品位の向上を図ることができる。 In the liquid crystal display device according to the present invention, in each part of the liquid crystal display panel facing the light source, the response time corresponding to the gradation change between the sequentially displayed one image and the next image is calculated. . Based on the calculated response time, the light source is turned off, and the light source is turned off while the arrangement state of the liquid crystal elements is changing in each part of the liquid crystal display panel. Even when the response time varies from part to part, it is possible to prevent the occurrence of pseudo contours and improve the display quality.
液晶表示装置の外観を示す斜視図である。It is a perspective view which shows the external appearance of a liquid crystal display device. 光源ユニットを略示する正面図である。It is a front view which briefly shows a light source unit. バックライト制御部及び映像処理部付近の構成を略示するブロック図である。It is a block diagram which briefly shows the structure near a backlight control part and a video processing part. 映像解析処理部の構成を略示するブロック図である。It is a block diagram which briefly shows the structure of a video analysis processing part. ＲＯＭの一の構成例を示す概念図である。It is a conceptual diagram which shows one structural example of ROM. ＲＯＭの他の構成例を示す概念図である。It is a conceptual diagram which shows the other structural example of ROM. 光源駆動回路を略示するブロック図である。FIG. 3 is a block diagram schematically showing a light source driving circuit. 垂直同期信号とＬＥＤドライバとの関係を示すタイミングチャートである。It is a timing chart which shows the relationship between a vertical synchronizing signal and an LED driver. 液晶表示パネルに表示される画像が遷移する場合において、遷移後の画像の階調が高く、遷移前後の応答時間が早い場合における液晶表示パネルの応答特性を示す模式図である。When the image displayed on a liquid crystal display panel changes, it is a schematic diagram which shows the response characteristic of a liquid crystal display panel in case the gradation of the image after a transition is high and the response time before and behind a transition is early. 液晶表示パネルに表示される画像が遷移する場合において、遷移後の画像の階調が低く、遷移前後の応答時間が早い場合における液晶表示パネルの応答特性を示す模式図である。When the image displayed on a liquid crystal display panel changes, it is a schematic diagram which shows the response characteristic of a liquid crystal display panel in case the gradation of the image after a transition is low and the response time before and behind a transition is early. 液晶表示パネルに表示される画像が遷移する場合において、遷移後の画像の階調が高く、遷移前後の応答時間が遅い場合における液晶表示パネルの応答特性を示す模式図である。When the image displayed on a liquid crystal display panel changes, it is a schematic diagram which shows the response characteristic of a liquid crystal display panel in case the gradation of the image after a transition is high and the response time before and behind a transition is slow. 液晶表示パネルに表示される画像が遷移する場合において、遷移後の画像の階調が低く、遷移前後の応答時間が遅い場合における液晶表示パネルの応答特性を示す模式図である。When the image displayed on a liquid crystal display panel changes, it is a schematic diagram which shows the response characteristic of a liquid crystal display panel in case the gradation of the image after a transition is low and the response time before and behind a transition is slow.
　以下本発明を実施の形態に係る液晶表示装置を示す図面に基づいて詳述する。図１は液晶表示装置の外観を示す斜視図、図２は光源ユニットを略示する正面図である。 Hereinafter, the present invention will be described in detail with reference to the drawings showing a liquid crystal display device according to an embodiment. FIG. 1 is a perspective view showing an appearance of a liquid crystal display device, and FIG. 2 is a front view schematically showing a light source unit.
　図において１は液晶及びＴＦＴ(Thin Film Transistor)を備える矩形の液晶表示パネルである。該液晶表示パネル１は、ＴＦＴの動作を制御することによって液晶への印加電圧を制御し、液晶素子の配列状態を変化させて光の透過率を調整する。光の透過率を調整することによって、液晶表示パネル１の前面に所定の映像が表示される。 In the figure, reference numeral 1 denotes a rectangular liquid crystal display panel having liquid crystal and TFT (Thin Film Transistor). The liquid crystal display panel 1 controls the voltage applied to the liquid crystal by controlling the operation of the TFT, and changes the alignment state of the liquid crystal elements to adjust the light transmittance. By adjusting the light transmittance, a predetermined image is displayed on the front surface of the liquid crystal display panel 1.
　液晶表示パネル１は、前保持枠体と後保持枠体と（いずれも図示せず）によって、その周縁部が挟持されており、矩形枠状の前キャビネット２に収容されている。前キャビネット２は前保持枠体及び後保持枠体の周囲に配置されている。前キャビネット２は矩形の開口を備えており、該開口の寸法は液晶表示パネル１に対応した寸法となっている。 The liquid crystal display panel 1 has a peripheral edge sandwiched between a front holding frame and a rear holding frame (both not shown), and is housed in a rectangular frame-shaped front cabinet 2. The front cabinet 2 is disposed around the front holding frame and the rear holding frame. The front cabinet 2 has a rectangular opening, and the dimension of the opening corresponds to the liquid crystal display panel 1.
　液晶表示パネル１の後側には、矩形板状のバックライトシャーシ４が配設してある。該バックライトシャーシ４の前部にて、複数の（本実施例においては８個の）光源ユニット５ａ～５ｈが支持されている。光源ユニット５ａ～５ｈ及びバックライトシャーシ４は、後キャビネット３に収容されている。なお後キャビネット３の前縁部は図示しない係合凸部を備え、前キャビネット２の後縁部は図示しない係合凹部を備えており、該係合凹部及び係合凸部を係合させて、前キャビネット２と後キャビネット３とが連結してある。 A rectangular plate-like backlight chassis 4 is disposed on the rear side of the liquid crystal display panel 1. A plurality (eight in this embodiment) of light source units 5a to 5h are supported at the front portion of the backlight chassis 4. The light source units 5 a to 5 h and the backlight chassis 4 are accommodated in the rear cabinet 3. The front edge of the rear cabinet 3 is provided with an engaging convex part (not shown), and the rear edge part of the front cabinet 2 is provided with an engaging concave part (not shown). The engaging concave part and the engaging convex part are engaged with each other. The front cabinet 2 and the rear cabinet 3 are connected.
　光源ユニット５ａ～５ｈは上下に並んでおり、光源ユニット５ａは最も上に位置し、光源ユニット５ｈは最も下に位置する。光源ユニット５ａ～５ｈは、矩形横長の基板５０と、該基板５０に実装された複数のＬＥＤ(Light Emitting Diode)５１、５１、・・・、５１とを備えている。ＬＥＤ５１、５１、・・・、５１は、基板５０上にて等間隔を空けて横方向に並んでおり、相互に直列接続されている。なお光源ユニット５ａ～５ｈそれぞれに対向する液晶表示パネル１の各部分を、図１において第１部分１ａ～第８部分１ｈとして示している。 The light source units 5a to 5h are lined up and down, with the light source unit 5a positioned at the top and the light source unit 5h positioned at the bottom. The light source units 5a to 5h include a rectangular horizontally long substrate 50 and a plurality of LEDs (Light Emitting Diodes) 51, 51,... 51 mounted on the substrate 50. The LEDs 51, 51,..., 51 are arranged in the horizontal direction at equal intervals on the substrate 50, and are connected in series. Each part of the liquid crystal display panel 1 facing the light source units 5a to 5h is shown as a first part 1a to an eighth part 1h in FIG.
　バックライトシャーシ４の後側には、ＬＥＤ５１の駆動を制御するバックライト制御部７０及び液晶表示パネル１に入力される画像フレームに種々の処理を施す映像処理部１０などが設けてある。図３はバックライト制御部７０及び映像処理部１０付近の構成を略示するブロック図である。 On the rear side of the backlight chassis 4, there are provided a backlight control unit 70 that controls driving of the LEDs 51, a video processing unit 10 that performs various processes on an image frame input to the liquid crystal display panel 1, and the like. FIG. 3 is a block diagram schematically showing the configuration in the vicinity of the backlight control unit 70 and the video processing unit 10.
　液晶表示パネル１には、映像処理部１０、倍速処理部２０、ＯＳ(Over Shoot)処理部３０、映像解析処理部４０及び液晶表示パネルタイミング生成部５０を経て、画像フレームが入力される。
　映像処理部１０には、図示しないチューナ及びＨＤＭＩ(High Definition Multimedia Interface)などの端子から画像を示す画像フレームが入力される。映像処理部１０は、入力された画像フレームに対してコントラスト補正及び色補正処理などを実行し、倍速処理部２０に出力する。 An image frame is input to the liquid crystal display panel 1 through a video processing unit 10, a double speed processing unit 20, an OS (Over Shoot) processing unit 30, a video analysis processing unit 40, and a liquid crystal display panel timing generation unit 50.
An image frame indicating an image is input to the video processing unit 10 from a terminal (not shown) such as a tuner and HDMI (High Definition Multimedia Interface). The video processing unit 10 performs contrast correction, color correction processing, and the like on the input image frame, and outputs the result to the double speed processing unit 20.
　倍速処理部２０は、入力された画像フレームに基づいて、所定時間内に送信される画像の数を倍加する処理を実行し、ＯＳ処理部３０へ画像フレームを出力する。
　ＯＳ処理部３０は、入力された画像フレームに係る信号に対し、オーバーシュート又はアンダーシュートを発生させて加算する処理を実行し、映像解析処理部４０へ画像フレームを出力する。 The double speed processing unit 20 executes a process of doubling the number of images transmitted within a predetermined time based on the input image frame, and outputs the image frame to the OS processing unit 30.
The OS processing unit 30 performs processing for generating and adding overshoot or undershoot to the signal related to the input image frame, and outputs the image frame to the video analysis processing unit 40.
　映像解析処理部４０は、順次的に入力された画像フレームに基づいて、一の画像と、該一の画像の次に液晶表示パネル１に表示される他の画像との間の階調変化に基づく応答時間を、光源ユニット５ａ～５ｈに対応する画像部分毎に算出し、算出した応答時間に基づいて、液晶表示パネル１に一つの画像が保持される期間（表示期間）における光源ユニット５ａ～５ｈそれぞれの消灯開始時点及び消灯時間を求め、また光源ユニット５ａ～５ｈそれぞれの駆動電流の大きさを求めて、求めた消灯開始時点、消灯時間及び駆動電流の大きさを示す情報をバックライト制御部７０に出力する。 Based on the sequentially input image frames, the video analysis processing unit 40 changes the gradation between one image and another image displayed on the liquid crystal display panel 1 next to the one image. Based on the calculated response time, a response time based on the light source units 5a to 5h is calculated, and based on the calculated response time, the light source units 5a to 5a in a period (display period) in which one image is held in the liquid crystal display panel 1 are calculated. 5h to determine the turn-off start time and turn-off time of each light source unit 5a to 5h, obtain the drive current magnitude of each of the light source units 5a to 5h, and backlight control information indicating the obtained turn-off start time, turn-off time and drive current magnitude To the unit 70.
　ここで階調変化とは、変化前後の各階調値に依存する数値であって、液晶素子の遷移時間に対応する数値をいい、変化前の階調値と変化後の階調値との差（絶対値）を意味しない。例えば階調値１２８から階調値０に階調が変化する場合における液晶素子の遷移時間と、階調値２２８から階調値１００に階調値が変化する場合における液晶素子の遷移時間とが異なる場合、前者における絶対値と後者における絶対値とは等しいが、前者における階調変化と後者における階調変化とは異なる。
　なお階調変化は種々の計算方法に基づいて求められる。例えば、変化前後の各階調値に所定の補正係数を乗じてそれぞれ算出し、算出した各値に基づいて階調変化を求めることができる。また変化前後の各階調値を所定の関数に適用してそれぞれ算出し、算出した各値に基づいて階調変化を求めてもよい。いずれの場合においても算出後の各値の差分又は除算結果を階調変化として求めることができる。 Here, the gradation change is a numerical value that depends on each gradation value before and after the change, and corresponds to the transition time of the liquid crystal element, and the difference between the gradation value before the change and the gradation value after the change. Does not mean (absolute value). For example, the transition time of the liquid crystal element when the gradation changes from the gradation value 128 to the gradation value 0 and the transition time of the liquid crystal element when the gradation value changes from the gradation value 228 to the gradation value 100 If they are different, the absolute value in the former is equal to the absolute value in the latter, but the gradation change in the former and the gradation change in the latter are different.
Note that the gradation change can be obtained based on various calculation methods. For example, each gradation value before and after the change can be calculated by multiplying each gradation value by a predetermined correction coefficient, and the gradation change can be obtained based on each calculated value. Alternatively, each gradation value before and after the change may be calculated by applying it to a predetermined function, and the gradation change may be obtained based on each calculated value. In either case, the difference between the calculated values or the division result can be obtained as a gradation change.
　バックライト制御部７０は、図示しないＭＰＵ(Micro Processing Unit)、ＲＯＭ(Read Only Memory)、ＲＡＭ(Random Access Memory)を備え、更に光源ユニット５ａ～５ｈを駆動する光源駆動回路７１を備える。バックライト制御部７０のＭＰＵは、入力された消灯開始時点、消灯時間及び駆動電流の大きさを示す情報に基づいて、光源駆動回路７１の動作を制御し、光源ユニット５ａ～５ｈの駆動を制御する。 The backlight control unit 70 includes an MPU (Micro Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) (not shown), and further includes a light source driving circuit 71 that drives the light source units 5a to 5h. The MPU of the backlight control unit 70 controls the operation of the light source drive circuit 71 based on the input information indicating the start time of turn-off, the turn-off time, and the magnitude of the drive current, and controls the drive of the light source units 5a to 5h. To do.
　前記映像解析処理部４０は、画像フレームを液晶表示パネルタイミング生成部５０に出力する。液晶表示パネルタイミング生成部５０は、図示しないクロックを備えており、該クロックの計時結果に基づいて、液晶表示パネルタイミング生成部５０に垂直同期信号ＶＳ及び水平同期信号ＨＳを出力する。また液晶表示パネルタイミング生成部５０は、液晶表示パネル１に画像フレームを出力する。 The video analysis processing unit 40 outputs the image frame to the liquid crystal display panel timing generation unit 50. The liquid crystal display panel timing generation unit 50 includes a clock (not shown), and outputs a vertical synchronization signal VS and a horizontal synchronization signal HS to the liquid crystal display panel timing generation unit 50 based on the clocking result of the clock. The liquid crystal display panel timing generation unit 50 outputs an image frame to the liquid crystal display panel 1.
　なお垂直同期信号ＶＳ及び水平同期信号ＨＳはパルス波であり、垂直同期信号ＶＳのパルス波の周期は、液晶表示パネルタイミング生成部５０から画像フレームが出力される周期に等しい。液晶表示パネル１は、液晶表示パネルタイミング生成部５０から入力された画像フレームに基づいて画像を表示し、垂直同期信号ＶＳのパルス波が入力されてから次のパルス波が入力されるまでの間、同じ画像を保持する。 Note that the vertical synchronization signal VS and the horizontal synchronization signal HS are pulse waves, and the period of the pulse wave of the vertical synchronization signal VS is equal to the period in which the image frame is output from the liquid crystal display panel timing generation unit 50. The liquid crystal display panel 1 displays an image based on the image frame input from the liquid crystal display panel timing generation unit 50, and after the pulse wave of the vertical synchronization signal VS is input until the next pulse wave is input. , Keep the same image.
　次に映像解析処理部４０の構成を説明する。図４は、映像解析処理部４０の構成を略示するブロック図、図５はＲＯＭの一の構成例を示す概念図、図６はＲＯＭの他の構成例を示す概念図である。 Next, the configuration of the video analysis processing unit 40 will be described. FIG. 4 is a block diagram schematically showing the configuration of the video analysis processing unit 40, FIG. 5 is a conceptual diagram showing one configuration example of the ROM, and FIG. 6 is a conceptual diagram showing another configuration example of the ROM.
　映像解析処理部４０は、共通バスを介して相互に接続されたＭＰＵ４１、制御プログラムを格納したＲＯＭ４２、情報を一時的に格納するＲＡＭ４３、入力Ｉ／Ｆ(InterFace)４４及び出力Ｉ／Ｆ４５を備えている。ＭＰＵ４１は、ＲＯＭ４２に格納した制御プログラムをＲＡＭ４３に読出して実行する。 The video analysis processing unit 40 includes an MPU 41, a ROM 42 that stores a control program, a RAM 43 that temporarily stores information, an input I / F (InterFace) 44, and an output I / F 45 that are mutually connected via a common bus. ing. The MPU 41 reads the control program stored in the ROM 42 into the RAM 43 and executes it.
　映像解析処理部４０には、入力Ｉ／Ｆ４４を介してＯＳ処理部３０から画像フレームが入力される。また出力Ｉ／Ｆ４５を介して液晶表示パネルタイミング生成部５０に画像フレームが出力され、バックライト制御部７０に、光源ユニット５ａ～５ｈそれぞれの消灯開始時点及び消灯時間を示す情報、及び光源ユニット５ａ～５ｈそれぞれの駆動電流の大きさを示す情報が出力される。 The image analysis processor 40 receives an image frame from the OS processor 30 via the input I / F 44. Further, an image frame is output to the liquid crystal display panel timing generation unit 50 via the output I / F 45, and information indicating the turn-off start time and turn-off time of each of the light source units 5a to 5h and the light source unit 5a are output to the backlight control unit 70. Information indicating the magnitude of each of the drive currents for up to 5 hours is output.
　ＲＯＭ４２は、後述する階調変化と該階調変化に対応する応答時間、消灯開始時点、消灯時間及び駆動電流の大きさとの関係を示すＬＵＴ(Look Up Table)４２ａを備えている。ＲＯＭ４２には、ＯＳ処理部３０から順次的に入力される画像フレーム毎に記憶領域４２０、４２１、・・・が設定される。該記憶領域４２０、４２１、・・・は、前述した第１部分１ａ～第８部分１ｈそれぞれに対応するセグメントを含んでいる。 The ROM 42 includes a look-up table (LUT) 42a indicating the relationship between a gradation change described later and a response time corresponding to the gradation change, a turn-off start time, a turn-off time, and the magnitude of the drive current. In the ROM 42, storage areas 420, 421,... Are set for each image frame sequentially input from the OS processing unit 30. The storage areas 420, 421,... Include segments corresponding to the first part 1a to the eighth part 1h described above.
　ＭＰＵ４１は、画像フレームを分割して記憶領域の各セグメントに記憶する。そしてＭＰＵ４１は、順次的に入力される画像フレーム間における階調変化をセグメント毎に求め、求めた階調変化に基づいて応答時間を算出し、消灯開始時点、消灯時間及び駆動電流の大きさを示す情報を生成してバックライト制御部７０に出力する。 The MPU 41 divides the image frame and stores it in each segment of the storage area. Then, the MPU 41 obtains a gradation change between sequentially input image frames for each segment, calculates a response time based on the obtained gradation change, and calculates the turn-off start time, the turn-off time, and the magnitude of the drive current. Information is generated and output to the backlight control unit 70.
　例えばＭＰＵ４１は、入力された画像フレームに係る一の画像を示す情報を第１部分１ａ～第８部分１ｈに対応させて分割し、分割した情報を記憶領域４２０の各セグメント４２０ａ～４２０ｈに記憶する。また一の画像の次に液晶表示パネル１に表示される他の画像を示す画像フレームを第１部分１ａ～第８部分１ｈそれぞれに対応させて分割し、分割した画像フレームを記憶領域４２１の各セグメント４２１ａ～４２１ｈに記憶する。 For example, the MPU 41 divides information indicating one image related to the input image frame so as to correspond to the first part 1a to the eighth part 1h, and stores the divided information in the segments 420a to 420h of the storage area 420. . In addition, an image frame indicating another image displayed on the liquid crystal display panel 1 next to one image is divided corresponding to each of the first part 1a to the eighth part 1h, and the divided image frame is divided into each of the storage areas 421. Store in segments 421a-421h.
　ＭＰＵ４１は、各セグメント４２０ａ～４２０ｈに記憶した画像フレームに基づいて、第１部分１ａ～第８部分１ｈそれぞれに表示される一の画像を構成する部分的な画像（第１部分画像）の階調を、第１部分１ａ～第８部分１ｈそれぞれについて算出する。また各セグメント４２１ａ～４２１ｈに記憶した画像フレームに基づいて、第１部分１ａ～第８部分１ｈそれぞれに表示される他の画像を構成する部分的な画像（第２部分画像）の階調を、第１部分１ａ～第８部分１ｈそれぞれについて算出する。なお算出する階調としては、第１部分１ａ～第８部分１ｈを構成する画素群の平均階調又は各部分の中央に位置する画素の階調などが挙げられる。そして第１部分１ａ～第８部分１ｈそれぞれについて、対応する第１部分画像及び第２部分画像の階調変化を求める。 Based on the image frames stored in the segments 420a to 420h, the MPU 41 performs gradation of partial images (first partial images) constituting one image displayed in each of the first part 1a to the eighth part 1h. Are calculated for each of the first part 1a to the eighth part 1h. Further, based on the image frames stored in the segments 421a to 421h, the gradations of partial images (second partial images) constituting other images displayed in the first part 1a to the eighth part 1h, respectively, Calculation is performed for each of the first part 1a to the eighth part 1h. Examples of the calculated gradation include the average gradation of the pixel group constituting the first part 1a to the eighth part 1h or the gradation of the pixel located at the center of each part. Then, for each of the first part 1a to the eighth part 1h, the gradation change of the corresponding first partial image and second partial image is obtained.
　次にＭＰＵ４１は、ＬＵＴ４２ａを参照し、求めた階調変化に対応する応答時間を決定し、決定した応答時間から消灯開始時点、消灯時間及び駆動電流の大きさを取得して、消灯開始時点、消灯時間及び駆動電流の大きさを示す情報をバックライト制御部７０に出力する。ＬＵＴ４２ａには、第１部分１ａ～第８部分１ｈそれぞれについて、例えば応答時間が小さくなるに従って消灯開始時点が早くなることを示す情報が格納してあり、また応答時間が大きくなるに従って駆動電流の大きさが大きくなることを示す情報が格納してある。 Next, the MPU 41 refers to the LUT 42a, determines the response time corresponding to the obtained gradation change, acquires the turn-off start time, the turn-off time, and the magnitude of the drive current from the determined response time, Information indicating the turn-off time and the magnitude of the drive current is output to the backlight control unit 70. The LUT 42a stores, for example, information indicating that the turn-off start time becomes earlier as the response time becomes smaller for each of the first part 1a to the eighth part 1h, and the drive current increases as the response time becomes larger. Stores information indicating that the size increases.
　なお階調変化に基づいて応答時間を算出し、消灯開始時点、消灯時間及び駆動電流の大きさを示す情報をバックライト制御部７０に出力する上記処理は、消灯開始時点、消灯時間及び駆動電流の大きさを示す情報をバックライト制御部７０に出力する処理の一例であって、これに限定されるものではない。 Note that the above processing for calculating the response time based on the gradation change and outputting information indicating the magnitude of the light extinction start time, the light extinction time, and the drive current to the backlight control unit 70 includes the light extinction start time, the extinction time, and the drive current. It is an example of the process which outputs the information which shows the magnitude | size to the backlight control part 70, Comprising: It is not limited to this.
　例えば図６の破線にて示すように、ＲＯＭ４２の各セグメントを、後述する画像領域に対応する単位Ｓに分割して、画像フレームを区別することができるように構成し、ＬＵＴ４２ａに、後述する抽出した最大の階調変化とその応答時間、消灯開始時点、消灯時間及び駆動電流の大きさとの関係を示す情報を格納して、以下に示すような処理を行ってもよい。 For example, as shown by a broken line in FIG. 6, each segment of the ROM 42 is divided into units S corresponding to image areas to be described later so that image frames can be distinguished, and an extraction to be described later is performed in the LUT 42a. Information indicating the relationship between the maximum gradation change and its response time, the start time of turn-off, the turn-off time, and the magnitude of the drive current may be stored, and the following processing may be performed.
　ＭＰＵ４１は、各セグメント４２０ａ～４２０ｈに記憶した画像フレームを単位Ｓ毎に区別して認識し、単位Ｓに係る画像の階調を算出する。なお単位Ｓは、所定数の画素からなる画像領域に対応している。算出する階調としては、単位Ｓに係る画像を構成する画素群の平均階調又は単位Ｓに係る画像の中央に位置する画素の階調などが挙げられる。 The MPU 41 recognizes the image frames stored in the segments 420a to 420h separately for each unit S, and calculates the gradation of the image related to the unit S. The unit S corresponds to an image area composed of a predetermined number of pixels. Examples of the gradation to be calculated include an average gradation of a pixel group constituting an image related to the unit S or a gradation of a pixel located at the center of the image related to the unit S.
　ＭＰＵ４１は、セグメント４２０ａに含まれる単位Ｓに係る画像領域と、セグメント４２０ａに含まれる単位Ｓに対応しており、セグメント４２１ａに含まれる単位Ｓに係る画像領域との階調変化を、対応する単位Ｓ毎に算出し、液晶素子の遷移に最も時間を要する階調変化、すなわち応答時間が最長の階調変化を抽出する。例えば階調変化の大小が応答時間の長短に対応する場合、最大の階調変化を抽出する。なお抽出する階調変化は、応答時間が最長となる階調変化であればよい。ＭＰＵ４１は、このような抽出処理を他のセグメント４２０ｂ～４２０ｈ、４２１ｂ～４２１ｈに対しても同様に実行する。なお単位Ｓが単一の画素からなる画像領域に対応している場合、画素毎に階調変化を算出する。 The MPU 41 corresponds to the image area related to the unit S included in the segment 420a and the unit S included in the segment 420a, and changes the gradation between the image area related to the unit S included in the segment 421a. Calculation is performed for each S, and a gradation change that requires the most time for transition of the liquid crystal element, that is, a gradation change having the longest response time is extracted. For example, when the magnitude of the gradation change corresponds to the response time, the maximum gradation change is extracted. Note that the gradation change to be extracted may be a gradation change with the longest response time. The MPU 41 similarly performs such extraction processing for the other segments 420b to 420h and 421b to 421h. Note that when the unit S corresponds to an image region composed of a single pixel, the gradation change is calculated for each pixel.
　そしてＭＰＵ４１は、ＬＵＴ４２ａを参照し、抽出した階調変化に対応する応答時間を決定し、決定した応答時間から消灯開始時点、消灯時間及び駆動電流の大きさを取得して、消灯開始時点、消灯時間及び駆動電流の大きさを示す情報をバックライト制御部７０に出力する。 Then, the MPU 41 refers to the LUT 42a, determines the response time corresponding to the extracted gradation change, acquires the turn-off start time, the turn-off time, and the magnitude of the drive current from the determined response time, and turns off the turn-off start time and the turn-off time. Information indicating the time and the magnitude of the drive current is output to the backlight control unit 70.
　次に光源駆動回路７１の構成について説明する。図７は光源駆動回路７１を略示するブロック図である。光源駆動回路７１は、光源ユニット５ａ～５ｈに対応するカウンタ７５ａ～７５ｈ、パルス発生回路７６ａ～７６ｈ、及び定電流回路を有するＬＥＤドライバ７７ａ～７７ｈを備えている。カウンタ７５ａ～７５ｈ、パルス発生回路７６ａ～７６ｈ及びＬＥＤドライバ７７ａ～７７ｈはこの順に直列に接続してある。 Next, the configuration of the light source driving circuit 71 will be described. FIG. 7 is a block diagram schematically showing the light source driving circuit 71. The light source driving circuit 71 includes counters 75a to 75h corresponding to the light source units 5a to 5h, pulse generation circuits 76a to 76h, and LED drivers 77a to 77h having constant current circuits. Counters 75a to 75h, pulse generation circuits 76a to 76h, and LED drivers 77a to 77h are connected in series in this order.
　ＬＥＤドライバ７７ａ～７７ｈは、Ｉ2 Ｃ(Inter-Integrated Circuit)バス等を介して入力される制御信号に基づいて、光源ユニット５ａ～５ｈのオン／オフ、駆動電流の変更を行うことができる。またＬＥＤドライバ７７ａ～７７ｈは、光源ユニット５ａ～５ｈに接続してあり、光源ユニット５ａ～５ｈには電源８０が接続されている。 The LED drivers 77a to 77h can turn on / off the light source units 5a to 5h and change the drive current based on a control signal input via an I2 C (Inter-Integrated Circuit) bus or the like. The LED drivers 77a to 77h are connected to the light source units 5a to 5h, and a power source 80 is connected to the light source units 5a to 5h.
　映像解析処理部４０から取得した各光源ユニット５ａ～５ｈに対応する駆動電流の大きさを示す情報が、Ｉ2 Ｃバス等を介して入力される制御信号によって、ＬＥＤドライバ７７ａ～７７ｈの定電流回路に設定され、例えば後述するＥ１又はＥ２の大きさ（図８参照）の駆動電流が設定される。またパルス発生回路７６ａ～７６ｈから出力されるＰＷＭ(Pulse Width Modulation)信号によって、点灯期間及び消灯期間が決定され、各光源ユニット５ａ～５ｈが点灯又は消灯する。 The constant current circuits of the LED drivers 77a to 77h are obtained by the control signal inputted through the I 2 C bus or the like as the information indicating the magnitude of the drive current corresponding to each of the light source units 5a to 5h acquired from the video analysis processing unit 40. For example, a drive current having a magnitude of E1 or E2 (see FIG. 8) described later is set. The lighting period and the extinguishing period are determined by a PWM (PulseulWidth Modulation) signal output from the pulse generation circuits 76a to 76h, and the light source units 5a to 5h are turned on or off.
　カウンタ７５ａ～７５ｈには、液晶表示パネルタイミング生成部５０から水平同期信号ＨＳが入力されており、また液晶表示パネルタイミング生成部５０から図示しない分周器を介して垂直同期信号ＶＳが入力されている。またカウンタ７５ａ～７５ｈには、映像解析処理部４０から取得した消灯開始時点及び消灯時間を示す情報に基づいて、カウンタ７５ａ～７５ｈについて、垂直同期信号ＶＳが入力されてから消灯を開始するまでに数えるべき水平同期信号ＨＳのパルス数のカウント数（以下第１カウント数という）と、消灯を開始してから消灯を終了するまでに数えるべき水平同期信号ＨＳのパルス数のカウント数（以下第２カウント数という）とが設定される。 The counters 75a to 75h receive the horizontal synchronization signal HS from the liquid crystal display panel timing generation unit 50, and receive the vertical synchronization signal VS from the liquid crystal display panel timing generation unit 50 via a frequency divider (not shown). Yes. In addition, the counters 75a to 75h have a period from when the vertical synchronization signal VS is input to the counters 75a to 75h, based on the information indicating the light extinction start time and the light extinction time acquired from the video analysis processing unit 40. The number of pulses of the horizontal synchronization signal HS to be counted (hereinafter referred to as the first count number) and the number of pulses of the horizontal synchronization signal HS to be counted from the start of turning off to the end of turning off (hereinafter referred to as the second count number). Is called count number).
　カウンタ７５ａ～７５ｈは、垂直同期信号ＶＳの入力をトリガとして、水平同期信号ＨＳのパルス数をカウントする。カウンタ７５ａ～７５ｈは、垂直同期信号ＶＳが入力されてから第１カウント数を数え終わった場合、パルス発生回路７６ａ～７６ｈに第１信号を出力する。またカウンタ７５ａ～７５ｈは、第１カウント数を数え終わってから第２カウント数を数え終わった場合、パルス発生回路７６ａ～７６ｈに第２信号を出力する。 The counters 75a to 75h count the number of pulses of the horizontal synchronization signal HS using the input of the vertical synchronization signal VS as a trigger. The counters 75a to 75h output the first signal to the pulse generation circuits 76a to 76h when the first count is finished after the vertical synchronization signal VS is input. The counters 75a to 75h output the second signal to the pulse generation circuits 76a to 76h when the second count number is counted after the first count number is counted.
　パルス発生回路７６ａ～７６ｈは、カウンタ７５ａ～７５ｈから第１信号が入力された場合に、Ｌｏｗレベルの信号をＬＥＤドライバ７７ａ～７７ｈに出力する。ＬＥＤドライバ７７ａ～７７ｈは、Ｌｏｗレベルの信号が入力された時点からオフ状態となり、電流が遮断され、光源ユニット５ａ～５ｈが消灯する。 The pulse generation circuits 76a to 76h output low level signals to the LED drivers 77a to 77h when the first signal is input from the counters 75a to 75h. The LED drivers 77a to 77h are turned off from when the low level signal is inputted, the current is cut off, and the light source units 5a to 5h are turned off.
　一方パルス発生回路７６ａ～７６ｈは、カウンタ７５ａ～７５ｈから第２信号が入力された場合に、Ｈｉｇｈレベルの信号をＬＥＤドライバ７７ａ～７７ｈに出力する。ＬＥＤドライバ７７ａ～７７ｈは、Ｈｉｇｈレベルの信号が入力された時点からオン状態となり、ＬＥＤドライバ７７ａ～７７ｈの定電流回路に設定された電流が光源ユニット５ａ～５ｈに流れて、光源ユニット５ａ～５ｈが点灯する。 On the other hand, when the second signal is input from the counters 75a to 75h, the pulse generation circuits 76a to 76h output high level signals to the LED drivers 77a to 77h. The LED drivers 77a to 77h are turned on when a high level signal is input, and the current set in the constant current circuits of the LED drivers 77a to 77h flows to the light source units 5a to 5h, and the light source units 5a to 5h. Lights up.
　図８は垂直同期信号ＶＳとＬＥＤドライバ７７ａ～７７ｈとの関係を示すタイミングチャートである。図８Ａは垂直同期信号ＶＳのパルス波を示しており、図８Ａにて示されたＶはパルス波の周期を表している。図８ＢはＬＥＤドライバ７７ａ～７７ｈのオン状態及びオフ状態を示しており、図８Ｂにて示されたＨはオン状態を表し、Ｌはオフ状態を表している。また図８Ｂにおける波形の高さは、電源８０から光源ユニット５ａ～５ｈに供給される電流の大きさを示している。なお図８Ｂには一例として、ＬＥＤドライバ７７ａ、７７ｂ、７７ｃ、７７ｈのオン状態又はオフ状態が示されている。 FIG. 8 is a timing chart showing the relationship between the vertical synchronization signal VS and the LED drivers 77a to 77h. FIG. 8A shows a pulse wave of the vertical synchronization signal VS, and V shown in FIG. 8A represents a cycle of the pulse wave. FIG. 8B shows an on state and an off state of the LED drivers 77a to 77h. H shown in FIG. 8B represents an on state, and L represents an off state. The height of the waveform in FIG. 8B indicates the magnitude of the current supplied from the power supply 80 to the light source units 5a to 5h. FIG. 8B shows, as an example, an on state or an off state of the LED drivers 77a, 77b, 77c, and 77h.
　図８Ｂにおいて、７７ａ、７７ｈのオン状態及びオフ状態を示す波形２００は、液晶表示パネル１に表示される画像が遷移する場合において、遷移前後の応答時間が早いときの波形を示している。破線１５０は、応答時間が中程度の場合におけるオン状態のタイミング及びオフ状態のタイミングを示しており、応答時間が早い場合には、応答時間が中程度の場合に比べて、光源ユニット５ａ、５ｈが消灯を開始する時点が所定時間早くなり、消灯後、光源ユニット５ａ、５ｈが点灯する時点も同じ時間だけ早くなる。なおＰａは波形２００におけるオフ状態の時間を示し、Ｐｂは波形２００におけるオン状態の時間を示しており、この例ではＰａ及びＰｂは略同じ時間を示している。またＥ１は波形２００にて示すタイミングで光源ユニット５ａ、５ｈを駆動する場合の駆動電流の大きさを示している。また画像の遷移時間と液晶素子の遷移時間とは対応する。 8B, a waveform 200 indicating the on state and the off state of 77a and 77h indicates a waveform when the response time before and after the transition is early when the image displayed on the liquid crystal display panel 1 transitions. A broken line 150 indicates the on-state timing and the off-state timing when the response time is medium. When the response time is early, the light source units 5a and 5h are compared to when the response time is medium. The point in time when the light source starts to turn off is a predetermined time earlier, and the point in time when the light source units 5a and 5h are turned on after the light is turned off is also advanced by the same time. Note that Pa indicates the off-state time in the waveform 200, and Pb indicates the on-state time in the waveform 200. In this example, Pa and Pb indicate substantially the same time. E1 indicates the magnitude of the drive current when the light source units 5a and 5h are driven at the timing indicated by the waveform 200. The transition time of the image corresponds to the transition time of the liquid crystal element.
　図８Ｂにおいて、７７ｂ、７７ｃのオン状態及びオフ状態を示す波形２０１は、液晶表示パネル１に表示される画像が遷移する場合において、遷移前後の応答時間が遅いときの波形を示している。なおＱａは波形２０１におけるオフ状態の時間を示し、Ｑｂは波形２０１におけるオン状態の時間を示しており、ＱａはＱｂよりも長くなっている。すなわち遷移前後の応答時間が遅い場合、光源ユニット５ｂ、５ｃの消灯時間は点灯時間よりも長くなる。 8B, a waveform 201 indicating the ON state and the OFF state of 77b and 77c indicates a waveform when the response time before and after the transition is slow when the image displayed on the liquid crystal display panel 1 transitions. Note that Qa represents the off-state time in the waveform 201, Qb represents the on-state time in the waveform 201, and Qa is longer than Qb. That is, when the response time before and after the transition is slow, the turn-off time of the light source units 5b and 5c is longer than the turn-on time.
　またＥ２は波形２０１にて示すタイミングで光源ユニット５ｂ、５ｃを駆動する場合の駆動電流の大きさを示しており、Ｅ１よりも大きい。点灯時における光源ユニット５ｂ、５ｃの輝度は、通常、消灯時間が長くなるに従って暗くなるが、駆動電流Ｅ２がＥ１よりも大きいため、光源ユニット５ｂ、５ｃに対応する第２部分１ｂ及び第３部分１ｃの輝度は、光源ユニット５ａ、５ｈに対応する第１部分１ａ及び第８部分１ｈの輝度と比べて低下せず、液晶表示パネル１全体の輝度の均一化を図ることができる。 E2 indicates the magnitude of the drive current when the light source units 5b and 5c are driven at the timing indicated by the waveform 201, and is larger than E1. The brightness of the light source units 5b and 5c at the time of lighting is normally darker as the turn-off time becomes longer. However, since the drive current E2 is larger than E1, the second part 1b and the third part corresponding to the light source units 5b and 5c. The luminance of 1c does not decrease compared to the luminance of the first portion 1a and the eighth portion 1h corresponding to the light source units 5a and 5h, and the luminance of the entire liquid crystal display panel 1 can be made uniform.
　図９Ａは、液晶表示パネル１に表示される画像が遷移する場合において、遷移後の画像の階調が高く、遷移前後の応答時間が早い場合における液晶表示パネル１の応答特性を示す模式図である。３００は応答特性を示す特性曲線である。図９Ｂは、液晶表示パネルに表示される画像が遷移する場合において、遷移後の画像の階調が低く、遷移前後の応答時間が早い場合における液晶表示パネルの応答特性を示す模式図である。３０１は応答特性を示す特性曲線である。横軸は、液晶表示パネル１に画像が保持される保持時間を示す軸であり、縦軸は階調を示す軸である。図９Ａ及び図９Ｂに、波形２００を示してある。 FIG. 9A is a schematic diagram illustrating the response characteristics of the liquid crystal display panel 1 when the image displayed on the liquid crystal display panel 1 transitions and the gradation of the image after the transition is high and the response time before and after the transition is fast. is there. Reference numeral 300 denotes a characteristic curve indicating response characteristics. FIG. 9B is a schematic diagram showing the response characteristics of the liquid crystal display panel when the image displayed on the liquid crystal display panel transitions and the gradation of the image after the transition is low and the response time before and after the transition is fast. Reference numeral 301 denotes a characteristic curve indicating response characteristics. The horizontal axis is an axis indicating the holding time for which the image is held in the liquid crystal display panel 1, and the vertical axis is an axis indicating the gradation. A waveform 200 is shown in FIGS. 9A and 9B.
　図９Ａ及び図９Ｂに示すように、遷移前後の応答時間が早い場合、特性曲線３００、３０１は現在階調から目標階調に向けて急激に上昇又は下降しており、目標階調に短時間で到達する。前述の図８Ｂにて示したように、遷移前後の応答時間が早い場合には、光源ユニット５ａ～５ｈが消灯を開始する時点が所定時間早くなる。そのため波形２００にて示すように、第１部分１ａ～第８部分１ｈにて現在階調から目標階調に向けて階調の変化が開始した直後に、光源ユニット５ａ～５ｈは消灯し、目標階調に到達した後に点灯する。このため第１部分１ａ～第８部分１ｈにて画像が遷移している間、ユーザは画像を視認することはなく、疑似輪郭の発生を防止することができる。 As shown in FIGS. 9A and 9B, when the response time before and after the transition is fast, the characteristic curves 300 and 301 are rapidly increased or decreased from the current gradation toward the target gradation, and the target gradation is short-time. To reach. As shown in FIG. 8B described above, when the response time before and after the transition is early, the time point when the light source units 5a to 5h start to turn off is advanced by a predetermined time. For this reason, as indicated by the waveform 200, immediately after the change in gradation from the current gradation toward the target gradation is started in the first part 1a to the eighth part 1h, the light source units 5a to 5h are turned off and the target is turned off. Lights after the gradation is reached. For this reason, the user does not visually recognize the image while the image transitions in the first part 1a to the eighth part 1h, and can prevent the occurrence of a pseudo contour.
　図１０Ａは、液晶表示パネルに表示される画像が遷移する場合において、遷移後の画像の階調が高く、遷移前後の応答時間が遅い場合における液晶表示パネルの応答特性を示す模式図である。３０２は応答特性を示す特性曲線である。図１０Ｂは、液晶表示パネルに表示される画像が遷移する場合において、遷移後の画像の階調が低く、遷移前後の応答時間が遅い場合における液晶表示パネルの応答特性を示す模式図である。３０３は応答特性を示す特性曲線である。横軸は、液晶表示パネル１に画像が保持される保持時間を示す軸であり、縦軸は階調を示す軸である。また図１０Ａ及び図１０Ｂに、波形２０１を示してある。 FIG. 10A is a schematic diagram showing the response characteristics of the liquid crystal display panel when the image displayed on the liquid crystal display panel transitions and the gradation of the image after the transition is high and the response time before and after the transition is slow. Reference numeral 302 denotes a characteristic curve indicating response characteristics. FIG. 10B is a schematic diagram showing the response characteristics of the liquid crystal display panel when the image displayed on the liquid crystal display panel transitions and the gradation of the image after the transition is low and the response time before and after the transition is slow. Reference numeral 303 denotes a characteristic curve indicating response characteristics. The horizontal axis is an axis indicating the holding time for which the image is held in the liquid crystal display panel 1, and the vertical axis is an axis indicating the gradation. Also, a waveform 201 is shown in FIGS. 10A and 10B.
　図１０Ａ及び図１０Ｂに示すように、遷移前後の応答時間が遅い場合、特性曲線３０２、３０３は現在階調から目標階調に向けて緩やかに上昇又は下降しており、目標階調に到達するまで長時間を要する。前述の図８Ｂにて示したように、遷移前後の応答時間が遅い場合には、光源ユニット５ａ～５ｈの消灯時間Ｑａは、点灯時間Ｑｂよりも長くなる。そのため波形２０１にて示すように、第１部分１ａ～第８部分１ｈにて現在階調から目標階調に向けて階調の変化が開始した直後に、光源ユニット５ａ～５ｈは消灯し、消灯時間Ｑａが経過した後に点灯する。このため第１部分１ａ～第８部分１ｈにて画像の遷移が略終了するまで、ユーザは画像を視認することはなく、疑似輪郭の発生を抑制することができる。 As shown in FIGS. 10A and 10B, when the response time before and after the transition is slow, the characteristic curves 302 and 303 gradually increase or decrease from the current gradation toward the target gradation and reach the target gradation. Takes a long time. As shown in FIG. 8B, when the response time before and after the transition is slow, the turn-off time Qa of the light source units 5a to 5h is longer than the turn-on time Qb. Therefore, as indicated by the waveform 201, the light source units 5a to 5h are turned off and turned off immediately after the change in gradation from the current gradation to the target gradation starts in the first part 1a to the eighth part 1h. Lights after time Qa has elapsed. For this reason, the user does not visually recognize the image until the transition of the image is almost completed in the first part 1a to the eighth part 1h, and the generation of the pseudo contour can be suppressed.
　実施の形態に係る液晶表示装置にあっては、光源ユニット５ａ～５ｈに対向する第１部分１ａ～第８部分１ｈにおいて、順次的に表示される一の画像と他の画像との階調変化に対応した応答時間を算出する。そして、算出した応答時間に基づいて前記光源ユニット５ａ～５ｈの消灯開始時点及び消灯時間を設定し、第１部分１ａ～第８部分１ｈにて液晶素子の配列状態が変化している間は、前記光源ユニット５ａ～５ｈを消灯させるので、液晶表示パネル１の応答時間が部分毎に異なる場合でも、疑似輪郭の発生を防止し、表示品位の向上を図ることができる。 In the liquid crystal display device according to the embodiment, in the first portion 1a to the eighth portion 1h facing the light source units 5a to 5h, the gradation change between one image displayed sequentially and another image The response time corresponding to is calculated. Then, based on the calculated response time, the light source units 5a to 5h are set to the start time of turning off and the turn-off time. While the arrangement state of the liquid crystal elements is changed in the first portion 1a to the eighth portion 1h, Since the light source units 5a to 5h are turned off, even when the response time of the liquid crystal display panel 1 varies from part to part, generation of pseudo contours can be prevented and display quality can be improved.
　また階調変化に基づいて応答時間を算出し、算出した応答時間に対応させて消灯時間を決定し、決定した消灯時間に対応させて、前記光源ユニット５ａ～５ｈの駆動電流を制御し、液晶表示パネル１全体での輝度の均一化を促進することができる。 In addition, a response time is calculated based on the gradation change, a turn-off time is determined according to the calculated response time, a drive current of the light source units 5a to 5h is controlled according to the determined turn-off time, and the liquid crystal Uniform brightness can be promoted throughout the display panel 1.
　また第１部分１ａ～第８部分１ｈそれぞれにおいて、設定された消灯時間が長い場合、点灯時における駆動電流を増加させて光源ユニットの輝度を大きくし、設定された消灯時間が短い場合、点灯時における駆動電流を減少させて光源ユニットの輝度を小さくして、液晶表示パネル１に一つの画像が保持されている間の輝度を均一化する。 Further, in each of the first part 1a to the eighth part 1h, when the set turn-off time is long, the drive current during lighting is increased to increase the luminance of the light source unit, and when the set turn-off time is short, The luminance of the light source unit is reduced by reducing the driving current at, so that the luminance is uniform while one image is held on the liquid crystal display panel 1.
　また第１部分１ａ～第８部分１ｈにて表示される第１部分画像及び第２部分画像それぞれの階調を求め、求めた各階調変化に応じた応答時間に基づいて、前記光源ユニット５ａ～５ｈの消灯開始時点及び消灯時間を設定し、液晶表示パネル１全体の輝度を均一化する。 Also, the gradations of the first partial image and the second partial image displayed in the first part 1a to the eighth part 1h are obtained, and the light source units 5a to 5a are obtained based on the response times corresponding to the obtained gradation changes. The lighting start time and the lighting time for 5 h are set, and the luminance of the entire liquid crystal display panel 1 is made uniform.
　また第１部分１ａ～第８部分１ｈにて表示される第１部分画像及び第２部分画像の階調変化を、対応する画像領域毎に求め、求めた各階調変化の内、所定の大きさの階調変化を抽出する。例えば階調変化の大小が応答時間の長短に対応する場合、最大の階調変化を抽出し、抽出した階調変化に対応する応答時間（最長の応答時間）に基づいて、前記光源ユニット５ａ～５ｈの消灯開始時点及び消灯時間を設定し、第１部分１ａ～第８部分１ｈにて液晶素子の応答が終了するまで、光源ユニット５ａ～５ｈを消灯させる。なお抽出する階調変化は、応答時間が最長となる階調変化であればよい。 Further, the gradation change of the first partial image and the second partial image displayed in the first part 1a to the eighth part 1h is obtained for each corresponding image area, and a predetermined magnitude is obtained from the obtained gradation changes. The gradation change is extracted. For example, when the magnitude of the gradation change corresponds to the length of the response time, the maximum gradation change is extracted, and based on the response time (longest response time) corresponding to the extracted gradation change, the light source units 5a˜5 A light-off start point and a light-off time are set for 5h, and the light source units 5a to 5h are turned off until the response of the liquid crystal element is completed in the first part 1a to the eighth part 1h. Note that the gradation change to be extracted may be a gradation change with the longest response time.
　以上説明した実施の形態は本発明の例示であり、本発明は特許請求の範囲の記載に基づいて定められる範囲内において種々変更した形態で実施することができる。 The embodiment described above is an exemplification of the present invention, and the present invention can be implemented in variously modified forms within the scope determined based on the description of the claims.
　１　液晶表示パネル
　１ａ～１ｈ　第１部分～第８部分
　５ａ～５ｈ　光源ユニット（光源）
　１０　映像処理部
　２０　倍速処理部
　３０　ＯＳ処理部
　４０　映像解析処理部
　５０　液晶表示パネルタイミング生成部
　７０　バックライト制御部
　７１　光源駆動回路 DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel 1a-1h 1st part-8th part 5a-5h Light source unit (light source)
DESCRIPTION OF SYMBOLS 10 Image | video process part 20 Double speed process part 30 OS process part 40 Image | video analysis process part 50 Liquid crystal display panel timing generation part 70 Backlight control part 71 Light source drive circuit

Claims (5)

  1. 　順次的に入力される画像を表示する液晶表示パネルと、該液晶表示パネルに対向して並設されており、前記液晶表示パネルに向けて光を出射する複数の光源とを備え、入力された画像が前記液晶表示パネルに表示される表示期間に前記複数の光源は間欠的に点灯する液晶表示装置において、
    　前記液晶表示パネルにおける各光源との対向部分それぞれに表示される一の画像における第１部分画像及び次順の画像における第２部分画像の階調変化に基づいて、応答時間を算出する応答時間算出手段と、
    　該応答時間算出手段にて算出された応答時間に基づいて、前記表示期間における前記光源の消灯期間を設定する消灯期間設定手段と
    　を備えることを特徴とする液晶表示装置。     A liquid crystal display panel that displays images that are sequentially input, and a plurality of light sources that are arranged in parallel to face the liquid crystal display panel and emit light toward the liquid crystal display panel. In the liquid crystal display device in which the plurality of light sources are intermittently lit during a display period in which an image is displayed on the liquid crystal display panel.
    Response time calculation for calculating a response time based on the gradation change of the first partial image in one image and the second partial image in the next image displayed on each of the liquid crystal display panels facing each light source. Means,
    A liquid crystal display device comprising: an extinguishing period setting unit that sets an extinguishing period of the light source in the display period based on the response time calculated by the response time calculating unit.
  2. 　前記応答時間算出手段は、前記両部分画像の階調変化を算出するようにしてあることを特徴とする請求項１に記載の液晶表示装置。 2. The liquid crystal display device according to claim 1, wherein the response time calculation means calculates a change in gradation of the partial images.
  3. 　前記応答時間算出手段は、
    　前記第１部分画像を構成する複数の画像領域それぞれと前記第１部分画像を構成する複数の画像領域に対応し、前記第２部分画像を構成する複数の画像領域それぞれとの階調変化を対応する画像領域毎に求める手段と、
    　該手段にて求めた複数の階調変化に基づいて応答時間の最大値を抽出する手段と
    　を備えることを特徴とする請求項１に記載の液晶表示装置。     The response time calculation means includes
    Corresponding to each of a plurality of image areas constituting the first partial image and a plurality of image areas constituting the first partial image, and corresponding to a gradation change of each of the plurality of image areas constituting the second partial image Means for each image area to be
    The liquid crystal display device according to claim 1, further comprising: means for extracting a maximum response time value based on a plurality of gradation changes obtained by the means.
  4. 　前記応答時間算出手段にて算出された応答時間に基づいて、前記対向部分に対向する前記光源の駆動電流を制御する電流値制御手段を備えること
    　を特徴とする請求項１から３のいずれか一つに記載の液晶表示装置。     4. The apparatus according to claim 1, further comprising a current value control unit configured to control a driving current of the light source facing the facing portion based on the response time calculated by the response time calculating unit. Liquid crystal display device described in 1.
  5. 　前記電流値制御手段は、前記消灯期間設定手段によって設定された前記消灯期間の長短に応じて、駆動電流を増減させるようにしてあること
    　を特徴とする請求項４に記載の液晶表示装置。     5. The liquid crystal display device according to claim 4, wherein the current value control unit is configured to increase or decrease a drive current according to the length of the extinguishing period set by the extinguishing period setting unit.
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