WO2019031479A1 - Display device - Google Patents

Display device Download PDF

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Publication number
WO2019031479A1
WO2019031479A1 PCT/JP2018/029536 JP2018029536W WO2019031479A1 WO 2019031479 A1 WO2019031479 A1 WO 2019031479A1 JP 2018029536 W JP2018029536 W JP 2018029536W WO 2019031479 A1 WO2019031479 A1 WO 2019031479A1
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WO
WIPO (PCT)
Prior art keywords
display
light
light sources
lighting
display device
Prior art date
Application number
PCT/JP2018/029536
Other languages
French (fr)
Japanese (ja)
Inventor
正史 屋鋪
Original Assignee
シャープ株式会社
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Filing date
Publication date
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Publication of WO2019031479A1 publication Critical patent/WO2019031479A1/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
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • 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
    • 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
    • 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

Definitions

  • the present invention relates to a display device, and more particularly to a display device that displays an image by a field sequential method.
  • a display device that displays a color image without using a color filter a display device that displays a color image by a field sequential method is known.
  • Japanese Patent Application Laid-Open No. 2003-60944 discloses such a field-sequential liquid crystal display device.
  • a color image is displayed by sequentially turning on three color light sources of RGB sequentially in synchronization with the display of each image data of red (R), green (G) and blue (B). .
  • the lighting states of the light sources of three colors are controlled to perform white balance adjustment, and a color image is displayed based on the white balance adjustment result.
  • white balance adjustment when there is a difference in the lighting time of the three color light sources, a predetermined constant current for lighting control is input to the light sources for each light source at the start of lighting for color image display The timing of transition to the state varies. This is because the timing of transition from the transient state to the steady state varies when the constant current source is activated. As a result, the color balance of the three colors at the start of lighting may be lost, and an unintended color may be displayed.
  • An object of the present invention is to provide a technique for preventing display in an unintended color at the start of lighting for color image display in a field sequential display device.
  • the display device includes a plurality of light sources emitting light in different colors, and displays an image according to a field sequential method in which each of the plurality of light sources is sequentially lit in each subfield obtained by dividing one frame.
  • a light emission control unit that controls lighting of each of the plurality of light sources based on an input video signal, and the light emission control unit is configured to display a color image from the extinguished state of the plurality of light sources
  • the plurality of light sources are turned on such that the lighting time is equal for each of the subfields in the predetermined period until the lighting start for lighting, and after the predetermined period has elapsed, the result of the white balance adjustment made in advance
  • the lighting time of the plurality of light sources is controlled in accordance with.
  • display in an unintended display color can be prevented at the start of lighting for displaying a color image.
  • FIG. 1 is a schematic view showing a schematic configuration of a liquid crystal display device in the embodiment.
  • FIG. 2A is a cross-sectional view of a plane perpendicular to the display surface of the display shown in FIG.
  • FIG. 2B is a cross-sectional view of a surface perpendicular to the display surface of the display shown in FIG.
  • FIG. 3 is a functional block diagram showing a configuration example of the image processing unit shown in FIG.
  • FIG. 4 is an example of a pulse signal waveform used for lighting control of the light source shown in FIG.
  • FIG. 5 is an example of the pulse signal waveform used for lighting control of the light source which concerns on a modification.
  • the display device includes a plurality of light sources emitting light in different colors, and displays an image according to a field sequential method in which each of the plurality of light sources is sequentially lit in each subfield obtained by dividing one frame.
  • a light emission control unit that controls lighting of each of the plurality of light sources based on an input video signal, and the light emission control unit is configured to display a color image from the extinguished state of the plurality of light sources
  • the plurality of light sources are turned on such that the lighting time is equal for each of the subfields in the predetermined period until the lighting start for lighting, and after the predetermined period has elapsed, the result of the white balance adjustment made in advance
  • the lighting time of the plurality of light sources is controlled according to (first configuration).
  • the lighting time of all the light sources is made equal in each subfield in a predetermined period from the extinguished state of the plurality of light sources to the lighting start for color image display, and all the light sources are lit. Therefore, at the start of lighting at the time of color image display, the timing of transition to a steady state where a predetermined constant current is input is unlikely to vary for each light source, and display in an unintended color can be prevented.
  • the display control unit further includes: a display panel having a plurality of pixels; and a display control unit configured to control the transmittance of the pixels in the display panel based on the video signal.
  • the transmittance of the pixel may be controlled so as to display black during a period (second configuration). According to the second configuration, by displaying in black during a predetermined period before the start of lighting for displaying a color image, it is possible to further prevent display in an unintended color when displaying a color image.
  • the lighting time of the plurality of light sources in the predetermined period may be longer than the lighting time of the plurality of light sources after the lapse of the predetermined period (third configuration).
  • the lighting time of each light source in a predetermined period before lighting start for color image display is shorter than the lighting time of each light source after the predetermined time period, each light source in a short time Can be transitioned to a steady state in which a predetermined constant current is input.
  • the plurality of light sources include light sources that emit light in respective colors of red (R), green (G), and blue (B), and one frame is divided.
  • the sub-fields may be four sub-fields in which image data corresponding to each color of white (W), red (R), green (G) and blue (B) are sequentially displayed (fourth configuration) .
  • the plurality of light sources include light sources that emit light in respective colors of red (R), green (G), and blue (B), and one frame is divided.
  • the sub-frame may be three subfields in which image data corresponding to each color of red (R), green (G) and blue (B) are sequentially displayed (fifth configuration).
  • FIG. 1 is a schematic view showing a schematic configuration of a display device 1 in the present embodiment.
  • the display device 1 is a liquid crystal display device that displays a color image by a field sequential method.
  • a color image is displayed by displaying screens of different colors for each of a plurality of sub-fields that can be created by dividing a display period of one screen, that is, one frame period.
  • the display device 1 includes a display panel 11, a gate driver 12, a source driver 13, a display control circuit 14, a backlight 15, a backlight control circuit 16, and an image processing unit 17.
  • the display panel 11 is a display panel using liquid crystal, and a plurality of pixels formed by a plurality of gate lines 110 and a plurality of source lines 111 are formed in a matrix.
  • the pixel includes a thin film transistor (TFT) 113 connected to the gate line 110 and the source line 111, and a pixel electrode 114 connected to the TFT 113.
  • TFT thin film transistor
  • the gate line 110 is connected to the gate driver 12, and the source line 111 is connected to the source driver 13.
  • the gate driver 12 and the source driver 13 are connected to the display control circuit 14.
  • the gate driver 12 sequentially scans the gate lines 110 based on control signals such as timing signals and clock signals from the display control circuit 14.
  • the source driver 13 applies a voltage corresponding to the image signal to each source line 111 based on the timing signal and the image signal from the display control circuit 14.
  • the TFT 113 connected to the gate line 110 is turned on, a voltage supplied to the source line 111 is applied to the pixel electrode 114, and the alignment of liquid crystal molecules in the pixel is controlled.
  • the backlight 15 includes a light source 150 and a light guide plate 151.
  • the light source 150 includes LEDs (Light Emitting Diodes) 15R, 15G, and 15B that emit light of each color of red (R), green (G), and blue (B).
  • LEDs Light Emitting Diodes
  • the light guide plate 151 is provided on the back side of the display panel 1.
  • the light guide plate 151 is formed of a transparent material.
  • a portion of the backlight 15 overlapping the display screen of the display panel 11, that is, the display area where the pixels are arranged is transparent.
  • the light source 150 is disposed at a position facing one side surface of the light guide plate 151 in FIG. 1, the light source 150 may be disposed at a position facing a plurality of side surfaces of the light guide plate 151.
  • FIG. 2A and 2B are cross-sectional views of a plane perpendicular to the display surface of the display device 1.
  • FIG. 2A shows an example of a state in which the backlight 15 is turned off to display a transmitted light image including a transmission area seen behind the display device 1.
  • FIG. 2B shows an example of a state in which the backlight 15 is turned on to display a color image.
  • the display panel 11 is provided at a position where the backlight 15 overlaps with the display screen in a direction perpendicular to the display screen.
  • the display panel 11 includes two first and second substrates 25 and 22 and a liquid crystal 24 provided therebetween.
  • the gate line 110, the source line 111, the switching element 113, the pixel electrode 114, and the like are provided on one surface of the first substrate 25 (for example, the surface opposite to the backlight 15).
  • a polarizing plate 26 is provided on the other surface of the first substrate 25.
  • a common electrode (not shown) is formed on one surface of the second substrate 22 (for example, the surface on the backlight 15 side).
  • a polarizing plate 21 is provided on the other surface of the second substrate 22.
  • the first substrate 25 and the second substrate 22 can be formed of, for example, glass or resin.
  • the light guide plate 151 of the backlight 15 has an incident surface 15a of the light from the light source 150, and an emission surface 15b for emitting the light of the light source 150 that has entered from the incident surface 15a.
  • the display panel 11 is provided so as to overlap the emission surface 15 b of the light guide plate 151. That is, the backlight 15 is an illumination unit that emits light to one surface of the display panel 11.
  • the back surface 15c which is a surface facing the exit surface 15b of the light guide plate 151
  • light can be transmitted through the display area where the image of the display panel 11 is displayed, ie, the area overlapping the display screen.
  • the backlight 15 is configured such that light can be transmitted through a portion overlapping the display screen of the display panel 11.
  • a member provided at a position overlapping the display area of the display panel 11 in the direction perpendicular to the display screen is formed of a transparent material.
  • a light guide plate 151 capable of transmitting light in the direction perpendicular to the display screen is disposed. That is, a member that shields light is not disposed on the back surface of the display panel 11.
  • a transparent material such as an acrylic plate may be used as a member on the back side of the light guide plate 151, or nothing may be arranged on the back side of the light guide plate 151.
  • the light guide plate 151 is configured such that the light from the light source 150 propagating through the light guide plate 151 can be easily emitted toward the display panel 11 from the emission surface 15 b facing the display panel 11.
  • dots that reflect incident light can be formed at predetermined intervals on the emission surface 15 b and the back surface 15 c of the light guide plate 151.
  • the light of the light source 150 that has entered from the incident surface 15 a of the light guide plate 151 travels while being totally reflected in the light guide plate 151.
  • the light from the light source 150 that has entered the dots on the back surface 15 c of the light guide plate 151 is reflected by the dots and emitted from the emission surface 15 b of the light guide plate 151 toward the display panel 11.
  • the dots are formed, for example, by printing of a white opaque ink (organic UV curable ink or the like) or a metal ink (aluminum or gold or the like).
  • the surface of the light guide plate 151 can be processed into a shape that allows light to be easily reflected by die pressing or laser processing instead of dots by printing.
  • the light guide plate 151 may be formed of a material that easily reflects light without being limited to a form that utilizes reflection by the shape of the surface of the light guide plate 151.
  • the light guide plate 151 can include a reflection structure that reflects light traveling inside and emits the light to the outside.
  • the backlight 15 when the backlight 15 is lit, the amount of light emitted from the light source 150 through the light guide plate 151 to the display panel 11 passes through the back surface 15 c of the light guide plate 151 and reaches the display panel 11 Compared to Therefore, when the backlight 15 is lit, the color by the light of the backlight 15 is displayed on the display panel 11, and the rear of the display device 1 is not seen through.
  • the display device 1 has a color display mode and a transmitted light image display mode.
  • the backlight 15 is turned on, and the display panel 11 displays a color image that does not include a transmissive area that can be seen behind the display device 1.
  • the transmitted light image display mode the backlight 15 is turned off, and the display panel 11 displays a monotone image (transmitted light image) including the transmitted area.
  • the display panel 11 displays an image by controlling the transmittance of light incident on the display panel 11 for each pixel based on the signal of the panel drive unit in any of the color display mode and the transmitted light image display mode.
  • the display panel 11 In the case of the color display mode, that is, when the backlight 15 is turned on when displaying an image, the display panel 11 transmits the light from the light source 150 propagating in the light guide plate 151 and entering the display panel 11 through the emission surface 15 b. Will control the rate.
  • the transmitted light image display mode that is, when the backlight 15 is turned off when displaying an image, the display panel 11 penetrates the back surface 15 c of the light guide plate 151 from the outside of the display device 1 and enters the display panel 11. Control the light transmission rate. Thereby, a transmitted light image including the transmission area can be displayed. In the transmissive region, the rear of the display device 1 can be seen through.
  • the LEDs 15 ⁇ / b> R, 15 ⁇ / b> G, and 15 ⁇ / b> B are disposed, for example, at positions facing one side surface of the light guide plate 151.
  • the LEDs 15 R, 15 G, 15 B are connected to the backlight control circuit 16.
  • the backlight control circuit 16 includes a backlight drive circuit (not shown) that drives the LEDs 15R, 15G, and 15B. Each of the LEDs 15R, 15G, and 15B lights on the basis of a pulse signal indicating a lighting time input from the corresponding backlight drive circuit.
  • the display control circuit 14 and the backlight control circuit 16 are connected to the image processing unit 17.
  • the configuration of the image processing unit 17 will be described.
  • FIG. 3 is a functional block diagram showing a configuration example of the image processing unit 17.
  • the image processing unit 17 includes a coordinate generation unit 171, a determination unit 172, a separation unit 173, an image data generation unit 174, a backlight data generation unit 175, and a timing control unit 176.
  • the image processing unit 17 receives, for example, a video signal for each frame (60 Hz).
  • the coordinate generation unit 171 can be externally rewritten to hold the total number of horizontal pixels in the extending direction of the gate lines 110 (see FIG. 1) of the display panel 11 and the total number of vertical lines in the extending direction of the source lines 111. It has a register.
  • the coordinate generation unit 171 increments the horizontal counter value by one each time a pixel value (for example, a gradation value of RGB) included in the video signal is input. When the horizontal counter value becomes equal to M, the vertical counter value is incremented by one at the input of the next pixel value, and the horizontal counter value is returned to 1.
  • the coordinate generation unit 171 sets the upper left pixel in the image represented by the video signal as the origin (0, 0), the horizontal direction as the X direction, and the vertical direction as the Y direction, and coordinates (x, y) of the input pixel value.
  • the determination unit 172 determines whether the pixel value included in the input video signal is a pixel value of a predetermined coordinate, and outputs the determination result to the separation unit 173. In the present embodiment, the determination unit 172 determines whether the coordinates (x, y) of the pixel value included in the input video signal are, for example, (0, 0). That is, the determination unit 172 uses the pixel value of the coordinate (0, 0) among the pixel values included in the video signal for the on / off control of the LEDs 15R, 15G, and 15B.
  • the data included in the video signal may have a portion corresponding to the display period of the image and a portion corresponding to the blanking period.
  • data for controlling turning on / off of the LEDs 15R, 15G, and 15B can be included in a portion corresponding to the blanking period.
  • One frame period is divided into an image display period and a blanking period.
  • the pixel value of one frame period has a portion corresponding to the image display period and a portion for the blanking period.
  • the portion corresponding to the image display period includes data such as the gradation value of each pixel corresponding to each TFT 113.
  • the portion corresponding to the blanking period includes control data indicating whether to turn on the LEDs 15R, 15G, and 15B in the frame period.
  • the determination unit 172 outputs, as a determination result, to the separation unit 173, information indicating whether the pixel value of each coordinate is the gradation value of the image to be displayed or the control data representing the on / off of the LED. .
  • the separating unit 173 separates the image data indicating the image to be displayed and the control data of the LED from each pixel value of the input video signal according to the determination result of the determining unit 172.
  • the image data is output to the image data generation unit 174, and the control data of the LED is output to the backlight data generation unit 175.
  • the image data generation unit 174 generates subfield image data to be displayed in each period of a plurality of subfields formed by dividing one frame based on the input image data.
  • image display data for performing field sequential display from image data including gradation values of respective colors of RGB mixed colors W (white) are added to the respective colors of RGB to respective colors of WRGB.
  • W white
  • the generated subfield image is output to the timing control unit 176.
  • the backlight data generation unit 175 generates LED control data for causing the LEDs of the corresponding colors to emit light in the subfield period corresponding to each color of WRGB, and outputs the generated data to the timing control unit 176.
  • the backlight data generation unit 175 and the timing control unit 176 simultaneously cause the LEDs 15R, 15G, and 15B to emit light in the subfield period corresponding to W (white), and correspond to the LEDs 15R and G in the subfield period corresponding to R.
  • the LED 15B is controlled to emit light in the subfield periods corresponding to the LEDs 15G and 15B, respectively.
  • the backlight data generation unit 175 is a backlight that represents lighting / extinguishing of the LEDs 15R, 15G, and 15B for each frame based on control data that represents lighting / extinguishing of the LED when displaying an image indicated by a pixel value.
  • Generate data For example, when each of the RGB gradation values (R, G, B) included in the pixel value of the coordinates (0, 0) is larger than the threshold, the LEDs 15R, 15G, 15B are turned on in the frame period for displaying the image data. Generate backlight data.
  • the backlight data generation unit 175 determines that the gradation value included in the pixel value at the coordinate (0, 0) is (0, 0, 0). If there is, backlight data is generated that instructs the LEDs 15R, 15G, and 15B to turn off.
  • the backlight data generation unit 175 instructs the LED 15R, 15G, 15B to turn on the backlight data Generate
  • the generated backlight data is input to the image data generation unit 174 and the timing control unit 176.
  • the detection process of the control data showing ON / OFF of LED is not restricted to the said example.
  • the input pixel value includes control data indicating whether or not lighting is performed.
  • this control data may be separately input.
  • control data representing lighting / extinguishing may be input simultaneously with the pixel value or in association with the pixel value.
  • the image processing unit 17 inputs the control data to the backlight data generation unit 175 or the timing control unit 176 in synchronization with the pixel value of one frame period or in association with the pixel value of one frame period. .
  • the timing control unit 176 performs timing control for synchronizing the display of subfield images of WRGB with the lighting of the LEDs 15R, 15G, and 15B.
  • the timing control unit 176 controls the timing control signal 14 to synchronize the timing of irradiating each color of RGB and the mixed color W with the timing of displaying each subfield image of WRGB as shown in FIG. And the backlight control circuit 16 (see FIG. 1).
  • the display control circuit 14 displays the display panel 11 for each of the gate driver 12 and the source driver 13 based on each sub-field image of WRGB input from the timing control unit 176 and the timing control signal.
  • a control signal such as a timing signal for driving is input.
  • the backlight control circuit 16 includes an LED drive circuit (not shown) for driving each of the LEDs 15R, 15G, and 15B.
  • the backlight control circuit 16 switches the light emission colors of the LEDs 15R, 15G, and 15B in accordance with the timing when the subfield image of each color of WRGB is displayed on the display panel 11 by the display control circuit 14. That is, the backlight control circuit 16 turns on the LEDs 15R, 15G, and 15B by the LED drive circuits (not shown) corresponding to the LEDs 15R, 15G, and 15B based on the timing control signal input from the timing control unit 176. Control the light off.
  • the backlight control circuit 16 drives each of the LEDs 15R, 15G, and 15B for a certain period of time from when the LEDs 15R, 15G, and 15B are turned off to when lighting for color image display starts (shown in FIG. An adjustment process is performed to bring the output signal into a steady state in which a predetermined constant current is output. Then, after the adjustment processing, each LED drive circuit controls the lighting time of the LEDs 15R, 15G, and 15B according to the result of the white balance adjustment made in advance, and starts lighting for color image display. Each lighting time of LED15R, 15G, 15B is controlled by the pulse signal by which the pulse width was adjusted by the PWM (Pulse Width Modulation) modulation system.
  • PWM Pulse Width Modulation
  • FIG. 4 is an example of waveforms of pulse signals output to the LEDs 15R, 15G, and 15B.
  • a period T1 of the first frame to N-1 (N: an integer of 3 or more) frame indicates the lighting state of the LEDs 15R, 15G, 15B in the adjustment processing period.
  • the adjustment processing period T1 is a period of a transient state before each LED drive circuit enters a steady state.
  • a period T2 after the Nth frame indicates the lighting state of the LEDs 15R, 15G, and 15B after each LED drive circuit has transitioned to the steady state.
  • a video signal is input at 60 Hz for each frame, and one frame period is divided into four subfields F1 to F4 corresponding to WRGB.
  • the frequency of one subfield is 240 Hz, which is four times the frequency of the video signal.
  • subfield images corresponding to each color of WRGB are displayed.
  • each LED drive circuit in the adjustment processing period T1, is in a transient state, and simultaneously turns on the LEDs 15R, 15G, and 15B in all subfields F1 to F4 in each frame.
  • the pulse signals for each of the LEDs 15R, 15G, and 15B have the same pulse width.
  • the LEDs 15R, 15G, and 15B are lighted in substantially the same lighting time in each subfield period of F1 to F4.
  • the pulse widths of the respective pulse signals are adjusted.
  • the pulse width is adjusted so that the lighting time satisfies the relationship of LED15B ⁇ LED15G ⁇ LED15R.
  • the LEDs 15R, 15G, and 15B are turned on in response to pulse signals having pulse widths different from one another, and a W subfield image is displayed.
  • the subfield F2 only the LED 15R is turned on in the lighting time corresponding to the pulse signal of the LED 15R, and the R subfield image is displayed.
  • the sub-field F3 only the LED 15G lights up in the lighting time according to the pulse signal of the LED 15G, and the sub-field image of G is displayed.
  • only the LED 15B lights up in the lighting time according to the pulse signal of the LED 15B, and the sub-field image of B is displayed.
  • the lighting time of each of the LEDs 15R, 15G, and 15B in each subfield of the adjustment processing period T1 of each LED driving circuit is the lighting start time for color image display after each LED driving circuit transitions to the steady state. It makes longer than each lighting time of LED15R, 15G, and 15B in. Thereby, the time until the LED drive circuit (not shown) which drives each of LED15R, 15G, and 15B becomes a steady state which outputs a predetermined
  • each LED driving circuit that drives each of the LEDs 15R, 15G, and 15B at the start of lighting for performing color image display A variation occurs in the time until the steady state (not shown) outputs a predetermined constant current to the corresponding LED.
  • the LEDs 15R, 15G, and 15B are simultaneously lit in the same lighting time in each subfield of each frame. Therefore, at the start of lighting for performing color image display, the time when the LED drive circuits (not shown) of the LEDs 15R, 15G, and 15B (not shown) transition to the steady state does not vary, preventing image display in unintended colors can do.
  • the orientation of liquid crystal molecules in the display panel 11 is controlled by the display control circuit 14 (see FIG. 1) so that a black image is displayed on the display panel 11. It is also good. By displaying the display panel 11 in black, display in an unintended color can be further prevented.
  • a display concerning the present invention is not limited to composition of an embodiment mentioned above, and can be considered as various modification composition.
  • one frame is divided into four subfields corresponding to each color of WRGB
  • one frame may be divided into three subfields corresponding to each color of RGB.
  • one frame period is divided into three subfields F1 to F3.
  • the sub-field is 180 Hz.
  • the pulse width of the pulse signal for each of the LEDs 15R, 15G, and 15B is equal in all subfields F1 to F3 for each frame.
  • the LEDs 15R, 15G, and 15B light up in substantially the same lighting time.
  • the pulse width of each pulse signal is adjusted so as to become the lighting time of the LEDs 15R, 15G, and 15B according to the white balance adjustment after the Nth frame after each LED drive circuit transitions to the steady state.
  • the pulse width is adjusted so that the lighting time becomes longer in the order of the LEDs 15B, 15G, and 15R, as in the above-described embodiment. That is, as shown in FIG. 5, in the subfield F1 of the Nth frame, only the LED 15R lights up in the lighting time according to the white balance adjustment, and the R subfield image is displayed. Further, in the sub-field F2, only the LED 15G is turned on in the lighting time according to the white balance adjustment, and the sub-field image of G is displayed. Further, in the sub-field F3, only the LED 15B lights up in the lighting time according to the white balance adjustment, and the sub-field image of B is displayed.
  • the display device to which the present invention can be applied is not limited to the liquid crystal display device.
  • the present invention may be applied to other display devices (display devices other than liquid crystal display devices) having an illumination unit that emits light on one surface of the display panel and having a function to show through the back of the display screen.
  • the display panel includes a display panel including a plurality of shutter elements arranged two-dimensionally to transmit light, capable of controlling an off state to block light for each pixel, and a backlight, in one frame period.
  • the present invention can also be applied to a display device that switches the on state and the off state of the shutter element a plurality of times in accordance with each bit of the image data.

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Abstract

Provided is a technology of a field sequential display device in which, at the start of lighting of a light source such as a back light, display in an unintended color is prevented. The display device is provided with a plurality of light source LEDs 15R, 15G, 15B for emitting light in different colors, and performs field-sequential image display in which the light sources are sequentially lighted for each of sub-fields F1-F4 that are obtained by dividing one frame. The display device is provided with a light emission control unit that controls lighting of the light sources on the basis of an inputted image signal. In a prescribed time period T1 from the off state of the light source LEDs 15R, 15G, 15B to start of lighting for color image display, the light emission control unit lights the light source LEDs 15R, 15G, 15B such that the lighting times of the light source LEDs 15R, 15G, 15B are equal to one another for each of the sub-fields. In a time period T2 following the predetermined time period T1, the light emission control unit controls the lighting times of the light source LEDs 15R, 15G, 15B in accordance with the result of preliminary white balance adjustment.

Description

表示装置Display device
　本発明は、表示装置に関し、特にフィールドシーケンシャル方式で画像表示を行う表示装置に関する。 The present invention relates to a display device, and more particularly to a display device that displays an image by a field sequential method.
　従来より、カラーフィルタを用いることなくカラー画像を表示する表示装置として、フィールドシーケンシャル方式でカラー画像を表示する表示装置が知られている。特開２００３－６０９４４号公報には、このようなフィールドシーケンシャル方式の液晶表示装置が開示されている。フィールドシーケンシャル方式では、赤（Ｒ）、緑（Ｇ）、青（Ｂ）の各画像データの表示に同期させて、ＲＧＢの３色の光源を選択的に順次点灯させることでカラー画像を表示する。 2. Description of the Related Art Conventionally, as a display device that displays a color image without using a color filter, a display device that displays a color image by a field sequential method is known. Japanese Patent Application Laid-Open No. 2003-60944 discloses such a field-sequential liquid crystal display device. In the field sequential method, a color image is displayed by sequentially turning on three color light sources of RGB sequentially in synchronization with the display of each image data of red (R), green (G) and blue (B). .
　ところで、上記フィールドシーケンシャル方式の表示装置において、３色の光源の点灯状態を制御して、ホワイトバランス調整を行い、ホワイトバランス調整結果に基づいてカラー画像を表示する。ホワイトバランス調整の際、３色の光源の点灯時間に差があると、カラー画像表示のための点灯開始時、光源ごとに、当該光源に点灯制御のための所定の定電流が入力される定常状態に遷移するタイミングがばらつく。これは、定電流源の起動時に過渡状態から定常状態に遷移するタイミングがばらつくためである。その結果、点灯開始時の３色の色バランスが崩れ、意図しない色で表示されることがある。 By the way, in the display device of the field sequential system, the lighting states of the light sources of three colors are controlled to perform white balance adjustment, and a color image is displayed based on the white balance adjustment result. In white balance adjustment, when there is a difference in the lighting time of the three color light sources, a predetermined constant current for lighting control is input to the light sources for each light source at the start of lighting for color image display The timing of transition to the state varies. This is because the timing of transition from the transient state to the steady state varies when the constant current source is activated. As a result, the color balance of the three colors at the start of lighting may be lost, and an unintended color may be displayed.
　本発明は、フィールドシーケンシャル方式の表示装置において、カラー画像表示のための点灯開始時に意図しない色での表示を防止する技術を提供することを目的とする。 An object of the present invention is to provide a technique for preventing display in an unintended color at the start of lighting for color image display in a field sequential display device.
　本発明の一実施形態における表示装置は、互いに異なる色で発光する複数の光源を備え、１フレームを分割したサブフィールドごとに、前記複数の光源のそれぞれを順次点灯させるフィールドシーケンシャル方式で画像表示を行う表示装置であって、入力される映像信号に基づいて、前記複数の光源のそれぞれの点灯を制御する発光制御部を備え、前記発光制御部は、前記複数の光源の消灯状態からカラー画像表示のための点灯開始までの所定期間において、前記サブフィールドごとに、それぞれの点灯時間が同等となるように前記複数の光源を点灯させ、当該所定期間の経過後、予めなされたホワイトバランス調整の結果に応じて前記複数の光源の点灯時間を制御する。 The display device according to an embodiment of the present invention includes a plurality of light sources emitting light in different colors, and displays an image according to a field sequential method in which each of the plurality of light sources is sequentially lit in each subfield obtained by dividing one frame. A light emission control unit that controls lighting of each of the plurality of light sources based on an input video signal, and the light emission control unit is configured to display a color image from the extinguished state of the plurality of light sources The plurality of light sources are turned on such that the lighting time is equal for each of the subfields in the predetermined period until the lighting start for lighting, and after the predetermined period has elapsed, the result of the white balance adjustment made in advance The lighting time of the plurality of light sources is controlled in accordance with.
　本発明によれば、フィールドシーケンシャル方式の表示装置において、カラー画像表示のための点灯開始時に、意図しない表示色での表示を防止することができる。 According to the present invention, in the field sequential display device, display in an unintended display color can be prevented at the start of lighting for displaying a color image.
図１は、実施形態における液晶表示装置の概略構成を示す模式図である。FIG. 1 is a schematic view showing a schematic configuration of a liquid crystal display device in the embodiment. 図２Ａは、図１に示す表示装置の表示面に垂直な面の断面図である。FIG. 2A is a cross-sectional view of a plane perpendicular to the display surface of the display shown in FIG. 図２Ｂは、図１に示す表示装置の表示面に垂直な面の断面図である。FIG. 2B is a cross-sectional view of a surface perpendicular to the display surface of the display shown in FIG. 図３は、図１に示す画像処理部の構成例を示す機能ブロック図である。FIG. 3 is a functional block diagram showing a configuration example of the image processing unit shown in FIG. 図４は、図１に示す光源の点灯制御に用いるパルス信号波形の一例である。FIG. 4 is an example of a pulse signal waveform used for lighting control of the light source shown in FIG. 図５は、変形例に係る光源の点灯制御に用いるパルス信号波形の一例である。FIG. 5: is an example of the pulse signal waveform used for lighting control of the light source which concerns on a modification.
　本発明の一実施形態における表示装置は、互いに異なる色で発光する複数の光源を備え、１フレームを分割したサブフィールドごとに、前記複数の光源のそれぞれを順次点灯させるフィールドシーケンシャル方式で画像表示を行う表示装置であって、入力される映像信号に基づいて、前記複数の光源のそれぞれの点灯を制御する発光制御部を備え、前記発光制御部は、前記複数の光源の消灯状態からカラー画像表示のための点灯開始までの所定期間において、前記サブフィールドごとに、それぞれの点灯時間が同等となるように前記複数の光源を点灯させ、当該所定期間の経過後、予めなされたホワイトバランス調整の結果に応じて前記複数の光源の点灯時間を制御する（第１の構成）。 The display device according to an embodiment of the present invention includes a plurality of light sources emitting light in different colors, and displays an image according to a field sequential method in which each of the plurality of light sources is sequentially lit in each subfield obtained by dividing one frame. A light emission control unit that controls lighting of each of the plurality of light sources based on an input video signal, and the light emission control unit is configured to display a color image from the extinguished state of the plurality of light sources The plurality of light sources are turned on such that the lighting time is equal for each of the subfields in the predetermined period until the lighting start for lighting, and after the predetermined period has elapsed, the result of the white balance adjustment made in advance The lighting time of the plurality of light sources is controlled according to (first configuration).
　第１の構成によれば、複数の光源の消灯状態からカラー画像表示のための点灯開始までの所定期間、各サブフィールドにおいて、全ての光源の点灯時間を同等にし、全ての光源を点灯させる。そのため、カラー画像表示の際の点灯開始時に、光源ごとに、所定の定電流が入力される定常状態に遷移するタイミングがばらつきにくく、意図しない色で表示されることを防止することができる。 According to the first configuration, the lighting time of all the light sources is made equal in each subfield in a predetermined period from the extinguished state of the plurality of light sources to the lighting start for color image display, and all the light sources are lit. Therefore, at the start of lighting at the time of color image display, the timing of transition to a steady state where a predetermined constant current is input is unlikely to vary for each light source, and display in an unintended color can be prevented.
　第１の構成において、複数の画素を有する表示パネルと、前記映像信号に基づいて、前記表示パネルにおける画素の透過率を制御する表示制御部と、をさらに備え、前記表示制御部は、前記所定期間の間、黒色表示となるように前記画素の透過率を制御することとしてもよい（第２の構成）。第２の構成によれば、カラー画像表示のための点灯開始前の所定期間の間、黒色表示にすることで、カラー画像表示の際に意図しない色での表示をさらに防止できる。 In the first configuration, the display control unit further includes: a display panel having a plurality of pixels; and a display control unit configured to control the transmittance of the pixels in the display panel based on the video signal. The transmittance of the pixel may be controlled so as to display black during a period (second configuration). According to the second configuration, by displaying in black during a predetermined period before the start of lighting for displaying a color image, it is possible to further prevent display in an unintended color when displaying a color image.
　第１の構成において、前記所定期間における前記複数の光源の点灯時間は、前記所定期間の経過後の前記複数の光源の点灯時間よりも長くてもよい（第３の構成）。第３の構成によれば、カラー画像表示のための点灯開始前の所定期間における各光源の点灯時間が、所定期間経過後の各光源の点灯時間よりも短い場合と比べ、短時間で各光源を所定の定電流が入力される定常状態に遷移させることができる。 In the first configuration, the lighting time of the plurality of light sources in the predetermined period may be longer than the lighting time of the plurality of light sources after the lapse of the predetermined period (third configuration). According to the third configuration, the lighting time of each light source in a predetermined period before lighting start for color image display is shorter than the lighting time of each light source after the predetermined time period, each light source in a short time Can be transitioned to a steady state in which a predetermined constant current is input.
　第１から第３のいずれかの構成において、前記複数の光源は、赤（Ｒ）、緑（Ｇ）、青（Ｂ）のそれぞれの色で発光する光源を有し、前記１フレームを分割したサブフィールドは、白（Ｗ）、赤（Ｒ）、緑（Ｇ）、青（Ｂ）の各色に対応する画像データを順次表示させる４つのサブフィールドであることとしてもよい（第４の構成）。 In any one of the first to third configurations, the plurality of light sources include light sources that emit light in respective colors of red (R), green (G), and blue (B), and one frame is divided. The sub-fields may be four sub-fields in which image data corresponding to each color of white (W), red (R), green (G) and blue (B) are sequentially displayed (fourth configuration) .
　第１から第３のいずれかの構成において、前記複数の光源は、赤（Ｒ）、緑（Ｇ）、青（Ｂ）のそれぞれの色で発光する光源を有し、前記１フレームを分割したサブフレームは、赤（Ｒ）、緑（Ｇ）、青（Ｂ）の各色に対応する画像データを順次表示させる３つのサブフィールドであることとしてもよい（第５の構成）。 In any one of the first to third configurations, the plurality of light sources include light sources that emit light in respective colors of red (R), green (G), and blue (B), and one frame is divided. The sub-frame may be three subfields in which image data corresponding to each color of red (R), green (G) and blue (B) are sequentially displayed (fifth configuration).
　以下、図面を参照し、本発明の実施の形態を詳しく説明する。図中同一または相当部分には同一符号を付してその説明は繰り返さない。なお、説明を分かりやすくするために、以下で参照する図面においては、構成が簡略化または模式化して示されたり、一部の構成部材が省略されたりしている。また、各図に示された構成部材間の寸法比は、必ずしも実際の寸法比を示すものではない。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings have the same reference characters allotted and description thereof will not be repeated. In order to make the description easy to understand, in the drawings referred to in the following, the configuration is simplified or schematically shown, or some constituent members are omitted. Also, the dimensional ratios among the components shown in the drawings do not necessarily indicate the actual dimensional ratios.
　図１は、本実施形態における表示装置１の概略構成を示す模式図である。表示装置１は、フィールドシーケンシャル方式でカラー画像を表示する液晶表示装置である。フィールドシーケンシャル方式は、１画面の表示期間すなわち１フレーム期間を分割してできる複数のサブフィールド毎に、異なる色の画面を表示することによって、カラー画像を表示する。 FIG. 1 is a schematic view showing a schematic configuration of a display device 1 in the present embodiment. The display device 1 is a liquid crystal display device that displays a color image by a field sequential method. In the field sequential method, a color image is displayed by displaying screens of different colors for each of a plurality of sub-fields that can be created by dividing a display period of one screen, that is, one frame period.
　表示装置１は、表示パネル１１、ゲートドライバ１２、ソースドライバ１３、表示制御回路１４、バックライト１５、バックライト制御回路１６、及び画像処理部１７を備える。 The display device 1 includes a display panel 11, a gate driver 12, a source driver 13, a display control circuit 14, a backlight 15, a backlight control circuit 16, and an image processing unit 17.
　表示パネル１１は、液晶を用いた表示パネルであり、複数のゲート線１１０と複数のソース線１１１とで形成される複数の画素がマトリクス状に形成されている。画素は、ゲート線１１０とソース線１１１とに接続された薄膜トランジスタ（ＴＦＴ）１１３と、ＴＦＴ１１３と接続された画素電極１１４とを有する。 The display panel 11 is a display panel using liquid crystal, and a plurality of pixels formed by a plurality of gate lines 110 and a plurality of source lines 111 are formed in a matrix. The pixel includes a thin film transistor (TFT) 113 connected to the gate line 110 and the source line 111, and a pixel electrode 114 connected to the TFT 113.
　ゲート線１１０は、ゲートドライバ１２と接続され、ソース線１１１は、ソースドライバ１３と接続されている。ゲートドライバ１２とソースドライバ１３は表示制御回路１４と接続されている。 The gate line 110 is connected to the gate driver 12, and the source line 111 is connected to the source driver 13. The gate driver 12 and the source driver 13 are connected to the display control circuit 14.
　ゲートドライバ１２は、表示制御回路１４からのタイミング信号やクロック信号等の制御信号に基づいて、各ゲート線１１０を順次走査する。ソースドライバ１３は、表示制御回路１４からのタイミング信号と画像信号に基づき、各ソース線１１１に画像信号に応じた電圧を印加する。ゲート線１１０が走査されるタイミングで、ゲート線１１０と接続されたＴＦＴ１１３がオン状態となり、ソース線１１１に供給される電圧が画素電極１１４に印加され、画素における液晶分子の配向が制御される。 The gate driver 12 sequentially scans the gate lines 110 based on control signals such as timing signals and clock signals from the display control circuit 14. The source driver 13 applies a voltage corresponding to the image signal to each source line 111 based on the timing signal and the image signal from the display control circuit 14. At the timing when the gate line 110 is scanned, the TFT 113 connected to the gate line 110 is turned on, a voltage supplied to the source line 111 is applied to the pixel electrode 114, and the alignment of liquid crystal molecules in the pixel is controlled.
　バックライト１５は、光源１５０と導光板１５１とを含む。光源１５０は、赤（Ｒ）、緑（Ｇ）、青（Ｂ）の各色で発光するＬＥＤ（Light Emitting Diode）１５Ｒ、１５Ｇ、１５Ｂを有する。 The backlight 15 includes a light source 150 and a light guide plate 151. The light source 150 includes LEDs (Light Emitting Diodes) 15R, 15G, and 15B that emit light of each color of red (R), green (G), and blue (B).
　導光板１５１は、表示パネル１の裏面側に設けられている。導光板１５１は、透明な材料で形成される。バックライト１５のうち表示パネル１１の表示画面、すなわち画素が配置される表示エリアと重なる部分は透明である。なお、図１では、光源１５０を導光板１５１の１つの側面に対向する位置に配置しているが、光源１５０を導光板１５１の複数の側面に対向する位置に配置することもできる。 The light guide plate 151 is provided on the back side of the display panel 1. The light guide plate 151 is formed of a transparent material. A portion of the backlight 15 overlapping the display screen of the display panel 11, that is, the display area where the pixels are arranged is transparent. Although the light source 150 is disposed at a position facing one side surface of the light guide plate 151 in FIG. 1, the light source 150 may be disposed at a position facing a plurality of side surfaces of the light guide plate 151.
　図２Ａ及び図２Ｂは、表示装置１の表示面に垂直な面の断面図である。図２Ａは、バックライト１５を消灯して表示装置１の後方が透けて見える透過領域を含む透過光画像を表示する状態の例を示す。図２Ｂは、バックライト１５を点灯してカラー画像を表示する状態の例を示す。 2A and 2B are cross-sectional views of a plane perpendicular to the display surface of the display device 1. FIG. 2A shows an example of a state in which the backlight 15 is turned off to display a transmitted light image including a transmission area seen behind the display device 1. FIG. 2B shows an example of a state in which the backlight 15 is turned on to display a color image.
　図２Ａ及び図２Ｂに示す例では、表示パネル１１は、バックライト１５と、表示画面に垂直な方向において重なる位置に設けられる。表示パネル１１は、２枚の第１基板２５及び第２基板２２と、これらの間に設けられる液晶２４を有する。第１基板２５の一方の面（例えば、バックライト１５と反対側の面）に、ゲート線１１０、ソース線１１１、及びスイッチング素子１１３及び画素電極１１４等が設けられる。第１基板２５の他方の面には、偏光板２６が設けられる。第２基板２２の一方の面（例えば、バックライト１５側の面）には、共通電極（図示せず）が形成される。第２基板２２の他方の面には、偏光板２１が設けられる。第１基板２５及び第２基板２２は、例えば、ガラス又は樹脂で形成することができる。 In the example shown in FIGS. 2A and 2B, the display panel 11 is provided at a position where the backlight 15 overlaps with the display screen in a direction perpendicular to the display screen. The display panel 11 includes two first and second substrates 25 and 22 and a liquid crystal 24 provided therebetween. The gate line 110, the source line 111, the switching element 113, the pixel electrode 114, and the like are provided on one surface of the first substrate 25 (for example, the surface opposite to the backlight 15). A polarizing plate 26 is provided on the other surface of the first substrate 25. A common electrode (not shown) is formed on one surface of the second substrate 22 (for example, the surface on the backlight 15 side). A polarizing plate 21 is provided on the other surface of the second substrate 22. The first substrate 25 and the second substrate 22 can be formed of, for example, glass or resin.
　バックライト１５の導光板１５１は、光源１５０からの光の入射面１５ａと、入射面１５ａから入った光源１５０の光を出射する出射面１５ｂとを有する。表示パネル１１は、導光板１５１の出射面１５ｂに重ねて設けられる。すなわち、バックライト１５は、表示パネル１１の一方の面に光を照射する照明部である。 The light guide plate 151 of the backlight 15 has an incident surface 15a of the light from the light source 150, and an emission surface 15b for emitting the light of the light source 150 that has entered from the incident surface 15a. The display panel 11 is provided so as to overlap the emission surface 15 b of the light guide plate 151. That is, the backlight 15 is an illumination unit that emits light to one surface of the display panel 11.
　図２Ａに示すように、導光板１５１の出射面１５ｂと対向する面である背面１５ｃにおいて、表示パネル１１の画像が表示される表示エリアすなわち表示画面と重なる領域は、光が透過可能となっている。バックライト１５は、表示パネル１１の表示画面と重なる部分は光が透過可能になるよう構成される。例えば、バックライト１５において、表示パネル１１の表示エリアと表示画面と垂直な方向において重なる位置に設けられる部材は、透明な材料で形成される。 As shown in FIG. 2A, in the back surface 15c, which is a surface facing the exit surface 15b of the light guide plate 151, light can be transmitted through the display area where the image of the display panel 11 is displayed, ie, the area overlapping the display screen. There is. The backlight 15 is configured such that light can be transmitted through a portion overlapping the display screen of the display panel 11. For example, in the backlight 15, a member provided at a position overlapping the display area of the display panel 11 in the direction perpendicular to the display screen is formed of a transparent material.
　具体的には、表示パネル１１の背面には、表示画面に垂直な方向に光が透過可能な導光板１５１が配置される。すなわち、表示パネル１１の背面に光を遮蔽する部材は配置されない。導光板１５１の背面側の部材には、アクリル板等の透明素材が用いられるか、又は、導光板１５１の背面に何も配置しない構成とすることができる。この構成により、表示パネル１１において光が透過するように液晶２４が制御された画素においては、表示装置１の後方から導光板１５１の背面を透過した光が、表示パネル１１の当該画素を通って表示画面の前方へ透過する。 Specifically, on the back of the display panel 11, a light guide plate 151 capable of transmitting light in the direction perpendicular to the display screen is disposed. That is, a member that shields light is not disposed on the back surface of the display panel 11. A transparent material such as an acrylic plate may be used as a member on the back side of the light guide plate 151, or nothing may be arranged on the back side of the light guide plate 151. With this configuration, in the pixels in which the liquid crystal 24 is controlled to transmit light in the display panel 11, light transmitted from the back of the display device 1 through the back surface of the light guide plate 151 passes through the pixels in the display panel 11. Transparent to the front of the display screen.
　また、図２Ｂに示すように、導光板１５１は、導光板１５１を伝播する光源１５０からの光が、表示パネル１１に対向する出射面１５ｂから表示パネル１１へ向けて出射しやすい構成となっている。例えば、導光板１５１の出射面１５ｂ及び背面１５ｃには、入射した光を反射するドット（図示せず）を所定の間隔で形成することができる。導光板１５１の入射面１５ａから入った光源１５０の光は、導光板１５１内を全反射しながら進む。導光板１５１の背面１５ｃのドットに入射した光源１５０からの光は、ドットに反射され、導光板１５１の出射面１５ｂから表示パネル１１へ向かって出射される。 Further, as shown in FIG. 2B, the light guide plate 151 is configured such that the light from the light source 150 propagating through the light guide plate 151 can be easily emitted toward the display panel 11 from the emission surface 15 b facing the display panel 11. There is. For example, dots (not shown) that reflect incident light can be formed at predetermined intervals on the emission surface 15 b and the back surface 15 c of the light guide plate 151. The light of the light source 150 that has entered from the incident surface 15 a of the light guide plate 151 travels while being totally reflected in the light guide plate 151. The light from the light source 150 that has entered the dots on the back surface 15 c of the light guide plate 151 is reflected by the dots and emitted from the emission surface 15 b of the light guide plate 151 toward the display panel 11.
　ドットは、例えば、白色不透明インク（有機系の紫外線硬化型インク等）又は金属インク（アルミニウム又は金等）の印刷等によって形成される。また、印刷によるドットの代わりに、金型プレス又はレーザー加工により導光板１５１の表面を光が反射しやすい形状に加工することができる。また、導光板１５１の表面の形状による反射を利用する形態に限られず、光を反射しやすい材質によって導光板１５１を形成してもよい。このように、導光板１５１は、内部を進む光を反射して外部に出射する反射構造を備えることができる。 The dots are formed, for example, by printing of a white opaque ink (organic UV curable ink or the like) or a metal ink (aluminum or gold or the like). Further, the surface of the light guide plate 151 can be processed into a shape that allows light to be easily reflected by die pressing or laser processing instead of dots by printing. Further, the light guide plate 151 may be formed of a material that easily reflects light without being limited to a form that utilizes reflection by the shape of the surface of the light guide plate 151. As described above, the light guide plate 151 can include a reflection structure that reflects light traveling inside and emits the light to the outside.
　このように、バックライト１５の点灯時には、光源１５０から導光板１５１を通って表示パネル１１に照射される光の量が、導光板１５１の背面１５ｃを透過して表示パネル１１に達する光の量に比べて多くなる。そのため、バックライト１５の点灯時には、表示パネル１１には、バックライト１５の光による色が表示され、表示装置１の後方が透けて見えることがなくなる。 Thus, when the backlight 15 is lit, the amount of light emitted from the light source 150 through the light guide plate 151 to the display panel 11 passes through the back surface 15 c of the light guide plate 151 and reaches the display panel 11 Compared to Therefore, when the backlight 15 is lit, the color by the light of the backlight 15 is displayed on the display panel 11, and the rear of the display device 1 is not seen through.
　表示装置１は、カラー表示モードと、透過光画像表示モードを有する。カラー表示モードでは、バックライト１５が点灯し、表示パネル１１は、表示装置１の後方が透けて見える透過領域を含まないカラー画像を表示する。透過光画像表示モードでは、バックライト１５が消灯し、表示パネル１１は、透過領域を含むモノトーン画像（透過光画像）を表示する。 The display device 1 has a color display mode and a transmitted light image display mode. In the color display mode, the backlight 15 is turned on, and the display panel 11 displays a color image that does not include a transmissive area that can be seen behind the display device 1. In the transmitted light image display mode, the backlight 15 is turned off, and the display panel 11 displays a monotone image (transmitted light image) including the transmitted area.
　表示パネル１１は、カラー表示モードと、透過光画像表示モードのいずれにおいても、上記パネル駆動部の信号に基づいて表示パネル１１に入射する光の透過率を画素毎に制御することで画像を表示する。カラー表示モードの場合すなわち、画像を表示する時にバックライト１５を点灯する場合、表示パネル１１は、光源１５０から導光板１５１内を伝播し出射面１５ｂを通って表示パネル１１へ入射する光の透過率を制御することになる。また、透過光画像表示モードの場合すなわち、画像を表示する時にバックライト１５を消灯する場合、表示パネル１１は、表示装置１の外側から導光板１５１の背面１５ｃを透過して表示パネル１１へ入射する光の透過率を制御することになる。これにより、透過領域を含む透過光画像を表示することができる。透過領域では、表示装置１の後方が透けて見える。 The display panel 11 displays an image by controlling the transmittance of light incident on the display panel 11 for each pixel based on the signal of the panel drive unit in any of the color display mode and the transmitted light image display mode. Do. In the case of the color display mode, that is, when the backlight 15 is turned on when displaying an image, the display panel 11 transmits the light from the light source 150 propagating in the light guide plate 151 and entering the display panel 11 through the emission surface 15 b. Will control the rate. In the transmitted light image display mode, that is, when the backlight 15 is turned off when displaying an image, the display panel 11 penetrates the back surface 15 c of the light guide plate 151 from the outside of the display device 1 and enters the display panel 11. Control the light transmission rate. Thereby, a transmitted light image including the transmission area can be displayed. In the transmissive region, the rear of the display device 1 can be seen through.
　図１に戻り、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂは、例えば、導光板１５１の一の側面に対向する位置に配置されている。ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂは、バックライト制御回路１６と接続されている。 Returning to FIG. 1, the LEDs 15 </ b> R, 15 </ b> G, and 15 </ b> B are disposed, for example, at positions facing one side surface of the light guide plate 151. The LEDs 15 R, 15 G, 15 B are connected to the backlight control circuit 16.
　バックライト制御回路１６は、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂをそれぞれ駆動するバックライト駆動回路（図示略）を含む。ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂのそれぞれは、対応するバックライト駆動回路から入力される点灯時間を指示するパルス信号に基づいて点灯する。 The backlight control circuit 16 includes a backlight drive circuit (not shown) that drives the LEDs 15R, 15G, and 15B. Each of the LEDs 15R, 15G, and 15B lights on the basis of a pulse signal indicating a lighting time input from the corresponding backlight drive circuit.
　表示制御回路１４とバックライト制御回路１６は画像処理部１７と接続されている。ここで、画像処理部１７の構成について説明する。 The display control circuit 14 and the backlight control circuit 16 are connected to the image processing unit 17. Here, the configuration of the image processing unit 17 will be described.
　図３は、画像処理部１７の構成例を示す機能ブロック図である。図３に示すように、画像処理部１７は、座標生成部１７１と、判定部１７２と、分離部１７３と、画像データ生成部１７４と、バックライトデータ生成部１７５と、タイミング制御部１７６とを備える。画像処理部１７は、例えば、フレーム（６０Ｈｚ）ごとの映像信号が入力される。 FIG. 3 is a functional block diagram showing a configuration example of the image processing unit 17. As shown in FIG. 3, the image processing unit 17 includes a coordinate generation unit 171, a determination unit 172, a separation unit 173, an image data generation unit 174, a backlight data generation unit 175, and a timing control unit 176. Prepare. The image processing unit 17 receives, for example, a video signal for each frame (60 Hz).
　座標生成部１７１は、表示パネル１１のゲート線１１０（図１参照）の延伸方向の水平総画素数と、ソース線１１１の延伸方向の垂直総ライン数とを保持するための外部から書き換え可能なレジスタを有する。座標生成部１７１は、映像信号に含まれる画素値（例えば、ＲＧＢの階調値）が入力されるごとに水平カウンタ値を１つ増加させる。水平カウンタ値がＭに等しくなると、次の画素値の入力で垂直カウンタ値を１つ増加させ、水平カウンタ値を１に戻す。座標生成部１７１は、映像信号が示す画像における左上の画素を原点（０，０）とし、水平方向をＸ方向、垂直方向をＹ方向として、入力される画素値の座標（ｘ，ｙ）を設定する。 The coordinate generation unit 171 can be externally rewritten to hold the total number of horizontal pixels in the extending direction of the gate lines 110 (see FIG. 1) of the display panel 11 and the total number of vertical lines in the extending direction of the source lines 111. It has a register. The coordinate generation unit 171 increments the horizontal counter value by one each time a pixel value (for example, a gradation value of RGB) included in the video signal is input. When the horizontal counter value becomes equal to M, the vertical counter value is incremented by one at the input of the next pixel value, and the horizontal counter value is returned to 1. The coordinate generation unit 171 sets the upper left pixel in the image represented by the video signal as the origin (0, 0), the horizontal direction as the X direction, and the vertical direction as the Y direction, and coordinates (x, y) of the input pixel value. Set
　判定部１７２は、入力された映像信号に含まれる画素値が、予め定められた座標の画素値であるか否かを判定し、判定結果を分離部１７３へ出力する。本実施形態では、判定部１７２は、入力された映像信号に含まれる画素値の座標（ｘ、ｙ）が、例えば（０，０）であるか否かを判定する。つまり、判定部１７２は、映像信号に含まれる画素値のうち、座標（０，０）の画素値を、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの点灯／消灯制御に用いる。 The determination unit 172 determines whether the pixel value included in the input video signal is a pixel value of a predetermined coordinate, and outputs the determination result to the separation unit 173. In the present embodiment, the determination unit 172 determines whether the coordinates (x, y) of the pixel value included in the input video signal are, for example, (0, 0). That is, the determination unit 172 uses the pixel value of the coordinate (0, 0) among the pixel values included in the video signal for the on / off control of the LEDs 15R, 15G, and 15B.
　映像信号に含まれるデータは、画像の表示期間に対応する部分とブランキング期間に対応する部分とを有する場合もある。この場合、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの点灯／消灯を制御するデータは、ブランキング期間に対応する部分に含ませることができる。１フレーム期間は、画像表示期間とブランキング期間に分けられる。これに対応して、１フレーム期間の画素値は、画像表示期間に対応する部分とブランキング期間に対する部分とを有する。画像表示期間に対応する部分には、各ＴＦＴ１１３に対応して、各画素の階調値等のデータが含まれる。ブランキング期間に対応する部分には、当該フレーム期間においてＬＥＤ１５Ｒ、１５Ｇ、１５Ｂを点灯させるか否かを示す制御データが含まれる。 The data included in the video signal may have a portion corresponding to the display period of the image and a portion corresponding to the blanking period. In this case, data for controlling turning on / off of the LEDs 15R, 15G, and 15B can be included in a portion corresponding to the blanking period. One frame period is divided into an image display period and a blanking period. Corresponding to this, the pixel value of one frame period has a portion corresponding to the image display period and a portion for the blanking period. The portion corresponding to the image display period includes data such as the gradation value of each pixel corresponding to each TFT 113. The portion corresponding to the blanking period includes control data indicating whether to turn on the LEDs 15R, 15G, and 15B in the frame period.
　判定部１７２は、判定結果として、各座標の画素値が、表示すべき画像の階調値であるか、ＬＥＤの点灯／消灯を表す制御データであるかを示す情報を分離部１７３へ出力する。 The determination unit 172 outputs, as a determination result, to the separation unit 173, information indicating whether the pixel value of each coordinate is the gradation value of the image to be displayed or the control data representing the on / off of the LED. .
　分離部１７３は、判定部１７２の判定結果に従って、入力される映像信号の各画素値から、表示すべき画像を示す画像データと、ＬＥＤの制御データとを分離する。画像データは、画像データ生成部１７４に出力され、ＬＥＤの制御データはバックライトデータ生成部１７５に出力される。 The separating unit 173 separates the image data indicating the image to be displayed and the control data of the LED from each pixel value of the input video signal according to the determination result of the determining unit 172. The image data is output to the image data generation unit 174, and the control data of the LED is output to the backlight data generation unit 175.
　画像データ生成部１７４は、１フレームを分割してできる複数のサブフィールドのそれぞれの期間に表示するためのサブフィールド画像データを、入力された画像データに基づいて生成する。この例では、ＲＧＢそれぞれの色の階調値を含む画像データから、フィールドシーケンシャル表示を行うための表示データとして、ＲＧＢそれぞれの色に、混合色Ｗ（白色）を加えたＷＲＧＢのそれぞれの色に対応するサブフィールド画像を生成する。生成されたサブフィールド画像は、タイミング制御部１７６へ出力される。 The image data generation unit 174 generates subfield image data to be displayed in each period of a plurality of subfields formed by dividing one frame based on the input image data. In this example, as image display data for performing field sequential display from image data including gradation values of respective colors of RGB, mixed colors W (white) are added to the respective colors of RGB to respective colors of WRGB. Generate a corresponding subfield image. The generated subfield image is output to the timing control unit 176.
　バックライトデータ生成部１７５は、ＷＲＧＢの各色に対応するサブフィールド期間において、それぞれ対応する色のＬＥＤを発光させるＬＥＤ制御データを生成し、タイミング制御部１７６へ出力する。例えば、バックライトデータ生成部１７５及びタイミング制御部１７６は、Ｗ（白色）に対応するサブフィールド期間ではＬＥＤ１５Ｒ、１５Ｇ、１５Ｂを同時に発光させ、Ｒに対応するサブフィールド期間にはＬＥＤ１５Ｒ、Ｇに対応するサブフィールド期間にはＬＥＤ１５Ｇ、１５Ｂに対応するサブフィールド期間にはＬＥＤ１５Ｂがそれぞれ発光するよう制御する。 The backlight data generation unit 175 generates LED control data for causing the LEDs of the corresponding colors to emit light in the subfield period corresponding to each color of WRGB, and outputs the generated data to the timing control unit 176. For example, the backlight data generation unit 175 and the timing control unit 176 simultaneously cause the LEDs 15R, 15G, and 15B to emit light in the subfield period corresponding to W (white), and correspond to the LEDs 15R and G in the subfield period corresponding to R. The LED 15B is controlled to emit light in the subfield periods corresponding to the LEDs 15G and 15B, respectively.
　また、バックライトデータ生成部１７５は、画素値で示される画像を表示する時にＬＥＤの点灯／消灯を表す制御データに基づいて、フレーム毎に、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの点灯／消灯を表すバックライトデータを生成する。例えば、座標（０，０）の画素値に含まれるＲＧＢそれぞれの階調値（Ｒ，Ｇ，Ｂ）が閾値より大きい場合は、その画像データを表示するフレーム期間においてＬＥＤ１５Ｒ、１５Ｇ、１５Ｂを点灯させるバックライトデータを生成する。一方、上記階調値（Ｒ、Ｇ、Ｂ）が閾値未満の場合は、そのフレーム期間においてＬＥＤ１５Ｒ、１５Ｇ、１５Ｂを消灯させるバックライトデータを生成する。階調の最大が２５５階調の場合、例えば、閾値を１２８とし、バックライトデータ生成部１７５は、座標（０，０）の画素値に含まれる階調値が（０，０，０）であれば、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂに消灯を指示するバックライトデータを生成する。また、座標（０，０）の画素値に含まれる階調値が（２５５，２５５，２５５）であれば、バックライトデータ生成部１７５は、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂに点灯を指示するバックライトデータを生成する。生成されたバックライトデータは、画像データ生成部１７４及びタイミング制御部１７６へ入力される。 In addition, the backlight data generation unit 175 is a backlight that represents lighting / extinguishing of the LEDs 15R, 15G, and 15B for each frame based on control data that represents lighting / extinguishing of the LED when displaying an image indicated by a pixel value. Generate data. For example, when each of the RGB gradation values (R, G, B) included in the pixel value of the coordinates (0, 0) is larger than the threshold, the LEDs 15R, 15G, 15B are turned on in the frame period for displaying the image data. Generate backlight data. On the other hand, when the gradation value (R, G, B) is less than the threshold value, backlight data is generated to turn off the LEDs 15R, 15G, 15B in the frame period. When the maximum gradation is 255, for example, the threshold value is 128, and the backlight data generation unit 175 determines that the gradation value included in the pixel value at the coordinate (0, 0) is (0, 0, 0). If there is, backlight data is generated that instructs the LEDs 15R, 15G, and 15B to turn off. In addition, when the gradation value included in the pixel value at the coordinate (0, 0) is (255, 255, 255), the backlight data generation unit 175 instructs the LED 15R, 15G, 15B to turn on the backlight data Generate The generated backlight data is input to the image data generation unit 174 and the timing control unit 176.
　なお、ＬＥＤの点灯／消灯を表す制御データの検出処理は、上記例に限られない。上記例では、入力された画素値に点灯か否かを示す制御データが含まれる形態であるが、画素値に加えて、この制御データが別途入力されてもよい。例えば、画素値と同時に、又は画素値に対応づけられて点灯／消灯を表す制御データが入力されてもよい。この場合、画像処理部１７は、制御データを、１フレーム期間の画素値と同期させて、又は１フレーム期間の画素値に対応付けて、バックライトデータ生成部１７５又はタイミング制御部１７６へ入力する。 In addition, the detection process of the control data showing ON / OFF of LED is not restricted to the said example. In the above-described example, the input pixel value includes control data indicating whether or not lighting is performed. However, in addition to the pixel value, this control data may be separately input. For example, control data representing lighting / extinguishing may be input simultaneously with the pixel value or in association with the pixel value. In this case, the image processing unit 17 inputs the control data to the backlight data generation unit 175 or the timing control unit 176 in synchronization with the pixel value of one frame period or in association with the pixel value of one frame period. .
　タイミング制御部１７６は、ＷＲＧＢそれぞれのサブフィールド画像の表示と、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの点灯とを同期させるためのタイミング制御を行う。タイミング制御部１７６は、ＲＧＢそれぞれの色及びこれらの混合色Ｗを照射するタイミングと、ＷＲＧＢそれぞれのサブフィールド画像を表示するタイミングとを同期させるタイミング制御信号を、表示制御回路１４（図１参照）及びバックライト制御回路１６（図１参照）に出力する。 The timing control unit 176 performs timing control for synchronizing the display of subfield images of WRGB with the lighting of the LEDs 15R, 15G, and 15B. The timing control unit 176 controls the timing control signal 14 to synchronize the timing of irradiating each color of RGB and the mixed color W with the timing of displaying each subfield image of WRGB as shown in FIG. And the backlight control circuit 16 (see FIG. 1).
　図１に戻り、表示制御回路１４は、タイミング制御部１７６から入力されるＷＲＧＢの各サブフィールド画像とタイミング制御信号とに基づいて、ゲートドライバ１２とソースドライバ１３のそれぞれに対し、表示パネル１１を駆動させるためのタイミング信号等の制御信号を入力する。 Returning to FIG. 1, the display control circuit 14 displays the display panel 11 for each of the gate driver 12 and the source driver 13 based on each sub-field image of WRGB input from the timing control unit 176 and the timing control signal. A control signal such as a timing signal for driving is input.
　バックライト制御回路１６は、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂのそれぞれを駆動するためのＬＥＤ駆動回路（図示略）を備える。バックライト制御回路１６は、表示制御回路１４によって、ＷＲＧＢの各色のサブフィールド画像が表示パネル１１に表示されるタイミングに合わせて、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの発光色を切り替える。つまり、バックライト制御回路１６は、タイミング制御部１７６から入力されるタイミング制御信号に基づいて、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂに対応する各ＬＥＤ駆動回路（図示略）により、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの点灯と消灯を制御する。 The backlight control circuit 16 includes an LED drive circuit (not shown) for driving each of the LEDs 15R, 15G, and 15B. The backlight control circuit 16 switches the light emission colors of the LEDs 15R, 15G, and 15B in accordance with the timing when the subfield image of each color of WRGB is displayed on the display panel 11 by the display control circuit 14. That is, the backlight control circuit 16 turns on the LEDs 15R, 15G, and 15B by the LED drive circuits (not shown) corresponding to the LEDs 15R, 15G, and 15B based on the timing control signal input from the timing control unit 176. Control the light off.
　また、バックライト制御回路１６は、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂが消灯状態から、カラー画像表示のための点灯を開始するまでの一定期間、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂのそれぞれを駆動する各ＬＥＤ駆動回路（図示略）を、所定の定電流が出力される定常状態にするための調整処理を行う。そして調整処理後、各ＬＥＤ駆動回路は、予めなされたホワイトバランス調整の結果に応じてＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの点灯時間を制御し、カラー画像表示のための点灯を開始する。ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの各点灯時間は、ＰＷＭ（Pulse Width Modulation）変調方式でパルス幅が調整されたパルス信号によって制御される。 In addition, the backlight control circuit 16 drives each of the LEDs 15R, 15G, and 15B for a certain period of time from when the LEDs 15R, 15G, and 15B are turned off to when lighting for color image display starts (shown in FIG. An adjustment process is performed to bring the output signal into a steady state in which a predetermined constant current is output. Then, after the adjustment processing, each LED drive circuit controls the lighting time of the LEDs 15R, 15G, and 15B according to the result of the white balance adjustment made in advance, and starts lighting for color image display. Each lighting time of LED15R, 15G, 15B is controlled by the pulse signal by which the pulse width was adjusted by the PWM (Pulse Width Modulation) modulation system.
　ここで、本実施形態におけるＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの各ＬＥＤ駆動回路（図示略）の調整処理について具体的に説明する。図４は、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂに対して出力されるパルス信号の波形の一例である。 Here, the adjustment process of each LED drive circuit (not shown) of LED15R, 15G, 15B in this embodiment is demonstrated concretely. FIG. 4 is an example of waveforms of pulse signals output to the LEDs 15R, 15G, and 15B.
　図４において、１フレーム目～Ｎ－１（Ｎ：３以上の整数）フレーム（図示略）の期間Ｔ１は、調整処理期間におけるＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの点灯状態を示している。調整処理期間Ｔ１は、各ＬＥＤ駆動回路が定常状態となる前の過渡状態の期間である。Ｎフレーム目以降の期間Ｔ２は、各ＬＥＤ駆動回路が定常状態に遷移した後のＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの点灯状態を示している。この例では、６０Ｈｚで１フレームごとに映像信号が入力され、１フレーム期間は、ＷＲＧＢに対応する４つのサブフィールドＦ１～Ｆ４に分割される。１つのサブフィールドの周波数は、映像信号の周波数の４倍の２４０Ｈｚとなる。サブフィールドＦ１～Ｆ４の各期間では、ＷＲＧＢの各色に対応するサブフィールド画像がそれぞれ表示される。 In FIG. 4, a period T1 of the first frame to N-1 (N: an integer of 3 or more) frame (not shown) indicates the lighting state of the LEDs 15R, 15G, 15B in the adjustment processing period. The adjustment processing period T1 is a period of a transient state before each LED drive circuit enters a steady state. A period T2 after the Nth frame indicates the lighting state of the LEDs 15R, 15G, and 15B after each LED drive circuit has transitioned to the steady state. In this example, a video signal is input at 60 Hz for each frame, and one frame period is divided into four subfields F1 to F4 corresponding to WRGB. The frequency of one subfield is 240 Hz, which is four times the frequency of the video signal. In each period of subfields F1 to F4, subfield images corresponding to each color of WRGB are displayed.
　図４に示すように、調整処理期間Ｔ１は、各ＬＥＤ駆動回路が過渡状態であり、各フレームおける全てのサブフィールドＦ１～Ｆ４において、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂを同時に点灯させる。ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂのそれぞれに対するパルス信号はパルス幅が同等である。これにより、Ｆ１～Ｆ４の各サブフィールド期間において、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂは略同じ点灯時間で点灯する。 As shown in FIG. 4, in the adjustment processing period T1, each LED drive circuit is in a transient state, and simultaneously turns on the LEDs 15R, 15G, and 15B in all subfields F1 to F4 in each frame. The pulse signals for each of the LEDs 15R, 15G, and 15B have the same pulse width. Thus, the LEDs 15R, 15G, and 15B are lighted in substantially the same lighting time in each subfield period of F1 to F4.
　そして、調整処理期間Ｔ１後、つまり、各ＬＥＤ駆動回路が定常状態に遷移した後のＮフレーム目の各サブフィールドＦ１～Ｆ４では、ホワイトバランス調整に応じたＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの各点灯時間となるように、それぞれのパルス信号のパルス幅が調整される。この例では、点灯時間が、ＬＥＤ１５Ｂ＜ＬＥＤ１５Ｇ＜ＬＥＤ１５Ｒの関係を満たすようにパルス幅が調整されている。 Then, after the adjustment processing period T1, that is, in each subfield F1 to F4 of the Nth frame after each LED drive circuit transitions to the steady state, the lighting time of each of the LEDs 15R, 15G, and 15B according to the white balance adjustment Thus, the pulse widths of the respective pulse signals are adjusted. In this example, the pulse width is adjusted so that the lighting time satisfies the relationship of LED15B <LED15G <LED15R.
　つまり、図４に示すＮフレーム目において、サブフィールドＦ１では、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂは、互いに異なるパルス幅のパルス信号に応じて点灯し、Ｗのサブフィールド画像を表示させる。サブフィールドＦ２では、ＬＥＤ１５Ｒのみ、ＬＥＤ１５Ｒのパルス信号に応じた点灯時間で点灯し、Ｒのサブフィールド画像を表示させる。サブフィールドＦ３では、ＬＥＤ１５Ｇのみ、ＬＥＤ１５Ｇのパルス信号に応じた点灯時間で点灯し、Ｇのサブフィールド画像を表示させる。サブフィールドＦ４では、ＬＥＤ１５Ｂのみ、ＬＥＤ１５Ｂのパルス信号に応じた点灯時間で点灯し、Ｂのサブフィールド画像を表示させる。 That is, in the subfield F1 in the N-th frame shown in FIG. 4, the LEDs 15R, 15G, and 15B are turned on in response to pulse signals having pulse widths different from one another, and a W subfield image is displayed. In the subfield F2, only the LED 15R is turned on in the lighting time corresponding to the pulse signal of the LED 15R, and the R subfield image is displayed. In the sub-field F3, only the LED 15G lights up in the lighting time according to the pulse signal of the LED 15G, and the sub-field image of G is displayed. In the sub-field F4, only the LED 15B lights up in the lighting time according to the pulse signal of the LED 15B, and the sub-field image of B is displayed.
　なお、上記各ＬＥＤ駆動回路の調整処理期間Ｔ１の各サブフィールドにおけるＬＥＤ１５Ｒ、１５Ｇ、１５Ｂのそれぞれの点灯時間は、各ＬＥＤ駆動回路が定常状態に遷移した後、カラー画像表示のための点灯開始時におけるＬＥＤ１５Ｒ、１５Ｇ、１５Ｂのそれぞれの点灯時間よりも長くする。これにより、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂのそれぞれを駆動するＬＥＤ駆動回路（図示略）が、画像表示のための点灯開始時に、対応するＬＥＤに所定の定電流を出力する定常状態となるまでの時間を短くすることができる。 The lighting time of each of the LEDs 15R, 15G, and 15B in each subfield of the adjustment processing period T1 of each LED driving circuit is the lighting start time for color image display after each LED driving circuit transitions to the steady state. It makes longer than each lighting time of LED15R, 15G, and 15B in. Thereby, the time until the LED drive circuit (not shown) which drives each of LED15R, 15G, and 15B becomes a steady state which outputs a predetermined | prescribed constant current to corresponding LED at the time of the lighting start for an image display starts It can be shortened.
　各ＬＥＤ駆動回路の調整処理期間Ｔ１において、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの点灯時間に差がある場合、カラー画像表示を行うための点灯開始時に、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂのそれぞれを駆動させる各ＬＥＤ駆動回路（図示略）が、対応するＬＥＤに対して所定の定電流を出力する定常状態となるまでの時間にばらつきが生じる。上記実施形態では、各ＬＥＤ駆動回路の調整処理期間Ｔ１において、フレームごとの各サブフィールドで、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂを同時に同じ点灯時間で点灯させる。そのため、カラー画像表示を行うための点灯開始時に、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの各ＬＥＤ駆動回路（図示略）が定常状態に遷移する時間がばらつかず、意図しない色で画像表示されることを防止することができる。 When there is a difference in the lighting time of the LEDs 15R, 15G, and 15B in the adjustment processing period T1 of each LED driving circuit, each LED driving circuit that drives each of the LEDs 15R, 15G, and 15B at the start of lighting for performing color image display A variation occurs in the time until the steady state (not shown) outputs a predetermined constant current to the corresponding LED. In the above embodiment, in the adjustment processing period T1 of each LED drive circuit, the LEDs 15R, 15G, and 15B are simultaneously lit in the same lighting time in each subfield of each frame. Therefore, at the start of lighting for performing color image display, the time when the LED drive circuits (not shown) of the LEDs 15R, 15G, and 15B (not shown) transition to the steady state does not vary, preventing image display in unintended colors can do.
　なお、各ＬＥＤ駆動回路の調整処理期間Ｔ１は、表示パネル１１において黒色の画像が表示されるように、表示制御回路１４（図１参照）により、表示パネル１１における液晶分子の配向を制御してもよい。表示パネル１１を黒色表示することで、さらに、意図しない色での表示を防止することができる。 During the adjustment processing period T1 of each LED drive circuit, the orientation of liquid crystal molecules in the display panel 11 is controlled by the display control circuit 14 (see FIG. 1) so that a black image is displayed on the display panel 11. It is also good. By displaying the display panel 11 in black, display in an unintended color can be further prevented.
　以上、本発明に係る表示装置の一例について説明したが、本発明に係る表示装置は、上述した実施形態の構成に限定されず、様々な変形構成とすることができる。 As mentioned above, although an example of a display concerning the present invention was explained, a display concerning the present invention is not limited to composition of an embodiment mentioned above, and can be considered as various modification composition.
　上述した実施形態では、１フレームをＷＲＧＢの各色に対応する４つのサブフィールドに分割する例を説明したが、１フレームを、ＲＧＢの各色に対応する３つのサブフィールドに分割してもよい。この場合には、図４に示すように、１フレーム期間を３つのサブフィールドＦ１～Ｆ３に分割する。１フレームが６０Ｈｚの場合、サブフィールドは１８０Ｈｚとなる。 In the embodiment described above, an example in which one frame is divided into four subfields corresponding to each color of WRGB is described, but one frame may be divided into three subfields corresponding to each color of RGB. In this case, as shown in FIG. 4, one frame period is divided into three subfields F1 to F3. When one frame is 60 Hz, the sub-field is 180 Hz.
　この場合においても、各ＬＥＤ駆動回路の調整処理期間Ｔ１では、フレームごとの全てのサブフィールドＦ１～Ｆ３において、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂのそれぞれに対するパルス信号のパルス幅は同等にする。これにより、各ＬＥＤ駆動回路の調整処理期間Ｔ１における各サブフィールド期間は、ＬＥＤ１５Ｒ、１５Ｇ、１５Ｂが略同じ点灯時間で点灯する。 Also in this case, in the adjustment processing period T1 of each LED drive circuit, the pulse width of the pulse signal for each of the LEDs 15R, 15G, and 15B is equal in all subfields F1 to F3 for each frame. Thus, in each subfield period in the adjustment processing period T1 of each LED drive circuit, the LEDs 15R, 15G, and 15B light up in substantially the same lighting time.
　各ＬＥＤ駆動回路が定常状態に遷移後のＮフレーム目以降は、ホワイトバランス調整に応じたＬＥＤ１５Ｒ、１５Ｇ、１５Ｂの点灯時間となるように各パルス信号のパルス幅が調整される。この例では、上述の実施形態と同様、ＬＥＤ１５Ｂ、１５Ｇ、１５Ｒの順に点灯時間が長くなるようにパルス幅が調整される。つまり、図５に示すように、Ｎフレーム目のサブフィールドＦ１では、ＬＥＤ１５Ｒのみホワイトバランス調整に応じた点灯時間で点灯し、Ｒのサブフィールド画像が表示される。また、サブフィールドＦ２では、ＬＥＤ１５Ｇのみホワイトバランス調整に応じた点灯時間で点灯し、Ｇのサブフィールド画像が表示される。また、サブフィールドＦ３では、ＬＥＤ１５Ｂのみホワイトバランス調整に応じた点灯時間で点灯し、Ｂのサブフィールド画像が表示される。 The pulse width of each pulse signal is adjusted so as to become the lighting time of the LEDs 15R, 15G, and 15B according to the white balance adjustment after the Nth frame after each LED drive circuit transitions to the steady state. In this example, the pulse width is adjusted so that the lighting time becomes longer in the order of the LEDs 15B, 15G, and 15R, as in the above-described embodiment. That is, as shown in FIG. 5, in the subfield F1 of the Nth frame, only the LED 15R lights up in the lighting time according to the white balance adjustment, and the R subfield image is displayed. Further, in the sub-field F2, only the LED 15G is turned on in the lighting time according to the white balance adjustment, and the sub-field image of G is displayed. Further, in the sub-field F3, only the LED 15B lights up in the lighting time according to the white balance adjustment, and the sub-field image of B is displayed.
　（２）本発明を適用できる表示装置は、液晶表示装置に限られない。表示パネルの一方の面に光を照射する照明部を備え、表示画面の後方を透けて見せる機能を有する他の表示装置（液晶表示装置以外の表示装置）にも、本発明を適用することができる。例えば、２次元状に配置され、光を通過させるオン状態と、光を遮断するオフ状態を画素ごとに制御可能な複数のシャッター素子を含む表示パネルと、バックライトとを備え、１フレーム期間において複数回、画像データの各ビットに応じてシャッター素子のオン状態とオフ状態を切り替える表示装置にも適用することができる。 (2) The display device to which the present invention can be applied is not limited to the liquid crystal display device. The present invention may be applied to other display devices (display devices other than liquid crystal display devices) having an illumination unit that emits light on one surface of the display panel and having a function to show through the back of the display screen. it can. For example, the display panel includes a display panel including a plurality of shutter elements arranged two-dimensionally to transmit light, capable of controlling an off state to block light for each pixel, and a backlight, in one frame period. The present invention can also be applied to a display device that switches the on state and the off state of the shutter element a plurality of times in accordance with each bit of the image data.
　１…表示装置、１１…表示パネル、１２…ゲートドライバ、１３…ソースドライバ、１４…表示制御回路、１５…バックライト、１５Ｒ，１５Ｇ，１５Ｂ…ＬＥＤ、１６…バックライト制御回路、１７…画像処理部、１５０…光源、１５１…導光板、１７１…座標生成部、１７２…判定部、１７３…分離部、１７４…画像データ生成部、１７５…バックライトデータ生成部、１７６…タイミング制御部 DESCRIPTION OF SYMBOLS 1 ... Display apparatus, 11 ... Display panel, 12 ... Gate driver, 13 ... Source driver, 14 ... Display control circuit, 15 ... Backlight, 15R, 15G, 15B ... LED, 16 ... Backlight control circuit, 17 ... Image processing Unit 150 Light source 151 Light guide plate 171 Coordinate generation unit 172 Determination unit 173 Separation unit 174 Image data generation unit 175 Backlight data generation unit 176 Timing control unit

Claims (5)

  1. 　互いに異なる色で発光する複数の光源を備え、１フレームを分割したサブフィールドごとに、前記複数の光源のそれぞれを順次点灯させるフィールドシーケンシャル方式で画像表示を行う表示装置であって、
    　入力される映像信号に基づいて、前記複数の光源のそれぞれの点灯を制御する発光制御部を備え、
    　前記発光制御部は、前記複数の光源の消灯状態からカラー画像表示のための点灯開始までの所定期間において、前記サブフィールドごとに、それぞれの点灯時間が同等となるように前記複数の光源を点灯させ、当該所定期間の経過後、予めなされたホワイトバランス調整の結果に応じて前記複数の光源の点灯時間を制御する、表示装置。     A display device comprising a plurality of light sources emitting light in different colors and performing image display according to a field sequential method in which each of the plurality of light sources is sequentially turned on in each subfield obtained by dividing one frame,
    A light emission control unit configured to control lighting of each of the plurality of light sources based on an input video signal;
    The light emission control unit turns on the plurality of light sources such that the lighting time is equal for each of the subfields in a predetermined period from the turn-off state of the plurality of light sources to the start of lighting for displaying a color image. A display device which controls the lighting time of the plurality of light sources according to the result of the white balance adjustment made in advance after the lapse of the predetermined period.
  2. 　複数の画素を有する表示パネルと、
    　前記映像信号に基づいて、前記表示パネルにおける画素の透過率を制御する表示制御部と、をさらに備え、
    　前記表示制御部は、前記所定期間の間、黒色表示となるように前記画素の透過率を制御する、請求項１に記載の表示装置。     A display panel having a plurality of pixels,
    And a display control unit configured to control the transmittance of pixels in the display panel based on the video signal.
    The display device according to claim 1, wherein the display control unit controls the transmittance of the pixel so as to display black during the predetermined period.
  3. 　前記所定期間における前記複数の光源の点灯時間は、前記所定期間の経過後の前記複数の光源の点灯時間よりも長い、請求項１又は２に記載の表示装置。 The display device according to claim 1, wherein a lighting time of the plurality of light sources in the predetermined period is longer than a lighting time of the plurality of light sources after the lapse of the predetermined period.
  4. 　前記複数の光源は、赤（Ｒ）、緑（Ｇ）、青（Ｂ）のそれぞれの色で発光する光源を有し、
    　前記１フレームを分割したサブフレームは、白（Ｗ）、赤（Ｒ）、緑（Ｇ）、青（Ｂ）の各色に対応する画像データを順次表示させる４つのサブフィールドである、請求項１から３のいずれか一項に記載の表示装置。     The plurality of light sources include light sources emitting light of respective colors of red (R), green (G), and blue (B),
    The sub-frames obtained by dividing one frame are four sub-fields in which image data corresponding to each color of white (W), red (R), green (G), and blue (B) are sequentially displayed. The display apparatus as described in any one of to 3.
  5. 　前記複数の光源は、赤（Ｒ）、緑（Ｇ）、青（Ｂ）のそれぞれの色で発光する光源を有し、
    　前記１フレームを分割したサブフレームは、赤（Ｒ）、緑（Ｇ）、青（Ｂ）の各色に対応する画像データを順次表示させる３つのサブフィールドである、請求項１から３のいずれか一項に記載の表示装置。     The plurality of light sources include light sources emitting light of respective colors of red (R), green (G), and blue (B),
    The sub-frame obtained by dividing one frame is three sub-fields in which image data corresponding to each color of red (R), green (G) and blue (B) are sequentially displayed. The display device according to one item.
PCT/JP2018/029536 2017-08-09 2018-08-07 Display device WO2019031479A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001215466A (en) * 2000-02-03 2001-08-10 Ichikoh Ind Ltd Back-light for color liquid crystal display device
JP2008249998A (en) * 2007-03-30 2008-10-16 Nec Lcd Technologies Ltd Backlight device and liquid crystal display device
JP2010107579A (en) * 2008-10-28 2010-05-13 Seiko Epson Corp Driving method and electro-optical device
JP2017111165A (en) * 2015-12-14 2017-06-22 日本精機株式会社 Light source device, display, and head-up display device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001215466A (en) * 2000-02-03 2001-08-10 Ichikoh Ind Ltd Back-light for color liquid crystal display device
JP2008249998A (en) * 2007-03-30 2008-10-16 Nec Lcd Technologies Ltd Backlight device and liquid crystal display device
JP2010107579A (en) * 2008-10-28 2010-05-13 Seiko Epson Corp Driving method and electro-optical device
JP2017111165A (en) * 2015-12-14 2017-06-22 日本精機株式会社 Light source device, display, and head-up display device

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