WO2021149347A1 - Dispositif d'affichage à cristaux liquides - Google Patents

Dispositif d'affichage à cristaux liquides Download PDF

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Publication number
WO2021149347A1
WO2021149347A1 PCT/JP2020/043786 JP2020043786W WO2021149347A1 WO 2021149347 A1 WO2021149347 A1 WO 2021149347A1 JP 2020043786 W JP2020043786 W JP 2020043786W WO 2021149347 A1 WO2021149347 A1 WO 2021149347A1
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Prior art keywords
liquid crystal
blue light
light
crystal display
display device
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Application number
PCT/JP2020/043786
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English (en)
Japanese (ja)
Inventor
敦幸 田中
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シャープ株式会社
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Publication of WO2021149347A1 publication Critical patent/WO2021149347A1/fr

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S2/00—Systems of lighting devices, not provided for in main groups F21S4/00 - F21S10/00 or F21S19/00, e.g. of modular construction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V3/00—Globes; Bowls; Cover glasses
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V3/00—Globes; Bowls; Cover glasses
    • F21V3/04—Globes; Bowls; Cover glasses characterised by materials, surface treatments or coatings
    • F21V3/10—Globes; Bowls; Cover glasses characterised by materials, surface treatments or coatings characterised by coatings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V5/00—Refractors for light sources
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V7/00—Reflectors for light sources
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
    • F21V9/20—Dichroic filters, i.e. devices operating on the principle of wave interference to pass specific ranges of wavelengths while cancelling others
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
    • F21V9/30—Elements containing photoluminescent material distinct from or spaced from the light source
    • F21V9/38—Combination of two or more photoluminescent elements of different materials
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/22—Absorbing filters
    • 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
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices

Definitions

  • the present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device provided with a direct-type backlight.
  • the backlight used in the liquid crystal display is roughly divided into an edge light type method in which an LED (Light Emitting Diode) is provided at the end of the light guide plate and a direct type method in which a plurality of LEDs are spread on the back side of the liquid crystal panel. NS.
  • the direct type backlight will be described.
  • FIG. 12 is a diagram showing a transmission path of blue light emitted when only one blue LED 11 is turned on in a conventional liquid crystal display device provided with a direct-type backlight 180.
  • the direct type backlight 180 (hereinafter, may be simply referred to as “backlight”), the LED substrate 10 on which the blue LED 11 is arranged is provided above the LED substrate 10 with a predetermined interval OD.
  • the first diffusion plate 20, the wavelength conversion sheet 50, the optical sheet 60, and the brightness increasing film 70 are laminated in this order.
  • the liquid crystal panel 90 is arranged on the backlight 180.
  • the wavelength conversion sheet 50 includes a red fluorescent sheet coated with a phosphor that emits red light (not shown) and a green fluorescent sheet coated with a phosphor that emits green light (not shown). Therefore, when the blue light emitted from the blue LED 11 is incident, the wavelength conversion sheet 50 converts a part of the blue light into red light and green light, and emits the blue light together with the blue light that is not converted into either of them. When the red light and the green light enter the viewer's eyes at the same time, the viewer recognizes the light as yellow light. Therefore, in the present specification and drawings, red light and green light may be collectively referred to as yellow light.
  • the blue light and yellow light emitted from the wavelength conversion sheet 50 pass through the optical sheet 60 and enter the brightness increasing film 70.
  • the whitish light consisting of blue light and yellow light that coincides with the polarization direction of the polarizing plate 91 provided on the back surface side of the liquid crystal panel 90 passes through the brightness increasing film 70 and the polarizing plate 91 and enters the liquid crystal panel 90. do.
  • the other blue light and yellow light are reflected by the luminance increasing film 70, then recycled so as to match the polarization direction of the polarizing plate 91, enter the LED substrate 10, and are reflected by the LED substrate 10.
  • a part of the blue light contained in the whitish light reflected by the LED substrate 10 is converted into green light and red light by the wavelength conversion sheet 50.
  • the whitish light transmitted through the wavelength conversion sheet 50 includes newly converted green light and red light, it is emitted as yellowish light and incident on the luminance increasing film 70.
  • the brightness-increasing film transmits light that coincides with the polarization direction of the polarizing plate 91 and reflects other light. As a result, only the light that matches the polarization direction of the polarizing plate 91 of the liquid crystal panel 90 is incident on the liquid crystal panel 90. At this time, both the light incident on the liquid crystal panel 90 and the reflected light become yellowish light.
  • the light reflected by the brightness increasing film 70 is incident on the LED substrate 10, is reflected, and is incident on the wavelength conversion sheet 50. As a result, a part of the blue light contained in the incident light is further converted into green light and red light, so that the light emitted from the wavelength conversion sheet 50 becomes more yellowish light.
  • the light emitted from the blue LED 11 moves away from the position directly above the blue LED 11, and separates from the position directly above the blue LED 11.
  • the light incident on the liquid crystal panel 90 becomes stronger and yellowish. Therefore, there is a problem that the image displayed on the liquid crystal panel 90 becomes more yellowish as the distance from the position directly above the lit blue LED 11 increases.
  • Patent Document 1 discloses a liquid crystal display device in which a dichroic film 40 is added between the first diffusion plate 20 of the backlight 280 and the wavelength conversion sheet 50 in order to solve the above problem.
  • FIG. 13 is a diagram showing a transmission path of blue light emitted when only one blue LED 11 is turned on in a liquid crystal display device in which a dichroic film 40 is added to the liquid crystal display device shown in FIG.
  • the dichroic film 40 is a film that transmits only light having a specific wavelength (blue light) and does not transmit light having other wavelengths (red light and green light).
  • the effect of adding the dichroic film 40 was examined with the distance OD between the LED substrate 10 of the backlight 280 and the first diffusion plate 20 being 20 mm.
  • a part of the blue light emitted from the blue LED 11 and the red light and the green light converted from the blue light by the wavelength conversion sheet 50 are incident on the brightness increasing film 70.
  • the brightness increasing film 70 transmits blue light and yellow light that match the polarization direction of the polarizing plate 91 arranged on the back surface side of the liquid crystal panel 90, and reflects blue light and yellow light having other polarization directions for recycling. do.
  • the blue light passes through the dichroic film 40, enters the LED substrate 10, and is reflected.
  • the yellow light is reflected by the dichroic film 40, it cannot propagate to the space sandwiched between the first diffusion plate 20 and the LED substrate 10.
  • FIG. 14A is a diagram showing the difference in color unevenness in the x direction of the image displayed on the liquid crystal display device depending on the presence or absence of the dichroic film 40
  • FIG. 14B is displayed on the liquid crystal display device depending on the presence or absence of the dichroic film 40. It is a figure which shows the difference in the color unevenness in the y direction of the image.
  • the horizontal axes of FIGS. 14A and 14B represent the distances from the position of the blue LED 11 in the x-direction or the y-direction, respectively, and the vertical axis represents the chromaticity of the image displayed on the liquid crystal panel 90 in the x-direction or y-direction. Represents.
  • the dichroic film 40 By adding the dichroic film 40 to the direct type backlight 280, it was possible to suppress the occurrence of color unevenness in and around the position directly above the lit blue LED 11. However, in order to make the liquid crystal display device thinner, it is necessary to make the interval OD of the backlight 280 narrower. Therefore, a case where the distance OD between the LED substrate 10 and the first diffusion plate 20 is narrowed to 10 mm was examined.
  • FIG. 15A is a diagram showing the difference in color unevenness in the x direction of the image displayed on the liquid crystal display device when the distance OD between the LED substrate 10 of the backlight 280 and the first diffusion plate 20 is narrowed
  • FIG. 15B is a diagram showing a difference in color unevenness in the y direction of an image displayed on a liquid crystal display device when the distance OD between the LED substrate 10 of the backlight 280 and the first diffusion plate 20 is narrowed.
  • FIGS. 15A and 15B when the interval OD was set to 10 mm, the chromaticity dent became larger in the vicinity of the position directly above the blue LED 11 as compared with the case shown in FIGS. 14A and 14B.
  • the liquid crystal display device is A liquid crystal display device including a direct-type backlight that emits backlight light and a liquid crystal display that displays an image by transmitting the backlight light.
  • the direct type backlight is A light source mounting board with multiple blue light sources that emit blue light, A wavelength-selective transmissive reflective layer that is arranged on the light source mounting substrate, transmits the blue light, and reflects red light and green light. It includes a wavelength conversion layer that converts a part of the blue light transmitted through the wavelength selective transmission reflection layer into red light and green light and transmits the remaining blue light as it is, and transmits the remaining blue light as it is. Further provided is a diffusion means arranged between the light source mounting substrate and the wavelength selective transmission / reflection layer in order to diffuse the blue light emitted from the blue light source.
  • the blue light emitted from the blue light source is further diffused by the diffusing means. Therefore, the blue light spreads widely in a circle around the position directly above the blue light source. As a result, the intensity of blue light incident directly above the blue light source is reduced, so even if the distance between the light source mounting substrate and the diffuser is narrowed, the color unevenness that appears directly above each blue light source becomes a problem visually. It can be reduced to a level that does not become.
  • FIG. 4 is a plan view of a second diffusion plate of the liquid crystal display device shown in FIG.
  • FIG. 4 is a cross-sectional view of a cut surface when the second diffusion plate is cut along the cutting lines II-II shown in the plan view. It is a figure which shows the path from the hollow of the 2nd diffusing plate to the blue light incident on the 2nd diffusing plate of the liquid crystal display device shown in FIG. In the liquid crystal display device shown in FIG. 4, it is a figure which shows the path from the blue LED to the blue light which was incident on the depression of the 2nd diffuser plate, is incident on the liquid crystal panel. It is sectional drawing which shows the structure of the liquid crystal display device which concerns on 3rd Embodiment of this invention. FIG.
  • FIG. 8 is a diagram showing a path from the blue LED to the blue light incident on the second diffuser plate incident on the liquid crystal panel in the liquid crystal display device shown in FIG. 7. It is sectional drawing which shows the structure of the liquid crystal display device which concerns on 4th Embodiment of this invention. It is a figure which shows the transmission path of blue light which passes through a diffusing lens in the liquid crystal display device shown in FIG. 9 is a diagram showing color unevenness in the x direction of an image displayed on the liquid crystal display device due to the provision of a diffusion lens in the liquid crystal display device shown in FIG. 9. 9 is a diagram showing color unevenness in the y direction of an image displayed on the liquid crystal display device due to the provision of a diffusion lens in the liquid crystal display device shown in FIG. 9.
  • FIG. 3 is a diagram showing a difference in color unevenness in the x direction of an image displayed on the liquid crystal display device depending on the presence or absence of a dichroic film in the liquid crystal display device shown in FIG.
  • FIG. 3 is a diagram showing a difference in color unevenness in the y direction of an image displayed on the liquid crystal display device depending on the presence or absence of a dichroic film in the liquid crystal display device shown in FIG.
  • FIG. 1 is a cross-sectional view showing the configuration of a liquid crystal display device according to the first embodiment of the present invention.
  • the backlight 81 of the liquid crystal display device is an LED substrate 10 (also referred to as a “blue light source”) on which blue LEDs 11 (also referred to as “blue light sources”) are spread, similar to the liquid crystal display device shown in FIG. 13 described in the background art.
  • a second diffuser plate 31 having a diffusion function for diffusing the blue light emitted from the blue LED 11, a first diffuser plate 20 for further diffusing the blue light, and a blue light are transmitted.
  • a dichroic film 40 that reflects red light and green light also referred to as a "wavelength selective transmission reflection layer”
  • a wavelength conversion sheet 50 that converts a part of blue light into red light and green light
  • An optical sheet 60 in which a prism or a microlens is arranged on the sheet to improve the front brightness, and blue light and yellow light that match the polarization direction of the polarizing plate 91 provided on the back surface side of the liquid crystal panel 90 are transmitted.
  • the brightness increasing film 70 also referred to as “optical recycling layer” that reflects and recycles other blue light and yellow light is laminated in this order.
  • a liquid crystal panel 90 provided with a polarizing plate 91 is arranged on the backlight 81. Therefore, the white light composed of the blue light and the yellow light emitted from the backlight 81 passes through the liquid crystal panel 90, so that the viewer can visually recognize the image of the color corresponding to the image signal.
  • the wavelength conversion sheet 50 constituting the backlight 81 includes a red fluorescent sheet (not shown) coated with a phosphor that emits red light when blue light is incident, and a green fluorescent sheet coated with a phosphor that emits green light (not shown). (Not shown) and included. Therefore, when the blue light emitted from the blue LED 11 is incident on the wavelength conversion sheet 50, the wavelength conversion sheet 50 converts a part of the blue light into red light and green light, together with the blue light that is not converted into either. Eject.
  • a green quantum dot (Quantum dot: QD) that emits green light and a red quantum dot that emits red light are combined.
  • QD quantum dot
  • a quantum dot layer (also referred to as a "QD sheet") may be provided.
  • QD sheet since the green light and red light emitted by each quantum dot of the quantum dot sheet have a narrow half-price range, the color gamut of the liquid crystal display should be widened by combining with the high-density color film formed on the liquid crystal panel 90. Can be done.
  • the dichroic film 40 transmits blue light, is reflected by the brightness increasing film 70, and reflects recycled red light and green light.
  • the dichroic film 40 that can be used in this embodiment and each of the embodiments described later includes, for example, a BLT (Blue Light Transmitting) film manufactured by Three M.
  • the dichroic film 40 As described in the background art, by providing the dichroic film 40, the light emitted from the backlight 81 does not become yellowish, so that the image displayed at a position away from the position directly above the lit blue LED 11 is displayed. It never turns yellow.
  • the brightness increasing film 70 transmits the incident blue light, red light, and green light having the same polarization direction as the polarizing plate 91 on the back surface side of the liquid crystal panel 90, and can reflect and transmit other light. Recycle to convert to light. As a result, in the end, almost all the light emitted from the blue LED 11 is incident on the liquid crystal panel 90, so that the screen of the liquid crystal panel 90 is brightened. Moreover, since the utilization efficiency of blue light can be increased, the power consumption of the liquid crystal display device can be reduced.
  • the brightness increasing film 70 that can be used in this embodiment and each of the embodiments described later includes, for example, a DBEF (Dual Brightness Enhancement Film) film manufactured by Three M.
  • the optical sheet 60 has a function of arranging a prism or a microlens on the sheet to improve the front luminance.
  • the light transmitted through the wavelength conversion sheet 50 is reflected by the brightness increasing film 70, but in reality, a part of the light is also reflected by the optical sheet 60.
  • a second diffuser plate 31 is added between them.
  • an ink body 311 made of ink having a function of diffusing blue light is placed directly above each blue LED on a plate (also referred to as a “transparent substrate”) made of a transparent material such as acrylic resin. They are arranged one by one.
  • the ink body 311 is formed by printing an ink containing a filler for diffusing light, a binder for fixing to the plate, and a solvent on the plate by, for example, screen printing, and drying the ink.
  • the ink body 311 may be formed by using an ink having light resistance so that the deterioration of the diffusing function can be delayed even if the blue light is irradiated for a long time.
  • the solder resist used when mounting the blue LED 11 on the LED substrate 10 has a low reflectance. Therefore, even if the blue light reflected by the brightness increasing film 70 passes through the dichroic film 40 and enters the LED substrate 10, there is a problem that the amount of blue light reflected by the LED substrate 10 is reduced.
  • FIG. 2 is a diagram showing a reflective sheet 12 provided on the LED substrate 10.
  • 2 is a plan view of the LED substrate 10 shown in FIG. 2, and a cross-sectional view of a cut surface when the LED substrate 10 is cut along the cutting lines II-II shown in the plan view.
  • the reflective sheet 12 has an opening at a position where the blue LED 11 is mounted, and is formed so as to surround the blue LED 11.
  • the description of the reflective sheet 12 is omitted.
  • this embodiment aims to solve a problem caused by narrowing the distance between the upper surface of the blue LED 11 mounted on the LED substrate 10 and the first diffusion plate 20.
  • the thickness of the blue LED 11 is as thin as about 1 to 3 mm, the distance OD between the LED substrate 10 and the first diffusion plate 20 is substantially the same. Therefore, in the present specification, it will be described that the distance OD between the LED substrate 10 and the first diffusion plate 20 is narrowed, not the distance between the upper surface of the blue LED 11 and the first diffusion plate 20.
  • FIG. 3 is a cross-sectional view of a liquid crystal display device showing a path until the blue light emitted from the blue LED 11 enters the liquid crystal panel 90 in the present embodiment.
  • the blue light emitted directly above the blue LED 11 is incident on the ink body 311 of the second diffusion plate 31.
  • the light incident on the ink body 311 is diffused by the ink body 311.
  • the blue light incident on the ink body 311 spreads in a conical shape around the ink body 311 and is emitted, and is incident on the first diffusion plate 20.
  • the blue light is further diffused and spread by the first diffuser plate 20, and a part of the blue light emitted from the adjacent blue LEDs 11 overlaps with each other.
  • the blue light diffused in this way passes through the dichroic film 40 and is incident on the wavelength conversion sheet 50.
  • the wavelength conversion sheet 50 transmits a part of the incident blue light as it is, and converts the remaining blue light into red light and green light. Therefore, in FIG. 3, the light emitted from the wavelength conversion sheet 50 is described as blue light and yellow light composed of red light and green light.
  • Blue light and yellow light pass through the optical sheet 60 and enter the brightness increasing film 70.
  • the brightness increasing film 70 transmits blue light and yellow light in the same polarization direction as the polarizing plate 91 arranged on the back surface side of the liquid crystal panel 90.
  • the blue light and yellow light transmitted through the brightness increasing film 70 pass through the polarizing plate 91 as white light, and further pass through the liquid crystal panel 90. As a result, an image of a color corresponding to the image signal is displayed on the liquid crystal panel 90.
  • the blue light and yellow light reflected by the brightness increasing film 70 pass through the optical sheet 60 and the wavelength conversion sheet 50 for recycling and are incident on the dichroic film 40.
  • the blue light passes through the dichroic film 40, but the red light and the green light constituting the yellow light cannot be transmitted. Therefore, only blue light passes through the first diffuser plate 20 and the second diffuser plate 31, enters the LED substrate 10, and is reflected by the LED substrate 10. Since the transmission path of the reflected blue light is the same as the transmission path of the blue light emitted from the blue LED 11, the description thereof will be omitted. In this case, since the ratio of the amount of light between the blue light and the red light and the green light does not change, the image displayed at a position away from the position directly above the lit blue LED 11 does not turn yellow.
  • the blue light is repeatedly reflected between the LED substrate 10 and the brightness increasing film 70, so that most of the blue light emitted from the blue LED 11 is finally combined with the yellow light whose wavelength is converted from the blue light. It passes through the brightness increasing film 70 and is incident on the liquid crystal panel 90.
  • a liquid crystal display device In recent years, in order to reduce power consumption, a liquid crystal display device has been developed that logically divides the illumination area into a plurality of areas and performs local dimming drive to control the brightness (emission intensity) of the LED for each area. ..
  • local dimming drive the brightness of the light source is controlled according to the image displayed in the corresponding area. Specifically, the brightness of each light source is controlled based on the maximum value or the average value of the target brightness (brightness corresponding to the input gradation value) of the pixels displayed in the corresponding area.
  • HDR High Dynamic Range
  • the backlight 81 described in the present embodiment it is possible to improve the bluish color unevenness at the position directly above each blue LED 11, so that when the local dimming drive or the HDR drive is performed, the yellowish color and the HDR color can be improved. It is possible to suppress the occurrence of bluish color unevenness.
  • the same effect can be obtained by using the backlights 82 to 84 of each embodiment described later instead of the backlight 81.
  • the blue light emitted from each blue LED 11 is diffused not only by the first diffusion plate 20 but also by the second diffusion plate 31 on which the ink body 311 having a diffusion function is formed. Therefore, the blue light spreads widely in a circle around the position directly above the blue LED 11. As a result, the intensity of the blue light incident on the vicinity of the blue LED 11 of the liquid crystal panel 90 can be reduced, so that even if the distance OD between the LED substrate 10 and the first diffusion plate 20 is narrowed to about 10 mm, each The blue color unevenness in the region of the liquid crystal panel 90 directly above the blue LED 11 can be reduced to a level that does not cause a problem visually. Further, by improving the blue color unevenness to a level that cannot be visually confirmed, the backlight 81 can be made thinner, and the liquid crystal display device can be made thinner.
  • the backlight 81 is used, it is possible to further improve the color unevenness at a level that is not noticeable visually.
  • FIG. 4 is a cross-sectional view showing the configuration of the liquid crystal display device according to the second embodiment.
  • the basic configuration of the liquid crystal display device according to the present embodiment is the same as the configuration of the first embodiment, and only the second diffuser plate 32 is the second diffuser plate of the first embodiment. Different from 31. Specifically, in the second diffusion plate 32, a recess 321 is formed directly above the blue LED 11. Therefore, the description of the cross-sectional view showing the structure of the liquid crystal display device will be omitted, and the structure and function of the second diffusion plate 32 will be described.
  • FIG. 5A is a plan view of the second diffusion plate 32 shown in FIG. 4 and a cross-sectional view of the cut surface when the second diffusion plate 32 is cut along the cutting line VV shown in the plan view.
  • the transparent plate (also referred to as “transparent substrate”) constituting the second diffusion plate 32 is provided with a conical recess 321 at a position corresponding to directly above each blue LED 11.
  • the apex of the conical recess 321 is directly above the injection portion of the blue LED 11 and is located on the lower surface of the second diffusion plate 32.
  • the cone is formed so as to extend from the apex to the upper surface of the second diffusion plate 32. Therefore, the area of the bottom surface of the cone is formed to be at least as large as the blue LED 11 so that almost all the blue light emitted from the blue LED 11 is incident on the inside of the conical recess 321.
  • FIG. 5B is a diagram showing a path from the blue light incident on the second diffusion plate 32 to being emitted from the recess 321 of the second diffusion plate 32. It is a figure which shows the path from the blue LED 11 to the emission of the blue light incident on the depression 321 of the second diffusion plate 32.
  • the blue light emitted from the blue LED 11 enters the second diffusion plate 32, it travels straight through the second diffusion plate 32 and is emitted into the depression 321 from the side surface of the depression 321.
  • the blue light travels from the second diffuser plate 32 having a large refractive index into the air having a small refractive index, it is refracted according to Snell's law.
  • the blue light emitted from the second diffusion plate 32 into the recess proceeds so as to approach the slope of the cone, that is, to spread.
  • the blue light diffused by the second diffuser 32 is further diffused and spread by the first diffuser 20.
  • FIG. 6 is a diagram showing a path from the blue LED 11 to the blue light incident on the recess 321 of the second diffusion plate 32 entering the liquid crystal panel 90 in the liquid crystal display device shown in FIG.
  • the blue light emitted from the blue LED 11 is diffused so as to spread by incident on the recess 321 of the second diffuser plate 32.
  • each layer from the dichroic film 40 to the brightness increasing film 70 is transmitted and incident on the liquid crystal panel 90.
  • the slope of the cone is a slope that slopes linearly from the apex to the outside.
  • the slope of the recess 321 does not necessarily have to be straight, and may extend in a curved shape from a position directly above the blue LED 11 toward the outside.
  • the present embodiment when the light emitted from the blue LED 11 enters the conical recess 321 formed in the second diffusion plate 32 formed directly above the blue LED 11, it spreads along the slope of the cone. It is diffused. As a result, the intensity of the blue light incident on the vicinity of the position directly above the blue LED 11 is reduced, so that there is no problem visually even if the distance OD between the LED substrate 10 and the first diffusion plate 20 is narrowed to about 10 mm. Blue color unevenness can be reduced to the level. Further, by improving the blue color unevenness to an invisible level, the backlight 82 can be made thinner, and the liquid crystal display device can be made thinner.
  • the interval OD is narrow but also when the interval OD is sufficiently wide as 20 mm, as in the case of the first embodiment, if the backlight 82 is used, the color unevenness at a level that is not visually noticeable is further improved. be able to.
  • FIG. 7 is a cross-sectional view showing the configuration of the liquid crystal display device according to the third embodiment.
  • the basic configuration of the liquid crystal display device according to the present embodiment is the same as the configuration of the first embodiment, and only the second diffusion plate 33 is the second diffusion plate of the first embodiment. Different from 31. Therefore, the description of the cross-sectional view showing the structure of the liquid crystal display device will be omitted, and the structure and function of the second diffusion plate 33 will be described.
  • the second diffusion plate 33 included in the liquid crystal display device according to the present embodiment is at least one of the upper surface and the lower surface of the transparent plate 331 (also referred to as “transparent substrate”) made of acrylic resin or the like, like the first diffusion plate 20.
  • Crab for example, a diffusion layer 332 containing microlenses in a completely random state is formed. Since the diffusion layer 332 diffuses the blue light transmitted through the transparent plate 331 or the blue light before being incident on the transparent plate 331, the blue light emitted from the second diffusion plate 33 spreads. As a result, by weakening the intensity of the blue light in the region of the liquid crystal panel 90 directly above the blue LED 11, the color unevenness of the displayed image can be reduced to a level at which it does not visually turn blue.
  • the second diffusion plate 33 includes not only the one in which the diffusion layer 332 is provided on the upper surface or the lower surface of the transparent plate 331 as described above, but also the transparent plate 331 having a diffusion effect such as air bubbles and beads. The ones that have been made are also included.
  • FIG. 8 is a diagram showing a path from the blue LED 11 to the blue light incident on the second diffusion plate 33 on the liquid crystal panel 90 in the liquid crystal display device shown in FIG.
  • the blue light emitted from the blue LED 11 enters the second diffusion plate 33 and is diffused so as to be spread by the diffusion layer 332 provided on the surface of the second diffusion plate 33.
  • each layer from the dichroic film 40 to the brightness increasing film 70 is transmitted and incident on the liquid crystal panel 90.
  • the second diffuser plate 33 is arranged between the LED substrate 10 and the first diffuser plate 20, it is preferable to arrange the second diffuser plate 33 closer to the LED substrate 10. By arranging the second diffuser 33 near the LED substrate 10 in this way, the blue light diffused by the second diffuser 33 is incident on the first diffuser 20 in a sufficiently spread state. This is because the blue light is more diffused by the first diffusing plate 20.
  • the blue light emitted from the blue LED 11 is diffused by the second diffuser plate 33 so as to spread outward from the position immediately above the blue LED 11, and is further diffused by the first diffuser plate 20.
  • the intensity of blue light incident on the region near the position of the liquid crystal panel 90 directly above the blue LED 11 can be reduced, so that the distance OD between the LED substrate 10 and the first diffuser plate 20 is narrowed to about 10 mm.
  • the color unevenness that turns blue in the region of the liquid crystal panel 90 directly above each blue LED 11, which has been a problem in the past, is visually reduced to a level that does not cause a problem.
  • FIG. 9 is a cross-sectional view showing the configuration of the liquid crystal display device according to the fourth embodiment. As shown in FIG. 9, in the backlight 84 of the liquid crystal display device according to the present embodiment, diffusion for diffusing the blue light emitted from the blue LED 11 on the upper surface of each blue LED 11 mounted on the LED substrate 10. A lens 34 is provided.
  • FIG. 10 is a diagram showing a transmission path of blue light transmitted through the diffusion lens 34.
  • the diffusion lens 34 formed so as to cover the blue LED 11 is made of a transparent resin such as acrylic, and a recess 341 is formed on the surface near the upper surface of the blue LED 11. Therefore, the diffuser lens 34 of the present embodiment is a concave lens.
  • the blue light incident on the diffuser lens 34 is refracted at a refraction angle larger than the incident angle and is emitted so as to spread toward the first diffusion plate 20 as in the case described in the second embodiment. NS. Next, the blue light incident on the first diffusion plate 20 is further diffused and spread.
  • FIG. 11A is a diagram showing color unevenness in the x direction of the image displayed on the liquid crystal display device due to the provision of the diffuser lens 34
  • FIG. 11B is a diagram showing color unevenness in the x direction due to the provision of the diffuser lens 34. It is a figure which shows the color unevenness in the y direction of the displayed image.
  • the horizontal axes of FIGS. 11A and 11B represent the distances from the position of the blue LED 11 in the x-direction or the y-direction, respectively, and the vertical axis represents the chromaticity of the image displayed on the liquid crystal panel 90 in the x-direction or y-direction. Represents.
  • the chromaticity is dented at the position directly above the blue LED 11, so that the color is displayed in the region of the liquid crystal panel 90 directly above the blue LED 11. It indicates that unevenness has occurred.
  • the diffuser lens 34 on the surface of the blue LED 11, the dent in chromaticity is almost eliminated, and the dent is reduced to a level that causes almost no problem visually.
  • the diffusing lens 34 by forming the diffusing lens 34 on the upper surface of the blue LED 11, the blue light emitted from the blue LED 11 is spread by the diffusing lens 34, and then further incident on the first diffusing plate 20. spread. As a result, the intensity of blue light at a position directly above the blue LED 11 is reduced. Therefore, even if the distance OD between the LED substrate 10 and the first diffusion plate 20 is narrowed to about 10 mm, each blue color has been a problem in the past. The blue color unevenness in the region of the liquid crystal panel 90 directly above the LED 11 is visually reduced to a level at which there is no problem.
  • the dichroic film 40 is wavelength-converted to the first diffuser plate 20 without providing the second diffuser plates 31 to 33 or the diffuser lens 34. Color unevenness could be reduced only by providing it between the sheet 50 and the sheet 50, but as shown in FIGS. 14A and 14B, some dents in chromaticity remain.
  • the backlights 81 to 84 of each of the above embodiments include the reflective sheet 12, the first diffusion plate 20, the optical sheet 60, and the brightness increasing film 70.
  • diffusing means the second diffusing plates 31 to 33 described in each of the first to third embodiments and the diffusing lens 34 of the fourth embodiment may be collectively referred to as "diffusing means".
  • LED board (light source mounting board) 11 ... Blue LED (blue light source) 20 ... 1st diffusion plate 31-33 ... 2nd diffusion plate (diffusion member) 34 ... Diffusing lens (diffusing member) 40 ... Dichroic film (wavelength selective transmission / reflection layer) 50 ... Wavelength conversion sheet (wavelength conversion layer) 60 ... Optical sheet 70 ... Brightness increasing film (optical recycling layer) 81-84 ... Direct backlight 90 ... Liquid crystal panel 91 ... Polarizing plate

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  • Optics & Photonics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Nonlinear Science (AREA)
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Abstract

La présente invention met en œuvre un dispositif d'affichage à cristaux liquides capable de supprimer l'apparition d'une couleur irrégulière teintée avec du bleu à une position immédiatement au-dessus d'une DEL bleue éclairée même lorsqu'un espace entre un substrat de DEL et une plaque de diffusion est rétréci afin de réduire l'épaisseur d'un rétroéclairage de type direct.　Ce dispositif d'affichage à cristaux liquides diffuse la lumière bleue émise par une source de lumière bleue en fournissant une plaque de diffusion obtenue par formation d'un corps d'encre sur un substrat transparent entre un substrat de DEL et un film dichroïque d'un rétroéclairage de type direct. Par conséquent, l'intensité de la lumière bleue incidente dans le voisinage d'une zone immédiatement au-dessus de la source de lumière bleue est réduite, ce qui permet de réduire la couleur bleue irrégulière apparaissant immédiatement au-dessus de chaque source de lumière bleue à un niveau visuellement non problématique même lorsqu'un espace entre un substrat équipé d'une source de lumière et la plaque de diffusion est rétréci.
PCT/JP2020/043786 2020-01-24 2020-11-25 Dispositif d'affichage à cristaux liquides WO2021149347A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010062305A (ja) * 2008-09-03 2010-03-18 Hitachi Displays Ltd 照明装置、及び液晶表示装置
JP2010164744A (ja) * 2009-01-15 2010-07-29 Oji Paper Co Ltd 輝度均斉化シートおよび面光源装置
CN208027043U (zh) * 2017-11-30 2018-10-30 3M创新有限公司 直下式背光源及液晶显示器
JP2018206598A (ja) * 2017-06-02 2018-12-27 スリーエム イノベイティブ プロパティズ カンパニー 直下型バックライト
WO2019138722A1 (fr) * 2018-01-12 2019-07-18 富士フイルム株式会社 Unité de rétroéclairage et écran à cristaux liquides

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010062305A (ja) * 2008-09-03 2010-03-18 Hitachi Displays Ltd 照明装置、及び液晶表示装置
JP2010164744A (ja) * 2009-01-15 2010-07-29 Oji Paper Co Ltd 輝度均斉化シートおよび面光源装置
JP2018206598A (ja) * 2017-06-02 2018-12-27 スリーエム イノベイティブ プロパティズ カンパニー 直下型バックライト
CN208027043U (zh) * 2017-11-30 2018-10-30 3M创新有限公司 直下式背光源及液晶显示器
WO2019138722A1 (fr) * 2018-01-12 2019-07-18 富士フイルム株式会社 Unité de rétroéclairage et écran à cristaux liquides

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