WO2018161650A1 - 显示面板和显示装置 - Google Patents

显示面板和显示装置 Download PDF

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Publication number
WO2018161650A1
WO2018161650A1 PCT/CN2017/114240 CN2017114240W WO2018161650A1 WO 2018161650 A1 WO2018161650 A1 WO 2018161650A1 CN 2017114240 W CN2017114240 W CN 2017114240W WO 2018161650 A1 WO2018161650 A1 WO 2018161650A1
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WIPO (PCT)
Prior art keywords
layer
grating
optical waveguide
substrate
fluid
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PCT/CN2017/114240
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English (en)
French (fr)
Inventor
孟宪芹
王维
董学
杨亚锋
陈小川
谭纪风
孟宪东
高健
Original Assignee
京东方科技集团股份有限公司
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Application filed by 京东方科技集团股份有限公司 filed Critical 京东方科技集团股份有限公司
Priority to US16/067,980 priority Critical patent/US10718936B2/en
Publication of WO2018161650A1 publication Critical patent/WO2018161650A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/004—Optical devices or arrangements for the control of light using movable or deformable optical elements based on a displacement or a deformation of a fluid
    • G02B26/005—Optical devices or arrangements for the control of light using movable or deformable optical elements based on a displacement or a deformation of a fluid based on electrowetting
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1814—Diffraction gratings structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1866—Transmission gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B2207/00—Coding scheme for general features or characteristics of optical elements and systems of subclass G02B, but not including elements and systems which would be classified in G02B6/00 and subgroups
    • G02B2207/115—Electrowetting

Definitions

  • Embodiments of the present disclosure relate to a display panel and a display device including the same.
  • a conventional LCD device includes a backlight and a display panel.
  • the display panel includes an array substrate and a color filter substrate disposed opposite to each other, and a liquid crystal layer is disposed between the array substrate and the color filter substrate, and the back surface of the array substrate and the back surface of the color filter substrate are disposed.
  • polarizers With polarizers, the transmittance of the display panel and the spectrum of the transmission are greatly affected by the functional layers such as the polarizer and the color filter layer.
  • conventional LCD and OLED are difficult to achieve high PPI, and subject to the outgoing light as divergent light, conventional LCD and OLED are difficult to achieve near-eye display with monocular focus.
  • At least one embodiment of the present disclosure provides a display panel including an optical waveguide layer and a first substrate disposed opposite to each other, and an electrowetting control layer disposed between the optical waveguide layer and the first substrate,
  • the electrowetting control layer includes a first electrode layer, a second electrode layer, and a grating layer and an electrowetting layer disposed between the first electrode layer and the second electrode layer, the grating layer and the electrowetting layer configuration
  • Light rays of a set transmittance, a set direction, and a set wavelength are coupled out from the optical waveguide layer.
  • the first electrode layer is disposed on a side of the optical waveguide layer adjacent to the first substrate, and the second electrode layer is disposed on a side of the first substrate near the optical waveguide layer.
  • the grating layer is disposed on the first electrode layer, and the electrowetting layer is disposed on the grating layer.
  • the electrowetting layer includes a first fluid and a second fluid,
  • the difference between the refractive index of the first fluid and the refractive index of the grating layer is less than or equal to 0.05, and the difference between the refractive index of the second fluid and the refractive index of the grating layer is greater than or equal to 0.1.
  • the first fluid is an aqueous fluid having conductive properties
  • the second fluid is an oily fluid having insulating properties
  • the first fluid is an aqueous fluid having insulating properties
  • the second fluid is an oily fluid having electrically conductive properties.
  • one or more sides of the optical waveguide layer are used for incident collimating backlight, and a grating grating coupler is formed with the grating layer, and a refractive index of the optical waveguide layer is greater than the first The refractive index of an electrode layer and the grating layer.
  • the display panel further includes a second substrate, the optical waveguide layer is disposed on the second substrate, or the optical waveguide layer and the second substrate are integrated.
  • the grating layer is a one-dimensional grating
  • the one-dimensional grating includes a plurality of grating strips arranged in the same direction
  • the one-dimensional grating is prepared by using a transparent dielectric material and has a thickness of 100 nm to 1000 nm.
  • the duty ratio is 0.1 to 0.9.
  • the grating layer is a two-dimensional grating
  • the two-dimensional grating comprises a plurality of grating blocks arranged in an array
  • the two-dimensional grating is prepared by using a transparent dielectric material and has a thickness of 100 nm to 1000 nm.
  • the duty ratio is 0.1 to 0.9.
  • the display panel further includes a first protective film and/or a second protective film, the first protective film being disposed on a surface of the optical waveguide layer away from the first substrate, the first The second protective film is disposed on a surface of the first substrate away from the side of the optical waveguide layer.
  • the grating layer is a nano grating layer or a micro grating layer.
  • At least one embodiment of the present disclosure also provides a display device including the above display panel.
  • the display device further includes a side-entry collimating backlight, and the side-entry collimating backlight that generates the collimated backlight is disposed on one or more sides of the display panel.
  • Embodiments of the present disclosure provide a display panel and a display device provided with an electrowetting layer based on an electrowetting technique and a grating layer based on a waveguide grating coupling technique, and the color of the light is selected through the grating layer, thereby realizing the use of a color film.
  • the color display shows that the light direction is controlled by the grating layer, the polarizer is omitted, and the transparent layer is used for each functional layer, thereby realizing high transmittance display. Since the grating layer can couple the light in the range of the grating period of the micrometer or nanometer scale, the size of the pixel area can be made small, thereby realizing a high PPI display.
  • the combination of the electrowetting layer and the grating layer not only realizes a variable refractive index grating and a grating switch, but also achieves no viewing angle range limitation and fast response. Pass Through the control of the light exiting direction, the emitted light is concentrated to the pupil position, which can realize near-eye display and meet the requirements of VR/AR. By using a thicker optical waveguide layer, it has higher light utilization efficiency, improves screen brightness, and reduces power consumption.
  • FIG. 1 is a schematic structural view of a display panel according to an embodiment of the present disclosure
  • Figure 2 is a schematic view of the principle of electrowetting
  • FIG. 3 is a schematic diagram of a basic model based on electrowetting display
  • FIG. 4 is a schematic diagram of the operation of a waveguide grating coupler in accordance with an embodiment of the present disclosure
  • 5 to 7 are schematic diagrams showing a gray scale display of a display panel according to a first embodiment of the present disclosure
  • FIG. 8 is a schematic structural view of a one-dimensional grating according to a first embodiment of the present disclosure
  • FIG. 9 is a light emission spectrum diagram of a one-dimensional grating according to a first embodiment of the present disclosure.
  • FIGS. 10 to 11 are structural diagrams of a two-dimensional grating according to a first embodiment of the present disclosure
  • FIG. 12 is a light emission spectrum diagram of a two-dimensional grating according to a first embodiment of the present disclosure.
  • 1 conductive droplets
  • 2 substrate
  • 3 electrode
  • 4 the first medium drop
  • 5 second medium
  • 10 an optical waveguide layer
  • 20 the first substrate
  • 30 electrowetting control layer
  • 31 first electrode layer
  • 33 the electrowetting layer
  • 34-second electrode layer 331 - the first fluid
  • 333 aqueous fluid
  • 334 - oily fluid
  • FIG. 1 is a schematic structural view of a display panel according to an embodiment of the present disclosure.
  • the main structure of the display panel of the embodiment of the present invention includes an optical waveguide layer 10 and a first substrate 20 disposed opposite to each other, and an electrowetting control layer 30 disposed between the optical waveguide layer 10 and the first substrate 20 .
  • One or more sides of the optical waveguide layer 10 are used for incident collimating backlights, and the electrowetting control layer 30 is configured to couple light in the optical waveguide layer 10 to set a transmittance, a set direction, and a set wavelength of light.
  • the electrowetting control layer 30 is configured to set the display gradation (set transmittance) of each pixel region, set the light exit direction (set direction) of each pixel region, and set the light output color of each pixel region (setting Wavelength), in which light of a specific color is emitted from a specific direction in a specific direction in each pixel region.
  • three pixel regions may be disposed to form one pixel, and the display gradation of three pixel regions is set by the electrowetting control layer 30, and the color of the three pixel regions is set to be red light R, green light G, and blue light B, respectively.
  • the light-emitting direction of each pixel area is set to be the middle of the pixel area, achieving high transmittance, high resolution, and near-eye display.
  • the left side surface of the optical waveguide layer is configured as an incident collimated backlight, and of course, a plurality of side surfaces of the optical waveguide layer (for example, a right side surface opposite to the left side surface, a front side not shown in the drawing) And the back side) can be configured as an incident collimated backlight.
  • the collimated backlight is incident at a greater than or equal to a critical angle, and multiple total reflection occurs during transmission in the optical waveguide layer to ensure long-distance transmission of light in the optical waveguide layer, and multiple oscillation coupling with the electrowetting control layer to a specific color Light is coupled out of the optical waveguide layer in a particular direction (details will be explained below).
  • the optical waveguide layer can be used as the second substrate, that is, the second substrate and the optical waveguide layer are integrated, or the second substrate can be separately disposed, the optical waveguide layer is disposed on the second substrate, and the second substrate and the first substrate are passed through.
  • the sealant is packaged in a box and the electrowetting control layer is encapsulated in a box.
  • the display panel may further include a first protective film disposed on a side surface of the first substrate facing away from the optical waveguide layer/second substrate, and a surface disposed on a side of the optical waveguide layer/second substrate facing away from the first substrate
  • the second protective film, the first protective film and the second protective film are configured to protect the display panel.
  • the first protective film and the second protective film may be a film layer attached to the surface, or may be a coating layer coated on the surface.
  • Electrowetting control layer 30 is an light extraction control layer based on electrowetting technology. As shown in FIG. 1, the electrowetting control layer 30 includes a first electrode layer 31, a grating layer 32, an electrowetting layer 33, and a second electrode layer 34, wherein the grating layer 32 is disposed on the first electrode layer 31.
  • the electrowetting layer 33 is disposed on the grating layer On the 32, the second electrode layer 34 is disposed on the electrowetting layer 33.
  • the electrowetting control layer 33 is interposed between the optical waveguide layer 10 and the first substrate 20, the first electrode layer 31 is disposed adjacent to the optical waveguide layer 10, and the second electrode layer 34 is disposed adjacent to the first substrate 20.
  • the optical waveguide layer 10 and the grating layer 32 form a waveguide grating coupler that enables selection of the light exiting direction and the color of the outgoing light, i.e., the waveguide grating coupler couples light of a particular wavelength out in a particular direction (this will be described below).
  • the first electrode layer 31 and the second electrode layer 34 are used to apply a voltage to the electrowetting layer 33, and the grating layer 32 and the electrowetting layer 33 are controlled to realize variable waveguide grating coupling and grating switching by the applied voltage intensity, and the light is controlled.
  • the transmittance is achieved to achieve gray scale display.
  • the electrowetting layer 33 includes a first fluid 331 having conductive properties and a second fluid 332 having insulating properties, or a first fluid 331 having insulating properties and a second fluid 332 having conductive properties by changing the first electrode layer 31 and the second electrode layer 34 apply a voltage on the conductive droplets, changing the contact angle of the conductive droplets with the grating layer, so that the first fluid 331 and the second fluid 332 cover the grating layer 32 to different degrees, thereby realizing the variable waveguide grating Coupling effect and grating switch for gray scale display.
  • the first electrode layer 31 may be disposed in contact with the surface of the optical waveguide layer 10, or may be disposed in contact with other functional film layers disposed on the optical waveguide layer 10; the second electrode layer 34 may be disposed in contact with the surface of the first substrate 20. It may also be disposed in contact with other functional film layers disposed on the first substrate 20.
  • the grating layer may be a micro grating layer or a nano grating layer.
  • Electrowetting (EW) display technology is the electrowetting of droplets on a medium.
  • the electrowetting phenomenon of a droplet on a medium refers to changing the wettability of the droplet on the medium by changing the voltage applied to the droplet on the medium, ie changing the contact angle ⁇ of the droplet with the medium, so that The droplets are deformed and displaced.
  • Figure 2 is a schematic illustration of the principle of electrowetting, illustrating the change in contact angle of the droplets with the medium before and after application of the voltage. As shown in FIG.
  • electrowetting technology Since Lippman discovered electrowetting in 1875, electrowetting technology has received widespread attention.
  • the main research and applications include the application of electrowetting technology to reflective, transmissive displays, convertible optical concave/convex Microfluidic lenses, fiber optic communication converters, and biomedical chips.
  • electrowetting technology As a new generation of display technology has received extensive attention, and display models based on electrowetting technology have also been proposed.
  • FIG. 3 is a schematic diagram of a basic model based on electrowetting display.
  • V voltage
  • the dyed first dielectric droplet 4 wets the entire surface of the substrate 2, at which time the light cannot be
  • the dyed first medium droplet 4 passes through, displaying a dark state.
  • the contact angle of the first dielectric droplet 4 with the substrate 2 changes due to the electrowetting effect, shrinks into a small droplet and moves to the end side, and the transparent second medium 5 is covered.
  • the substrate 2, the light can pass through the transparent second medium 5, and the light state is displayed at this time.
  • the contact angle of the first dielectric droplet 4 with the substrate 2 is adjusted such that the area of the area occupied by the first dielectric droplet 4 on the substrate 2 is different, so that the transparent second medium 5 is occupied on the substrate 2.
  • the area change of the area can display different gradations and realize gray scale display.
  • the main difference between electrowetting display technology and liquid crystal display technology is that since electrowetting technology dynamically changes the wavelength and brightness of reflected or transmitted light by changing the surface area of the liquid, it does not need to use polarizing plates, no polarization, no viewing angle. Range limit.
  • the electrowetting phenomenon of the first dielectric droplet 4 on the substrate 2 is faster than the speed of the liquid crystal in response to the voltage rotation, the response of the display device based on the electrowetting technique is fast.
  • the basic principle of the waveguide grating coupler is that the incident light excites the m-th order guided mode in the waveguide to realize the selection of the outgoing light direction and the outgoing light color.
  • 4 is a schematic diagram showing the operation of a waveguide grating coupler according to an embodiment of the present invention. After the collimated backlight is incident on one or more sides of the optical waveguide layer, when the collimated backlight has an angle with the surface of the optical waveguide layer, and the angle is greater than the critical angle, the collimated backlight entering the optical waveguide layer will occur. Total reflection, producing a m-order guided mode.
  • the selection of the light exiting direction and the color of the light exiting can be achieved by coupling the grating layer to a specific mode in the optical waveguide layer, that is, the waveguide grating coupler couples light of a specific wavelength (color) in a specific direction.
  • the waveguide grating coupler couples light of a specific wavelength (color) in a specific direction.
  • n i and ⁇ i are the incident space refractive index and the incident angle, respectively, m is the diffraction order, ⁇ is the grating period, ⁇ is the incident light wavelength, and ⁇ d is the light exit direction, that is, the direction of the diffracted light and the plane normal of the display panel
  • n d is the equivalent refractive index of the electrowetting layer, the second electrode and the first substrate (which can be averaged directly).
  • the light-emitting direction can be precisely designed by professional optical simulation software.
  • the light-emitting direction of a pixel area at a certain position on the display panel is often fixed, and is determined by the position of the pixel area relative to the human eye, that is, the light-emitting direction ⁇ d of the display mode in the above formula. It is fixed.
  • the grating period ⁇ by adjusting the grating period ⁇ , light of a given color (a given wavelength ⁇ ) can be emitted in the light exiting direction ⁇ d . As shown in FIG.
  • the white incident light is coupled to the R, G, and B light beams through the grating layer, and the light outgoing direction of the R color light is directed to the R pixel region, the light emitting direction of the G color light is directed to the G pixel region, and the light emitting direction of the B color light is directed to the B.
  • the pixel area light of a specific color is emitted from each pixel area in a specific direction.
  • a variable refractive index grating and a grating switch are realized by selecting a suitable grating layer material, an electrode material, and an electrowetting layer material by adjusting the voltage applied to the electrowetting layer to change the contact angle of the conductive droplets.
  • the type of color is not limited to three colors of R, G, and B, and may be four colors of R, G, B, and W (white), or may be other three colors.
  • the grating period ⁇ is several micrometers or several hundred nanometers, and the light can be effectively coupled from the waveguide layer, and the grating period corresponding to each pixel region is generally small, so each The size of the pixel area can be made small to achieve a high PPI (Pixels per inch) display.
  • the waveguide grating coupler selects the color of the light, the display panel can eliminate the color film layer in the conventional LCD. Since the waveguide grating coupler directly couples the incident collimated backlight, the polarizer in the conventional LCD is omitted.
  • the display panel Since the wavelength and brightness of the reflected or transmitted light are dynamically changed by changing the surface area of the liquid, the display panel does not need to be provided with a thin film transistor and a black matrix in a conventional LCD, and each functional layer of the display panel is made of a transparent material, thereby realizing Transparent display with high transmittance can meet the needs of VR/AR. Due to the selection of the light-emitting direction of the waveguide grating coupler, the light emitted by the display panel can be concentrated to a certain position on the display panel, and when the pupil of the human eye is aligned with the position, the picture can be clearly viewed, so that the near-eye display can be realized. Since the optical waveguide layer also functions as a second substrate having a large thickness, the area of light entering is large, and thus has high light utilization efficiency.
  • the display panel according to an embodiment of the present disclosure may be implemented in various ways, and several implementations are exemplified below.
  • the first fluid 331 employs an aqueous fluid having electrical conductivity
  • the second fluid 332 employs an oily fluid having insulating properties
  • the surfaces of the first electrode layer 31 and the grating layer 32 have hydrophobic properties.
  • the hydrophobic characteristic surface refers to a surface on which the aqueous fluid condenses into a droplet shape when no voltage is applied.
  • FIG. 5 to FIG. 7 are schematic diagrams showing the gray scale display of the display panel according to the first embodiment of the present disclosure.
  • the aqueous fluid 333 has a large contact angle, is condensed in a teardrop shape and is located at the end of the display region, and the grating layer 32 is exposed to the oily fluid 334.
  • the middle layer is covered.
  • the difference between the refractive index of the oily fluid and the refractive index of the grating layer means that the difference between the refractive indices of the two fluids is greater than or equal to 0.1, and the refractive index of the aqueous fluid is similar to the refractive index of the grating layer.
  • the difference between the rates is less than or equal to 0.05.
  • the refractive index of the transparent oily fluid and the refractive index of the grating layer 32 can be made larger by selecting a suitable transparent oily fluid material, thereby maximizing the coupling efficiency.
  • the grating layer material is MY ⁇ 130 Polymer resin (refractive index is about 1.33), and when the transparent oily fluid material is acrylic acid (refractive index is 1.5-1.6), the difference between the refractive index of the oily fluid and the refractive index of the grating layer is 0.17. ⁇ 0.27.
  • the transparent oily fluid material may also be n-dodecane or the like.
  • the difference in refractive index between the aqueous fluid and the grating layer approaches zero, so that the aqueous fluid and the grating layer are completely optically integrated, and the grating effect of the grating layer is completely lost.
  • the aqueous fluid is water and the refractive index of water is 1.3
  • the difference between the refractive index of the aqueous fluid and the refractive index of the grating layer is about 0.03.
  • the materials of the first substrate and the second substrate may be glass or resin, have a thickness of 0.1 to 2 mm, and have a refractive index of 1.6 to 2.0, and the surface thereof is required to have good flatness and parallelism.
  • the refractive indices of the first substrate and the second substrate can be selected from 1.7 to 1.8, depending on product design or process conditions.
  • the optical waveguide layer is made of a material having a transparent, high refractive index relative to the first and second substrates, such as silicon nitride Si 3 N 4 , but is not limited thereto.
  • the first electrode layer and the second electrode layer are plate electrodes, and a transparent conductive material such as magnesium fluoride (MgF 2 ) or the like may be used, and the thickness is 50 to 1000 nm, and the refractive index is 1.3 to 1.4, which is determined by actual product design requirements.
  • the grating layer is made of a transparent dielectric material such as silica SiO 2 or a resin, and has a refractive index of 1.4 to 1.5, and the grating period is determined by the designed light-emitting direction and color, and the duty ratio is 0.1 to 0.9.
  • a duty cycle of 0.5 can be selected to facilitate processing.
  • the duty ratio can be set according to actual needs.
  • the thickness of the grating layer may be from 100 to 1000 nm.
  • the thickness of the grating layer can be set to 500 nm.
  • the three pixel regions R, G, and B can select the same grating height, but are not limited thereto, and can respectively be used for three pixels of R, G, and B according to actual needs.
  • the height of the grating layer of the area is designed.
  • the transparent water and the transparent oil used in the electrowetting layer 33 are not limited thereto, and the aqueous material having the same refractive index as that of the grating layer may be selected in combination with the material of the grating layer to realize the L0 state of the unpowered mode.
  • the oily fluid having the largest difference in refractive index from the material of the grating layer is selected to realize the L255 state (bright state) of the power-on mode.
  • the thickness of the electrowetting layer 33 is 1 to 5 ⁇ m so that the grating layer can be covered or it can be designed in combination with other parameters of the product.
  • the grating layer may be a one-dimensional grating or a two-dimensional grating.
  • light waves are electromagnetic waves, and the direction of propagation of light waves is the direction of propagation of electromagnetic waves.
  • both electrical vector E and magnetic vector H are perpendicular to the direction of propagation. Therefore, light waves are transverse waves and have polarization.
  • the vibration direction of the wave has no symmetry to the direction of propagation.
  • the asymmetry of the vibration direction of the wave to the direction of propagation is called polarization. It is the most obvious sign that the transverse wave is different from the longitudinal wave. Only the transverse wave has polarization.
  • FIG. 8 is a schematic structural view of a one-dimensional grating according to a first embodiment of the present disclosure.
  • the XY plane is parallel to the display plane
  • the one-dimensional grating includes a plurality of grating strips 321 arranged in the X direction, and the vibration direction of the wave is X-direction polarized light (e-light) can sense the change of the refractive index.
  • the polarized light (o light) whose vibration direction is in the Y direction does not change the refractive index, and the light coupled by the waveguide grating coupler is polarized e light.
  • Fig. 9 is a light emission spectrum diagram of a one-dimensional grating of the first embodiment of the present disclosure.
  • the e-light can sense the refractive index change, and the other polarized o-ray does not feel the refractive index change, which has a certain influence on the overall light utilization efficiency.
  • the one-dimensional grating is made of a transparent dielectric material, such as SiO 2 or a resin, and the grating period ⁇ is determined by the designed light-emitting direction and color, and the duty ratio is 0.1 to 0.9.
  • the duty cycle can be chosen to be 0.5 for ease of processing.
  • the duty cycle refers to the ratio of the width or equivalent width of the grating strip to the grating period.
  • FIGS. 10 and 11 are schematic views showing the structure of a two-dimensional grating according to a first embodiment of the present disclosure.
  • the XY plane is parallel to the display plane, and the two-dimensional grating includes a matrix arranged in the X direction and the Y direction, respectively.
  • the grating blocks 322 have the same refractive index matrix in the two-dimensional direction, and therefore can sense the refractive index changes of the polarized light (e light) in the X direction and the polarized light (o light) in the Y direction, respectively.
  • the light utilization rates of the o-light and the e-light are theoretically the same, and the light coupled by the waveguide grating coupler is polarized o-light and e-light.
  • Figure 12 is a diagram showing the light emission spectrum of a two-dimensional grating according to a first embodiment of the present invention. As shown in FIG. 12, in the white light range of 400 to 750 nm, both the o light and the e light can sense the refractive index change, and the light utilization rate is the same, and only one mode can be coupled to the one-dimensional grating. Dimensional gratings generally reduce the average half-width of the average (increased color purity), reduce interference from other colors, and improve light utilization.
  • the emission spectrum shown in Figures 9 and 12 is obtained by solving the Maxwell equation in the time domain and the frequency domain by the Finite Difference Time Domain (FDTD).
  • FDTD Finite Difference Time Domain
  • the two-dimensional grating adopts a transparent dielectric material, such as SiO 2 or resin, and the grating period ⁇ is determined by the designed light-emitting direction and color, and the duty ratio is 0.1 to 0.9.
  • the duty ratio can be selected to be 0.5.
  • the cross-sectional shape of the grating block may be a rectangle or a circle to form a two-dimensional block grating or a two-dimensional column grating.
  • the cross-sectional shape of the grating block may also be other regular shapes to meet actual needs, which is not limited in the present disclosure.
  • the grating layer includes a plurality of grating structures disposed corresponding to the respective pixel regions, and the grating period of the corresponding grating structure of each pixel region is fixed.
  • the grating period of each pixel region may be the same.
  • the light-emitting direction of each pixel region is directed to the set position, and the grating period of each pixel region may be different, and may be changed according to the setting mode.
  • the grating period may be set to be different for any two adjacent pixel regions, or the grating period may be set to be the same for a plurality of pixel regions, and then the plurality of pixel regions are different from the grating periods of the adjacent pixel regions.
  • the display panel structure and the grating structure according to the second embodiment of the present disclosure are the same as the display panel structure and the grating in the first embodiment, the first/second substrate, the first/second electrode layer, the first/second fluid, and The material of the grating layer is also the same as in the first embodiment.
  • the surfaces of the first electrode layer and the grating layer of the present embodiment have hydrophilic properties.
  • the hydrophilic characteristic surface refers to a surface on which the aqueous fluid wets on the surface without applying a voltage to cover the entire surface.
  • the gray scale display process of the embodiment is: when the first electrode layer and the second electrode layer are not applied with voltage, the contact angle of the aqueous fluid on the hydrophilic property surface is small, and the aqueous fluid is on the surface of the first electrode layer and the grating layer. Wetting and spreading the entire surface, the grating layer is completely covered by the aqueous fluid. Since the refractive index of the aqueous fluid is close to the refractive index of the grating layer, the aqueous fluid and the grating layer form a whole, the effect of the grating layer disappears, and the light cannot pass through the waveguide. Coupling in the layer, this is the L0 state (ie, the dark state).
  • the aqueous fluid When the first electrode layer and the second electrode layer are applied with an appropriate voltage V 0 , the aqueous fluid has a large contact angle, the aqueous fluid condenses in a droplet shape and is located at the end of the display region, and the grating layer is exposed to the oily fluid and covered by the oily fluid. Since the refractive index of the oily fluid differs greatly from the refractive index of the grating layer, the grating effect is obvious, the coupling effect of the light is strong, and the light is coupled out from the waveguide layer, which is the L255 state (ie, the bright state).
  • the contact angle of the aqueous fluid is between the above two cases, and the area ratio of the area of the aqueous fluid and the oily fluid covering the grating layer is due to Different gray levels can be achieved by different voltages.
  • the display panel structure and the grating structure are the same as those in the first embodiment, and the materials of the first/second substrate, the first/second electrode layer, and the grating layer are also the same as those in the first embodiment.
  • the first fluid of the present embodiment employs an aqueous fluid having insulating properties
  • the second fluid employs an oily fluid having conductive properties
  • the surfaces of the first electrode layer and the grating layer have oleophobic properties.
  • the aqueous fluid has insulating properties to remove the electrolyte in the aqueous fluid
  • the oily fluid has conductive properties to which conductive particles can be added.
  • the gray scale display process of the embodiment is: when the first electrode layer and the second electrode layer are not applied with voltage, the oily fluid has a large contact angle on the oleophobic characteristic surface, and the condensation is in the form of oil droplets and is located at the end of the display region.
  • the grating layer is exposed to the aqueous fluid and covered by the aqueous fluid. Since the refractive index of the aqueous fluid is close to the refractive index of the grating layer, the aqueous fluid and the grating layer are equivalent to a whole, the role of the grating layer disappears, and the light cannot be removed from the waveguide layer. Coupling, this is the L0 state (ie, the dark state).
  • the contact angle of the conductive oily fluid becomes small, and the grating layer is exposed to the oily fluid and completely covered by the oily fluid due to the refractive index of the oily fluid and the grating layer.
  • the refractive index differs greatly, the grating effect is obvious, the coupling effect of light is strong, and the light is coupled out from the waveguide layer, which is the L255 state (ie, the bright state).
  • the contact angle of the oily fluid is between the above two cases, and the area ratio of the area of the aqueous fluid and the oily fluid covering the grating layer is due to Different gray levels can be achieved by different voltages.
  • the embodiment may be modified accordingly, and the surfaces of the first electrode layer and the grating layer are set to be lipophilic, and the principle of realizing gray scale display is similar to the foregoing embodiment, and details are not described herein again.
  • Embodiments of the present disclosure provide a display panel and a display device provided with an electrowetting layer based on an electrowetting technique and a grating layer based on a waveguide grating coupling technique, and the color of the light is selected through the grating layer, thereby realizing the use of a color film.
  • the color display shows that the light direction is controlled by the grating layer, the polarizer is omitted, and the transparent layer is used for each functional layer, thereby realizing high transmittance display. Since the grating layer can couple the light in the range of the grating period of the micrometer or nanometer scale, the size of the pixel area can be made small, thereby realizing a high PPI display.
  • the combination of the electrowetting layer and the grating layer not only realizes a variable refractive index grating and a grating switch, but also achieves no viewing angle range limitation and fast response.
  • the emitted light is concentrated to the pupil position, which can realize near-eye display and meet the requirements of VR/AR.
  • a thicker optical waveguide layer it has higher light utilization efficiency, improves screen brightness, and reduces power consumption.
  • At least one embodiment of the present disclosure also provides a display device including the display panel of the foregoing embodiment and a side-entry collimating backlight 40.
  • the side-entry collimating backlight 40 is used to generate a collimated backlight, which can be made by dimming a semiconductor laser chip of red R, green G, and blue B, or by R, G with better collimation.
  • the B three-color LED chip is prepared by mixing light, or can be made by mixing light after the white LED chip with better collimation, or can be made by strip-shaped CCFL tube plus light collimation structure, the above light source structure
  • the light source in the embodiment of the present disclosure is not limited to the above structure.
  • the light-emitting direction of the side-entry collimating backlight 40 needs to be at an angle with the normal of the optical waveguide layer/second substrate, so that the incident light can form total reflection in the optical waveguide layer/second substrate while ensuring the waveguide grating.
  • the coupler has a certain light extraction efficiency.
  • the display device may be any product or component having a display function such as a VR helmet, VR glasses, a mobile phone, a tablet computer, a television, a display, a notebook computer, a digital photo frame, a navigator, or the like.
  • installation In the description of the embodiments of the present disclosure, it should be noted that the terms “installation”, “connected”, and “connected” are to be understood broadly, and may be, for example, a fixed connection or a Removable connection, or integral connection; may be mechanical connection or electrical connection; may be directly connected, or may be indirectly connected through an intermediate medium, and may be internal communication between the two elements.
  • the specific meanings of the above terms in the present disclosure can be understood in the specific circumstances by those skilled in the art.

Abstract

一种显示面板和显示装置。显示面板包括相对设置的光波导层(10)和第一基板(20)，还包括设置在光波导层(10)和第一基板(20)之间的电润湿控制层(30)，电润湿控制层(30)包括第一电极层(31)、第二电极层(34)以及设置在第一电极层(31)与第二电极层(34)之间的光栅层(32)和电润湿层(33)，光栅层(32)和电润湿层(33)用于实现从光波导层耦合出设定透射率、设定方向和设定波长的光线。

Description

显示面板和显示装置 技术领域
本公开的实施例涉及一种显示面板以及包含该显示面板的显示装置。
背景技术
目前，随着虚拟现实(Virtual Reality，VR)和增强现实(Augmented Reality，AR)产品的发展，对显示面板的透过率和分辨率(Pixels Per Inch，PPI)提出更高的要求，而惯常的显示结构难以满足未来的需求。
惯常的液晶显示(Liquid Crystal Display，LCD)和有机发光二极管(Organic Light Emitting Display，OLED)等显示技术，均无法做到显示面板的高度透明，从而影响面板后方光线的透过率以及透射的光谱。例如，惯常LCD装置包括背光源和显示面板，显示面板包括相对设置的阵列基板和彩膜基板，阵列基板和彩膜基板之间设置有液晶层，阵列基板的背面和彩膜基板的背面均设置有偏光片，由于偏光片和滤色器层等各功能层的影响，显示面板的透过率以及透射的光谱受到很大影响。同时，受制于制作工艺，惯常LCD和OLED难于实现高PPI，且受制于出射光线为发散光线，惯常LCD和OLED难于实现单眼聚焦的近眼显示。
发明内容
本公开的至少一个实施例提供了一种显示面板，包括相对设置的光波导层和第一基板，还包括设置在所述光波导层和第一基板之间的电润湿控制层，所述电润湿控制层包括第一电极层、第二电极层以及设置在所述第一电极层与第二电极层之间的光栅层和电润湿层，所述光栅层和电润湿层配置为实现从所述光波导层耦合出设定透射率、设定方向和设定波长的光线。
在本公开的一个实施例中，所述第一电极层设置在所述光波导层靠近第一基板一侧，所述第二电极层设置在所述第一基板靠近光波导层一侧，所述光栅层设置在所述第一电极层上，所述电润湿层设置在所述光栅层上。
在本公开的一个实施例中，所述电润湿层包括第一流体和第二流体，所 述第一流体的折射率与光栅层的折射率之差小于等于0.05，所述第二流体的折射率与光栅层的折射率之差大于等于0.1。
在本公开的一个实施例中，所述第一流体为具有导电特性的水性流体，所述第二流体为具有绝缘特性的油性流体；或者，所述第一流体为具有绝缘特性的水性流体，所述第二流体为具有导电特性的油性流体。
在本公开的一个实施例中，所述光波导层的一个或多个侧面用于入射准直背光，与所述光栅层形成波导光栅耦合器，所述光波导层的折射率大于所述第一电极层和所述光栅层的折射率。
在本公开的一个实施例中，所述显示面板还包括第二基板，所述光波导层设置在所述第二基板上，或所述光波导层与第二基板为一体结构。
在本公开的一个实施例中，所述光栅层为一维光栅，所述一维光栅包括沿同一方向排列的多个光栅条，所述一维光栅采用透明介质材料制备，厚度为100nm～1000nm，占空比为0.1～0.9。
在本公开的一个实施例中，所述光栅层为二维光栅，所述二维光栅包括阵列排布的多个光栅块，所述二维光栅采用透明介质材料制备，厚度为100nm～1000nm，占空比为0.1～0.9。
在本公开的一个实施例中，所述显示面板还包括第一保护膜和/或第二保护膜，所述第一保护膜设置在光波导层远离第一基板一侧的表面，所述第二保护膜设置在第一基板远离光波导层一侧的表面。
在本公开的一个实施例中，所述光栅层为纳米光栅层或微米光栅层。
本公开的至少一个实施例还提供了一种显示装置，包括上述的显示面板。
在本公开的一个实施例中，所述显示装置还包括侧入式准直背光器，产生准直背光的侧入式准直背光器设置在显示面板的一侧或多侧。
本公开的实施例提供了一种显示面板和显示装置，设置有基于电润湿技术的电润湿层和基于波导光栅耦合技术的光栅层，通过光栅层选择出光颜色，实现了不使用彩膜的彩色显示，通过光栅层控制出光方向，省去了偏光片，加之各功能层采用透明材料，从而实现了高透过率显示。由于光栅层在微米或纳米级的光栅周期范围内就可将光线耦合出来，因而像素区域的尺寸可以做得很小，从而实现了高PPI显示。通过电润湿层和光栅层结合不仅实现可变折射率的光栅和光栅开关，而且实现了没有视角范围限制和快速响应。通 过对出光方向的控制，将出射光线汇聚到瞳孔位置，可以实现近眼显示，满足VR/AR的需求。通过采用厚度较大的光波导层，具有较高的光利用率，提高了屏幕亮度，降低了功耗。
附图说明
为了更清楚地说明本公开实施例的技术方案，下面将对实施例的附图作简单地介绍，显而易见地，下面描述中的附图仅仅涉及本公开的一些实施例，而非对本公开的限制。
图1为根据本公开的一个实施例的显示面板的结构示意图；
图2为电润湿原理的示意图；
图3为基于电润湿显示的基本模型的示意图；
图4为根据本公开的一个实施例的波导光栅耦合器的工作原理图；
图5～图7为根据本公开第一实施例的显示面板实现灰阶显示的原理图；
图8为根据本公开第一实施例的一维光栅的结构示意图；
图9为根据本公开第一实施例的一维光栅的出光光谱图；
图10～图11为根据本公开第一实施例的二维光栅的结构示意图；以及
图12为根据本公开第一实施例的二维光栅的出光光谱图。
附图标记说明:
1—导电液滴； 2—基板； 3—电极；
4—第一介质滴； 5—第二介质； 10—光波导层；
20—第一基板； 30—电润湿控制层； 31—第一电极层；
32—光栅层； 33—电润湿层； 34—第二电极层；
331—第一流体； 332—第二流体； 333—水性流体；
334—油性流体。    
具体实施方式
为使本公开实施例的目的、技术方案和优点更加清楚，下面将结合本公开实施例的附图，对本公开实施例的技术方案进行清楚、完整地描述。显然，所描述的实施例是本公开的一部分实施例，而不是全部的实施例。基于所描述的本公开的实施例，本领域普通技术人员在无需创造性劳动的前提下所获 得的所有其他实施例，都属于本公开保护的范围。
本公开的至少一个实施例提供了一种基于电润湿技术的显示面板。图1为根据本公开的一个实施例的显示面板的结构示意图。如图1所示，本发明实施例显示面板的主体结构包括相对设置的光波导层10和第一基板20，以及设置在光波导层10和第一基板20之间的电润湿控制层30。光波导层10的一个或多个侧面用于入射准直背光，电润湿控制层30配置为实现光线在光波导层10中耦合出设定透射率、设定方向和设定波长的光线，即电润湿控制层30配置为设置每个像素区域的显示灰度(设定透射率)、设置每个像素区域的出光方向(设定方向)、设置每个像素区域的出光颜色(设定波长)，以在每个像素区域使特定颜色的光线以特定的显示灰度从特定方向出射。例如，可以设置三个像素区域形成一个像素，通过电润湿控制层30设置三个像素区域的显示灰度，设置三个像素区域的出光颜色分别为红光R、绿光G以及蓝光B，设置每个像素区域的出光方向为像素区域的中部，实现高透过率、高分辨率和近眼显示。
如图1所示，光波导层的左侧面配置为入射准直背光，当然，光波导层的多个侧面(例如，与左侧面相对的右侧面、图中未示出的前侧面和后侧面)可以配置为入射准直背光。准直背光以大于或等于临界角入射，在光波导层中传输时发生多次全反射，确保光在光波导层中远距离传输，且与电润湿控制层多次振荡耦合，将特定颜色的光线从光波导层中以特定方向耦合出来(详细过程将在下文进行说明)。例如，可以将光波导层作为第二基板，即第二基板和光波导层为一体结构，也可以单独设置第二基板，将光波导层设置在第二基板上，第二基板和第一基板通过封框胶对盒封装，并将电润湿控制层封装在盒内。此外，显示面板还可以包括设置在第一基板的背离光波导层/第二基板的一侧表面的第一保护膜，以及设置在光波导层/第二基板的背离第一基板的一侧表面的第二保护膜，第一保护膜和第二保护膜配置为保护显示面板。第一保护膜和第二保护膜可以为贴附在表面上的膜层，也可以为涂覆在表面上的涂层。
电润湿控制层30是基于电润湿技术的出光控制层。如图1所示，所述电润湿控制层30包括第一电极层31、光栅层32、电润湿层33和第二电极层34，其中，光栅层32设置在第一电极层31上，电润湿层33设置在光栅层 32上，第二电极层34设置在电润湿层33上。电润湿控制层33夹设在光波导层10和第一基板20之间，第一电极层31设置得邻近光波导层10，第二电极层34设置得邻近第一基板20。光波导层10和光栅层32形成波导光栅耦合器，实现对出光方向和出光颜色的选择，即波导光栅耦合器将特定波长的光以特定方向耦合出去(这将在下文进行描述)。第一电极层31和第二电极层34用于向电润湿层33施加电压，通过施加的电压强度，控制光栅层32和电润湿层33实现可变波导光栅耦合和光栅开关，控制出光的透射率，实现灰阶显示。电润湿层33包括具有导电特性的第一流体331和具有绝缘特性的第二流体332，或者包括具有绝缘特性的第一流体331和具有导电特性的第二流体332，通过改变第一电极层31和第二电极层34施加在导电液滴上的电压，改变导电液滴与光栅层的接触角，使得第一流体331和第二流体332不同程度地覆盖光栅层32，实现可变波导光栅耦合效果和光栅开关，实现灰阶显示。例如，第一电极层31可以与光波导层10的表面接触设置，也可以与光波导层10上设置的其它功能膜层接触设置；第二电极层34可以与第一基板20的表面接触设置，也可以与第一基板20上设置的其它功能膜层接触设置。
在本公开的实施例中，所述光栅层可以为微米光栅层或者纳米光栅层。
电润湿(Electrowetting，EW)显示技术的基础是液滴在介质上的电润湿现象。液滴在介质上的电润湿现象指的是通过改变施加在位于介质上的液滴上的电压来改变液滴在介质上的润湿性，即改变液滴与介质的接触角θ，使液滴发生形变和位移。图2为电润湿原理的示意图，示意了施加电压前后液滴与介质的接触角的变化。如图2所示，导电液滴1位于疏液性的基板2上，电极3对导电液滴1和基板2施加电压V，在施加电压前(V＝0)，导电液滴1与基板2的接触角为θ0，在施加电压后(V＝V0)，接触角发生显著变化，使液滴发生形变。
自1875年Lippman发现电润湿现象后，电润湿技术便得到了人们的广泛关注，主要研究与应用包括将电润湿技术应用于反射式、穿透式显示器、可转换式光学凹/凸微流体透镜、光纤通讯转换器以及生医芯片等。其中，利用电湿润技术作为新一代显示技术受到广泛关注，基于电湿润技术的显示模型也相继提出。
图3为基于电润湿显示的基本模型示意图，如图3所示，在施加电压前(V＝0)，染色的第一介质滴4润湿基板2的整个表面，此时，光线不能从染色的第一介质滴4通过，显示暗态。在施加电压后(V＝V0)，由于电润湿效应，第一介质滴4与基板2的接触角变化，收缩成一个小液滴并移动到端侧，透明的第二介质5铺满基板2，光线可以从透明的第二介质5通过，此时显示亮态。通过实践不同的电压，调整第一介质滴4与基板2的接触角，使第一介质滴4在基板2上占用的区域的面积不同，从而使透明的第二介质5在基板2上占用的区域的面积变化，可以显示不同的灰度，实现灰度显示。电润湿显示技术与液晶显示技术的主要区别在于，由于电润湿技术是通过改变液体的表面积来动态改变反射或者透射光波长和亮度，因此其不需要使用偏振片，无需极化，没有视角范围限制。同时，由于第一介质滴4在基板2上的电润湿现象响应于时间电压的速度比液晶响应于电压旋转的速度快，基于电润湿技术的显示装置的响应速度快。
波导光栅耦合器的基本原理是，入射光在波导中激发m阶导模，实现对出光方向和出光颜色的选择。图4为本发明实施例波导光栅耦合器的工作原理图。作为光波导层的一个或多个侧面入射准直背光后，当准直背光与光波导层的表面具有一夹角，且该夹角大于临界角时，进入光波导层的准直背光将发生全反射，产生m阶导模。通过光栅层与光波导层中特定模式的耦合，即可实现对出光方向和出光颜色的选择，即波导光栅耦合器将特定波长(颜色)的光在特定方向耦合出去。根据衍射光栅公式：
nisinθi-ndsinθd＝m*λ/Λ(m＝0,+/-1,2,…)
其中，ni和θi分别为入射空间折射率和入射角度，m为衍射级次，Λ为光栅周期，λ为入射光波长，θd为出光方向，即衍射光方向与显示面板平面法线之间的夹角，nd为电润湿层、第二电极以及第一基板的等效折射率(可以直接对三者求平均)。在实际实施时，出光方向可以由专业的光学仿真软件进行精确设计。在一般的AR/VR应用场景中，显示面板上某一位置上像素区域的出光方向往往是固定的，由该像素区域相对于人眼的位置决定，即上式中显示模式的出光方向θd是固定的。此时，通过调节光栅周期Λ，即可实现给定颜色(给定波长λ)的光线在出光方向θd上出射。如图4所示，白色入射光经过光栅层耦合出R、G、B三色光，且R色光的出光方向指向R 像素区域，G色光的出光方向指向G像素区域，B色光的出光方向指向B像素区域，实现特定颜色的光线以特定方向从每个像素区域出射。通过选择合适的光栅层材料、电极材料以及电润湿层材料，通过调节施加在电润湿层的电压，改变导电液滴的接触角，从而实现可变折射率的光栅和光栅开关。当然，在实施时，颜色的种类不局限于R、G、B三色，既可以是R、G、B、W(白色)四色，也可以是其它三色。
在本公开的实施例中，光栅周期Λ为几个微米或几百纳米级，就可以将光线从波导层中有效地耦合出来，且每个像素区域对应的光栅周期一般都比较小，因此每个像素区域的尺寸可以做得很小，从而实现高PPI(Pixels per inch，每英寸所拥有的像素数目)显示。由于波导光栅耦合器对于出光颜色的选择作用，因此显示面板可以省去惯常LCD中的彩膜层，由于波导光栅耦合器直接将入射准直背光耦合出来，因此省去了惯常LCD中的偏光片，由于通过改变液体的表面积来动态改变反射或者透射光波长和亮度，因此显示面板不需要设置惯常LCD中的薄膜晶体管和黑矩阵，且显示面板的各功能层均采用透明材料构成，从而实现了高透过率的透明显示，可以满足VR/AR的需求。由于波导光栅耦合器对出光方向的选择作用，可以将显示面板发出的光线汇聚到显示面板某一位置，当人眼瞳孔对准该位置时，能够清晰地观看画面，因此可以实现近眼显示。由于光波导层还作为厚度较大的第二基板，入光的面积大，因此具有较高的光利用率。
根据本公开的实施例的显示面板可以采用多种方式实现，下面对几种实现方式进行举例说明。
第一实施例
本实施例中，第一流体331采用具有导电特性的水性流体，第二流体332采用具有绝缘特性的油性流体，第一电极层31和光栅层32的表面具有疏水特性。其中，疏水特性表面指的是在不加电压时水性流体在该表面上凝结呈水滴状的表面。
图5～图7为本公开第一实施例显示面板实现灰阶显示的原理图。如图5所示，当第一电极层31和第二电极层34不加电压时，水性流体333接触角大，凝结呈水滴状且位于显示区域的端部，光栅层32暴露在油性流体334中并被覆盖，当油性流体334的折射率与光栅层32的折射率相差较大时，光 栅作用最明显，光的耦合作用最强，光线从波导层耦合出来，此时为L255状态(灰阶最高，即亮态)。如图6所示，当第一电极层31和第二电极层34施加适当电压V0后，水性流体333的接触角变小，光栅层32被水性流体333完全覆盖，当水性流体333的折射率与光栅层32的折射率相近时，水性流体333和光栅层32在光学上相当于一个整体，光栅层32的光栅功能消失，光无法从波导层中耦合出来，此时为L0状态(灰阶最低，即暗态)。如图7所示，当第一电极层31和第二电极层34施加的电压介于0与V0时，水性流体333的接触角介于以上两种情况之间，水性流体333或油性流体334覆盖光栅层32的区域的面积比值由于所加电压的不同而不同，即可实现不同的灰阶状态。本实施例中，油性流体的折射率与光栅层的折射率相差较大是指，两者折射率之差大于等于0.1，水性流体的折射率与光栅层的折射率相近是指，两者折射率之差小于等于0.05。
实施时，可以通过选择合适的透明油性流体材料，使得透明油性流体的折射率与光栅层32的折射率相差较大，最大限度地提高耦合效率。例如，光栅层材料采用MY～130Polymer resin(折射率为1.33左右)，当透明油性流体材料采用丙烯酸(折射率为1.5～1.6)时，油性流体的折射率与光栅层的折射率之差为0.17～0.27。透明油性流体材料也可以采用正十二烷等。同样，通过选择合适的水性流体，使得水性流体与光栅层的折射率之差趋近于零，使水性流体和光栅层在光学上完全成为一个整体，光栅层的光栅作用完全消失。例如，水性流体采用水，水的折射率为1.3，则水性流体的折射率与光栅层的折射率之差约为0.03。第一基板和第二基板的材料可以采用玻璃或树脂，厚度为0.1～2mm，折射率为1.6～2.0，，要求其表面具有较好的平整度及平行度。例如，可以将第一基板和第二基板的折射率选择为1.7～1.8，由产品设计或工艺条件决定。光波导层采用透明、折射率相对第一、第二基板高的材料制成，如氮化硅Si3N4等，但不限于此。第一电极层和第二电极层为平板电极，可以采用透明导电材料，如氟化镁(MgF2)等，厚度50～1000nm，折射率为1.3～1.4，由实际的产品设计需求而定。光栅层采用透明介质材料，如二氧化硅SiO2或树脂等，折射率为1.4～1.5，其光栅周期由设计的出光方向以及颜色决定，占空比为0.1～0.9。例如，可以选择占空比为0.5，以便于加工。在实施时，为了调节出光的光强及不同位置亮度差异，可以根据实际需要设置 占空比。光栅层的厚度可以为100～1000nm。例如，可以将光栅层的厚度设置为500nm。考虑到波导光栅的耦合对光栅层的高度不是特别敏感，R、G、B三个像素区域可以选择相同的光栅高度，但不限于此，可以根据实际需要分别针对R、G、B三个像素区域的光栅层高度进行设计。电润湿层33采用的透明的水和透明的油，但不限于此，可以结合光栅层的材料综合选择，选择与光栅层材料折射率相同的水性流体，以实现不加电方式的L0状态(暗态)，选择与光栅层材料折射率相差最大的油性流体，以实现加电方式的L255状态(亮态)。电润湿层33的厚度为1～5μm，从而可以覆盖光栅层，也可以结合产品的其他参数进行设计。
本实施例中，光栅层可以是一维光栅，也可以是二维光栅。众所周知，光波是电磁波，光波的传播方向是电磁波的传播方向，电磁波在自由空间中传播时，电矢量E和磁矢量H都与传播方向垂直，因此光波是横波，具有偏振性。对横波来说，波的振动方向对传播方向没有对称性，波的振动方向对于传播方向的不对称性叫做偏振，它是横波区别于纵波的一个最明显的标志，只有横波才有偏振现象。
图8为本公开的第一实施例的一维光栅的结构示意图。如图8所示，XY平面与显示平面平行，一维光栅包括沿X方向依次排列的多个光栅条321，波的振动方向为X方向的偏振光(e光)能感受到折射率的变化，而振动方向为Y方向的偏振光(o光)感受不到折射率的变化，此时波导光栅耦合器耦合出来的光为偏振的e光。
图9为本公开第一实施例的一维光栅的出光光谱图。如图9所示，在400～750nm的白光范围内，e光能感受到折射率变化，而另一种偏振的o光感受不到折射率变化，对整体光利用率有一定影响。实施时，一维光栅由透明介质材料制成，如SiO2或树脂等，其光栅周期Λ由设计的出光方向以及颜色决定，占空比为0.1～0.9。例如，可以将占空比选择为0.5，以便于加工。占空比是指光栅条的宽度或等效宽度与光栅周期之比。
图10和11为本公开的第一实施例的二维光栅的结构示意图，如图10和11所示，XY平面与显示平面平行，二维光栅包括分别沿X方向和Y方向矩阵排列的多个光栅块322，在二维方向上的折射率矩阵相同，因此能分别感受到X方向的偏振光(e光)和Y方向的偏振光(o光)的折射率变化， 且o光和e光的光利用率理论上相同，此时波导光栅耦合器耦合出来的光为偏振的o光和e光。
图12为本发明第一实施例二维光栅的出光光谱图。如图12所示，在400～750nm的白光范围内，o光和e光都能感受到折射率变化，且出光光利用率率相同，相较于一维光栅只能耦合一种模式，二维光栅总体上可以使平均半峰宽变窄(色纯度提高)、降低其他颜色的干扰、以及提升光利用率。图9、12所示的出光光谱，是通过时域有限差分法(Finite Difference Time Domain，FDTD)在时域和频域求解麦克斯韦方程得到的。实施时，二维光栅采用透明介质材料，如SiO2或树脂等，其光栅周期Λ由设计的出光方向以及颜色决定，占空比为0.1～0.9，例如，可以将占空比选为0.5，以便于加工。光栅块的横截面形状可以是矩形，也可以是圆形，形成二维块状光栅或二维柱状光栅。实际实施时，光栅块的横截面形状还可以是其它规则形状，以适应实际需要，本公开对此不做限定。
在该实施例中，光栅层包括与各个像素区域对应设置的多个光栅结构，每个像素区域对应的光栅结构的光栅周期固定。实施时，各个像素区域的光栅周期可以相同，但为了控制各个像素区域的出光方向，使各个像素区域的出光方向朝向设定位置，各个像素区域的光栅周期也可以不同，按照设定方式变化。例如，既可以设置成任意相邻两个像素区域的光栅周期不同，也可以设置成若干个像素区域的光栅周期相同，然后若干个像素区域与相邻的若干个像素区域的光栅周期不同。
第二实施例
根据本公开的第二实施例显示面板结构、光栅结构与第一实施例中的显示面板结构、光栅相同，第一/第二基板、第一/第二电极层、第一/第二流体以及光栅层的材料也与第一实施例中的相同。与第一实施例不同的是，本实施例的第一电极层和光栅层的表面具有亲水特性。其中，亲水特性表面指的是在不加电压时水性流体在该表面上润湿而铺满整个表面的表面。
本实施例实现灰阶显示的过程为：当第一电极层和第二电极层不加电压时，水性流体在亲水特性表面上接触角小，水性流体在第一电极层和光栅层的表面上润湿且铺满整个表面，光栅层被水性流体完全覆盖，由于水性流体的折射率与光栅层的折射率相近，水性流体和光栅层形成一个整体，光栅层 的作用消失，光无法从波导层中耦合出来，此时为L0状态(即，暗态)。当第一电极层和第二电极层施加适当电压V0后，水性流体接触角大，水性流体凝结呈水滴状且位于显示区域的端部，光栅层暴露在油性流体中并由油性流体覆盖，由于油性流体的折射率与光栅层的折射率相差较大，光栅作用明显，光的耦合作用强，光线从波导层耦合出来，此时为L255状态(即，亮态)。当第一电极层和第二电极层施加的电压介于0与V0时，水性流体的接触角介于以上两种情况之间，水性流体和油性流体覆盖光栅层的区域的面积比值由于所加电压的不同而不同，可实现不同的灰阶状态。
第三实施例
本实施例中，显示面板结构、光栅结构与第一实施例中的相同，第一/第二基板、第一/第二电极层以及光栅层的材料也与第一实施例中的相同。与第一实施例不同的是，本实施例第一流体采用具有绝缘特性的水性流体，第二流体采用具有导电特性的油性流体，第一电极层和光栅层的表面具有疏油特性。其中，使水性流体具有绝缘特性可以去除水性流体中的电解质，使油性流体具有导电特性可以在其中添加导电粒子。
本实施例实现灰阶显示的过程为：当第一电极层和第二电极层不加电压时，油性流体在疏油特性表面上接触角大，凝结呈油滴状且位于显示区域的端部，光栅层暴露在水性流体中并由水性流体覆盖，由于水性流体的折射率与光栅层的折射率相近，水性流体和光栅层相当于一个整体，光栅层的作用消失，光无法从波导层中耦合出来，此时为L0状态(即，暗态)。当第一电极层和第二电极层施加适当电压V0后，导电的油性流体的接触角变小，光栅层暴露在油性流体中并被油性流体完全覆盖，由于油性流体的折射率与光栅层的折射率相差较大，光栅作用明显，光的耦合作用强，光线从波导层耦合出来，此时为L255状态(即，亮态)。当第一电极层和第二电极层施加的电压介于0与V0时，油性流体的接触角介于以上两种情况之间，水性流体和油性流体覆盖光栅层的区域的面积比值由于所加电压的不同而不同，即可实现不同的灰阶状态。
实际实施时，也可以对本实施例进行相应改变，将第一电极层和光栅层的表面设置成亲油特性，实现灰阶显示的原理与前述实施例相近，这里不再赘述。
本公开的实施例提供了一种显示面板和显示装置，设置有基于电润湿技术的电润湿层和基于波导光栅耦合技术的光栅层，通过光栅层选择出光颜色，实现了不使用彩膜的彩色显示，通过光栅层控制出光方向，省去了偏光片，加之各功能层采用透明材料，从而实现了高透过率显示。由于光栅层在微米或纳米级的光栅周期范围内就可将光线耦合出来，因而像素区域的尺寸可以做得很小，从而实现了高PPI显示。通过电润湿层和光栅层结合不仅实现了可变折射率的光栅和光栅开关，而且实现了没有视角范围限制和快速响应。通过对出光方向的控制，将出射光线汇聚到瞳孔位置，可以实现近眼显示，满足VR/AR的需求。通过采用厚度较大的光波导层，具有较高的光利用率，提高了屏幕亮度，降低了功耗。
本公开的至少一个实施例还提供了一种显示装置，显示装置包括前述实施例的显示面板和侧入式准直背光器40。其中，侧入式准直背光器40用于产生准直背光可以由红R、绿G、蓝B三色的半导体激光器芯片经过混光后制成，也可由准直性较好的R、G、B三色LED芯片经过混光后制成，还可由准直性较好的白光LED芯片经过混光后制成，或可由条状的CCFL灯管加光线准直结构制成，以上光源结构仅为举例，本公开实施例中光源不限于上述结构。侧入式准直背光器40的出光方向需要与光波导层/第二基板法线成一定夹角，以使得入射光可以在光波导层/第二基板内形成全反射的同时，保证波导光栅耦合器具有一定的出光效率。根据本公开实施例的显示装置可以为：VR头盔、VR眼镜、手机、平板电脑、电视机、显示器、笔记本电脑、数码相框、导航仪等任何具有显示功能的产品或部件。
在本公开实施例的描述中，需要理解的是，术语“中部”、“上”、“下”、“前”、“后”、“竖直”、“水平”、“顶”、“底”“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。
在本公开实施例的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通。 对于本领域的普通技术人员而言，可以具体情况理解上述术语在本公开中的具体含义。
以上所述仅是本公开的示范性实施方式，而非用于限制本公开的保护范围，本公开的保护范围由所附的权利要求确定。
本申请要求于2017年3月9日递交的中国专利申请No.201710138779.7的优先权，在此全文引用上述中国专利申请公开的内容以作为本申请的一部分。

Claims (12)

  1. 一种显示面板，包括相对设置的光波导层和第一基板，其还包括设置在所述光波导层和第一基板之间的电润湿控制层，所述电润湿控制层包括第一电极层、第二电极层以及设置在所述第一电极层与第二电极层之间的光栅层和电润湿层，所述光栅层和电润湿层可操作地实现从所述光波导层耦合出设定透射率、设定方向和设定波长的光线。
  2. 根据权利要求1所述的显示面板，其中，所述第一电极层设置在所述光波导层靠近第一基板一侧，所述第二电极层设置在所述第一基板靠近所述光波导层一侧，所述光栅层设置在所述第一电极层靠近所述第一基板的一侧，所述电润湿层设置在所述光栅层靠近所述第一基板的一侧。
  3. 根据权利要求1或2所述的显示面板，其中，所述电润湿层包括第一流体和第二流体，所述第一流体的折射率与光栅层的折射率之差小于或等于0.05，所述第二流体的折射率与光栅层的折射率之差大于或等于0.1。
  4. 根据权利要求3所述的显示面板，其中，第一电极层和光栅层的表面具有疏水特性，所述第一流体为具有导电特性的水性流体，所述第二流体为具有绝缘特性的油性流体；或者，第一电极层和光栅层的表面具有亲水特性，所述第一流体为具有绝缘特性的水性流体，所述第二流体为具有导电特性的油性流体。
  5. 根据权利要求1至4中任何一项所述的显示面板，其中，所述光波导层的一个或多个侧面用于入射准直背光，所述光波导层与所述光栅层形成波导光栅耦合器，其中，所述光波导层的折射率大于所述第一电极层和所述光栅层的折射率。
  6. 根据权利要求1至5中任何一项所述的显示面板，其还包括第二基板，所述光波导层设置在所述第二基板上，或所述光波导层与所述第二基板为一 体结构。
  7. 根据权利要求1至6中任何一项所述的显示面板，其中，所述光栅层为一维光栅，所述一维光栅包括沿同一方向排列的多个光栅条，所述一维光栅由透明介质材料制成，厚度为100nm～1000nm，占空比为0.1～0.9。
  8. 根据权利要求1至6中任何一项所述的显示面板，其中，所述光栅层为二维光栅，所述二维光栅包括阵列排布的多个光栅块，所述光栅块由透明介质材料制成，厚度为100nm～1000nm，占空比为0.1～0.9。
  9. 根据权利要求1至8中任何一项所述的显示面板，其还包括第一保护膜和/或第二保护膜，所述第一保护膜设置在所述光波导层远离所述第一基板一侧的表面和/或所述第二保护膜设置在所述第一基板远离光波导层一侧的表面。
  10. 根据权利要求1至8中任何一项所述的显示面板，其中，所述光栅层为纳米光栅层或微米光栅层。
  11. 一种显示装置，其包括权利要求1～10中任何一项所述的显示面板。
  12. 根据权利要求11所述的显示装置，其还包括侧入式准直背光器，产生准直背光的侧入式准直背光器设置在光波导层的至少一个侧面处。
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