CN108051936B - Display panel and driving method thereof, display device and driving method thereof - Google Patents

Display panel and driving method thereof, display device and driving method thereof Download PDF

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CN108051936B
CN108051936B CN201810005260.6A CN201810005260A CN108051936B CN 108051936 B CN108051936 B CN 108051936B CN 201810005260 A CN201810005260 A CN 201810005260A CN 108051936 B CN108051936 B CN 108051936B
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liquid crystal
grating
electrodes
display panel
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CN108051936A (en
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谭纪风
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BOE Technology Group Co Ltd
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    • 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
    • G02F1/1313—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 specially adapted for a particular application
    • 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
    • G02F1/13306—Circuit arrangements or driving methods for the control of single liquid crystal cells
    • 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
    • G02F1/1343—Electrodes
    • G02F1/134309—Electrodes characterised by their geometrical arrangement

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  • Nonlinear Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mathematical Physics (AREA)
  • Geometry (AREA)
  • Liquid Crystal (AREA)

Abstract

The embodiment of the invention provides a display panel and a driving method thereof, and a display device and a driving method thereof. The display panel comprises a first substrate and a second substrate which are arranged opposite to each other, and an electrode layer and a liquid crystal grating which are arranged between the first substrate and the second substrate, wherein the electrode layer is used for adjusting the grating period of the liquid crystal grating. The driving method of the display device includes: determining the relative positions of the eyes of the user and the display panel; determining the light emitting direction of each sub-pixel on the display panel according to the relative position; and adjusting the grating period of each sub-pixel according to the light emergent direction. The invention realizes the adjustability of the light emitting direction of the display panel, simplifies the design and the process flow, reduces the design and the production cost, and can provide the best viewing quality and use experience.

Description

Display panel and driving method thereof, display device and driving method thereof
Technical Field
The invention relates to the technical field of display, in particular to a display panel and a driving method thereof, and a display device and a driving method thereof.
Background
Currently, with the development of Virtual Reality (VR) and Augmented Reality (AR) technologies, higher requirements are put on transmittance and resolution (Pixels Per inc, PPI) of a display panel. The conventional Display technologies such as Liquid Crystal Display (LCD) and Organic Light Emitting Diode (OLED) cannot achieve high transparency of the Display panel. Meanwhile, the conventional LCD and OLED have difficulty in realizing high PPI due to the fabrication process. Further, the existing LCD and OLED have difficulty in implementing monocular focused near-eye display due to the fact that the emitted light is divergent light.
In order to realize high transparency, high PPI and near-to-eye display, the prior art proposes a display technology based on a waveguide grating coupling technology, which selects a light emitting direction and a light emitting color through a waveguide grating coupling structure, and can converge light emitted by a display panel to a set position, and realize high transparency and high PPI display.
The inventor of the application finds that the existing display panel based on the waveguide grating coupling technology needs to design the light emergent direction of each position on the display panel in advance, and then designs and manufactures the grating period of each position on the display panel according to the light emergent direction, so that the design and process flow are complex, and the production cost is high. Meanwhile, because the grating period of each position on the display device is fixed, the light emitting direction of the display device is also fixed, and a user needs to continuously adjust the eye position to adapt to the light emitting direction in use, so that the watching quality of the user is influenced, and the user experience is also influenced.
Disclosure of Invention
The technical problem to be solved by the embodiments of the present invention is to provide a display panel and a driving method thereof, a display device and a driving method thereof, so as to overcome the defects of complicated design and process flow, high production cost, influence on viewing quality and user experience, and the like in the prior art.
In order to solve the above technical problem, an embodiment of the present invention provides a display panel including a first substrate and a second substrate disposed opposite to each other, and an electrode layer and a liquid crystal grating disposed between the first substrate and the second substrate, wherein the electrode layer is used for adjusting a grating period of the liquid crystal grating.
Optionally, the electrode layer includes a plurality of electrodes arranged at intervals and respectively receiving independent voltage signals, and 2N +1 electrodes determine a liquid crystal grating with a grating period of 2N × L, where N is a positive integer greater than or equal to 1, and L is a sum of an electrode width and an electrode pitch.
Optionally, the electrode layers include a first electrode layer and a second electrode layer, the first electrode layer includes a plurality of first electrodes arranged at intervals, the second electrode layer includes a plurality of second electrodes arranged at intervals, and each first electrode is located between two second electrodes, or each second electrode is located between two first electrodes.
Optionally, the first electrode layer and the second electrode layer are both disposed on the first substrate, and an insulating layer is disposed between the first electrode layer and the second electrode layer; alternatively, the first electrode layer is disposed on a first substrate and the second electrode layer is disposed on a second substrate.
The embodiment of the invention also provides a display device which comprises the display panel.
In order to solve the above technical problem, an embodiment of the present invention further provides a driving method of a display panel, the display panel including a first substrate and a second substrate provided to a cell, and an electrode layer and a liquid crystal grating provided between the first substrate and the second substrate, the driving method including:
and applying a voltage signal to the electrode layer to adjust the grating period of the liquid crystal grating.
Optionally, the electrode layer comprises a plurality of electrodes arranged at intervals; applying a voltage signal to the electrode layer to adjust a grating period of the liquid crystal grating, comprising: and applying independent voltage signals to each electrode in the electrode layers, and determining a liquid crystal grating with a grating period of 2N L by 2N +1 electrodes, wherein N is a positive integer greater than or equal to 1, and L is the sum of the electrode width and the electrode spacing.
Optionally, applying an independent voltage signal to each of the electrode layers comprises:
applying voltage values V to an electrode 1, an electrode 2 and an electrode 2N +1 in the electrode layers respectively1、V2、.....、V2N+1Voltage signal of, wherein V1＝V2N+1，V2＝V2N，.....，VN-1＝VN+1，V1>V2>.....>VN-1>VN(ii) a Or applying voltage values V to the electrode 1, the electrode 2N +1 in the electrode layers respectively1、V2、.....、V2N+1Voltage signal of, wherein V1＝V2N+1，V2＝V2N，.....，VN-1＝VN+1，VN>VN-1>.....>V2>V1。
In order to solve the above technical problem, an embodiment of the present invention further provides a driving method of a display device, where the display device includes the foregoing display panel, and the driving method includes:
determining the relative positions of the eyes of the user and the display panel;
determining the light emitting direction of each sub-pixel on the display panel according to the relative position;
and adjusting the grating period of each sub-pixel according to the light emergent direction.
Optionally, adjusting a grating period of each sub-pixel according to the light exit direction includes:
determining the grating period of each sub-pixel according to the light emitting direction of each sub-pixel on the display panel;
and applying a voltage signal to an electrode layer of the display panel according to the grating period of each sub-pixel, and adjusting the grating period of the liquid crystal grating in each sub-pixel.
The embodiment of the invention provides a display panel and a driving method thereof, a display device and a driving method thereof. The embodiment of the invention does not need a complex process for manufacturing the grating period, simplifies the design and process flow, shortens the design and production time and reduces the design and production cost. When the system is used by a user, the system can adjust the grating period of each position on the display panel according to the eye position as long as the user adjusts the proper head-wearing position, so that the light emitting direction points to human eyes, and the optimal viewing quality and use experience can be provided.
Of course, not all of the advantages described above need to be achieved at the same time in the practice of any one product or method of the invention. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the embodiments of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the example serve to explain the principles of the invention and not to limit the invention. The shapes and sizes of the various elements in the drawings are not to scale and are merely intended to illustrate the invention.
FIG. 1 is a schematic diagram of waveguide grating coupling techniques;
FIG. 2 is a schematic structural diagram of a display panel according to an embodiment of the present invention;
FIGS. 3a to 3d are schematic diagrams illustrating adjusting the grating period of the liquid crystal grating according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of an embodiment of the present invention for forming a gray scale display;
FIGS. 5a to 5c are schematic structural diagrams of RGB sub-pixel liquid crystal gratings according to an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of a display panel according to a first embodiment of the present invention;
FIG. 7 is a schematic structural diagram of a display panel according to a second embodiment of the present invention;
FIG. 8 is a schematic diagram of the driving of electrodes of the display device according to the present invention.
Description of reference numerals:
10 — a first substrate; 20 — a second substrate; 30-a waveguide layer;
40-an electrode layer; 50-liquid crystal grating; 41 — a first electrode layer;
42-an insulating layer; 43 — a second electrode layer; 4A — first electrode;
4B-second electrode.
Detailed Description
The following detailed description of embodiments of the invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.
Fig. 1 is a schematic diagram of waveguide grating coupling technology. Optical waveguides are a relatively common basic component in optical communications and integrated optics. In order to efficiently couple light into or out of an optical waveguide, a grating coupler is commonly used. When the incident or emergent beam satisfies the formula: beta is aq＝βmqK (q is 0, ± 1, ± 2, …), the incident light excites m-order guided modes in the waveguide, or m-order guided modes are coupled out in a given direction. Wherein, betamIs the propagation constant of the m-order guided mode, betam＝k0Nm，NmIs the effective refractive index of m-order guided mode, K is the grating vector, K is 2 pi/lambda, K0The wave number, k, of light in vacuum 02 pi λ, Λ is the grating period. Let the included angle between the wave vector direction of incident light (or emergent light) and the vertical direction be thetaiThen, the phase matching relationship can be further expressed as:
k0ncsinθi＝k0Nm–q2π/Λ(q＝0，±1，±2，…)
if the waveguide substrate is a transparent medium, the input and output coupling is performed from the base side, and the phase matching relationship can be expressed as:
k0nssinθi＝k0Nm–q2π/Λ(q＝0，±1，±2，…)
wherein n iscIs the refractive index of air, nsIs the refractive index of the substrate, nfIs the refractive index of the waveguide.
For a display panel based on waveguide-grating coupling technology, a plurality of grating coupling structures are arranged on a waveguide layer, light of a given color is selected to be emitted in a given direction from light propagating in the waveguide layer, one or more grating coupling structures correspond to one sub-pixel in the display panel, the optical position can be determined according to a diffraction grating formula, and the diffraction grating formula is as follows:
nisinθi-ndsinθd＝m*λ/Λ(m＝0,±1,±2,…)
wherein n isiAnd thetaiRespectively the refractive index and the incident angle of an incident space, m is a diffraction order, Lambda is a grating period, Lambda is an incident light wavelength, and thetadIs the angle between the light-emitting direction and the normal of the panel plane, ndIs the equivalent refractive index of the layers above the grating coupling structure. In the existing AR/VR application scene design, the light emitting direction is designed by professional opticsThe simulation software carries out accurate design, the light-emitting direction of the sub-pixel at a certain position in the display panel is set to be fixed and is determined by the relative relation between the sub-pixel position and the eye design position, namely the eye position is considered to be fixed, and therefore the light-emitting direction theta in the diffraction grating formula is setdIs stationary. Therefore, by designing the grating period Λ, the light with a given color (wavelength λ) in a given light-emitting direction θ can be realizeddAnd upward emergent. After the grating period of each position of the display panel is designed according to the light emitting direction, the prior art generally adopts a coherent light interference method, and adopts a laser to respectively irradiate sub-pixels at different positions of the display panel to form different grating periods. For example: the method comprises the steps of adopting red laser emitted by a red laser to irradiate a region corresponding to a red sub-pixel R through an exposure grating so as to form a grating period in the red sub-pixel R, adopting green laser emitted by a green laser to irradiate a region corresponding to a green sub-pixel G through the exposure grating so as to form a grating period in the green sub-pixel G, and adopting blue laser emitted by a blue laser to irradiate a region corresponding to a blue sub-pixel B through the exposure grating so as to form a grating period in the blue sub-pixel B. Because the wavelengths of the exposure light emitted by the lasers with different colors are different, the number of the liquid crystal gratings formed in the sub-pixels with different colors is different, and the grating periods formed in the sub-pixels with different colors are different.
Therefore, the light-emitting direction of the conventional display panel is fixed because the fixed grating period of each sub-pixel is preset, so that each sub-pixel can only select light of a given color to emit in a given light-emitting direction. Because a professional optical simulation software is needed to design the light emitting direction, and a laser irradiation mode is needed to prepare the grating period of each sub-pixel, the design and process flow is complex, the production time is long, and the production cost is high. Since the light emitting direction is fixed, the user's eyes are required to watch at the designed position, if the user's eyes deviate from the designed position, the light emitting direction of the sub-pixels will deviate from the human eyes, and the quality of the picture seen by the human eyes will be poor. In actual use, since users who use VR devices are various, not only do different users wear different positions, but also the positions of eyes of different users are different, thus making it difficult for some users to adapt to the design position. Some users need to continuously adjust the head-wearing position and the eye position before using the display panel, so that the eyes can be aligned to the light-emitting direction to see the picture of the display panel clearly, and the adjusted position needs to be strictly kept in use. Obviously, the adjustment method has great uncertainty, and it is difficult to make the eyes completely align with the light-emitting direction, which affects the quality of the picture viewed by the user and the experience of the user in using the product.
In order to overcome the defects that the design and the process flow of the conventional display panel are complex, the production cost is high, the viewing quality and the user experience are influenced, and the like, the embodiment of the invention provides the display panel. The display panel comprises a first substrate and a second substrate which are arranged opposite to each other, and an electrode layer and a liquid crystal grating which are arranged between the first substrate and the second substrate, wherein the electrode layer is used for adjusting the grating period of the liquid crystal grating. The electrode layer comprises a plurality of electrodes which are arranged at intervals and respectively receive independent voltage signals, and 2N +1 electrodes determine a liquid crystal grating with a grating period of 2N L, wherein N is a positive integer greater than or equal to 1, and L is the sum of the electrode width and the electrode spacing. As an implementation manner, fig. 2 is a schematic structural diagram of a display panel according to an embodiment of the present invention. As shown in fig. 2, the main structure of the display panel includes a first substrate 10 and a second substrate 20 disposed opposite to each other, and a waveguide layer 30, an electrode layer 40 and a liquid crystal grating 50 disposed between the first substrate 10 and the second substrate 20, wherein the electrode layer 40 is used for adjusting a grating period of the liquid crystal grating 50, and the liquid crystal grating 50 is used for controlling light coupled out from the waveguide layer 30 and controlling light of a set wavelength among the light to emit light in a set direction and a set gray scale. Wherein the waveguide layer 30 is disposed on a surface of the first substrate 10 facing the second substrate 20, the electrode layer 40 is disposed on a surface of the waveguide layer 30 facing the second substrate 20, and the liquid crystal grating 50 is disposed between the electrode layer 40 and the second substrate 20.
In embodiments of the present invention, the waveguide layer 30 is used to perform an optical waveguide having an index of refraction that is at least greater than the index of refraction of the layers in contact with the waveguide layer 30. In order to make the waveguide layer capable of performing light waves as efficiently as possibleThe refractive index of the waveguide layer is preferably larger than that of the other layer structures in addition to the layer in contact with the waveguide layer, i.e. the refractive index of the waveguide layer is the largest in the display panel. The material of the waveguide layer being transparent, e.g. Si3N4And the like, but are not limited thereto. In particular implementations, the higher the index of refraction of the waveguide layer, the better, and the range of thickness of the waveguide layer includes, but is not limited to, 100nm to 10 μm. Preferably, the thickness of the waveguide layer is 100-200 nm, so that the grating layer can control the light outgoing direction and wavelength. The waveguide layer may be a single mode waveguide, i.e. thin enough, such as 100nm, to facilitate control of the exit direction and color by the grating, but is not limited thereto. When the collimation of the lateral collimating backlight is good or the mode coupling into the waveguide layer can be effectively controlled, the requirement on the thickness of the waveguide layer can be properly relaxed, and the thickness of hundreds of nanometers or even microns can be selected. In addition, the first substrate and the electrode layer also function as an auxiliary waveguide. Since the thickness of the first substrate and the electrode layer is larger than the thickness of the waveguide layer, a substantial part of the emitted light of the side-entry collimating backlight will be coupled into the first substrate and the electrode layer. Whereas the light emitted by a side-entry collimated backlight may not be perfectly collimated, there will always be a small divergence angle, and the light coupled into the first substrate and the electrode layer will also have a small divergence angle. Since the refractive indices of the first substrate and the electrode layer are smaller than the refractive index of the waveguide layer, light in the first substrate and the electrode layer will not be well bound but will be injected into the waveguide layer continuously and continuously, complementing the attenuation of the waveguide mode in the waveguide layer due to propagation or grating coupling.
In the embodiment of the present invention, the electrode layer 40 includes a plurality of electrodes arranged in sequence at equal intervals, each electrode receives an independent voltage signal, and the electric field formed by the plurality of electrodes causes adjacent liquid crystal molecules to generate corresponding deflection according to the electric field distribution, so as to form liquid crystal gratings with different grating periods. The liquid crystal grating controls light coupled out from the waveguide layer, and controls light with set wavelength in the light to emit light in set direction and set gray scale. That is to say, in the embodiment of the present invention, the grating period of the liquid crystal grating is determined by the number of the electrodes, and the grating period of the liquid crystal grating can be adjusted by adjusting the number of the electrodes.
Fig. 3a to 3d are schematic diagrams of adjusting the grating period of the liquid crystal grating according to the embodiment of the invention. As shown in fig. 3a to 3b, a liquid crystal layer 4 is provided between a first substrate 1 and a second substrate 2 which are oppositely disposed, and an electrode layer is provided on the first substrate 1. The electrode layer includes a plurality of electrodes arranged regularly, and is divided into a first electrode group including 2 electrodes, the first electrode group including electrodes 3a and 3b, and a second electrode group including electrodes 3c and 3 d. As shown in fig. 3a, the voltages applied to 2 electrodes in the electrode group are controlled so that the voltages on the 2 electrodes are equal. Since there is no voltage difference between the 2 electrode electrodes, the liquid crystal molecules in the liquid crystal layer 4 are not deflected. At this time, the liquid crystal molecules in the liquid crystal layer 4 have a fixed refractive index. As shown in fig. 3b, in the first electrode group, a voltage V1 is applied to the electrode 3a, and a voltage V0 is applied to the electrode 3 b; in the second electrode group, a voltage V0 is applied to the electrode 3c, and a voltage V1 is applied to the electrode 3 d. Wherein, V1-V0 is delta V1. Since the voltage difference Δ V1 exists between 2 electrodes in the first electrode group, liquid crystal molecules in the corresponding region above two electrodes of the first electrode group are deflected under the action of the electric field, thereby forming a right deflection pattern region. Since 2 electrodes in the second electrode group have a voltage difference- Δ V1 therebetween, liquid crystal molecules in a corresponding region above two electrodes of the second electrode group are deflected by an electric field, thereby forming a left deflection pattern region. Since the voltages of the electrodes 3b and 3c are the same, the liquid crystal molecules in the corresponding area above the 2 electrode groups are not deflected, thereby forming a non-deflection pattern area. Since the voltage differences between the electrodes in the 2 electrode groups are opposite, the liquid crystal molecules of the 2 electrode groups are deflected in opposite directions. At this time, liquid crystal molecules in the liquid crystal layer 4 are deflected to the right, deflected to the left, and undeflected, and have a certain refractive index difference therebetween. It should be noted that the left-right deflection in the drawings is only a schematic illustration of one type of deflection, and the liquid crystal molecule deflection may be in a plane parallel to the substrate.
As shown in fig. 3c, a liquid crystal layer 4 is disposed between the first substrate 1 and the second substrate 2 which are oppositely disposed, an electrode layer is disposed on the first substrate 1, the electrode layer includes a plurality of electrodes which are regularly arranged, and 3 electrodes are an electrode group, that is, each electrode group includes an electrode 3a, an electrode 3b and an electrode 3 c. The voltages applied to 3 electrodes in the electrode group are controlled so that the voltages on the 3 electrodes are equal. Since there is no voltage difference between the 3 electrode electrodes, the liquid crystal molecules in the liquid crystal layer 4 are not deflected. At this time, the liquid crystal molecules in the liquid crystal layer 4 have a fixed refractive index. In the electrode group, a voltage V1 was applied to the electrode 3a, a voltage V0 was applied to the electrode 3b, and a voltage V1, V1-V0 ═ Δ V1, was applied to the electrode 3 c. A voltage difference Δ V1 exists between the electrodes 3a and 3b, liquid crystal molecules in the corresponding region between the two electrodes are deflected to the right under the action of the electric field, a voltage difference- Δ V1 exists between the electrodes 3b and 3c, and liquid crystal molecules in the corresponding region between the two electrodes are deflected to the left under the action of the electric field. Since the electric field in the region corresponding to the electrode 3a is less affected by the voltage of the electrode 3c, the liquid crystal molecules in this region are deflected more. Similarly, since the electric field in the region corresponding to the electrode 3c is less influenced by the voltage of the electrode 3a, the liquid crystal molecules in the region are deflected more. Since the electric field in the region corresponding to the electrode 3b is affected by the voltage of the electrode 3a and the voltage of the electrode 3c at the same time, the liquid crystal molecules in the region are deflected less (or not deflected). Therefore, liquid crystal molecules in the areas corresponding to the electrodes 3a, 3b and 3c form a liquid crystal grating with a convex lens-like effect, the liquid crystal molecules in the liquid crystal grating have different deflection angles, and the liquid crystal molecules in the liquid crystal grating have a certain refractive index difference.
As shown in fig. 3d, a liquid crystal layer 4 is disposed between the first substrate 1 and the second substrate 2 which are oppositely disposed, an electrode layer is disposed on the first substrate 1, the electrode layer includes a plurality of electrodes which are regularly arranged, and 5 electrodes are an electrode group, that is, each electrode group includes an electrode 3a, an electrode 3b, an electrode 3c, an electrode 3d and an electrode 3 e. Voltage V2 was applied to electrode 3a, voltage V1 was applied to electrode 3b, voltage V0 was applied to electrode 3c, voltage V1 was applied to electrode 3d, and voltage V2 was applied to electrode 3e, where V2 > V1 > V0, V2-V1 ═ Δ V2, and V1-V0 ═ Δ V1. In the same manner as the above principle, the liquid crystal molecules in the region corresponding to the electrode 3a and the electrode 3b are deflected to the right by the electric field, and the liquid crystal molecules in the region corresponding to the electrode 3b and the electrode 3c are deflected to the right by the electric field, but the deflection angle is smaller than that of the former. The liquid crystal molecules in the region corresponding to the electrode 3d and the electrode 3e are left-deflected by the electric field, and the liquid crystal molecules in the region corresponding to the electrode 3c and the electrode 3d are left-deflected by the electric field, but the deflection angle is smaller than that of the former. The liquid crystal molecules in the region corresponding to the electrode 3c are deflected minimally (or not deflected). Therefore, liquid crystal molecules in the areas corresponding to the electrodes 3a, 3b, 3c, 3d and 3e form a liquid crystal grating with a convex lens-like effect, the liquid crystal molecules in the liquid crystal grating have different deflection angles, and the liquid crystal molecules in the liquid crystal grating have a certain refractive index difference.
Fig. 4 is a schematic diagram of forming a gray scale display according to an embodiment of the present invention. The refractive index of the liquid crystal molecules is [ no, ne ], no is the ordinary refractive index of the liquid crystal molecules, and ne is the extraordinary refractive index of the liquid crystal molecules, and the liquid crystal molecules can be deflected by applying a voltage signal to the electric field of the liquid crystal molecules through the electrode layer 40, so that the refractive index of the liquid crystal molecules is changed between no and ne. Taking the initial horizontal alignment of the liquid crystal as an example, the refractive index of the liquid crystal molecules in the initial state is no, and the refractive index of the liquid crystal molecules after voltage application is neff, where neff is determined by the following formula:
Figure BDA0001538413390000101
when the liquid crystal molecule deflection angle θ is 0, neff is no, and when the liquid crystal molecule deflection angle θ is 90, neff is ne. As shown in fig. 4, taking the initial horizontal alignment of the liquid crystal as an example, in the initial state, when no voltage is applied to each electrode of the electrode layer 40, the refractive index of the liquid crystal molecules is no, and thus the liquid crystal molecules have a fixed refractive index no. The fixed refractive index of the liquid crystal layer is such that the effect of the grating coupling is masked and light in the waveguide layer 30 is confined in the waveguide layer 30 and no light exits, which is a dark state, i.e. grey scale L0. Voltages are applied to the respective electrodes of the electrode layer 40, and the voltages applied to the respective electrodes are different, so that the liquid crystal molecules are deflected accordingly according to the electric fields formed by the voltages of the respective electrodes. Because the voltages of the electrodes are different, the electric field intensity of the regions where the electrodes are located is different, the liquid crystal molecules in the regions where the electrodes are located are different in deflection, and a certain refractive index difference exists between the liquid crystal molecules with a large deflection angle and the liquid crystal molecules with a small deflection angle (or no deflection), so that the liquid crystal grating 50 with the refractive index difference is formed. The refractive index difference of the liquid crystal grating 50 causes the light in the waveguide layer 30 to be coupled out, and the light satisfying the matching relationship is coupled out according to the foregoing diffraction grating formula, the coupling efficiency is related to the refractive index difference, the larger the difference is, the more obvious the grating coupling effect is, and the larger the coupling efficiency is. When the refractive index difference is ne-no, the refractive index difference is the largest, and the coupled light rays are the most, which is a bright state, i.e., an L255 gray scale. Intermediate gray scale states are when the refractive index difference is between 0 and ne-no. It should be noted that, the gray scale is to divide the brightness variation between the brightest and the darkest into several parts, the gray scale represents the gradation level with different brightness from the darkest to the brightest, the more the gradation level is, the more the picture effect can be presented, the more the picture effect is fine, the gray scale capable of representing 256 brightness gradations is 256 gray scales, and the 256 gray scales can include 256 gray scales from L0 gray scale to L255 gray scale.
As can be seen from the foregoing description, since the liquid crystal grating is determined by the number of electrodes, the size of the liquid crystal grating, i.e., the grating period of the liquid crystal grating, can be adjusted by adjusting the number of electrodes. In fig. 3c, 3 electrodes define a liquid crystal cell with a cell period Λ ═ 2 × L, L being the sum of the electrode width and the electrode spacing, and in fig. 3d, 5 electrodes define a liquid crystal cell with a cell period Λ ═ 4 × L. For a liquid crystal grating determined by 2N +1 electrodes, the grating period lambada is 2N L, N is a positive integer greater than or equal to 1, and L is the sum of the electrode width and the electrode spacing. In the case of determining the electrode width and pitch, the larger the number of electrodes, the larger the period. In practical implementation, the electrode structure and the electrode width can be designed, and the electrode width and the distance between the electrodes are made as small as possible under the premise of process limit allowance, so that the grating period of the liquid crystal grating can be continuously adjusted.
It can be seen from the foregoing description that, since the deflection angle of the liquid crystal molecules is related to the voltage difference between the electrodes, the larger the deflection angle of the liquid crystal molecules is, the smaller the deflection angle of the liquid crystal molecules is, and the smaller the deflection angle of the liquid crystal molecules is, the refractive index difference of the liquid crystal molecules in the liquid crystal grating can be adjusted by adjusting the voltage difference between the electrodes. The coupling efficiency of the waveguide layer coupling light is changed according to the change of the refractive index difference value of the liquid crystal grating, so the coupling efficiency of the waveguide layer coupling light can be adjusted by adjusting the voltage of each electrode. The liquid crystal grating or the liquid crystal lens makes liquid crystal molecules in the liquid crystal layer have different deflection angles according to different applied voltages so as to realize different refractive indexes for incident polarized light, and therefore the formation of the liquid crystal grating is related to the polarization direction of the incident light. For example, for an electrode structure forming a horizontal electric field, when the long axis direction of liquid crystal molecules is the same as the polarization direction of incident light, the voltage of the middle electrode is lower than that of the electrodes on both sides, and when the long axis direction of the liquid crystal molecules is arranged perpendicular to the plane, the voltage of the middle electrode is higher than that of the electrodes on both sides; for the vertical electric field structure, the liquid crystal molecules are vertically aligned, and the voltage of the middle electrode is greater than that of the electrodes at both sides.
Fig. 5a to 5c are schematic structural diagrams of the RGB sub-pixel liquid crystal grating according to the embodiment of the present invention, which are illustrated by the initial horizontal orientation of liquid crystal molecules under a horizontal electric field. Assuming that a liquid crystal grating is defined by 2N +1 electrodes (N is a positive integer greater than or equal to 1), the electrodes are called electrode 1, electrode 2N1、V2、.....、V2N+1In order to form one liquid crystal grating by the 2N +1 electrodes, V is required1＝V2N+1，V2＝V2N，.....，VN-1＝VN+1，V1>V2>.....>VN-1>VNAnd the grating period Lambda of the liquid crystal grating is 2N L, and L is the sum of the electrode width and the electrode spacing. When the 2N +1 electrodes are applied with corresponding voltage signals, respectively, the liquid crystal molecules in the corresponding regions of the electrodes will deflect to different degrees due to the voltage difference between the electrodes, and the liquid crystal molecules in the regions with higher voltage difference between the electrodes deflect to a larger extentAnd the liquid crystal molecules in the area where the lower voltage between the electrodes is positioned deflect less, so that the liquid crystal molecules in the area where the 2N +1 electrode is positioned form a liquid crystal grating similar to a convex lens structure. As shown in fig. 5a, for the B sub-pixel, N is set equal to 1, that is, the liquid crystal grating in the B sub-pixel is determined by 3 electrodes, and the grating period Λ ═ 2 × L, V of the liquid crystal grating1＝V3>V3And the adjacent 2 liquid crystal gratings can share the electrode 3, that is, the electrode 3 of the first liquid crystal grating is the electrode 1 of the next liquid crystal grating, and the voltages are the same. The grating period determined by the method can enable only the light with the specific wavelength being blue light and having the specific direction in the light to enter human eyes when the light coupled out from the waveguide layer passes through the liquid crystal grating of the B sub-pixel, and the light with other directions and other wavelengths cannot enter the human eyes, so that the human eyes receive the blue light emitted by the B sub-pixel. As shown in fig. 5b, N is set equal to 2 for the G sub-pixel, the liquid crystal grating in the G sub-pixel is determined by 5 electrodes, and the grating period Λ ═ 4 × L, V of the liquid crystal grating1＝V5>V2＝V4>V3The adjacent 2 liquid crystal gratings can share the electrode 5, that is, the electrode 5 of the first liquid crystal grating is the electrode 1 of the next liquid crystal grating, and the voltages are the same. The determined grating period can ensure that only the light with the specific wavelength being green light and having the specific direction in the light enters the human eyes when the light coupled out from the waveguide layer passes through the liquid crystal grating of the G sub-pixel, and the light with other directions and other wavelengths cannot enter the human eyes, so that the human eyes receive the green light emitted by the G sub-pixel. As shown in fig. 5c, N is set equal to 3 for the R sub-pixel, the liquid crystal grating in the R sub-pixel is determined by 7 electrodes, and the grating period Λ ═ 6 × L, V of the liquid crystal grating1＝V7>V2＝V6>V3＝V5>V4The adjacent 2 liquid crystal gratings can share the electrode 7, that is, the electrode 7 of the first liquid crystal grating is the electrode 1 of the next liquid crystal grating, and the voltages are the same. The grating period determined by the method can ensure that when the light coupled out from the waveguide layer passes through the liquid crystal grating of the R sub-pixel, only the light with specific wavelength of red light and specific directionThe light emitted from the R sub-pixel enters human eyes, and the light with other directions and other wavelengths cannot enter the human eyes, so that the human eyes receive the red light emitted from the R sub-pixel. Thus, the RGB sub-pixels can be adjusted to have different grating periods, so that the light of different sub-pixels can be all directed to human eyes. Similarly, different pixel positions on the display panel can be adjusted to have different grating periods, so that light rays at different positions on the display panel all point to human eyes.
In the embodiment of the invention, the electrodes in the electrode layer may be a plurality of electrode strips arranged in sequence or a plurality of electrode blocks arranged in an array, the electrode layer may be of a single-layer structure or a double-layer or multi-layer structure, and for the double-layer structure, both the electrode layers may be arranged on the first substrate to form a horizontal electric field, or may be arranged on the first substrate and the second substrate respectively to form a vertical electric field.
The embodiment of the invention provides a display panel, the grating period of a liquid crystal grating is determined by the number of electrodes, and the grating period of the liquid crystal grating can be adjusted by adjusting the number of the electrodes, so that the light emitting direction of the display panel can be adjusted. On one hand, in the design of the display panel, professional optical simulation software is not needed for designing the light emitting direction, and in the preparation of the display panel, a complex process for manufacturing the grating period is not needed, so that the design and process flow is simplified, the design and production time is shortened, and the design and production cost is reduced. On the other hand, when the user uses the system, the system can adjust the grating period of each position on the display panel according to the eye position as long as the user adjusts the proper head-mounted position, so that the light emitting direction points to human eyes, and the optimal viewing quality and use experience are provided.
According to the display panel provided by the embodiment of the invention, the light is controlled to be coupled out from the waveguide layer by adopting the waveguide grating coupling technology, and the light with the set wavelength in the light coupled out from the waveguide layer is controlled to be emitted in the set direction and the set gray level, so that a polarizing film and a color resistance are not required to be arranged in the display panel, and all components of the display panel are made of high-transmittance materials, so that the transmittance of the display panel is improved, high-transparency display is realized, and the display panel can be applied to transparent display products, virtual reality VR (virtual reality) or augmented reality AR (augmented reality). Because a polarizing plate is not required to be arranged in the display panel, the phase delay amount of the whole liquid crystal layer is not required, the liquid crystal box can be thinner, and the response time of the liquid crystal is improved. Because the grating period of the liquid crystal grating is smaller, namely within a few microns or hundreds of nanometers, the size of the sub-pixel can be smaller, and the display panel can realize high PPI display. Due to the selection effect of the grating coupling on the light-emitting direction, light rays for display can be selectively converged near human eyes, near-eye display capable of realizing monocular focusing is facilitated, and near-eye 3D display even capable of realizing monocular is realized.
The technical solution of the embodiment of the present invention is explained in detail by the specific embodiment below.
First embodiment
Fig. 6 is a schematic structural diagram of a display panel according to a first embodiment of the invention. As shown in fig. 6, the main structure of the display panel includes a first substrate 10 and a second substrate 20 disposed opposite to each other, and a waveguide layer 30, an electrode layer and a liquid crystal grating 50 disposed between the first substrate 10 and the second substrate 20, the electrode layer is used for adjusting a grating period of the liquid crystal grating 50, and the liquid crystal grating 50 is used for controlling light coupled out from the waveguide layer 30 and controlling light of a set wavelength among the light to be emitted in a set direction and in a set gray scale. Wherein the waveguide layer 30 is disposed on a surface of the first substrate 10 facing the second substrate 20, the electrode layer is disposed on a surface of the waveguide layer 30 facing the second substrate 20, and the liquid crystal grating 50 is disposed between the electrode layer and the second substrate 20. In this embodiment, the electrode layers include a first electrode layer 41, an insulating layer 42, and a second electrode layer 43 stacked in this order, the first electrode layer 41 is disposed on the waveguide layer 30, the insulating layer 42 covers the first electrode layer 41, and the second electrode layer 43 is disposed on the insulating layer 42. The first electrode layer 41 comprises a plurality of first electrodes 4A arranged at equal intervals in sequence, the second electrode layer 43 comprises a plurality of second electrodes 4B arranged at equal intervals in sequence, each first electrode 4A in the first electrode layer 41 is positioned between two second electrodes 4B, or each second electrode 4B in the second electrode layer 43 is positioned between two first electrodes 4A, the N first electrodes 4A and the N +1 second electrodes 4B define a liquid crystal grating, and N is a positive integer greater than or equal to 1. When it is determined that independent voltage signals are respectively applied to the plurality of electrodes of each liquid crystal grating 50, due to the voltage difference between the electrodes, liquid crystal molecules in the liquid crystal grating will deflect to different degrees, and a certain refractive index difference exists between the liquid crystal molecules with larger deflection and the liquid crystal molecules with smaller deflection, so that the liquid crystal grating couples light out of the waveguide layer 30, and the light with a set wavelength in the light is controlled to emit light in a set direction and a set gray scale.
In this embodiment, the display panel includes a plurality of sub-pixels, and each sub-pixel includes at least 2 liquid crystal gratings. The sub-pixels can be red sub-pixels, green sub-pixels or blue sub-pixels, the display panel comprises a plurality of red sub-pixels, green sub-pixels and blue sub-pixels which are arranged in an array, and the RGB sub-pixels are adjusted to have different grating periods. For example, the liquid crystal grating in the red sub-pixel is defined by 7 electrodes, 3 first electrodes 4A and 4 second electrodes 4B, respectively. The liquid crystal grating in the green sub-pixel is defined by 5 electrodes, 2 first electrodes 4A and 3 second electrodes 4B respectively. The liquid crystal grating in the blue sub-pixel is defined by 3 electrodes, 1 first electrode 4A and 2 second electrodes 4B respectively. In practical implementation, the positions of the first electrode layer and the second electrode layer may be adjusted according to actual needs, for example, the first electrode layer is disposed on the second electrode layer, or another film layer is disposed between the first electrode layer and the second electrode layer. Further, a plurality of electrode layers may be provided, or the first electrode layer and the second electrode layer may be combined into one electrode layer in this embodiment.
This embodiment is an electrode structure for forming a horizontal electric field, and is suitable for a display mode in which the optical axes of liquid crystal molecules are deflected in a plane parallel to the basal plane. In the display mode, the display panel further includes alignment layers respectively disposed on the first and/or second substrates, the alignment layers controlling initial alignment of the liquid crystal molecules such that the initial direction of the liquid crystal molecules is parallel to the first and second substrates. In addition, the display panel may further include a black shielding layer or a reflection layer on the side of the waveguide layer, the black shielding layer being configured to absorb light emitted from the side of the waveguide layer, and the reflection layer being configured to reflect light emitted from the side of the waveguide layer. Further, the display panel can further comprise a protective film arranged on the surface of the first substrate on the side away from the second substrate, and a protective film arranged on the surface of the second substrate on the side away from the first substrate, so that the display panel is protected. The protective film can be a film layer attached to the surface or a coating coated on the surface.
The electrode structure for forming a horizontal electric field according to the present embodiment is also applicable to a display mode in which the optical axes of the liquid crystal molecules are deflected in a plane perpendicular to the basal plane. In the display mode, the voltage relationship among the electrodes of one liquid crystal grating is determined as follows: vN-1＝VN+1，VN>VN-1>.....>V2>V1And will not be described in detail herein.
In this embodiment, the first substrate and the second substrate may be made of glass or resin, and have a thickness of 0.1mm to 2mm, and the parameters thereof are determined by specific product design or process conditions, and the upper and lower surfaces thereof are required to have better flatness and parallelism. In practical implementation, the first substrate and the second substrate may also be made of other materials, which is not limited herein. The electrode layer can be made of transparent conductive material, such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO), and has a thickness of 50 nm-1000 nm, preferably 100-200 nm. Alternatively, the electrode layer may be made of a thin metal material, such as Au or Ag-Mg alloy, with a thickness of 30nm to 200 nm. The thickness of the liquid crystal layer is several hundred nanometers to several micrometers, and is generally controlled to be about 1 μm.
Second embodiment
Fig. 7 is a schematic structural diagram of a display panel according to a second embodiment of the invention. As shown in fig. 7, the main structure of the display panel includes a first substrate 10 and a second substrate 20 disposed opposite to each other, and a waveguide layer 30, an electrode layer and a liquid crystal grating 50 disposed between the first substrate 10 and the second substrate 20, the electrode layer is used for adjusting a grating period of the liquid crystal grating 50, and the liquid crystal grating 50 is used for controlling light coupled out from the waveguide layer 30 and controlling light of a set wavelength among the light to be emitted in a set direction and in a set gray scale. Wherein the waveguide layer 30 is disposed on a surface of the first substrate 10 facing the second substrate 20, the electrode layers include a first electrode layer 41 disposed on a surface of the waveguide layer 30 facing the second substrate 20 and a second electrode layer 43 disposed on a surface of the second substrate 20 facing the first substrate 10, and the liquid crystal grating 50 is disposed between the first electrode layer 41 and the second electrode layer 43. The first electrode layer 41 comprises a plurality of first electrodes 4A arranged at equal intervals in sequence, the second electrode layer 43 comprises a plurality of second electrodes 4B arranged at equal intervals in sequence, each first electrode 4A in the first electrode layer 41 is positioned between two second electrodes 4B, or each second electrode 4B in the second electrode layer 43 is positioned between two first electrodes 4A, the N first electrodes 4A and the N +1 second electrodes 4B define a liquid crystal grating, and N is a positive integer greater than or equal to 1. When it is determined that independent voltage signals are respectively applied to the plurality of electrodes in each liquid crystal grating 50, due to the voltage difference between the electrodes, liquid crystal molecules in the liquid crystal grating will deflect to different degrees, and a certain refractive index difference exists between the liquid crystal molecules with larger deflection and the liquid crystal molecules with smaller deflection, so that the liquid crystal grating couples light out of the waveguide layer 30, and the light with a set wavelength in the light is controlled to emit light in a set direction and a set gray scale.
In this embodiment, for each grating structure, each first electrode 4A and each second electrode 4B respectively receive an independent voltage signal, so that liquid crystal molecules of a sub-pixel where the grating structure is located generate corresponding deflection according to electric field distribution, thereby forming a liquid crystal grating. Assuming that the electrodes 1, 2N +1 included in the sub-pixels are sequentially called as an electrode 1, an electrode 2, 2N +1, wherein the electrode 1, the electrode 3, 2N +1 is a first electrode 4A, the electrode 2, the electrode 4, 2N is a second electrode 4B, and the voltage signals applied to the electrode 1, the electrode 2, 2N +1 are respectively: v1、V2、.....、V2N+1，V1＝V2N+1，V2＝V2N，.....，VN-1＝VN+1，VN>VN-1>.....>V2>V1. In practice, the electrode 1, the electrode 3, theA。
This embodiment is an electrode structure for forming a vertical electric field, and is suitable for a display mode in which the optical axes of liquid crystal molecules are deflected in a plane perpendicular to the basal plane.
Third embodiment
Based on the technical idea of the foregoing embodiment, an embodiment of the present invention further provides a driving method of a display panel, where the display panel adopts the structure of the foregoing embodiment, and includes a first substrate and a second substrate that are disposed opposite to each other, and an electrode layer and a liquid crystal grating that are disposed between the first substrate and the second substrate, where the electrode layer includes a plurality of electrodes arranged at intervals. The driving method of the display panel of the embodiment comprises the following steps:
and applying a voltage signal to the electrode layer to adjust the grating period of the liquid crystal grating.
Specifically, independent voltage signals are applied to each electrode in the electrode layers, and a liquid crystal grating with a grating period of 2N L is determined by 2N +1 electrodes, wherein N is a positive integer greater than or equal to 1, and L is the sum of the electrode width and the electrode spacing.
In one embodiment, the electrode layers form a horizontal electric field, and the application of independent voltage signals to each of the electrodes in the electrode layers while deflecting the optical axes of the liquid crystal molecules in parallel to the in-plane of the first substrate includes:
applying voltage values V to an electrode 1, an electrode 2 and an electrode 2N +1 in the electrode layers respectively1、V2、.....、V2N+1Voltage signal of, wherein V1＝V2N+1，V2＝V2N，.....，VN-1＝VN+1，V1>V2>.....>VN-1>VN。
In another embodiment, the applying of independent voltage signals to each of the electrode layers when the electrode layers form a horizontal electric field and the optical axes of the liquid crystal molecules are deflected perpendicular to the in-plane of the first substrate includes:
applying voltage values V to an electrode 1, an electrode 2 and an electrode 2N +1 in the electrode layers respectively1、V2、.....、V2N+1Voltage signal of, wherein V1＝V2N+1，V2＝V2N，.....，VN-1＝VN+1，VN>VN-1>.....>V2>V1。
In yet another embodiment, applying independent voltage signals to each of the electrode layers while the electrode layers form a vertical electric field includes:
applying voltage values V to an electrode 1, an electrode 2 and an electrode 2N +1 in the electrode layers respectively1、V2、.....、V2N+1Voltage signal of, wherein V1＝V2N+1，V2＝V2N，.....，VN-1＝VN+1，VN>VN-1>.....>V2>V1。
Fourth embodiment
The embodiment of the invention also provides a display device, which comprises the display panel and the lateral collimating backlight device of the embodiment. The lateral type collimation backlight device is used for generating collimation backlight and is arranged on the side face of the waveguide layer/the first substrate/the electrode layer. The side-in collimating backlight device can be made by mixing red R, green G and blue B semiconductor laser chips, can also be made by mixing R, G, B three-color LED chips with better collimation, can also be made by mixing white LED chips with better collimation, or can be made by a strip-shaped CCFL tube and some light collimating structures. The light-emitting direction of the side-entry collimating backlight needs to form a certain included angle with the normal of the waveguide layer/the first substrate/the electrode layer, so that the waveguide grating coupler is ensured to have certain light-emitting efficiency while incident light can form total reflection in the waveguide layer/the first substrate/the electrode layer.
The display device provided by the embodiment of the invention can be as follows: the display device comprises any product or part with 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 and the like.
Fifth embodiment
Based on the technical idea of the foregoing embodiment, an embodiment of the present invention further provides a driving method of a display device, where the display device includes the display panel of the foregoing embodiment. The driving method of the display device of the embodiment comprises the following steps:
s1, determining the relative positions of the eyes of the user and the display panel;
s2, determining the light emitting direction of each sub-pixel on the display panel according to the relative position;
and S3, adjusting the grating period of each sub-pixel according to the light emitting direction of each sub-pixel on the display panel.
Wherein, step S3 includes:
s31, determining the grating period of each sub-pixel according to the light emitting direction of each sub-pixel on the display panel;
s32, according to the grating period of each sub-pixel, a voltage signal is applied to the electrode layer of the display panel to adjust the grating period of the liquid crystal grating in each sub-pixel.
In step S32, the number of electrodes required to determine the grating period is calculated according to the grating period of each sub-pixel, and then independent voltage signals are applied to the electrodes in the electrode layer according to the driving method of the fourth embodiment to adjust the grating period of the liquid crystal grating in each sub-pixel.
FIG. 8 is a schematic diagram of the driving of electrodes of the display device according to the present invention. To simplify the driving circuit, the sub-pixels on the display panel may be driven in groups, and the embodiment is illustrated in 50 groups. The sub-pixels on the display panel are divided into 50 groups, and 25 groups are symmetrical left and right. After the position relationship between the human eyes and the display panel is determined, each group can calculate the corresponding grating period according to different included angles between the positions of the groups and the human eyes. In this embodiment, it may be set that the grating periods of the R sub-pixels in each group are the same (the number of electrodes is the same), the grating periods of the G sub-pixels are the same, and the grating periods of the B sub-pixels are the same, that is, only three grating periods are provided in each group, and then 25 groups only need to calculate 25 × 3 grating periods. In order to ensure the light coupling effect, each sub-pixel is arranged to comprise 2 liquid crystal gratings.
As shown in FIG. 8, for example, the B sub-pixels in a group are driven by 5 electrodes, V1＝V5>V2＝V4>V3The first electrode of the second liquid crystal grating is shared with the last electrode of the first liquid crystal grating, and the driving modes of all the B sub-pixels in the group are the same. In practical implementation, the driving modes (driving voltages of corresponding electrodes) of the B sub-pixels in the same group may also be different, because the driving voltages only affect the morphology and height of the liquid crystal grating, and do not affect the grating period. To further simplify the driving, the maximum voltage applied to the electrodes in all the groups may be common, and the minimum voltage applied to the electrodes in all the groups may be common. As shown in fig. 8, the driving pattern of the group 1B sub-pixel is the same as that of the group 50B sub-pixel, the driving pattern of the group 2B sub-pixel is the same as that of the group 49B sub-pixel, and so on, and the driving pattern of the group 25B sub-pixel is the same as that of the group 26B sub-pixel. The B sub-pixels in the 1 st and 50 th groups drive 5 electrodes of each liquid crystal grating, the first electrode layer comprises electrode 1, electrode 3 and electrode 5, the second electrode layer comprises electrode 2 and electrode 4, because of V1＝V5>V2＝V4>V3Therefore, the first electrode layer needs to apply 2 different sets of voltage signals V1And V3The second electrode layer only needs to apply a set of same voltage signals V2。
In the description of the embodiments of the present invention, it is to be understood that the terms "medial", "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are intended only to facilitate the description of the invention and to simplify the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be construed as limiting the invention.
In the description of the embodiments of the present invention, it should be noted that, unless otherwise specifically stated or limited, the terms "mounted", "connected" and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Although the embodiments of the present invention have been described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (8)

1. The display panel is characterized by comprising a first substrate and a second substrate which are arranged opposite to each other, and an electrode layer and a liquid crystal grating which are arranged between the first substrate and the second substrate, wherein the electrode layer comprises a plurality of electrodes which are arranged at intervals and respectively receive independent voltage signals, each electrode of the electrode layer is used for being applied with the independent voltage signals, the grating period of the liquid crystal grating is adjusted by adjusting the number of the electrodes, 2N +1 electrodes determine the liquid crystal grating with the grating period of 2N L, N is a positive integer which is greater than or equal to 1, and L is the sum of the electrode width and the electrode spacing.
2. The display panel according to claim 1, wherein the electrode layer comprises a first electrode layer and a second electrode layer, the first electrode layer comprises a plurality of first electrodes arranged at intervals, the second electrode layer comprises a plurality of second electrodes arranged at intervals, and each first electrode is located between two second electrodes or each second electrode is located between two first electrodes.
3. The display panel according to claim 2, wherein the first electrode layer and the second electrode layer are both provided over a first substrate with an insulating layer provided therebetween; alternatively, the first electrode layer is disposed on a first substrate and the second electrode layer is disposed on a second substrate.
4. A display device comprising the display panel according to any one of claims 1 to 3.
5. A driving method of a display panel is characterized in that the display panel comprises a first substrate and a second substrate which are arranged opposite to each other, and an electrode layer and a liquid crystal grating which are arranged between the first substrate and the second substrate, wherein the electrode layer comprises a plurality of electrodes which are arranged at intervals; the driving method includes:
and applying independent voltage signals to each electrode of the electrode layer, adjusting the grating period of the liquid crystal grating by adjusting the number of the electrodes, and determining a liquid crystal grating with the grating period of 2N x L by 2N +1 electrodes, wherein N is a positive integer greater than or equal to 1, and L is the sum of the electrode width and the electrode spacing.
6. The driving method according to claim 5, wherein applying independent voltage signals to each of the electrode layers comprises:
applying voltage values V to an electrode 1, an electrode 2 and an electrode 2N +1 in the electrode layers respectively1、V2、.....、V2N+1Voltage signal of, wherein V1＝V2N+1，V2＝V2N，.....，VN-1＝VN+1，V1>V2>.....>VN-1>VN(ii) a Or applying voltage values V to the electrode 1, the electrode 2N +1 in the electrode layers respectively1、V2、.....、V2N+1Voltage signal of, wherein V1＝V2N+1，V2＝V2N，.....，VN-1＝VN+1，VN>VN-1>.....>V2>V1。
7. A driving method of a display device including the display panel according to any one of claims 1 to 3, the driving method comprising:
determining the relative positions of the eyes of the user and the display panel;
determining the light emitting direction of each sub-pixel on the display panel according to the relative position;
and adjusting the grating period of each sub-pixel according to the light emergent direction.
8. The driving method according to claim 7, wherein adjusting the grating period of each sub-pixel according to the light emitting direction comprises:
determining the grating period of each sub-pixel according to the light emitting direction of each sub-pixel on the display panel;
and applying a voltage signal to an electrode layer of the display panel according to the grating period of each sub-pixel, and adjusting the grating period of the liquid crystal grating in each sub-pixel.
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