CN109307903B - Backlight source for emitting polarized light, preparation method thereof and liquid crystal display device - Google Patents
Backlight source for emitting polarized light, preparation method thereof and liquid crystal display device Download PDFInfo
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- CN109307903B CN109307903B CN201710631969.2A CN201710631969A CN109307903B CN 109307903 B CN109307903 B CN 109307903B CN 201710631969 A CN201710631969 A CN 201710631969A CN 109307903 B CN109307903 B CN 109307903B
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
- G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
- G02B6/0033—Means for improving the coupling-out of light from the light guide
- G02B6/0056—Means for improving the coupling-out of light from the light guide for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
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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
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/13362—Illuminating devices providing polarized light, e.g. by converting a polarisation component into another one
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
- G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
- G02B6/0033—Means for improving the coupling-out of light from the light guide
- G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
- G02B6/0038—Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
- G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
- G02B6/0033—Means for improving the coupling-out of light from the light guide
- G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
- G02B6/0055—Reflecting element, sheet or layer
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
- G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
- G02B6/0066—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
- G02B6/0068—Arrangements of plural sources, e.g. multi-colour light sources
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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
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133528—Polarisers
- G02F1/133536—Reflective polarizers
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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
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133528—Polarisers
- G02F1/13355—Polarising beam splitters [PBS]
Abstract
A backlight source for emitting polarized light, a preparation method thereof and a liquid crystal display device are provided. The backlight includes: a light source; the light source faces the light inlet face, and natural light emitted by the light source enters the polarized light guide plate through the light inlet face and is emitted from the light outlet face in a polarized light mode; a light correcting layer disposed over the polarized light guide plate substantially dimensionally coincident with the polarized light guide plate, wherein the light correcting layer is composed of an isotropic material; and a low refractive index layer disposed between the polarized light guide plate and the light ray correction layer. The backlight source can flexibly control the distribution direction of the emergent polarized light, improve the light-emitting efficiency, increase the flexibility of material selection, simplify the manufacturing process of the backlight source and reduce the production cost.
Description
Technical Field
The present invention relates to a liquid crystal display device, and more particularly, to a backlight for emitting polarized light.
Background
Flat panel displays, such as Liquid Crystal Displays (LCDs), are essential components of many types of electronic devices. One type of liquid crystal display, which is a passive type light emitting device, relies on a backlight at the back of the display screen to illuminate the screen. Due to the display requirements of liquid crystal flat panel displays, the light rays that are effectively utilized are light of a particular polarization direction. For a traditional backlight source emitting natural light, the utilization rate of final light intensity is often less than 5% of the original light intensity, and the light loss is very high. If the lost light is not recycled, it may cause adverse effects such as temperature rise.
One solution is to add a reflective polarizing film (e.g., DBEF from 3M company) between the natural light backlight and the lcd panel to reflect the unused polarized light back into the backlight for recycling. The film is characterized by a transmissive function for light of one polarization and a reflective function for light of the other polarization perpendicular thereto. The reflected light re-enters the light guide plate of the backlight and, after depolarization, is partially converted to the useable polarization state, thereby increasing the on-axis brightness by about 60%.
The other solution is to directly use a backlight source capable of emitting polarized light, and combine the reflective or scattering type polarizing film to achieve the effect of improving the light utilization rate. In this solution, polarization separation techniques are used directly in the backlight structure, with polarization dependent total reflection, scattering, and coating of liquid crystal layers with optical anisotropy, to achieve the goal of emitting polarized light. The backlight system as disclosed in US5729311A comprises a specially designed light guide layer into which unpolarized light is coupled via a side section of the light guide and propagates onwards. The optical waveguide is provided with a cavity filled with an optically anisotropic material. The waveguide material having a refractive index npRefractive index of optically anisotropic material noAnd ne. To meet the requirement of polarization state separation, noOr neIs equal to or substantially equal to np. However, this structure has a disadvantage in that the difficulty in filling the cavity with materials, for example, in the manufacturing process, and the difficulty in processing the waveguide plate itself due to the special requirements of the cavity structure increase, resulting in high manufacturing costs.
Patent CN100564998C ameliorates the problems involved in US5729311A and based thereon provides a backlight having a layered structure with a polarization separating film layer separate from the light guide plate. However, since the polarized light exit mechanism is total reflection and the exiting light needs to satisfy a certain angle requirement (for example, the exiting light needs to be in the vicinity of the normal), the size, shape and material of the microstructure are greatly limited.
In addition, although the structure of the existing polarized light backlight overcomes the characteristic of wide outgoing angle distribution, after the polarization separation layer is determined, the outgoing angle distribution is determined accordingly, and modulation is difficult to perform. Thus, the selectivity of the structure to be fabricated and the range of materials to be selected are limited.
Therefore, it is desirable to provide a backlight source capable of emitting polarized light, improving the light utilization rate, and flexibly controlling the distribution directions of incident and emitted polarized light, thereby further simplifying the manufacturing process, reducing the cost, and improving the efficiency.
Disclosure of Invention
To meet the above requirement, the present invention provides a backlight capable of emitting polarized light, including: the light source, polarisation light guide plate is configured with into plain noodles and goes out the plain noodles, go into the plain noodles with it links to each other to go out the plain noodles, wherein, the light source orientation go into the plain noodles, and the natural light that the light source sent passes through go into the plain noodles and get into the polarisation light guide plate, follow with the mode of polarized light go out the plain noodles and jet out, and the layer is corrected to light, the layer is corrected to light with polarisation light guide plate is size unanimous ground basically and is set up on the polarisation light guide plate, wherein the layer is corrected to light comprises isotropic material to and low refracting index layer, low refracting index layer is set up the polarisation light guide plate. In an alternative embodiment, the backlight further includes a light source adjusting layer disposed between the light incident surface of the polarized light guide plate and the light source. In a preferred embodiment, the refractive index of the light-correcting layer is between 1.40 and 1.65. In a preferred embodiment, the low refractive index layer may be an air layer.
In a preferred embodiment, the surface of the light ray correction layer away from the polarized light guide plate is provided with oblique triangular prism structures arranged in parallel, wherein the oblique triangular prism structures extend in a direction parallel to the light incident surface. In an optional embodiment, the surface of the light ray correction layer close to the polarized light guide plate is further provided with a groove structure extending in a direction perpendicular to the light incident surface. In a preferred embodiment, the cross-section of the groove structure is in the shape of a wave or an isosceles triangle.
In another alternative embodiment, the light guide plate may further comprise an additional light ray correction layer disposed on the light ray correction layer or between the light ray correction layer and the low refractive index layer substantially in size correspondence with the polarized light guide plate, wherein a surface of the additional light ray correction layer remote from the polarized light guide plate is provided with equi-spaced and parallel arranged isosceles triangle prism structures extending in a direction perpendicular to the light incident surface. In a preferred embodiment, the base angles of the isosceles triangular prism structures may vary between 35 and 50 degrees.
In a further preferred embodiment, the ratio of the distance between adjacent apex angles of the prismatic structures to the length of the base of the prismatic structures may vary between 1 and 2.
In a preferred embodiment, the polarized light guide plate includes: the upper surface of basic unit have along with polarisation light guide plate go into the miniature prism structure that the plain noodles parallel direction extends to and the birefringent layer, the lower surface on birefringent layer with the upper surface seamless close coupling of basic unit, the upper surface on birefringent layer is smooth surface basically, the optical axis direction on birefringent layer is on a parallel with the extending direction of miniature prism structure basically, wherein, the refracting index of basic unit with the ordinary ray refracting index on birefringent layer is on a basic level. In an alternative embodiment, the polarized light guide plate further includes a support layer disposed under the lower surface of the base layer, the support layer having a refractive index between 1.45 and 1.65. In a preferred embodiment, the birefringent layer is a liquid crystal layer. In a further preferred embodiment, the difference in refractive index between the extraordinary and ordinary rays of the liquid crystal layer is between 0.1 and 0.35. In another preferred embodiment, the thickness of the base layer may vary.
In a preferred embodiment, a surface of the light source adjusting layer close to the light source is provided with prism structures arranged in parallel, wherein the prism structures extend in a direction parallel to the light exit surface of the polarized light guide plate. In preferred embodiments, any base angle of the prismatic structure may vary between 0 and 90 degrees (including 90 degrees). In an alternative embodiment, the prismatic structures are arranged equidistantly and the ratio of the distance between adjacent apex angles of the prismatic structures to the length of the base edge of the prismatic structures may vary from 1 to 2. In another alternative embodiment, the prismatic structure is a fresnel lens structure.
In an optional implementation scheme, the surface of the light source adjusting layer close to the light source is provided with protruding structures extending in a direction perpendicular to the light exit surface of the polarized light guide plate and arranged in parallel, and the cross section of the protruding structures is in a shape of a light cup.
In a preferred embodiment, a method for preparing the backlight source is disclosed, which comprises independently forming the polarized light guide plate, the light source, the light correction layer and the low refractive index layer, and then combining them in a splicing manner, wherein the splicing comprises firstly arranging the low refractive index layer and the light correction layer on the light emergent surface of the polarized light guide plate, the low refractive index layer is arranged between the light correction layer and the polarized light guide plate, and the light source is arranged on the light incident surface of the polarized light guide plate, wherein the splicing manner comprises laminating. In an alternative embodiment, the method further comprises: the light source adjusting layer is independently formed and disposed between the light source and the polarized light guide plate.
In a preferred embodiment, a liquid crystal display device is disclosed, which comprises a liquid crystal display panel and the backlight source, wherein the liquid crystal display panel is arranged on the light-emitting surface side of the backlight source, and the transmission axis of a polarizer on the side of the liquid crystal display panel close to the backlight source is substantially parallel to the polarization direction of the light emitted by the backlight source.
The backlight disclosed by the invention can emit polarized light, improve the light utilization rate of the backlight, and adjust the angle distribution of polarized emergent light from the polarization separation layer by using the light ray correction layer, so that the direction of the polarized light is symmetrically distributed along the normal line, the manufacturing complexity of the polarization separation layer is greatly reduced, and the material selection range of the polarization separation layer is widened. The invention further utilizes the light source adjusting layer to adjust the incident light angle distribution, thereby further improving the utilization rate of the incident light. In addition, each part of the invention can be independently manufactured and flexibly assembled, thereby further simplifying the manufacturing process of the backlight source, reducing the cost and improving the efficiency.
Drawings
The invention may be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, in which:
fig. 1 is a schematic diagram of a backlight according to an embodiment of the invention.
Fig. 2 is a schematic diagram of the principle of operation of a backlight according to an embodiment of the invention.
Fig. 3 is a schematic structural view of a light ray correcting layer according to an embodiment of the present invention.
Fig. 4 is a cross-sectional view of the structure of fig. 3 and a schematic diagram of the operation thereof.
FIG. 5 is a schematic cross-sectional view of a light-correcting layer according to an embodiment of the invention.
FIG. 6 is a schematic diagram of an additional light-correcting layer according to an embodiment of the present invention.
Fig. 7 is a cross-sectional view of the structure of fig. 6 and a schematic diagram of the operation thereof.
Fig. 8 is a schematic view illustrating the structure and operation of a polarized light guide plate according to an embodiment of the present invention.
Fig. 9 is a schematic view of the principle of adjusting the light extraction intensity by changing the thickness of the base layer.
Fig. 10 is a schematic structural view of a polarized light guide plate including a support layer according to an embodiment of the present invention.
Fig. 11 is a schematic diagram of a backlight according to an embodiment of the invention.
Fig. 12 is a schematic diagram of the working principle of a light source regulation layer according to an embodiment of the present invention.
Fig. 13 is a schematic cross-sectional view of a light source adjustment layer according to an embodiment of the invention.
FIG. 14 is a top view and schematic structure of a light source conditioning layer according to an embodiment of the invention.
Fig. 15 is a schematic diagram of a method of splicing layers according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form. In this regard, the illustrated example embodiments are provided for purposes of illustration only and are not intended to be limiting of the invention. Therefore, it is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.
Referring first to fig. 1, there is shown a backlight for emitting polarized light according to an embodiment of the present invention, which may include a light source 100, a polarized light guide plate 200 for guiding light to propagate and converting natural light emitted from the light source 100 into polarized light, a light-correcting layer 300 having a function of correcting an emitting direction of the polarized light, and a low refractive index layer 400 between the polarized light guide plate 200 and the light-correcting layer 300. The polarized light guide plate 200, the light correcting layer 300, and the low refractive index layer 400 are stacked in parallel so as to have substantially the same size. The low refractive index layer 400 is used to space the polarized light guide plate 200 and the light correction layer 300, so that the incident light converted into polarized light in the polarized light guide plate 200 can be coupled out from the light-emitting surface of the polarized light guide plate 200. The low refractive index layer 400 may be an air layer, and the thickness thereof may be adjusted, for example, using a spacer to adjust the thickness of the low refractive index layer 400.
As shown in fig. 2, the polarized light guide plate 200 has an incident surface 201, an exit surface connected to the incident surface 201, and a side surface 202 connected to the exit surface and opposite to the incident surface 201. The light source 100 is disposed toward the light incident surface 201. The light emitted from the light source 100 enters the polarized light guide plate 200 from the light incident surface 201 of the polarized light guide plate 200, and is continuously and alternately reflected on the upper and lower surfaces thereof, and propagates in the form of a waveguide. During the propagation, the optical waveguide interacts with the internal structure (described in detail below) of the polarized light guide plate 200, s-polarized light therein is separated with a certain probability to exit from the light exit surface (upper surface) of the polarized light guide plate 200, and p-polarized light keeps the waveguide mode to propagate forward, and part of the p-polarized light is converted into s-polarized light to exit. Light that cannot be emitted leaks from the side surface 202 of the polarized light guide plate 200. In general, the exit direction of s-polarized light exiting from the upper surface of the polarized light guide plate 200 does not necessarily exhibit a symmetrical distribution along the normal of the upper surface, such as the light rays 211 and 212 in fig. 2, depending on the internal structure and material of the polarized light guide plate 200. In the application of a typical backlight, the emergent light is required to be symmetrically distributed along the normal of the emergent light surface of the backlight, which requires that the internal structure and material of the polarized light guide plate 200 must be optimized, resulting in limitations on the structure and material selected for the polarized light guide plate 200. The light correcting layer 300 is used to correct the oblique distribution of the light rays 211 and 212 to the normal symmetric distribution, such as the light rays 311 and 312. Meanwhile, the light correction layer 300 is made of an isotropic material, so that the polarization characteristics of the transmitted light can be maintained while the direction of the light is corrected, that is, the polarization directions of the light 311 and 312 and the light 211 and 212 are the same and are both s-polarized, thereby ensuring the polarization of the light emitted by the backlight source. The refractive index of the light-correcting layer is between 1.40 and 1.65, and the light transmittance of the light-correcting layer is more than 90 percent.
In one embodiment, the top surface of the light-correcting layer 300 has parallel and equidistant prism structures extending in a direction parallel to the light-incident surface 201, as shown in FIG. 3. The height of the prismatic structures is 5 to 50 microns. As shown in fig. 4, the light ray 321, 322, 323 or 324 entering the light correction layer 300 is refracted or totally reflected at the surface of the prism, refracted again, and then emitted from the surface of the prism, thereby forming an outgoing light ray 331, 332, 333 or 334 having a new direction. The cross section of the prism isThe oblique triangle can convert the obliquely distributed incident lights 211 and 212 into the symmetrically distributed emergent lights 311 and 312 by adjusting two base angles of the oblique triangle. The degree of the right and left base angles of the oblique triangular prism depends on the degree of inclination of the incident polarized light entering the light ray correction layer 300, that is, the degree of inclination of the polarized light exiting the polarized light guide plate 200, and further, depends on the structure and material of the polarized light guide plate 200. In a preferred embodiment, the distance L between the apex angles of two adjacent prisms1And the length L of the bottom edge of the prism2The ratio of (a) may vary within the range of 1 to 2.
In an alternative embodiment, the lower surface of the light-correcting layer 300 has a groove structure that is parallel and equidistant and extends along a direction perpendicular to the light incident surface 201, as shown in fig. 5. The cross section of the groove structure may be wavy, as shown in fig. 5, or isosceles triangle, which is used to make the total light intensity of the polarized light emitted from the polarized light guide plate 200 uniform in the transverse direction (the direction perpendicular to the extending direction of the groove). For a wavy groove structure, the distance L between the crest and the trough3And the distance L between adjacent peaks or troughs4Not greater than 100 microns.
In another embodiment, in addition to the light correcting layer 300, another light correcting layer 300a is included. The upper surface of the light-straightening layer 300a has parallel and equidistant prism structures extending along a direction perpendicular to the light-incident surface 201, as shown in fig. 6. The cross section of the prism is an isosceles triangle, and the base angle can be changed from 35 degrees to 50 degrees. The height of the isosceles triangle is 5 to 50 microns, and the distance L between the vertex angles of two adjacent prisms5And the length L of the bottom edge of the prism6The ratio of (a) may vary within the range of 1 to 2. The light ray correcting layer 300a may be disposed on the upper layer of the light ray correcting layer 300, or may be disposed between the light ray correcting layer 300 and the low refractive index layer 400. As shown in fig. 7, the light-correcting layer 300a can combine the incident light with large angle diverging in the lateral direction into the emergent light with small angle, so as to improve the light intensity distribution of the backlight source on the front side.
In another embodiment, as shown in FIG. 8, the polarized light guide plate 200 may include a base layer 203 and a birefringenceAnd an emitting layer 204 having a micro-prism structure extending in a direction parallel to the incident surface 201 of the polarized light guide plate 200 on an upper surface of the base layer 203 to which the birefringent layer 204 is tightly coupled. The surface of the birefringent layer 204 remote from the base layer is a substantially smooth surface. The birefringent layer 204 is composed of a material having birefringence and having a refractive index n of ordinary raysoAnd refractive index n of extraordinary rayseAnd n iseGreater than no. The optical axis direction of the birefringent layer 204 is substantially parallel to the extending direction of the micro-prism structures on the base layer 203, so that the refractive index difference Δ n of the birefringent layer 204 is maximized in the direction orthogonal to the extending direction, thereby improving the efficiency of polarization separation. In a preferred embodiment, the birefringent layer 204 is a liquid crystal layer with an extraordinary refractive index neAnd ordinary ray refractive index noThe difference Δ n is between 0.1 and 0.35. The base layer 203 is composed of an isotropic homogeneous medium having a refractive index n equal to the ordinary refractive index n of the birefringent layer 204oSubstantially identical. Due to the presence of the birefringent layer 204, the s-polarized light and the p-polarized light have different optical paths inside the polarized light guide plate 200. For example, for the s-polarized light 221, there is total reflection at the interface between the micro prism and the birefringent layer 204, and the light after total reflection enters the outgoing angle range, so that it no longer satisfies the waveguide mode and exits from the upper surface of the polarized light guide plate 200. For the p-polarized light ray 222, since the refractive indexes thereof in the base layer 203 and the birefringent layer 204 are substantially the same, there is no total reflection at the interface thereof, and the original direction can be maintained to continue propagating in the form of a waveguide without being emitted from the upper surface of the polarized light guide plate 200, thereby realizing the characteristic of polarization separation and selectively emitting s-polarized light. The p-polarized light propagating in the form of a waveguide is partially converted into s-polarized light by scattering or optical rotation during propagation, and thus can be redirected to exit from the upper surface. In a preferred embodiment, the thickness L of the base layer 2037Can be adjusted so as to adjust the intensity of the polarized light emitted from the light-emitting surface. As shown in FIG. 9, light incident in the direction 113 is constantly reflected within the substrate 203 by the waveguide mode, and s-polarized light is reflected and propagated by the microprism structure of the upper surface of the substrate 203And the light is emitted from the light-emitting surface after the direction is changed. When the thickness of the base layer 203 is reduced, the number of times of reflection of the light incident in the same direction 113 in the same propagation length is increased, so that the chance of contact with the micro-prism structure is increased, the chance of emergent light from the light emergent surface is increased, and the effect of enhancing the light emergent intensity is achieved. In a preferred embodiment, the thickness of the base layer 203 should be no less than the height of the light source 100, so that the incident light emitted from the light source 100 can enter the base layer 203 entirely. In a preferred embodiment, the height of the microprismatic structures of the base layer 203 is no greater than 100 microns and the thickness of the birefringent layer 204 is no less than the height of the microprismatic structures such that the microprismatic structures are entirely contained within the birefringent layer 204.
In an alternative embodiment, the polarized light guide plate 200 may further include a support layer 205. As shown in fig. 10, the upper surface of the support layer 205 is closely bonded to the lower surface of the base layer 203, and the size of the contact surface thereof is substantially uniform. The support layer 205 may be composed of an isotropic, homogeneous material with a refractive index between 1.45 and 1.65; it may also consist of a material with a certain birefringence, such as a PET material, in which p-polarized light is continuously optically rotated while propagating, effecting a conversion of p-polarization into s-polarization.
The distribution direction of the light exiting from the polarized light guide plate 200 depends on the refractive index difference Δ n of the birefringent layer 204 and the shape of the microstructure on the inner surface of the base layer 203. For the arranged microstructure and the optimized birefringent material, the light emitted from the polarized light guide plate 200 is symmetrically distributed along the normal direction of the light emitting surface. Otherwise, the distribution direction of the outgoing light is inclined, thereby limiting the choice of birefringent material. By adding the light correction layer 300, the distribution direction of emergent light is corrected and symmetrically distributed in the normal direction, so that the limitation of materials is reduced, and the cost is reduced.
In another embodiment, the backlight may further include a light source adjustment layer 500. As shown in fig. 11, the light source adjusting layer 500 is disposed between the light source 100 and the polarized light guide plate 200, and has a size substantially identical to the light incident surface of the light source 100 and the polarized light guide plate 200. The light emitted from the general light source 100, such as an LED light source, has a specific light distribution curve, and the light emitted from the light source 100 is classified into a small-angle light 111 and a large-angle light 112 according to the angle between the light and the coordinate axis, wherein the distribution direction of the small-angle light 111 is close to the normal direction of the light emitting surface of the light source 100, and the distribution direction of the large-angle light 112 is deviated from the normal direction of the light emitting surface of the light source 100, as shown in fig. 12. After the light rays 111 and 112 enter the polarized light guide plate 200, propagate in a waveguide mode and interact with the birefringent layer 204, the large-angle light ray 112 meets the exit condition of the polarized light guide plate 200 and exits from the exit surface; the small-angle light rays 111 cannot satisfy the emission conditions of the polarized light guide plate 200, continue to propagate in the waveguide mode, and finally leak from the side surface 202 opposite to the light incident surface 201 of the polarized light guide plate 200. For a typical light source, the high angle rays 112 that can meet the final exit condition are only 30% or less of the total amount of rays. The light source adjusting layer 500 can readjust the light emitted from the light source 100 to convert part of the small-angle light rays 111 into the large-angle light rays 512, so that the proportion of the large-angle light rays 512 is increased, the light coupled and emitted from the light-emitting surface of the polarized light guide plate 200 is increased, and the light intensity of the backlight source is enhanced. The portion of small angle light 511 that is not modified may still leak out of side 202. In a preferred embodiment, the ratio of the large-angle light to the total amount of light may be increased to 60% or more after passing through the light source adjustment layer 500.
As shown in fig. 13 (a), the light source adjustment layer 500 has prism structures arranged in parallel at the light incident surface, and the prism structures extend in a direction parallel to the light emitting surface of the polarized light guide plate 200. The height of the prisms is 5 to 50 microns. The small-angle light entering the light source adjusting layer 500 is refracted twice with the surface of the prism and the right plane, so that an outward deflection effect is generated, and a large-angle light deviating from the normal direction is formed. The prismatic structures may be isosceles or rhomboid and the two base angles may vary from 0 to 90 degrees, including 90 degrees. In an alternative embodiment, the prisms are arranged equidistantly, as shown in (b) of fig. 13, and the distance L between the vertex angles of two adjacent prisms8And the length L of the bottom edge of the prism9The ratio of (a) may vary within the range of 1 to 2. In another alternative embodiment, as shown in (c) of fig. 13, the prism structure is a fresnel structureA lens structure.
In another alternative embodiment, the light source adjusting layer 500 has parallel convex structures on the light incident surface, but the convex structures extend in a direction perpendicular to the light emitting surface of the polarized light guide plate 200, as shown in the left top view of fig. 14. The cross section of the convex structure is in a light cup shape. The chassis size of the light cup matches the size of the LED chip in the light source 100. The light entering through the light incident surface of the light source adjusting layer 500 is reflected by the light incident surface and then emitted to the side surface of the light cup at a large angle in the transverse direction, so that the light entering the polarized light guide plate is narrowed in the transverse direction. The shape of the wall of the light cup can be a conical curve, a straight line or a broken line connected end to end.
In another embodiment, a method of making the above-described backlight is disclosed, comprising separately forming the light source 100, the polarized light guide plate 200, the light-correcting layer 300, and the low refractive index layer 400, and then combining them in a tiled fashion to form the backlight. As shown in fig. 15 (a), the light-correcting layer 300 and the low refractive index layer 400 are spliced on the light-emitting surface of the polarized light guide plate 200, and the low refractive index layer 400 is located between the light-correcting layer 300 and the polarized light guide plate 200; the light source 100 is spliced to the light incident surface of the polarized light guide plate 200. In a preferred embodiment, the low refractive index layer 400 is an air layer, and the light correction layer 300 and the polarized light guide plate 200 are not closely attached to each other but form an air layer, and the thickness of the air layer may be controlled by adding spacers. The light source 100 and the polarized light guide plate 200 may not be tightly attached, and an air gap is left between the two adjacent layers. In an alternative embodiment, the method of manufacturing a backlight further includes separately forming a light source adjustment layer 500, and splicing the light source adjustment layer 500 between the light source 100 and the polarized light guide plate 200, as shown in (b) of fig. 15. The light source adjusting layer 500 may be attached to the light incident surface of the polarized light guide plate 200 by glue 600, and then the light source 100 is spliced to the light source adjusting layer 500 by the above method.
In another embodiment of the present invention, a liquid crystal display device is provided, which includes the backlight source of any one of the above embodiments and a liquid crystal display panel, wherein the liquid crystal display panel is disposed on the light-emitting surface side of the backlight source, and the transmission axis of a polarizer on the side of the liquid crystal display panel close to the backlight source is substantially parallel to the polarization direction of the light emitted from the backlight source. Therefore, the light provided by the backlight source is linearly polarized light with a specific polarization direction, and when the light passes through the lower polarizer in the liquid crystal display panel, the light has high transmittance due to the fact that the polarization direction of the light is consistent with the transmission axis of the lower polarizer, and the light can pass by 100% under an ideal condition, so that the light utilization rate of the backlight source is improved, and energy consumption is saved. Meanwhile, due to the fact that the intensity and the angle distribution of emergent light of the backlight source are designed, the final display light intensity is uniform, the display light angle is controllable, and the display effect is good.
Although several exemplary embodiments have been described above in detail, the disclosed embodiments are merely exemplary and not limiting, and those skilled in the art will readily appreciate that many other modifications, adaptations, and/or alternatives are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of the present disclosure. Accordingly, all such modifications, adaptations, and/or alternatives are intended to be included within the scope of the present disclosure as defined by the following claims.
Claims (24)
1. A backlight that emits polarized light, the backlight comprising:
a light source;
the light source faces the light inlet face, and natural light emitted by the light source enters the polarized light guide plate through the light inlet face and is emitted from the light outlet face in a polarized light mode;
a light-correcting layer disposed over the polarized light guide plate in conformity with the size of the polarized light guide plate, wherein the light-correcting layer is composed of an isotropic material; and
a low refractive index layer disposed between the polarized light guide plate and the light ray correction layer;
the surface of the light ray correction layer, which is far away from the polarized light guide plate, is provided with oblique triangular prism structures which are arranged in parallel, and the oblique triangular prism structures extend along the direction parallel to the light incident surface;
wherein the polarized light guide plate includes:
the upper surface of the base layer is provided with a micro prism structure, and the extending direction of the micro prism structure is parallel to the light incident surface of the polarized light guide plate; and
the lower surface of the birefringent layer is seamlessly and tightly combined with the upper surface of the base layer, the upper surface of the birefringent layer is a smooth surface, the optical axis direction of the birefringent layer is parallel to the extending direction of the micro prism structure,
wherein the refractive index of the base layer is consistent with the ordinary ray refractive index of the birefringent layer.
2. The backlight of claim 1, wherein the backlight further comprises a light source adjustment layer disposed between the light-in surface of the polarized light guide plate and the light source.
3. The backlight source as claimed in claim 1, wherein the surface of the light-correcting layer adjacent to the polarized-light guide plate is further provided with groove structures, and the groove structures extend along a direction perpendicular to the light incident surface.
4. The backlight of claim 3, wherein the groove structures have a wave-shaped cross-section.
5. The backlight of claim 3, wherein the groove structures have a cross-section of an isosceles triangle.
6. The backlight of claim 1, wherein the backlight further comprises an additional light correction layer disposed over the light correction layer or between the light correction layer and the low refractive index layer in conformity with the dimensions of the polarized light guide plate, wherein a surface of the additional light correction layer remote from the polarized light guide plate is provided with equi-spaced and parallel arranged isosceles triangular prism structures extending in a direction perpendicular to the light incident surface.
7. The backlight of claim 6, wherein the base angles of the isosceles triangular prism structures can vary between 35 degrees and 50 degrees.
8. The backlight of claim 6, wherein a ratio of a distance between adjacent apex angles of the isosceles triangular prism structures to a length of a base of the isosceles triangular prism structures can vary between 1 and 2.
9. The backlight of claim 1 or 2, wherein the refractive index of the light correcting layer is between 1.40 and 1.65.
10. The backlight of claim 1, wherein the birefringent layer is a liquid crystal layer.
11. The backlight of claim 10, wherein the refractive index difference between the extraordinary and ordinary rays of the liquid crystal layer is between 0.1 and 0.35.
12. The backlight of claim 1, wherein the base layer is variable in thickness.
13. The backlight of claim 1, wherein the polarized light guide plate further comprises a support layer disposed below a lower surface of the base layer, the support layer having a refractive index between 1.45 and 1.65.
14. The backlight source as claimed in claim 2, wherein the surface of the light source adjusting layer adjacent to the light source is provided with parallel arranged prism structures, and the prism structures of the light source adjusting layer extend along a direction parallel to the light exit surface of the polarized light guide plate.
15. The backlight of claim 14, wherein any base angle of the prismatic structures of the light source modification layer can vary within a range of no greater than 90 degrees.
16. The backlight of claim 15, wherein the prismatic structures of the light source adjustment layer are arranged equidistantly, and the ratio of the distance between adjacent apex angles of the prismatic structures of the light source adjustment layer to the length of the base edge of the prismatic structures of the light source adjustment layer can vary from 1 to 2.
17. The backlight of claim 14, wherein the prismatic structures of the light source modification layer are fresnel lens structures.
18. The backlight source as claimed in claim 2, wherein the surface of the light source adjusting layer close to the light source is provided with parallel convex structures extending in a direction perpendicular to the light exit surface of the polarized light guide plate.
19. The backlight of claim 18, wherein the raised structures are light cup-shaped in cross-section.
20. The backlight of claim 1 or 2, wherein the low refractive index layer is a layer of air.
21. The backlight of claim 1 or 5, wherein a ratio of a distance between adjacent apex angles of the angled triangular prism structures to a length of a base of the angled triangular prism structures can vary between 1 and 2.
22. A method of making the backlight of claim 1 or 2, the method comprising:
independently forming the polarized light guide plate, the light source, the light ray correction layer and the low refractive index layer,
the light source is combined in a splicing mode, the splicing comprises the step of arranging the low refractive index layer and the light correction layer on the light emergent surface of the polarized light guide plate, the low refractive index layer is arranged between the light correction layer and the polarized light guide plate, and the light source is arranged on the light incident surface of the polarized light guide plate,
wherein, the splicing mode comprises fitting.
23. The method of claim 22, the method further comprising:
the light source adjusting layer is independently formed,
the light source adjusting layer is disposed between the light source and the polarized light guide plate.
24. A liquid crystal display device comprising a liquid crystal display panel and the backlight according to claim 1 or 2, the liquid crystal display panel being disposed on a light exit surface side of the backlight, a transmission axis of a polarizing plate on a side of the liquid crystal display panel close to the backlight being parallel to a polarization direction of light emitted from the backlight.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710631969.2A CN109307903B (en) | 2017-07-28 | 2017-07-28 | Backlight source for emitting polarized light, preparation method thereof and liquid crystal display device |
| PCT/CN2018/094520 WO2019019888A1 (en) | 2017-07-28 | 2018-07-04 | A polarizing backlight unit, method of manufacturing the same and liquid crystal display device using the same |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201710631969.2A CN109307903B (en) | 2017-07-28 | 2017-07-28 | Backlight source for emitting polarized light, preparation method thereof and liquid crystal display device |
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| CN109307903A CN109307903A (en) | 2019-02-05 |
| CN109307903B true CN109307903B (en) | 2020-05-12 |
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| WO (1) | WO2019019888A1 (en) |
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| CN111443410A (en) * | 2019-05-24 | 2020-07-24 | 宁波激智科技股份有限公司 | Sensor dimming layer and preparation method thereof |
| WO2021119882A1 (en) * | 2019-12-16 | 2021-06-24 | 重庆康佳光电技术研究院有限公司 | Display device capable of changing direction of light |
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| CN1571903A (en) * | 2001-10-04 | 2005-01-26 | 三菱丽阳株式会社 | Planar light source device and light guide therefor |
| KR20070028827A (en) * | 2005-09-08 | 2007-03-13 | 삼성전자주식회사 | Light guide unit, backlight assembly having the light guide unit and display device having the same |
| CN204882926U (en) * | 2015-08-21 | 2015-12-16 | 深圳市埃晶科技有限公司 | Light guide plate subassembly, backlight unit and display |
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| JPH10508151A (en) * | 1995-08-23 | 1998-08-04 | フィリップス エレクトロニクス ネムローゼ フェンノートシャップ | Flat-panel image display device |
| JP2001049008A (en) * | 1998-09-29 | 2001-02-20 | Teijin Ltd | Forward scattering polymer film having haze anisotropy |
| KR100905100B1 (en) * | 2001-09-26 | 2009-06-30 | 코닌클리케 필립스 일렉트로닉스 엔.브이. | Illumination arrangement arranged to receive unpolarized light and emit polarized light, and display system |
| CN100591989C (en) * | 2002-11-06 | 2010-02-24 | 夏普株式会社 | Lighting device and image display unit and light guide provided with it |
| KR100738104B1 (en) * | 2006-02-08 | 2007-07-12 | 삼성전자주식회사 | Polarized light emitting light guide plate and method for fabricating the same and illuminator for flat panel display device using the same |
| CN104316990B (en) * | 2014-11-24 | 2017-08-29 | 京东方科技集团股份有限公司 | Light guide plate and preparation method thereof, backlight module and liquid crystal display device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1571903A (en) * | 2001-10-04 | 2005-01-26 | 三菱丽阳株式会社 | Planar light source device and light guide therefor |
| KR20070028827A (en) * | 2005-09-08 | 2007-03-13 | 삼성전자주식회사 | Light guide unit, backlight assembly having the light guide unit and display device having the same |
| CN204882926U (en) * | 2015-08-21 | 2015-12-16 | 深圳市埃晶科技有限公司 | Light guide plate subassembly, backlight unit and display |
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| WO2019019888A1 (en) | 2019-01-31 |
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