WO2014187107A1

WO2014187107A1 - Light ray conversion device, backlight module and display device

Info

Publication number: WO2014187107A1
Application number: PCT/CN2013/088899
Authority: WO
Inventors: 王尚
Original assignee: 京东方科技集团股份有限公司
Priority date: 2013-05-24
Filing date: 2013-12-09
Publication date: 2014-11-27
Also published as: CN103293650B; CN103293650A

Abstract

Disclosed are a light ray conversion device, a backlight module and a display device. The light ray conversion device comprises a collimating lens (11) and a reflection module (12), wherein the collimating lens is used for collimating natural light, and converting same into linearly polarized light (31) comprising light rays perpendicular to each other in two vibration directions at the same time. An out-light surface side of the collimating lens is provided with a polarization beam splitter (13), and an incident angle of the linearly polarized light obtained by the collimating lens, which is irradiated onto the polarization beam splitter, is an acute angle. The polarization beam splitter is used for transmitting light (32) in the linearly polarized light, the vibration direction of which is the same as the direction of a transmission axis of the polarization beam splitter, and reflecting light (33) with other vibration directions. The reflection module is used for reflecting the light rays, which are reflected by the polarization beam splitter, at least twice, so as to enable the reflected light rays to be emitted in the same vibration direction as the transmitted light rays passing through the polarization beam splitter.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light conversion device, a backlight module, and a display device. BACKGROUND OF THE INVENTION Light is a transverse wave that is capable of polarization, i.e., perpendicular to the direction of light propagation and biased toward certain directions. In daily life, sunlight, light emitted by illumination, etc. are natural light, which contains all possible polarization directions of light perpendicular to the direction of light propagation.

In an existing display, such as a liquid crystal display, the light-emitting element is a Light Emitting Diode (LED), which emits light similar to natural light, and changes the point source of the LED into a surface light source through the light guide plate. However, in practical applications, liquid crystal displays need to use their internal liquid crystals to achieve brightness conversion to achieve different display effects. Among them, it is required that the light passing through the liquid crystal must be linearly polarized light (light that vibrates in a fixed direction). Can do the above. Therefore, the light-emitting side of the light guide plate of the liquid crystal display is provided with a polarizing plate, and the polarizing plate allows only the light of a specific vibration direction to pass, and the light of the other vibration direction is absorbed or reflected by the polarizing plate, thereby obtaining the above-mentioned linearly polarized light.

It can be seen from the above description that the light emitted by the LED is utilized only by the portion of the polarizing plate, and the remaining portion of the light is not utilized, thereby causing waste of the light source and reducing the utilization of the light source.

SUMMARY OF THE INVENTION Embodiments of the present invention provide a light conversion device, a backlight module, and a display device to improve utilization of a light source.

To achieve the above object, an aspect of the present invention provides a light conversion device in a display, comprising a collimating lens for collimating natural light and simultaneously converting two vibrations perpendicular to each other, and a reflection module a line polarized light of the directional light; a polarizing beam splitter is disposed on the light emitting surface side of the collimating lens, and the linear polarized light obtained by the collimating lens is irradiated to the polarizing beam splitter The light sheet transmits light of the same vibration direction through the same light transmission in the axial direction; the reflection module is configured to reflect at least two light rays reflected by the polarization beam splitter to make the reflected light and the polarized light The transmitted light of the beam splitter is emitted in the same vibration direction. The total reflection surface; the light-emitting surface of the collimating lens is in contact with the light-incident surface of the reflection module.

Preferably, the incident angle of the linearly polarized light irradiated to the polarizing beam splitter is 45 degrees.

Preferably, the incident angle of the light illuminating the total reflection surface in the reflection module is 45 degrees. For example, the total reflection surface includes a first reflection surface, a second reflection surface, a third reflection surface, and a fourth reflection surface; the light reflected by the polarization beam splitter sequentially passes through the first reflection surface and the second reflection surface After the third reflecting surface and the fourth reflecting surface are reflected, the vibration direction and the outgoing direction are the same as the vibration direction and the outgoing direction of the transmitted light.

The reflective module provided by the embodiment of the present invention has various structures. For example, the reflective module is a prism; and the polarizing beam splitter is fixed in the prism.

In order to better fix the polarizing beam splitter, a resin is fixed between the polarizing beam splitter and the prism, and one end of the resin is fixedly connected to the prism, and the other end side is fixedly connected to the polarizing beam splitter.

Wherein, in order to ensure that the transmitted light passing through the polarizing beam splitter is not affected by the resin, the refractive index of the resin is similar to the refractive index of the prism material.

There are various types of polarization beam splitters provided by the embodiments of the present invention. For example, the polarization beam splitter is a polarizing filter or a birefringent beam splitting prism of a multilayer film structure.

There are various types of collimating lenses provided by embodiments of the present invention. For example, the collimating lens is an internal total reflection collimating lens.

Another aspect of the present invention provides a backlight module including the above-described light conversion device. Yet another aspect of the present invention provides a display device including the above backlight module.

In the light conversion device, the backlight module and the display device provided by the embodiments of the present invention, since the collimating lens is provided, the scattered natural light can be concentrated into one beam, and the beam is perpendicular to each other. The linear polarization of the two vibration directions, when the linear polarized light obtained by the collimating lens is irradiated onto the polarizing beam splitter, the incident angle is an acute angle, so that the direction of light propagation in a vibration direction in the linear polarized light after the polarizing beam splitter is unchanged. In the past, it is the transmitted light, and the other direction of the light is reflected at the polarizing beam splitter, that is, the reflected light, and then the reflection of the light through the reflection module at least twice, the incident light becomes the same vibration as the transmitted light. Direction and shoot. It can be seen from the above process that the natural light passes through the collimating lens, the polarizing beam splitter and the reflecting module, and the light in the two vibration directions can finally be emitted in the same vibration direction, so that the light of different vibration directions can be utilized, thereby avoiding the waste of the light source. , improved light source utilization.

In addition, in the prior art, in order to obtain linearly polarized light, a lower polarizing plate is generally disposed on a side of the display adjacent to the light-emitting surface of the light guide plate. In contrast, in this embodiment, linearly polarized light is directly obtained by the light conversion device. There is no need to set the lower polarizing plate, which simplifies the process and saves costs. DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly described below. It is obvious that the drawings in the following description relate only to some embodiments of the present invention, rather than to the present invention. limit. FIG. 1 is a schematic diagram of a perspective view of a light conversion device according to an embodiment of the present invention; FIG.

2 is a schematic diagram of another perspective of a light conversion device according to an embodiment of the present invention; FIG. 3 is a schematic diagram of a propagation path of light in a light conversion device according to an embodiment of the present invention; FIG. 4 is a schematic diagram of a light conversion device according to an embodiment of the present invention; Schematic diagram of specific application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The technical solutions in the embodiments of the present invention will be clearly and completely described in the following with reference to the accompanying drawings.

The embodiment of the invention provides a light conversion device in a display, as shown in FIG. 1 , comprising a collimating lens 11 and a reflection module 12 . The collimator lens 11 is used to collimate natural light while converting natural light into linearly polarized light including light rays of two vibration directions perpendicular to each other. Collimating lens 11 light emitting side The polarization beam splitter 13 is provided, and the incident angle of the linearly polarized light obtained by the collimator lens 11 to the polarization beam splitter 13 is an acute angle. The polarization beam splitter 13 is for transmitting light having the same vibration direction as that of the polarization beam splitter 13 in the linearly polarized light, and reflecting light in the other vibration directions. The reflection module 12 is configured to reflect at least two rays reflected by the polarization beam splitter 13 to emit light in the same vibration direction as the transmitted light passing through the polarization beam splitter 13.

In the light conversion device of the display provided by the embodiment of the present invention, since the collimating lens is provided, the scattered natural light can be concentrated into one beam, and the beam is linearly polarized light including two vibration directions perpendicular to each other. When the linearly polarized light obtained by the collimating lens is irradiated onto the polarizing beam splitter, the incident angle is an acute angle. Therefore, after the polarizing beam splitter, the direction of light propagation in a vibrating direction is unchanged, and the transmitted light is transmitted light. A light in the direction of vibration is reflected at the polarization beam splitter, that is, reflected light, and then reflected by the reflection module at least twice, so that the direction of the reflected light becomes the same as the vibration of the transmitted light and is emitted. . It can be seen from the above process that the natural light passes through the collimating lens, the polarizing beam splitter and the reflecting module, and the light in the two vibration directions can finally be emitted in the same vibration direction, so that the light of different vibration directions can be utilized, thereby avoiding the waste of the light source. , improved light source utilization.

It should be noted here that natural light contains light in a variety of vibration directions. Then, by setting the structure of the collimating lens, the natural light is converted into a light source containing only two mutually perpendicular vibration directions by refraction in the collimating lens, and the astigmatism is concentrated into a bundle. Light. Wherein, by changing the structure of the collimating lens, such as an internal total reflection collimating lens (good collimating effect) or other structural type of lens, and its distance from the illuminating source, relative position, etc., astigmatism can be effectively avoided. Loss of light source during the convergence process to avoid wasting the light source. In addition, for two kinds of light whose vibration directions are perpendicular to each other, according to the characteristics of light, a light of a vibration direction needs to be reflected at least twice to change its vibration direction to achieve the purpose of emitting in the same vibration direction.

The linearly polarized light is a light source including two kinds of linearly polarized light whose vibration directions are perpendicular to each other. As shown in FIG. 1 , the reflection module 12 can be a prism, and the prism is provided with a total reflection surface for completely reflecting the reflected light passing through the polarization beam splitter 13; the light exit surface of the collimator lens 11 is matched with the prism entrance surface; The sheet 13 is fixed in the prism. As is known from the prior art, light is a A transverse wave with both wave-particle duality. Therefore, for the propagation of light in the air, it will be affected by other media and noise in the air, thus affecting the smoothness and accuracy of light propagation. Therefore, by setting the reflection module 12 as a prism structure and setting a specific surface of the prism as a total reflection surface, the light propagates inside the prism and emits at the total reflection surface, so that the light propagation is not interfered by other factors, thereby improving The efficiency and accuracy of light propagation, while the total reflection surface ensures that light does not lose energy after it is reflected there. Wherein, the light-emitting surface of the collimator lens 11 and the prism-incident surface are bonded to each other, that is, the light-emitting surface of the collimator lens 11 and the light-incident surface of the prism are bonded at the boundary thereof, and the lens is collimated by the collimator lens 11 The beam, that is, the linear polarized light, enters the prism directly, avoiding the loss of the light source energy due to the phenomenon of refraction and reflection at the contact surface. In addition, the polarization beam splitter 13 is fixed in the prism to ensure that the reflected light and the transmitted light after passing through the polarizing beam splitter 13 directly enter the prism and propagate. At this time, since the material of the prism is usually glass or the like, and in order to improve the propagation efficiency of light in the prism, the refractive index and transmittance of the material of the prism are large, and the polarizing beam splitter 13 is directly fixed on the surface of the prism. inconvenient. Therefore, the polarizing beam splitter 13 can be fixed by using a resin having a refractive index close to that of the prism material. Specifically, as shown in FIG. 1, the resin 14 can be fixedly disposed between the polarizing beam splitter 13 and the prism, and the structure of the resin 14 conforms to the polarization. The beam splitter 13 has a structure in which one end side is fixedly connected to the prism and the other end side is fixedly connected to the polarization beam splitter 13. Here, one end side of the polarization beam splitter 13 is fixed to the resin 14, and the other end side is directly bonded to the surface of the prism, so that the linearly polarized light is directly irradiated from the prism onto the polarization beam splitter 13, and no light source loss occurs. Of course, it is also possible to provide the resin 14 on both end sides of the polarization beam splitter 13 to ensure a better fixing effect. At this time, the linearly polarized light is emitted from the prism, enters the resin 14, and is emitted from the resin 14 into the polarizing beam splitter 13. The reflected light passing through the polarizing beam splitter 13 needs to enter the prism through the resin 14 again, which tends to cause a change in the direction of the light, which causes loss of energy and low practicability. The refractive index of the resin 14 is similar to the refractive index of the material of the prism, so that the resin is approximately equivalent to a part of the prism, avoiding excessive refraction of the light at the boundary, resulting in loss of transmitted light energy and non-directionality of the propagation direction.

It should be noted that the prism may be a unitary structure, and a fixing groove for fixing the resin and the polarization beam splitter may be opened therein. Of course, the prism may also be composed of two parts and bonded by resin. Set together, a resin and a polarizing beam splitter are disposed between the above two portions.

When the prism is not used, the light is propagated in the air, and the transmitting module 12 can be a structure including a plurality of total reflection panels, and the plurality of total reflection panels are fixedly connected through the frame.

The light ray includes two vibration directions perpendicular to each other (vertical direction and horizontal direction), and the polarizing beam splitter allows the light vibrating in the vertical direction to pass through, for example, when the linearly polarized light is irradiated onto the polarizing beam splitter 13, the light vibrating in the vertical direction Transmitted in the past, and the direction of propagation does not change, and finally is emitted from the prism; the light vibrating in the horizontal direction is reflected at the polarization beam splitter 13, and the incident angle of the polarizing beam splitter 13 is 45 degrees by the line polarized light. The angle between the transmitted light and the reflected light is 90 degrees, and the energy of the two rays is equal, so that the finally emitted light has the same direction of vibration. The two beams of equal energy increase the brightness and uniformity of the emitted light.

As mentioned in the above embodiment, for two kinds of lights whose vibration directions are perpendicular to each other, the vibration direction of the two kinds of lights can be made uniform after at least two reflections. The light that is reflected in this embodiment may be determined according to actual conditions. For example, when the liquid crystal panel in the liquid crystal display requires linearly polarized light that vibrates in the vertical direction, when the polarizing beam splitter 13 allows the light to vibrate in the vertical direction, it is necessary to reflect the reflected light of the horizontal vibration to change the vibration direction. On the other hand, when the polarization beam splitter 13 allows the light to be vibrated in the horizontal direction, it is necessary to change the type of the light in the vibration direction, depending on the requirements of the liquid crystal panel in the liquid crystal panel and the specific structure of the polarization beam splitter 13.

In Fig. 1, the total reflection is reflected by the light reflected by the polarization beam splitter 13, and its specific structure is as shown in Fig. 2. The total reflection surface may include a first reflection surface 121, a second reflection surface 122, a third reflection surface 123, and a fourth reflection surface 124. The polarization beam splitter 13 and the resin 14 are not shown in Fig. 2 due to the viewing angle problem. The specific working process is shown in FIG. 3 and explained in conjunction with FIG. 2 . The linearly polarized light 31 (shown by the thick solid arrow in Fig. 3) obtained by the collimator lens 11 first enters the prism, and then is irradiated onto the polarizing beam splitter 13 to be divided into two beams of the same transmitted light 32 (the thin solid arrow in Fig. 3) Shown) and reflected light 33 (shown by the dashed arrow in Figure 3). The transmitted light 32 continues to propagate in the prism and exits, while the reflected light 33 propagates through the prism and illuminates the first reflective surface 121. The first reflecting surface 121 is correspondingly provided with the second reflecting surface 122 in the vertical direction, and the light passing through the first reflecting surface 121 is irradiated onto the second reflecting surface 122 and reflected. Thereafter, the light is irradiated onto the third reflecting surface 123 which is disposed on the same horizontal plane as the second reflecting surface 122 and intersects and is reflected. Subsequently, the light is irradiated onto the fourth reflecting surface 124 disposed corresponding to the vertical direction of the third reflecting surface 123 and reflected, and finally emitted from the prism. Among them, the incident angle of the light irradiated onto each of the reflecting surfaces is 45 degrees, which can be used for the processing of the prism, and can conveniently control the exiting position of the reflected light. In Fig. 3, the reflected light is reflected four times, and finally, the reflected light and the transmitted light are horizontally and in the same direction, and the vibration directions and energy of the two are the same, thereby improving the uniformity of the emitted light as a whole.

It should be noted here that the total reflection surface is disposed inside the prism, and the broken line in Fig. 3 indicates the total reflection surface structure that cannot be directly viewed from the angle of view. In addition, for reflected light, the vibration of the transmitted light is the same as the direction of propagation of the respective light rays. Specifically, the vibration of the vertical direction and the vibration of the horizontal direction are defined by the propagation directions of the respective light rays. The reflected light may not be emitted in the same direction as the transmitted light, but at this time, the utilization of light energy is lower than that in the present embodiment, and the utility is poor. Here, for the structure of the total reflection surface, the structure shown in Figs. 1 to 3 is only a structure which is easy to manufacture, and of course, it may be another structure capable of realizing the above operation.

In the light conversion device described in the above embodiment, the structure may be, for example, as shown in Fig. 4 in actual use. The present invention also provides a backlight module including a light guide plate 41 and the above-described light conversion device 42. The light conversion device 42 is placed on the light incident side of the light guide plate 41, which can improve the utilization of light energy and facilitate display of the display. The structure in Figure 4 is a side-lit backlight. Of course, a direct type backlight can also be used, that is, the light source is located on the lower surface of the light guide plate 41 in FIG. When the light conversion device 42 is used at this time, the emitted light is refracted in the light guide plate 41, and the vibration direction of the emitted light is changed and the energy is lost. Therefore, when a direct type backlight is used, it is not necessary to provide the light guide plate 41, and the emitted light can be directly irradiated onto the liquid crystal panel. In this case, it is necessary to increase the area of the prism exit surface. The polarizing beam splitter 13 may be a polarizing filter of a multilayer film structure (barrel DBEF) or a birefringent beam splitting prism. The polarization beam splitter 13 is a structure in which the functions of polarization and the beam splitter are integrated, which can function as a polarizing plate, that is, light rays that are only allowed to vibrate in the same direction as the polarizing plate. Passed. Among them, DBEF is a product manufactured by 3M Company, which has higher cost, lighter weight and higher practicability than birefringent prisms. Of course, other types of structures can be used to accomplish the transmission of light in one vibration direction and the reflection of light in the other vibration direction.

The backlight module provided by the embodiment of the invention uses the above-mentioned light conversion device. In the light conversion device, since the collimating lens is provided, the scattered natural light can be concentrated into a beam of light, and the beam is a line polarized light including two vibration directions perpendicular to each other, and the linearly polarized light obtained by the collimating lens is irradiated to When the beam splitter is polarized, its incident angle is an acute angle. Therefore, after the polarizing beam splitter, the direction of light propagation in one direction of the polarized light is constant, and the transmitted light is transmitted light; the light of another vibration direction is reflected at the polarizing beam splitter, that is, the reflected light passes through At least two reflections of the reflection module, the incident light becomes the same vibration direction as the transmitted light and is emitted. It can be seen from the above process that the natural light passes through the collimating lens, the polarizing beam splitter and the reflecting module, and the light in the two vibration directions can finally be emitted in the same vibration direction, so that the light of different vibration directions can be utilized, thereby avoiding the waste of the light source. , improved light source utilization.

The embodiment of the invention further provides a display device comprising the backlight module described in the above embodiments.

The display device provided by the embodiment of the invention uses the backlight module, and the backlight module uses the above-mentioned light conversion device. In the light conversion device, since the collimating lens is provided, the scattered natural light can be concentrated into a beam of light, and the beam is a line polarized light including two vibration directions perpendicular to each other, and the linearly polarized light obtained by the collimating lens is irradiated to When the beam splitter is polarized, its incident angle is an acute angle. Therefore, after the polarizing beam splitter, the direction of light propagation in one direction of the polarized light is constant, and the transmitted light is transmitted, and the light of another vibration direction is reflected at the polarizing beam, that is, reflected light; At least two reflections of the reflective module cause the reflected light to become the same direction of vibration as the transmitted light and exit. It can be seen from the above process that the natural light passes through the collimating lens, the polarizing beam splitter and the reflecting module, and the light in the two vibration directions can finally be emitted in the same vibration direction, so that the light of different vibration directions can be utilized, thereby avoiding the waste of the light source. , improved light source utilization.

In practical applications, the display device can be a liquid crystal display panel, a liquid crystal television, a liquid crystal display, a mobile phone, a digital photo frame, or a personal handheld computer. Further, in order to obtain linearly polarized light in the prior art, a lower polarizing plate is usually provided on the side of the display adjacent to the light-emitting surface of the light guide plate. In contrast, in this embodiment, linearly polarized light is directly obtained by the light conversion device, and there is no need to provide a lower polarizing plate, which simplifies the process and saves cost.

The above is only the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any change or replacement that can be easily conceived by those skilled in the art within the technical scope of the present invention is All should be covered by the scope of the present invention. Accordingly, the scope of the invention should be determined by the scope of the appended claims.

Claims

claims

1. A light conversion device, including a collimating lens and a reflection module. The collimating lens is used to collimate natural light and simultaneously convert it into linearly polarized light including two mutually perpendicular vibration directions; the collimating lens A polarizing beam splitter is provided on the side of the light exit surface, and the incident angle of the linearly polarized light obtained through the collimating lens to the polarizing beam splitter is an acute angle; the polarizing beam splitter is used to change the vibration direction of the linearly polarized light. The light in the same direction as the transmission axis of the polarizing beam splitter is transmitted, and the light in other vibration directions is reflected; the reflected light and the transmitted light passing through the polarizing beam splitter are emitted in the same vibration direction.

2. The light conversion device according to claim 1, wherein the light exit surface of the collimating lens in the reflection module is in contact with the light entrance surface of the reflection module.

3. The light conversion device according to any one of claims 1-2, wherein the incident angle of the linearly polarized light irradiating the polarizing beam splitter is 45 degrees.

4. The light conversion device according to any one of claims 2-3, wherein the incident angle of the light irradiating the total reflection surface in the reflection module is 45 degrees.

5. The light conversion device according to any one of claims 2 to 4, wherein the total reflection surface includes a first reflection surface, a second reflection surface, a third reflection surface and a fourth reflection surface; After the light reflected by the polarizing beam splitter is reflected by the first reflective surface, the second reflective surface, the third reflective surface and the fourth reflective surface in sequence, the vibration direction and the emission direction are the same as the vibration direction and emission direction of the transmitted light.

6. The light conversion device according to any one of claims 1 to 5, wherein the reflection module is a prism; and the polarizing beam splitter is fixed in the prism.

7. The light conversion device according to claim 6, wherein a resin is fixed between the polarizing beam splitter and the prism, one end of the resin is fixedly connected to the prism, and the other end of the resin is fixedly connected to the polarizing beam splitter. The beam splitter is fixedly connected.

8. The light conversion device according to claim 7, wherein the refractive index of the resin is equal to The refractive indices of the prism materials are similar.

9. The light conversion device according to claim 1, wherein the polarizing beam splitter is a polarizing filter with a multi-layer film structure or a birefringent beam splitting prism.

10. The light conversion device according to claim 1, wherein the collimating lens is a total internal reflection collimating lens.

11. A backlight module, comprising the light conversion device according to any one of claims 1-10.

12. A display device, comprising the backlight module of claim 11.