WO2019038824A1 - Light control member, liquid crystal display device, and method for manufacturing light control member - Google Patents

Abstract

A light diffusion member 9 comprises: a plurality of light shielding parts 40 capable of blocking light and formed on a plate-like optically-transmissive base material 39, the light shielding parts 40 being formed as a frustum that tapers toward the base material 39; an optically-transmissive light diffusion part 41 formed on the base material 39 in a region where no light shielding part 40 is formed; and a plurality of hollow parts 42 formed on the light shielding parts 40 and defined by the side surface of the light diffusion part 41, the hollow parts 42 being formed as a frustum that tapers away from the base material 39.

Description

Light control member, liquid crystal display device, and method of manufacturing light control member

The present invention relates to a light control member, a liquid crystal display device, and a method of manufacturing the light control member.

In some liquid crystal display devices such as liquid crystal televisions, light control members for expanding a viewing angle are used. The light control member is disposed in front of the liquid crystal panel and diffuses light from the liquid crystal panel side to the front. For example, Patent Document 1 discloses a liquid crystal display in which the viewing angle characteristics are improved by such a light control member (light diffusion member).

The light control member has a plurality of light shielding portions and a light diffusion portion filling the space between the light shielding portions. The light diffusion portion is provided to diffuse light from the liquid crystal panel side to the front. The light shielding portion is provided to prevent the light entering the light control member from being transmitted through the light control member without being diffused. Such a configuration extends the viewing angle of the liquid crystal television.

Patent No. 5943265 gazette

However, there are cases where the side surface of the light shielding portion shields even the light that is to be transmitted through the inside of the light diffusion portion. That is, the side surface of the light shielding portion may restrict the spread of the light in the light diffusion portion. In such a case, the luminance within the viewing angle of the liquid crystal display device is reduced. Therefore, the light control member used in the liquid crystal display device disclosed in Patent Document 1 has room for improvement from the viewpoint of the luminance within the viewing angle.

An object of the present invention is to provide a light control member, a liquid crystal display device, and a method of manufacturing the light control member with improved light diffusion performance.

The light control member according to an embodiment of the present invention is
A plurality of light shielding portions formed on a plate-like light transmitting base material, having a light shielding property, and having a frustum shape tapered toward the base material;
A light diffusing portion formed in a region on the substrate where the light shielding portion is not formed, and having light transparency;
And a plurality of hollow portions having a frustum shape which is formed on the light shielding portion, is divided by the side surface of the light diffusion portion, and is tapered in a direction away from the base material.

The liquid crystal display device according to one embodiment of the present invention is
When the surface of the light shielding portion opposite to the base material side is a reference surface, the inclination angle of the side surface of the light shielding portion with respect to the reference surface divides the hollow portion with respect to the reference surface. It is smaller than the inclination angle of the said side.

A method of manufacturing a light control member according to an embodiment of the present invention is
Preparing a plate-like substrate having a first surface and a second surface opposite to the first surface and having light transparency;
Forming a first negative resist film on the first surface of the substrate;
Under the second surface of the substrate, a mask having a plurality of openings is disposed at a predetermined distance from the substrate,
The first negative resist film is exposed by irradiating the first negative resist film with diffused light from the second surface side of the substrate through the opening of the mask.
By developing the first negative resist film, a plurality of light blocking portions having a light blocking property are formed on the first surface of the substrate,
A second negative resist film is formed on the first surface of the substrate between the light shielding portions and on the surface of the light shielding portion opposite to the substrate side,
The second negative resist film is exposed by irradiating the second negative resist film with diffused light from the second surface side of the base material,
By developing the second negative resist film, a light diffusing portion having light transparency is formed in a region where the light shielding portion is not formed in the region on the first surface of the base material, Forming a hollow portion partitioned by the side surface of the light diffusion portion on the light shielding portion.

According to the present invention, the light control member, the liquid crystal display device, and the light control member whose light diffusion performance is improved by tapering the shape of the light shielding portion toward the base material and expanding the path of light traveling in the diffusion portion We can provide a way.

FIG. 1 is a perspective view showing a schematic configuration of a liquid crystal display device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a liquid crystal display device. The perspective view which shows a light control member. The top view which shows a light control member. FIG. 2 is a schematic cross-sectional view showing a light control member. The 1st graph which shows the relation between the inclination angle of a shade part, and a radiation intensity rise rate. The 2nd graph which shows the relation between the inclination angle of a shade part, and a radiation intensity rise rate. The 3rd graph which shows the relation between the inclination angle of a shade part, and a radiation intensity rise rate. The 4th graph which shows the relation between the inclination angle of a shade part, and a radiation intensity rise rate. The 5th graph which shows the relation between the inclination angle of a shade part, and a radiation intensity rise rate. The 6th graph which shows the relation between the inclination angle of a shade part, and a radiation intensity rise rate. The 7th graph which shows the relation between the inclination angle of a shade part, and a radiation intensity rise rate. The 8th graph which shows the relation between the inclination angle of a shade part, and a radiation intensity rise rate. The 9th graph which shows the relation between the inclination angle of a shade part, and a radiation intensity rise rate. The 10th graph which shows the relationship between the inclination angle of a shade part, and a radiation intensity rise rate. The 11th graph which shows the relationship between the inclination angle of a light-shielding part, and a radiation intensity rising rate. The 12th graph which shows the relationship between the inclination angle of a shade part, and a radiation intensity rise rate. The 13th graph which shows the relationship between the inclination angle of a shade part, and a radiation intensity rise rate. The 14th graph which shows the relationship between the inclination angle of a light-shielding part, and a radiation intensity rising rate. The 15th graph which shows the relationship between the inclination angle of a light-shielding part, and a radiation intensity rising rate. The 16th graph which shows the relationship between the inclination angle of a light-shielding part, and a radiation intensity rising rate. The 1st process figure showing the manufacturing method of a light control member. The 2nd process drawing which shows the manufacturing method of a light control member. The 3rd process drawing which shows the manufacturing method of a light control member. The 4th process figure which shows the manufacturing method of a light control member.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a perspective view showing a schematic configuration of the liquid crystal display device of the present embodiment. FIG. 2 is a cross-sectional view of the liquid crystal display device. The liquid crystal display device 1 of the present embodiment includes a liquid crystal panel 2 as shown in FIG. 1 and FIG. The liquid crystal panel 2 includes a liquid crystal cell 5, polarizing plates 3 and 7, and retardation films 4 and 6. The liquid crystal display device 1 according to the present embodiment includes a backlight 8 (illumination device) for supplying light to the liquid crystal panel 2 and a light diffusion member (light control member) 9 for diffusing light emitted from the liquid crystal panel 2. Have.

In FIG. 1, the side on which the light diffusion member 9 is disposed, that is, the upper side of the liquid crystal display device 1 is the viewing side. Further, the side on which the backlight 8 is disposed is the back side. Therefore, in the liquid crystal display device 1 of the present embodiment, the light diffusion member 9, the liquid crystal panel 2, and the backlight 8 are disposed in order from the viewing side to the back side.

In the liquid crystal display device 1 of the present embodiment, light emitted from the backlight 8 is supplied to the liquid crystal panel 2. The light is modulated by the liquid crystal panel 2 and a predetermined image, characters, etc. are displayed on the display surface of the liquid crystal panel 2 by the modulated light. Further, the light emitted from the display surface of the liquid crystal panel 2 is diffused by being transmitted through the light diffusion member 9, that is, the light is diffused and emitted from the light diffusion member 9. Thereby, the wide viewing angle characteristic of the liquid crystal display device 1 is secured.

The liquid crystal panel 2 is, for example, an active matrix transmission type liquid crystal panel, and a switching element is disposed in each pixel on the liquid crystal cell 5, thereby enabling on / off control of a signal for each selected pixel. There is. However, the liquid crystal panel applicable to the present invention is not limited to the transmission type liquid crystal panel of the active matrix system.

As shown in FIG. 2, the liquid crystal cell 5 has a TFT substrate 10, a liquid crystal layer 11, and a color filter substrate 12. The TFT substrate 10 is a substrate on which the switching element is disposed corresponding to each pixel. The color filter substrate 12 is composed of a thin glass substrate and a color resist, is disposed to face the TFT substrate 10, and has a function of creating a color of an image. The liquid crystal layer 11 is sandwiched between the TFT substrate 10 and the color filter substrate 12.

As shown in FIG. 1, the backlight 8 includes light sources 36 disposed on a light source substrate 35 and a light guide plate 37. The light source substrate 35 and the light sources 36 disposed thereon are disposed to face the end face of the light guide plate 37. As the light source 36, for example, a light emitting diode (LED) or a cold cathode tube is used. The backlight 8 of this embodiment is an edge light type backlight using an LED.

The light guide plate 37 is a plate-like member having a function of guiding the light emitted from the light source 36 to the liquid crystal panel 2. As a material of the light guide plate 37, for example, a resin material such as an acrylic resin is used. An emission pattern of light is formed on the surface of the light guide plate 37. By adjusting the density and the like of the pattern of the light guide plate 37, it is possible to make the amount of light emitted from the upper surface of the light guide plate 37 uniform in the plane. Specifically, the light emitted from the light source 36 and entering the inside of the light guide plate 37 from the end face of the light guide plate 37 propagates while totally reflecting inside the light guide plate 37, and the emission pattern from the top surface of the light guide plate 37 It is injected with a substantially uniform intensity. Although not shown, a scattering sheet and a prism sheet are disposed on the upper surface of the light guide plate 37. Further, from the viewpoint of increasing the amount of light led to the liquid crystal panel 2, it is preferable that a reflective sheet (not shown) for reflecting light is disposed on the lower surface of the light guide plate 37. The light emitted from the upper surface of the light guide plate 37 is scattered by the scattering sheet, and then condensed by the prism sheet, and is generally collimated and emitted.

In the present embodiment, the backlight 8 is an edge light type, but may be, for example, a direct light type other than the edge light type. In that case, the light source 36 is disposed on the main surface (surface facing the back surface of the liquid crystal panel 2) of the backlight 8 and the light guide plate 37 is not necessary.

A polarizing plate 3 (see FIG. 2) and a retardation film 4 (see FIG. 2) are provided between the backlight 8 and the liquid crystal cell 5. Similarly, a polarizing plate 7 (see FIG. 2) and a retardation film 6 (see FIG. 2) are provided between the liquid crystal cell 5 and the light diffusion member 9. Since these polarizing plates and retardation films are found in a general liquid crystal display device, detailed description will be omitted.

FIG. 3 is a perspective view of the light diffusion member 9. The light diffusion member 9 includes a base 39, a plurality of light shielding portions 40, and a light diffusion portion 41. The plurality of light shields 40 are formed on the back side of the base 39. The light diffusion portion 41 is formed in a region on the base material 39 where the light shielding portion 40 is not formed.

As shown in FIG. 2, the light diffusion member 9 is on the polarizing plate 7 with the light diffusion portion 41 side as the back side (lower side in FIG. 2) and the base 39 side as the visual recognition side (upper side in FIG. 2). Provided in The light diffusion member 9 is fixed to the polarizing plate 7 via the adhesive layer 43.

The substrate 39 has light transparency, and is made of, for example, a transparent resin. The substrate 39 is a plate-like member made of, for example, polyethylene terephthalate (PET). The thickness of the substrate 39 is, for example, 100 μm. The base material 39 is a base when the materials of the light shielding portion 40 and the light diffusion portion 41 are applied, as shown in the manufacturing process described later with reference to FIGS. 6A to 6D. Therefore, the substrate 39 needs to have heat resistance and mechanical strength in the heat treatment step in the manufacturing process. Therefore, the substrate 39 may be made of glass other than resin, which is provided with heat resistance and mechanical strength.

In the present embodiment, the shape of the light shielding portion 40 in a plan view is circular. The light shields 40 vary in size, and are randomly arranged when viewed from the normal direction of the main surface of the substrate 39. In addition, the light shielding portion 40 has a truncated cone shape which is tapered toward the base 39. The light shielding portion 40 is made of, for example, an organic material having light absorbability (light shielding property) and photosensitivity, such as a black resist and a black ink. In addition, a metal film such as a multilayer film of Cr (chromium) or Cr / Cr oxide may be used.

The light diffusion portion 41 is disposed on the back side of the base 39, has light transparency, and is, for example, a transparent resin member. For example, the light diffusion portion 41 is made of an acrylic resin, and the thickness thereof is about the same as that of the base 39.

Further, the light diffusion member 9 is provided with a plurality of hollow portions 42 stacked on the light shielding portion 40. The hollow portion 42 is partitioned by the side surface of the light diffusion portion 41 (corresponding to the reflection surface 41 c described later). Air is present in the hollow portion 42. The hollow portion 42 has a frusto-conical shape that tapers in a direction away from the substrate 39.

As shown in FIG. 2 together, the light diffusion portion 41 has a light emitting end surface 41 a, a light incident end surface 41 b, and a reflecting surface 41 c. The light emission end surface 41 a is the upper surface in the drawing and a surface in contact with the base material 39. The light incident end surface 41b is a surface facing the light emission end surface 41a. The reflective surface 41 c is a tapered side surface of the light diffusion portion 41 and is a surface that divides the hollow portion 42 as described above. That is, the reflective surface 41 c is an interface between the air of the hollow portion 42 and the organic material of the light diffusion portion 41. Therefore, in the reflecting surface 41c, of the light entering the light diffusing portion 41 from the light incident end face 41b, the light having a predetermined incident angle or more is totally reflected.

The light diffusion portion 41 is a portion of the light diffusion member 9 that transmits light. That is, the light that has entered the light diffusion portion 41 is totally reflected by the reflection surface 41 c of the light diffusion portion 41 and is guided and diffused in a substantially confined state inside the light diffusion portion 41 and is emitted. It injects from the end surface 41a. Here, of the two main surfaces of the light diffusion portion 41, the surface on the viewing side is the light emission end surface 41a. On the other hand, the surface on the back side is the light incident end face 41b.

Further, the height from the light incident end surface 41 b of the light diffusion portion 41 to the light emission end surface 41 a is larger than the layer thickness of the light shielding portion 40. In the case of the present embodiment, the layer thickness of the light shielding portion 40 is such a thickness that light can not be transmitted through the light shielding portion 40 and light shielding performance can be ensured, and is about 150 nm as an example. The height from the light incident end surface 41b of the light diffusion portion 41 to the light emission end surface 41a is, for example, about 20 μm.

The refractive index of the base 39 and the refractive index of the light diffusion portion 41 are substantially the same. Accordingly, it is possible to suppress unnecessary refraction and reflection of light when the light entering the light diffusion portion 41 is incident on the base material 39.

In the case of the present embodiment, air is present in the hollow portion 42. Due to the presence of air in the hollow portion 42, the critical angle when light entering the light diffusion portion 41 is incident on the reflection surface 41c is smallest, and the incident angle range totally reflected by the reflection surface 41c is widest. Become. As a result, light loss can be further suppressed and high luminance can be obtained. The hollow portion 42 may be filled with a low refractive index material other than air.

FIG. 4 is a schematic view of the light diffusion member 9. In FIG. 4, the upper left side is a plan view of the light diffusion member 9. The lower left side is a cross-sectional view taken along the line AA of the plan view of the upper left side. The upper right side is a cross-sectional view taken along the line BB in the plan view of the upper left side.

In the light diffusion member 9 of the present embodiment, as shown in the upper left side of FIG. 4, a plurality of light shielding portions 40 are provided in a dotted manner on one surface of the base material 39.

As shown in the lower left side and the upper right side of FIG. 4, as described above, a portion corresponding to the lower side of the light shielding portion 40 is a hollow portion 42 having a truncated cone shape. The light diffusion member 9 has a plurality of hollow portions 42. At portions other than the plurality of hollow portions 42, light diffusion portions 41 are provided in series.

In addition, although the planar shape of the light shielding part 40 is circular in this embodiment, it may be a shape such as a polygon or a semicircle besides this.

FIG. 5 is a schematic cross-sectional view of the light diffusing member 9 showing the relationship between the light shielding part 40 and the light diffusing part 41. As shown in FIG. Here, although FIG. 5 is a cross-sectional view, hatching is not performed on the area which is a cross-section in order to clarify the illustration. In the present embodiment, the surface of the light shielding portion 40 opposite to the base 39 is used as a reference surface R (that is, the boundary surface between the light shielding portion 40 and the hollow portion 42). The inclination angle θ1 is smaller than the inclination angle θ2 of the reflection surface 41c of the light diffusion portion 41 that divides the hollow portion 42 with respect to the reference surface R. In addition, inclination-angle (theta) 1 of side 40a of the light-shielding part 40 and inclination-angle (theta) 2 of the reflective surface 41c of the light-diffusion part 41 may not always be constant, and may change continuously. Further, the inclination angle θ1 of the side surface 40a of the light shielding portion 40 and the inclination angle θ2 of the reflection surface 41c of the light diffusing portion 41 may be different between the plurality of light shielding portions 40 or the plurality of hollow portions 42.

In FIG. 5, part of light rays emitted from the display surface of the liquid crystal panel 2 is virtually shown as light rays LB1 and LB2. The light beams LB1 and LB2 enter the light diffusion member 9 through the polarizing plate 7 and the adhesive layer 43. In particular, the light beam LB1 that has entered the light diffusion portion 41 passes through the region Ar formed by the tapered shape of the light shielding portion 40, and further transmits through the base material 39 and is emitted. Further, although not illustrated as a light beam, the other light beams entering the light diffusion portion 41 are reflected by the reflection surface 41 c, and then pass through the area Ar formed by the tapered shape of the light shielding portion 40, and further the substrate It may be injected through 39. If the light shielding portion 40 does not have a tapered shape but is cylindrical, the region A1 is not formed, and the light beam LB1 is shielded by the side surface 40a of the light shielding portion 40. In other words, the tapered shape of the light shielding portion 40 extends the path of the light beam emitted from the display surface of the liquid crystal panel 2. The light beam LB2 entering the hollow portion 42 is blocked by the reference surface R of the light blocking portion 40.

In addition, in the liquid crystal display device 1, the luminance changes depending on the angle at which the display surface is viewed. When the angle at which the display surface is viewed is an angle (polar angle) with respect to the normal direction of the display surface, the luminance decreases as the polar angle increases. Here, it is required that the polar angle which is 1/3 of the luminance (front luminance) when the display surface is viewed from the front is 42.5 degrees or more. In other words, the luminance when the polar angle is 42.5 degrees is required to be 1/3 or more of the front luminance. Therefore, it is necessary to secure the luminance at least in the range of 42.5 degrees or less at the polar angle.

In the present embodiment, the above-described inclination angle θ1 is set based on the relationship between the polar angle and the required luminance. Specifically, the inclination angle θ1 is set such that light emitted at an angle φ of 42.5 degrees or less with respect to the normal direction of the display surface is not blocked by the light blocking portion 40. Therefore, the inclination angle θ1 is set to an angle θ1max or less that satisfies the following formula (1). For example, the maximum value θ1max of the inclination angle θ1 under the conditions in the present embodiment is 63.2 degrees.

ｎ１：光拡散部の屈折率
ｎ２：空気の屈折率１．０
φ：定数４２．５度

n1: refractive index of light diffusion part n2: refractive index of air 1.0
φ: constant 42.5 degrees

6A to 6H are analysis results showing the radiation intensity increase rate when the inclination angle θ1 of the light shielding portion 40 is changed. The radiation intensity increase rate is a ratio of the radiation intensity at each inclination angle θ1 to the radiation intensity at an inclination angle θ1 of 90 degrees. 6A to 6H, the horizontal axis represents the inclination angle θ1, and the vertical axis represents the radiation intensity increase rate. Further, in these analyses, the inclination angle θ2 of the light diffusion portion 41 is 80 degrees, the film thickness is 9 μm, and the refractive index of the light diffusion portion 41 is 1.5.

In FIG. 6A, the pitch of the light shielding portions 40 is 30 μm, and the film thickness thereof is 1 μm. In FIG. 6B, the pitch of the light shielding portions 40 is 30 μm, and the film thickness thereof is 3 μm. In FIG. 6C, the pitch of the light shielding portions 40 is 30 μm, and the film thickness thereof is 5 μm. In FIG. 6D, the pitch of the light shielding portions 40 is 30 μm, and the film thickness thereof is 10 μm. In FIG. 6E, the pitch of the light shielding portions 40 is 15 μm, and the film thickness thereof is 1 μm. In FIG. 6F, the pitch of the light shielding portions 40 is 15 μm, and the film thickness thereof is 3 μm. In FIG. 6G, the pitch of the light shielding portions 40 is 15 μm, and the film thickness thereof is 5 μm. In FIG. 6H, the pitch of the light shielding portions 40 is 15 μm, and the film thickness thereof is 10 μm. From these analysis results, it can be seen that a high radiation intensity improvement rate can be obtained when the inclination angle θ1 is 60 degrees or less. Further, it can be understood that a higher radiation intensity improvement rate can be obtained when the inclination angle θ1 is set to 60 degrees or less as the film thickness of the light shielding portion 40 is larger.

7A to 7H are graphs similar to FIGS. 6A to 6H, except that analysis conditions are changed to a film thickness of 20 μm of the light diffusion portion 41. In other words, in FIGS. 7A to 7H, analysis conditions other than the film thickness of the light diffusion portion 41 are the same as those in FIGS. 6A to 6H. That is, in FIG. 7A, the pitch of the light shielding portions 40 is 30 μm, and the film thickness thereof is 1 μm. In FIG. 7B, the pitch of the light shielding portions 40 is 30 μm, and the film thickness thereof is 3 μm. In FIG. 7C, the pitch of the light shielding portions 40 is 30 μm, and the film thickness thereof is 5 μm. In FIG. 7D, the pitch of the light shielding portions 40 is 30 μm, and the film thickness thereof is 10 μm. In FIG. 7E, the pitch of the light shielding portions 40 is 15 μm, and the film thickness thereof is 1 μm. In FIG. 7F, the pitch of the light shielding portions 40 is 15 μm, and the film thickness thereof is 3 μm. In FIG. 7G, the pitch of the light shielding portions 40 is 15 μm, and the film thickness thereof is 5 μm. In FIG. 7H, the pitch of the light shielding portions 40 is 15 μm, and the film thickness thereof is 10 μm. Also by referring to these analysis results, it can be seen that a high radiation intensity improvement rate can be obtained when the inclination angle θ1 is 60 degrees or less. Further, as described above, it can be seen that a higher radiation intensity improvement rate can be obtained when the inclination angle θ1 is set to 60 degrees or less as the film thickness of the light shielding portion 40 is larger.

8A to 8D are perspective views showing the manufacturing process of the light diffusing member 9 in order.

The manufacturing method of the light diffusing member 9 constituting the liquid crystal display device 1 having the above configuration will be mainly described. The method of manufacturing the liquid crystal panel 2 may be a conventional method, and the description thereof will be omitted.

First, as shown in FIG. 8A, a PET substrate 39 is prepared. The thickness of the substrate 39 is, for example, 100 μm. Next, a black negative resist (first negative resist) as a light shielding portion material is applied to the upper surface (first surface) of the base material 39 by spin coating to form a coating film 45. The black negative resist contains, for example, carbon, and the film thickness of the coating film 45 is, for example, 150 nm.

Subsequently, the base material 39 which formed the coating film 45 is mounted on a hot plate, and the coating film 45 is prebaked at predetermined temperature (for example, 90 degreeC). Thereby, the solvent in the coating film (first negative resist film) 45 is volatilized.

Next, the photomask (mask) 47 on which a plurality of opening patterns 46 having a planar shape of, for example, a circular shape is formed is a surface (first surface) opposite to the surface (first surface) on which the coating 45 is formed. Place a predetermined distance away from surface 2). Here, the predetermined distance is determined in accordance with the shape of the light shielding portion 40 or the like.

Next, the coating film 45 is irradiated with the light L1 through the photomask 47 and the base material 39 by using an exposure device (not shown) to perform exposure. The light L1 of the present embodiment is diffused light. The method of making light L1 into diffused light is not particularly limited, and for example, a diffusion plate may be disposed under the photomask 47, and the light may be diffused by the diffusion plate. Alternatively, an exposure apparatus that emits diffused light as a light source may be used without using such a diffusion plate.

After exposure using a photomask 47, the coating film 45 made of a black negative resist is developed using a dedicated developer and dried at a predetermined temperature (for example, 100 ° C.). Thereby, as shown to FIG. 8B, several light-shielding part 40 of a truncated cone shape is formed in one surface of the base material 39. As shown in FIG. As shown in FIG. 8A, since the light L1 is diffused light as described above, it passes through the opening pattern 46 of the photomask 47, is diffused so as to spread outward, and reaches the coating film 45. Therefore, the black negative resist constituting the coating film 45 becomes a light shielding portion 40 having a truncated cone shape which is tapered at a certain angle toward the base material 39. The inclination angle θ1 (see FIG. 5) of the side surface 40a of the light shielding portion 40 can be controlled by adjusting the degree of diffusing the light L1 according to the type of the light L1, the arrangement of the photomask 47, and the like.

As described later, in the present embodiment, the transparent negative resist (second negative resist) is exposed using the light shielding portion 40 as a mask to form the hollow portion 42. Therefore, the position of the opening pattern 46 of the photomask 47 corresponds to the position where the hollow portion 42 is formed. In the present embodiment, the plurality of opening patterns 46 are all circular patterns. The size of the radius of the opening pattern 46 is not uniform and varies. The arrangement of the intervals (pitches) between the adjacent opening patterns 46 is neither regular nor periodic nor random. However, the distance (pitch) of the opening patterns 46 is preferably smaller than the distance (pitch, for example, 150 μm) of the pixels of the liquid crystal panel 2. As a result, at least one light shielding portion 40 is formed in the pixel, so that a wide viewing angle can be achieved.

Next, as shown in FIG. 8C, a transparent negative resist (second negative resist) as a light diffusion portion material is applied and coated on the upper surface of the substrate 39 and the upper surface of the light shielding portion 40 using spin coating. A film (second negative resist film) 48 is formed. The transparent negative resist is made of, for example, an acrylic resin, and the film thickness of the coating film 48 is, for example, 20 μm.

Next, the base material 39 on which the coating film 48 is formed is placed on a hot plate, and the coating film 48 is prebaked at a predetermined temperature (for example, 95 ° C.). Thereby, the solvent in the coating film 48 is volatilized.

Then, the light L 2 is passed through the base material 39 to the coating film 48 using the light shielding part 40 as a mask from the surface (first surface) and the opposite surface (second surface) side of the base material 39 where the light shielding part 40 is formed. Irradiate and expose. The light L2 of the present embodiment is diffused light. The method of making light L2 into diffused light is not particularly limited, and for example, a diffusion plate may be disposed under the substrate 39, and the light may be diffused by the diffusion plate. Alternatively, an exposure apparatus that emits diffused light as a light source may be used without using such a diffusion plate. After exposure with the light L2, the base material 39 on which the coating film 48 is formed is placed on a hot plate, and post-exposure baking (PEB) of the coating film 48 is performed at a predetermined temperature (for example, 95 ° C.).

Next, the coating film 48 made of a transparent negative resist is developed using a dedicated developing solution, and post-baked at a predetermined temperature (for example, 100 ° C.). Thereby, as shown to FIG. 8D, the transparent resin layer (light-diffusion part) 41 which has several hollow parts 42 is formed in one surface (1st surface) of the base material 39. As shown in FIG.

In this embodiment, as shown in FIG. 8C, light L2 is used and exposure is performed using the light shielding portion 40 as a mask, so the transparent negative resist forming the coating film 48 is outside the non-formation region of the light shielding portion 40. It is exposed at a constant angle so as to spread out. In this process, the position of the opening pattern 46 of the photo mask 47 is shielded by the light blocking portion 40 and the other positions are exposed as compared with the process of forming the light blocking portion 40 described above. An exposure pattern inverted from the exposure pattern of That is, since the transparent negative resist is exposed by the light spreading at a certain angle so as to spread outward from the non-formation region of the light shielding portion 40, a truncated cone which tapers in the direction away from the substrate 39 contrary to the light shielding portion 40 A hollow portion 42 of a shape is formed. The inclination angle θ2 (see FIG. 5) of the reflection surface 41 c of the light diffusion portion 41 can be controlled by the degree of diffusion of the light L 2 as in the process of forming the light shielding portion 40.

As described above, through the steps of FIGS. 8A to 8D, the light diffusion member 9 of the present embodiment is completed. In the present embodiment, an example using a liquid resist has been described, but a film-like resist may be used instead of this configuration.

Finally, as illustrated in FIG. 2, the completed light diffusion member 9 has the substrate 39 directed to the viewing side and the light diffusion portion 41 is opposed to the polarizing plate 7, and the liquid crystal is interposed through the adhesive layer 43. Stick on panel 2 The liquid crystal display device 1 of the present embodiment is completed by the above steps.

The effects and advantages derived from the above configuration will be described.

As shown in FIG. 5, according to the present embodiment, the light shielding portion 40 has a shape that is tapered toward the base material 39, so that light traveling inside the light diffusion portion 41 is blocked by hitting the side surface 40 a of the light shielding portion 40. Can be prevented. Specifically, total reflection of light occurs on the side surface 41 c of the light diffusion portion 41 that divides the hollow portion 42 due to the difference in refractive index. By the total reflection of the light, the traveling direction of the light incident on the light diffusion portion 41 is variously changed, and the light is diffused. As in the above-described configuration, the light blocking portion 40 has a tapered shape toward the base material 39, so that the possibility that part of the light to be transmitted hits the side surface 40 a of the light blocking portion 40 can be reduced. In other words, by tapering the light shielding portion 40 toward the base 39, the transmission path of light traveling in the light diffusion portion can be expanded. Therefore, when the light diffusion member 9 is illuminated, the amount of light passing through the light diffusion member 9 can be increased.

Further, according to the present embodiment, since the inclination angle θ1 of the light shielding portion 40 is smaller than the inclination angle θ2 of the light diffusion portion 41, the light is blocked from the traveling path of the light reflected by the reflection surface 41c of the light diffusion portion 41. Since the side surface 40 a of the portion 40 escapes more, the light to be transmitted is less likely to be blocked by the light blocking portion 40.

Further, according to the present embodiment, by defining the inclination angle θ1 of the light shielding portion 40 to 45 degrees or less, it is possible to reduce the amount of light shielding of light to be transmitted originally shielded by the side surface 40 a of the light shielding portion 40. .

Further, according to the present embodiment, since the liquid crystal display device 1 is configured using the light diffusion member 9 in which the transmission amount of light to be transmitted is increased as described above, the viewing angle of the liquid crystal display device 1 It is possible to increase the brightness inside.

Further, according to the present embodiment, it is possible to manufacture the light diffusion member 9 capable of suitably securing the light transmission amount while maintaining the light diffusion property. In particular, in the method of manufacturing the light diffusion member 9 described in the present embodiment, the tapered shape of the light shielding portion 40 is easily formed only by adding the photomask 47 to the existing developing device without adding large-sized equipment. it can. Therefore, existing equipment can be used effectively.

The present invention and embodiments are summarized as follows.

In one embodiment, the light control member according to the present invention
A plurality of light shielding portions formed on a plate-like light transmitting base material, having a light shielding property, and having a frustum shape tapered toward the base material;
A light diffusing portion formed in a region on the substrate where the light shielding portion is not formed, and having light transparency;
And a plurality of hollow portions having a frustum shape which is formed on the light shielding portion, is divided by the side surface of the light diffusion portion, and is tapered in a direction away from the base material.

According to this configuration, it is possible to prevent the light traveling inside the light diffusion portion from being hit against the side surface of the light shielding portion and being shielded because the light shielding portion is tapered toward the base material. Specifically, total reflection of light occurs from the difference in refractive index on the side surface of the light diffusion portion that defines the hollow portion. The total reflection of the light variously changes the traveling direction of the light incident on the light control member and diffuses the light. As in the above-described configuration, the light blocking portion has a shape that is tapered toward the base, so that the possibility that part of light traveling in the light diffusion portion hits the side surface of the light blocking portion can be reduced. In other words, the light shielding portion is tapered toward the base material, thereby expanding the transmission path of light traveling in the light diffusing portion. Therefore, when the light control member is illuminated, the amount of diffused light transmitted through the light control member can be increased.

In one aspect, the light control member
Even if the inclination angle of the side surface of the light shielding portion with respect to the reference surface which is the surface opposite to the base material of the light shielding portion is smaller than the inclination angle of the side surface of the light diffusing portion which divides the hollow portion with respect to the reference surface. Good.

According to this configuration, the side surface of the light blocking portion largely escapes from the traveling path of the light reflected by the reflection surface of the light diffusing member, and thus the light to be transmitted is difficult to be blocked by the light blocking portion.

In one aspect, in the light control member, the inclination angle of the side surface of the light shielding unit with respect to the reference surface may be equal to or less than a value θ1max satisfying the following expression.

ｎ１：光拡散部の屈折率
ｎ２：空気の屈折率１．０
φ：定数４２．５度

n1: refractive index of light diffusion part n2: refractive index of air 1.0
φ: constant 42.5 degrees

According to this configuration, since the inclination angle of the light blocking portion is defined to be equal to or less than the predetermined value θ1max, the amount of light blocked by the side surface of the light blocking portion can be reduced. The predetermined value θ1max here will be described later.

In one embodiment, the liquid crystal display device according to the present invention is
A lighting device,
A liquid crystal panel that modulates light emitted from the lighting device and displays an image on a display surface;
And a light control member as described above for diffusing the light emitted from the display surface.

According to this configuration, since the transmission amount of the diffused light in the light control member is increased as described above, the luminance in the viewing angle of the liquid crystal display device can be increased. In particular, by using a light control member in which the inclination angle of the light shielding portion is equal to or less than the predetermined value θ1max, the amount of light blocked by the side surface of the light shielding portion can be reduced, and appropriate brightness required for the liquid crystal display device is ensured. Is possible. In the liquid crystal display device, the luminance changes depending on the angle at which the display surface is viewed. When the angle at which the display surface is viewed is an angle (polar angle) with respect to the normal direction of the display surface, the luminance decreases as the polar angle increases. Here, it is required that the polar angle which is 1/3 of the luminance (front luminance) when the display surface is viewed from the front is 42.5 degrees or more. In other words, the luminance when the polar angle is 42.5 degrees is required to be 1/3 or more of the front luminance. Therefore, it is necessary to secure the luminance at least in the range of 42.5 degrees or less at the polar angle. In the above configuration, the above-described inclination angle θ1 is set based on the relationship between the polar angle and the required luminance. Specifically, the inclination angle θ1 is set so that light emitted at an angle φ of 42.5 degrees or less with respect to the normal direction of the display surface is not blocked by the light blocking portion.

In one embodiment, a method of manufacturing a light control member according to the present invention is
Preparing a plate-like light transmitting substrate having a first surface and a second surface facing each other;
Applying a black negative resist to the first side of the substrate;
A mask having a plurality of openings is disposed on the second surface side of the substrate at a predetermined distance from the substrate,
By irradiating diffused light toward the black negative resist through the mask, the black negative resist is exposed by the light passing through the opening of the mask and the substrate.
After the exposure of the black negative resist, the black negative resist is developed using a predetermined developing solution to form a plurality of frustum-shaped light shielding portions tapered toward the substrate.
Applying a transparent negative resist to the first surface of the substrate including the light shielding portion;
By irradiating diffused light from the first surface side of the base toward the transparent negative resist, the transparent negative resist is exposed by light passing through the base while being partially blocked by the light shielding portion. ,
A light diffusion portion is formed by developing the transparent negative resist using a predetermined developer after the exposure of the transparent negative resist.
After the development of the transparent negative resist, heating is performed at a predetermined temperature to form a plurality of hollow portions, which are spaces formed by volatilization of the transparent negative resist that is not exposed because it is shielded by the light shielding portion. including.

According to this method, as described above, it is possible to manufacture the light control member capable of suitably securing the light transmission amount while maintaining the light diffusibility. In particular, according to this method, the tapered shape of the light shielding portion can be easily formed only by adding the mask to the existing developing device without adding a large-sized facility. Therefore, existing equipment can be used effectively.

DESCRIPTION OF SYMBOLS 1 liquid crystal display device 2 liquid crystal panel 3 polarizing plate 4 retardation film 5 liquid crystal cell 6 retardation film 7 polarizing plate 8 back light 9 light diffusion member (light control member)
DESCRIPTION OF SYMBOLS 10 TFT substrate 11 liquid crystal layer 12 color filter substrate 35 light source substrate 36 light source plate 37 light guide plate 39 substrate 39 a side surface 40 light shielding portion 40 a side 41 light diffusion portion 41 a light emitting end surface 41 b light incident end surface 41 c reflective surface 42 hollow portion 43 adhesive layer 45 Coating film (first negative resist film)
46 Opening pattern 47 Photo mask (mask)
48 Coating film (second negative resist film)

Claims (5)

A plurality of light shielding portions formed on a plate-like light transmitting base material, having a light shielding property, and having a frustum shape tapered toward the base material;
A light diffusing portion formed in a region on the substrate where the light shielding portion is not formed, and having light transparency;
A light control member comprising: a plurality of hollow portions formed on the light shielding portion, partitioned by side surfaces of the light diffusion portion, and having a frustum shape tapered in a direction away from the base. When the surface of the light shielding portion opposite to the base material side is a reference surface, the inclination angle of the side surface of the light shielding portion with respect to the reference surface divides the hollow portion with respect to the reference surface. The light control member according to claim 1, which is smaller than the inclination angle of the side surface. The light control member according to claim 2, wherein an inclination angle of the side surface of the light shielding portion with respect to the reference surface is equal to or smaller than θ1max obtained by the following equation.

n1: refractive index of light diffusion part n2: refractive index of air 1.0
φ: constant 42.5 degrees A lighting device,
A liquid crystal panel that modulates light emitted from the lighting device and displays an image on a display surface;
The light control member according to any one of claims 1 to 3, which diffuses the light emitted from the display surface. Preparing a plate-like substrate having a first surface and a second surface opposite to the first surface and having light transparency;
Forming a first negative resist film on the first surface of the substrate;
Under the second surface of the substrate, a mask having a plurality of openings is disposed at a predetermined distance from the substrate,
The first negative resist film is exposed by irradiating the first negative resist film with diffused light from the second surface side of the substrate through the opening of the mask.
By developing the first negative resist film, a plurality of light blocking portions having a light blocking property are formed on the first surface of the substrate,
A second negative resist film is formed on the first surface of the substrate between the light shielding portions and on the surface of the light shielding portion opposite to the substrate side,
The second negative resist film is exposed by irradiating the second negative resist film with diffused light from the second surface side of the base material,
By developing the second negative resist film, a light diffusing portion having light transparency is formed in a region where the light shielding portion is not formed in the region on the first surface of the base material, A method of manufacturing a light control member, comprising: forming a hollow portion partitioned by the side surface of the light diffusion portion on the light shielding portion.

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