WO2008023484A1

WO2008023484A1 - Liquid crystal display

Info

Publication number: WO2008023484A1
Application number: PCT/JP2007/060767
Authority: WO
Inventors: Akihiro Yamamoto; Iori Aoyama; Masumi Kubo
Original assignee: Sharp Kabushiki Kaisha
Priority date: 2006-08-24
Filing date: 2007-05-28
Publication date: 2008-02-28

Abstract

A liquid crystal display comprises a liquid crystal panel (1), a backlight (3) for emitting light passing from the rear surface to the front surface of the liquid crystal panel (1), a lenticular lens (4) installed on the front surface side of the liquid crystal panel (1) and formed by arranging aspherical lenses (4a) parallel on the same plane for condensing the light from the liquid crystal panel (1) and guiding it to the outside, and a light shielding layer (5) installed on the front surface of the lenticular lens (4) and having openings (5a) formed in the aspherical lenses (4a) along their respective optical axes. Consequently, the liquid crystal display in which the display characteristics vary with the viewing direction can be provided.

Description

Specification

Liquid crystal display

Technical field

[0001] The present invention relates to a liquid crystal display device including a liquid crystal panel and a backlight unit.

Background art

In recent years, liquid crystal display devices have adopted a method in which a light source is disposed on the back side of a liquid crystal panel and the liquid crystal panel is irradiated with light from the light source, a so-called knock light method. . Such backlight type systems are roughly classified into an edge light type and a direct type. In the edge light system, a light source lamp such as a cold cathode fluorescent tube (CCFT) is mounted along the side edge of a flat light guide plate made of acrylic resin with excellent light transmission, and the light source lamp The light from is subjected to multiple reflection within the light guide plate. On the other hand, the light guide plate is not used in the direct type. Recently, the edge light type backlight system has become mainstream because it is easy to reduce the thickness.

For example, a configuration shown in FIG. 13 is generally known as a liquid crystal display device equipped with an edge light type backlight system. In this configuration, a liquid crystal panel 103 sandwiched between polarizing plates 101 and 102 is provided, and a light guide plate 110 made of a substantially rectangular plate-like PMMA (polymethylmetatalylate) or the like is disposed on the lower surface side thereof. In addition, a diffusion film (diffusion layer) 121 is provided on the upper surface (light output surface) of the light guide plate 110.

[0004] Further, on the lower surface of the light guide plate 110, there is a scattering / reflecting pattern portion 111 for efficiently scattering and reflecting the light introduced into the light guide plate 110 so as to be uniform in the direction of the liquid crystal panel 103. It is provided by printing or other means!

In addition, a light source lamp 113 is attached to the light guide plate 110 along the side end portion. Further, the light source lamp 113 that allows light from the light source lamp 113 to enter the light guide plate 110 efficiently. A high-reflectance lamp reflector 114 is provided so as to cover the back side of the lamp.

[0006] The scattering reflection pattern 111 is made of white titanium dioxide (TiO 2) powder that is transparent. A mixture mixed with a solution such as an adhesive is formed by, for example, printing a dot pattern on the lower surface of the light guide plate 110 and drying it. In other words, as one means for increasing the brightness, the scattering reflection pattern portion 111 imparts directivity to the light incident on the light guide plate 110 and guides the light toward the light exit surface side. .

[0007] By the way, in such a liquid crystal display device, there is a strong demand as a market need to be thin, low power consumption, and high luminance. Along with this, the knock light system mounted on the liquid crystal display device is also required to be thin, low power consumption and high brightness.

[0008] In particular, the recent awakening! / In the development of color liquid crystal display devices! / The light transmittance of liquid crystal panels is much lower than that of monochrome-compatible liquid crystal panels. Improving brightness is an essential issue in order to obtain low power consumption of the device itself.

Therefore, for example, in the liquid crystal display device disclosed in Patent Document 1, as shown in FIG. 14, a liquid crystal panel 203 and a backlight system 210 for irradiating the liquid crystal panel 203 with light from the back side are provided. A light-blocking portion 230 provided on the front side of the backlight system 210 and having a lens layer 220 force S for guiding the light from the light source 213 to the liquid crystal node 203 and having an opening near the focal plane of the lens layer 220. Have! /

[0010] With this, the directivity of the knocklight can be increased by reducing the size of the opening of the light shielding portion 230.

Patent Document 1: Japanese Patent Publication “JP 2005-43907 (Publication Date: February 17, 2005)”

Patent Document 2: Japanese Patent Publication “Japanese Patent Laid-Open No. 2001-113538 (Publication Date: April 24, 2001)”

Disclosure of the invention

However, even in the above conventional liquid crystal display device, as shown in FIG. 15, if light obliquely incident on the liquid crystal panel 303 is present, a difference in display characteristics occurs due to a difference in observation direction. Has a problem!

More specifically, as shown in FIG. 16, there is light incident obliquely on the liquid crystal panel 303. Then, the normalized luminance is larger in the region where the viewing angle Θ is large than in the region where the viewing angle Θ is small. Here, the above-mentioned area means a spatial range where a viewpoint for viewing the display on the liquid crystal panel 303 exists. As a result, the contrast is high when viewed from the front direction, whereas the display appears whitish when viewed from the oblique direction (referred to as floating white) and the contrast is lowered. That is, the viewing angle characteristic is poor.

[0013] This problem is caused by light vertically incident on the liquid crystal panel 303 from the backlight (referred to as vertical light), light obliquely incident on the liquid crystal panel 303 (referred to as oblique light), force S, and passing through the liquid crystal layer. This is because, in particular, in black display and low gradation display, the incident angle to the liquid crystal molecules is different between vertical light and oblique light. That is, the phase difference given by the liquid crystal layer is different between vertical light and oblique light, and the amount of leakage light from the polarizing plate is different, resulting in the above problem. Since the light is blocked not by the liquid crystal but by the polarizing plate, if the phase difference is different between the vertical light and the oblique light, the amount of leakage from the polarizing plate is different.

In FIG. 16, the normalized luminance is a luminance corresponding to each gradation based on the maximum luminance. Each line shows the normalized luminance plotted every 32 gradations. For example, in the case of gradation 255, the luminance corresponding to gradation 255 / luminance corresponding to gradation 255 = 100. On the other hand, in the figure, for example, a black circle (譬) indicates a normalized luminance corresponding to the gradation 159, and a luminance corresponding to the gradation 159 / a luminance corresponding to the gradation 255.

In recent years, the polarizing plate 301 disposed on the front side of the liquid crystal panel 303 is often subjected to anti-reflection (AG: Anti Glare) treatment, so that it enters the liquid crystal panel 303 vertically. Since both light and obliquely incident light are diffused on the surface of the polarizing plate 301, the contrast in the front direction is reduced.

The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a liquid crystal display device capable of preventing a difference in display characteristics due to a difference in observation direction. Nimes · ο.

In order to solve the above problems, a liquid crystal display device of the present invention includes a liquid crystal panel, a backlight unit that irradiates light from the back side to the front side of the liquid crystal panel, and the liquid crystal A plurality of first lenses that are provided on the front side of the panel and have a function of condensing and diffusing part of the light from the liquid crystal panel to the outside are arranged in parallel on the same plane. And a light-shielding layer provided on the front side of the first lens layer and having an opening on each optical axis of the first lens.

[0018] According to the above invention, on the front side of the liquid crystal panel, the first lens layer in which a plurality of first lenses are arranged side by side on the same plane is provided, and the first lens layer On the front side, a light shielding layer having an opening on each optical axis of the first lens is provided.

For this reason, the light emitted from the backlight unit passes through the liquid crystal panel, is condensed by the first lens layer, and is emitted to the outside. At this time, since the opening of the light shielding layer is provided on each optical axis of the first lens, the light passing through the opening of the light shielding layer is derived from light substantially perpendicular to the liquid crystal panel.

On the other hand, of the light emitted from the backlight unit, the light incident obliquely on the liquid crystal panel is the liquid crystal panel force. The force emitted obliquely as leakage light. This obliquely emitted light hits the light shielding layer and blocks light. It does not come out on the front side of the layer, or comes out on the front side of the light shielding layer.

[0021] As a result, when the liquid crystal panel is viewed from an oblique direction, the existing leaked light is eliminated or extremely reduced, so that the display looks whitish when viewed from an oblique direction as in the prior art. The problem of low contrast is solved. Further, the contrast when viewed from the front direction and the contrast when viewed from the oblique direction are made uniform.

Accordingly, it is possible to provide a liquid crystal display device that can prevent a difference in display characteristics due to a difference in observation direction.

It should be noted that the light-shielding layer can prevent external light from entering the liquid crystal panel also in the present invention, and prevents a decrease in contrast in a bright place due to light reflected from, for example, pixel electrodes of the liquid crystal panel. can do. For example, the liquid crystal projection television disclosed in Patent Document 2 is common in that a lenticular lens is provided with a striped light shielding layer. However, the light shielding layer of the present invention is different from the light shielding layer disclosed in Patent Document 2 in that the main purpose is to shield light emitted obliquely from the liquid crystal panel.

In the liquid crystal display device of the present invention, it is preferable that the light shielding layer has a light absorption property. Yes.

That is, as described above, among the light emitted from the knocklight unit, the light incident obliquely on the liquid crystal panel is the liquid crystal panel force that is emitted obliquely as leakage light, and is emitted obliquely. The light hits the light shielding layer and hardly appears on the front side of the light shielding layer. At this time, the light striking the light shielding layer is originally leaked light, so it is preferable to eliminate it.

In this regard, in the present invention, since the light shielding layer has light absorptivity, the light hitting the light shielding layer is absorbed in the light shielding layer as it is without being reflected. Therefore, the force S is used to extinguish the light hitting the light shielding layer.

In the liquid crystal display device of the present invention, it is preferable that a diffusion layer for diffusing light is provided on the front side of the light shielding layer.

That is, the light that has passed through the opening of the light shielding layer is light that has passed through the first lens layer.

There is little light of components other than the direction diffused by the lens layer. Therefore, there is a possibility that the display is insufficient when viewed from a direction other than the direction diffused by the lens layer.

In this respect, in the present invention, since a diffusion layer for diffusing light is provided on the front side of the light shielding layer, the light that has passed through the opening of the light shielding layer is diffused by the diffusion layer and is thus converted into the lens layer. It spreads in directions other than the diffused direction. Therefore, the display does not become insufficient when viewed from any direction.

[0030] In addition, when viewed from any direction, the light passing vertically through the liquid crystal panel is based on the original! /, So the contrast is high! /, And the display is! / .

In the liquid crystal display device of the present invention, it is preferable that the first lens layer has a striped convex surface, and each of the first lenses is an aspheric lens having the convex surface. Yes.

[0032] Thereby, for example, the light in the left-right direction of the display surface can be narrowed, so that no difference occurs in display characteristics due to a difference in observation direction in the left-right direction.

In the liquid crystal display device of the present invention, it is preferable that the opening of the light shielding layer is formed in a stripe shape along the convex surface of the aspheric lens.

[0034] Thereby, for example, in the left-right direction, out of the light emitted from the backlight unit The light incident obliquely on the liquid crystal panel is emitted as leaked light obliquely from the liquid crystal panel.

1S This obliquely emitted light hits the light shielding layer and does not come out to the front side of the light shielding layer. Therefore, there is no difference in display characteristics due to differences in observation direction in the left-right direction.

[0035] Further, in the liquid crystal display device of the present invention, a plurality of second lenses that guide light from the backlight unit to the liquid crystal panel are arranged in parallel between the liquid crystal panel and the backlight unit. It ’s preferable to have 2 lens layers!

Thereby, the light emitted from the backlight unit is collected by the second lens layer and then incident on the liquid crystal panel. Accordingly, less of the light emitted from the backlight unit is incident obliquely on the liquid crystal panel. As a result, it is possible to reduce light emitted from the liquid crystal panel obliquely as leakage light.

In the liquid crystal display device of the present invention, a plurality of second lenses that guide light from the backlight unit to the liquid crystal panel are provided on the same plane between the liquid crystal panel and the backlight unit. And a second lens layer arranged side by side,

The first lens layer and the second lens layer each have a stripe-like convex surface, and the first lens and the second lens are each composed of an aspheric lens having the convex surface, It is preferable that the stripe-shaped convex ridge line in the first lens layer and the stripe-shaped convex ridge line in the second lens layer are perpendicular to each other! /.

[0038] Thereby, the light from the backlight unit is condensed in the second lens layer, for example, in the direction orthogonal to the horizontal direction of the liquid crystal panel, while the liquid crystal is condensed in the first lens layer. Light emitted from the liquid crystal panel can be condensed in the left-right direction of the panel.

In the liquid crystal display device of the present invention, it is preferable that each of the first lenses is a microlens, and the opening of the light shielding layer is formed in a circular shape that matches the shape of the microlens. .

[0040] Thereby, in all the oblique directions not only in the left-right direction, there is no difference in display characteristics due to the difference in observation direction.

[0041] In the liquid crystal display device of the present invention, it is preferable that the backlight unit includes a light source arranged immediately below the liquid crystal panel. Thus, in a liquid crystal display device having a backlight unit having a direct light source, it is possible to prevent a difference in display characteristics due to a difference in observation direction.

[0043] In the liquid crystal display device of the present invention, it is preferable that an operation mode of the liquid crystal panel is a vertical alignment mode.

[0044] As a result, the liquid crystal of the vertical alignment mode is better than the TN mode or the horizontal alignment mode.

It has been confirmed by power experiments that it is possible to prevent differences in display characteristics due to differences in observation direction and to improve contrast.

In the liquid crystal display device of the present invention, it is preferable that each of the second lenses is a microlens. This makes it possible to use a microlens as the second lens layer.

[0046] Other objects, features, and advantages of the present invention will be fully understood from the following description. The advantages of the present invention will become apparent from the following description with reference to the accompanying drawings.

Brief Description of Drawings

FIG. 1 is a cross-sectional view showing an embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a cross-sectional view of the main part showing the configuration of the back side of the liquid crystal panel in the liquid crystal display device.

FIG. 3 is a sectional view showing a configuration of a lenticular lens and a light shielding layer in the liquid crystal display device.

FIG. 4 is a plan view showing a configuration of a microlens array as a first lens layer and a light shielding layer in the liquid crystal display device.

FIG. 5 is a cross-sectional view showing the principle of viewing angle improvement by a lenticular lens and a light shielding layer in the liquid crystal display device.

FIG. 6 is a graph showing luminance (gamma) viewing angle characteristics in the horizontal direction in the liquid crystal display device.

FIG. 7 is a graph showing the relationship between the luminance corresponding to the front gradation and the luminance corresponding to the oblique gradation at a viewing angle of 45 degrees in the left-right direction in the liquid crystal display device.

FIG. 8 shows the viewing angle characteristics of black luminance in the horizontal direction in the liquid crystal display device. It is a graph.

9] This is a graph showing the chromaticity change characteristic in the left-right direction in the liquid crystal display device.

10] This figure shows the relationship between the maximum incident angle of light incident on the liquid crystal panel from the backlight and the front contrast (CR). Table (a) shows the case of using liquid crystal in the vertical alignment (VA) mode. Table (b) shows the above relationship when using FFS mode liquid crystal, and graph (c) plots the data in Tables (a) and (b)! /, The

11] It is a diagram showing the relationship between each light concentration of the backlight and the light utilization efficiency of the liquid crystal panel. Graph (b) shows the definition of the light concentration of the backlight, and graph (c) shows the table (a ) Shows the relationship between the concentration of the backlight and the light utilization efficiency of the liquid crystal panel.

12] An exploded perspective view showing a configuration of the liquid crystal display device according to a modification of the liquid crystal display device of the present invention.

FIG. 13 is a cross-sectional view showing a configuration of a conventional general liquid crystal display device.

14] A cross-sectional view showing the configuration of another conventional liquid crystal display device.

15] A sectional view showing the principle of viewing angle characteristics in a conventional liquid crystal display device. 16] Luminance (gamma) characteristics with respect to the viewing angle in the horizontal direction in a conventional liquid crystal display device 17] Model showing a known measurement method for obtaining data indicating the relationship between the maximum backlight incident angle and front contrast (CR) FIG.

Explanation of symbols

1 Hakuho Panenore

2 Light collecting sheet (second lens layer)

3 Knocklight (backlight unit)

4 Lenticular lens (first lens layer)

4a Aspherical lens (first lens)

5 Shading layer

5a opening

5a 'opening 5b Shading part

6 Diffusion layer

10 Liquid crystal display

11 LCD Senor

12 Polarizing plate on LCD panel

13 LCD panel bottom polarizing plate

21 Lenticular lens

22 Reflector

22a opening

31 Reflective sheet

32 light source (direct light source)

33 Diffusion sheet

40 microlens array (first! · Nons layer)

40a micro lens

Θ Viewing angle

BEST MODE FOR CARRYING OUT THE INVENTION

[0049] One embodiment of the present invention is described below with reference to Figs.

[0050] The configuration of the liquid crystal display device 10 of the present embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a schematic configuration of the liquid crystal display device 10.

[0051] As shown in FIG. 1, the liquid crystal display device 10 of the present embodiment includes a liquid crystal panel 1 for displaying an image, and on the back side of the liquid crystal panel 1, the back side of the liquid crystal panel 1 is provided. A backlight 3 as a backlight unit for irradiating light from the front side to the front side, and a condensing sheet 2 as a second lens layer provided between the liquid crystal panel 1 and the backlight 3. . The light collecting sheet 2 is not always necessary in the present invention.

On the other hand, at least a lenticular lens 4 as a first lens layer in which a plurality of lenses are arranged in parallel to guide light from the liquid crystal panel 1 to the outside is provided on the front side of the liquid crystal panel 1. Yes. Further, on the front side of the lenticular lens 4, a light shielding layer 5 having an opening 5 a on each optical axis of the lens is provided, and light is diffused on the front side of the light shielding layer 5. A diffusion layer 6 is provided.

[0054] The lenticular lens 4 and the light-shielding layer 5 guide light vertically incident on the liquid crystal panel 1 (vertical light) to the outside of the liquid crystal display device 10, while light obliquely incident on the liquid crystal panel 1 (oblique light). It plays a role of selecting light transmission and blocking so as not to leave the liquid crystal display device 10 outside!

The liquid crystal panel 1 is a transmissive type, and the backlight 3 is used as a light source. The liquid crystal panel 1 includes a liquid crystal cell 11 having a liquid crystal sandwiched between a pair of translucent substrates, and a liquid crystal panel upper polarizing plate 12 and a liquid crystal panel lower polarizing plate 13 provided on the front and back of the liquid crystal senor 11. ing. In order to avoid interference between the lenticular lens 4 and the pattern of the liquid crystal panel 1, the surface of the polarizing plate 12 on the liquid crystal panel is subjected to diffusion treatment such as AG (Anti Glare) treatment to the extent that the condensing degree is not greatly disturbed. It is also possible to apply.

Note that the liquid crystal mode and the cell structure of the liquid crystal cell 11 of the liquid crystal panel 1 are arbitrary. The driving mode of the liquid crystal panel 1 is also arbitrary. That is, as the liquid crystal panel 1, any liquid crystal panel that can display characters, images, or moving images can be used. Further, the liquid crystal panel 1 may be a panel capable of color display or a panel dedicated to monochrome display. Therefore, in FIG. 1, the detailed structure of the liquid crystal panel 1 is not shown, and the description thereof is also omitted.

As shown in FIG. 2, the backlight 3 includes a reflection sheet 31, a light source 32, and a diffusion sheet 33 in order from the bottom. In the present embodiment, the backlight 3 employs a direct-type backlight system in which a light source 32 is disposed directly below the liquid crystal panel 1, and the light source 32 includes a cold cathode tube (CCFT) or a cold cathode fluorescent tube (CCFT). Uses LED (Light Emitting Diode). In addition, the present invention is not necessarily limited thereto, and for example, an edge light type backlight system in which the light source 32 is provided on the end surface of the backlight 3 may be used.

On the other hand, the light collecting sheet 2 includes a bowl-shaped lenticular lens 21 and a reflector 22 provided on the backlight 3 side, as shown in FIG. The reflector 22 is provided with an opening 22a on each optical axis of a plurality of lenses provided in the lenticular lens 21. ing. As a result, the light emitted from the light source 32 of the backlight 3 passes through the diffusion sheet 33, passes through the opening 22a of the reflector 22, and by the respective lenses of the lenticular lens 21, the liquid crystal panel is substantially perpendicular to the backlight 3. 1 is irradiated.

[0059] The reflected light reflected by the reflector 22 is reflected by the reflector sheet 31, and again passes through the diffuser sheet 33, through the opening 22a of the reflector 22, and the lens (second second lens). The liquid crystal panel 1 is irradiated substantially perpendicularly to the backlight 3 by the lens. Therefore, the amount of vertical light emitted from the lenticular lens 21 to the liquid crystal panel 1 increases.

As described above, the condensing sheet 2 plays a role of improving the display brightness by increasing the vertical light that the lenticular lens 4 and the light shielding layer 5 guide to the outside of the liquid crystal display device 10.

[0061] Note that, as the area of the opening 22a of the reflection sheet 31 is reduced, the directivity of the backlight 3 can be increased. Further, a microlens can be used as the light collecting sheet 2. In this case, the opening of the reflector 22 is formed in a circular shape that matches the shape of the microlens.

Next, the lenticular lens 4 provided on the front side of the liquid crystal panel 1 will be described.

[0063] As shown in Fig. 1, the lenticular lens 4 is formed of a bowl-shaped lens with the flat surface facing the front side. The lenticular lens 4 has a striped convex surface as shown in FIG. In other words, the lenticular lens 4 has a force obtained by arranging a plurality of aspherical lenses 4a (first lenses) having one of the convex surfaces. Each aspherical lens 4a has a maximum height of, for example, 110, a minimum height of, for example, 75 m, and the width of one convex surface, for example, lOO ^ m (98 111 in FIG. 3). Yes. The refractive index is 1.5, for example.

Further, a light shielding layer 5 is provided on the front side of the lenticular lens 4. The light shielding layer 5 allows only light passing through the opening 5a to pass through and blocks other light. The opening 5a of the light shielding layer 5 is provided on the optical axis of the aspherical lens 4a, and the force and the focal point of the aspherical lens 4a are located substantially at the center of the opening 5a. Therefore, the opening 5a is formed in a stripe shape like the convex surface of the aspherical lens 4a. Yes. For example, the width of the opening 5a is 30 m (29 m in FIG. 3), and the width of the light-shielding portion 5b is 70 mm (69 μm in FIG. 3), for example!

In the present embodiment, the first lens layer has a force S that is a lenticular lens 4 in which a plurality of aspherical lenses 4a having one of the convex surfaces are arranged, but is not limited thereto. For example, as shown in FIG. 4, a microlens array 40 in which a plurality of spherical microlenses 40a are arranged can be formed. As a result, the viewing angle characteristics can be improved in the direction orthogonal to the left-right direction as well as the left-right direction with respect to the display surface. Further, at this time, also in the light shielding layer 5, the opening 5a is inevitably replaced with a circular opening 5a ′ matching the shape of the microlens 40a.

Next, as shown in FIG. 1, a diffusion layer 6 is provided on the front side of the light shielding layer 5.

The diffusion layer 6 diffuses the light that has passed through the opening 5a of the light shielding layer 5 radially. Therefore, the viewing angle is widened.

[0067] The effects of the liquid crystal display device 10 having the above configuration will be described with reference to FIG.

As shown in FIG. 5, the light that is vertically incident on the liquid crystal panel 1 and is emitted vertically from the liquid crystal panel 1 passes through the opening 5 a of the light shielding layer 5 through the lenticular lens 4. At this time, the light on the optical axis travels on the optical axis as it is, and the light incident on the end of the aspherical lens 4a is refracted and passes through the opening 5a. That is, since the focal line of the aspherical lens 4a having a condensing function exists in the approximate center of the opening 5a, only light emitted substantially vertically from the liquid crystal panel 1 can pass through the opening 5a of the light shielding layer 5. When the aspherical lens 4a is replaced with the microlens 4Oa, it is positioned approximately at the center of the focal force opening 5a ′ of the microlens 40a.

On the other hand, light incident on the liquid crystal panel 1 obliquely and emitted obliquely from the liquid crystal panel 1 is shielded by the light shielding portion 5b of the light shielding layer 5 when passing through the lenticular lens 4. As a result, the light incident on the liquid crystal panel 1 obliquely and emitted obliquely from the liquid crystal panel 1 is not emitted to the front side of the light shielding layer 5.

[0070] Note that the aperture ratio of the opening 5a, that is, the width of the opening 5a / (the width of the opening 5a + the width of the light shielding portion 5b) is a small force. Display change The force S is reduced, that is, the viewing angle characteristics are improved. Conversely, a larger aperture ratio can improve the display brightness. Therefore, the aperture ratio, lens shape, lens refractive index, etc. should be designed to optimize viewing angle characteristics and brightness.

As a result, as shown in FIG. 6, the viewing angle characteristics of the liquid crystal display device 10 are remarkably improved as compared with FIG. 16 at any gradation, and the normalized luminance is −80 °. ≤View angle Θ≤80 ° shows almost horizontal characteristics. In FIG. 6, the normalized luminance is the luminance corresponding to each gradation based on the maximum luminance. Also, each line shows the normalized brightness plotted every 32 gradations!

Here, FIG. 7 shows the relationship between the front gradation and the oblique gradation at, for example, a viewing angle Θ = 45 °. The front gradation is the gradation that the observer perceives when viewing the display surface of the liquid crystal display device 10 from the front, that is, from a viewing angle of 0 °, and is the gradation that the liquid crystal display device 10 is trying to display. equal. On the other hand, the oblique gradation is a gradation that is perceived when an observer views the display surface of the liquid crystal display device 10 with a viewing angle greater than 0 ° and less than 90 °.

[0073] From the results shown in Fig. 7, in the conventional case, the luminance of the oblique gradation is larger than the luminance of the oblique gradation and the luminance of the front gradation. It can be seen that the ratio of the tone brightness to the front tone brightness is 1: 1. This indicates that so-called whitening is prevented.

[0074] In addition, when viewing the viewing angle characteristics of black luminance, as shown in Fig. 8, in the past, when the black angle was -70 ° ≤ viewing angle Θ ≤ -20 ° and 20 ° ≤ viewing angle Θ ≤ 70 °, Luminance is 0.7 ~; 1. Ocd / m ² , 20 ° ≤ viewing angle Θ ≤ 20 °, which is higher than black luminance of about 0.6 cd / m ² , In this configuration, the black brightness is almost constant at 0.4 cd / m ² at all viewing angles Θ! /.

As for the chromaticity change characteristics, as shown in FIG. 9, in the past, the chromaticity change of each color at the viewing angle Θ = 45 °, the color difference Δ uι v ′ in the u ′ v chromaticity coordinates In contrast, there are some with a large color difference, but in this configuration, the color difference Δ ιι 'ν' is a small value, such as 0.01 or less.

[0076] Fig. 9 shows the chromaticity change characteristics in the Macbeth chart. From the first dark skin to the 18th cyan from the left is a chromatic color, and the 19th white force is also 24. The first black is achromatic, and the rightmost value is the average value.

Next, the relationship between the type of liquid crystal display mode and the front contrast will be described with reference to FIG. Table (a) in Fig. 10 shows data indicating the relationship between the maximum incident angle of the backlight to the liquid crystal panel 1 and the front contrast (CR) when using vertically aligned (VA) liquid crystal. Table (b) in Fig. 10 shows data showing the relationship between the maximum incident angle of the backlight to the liquid crystal panel 1 and the front contrast (CR) when the FFS (Fringe Field Switching) mode liquid crystal is used. Graph (c) in Fig. 10 plots the data in tables (a) and (b). The FFS (Fringe Field Switching) mode corresponds to the horizontal alignment mode, and is a technique that approximates the IPS (In-plane Switching) mode.

Note that, as shown in FIG. 17, measurement was performed to acquire data indicating the relationship between the maximum incident angle of the backlight and the front contrast (CR). That is, in front of the light source 51, the light shielding mask 52, the liquid crystal panel 53, and the luminance meter 54 are arranged in this order. The light source 51 is a backlight used in a normal liquid crystal panel. The light shielding mask 52 has a circular opening having a diameter d2 (mm). Further, the light shielding mask 52 and the liquid crystal panel 53 are separated by a distance L (mm).

Thus, when the light from the light source 51 that has passed through the light shielding mask 52 illuminates the liquid crystal panel 53, the luminance of the light spot S having a diameter dl (mm) formed on the liquid crystal panel 53 is measured by the luminance meter 54. A measurement system for measurement was constructed.

The backlight maximum incident angle is represented by an angle Θ shown in FIG. That is, the maximum incidence angle Θ is the angle formed by the line segment connecting the right end of the circular opening and the left end of the light spot S with respect to the normal line on the display surface of the liquid crystal panel 53 in FIG. Therefore, the backlight maximum incident angle Θ can be expressed by the following equation (1).

[0081] tan 0 = (dl + d2) / 2L

Θ = tan ^{_ 1} {(dl + d2) / 2L} (1)

By changing the distance L, the backlight maximum incident angle Θ can be adjusted.

As shown in FIG. 10, when the maximum backlight incident angle on the liquid crystal panel 1 is the same, it can be seen that the front contrast is higher in the VA mode. Also, the backlight to the LCD panel 1 It can be seen that the front contrast is more effectively improved in the VA mode when the maximum incident angle is reduced, that is, when the concentration of the backlight 3 is increased. For these reasons, in the condensing and diffusing method as in the present embodiment, it is considered that the use of the VA mode as the liquid crystal of the liquid crystal panel 1 is desirable.

Next, the relationship between the degree of light collection of the backlight 3 and the light use efficiency of the liquid crystal panel 1 will be described with reference to FIG.

That is, as shown in the table (a) of FIG. 11, the light use efficiency is obtained based on whether the lenticular lens 4 is present or not at each concentration of the backlight 3.

[0085] Here, the light utilization efficiency (%) is

Light utilization efficiency (%) = (light flux in all directions with lenticular lens) X 100 /

(Amount of luminous flux in all directions without lenticular lens)

Calculate with

Note that the liquid crystal panel with a lenticular lens is a panel with an improved viewing angle, and the panel without a lenticular lens is a conventional panel.

[0087] Further, in the present embodiment, as shown in the graph (b) of FIG. 11, each light collection degree of the backlight 3 is an angle (with respect to the front direction) that is 10% of the front luminance. The polar angle) is defined as the backlight concentration. In other words, the smaller the numerical value of the degree of condensing, the narrower the light flux of the light emitted from the backlight 3 with the higher degree of condensing.

As a result, as shown in FIG. 11 (c), it can be seen that the higher the degree of condensing of the backlight 3, the higher the light utilization efficiency of the liquid crystal panel 1.

As described above, in the liquid crystal display device 10 of the present embodiment, the lenticular lens 4 in which a plurality of aspheric lenses 4a are arranged in parallel on the same plane is provided on the front side of the liquid crystal panel 1. On the front side of the lenticular lens 4, a light shielding layer 5 having an opening 5a on the optical axis of each aspheric lens 4a is provided.

For this reason, the light emitted from the backlight 3 passes through the liquid crystal panel 1 and is collected by the lenticular lens 4 and emitted to the outside. At this time, since the opening 5a is provided on the optical axis of the aspheric lens 4a, the light passing through the opening 5a is light substantially perpendicular to the liquid crystal panel 1. On the other hand, of the light emitted from the backlight 3, the oblique light is emitted obliquely from the liquid crystal panel 1 as leakage light. This obliquely emitted light strikes the light shielding layer 5 and It does not come out on the front side.

[0092] As a result, when the liquid crystal panel 1 is viewed obliquely, there is almost no leakage light that has been present in the past, so when viewed from an oblique direction as in the prior art, the display appears whitish and the contrast is reduced. The problem is solved. In addition, the contrast when the display surface is viewed from the front and the contrast when viewed from the oblique direction are made uniform.

Accordingly, it is possible to provide the liquid crystal display device 10 that can prevent a difference in display characteristics due to a difference in observation direction.

It should be noted that the light shielding layer 5 can prevent external light from entering the liquid crystal panel 1. As a result, when the liquid crystal panel 1 is used in a bright place, it is possible to prevent a decrease in contrast due to reflected light from, for example, a pixel electrode (not shown) of the liquid crystal panel 1.

By the way, among the light emitted from the backlight 3, the oblique light is not necessarily blocked by the light shielding layer 5, but is originally leaked light. In this regard, in the present embodiment, since the light shielding layer 5 has light absorptivity, the light striking the light shielding layer 5 is absorbed by the light shielding layer 5 as it is without being reflected. Therefore, the light hitting the light shielding layer 5 can be extinguished.

[0096] As a method of forming the light-shielding light-shielding layer 5, a photosensitive black resin is applied to the flat surface opposite to the lens of the lenticular lens 4 and exposed from the lenticular lens 4 side. In addition, it is possible to employ a self-alignment method for forming the opening 5a and the light shielding portion 5b.

[0097] The method described in Patent Document 2 (Japanese Patent Laid-Open No. 2001-113538) can also be used. In this method, a photosensitive resin is applied to the flat surface opposite to the lens of the lenticular lens, and the presence or absence of adhesiveness between the exposed portion and the non-exposed portion of the photosensitive resin is used. More specifically, the light-shielding pattern is formed by transferring the black transfer layer or adhering black powder to the non-exposed portion having adhesiveness.

On the other hand, since the light that has passed through the opening 5a is light that has passed through the lenticular lens 4, there is little light in a direction other than the direction diffused by the lens layer. Therefore, depending on the lens layer The display when viewed from a direction other than the direction in which the light is diffused may be insufficient.

In this regard, in the present embodiment, the diffusion layer 6 that diffuses light is provided on the front side of the light shielding layer 5, so that the light that has passed through the opening 5 a is diffused by the diffusion layer 6. It spreads in an oblique direction. Therefore, the oblique component of the light that has passed through the opening 5a increases, so if the display is insufficient when viewed from any direction, it will not be possible!

[0100] Also, when viewed from any direction, since the light has passed vertically through the liquid crystal panel 1, the contrast is high! / And the display is! /.

[0101] Further, in the liquid crystal display device 10 of the present embodiment, the lenticular lens 4 is configured by arranging the aspherical lenses 4a having convex surfaces in a stripe shape. As a result, for example, the light in the left-right direction can be narrowed down, so that there is no difference in display characteristics due to the difference in the observation direction in the left-right direction.

[0102] In addition, in the liquid crystal display device 10 of the present embodiment, the opening 5a is formed corresponding to the aspherical lens 4a, and is formed in a stripe shape like the aspherical lens 4a. Is preferred.

[0103] Thereby, for example in the left-right direction, out of the light emitted from the knock light 3, the oblique light is obliquely emitted from the liquid crystal panel 1 as leaked light and then strikes the light shielding layer 5, so that the light shielding layer 5 It does not come out on the front side. Therefore, there will be no difference in display characteristics due to the difference in observation direction in the left-right direction.

Further, in the liquid crystal display device 10 of the present embodiment, a plurality of aspherical lenses that guide the light from the backlight 3 to the liquid crystal panel 1 are arranged in parallel between the liquid crystal panel 1 and the backlight 3. The lenticular lens 21 is provided!

Thus, the light emitted from the backlight 3 is collected by the lenticular lens 21 and then enters the liquid crystal panel 1. Therefore, of the light emitted from the backlight 3, less light is incident on the liquid crystal panel 1 at an angle. As a result, it is possible to reduce the light emitted from the liquid crystal panel 1 as leakage light obliquely.

Further, in the liquid crystal display device 10 of the present embodiment, the microlens array 40 is composed of the microlenses 40a, and the opening 5a ′ of the light shielding layer 5 is matched to the shape of the microlens 40a. It is preferably formed in a circular shape. As a result, not only left and right direction In all oblique directions, there will be no difference in display characteristics due to differences in observation direction.

In addition, in the liquid crystal display device 10 of the present embodiment, it is preferable that the knocklight 3 includes a direct light source 32. As a result, in the liquid crystal display device 10 having the backlight 3 with the direct light source 32, the force S can prevent the difference in display characteristics from occurring due to the difference in the observation direction.

[0108] In the liquid crystal display device 10 of the present embodiment, it is preferable that the operation mode of the liquid crystal panel 1 is a vertical alignment mode.

[0109] As a result, it is possible to prevent the vertical alignment mode liquid crystal from causing a difference in display characteristics due to the difference in the observation azimuth compared to the TN mode or horizontal alignment mode liquid crystal. Can be increased.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. For example, in the above embodiment, the force that did not explain the directionality of the convex surface of the lenticular lens 21 of the light collecting sheet 2. For example, as shown in FIG. It is preferable that the ridge lines of the stripe-shaped convex surface of the lenticular lens 21 constituting the light sheet 2 are orthogonal to each other.

Thereby, in the left-right direction, the light spread in the left-right direction can be substantially cut by the light shielding layer 5 and can be condensed by the lenticular lens 21 in the up-down direction. As a result, since the light emitted from the liquid crystal panel 1 is only collected light, the viewing angle characteristics are improved.

[0112] Normally, since the viewing angle characteristic in the left-right direction is more important than the up-down direction, the lenticular lens 4 is arranged in a direction diffusing in the left-right direction, that is, in a lenticular lens 4 stripe shape. It is preferable to place the convex ridge line in the vertical direction of the display screen. In order to improve the light utilization efficiency, it is preferable to condense the backlight light in the left-right direction.

As described above, in the liquid crystal display device 10 according to the present embodiment, a plurality of lenses that guide light from the backlight 3 to the liquid crystal panel 1 are arranged on the same plane between the liquid crystal panel 1 and the backlight 3. In A lenticular lens 21 is provided in parallel, and each aspherical lens 4a of the lenticular lens 4 and each lens of the lenticular lens 21 are each composed of an aspherical lens having a convex surface. The ridgeline of the convex surface and the ridgeline of the striped convex surface in the lenticular lens 21 are assumed to be perpendicular to each other by the force S.

Thereby, the lenticular lens 21 condenses the light from the backlight 3 in a direction perpendicular to the left-right direction of the liquid crystal panel 1, for example, while the lenticular lens 4 condenses the liquid crystal. The light emitted from the liquid crystal panel 1 can be collected in the horizontal direction of the panel 1.

As described above, the liquid crystal display device of the present invention is provided on the front side of the liquid crystal panel, the backlight unit that irradiates light from the back side to the front side of the liquid crystal panel, and the liquid crystal panel. A first lens layer in which a plurality of lenses are arranged in parallel on the same plane to guide light from the liquid crystal panel to the outside; and the front side of the first lens layer. And a light shielding layer having an opening on the optical axis of each lens.

[0116] Therefore, it is possible to provide a liquid crystal display device that can prevent a difference in display characteristics due to a difference in observation direction.

[0117] The specific embodiments or examples made in the detailed description section of the invention are to clarify the technical contents of the present invention, and are limited to such specific examples. Therefore, the present invention should not be interpreted in a narrow sense, and can be carried out with modifications within the spirit of the present invention and within the scope of the following claims! .

Industrial applicability

The present invention can be applied to a liquid crystal display device including a liquid crystal panel and a backlight unit.

Claims

The scope of the claims

[1] LCD panel,

A backlight unit that emits light from the back side to the front side of the liquid crystal panel, and a function that is provided on the front side of the liquid crystal panel and collects a part of the light from the liquid crystal panel and diffuses it to the outside A first lens layer formed by juxtaposing a plurality of first lenses each having the same on the same plane;

A liquid crystal display device comprising: a light shielding layer provided on the front side of the first lens layer and having an opening on each optical axis of the first lens.

2. The liquid crystal display device according to claim 1, wherein the light shielding layer has a light absorption property.

3. The liquid crystal display device according to claim 1, wherein a diffusion layer for diffusing light is provided on the front side of the light shielding layer.

4. The liquid crystal display device according to claim 1, wherein the first lens layer has a striped convex surface, and each of the first lenses is an aspherical lens having one of the convex surfaces.

5. The liquid crystal display device according to claim 4, wherein the opening of the light shielding layer is formed in a stripe shape along each convex surface of the aspheric lens.

[6] A second lens layer in which a plurality of second lenses for guiding light from the backlight unit to the liquid crystal panel is provided in parallel between the liquid crystal panel and the backlight unit. Item 1. A liquid crystal display device according to item 1.

[7] A second lens layer in which a plurality of second lenses for guiding light from the backlight unit to the liquid crystal panel are arranged in parallel on the same plane between the liquid crystal panel and the backlight unit. Is provided,

Each of the first lens layer and the second lens layer has a striped convex surface.

The first lens and the second lens are each composed of an aspheric lens having one of the convex surfaces,

2. The liquid crystal display according to claim 1, wherein the ridge line of the striped convex surface in the first lens layer and the ridge line of the striped convex surface in the second lens layer are orthogonal to each other. apparatus.

[8] Each of the first lenses is a microlens, 2. The liquid crystal display device according to claim 1, wherein the opening of the light shielding layer is formed in a circular shape that matches the shape of the microlens.

The liquid crystal display device according to claim 1, wherein the backlight unit includes a light source arranged immediately below the liquid crystal panel.

2. The liquid crystal display device according to claim 1, wherein an operation mode of the liquid crystal panel is a vertical alignment mode.

7. The liquid crystal display device according to claim 6, wherein each of the second lenses is a microlens. The liquid crystal display device according to claim 1, wherein the opening is located at each focal point or each focal line of the first lens. .

The first lens layer has a striped convex surface, and each of the first lenses is an aspherical lens having one of the convex surfaces,

The ridge line of the convex surface is arranged in the vertical direction of the display surface of the liquid crystal panel.

The liquid crystal display device according to 1.

Between the liquid crystal panel and the backlight unit, there is provided a second lens layer in which a plurality of second lenses for guiding light from the backlight unit to the liquid crystal panel are arranged in parallel on the same plane. And

The second lens layer has a stripe-like convex surface, and each of the second lenses is an aspheric lens having one of the convex surfaces,

14. The liquid crystal display device according to claim 13, wherein the stripe-shaped convex ridge line of the first lens layer and the stripe-shaped convex ridge line of the second lens layer are orthogonal to each other.