WO2006112325A1

WO2006112325A1 - Liquid crystal display

Info

Publication number: WO2006112325A1
Application number: PCT/JP2006/307741
Authority: WO
Inventors: Kenji Misono; Mitsuhiro Murata; Shinichi Miyazaki
Original assignee: Sharp Kabushiki Kaisha
Priority date: 2005-04-14
Filing date: 2006-04-12
Publication date: 2006-10-26

Abstract

Disclosed is a liquid crystal display comprising an illuminating element, a liquid crystal display panel for modulating the light emitted from the illuminating element, and a light diffusion element which is arranged on the observer side of the liquid crystal display panel for diffusing the light transmitted through the liquid crystal display panel. The liquid crystal display further comprises a first polarizer which is arranged closer to the observer than the light diffusion element.

Description

Specification

Liquid crystal display

Technical field

The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device including a light diffusing element for diffusing light emitted from a liquid crystal display panel.

Background art

In recent years, portable electronic devices typified by portable telephones and PDAs (Personal Digital Assistants) have been widely used. A liquid crystal display device having the advantages of thinness, light weight, low power consumption, and so on is used for a display portion of a portable electronic device.

[0003] Unlike self-luminous display devices such as CRTs and PDPs (plasma display panels), liquid crystal display devices do not emit light. Therefore, in a transmissive liquid crystal display device, an illumination element called a backlight is provided on the back side of the liquid crystal display element, and the liquid crystal display element controls the amount of transmitted illumination light from this knock light for each pixel. The image is displayed by.

[0004] Various types of liquid crystal display devices are known. However, some methods (for example, methods using TN type or STN type liquid crystal display elements) have the disadvantage of V when the viewing angle is narrow, and various technological developments have been made to solve this. It is done.

[0005] As a representative technique for improving the viewing angle characteristics of a liquid crystal display device, there is a method of adding an optical compensator. In addition, the light emitted from the backlight is made incident on the liquid crystal display element after increasing its directivity (parallelism), and the light that has passed through the liquid crystal display element is arranged on the front surface of the liquid crystal display element. There is also known a method of diffusing by (for example, Patent Document 1).

FIG. 22 shows a liquid crystal display device 800 disclosed in Patent Document 1. The liquid crystal display device 800 includes a liquid crystal display panel 820, a backlight 810 disposed on the back side of the liquid crystal display panel 820, and a lenticular lens sheet 830 disposed on the viewer side of the liquid crystal display panel 820. ing.

[0007] Knocklight 810 includes light source 801 and light emitted from light source 801 to liquid crystal display panel 820. The light guide plate 802 guides the light leaked from the light guide plate 802 and reflects the light to the light guide plate 802 side. The light guide plate 802 has an exit surface that emits light toward the liquid crystal display panel 820, and a back surface that faces the exit surface, and a plurality of prisms 802a are formed on the back surface.

[0008] The light emitted from the light source 801 is reflected on the liquid crystal display panel 820 side by the prism 802a on the back surface while propagating through the light guide plate 802, and is emitted from the emission surface. The prism 802a on the back surface has two inclined surfaces that are inclined at a predetermined angle different from each other with respect to the emission surface, so that the light emitted from the knock light 810 is normal to the display surface (front direction). Direction) is significantly stronger. That is, the light emitted from the backlight 810 is given high directivity.

[0009] Since the liquid crystal display panel 820 is designed to have the highest contrast ratio with respect to light incident in parallel to the normal direction of the display surface, the liquid crystal display panel By making it enter 820, the contrast ratio can be improved. Further, the light that has passed through the liquid crystal display panel 820 is diffused by the lenticular lens sheet 830, thereby widening the viewing angle. In this way, the liquid crystal display device 800 achieves both a high contrast ratio and a wide viewing angle characteristic.

Patent Document 1: Japanese Patent Laid-Open No. 9-22011

Disclosure of the invention

Problems to be solved by the invention

However, in the liquid crystal display device 800 disclosed in Patent Document 1 described above, there is a problem that the display surface is glazed and the display quality is deteriorated.

The cause of this glare is that external light (ambient light) is reflected on the surface of the lenticular lens sheet 830 or is incident on the lenticular lens sheet 830.

830 and air layer (present between wrench chiral lens sheet 830 and liquid crystal display panel 820

) Or totally reflected at the interface.

The present invention has been made in view of the above problems, and an object thereof is to suppress glare of a display surface in a liquid crystal display device having a light diffusing element on the front surface of a liquid crystal display panel.

Means for solving the problem A liquid crystal display device according to the present invention is disposed on an observer side of a lighting element, a liquid crystal display panel that modulates light emitted from the lighting element force, and passes through the liquid crystal display panel. A light diffusing element for diffusing light, and a first polarizing element having a transmission axis parallel to the first direction and disposed closer to the observer side than the light diffusing element. The above objective is achieved.

[0014] In a preferred embodiment, the liquid crystal display device according to the present invention has a transmission axis parallel to the second direction, and is arranged between the liquid crystal display panel and the light diffusing element. A polarizing element is further provided, and the first direction and the second direction are substantially parallel.

[0015] In a preferred embodiment, an angle formed by the first direction and the second direction is 5 ° or less.

[0016] In a preferred embodiment, an angle formed by the first direction and the second direction is 2 ° or less.

In a preferred embodiment, the liquid crystal display device according to the present invention further comprises an antireflection film disposed between the liquid crystal display panel and the light diffusing element.

[0018] In a preferred embodiment, the antireflection film includes a plurality of layers having different refractive indexes.

[0019] In a preferred embodiment, the liquid crystal display device according to the present invention includes a first 1Z4 wavelength plate disposed between the first polarizing element and the light diffusing element, and the light diffusing element. And a second 1Z4 wave plate disposed between the liquid crystal display panel and the liquid crystal display panel.

In a preferred embodiment, the slow axis of the first 1Z4 wavelength plate and the slow axis of the second 1Z4 wavelength plate are substantially orthogonal.

[0021] In a preferred embodiment, the slow axis of the first 1Z4 wave plate forms an angle of approximately 45 ° with the first direction.

[0022] In a preferred embodiment, the liquid crystal display device according to the present invention further includes a third polarizing element disposed on the opposite side of the liquid crystal display panel from the observer side.

According to a preferred embodiment, the liquid crystal display device according to the present invention further comprises a phase difference compensation element disposed between the liquid crystal display panel and the third polarizing element, and A phase difference compensation element is provided between the liquid crystal display panel and the light diffusing element. In a preferred embodiment, the liquid crystal display device according to the present invention includes a phase difference compensating element disposed between the first polarizing element and the liquid crystal display panel, and observation of the phase difference compensating element. An adhesive layer formed on the surface opposite to the person side, and the adhesive layer functions as the light diffusing element.

[0025] In a preferred embodiment, the liquid crystal display device according to the present invention includes a further light diffusing element disposed between the light diffusing element and the first polarizing element.

[0026] In a preferred embodiment, the liquid crystal display device according to the present invention further includes a transparent resin layer disposed between the light diffusing element and the further light diffusing element.

[0027] In a preferred embodiment, the transparent resin layer is a retardation compensation element.

[0028] According to a preferred embodiment, the liquid crystal display device according to the present invention includes a first adhesive layer formed on a surface opposite to an observer side of the retardation compensation element, and the A second adhesive layer formed on a surface opposite to the viewer side of the first polarizing element, wherein the first adhesive layer functions as the light diffusing element, and the second adhesive layer Functions as the further light diffusion element.

[0029] In a preferred embodiment, the liquid crystal display panel includes a pair of substrates, and the light diffusion element is provided immediately above the viewer-side substrate of the pair of substrates. .

[0030] According to a preferred embodiment, the light diffusing element includes a lens sheet having a plurality of lenses or a prism sheet having a plurality of prisms.

[0031] In a preferred embodiment, the light diffusing element includes a diffusion film having a matrix formed of a resin material and particles dispersed in the matrix and having a refractive index different from that of the matrix. including.

[0032] Alternatively, a liquid crystal display device according to the present invention is disposed on an illuminating element, a liquid crystal display panel that modulates light emitted from the illuminating element, and an observer side of the liquid crystal display panel. A liquid crystal display device comprising: a first light diffusing element that diffuses light that has passed; a polarizing element that is disposed closer to an observer than the first light diffusing element; and A second light diffusing element disposed between the light diffusing element and the polarizing element is further provided, whereby the above object is achieved. In a preferred embodiment, the liquid crystal display device according to the present invention further includes a transparent resin layer disposed between the first light diffusing element and the second light diffusing element.

[0034] In a preferred embodiment, the transparent resin layer is a retardation compensation element.

[0035] According to a preferred embodiment, the liquid crystal display device according to the present invention includes a first pressure-sensitive adhesive layer formed on a surface opposite to the viewer side of the retardation compensation element, and the polarization A second adhesive layer formed on the surface opposite to the observer side of the element, wherein the first adhesive layer functions as the first light diffusing element, and the second adhesive layer Functions as the second light diffusing element.

In a preferred embodiment, the liquid crystal display panel includes a pair of substrates, and the first light diffusing element is provided immediately above the viewer-side substrate of the pair of substrates. It has been.

[0037] In a preferred embodiment, the illumination element has a luminance in a direction that forms an angle of 30 ° or more with respect to the display surface normal direction such that the luminance is 13% or less of the luminance in the display surface normal direction. It has a light distribution.

[0038] In a preferred embodiment, the illumination element has a luminance in a direction that forms an angle of 30 ° or more with respect to the normal direction of the display surface, which is 3% or less of the luminance in the normal direction of the display surface. Have a good light distribution.

The invention's effect

[0039] Since the liquid crystal display device according to the present invention includes a polarizing element disposed closer to the observer than the light diffusing element !, external light (ambient light) incident on the light diffusing element from the observer side is provided. Is reduced. Therefore, reflection of external light on the surface of the light diffusing element and total reflection of external light incident on the light diffusing element at the interface between the light diffusing element and other layers are reduced. As a result, glare on the display surface is suppressed and high-quality display is realized.

Brief Description of Drawings

FIG. 1 is a cross-sectional view schematically showing a liquid crystal display device 100 in a preferred embodiment of the present invention.

FIG. 2 is a diagram showing an example of the arrangement of transmission axes of three polarizing elements 40a, 40b, and 40c included in the liquid crystal display device 100. 3) A side view showing an example of a specific configuration of the illumination element (backlight) 10 included in the liquid crystal display device 100. FIG.

4) A diagram for explaining the function of the total reflection prism sheet 3 provided in the illumination element 10. FIG.

圆 5] A side view showing an example of another light diffusing element used in the liquid crystal display device of the present invention. 圆 6] A side view showing an example of another light diffusing element used in the liquid crystal display device of the present invention. 7] (a) and (b) are side views showing examples of other light diffusing elements used in the liquid crystal display device of the present invention.

[FIG. 8] (a), (b), and (c) are graphs showing examples of light distribution of light emitted from the illumination element 10.

[9] (a), (b), and (c) are diagrams showing examples of viewing angle compensation patterns by a compensation layer (a liquid crystal layer and a phase difference compensation element).

FIG. 10 is a cross-sectional view schematically showing another liquid crystal display device 200 in a preferred embodiment of the present invention.

FIG. 11] A sectional view schematically showing another liquid crystal display device 300 in a preferred embodiment of the present invention.

FIG. 12 is a cross-sectional view schematically showing another liquid crystal display device 400 according to a preferred embodiment of the present invention.

[13] FIG. 13 is a diagram for explaining a problem caused by external light transmitted through the first polarizing plate 40a.

FIG. 14 is a diagram showing a slow axis arrangement of first 1Z4 wavelength plate 60a and second 1Z4 wavelength plate 60b included in liquid crystal display device 400.

15] A diagram for explaining the function of the first 1Z4 wave plate 60a.

FIG. 16 is a diagram illustrating functions of a first 1Z4 wavelength plate 60a and a second 1Z4 wavelength plate 60b.

17] A cross-sectional view schematically showing another liquid crystal display device 500 according to a preferred embodiment of the present invention. FIG.

FIG. 18 is a side view showing another example of the specific configuration of the illumination element (backlight) 10.

FIG. 19 is a diagram for explaining the function of a lens sheet functioning as a reflective polarizing plate.

FIG. 20 is a cross-sectional view schematically showing another liquid crystal display device 600 in a preferred embodiment of the present invention.

[FIG. 21] (a) is a diagram schematically showing the progression of light in a configuration provided with a single light diffusing element, and (b) is a diagram showing the progression of light in a configuration provided with a plurality of light diffusing elements FIG.

FIG. 22 is a perspective view schematically showing a conventional liquid crystal display device 800.

Explanation of symbols

1 Light source

2 Light guide plate

3 Prism sheet

3a prism

10 Lighting element (backlight)

20 LCD panel

21, 22, 22 'substrate

23 Liquid crystal layer

24 Color filter

30, 30A Light diffusing element (Lenticular lens sheet)

30B diffusion film

30a Lens layer

30b planarization layer

30 'Further light diffuser

31 Wrench Kiyura lens

33 Matrix

34 particles

40a Polarizer (first polarizer) 40b Polarizer (second polarizer)

40c Polarizing plate (third polarizing plate)

50a, 50b, 50c Phase compensation element

60a First 1Z4 wave plate

60b Second 1Z4 wave plate

100, 200, 300, 400, 500, 600 Liquid crystal display

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments.

[0043] (Embodiment 1)

FIG. 1 shows a liquid crystal display device 100 according to this embodiment. Liquid crystal display 100

1, a liquid crystal display panel 20, a lighting element (backlight) 10 disposed on the back side of the liquid crystal display panel 20, and a light diffusing element disposed on the viewer side of the liquid crystal display panel 20

And 30.

The liquid crystal display panel 20 includes a pair of substrates 21 and 22 and a liquid crystal layer 23 provided therebetween. On the surface of the substrates 21 and 22 on the liquid crystal layer 23 side, electrodes for applying a voltage to the liquid crystal layer 23 and alignment films (both not shown) for defining the alignment direction of the liquid crystal layer 23 are formed. Yes. In the present embodiment, the color filter 24 is provided on the liquid crystal layer 23 side of the substrate 22 disposed on the viewer side.

[0045] Polarizers 40b and 40c are respectively disposed on the viewer side and the back side of the liquid crystal display panel 20 (that is, the side opposite to the viewer side). Further, a polarizing plate 40 a is also arranged on the viewer side of the light diffusing element 30. That is, the liquid crystal display device 100 includes three polarizing elements. Hereinafter, the polarizing plate 40a disposed closer to the viewer than the light diffusing element 30 is referred to as a “first polarizing plate”, and the polarizing plate 4 Ob disposed between the light diffusing element 30 and the liquid crystal display panel 20 Is referred to as the “second polarizing plate”, and the polarizing plate 40c disposed on the back side of the liquid crystal display panel 20 (ie, between the liquid crystal display panel 20 and the illumination element 10) is referred to as the “third polarizing plate”. .

[0046] As shown in FIG. 2, the first polarizing plate 40a and the second polarizing plate 40b are arranged such that the transmission axes TA are substantially parallel to each other. The third polarizing plate 40c is a surface of the liquid crystal display panel 20. In accordance with the indicated mode, the transmission axis TA is arranged at an arbitrary angle with the transmission axis TA of the first polarizing plate 40a and the second polarizing plate 40b. For example, when displaying normally white in the TN mode, the third polarizing plate 40c has a transmission axis TA of the first polarizing plate 40a and the second polarizing plate 40b as illustrated in FIG. Arranged so as to be substantially orthogonal to the transmission axis TA.

[0047] By modulating the light emitted from the illumination element 10 with the liquid crystal display panel 20, the amount of the light that passes through the first and second polarizing plates 40a and 40b and is emitted to the viewer side is different for each pixel. The image is displayed as a result.

[0048] Between the second polarizing plate 40b and the liquid crystal display panel 20, and between the third polarizing plate 40c and the liquid crystal display panel 20, respectively, ^ phase difference compensation elements 50a and 50b are arranged. Yes. As the phase difference compensating elements 50a and 50b, various known phase difference plates are used. Note that a phase difference compensation element may be provided only between one of the second polarizing plate 40b and the liquid crystal display panel 20 and between the third polarizing plate 40c and the liquid crystal display panel 20.

FIG. 3 shows an example of a specific configuration of the illumination element (backlight) 10. A lighting element 10 shown in FIG. 3 includes a light source 1 and a light guide plate 2 that guides light emitted from the light source 1 to the liquid crystal display panel 20. The light source 1 is, for example, a light emitting diode (LED) or a cold cathode tube. The light guide plate 2 is formed with a structure for emitting light emitted from the light source 1 and entering the light guide plate 2 to the liquid crystal display panel 20 side. For example, a prism or a texture is formed on at least one of the two main surfaces of the light guide plate 2.

The illumination device 10 further includes a prism sheet 3 that controls the directivity of light emitted from the light guide plate 2. The prism sheet 3 that functions as a directivity control element is provided between the light guide plate 2 and the liquid crystal display panel 20.

[0051] The prism sheet 3 has a plurality of prisms 3a formed on the main surface on the light guide plate 2 side. As shown in FIG. 4, the light emitted from the light guide plate 2 is subjected to a total reflection phenomenon. Use it to face the normal direction of the display surface. Thus, the light emitted from the light guide plate 2 is given high directivity by the prism sheet 3. The prism sheet 3 exemplified here is also referred to as a “total reflection prism sheet”. In addition, if a light guide plate with a microphone aperture lens array formed on the main surface based on the normal vector theory is used as the light guide plate 2, the light is guided by total reflection from the micro lens. It is preferable because the light propagating in the plate can be efficiently emitted to the total reflection prism sheet (directivity control element) 3! /.

[0052] If the light emitted from the illumination device 10 has high directivity, the light passing through the liquid crystal layer 23 can be modulated uniformly (that is, the light passing through the liquid crystal layer 23 is uniform). Therefore, the viewing angle dependency of display quality due to the refractive index anisotropy of liquid crystal molecules can be reduced. The light that has passed through the liquid crystal layer 23 has a high directivity and a large bias in luminance (the luminance in the normal direction of the display surface is extremely high and the luminance in the oblique direction is low). The diffusion of brightness reduces the luminance bias, thereby widening the viewing angle.

As shown in FIG. 1, the light diffusing element 30 in this embodiment is a lenticular lens sheet having a plurality of semi-cylindrical lenticular lenses 31. A flat layer 30b is formed on the lens layer 30a including a plurality of lenticular lenses 31, and the refractive index n of the lens layer 30a and the refractive index n of the flattening layer 30b are n <n. Set to satisfy the relationship

1 2 1 2

Yes.

The light that has passed through the liquid crystal display panel 20 and entered the light diffusing element 30 is diffused by the lenticular lens 31. Since the lenticular lens 31 mainly diffuses light in a direction perpendicular to the extending direction thereof, the extending direction of the lenticular lens 31 depends on the light distribution of the light emitted from the illumination element 10. Set as appropriate. The extending direction of the lenticular lens 31 is set so as to be substantially orthogonal to the extending direction of the prism 3a of the prism sheet 3, for example.

As the light diffusing element 30, various known elements can be used. FIG. 1 illustrates the configuration in which the light diffusing element 30 is provided with the convex lens 31, but a concave lens 31 ′ may be provided as in the light diffusing element 30A shown in FIG. Further, as the light diffusing element 30, a prism sheet having a plurality of prisms (for example, a total reflection type prism sheet) may be used.

Furthermore, a diffusion film 30B using internal scattering as shown in FIG. 6 may be used. The diffusing film 30B (sometimes referred to as a “diffuser”) has a matrix 33 formed of a resin material force and a matrix dispersed in the matrix 33 as shown in a partially enlarged view in FIG. Particles 34 having a refractive index different from that of the particles 33.

In addition, as shown in FIGS. 7A and 7B, a combination of a diffusion film 30B and a lens sheet 30 or 30A may be used. Alternatively, a combination of diffusion film 30B and a prism sheet may be used! While the lens sheet and the prism sheet diffuse light anisotropically, the diffusion film 30B diffuses light relatively isotropically. Therefore, the desired light distribution can be easily realized by using these in combination.

[0058] As described above, the light diffusing element 30 may be formed by stacking a plurality of light diffusing layers having different diffusing functions. The plurality of light diffusion layers are bonded through, for example, an adhesive. The plurality of light diffusion layers and the pressure-sensitive adhesive preferably have a refractive index set so that the refractive index becomes lower toward the observer side. The liquid crystal display panel 20, the light diffusing element 30, the polarizing plates 40a, 40b, and 40c, and the phase difference compensating elements 50a and 50b are also typically bonded together with an adhesive.

[0059] As described above, in the liquid crystal display device 100, light having high directivity (parallelism) emitted from the illumination element 10 is incident on the liquid crystal display panel 20, and light that has passed through the liquid crystal display panel 20 is liquid crystal display panel. The light is diffused by the light diffusing element 30 arranged on the 20 observer side. Therefore, display with a high contrast ratio and a wide viewing angle can be performed.

[0060] In the liquid crystal display device 100 according to the present invention, the first polarizing plate 40a is disposed closer to the viewer side than the light diffusing element 30, so that external light (surrounding) incident on the light diffusing element 30 from the viewer side is arranged. Light) is absorbed by the first polarizing plate 40a, and the amount thereof is reduced. Therefore, reflection of external light on the surface of the light diffusing element 30 and total reflection of external light incident on the light diffusing element 30 at the interface between the light diffusing element 30 and another layer are reduced. Therefore, glare on the display surface is suppressed and high-quality display is realized.

[0061] In addition, in a conventional liquid crystal display device having a light diffusing element on the observer side of the liquid crystal display panel, when the light passing through the liquid crystal display panel enters the light diffusing element, the liquid crystal display panel is caused by backscattering There is directional light on the side. This light is called stray light and causes the display quality to deteriorate.

In the liquid crystal display device 100 according to the present embodiment, since the second polarizing plate 40b is disposed between the liquid crystal display panel 20 and the light diffusing element 30, such stray light becomes the second polarized light. Reduced by being absorbed by plate 40b. As a result, deterioration of display quality due to stray light is suppressed. Furthermore, if the color filter 24 is provided on the observer-side substrate 22 as in this embodiment, part of the stray light can be absorbed by the color filter 24, thereby suppressing deterioration in display quality. High effect.

[0063] In the case of providing the second polarizing plate 40b for suppressing the deterioration of display quality due to stray light in addition to the first polarizing plate 40a for suppressing the deterioration of display quality due to reflection of external light, In order to efficiently use the light that has passed through the liquid crystal display panel 20, it is preferable that the transmission axis TA of the first polarizing plate 40a and the transmission axis TA of the second polarizing plate 40b are substantially parallel. . More specifically, the angle formed by the transmission axis TA of the first polarizing plate 40a and the transmission axis TA of the second polarizing plate 40b is preferably 5 ° or less, and preferably 2 ° or less. More preferred. Table 1 shows the relationship between the angle formed by the transmission axis TA and the display characteristics. Table 1 shows the display in color STN mode. 1. The measurement results are shown when using an 8-inch panel and driving at 1Z160 duty.

[0064] [Table 1]

[0065] As shown in Table 1, when the angle formed by the transmission axis TA is within 5 °, the angle exceeds 5 ° or when the first polarizing plate 40a and the light diffusing element 30 are not provided. In comparison, it can be seen that good display characteristics are obtained with high brightness, contrast ratio, NTSC ratio, and viewing angle characteristics. It can also be seen that even better display characteristics can be obtained when the angle formed by the transmission axis TA is within 2 °.

[0066] As the illumination element 10, it is preferable to use an element that can emit light with higher directivity in order to obtain a higher contrast ratio than can be used with various backlights. Specifically, the direction in which the illumination element 10 forms an angle of 30 ° or more with respect to the normal direction of the display surface If the distribution of light distribution is such that the brightness at 3% is less than 3% of the brightness in the normal direction of the display surface, a sufficiently high contrast ratio can be easily realized.

[0067] FIGS. 8A and 8B show examples of preferable light distributions of the illumination element 10. FIG. In the light distribution shown in Fig. 8 (a), the luminance power S in the normal direction of the display surface S suddenly decreases as the highest angle increases. In contrast, in the light distribution shown in Fig. 8 (b), a relatively high luminance is maintained from the normal direction of the display surface to around 30 °. In both of the light distributions shown in Fig. 8 (a) and (b), the luminance in the direction forming an angle of 30 ° or more with respect to the normal direction of the display surface is the luminance in the normal direction of the display surface (0 °). 3% or less. Therefore, an excellent display quality can be obtained by using the illumination element 10 having such a light distribution.

Another example of the light distribution is shown in FIG. 8 (c). In the light distribution shown in Fig. 8 (c), the luminance in the direction that makes an angle of 30 ° or more with respect to the normal direction of the display surface is 8% to the luminance in the normal direction of the display surface (0 °). 13% or less. Even when the illumination element 10 having such a light distribution is used, it is sufficiently excellent by appropriately selecting a pattern of optical compensation (viewing angle compensation) by the liquid crystal layer 23 and the phase difference compensation elements 50a and 50b. Display quality can be obtained.

FIGS. 9 (a), (b) and (c) show examples of viewing angle compensation patterns using a liquid crystal layer and a phase difference compensation element (collectively referred to as “compensation layer”). Figures 9 (a), (b) and (c) show the viewing angles when light of a predetermined light distribution is incident on a liquid crystal display device having compensation layers with different compensation characteristics. In the figure, the parts marked with a tick and a pinch indicate an angle range in which a contrast ratio of a predetermined value or more can be secured. This part is called the contrast cone (CRC) below.

[0070] The contrast cone shown in FIG. 9 (a) (hereinafter referred to as "CRC1") is wider in the left-right direction than in the vertical direction, and has a wider viewing angle in the left-right direction than in the vertical direction. Means. The contrast cone shown in Fig. 9 (b) (hereinafter referred to as "CRC2") is wider in the horizontal direction than in the vertical direction, but the difference is smaller in the horizontal direction than in the vertical direction, which is smaller than CRC1. This means that although the viewing angle in the direction is wide, the difference is smaller than in the case shown in Fig. 9 (a). In addition, the contrast cone shown in FIG. 9 (c) (hereinafter referred to as "CRC3") ) Means that the vertical and horizontal widths are substantially the same, and the viewing angle is almost the same in the vertical and horizontal directions. CRC1, CRC2 and CRC3 all have their centers offset upward, meaning that the viewing angle in the upward direction is wider than the viewing angle in the downward direction.

[0071] The light distribution shown in Figs. 8 (a), (b), and (c) (referred to as light distributions A, B, and C, respectively) and Figs. 9 (a), (b), and (c Table 2 shows the suitability of the combination of CRC1, CRC2 and CRC3 shown in). In Table 2, “◯” indicates that the combination is better than “△”, and “◎” indicates that the combination is better.

[0072] [Table 2]

[0073] As shown in Table 2, the light distribution A shown in FIG. 8 (a) and the light distribution B shown in FIG. 8 (b) are the same as the contrast cones of CRC1, CRC2, and CRC3. Can be combined very well. Further, it can be seen from Table 2 that the light distribution C shown in FIG. 8 (c) is more preferably combined with CRC3 which is preferably combined with CRC2 than CRC1.

[0074] As can be seen from these facts, in order to suitably perform the viewing angle compensation, the partial force of the peak of the light distribution of the lighting element 10 is substantially reduced to the contrast cone (angle range indicated by the contrast cone). Preferably they match or are located within the contrast cone. If the peak of the light distribution distribution protrudes outside the contrast cone, the viewing angle may not be sufficiently widened.

The directivity of the degree shown in FIG. 8 (c) can be easily realized by using, for example, the illumination element 10 provided with the total reflection type prism sheet 3 shown in FIG. Further, the directivity of the degree shown in FIGS. 8A and 8B can be realized by using knock lights disclosed in US Pat. No. 5,949,933 and US Pat. No. 5,598,281. The above-mentioned US Pat. No. 5,949,933 discloses an edge light type backlight in which a lenticular microprism is provided on the main surface of a light guide plate. Also the above US Japanese Patent No. 5598281 discloses a direct type backlight in which light emitted from a light source is incident on a microcollimator and a microlens through an opening.

[0076] The contrast cone shown in Fig. 9 (a) can be realized by using, for example, a retardation plate NRF (Nz coefficient is 1.0) manufactured by Nitto Denko Corporation. In addition, the contrast cone shown in FIG. 9 (b) can be realized by using, for example, a phase difference plate NRZ (Nz coefficient is 0.5 to 0.8) manufactured by Nitto Denko Corporation. Further, the contrast cone shown in FIG. 9 (c) can be realized, for example, by using a phase difference plate NRZ (Nz coefficient force ^ ˜0.4) manufactured by Nitto Denko Corporation. Note that the Nz coefficient is one of the indexes representing the magnitude relationship between the refractive index components n, n, n of the retardation plate.

In the present embodiment, the force provided by the second polarizing plate 40b in order to suppress the deterioration in display quality due to stray light, instead of the second polarizing plate 40b, the liquid crystal display panel 20 and the light diffusing element. An antireflection film may be arranged between the child 30. By providing an antireflection film between the liquid crystal display panel 20 and the light diffusing element 30, reflection of stray light can be suppressed, and deterioration of display quality due to stray light can be suppressed. As the antireflection film, various known films can be used as a so-called AR film. For example, a multilayer interference film including a plurality of layers having different refractive indexes can be used.

[0078] (Embodiment 2)

FIG. 10 shows a liquid crystal display device 200 according to this embodiment. The liquid crystal display device 200 is different from the liquid crystal display device 100 according to the first embodiment in that a polarizing element is provided between the liquid crystal display panel 20 and the light diffusing element 30. That is, the liquid crystal display device 200 corresponds to the liquid crystal display device 100 according to Embodiment 1 in which the second polarizing plate 40b is omitted.

In the liquid crystal display device 200 as well, since the polarizing plate 40a is arranged on the viewer side with respect to the light diffusing element 30, the display surface glare caused by external light incident on the light diffusing element 30 from the viewer side. Suppression can be suppressed. Thus, by providing the polarizing plate 40a at least on the viewer side of the light diffusing element 30, it is possible to perform a display with higher quality than before.

[0080] When a polarizing element is not provided between the liquid crystal display panel 20 and the light diffusing element 30 as in the present embodiment, generation of stray light due to back scattering of the light diffusing element 30 is reduced as much as possible. Is preferred.

[0081] For example, a lens sheet can be designed so that the total reflection angle in the lens becomes smaller, A diffusion film having anisotropic diffusion characteristics with reduced diffusibility to light incident from an oblique direction is used, or a difference in refractive index between layers constituting the light diffusing element 30 is reduced (for example, Δη = 0. 1 to 0.2), the generation of stray light can be reduced.

Embodiment 3

FIG. 11 shows a liquid crystal display device 300 according to this embodiment. While the liquid crystal display device 200 in the second embodiment includes the phase difference compensation elements 50a and 50b on both the back side and the viewer side of the liquid crystal display panel 20, the liquid crystal display device 300 in the present embodiment Although the phase difference compensation element 50c is provided on the back side of the liquid crystal display panel 20, the phase difference compensation is provided between the observer side of the liquid crystal display panel 20, that is, between the liquid crystal display panel 20 and the light diffusing element 30. It does not have an element. In the present embodiment, the viewer-side substrate 22 ′ of the liquid crystal display panel 20 is thinner than the viewer-side substrate 22 of the liquid crystal display panel 20 in the second embodiment.

Also in the liquid crystal display device 300, since the polarizing plate 40a is disposed on the viewer side with respect to the light diffusing element 30, the display surface glare caused by external light incident on the light diffusing element 30 from the viewer side. Suppression can be suppressed.

Further, in the liquid crystal display device 300, the polarizing plate 40b and the phase difference compensation element 50a that are disposed between the liquid crystal display panel 20 and the light diffusing element 30 in the liquid crystal display device 100 of Embodiment 1 are omitted. ing. Therefore, the distance from the color filter 24 that is the origin of the image to the light diffusing element 30 is shortened, and the display blur is improved accordingly. In addition, the entire liquid crystal display device can be made thinner.

[0085] Further, as in this embodiment, by using the thin substrate 22 'as the substrate on the viewer side of the liquid crystal display panel 20, display blurring is further improved, and the liquid crystal display device is further thinned. Can be achieved.

[0086] Since the light diffusing element 30 and the polarizing plate 40a are laminated on the viewer side of the liquid crystal display panel 20, the substrate 22 'on the viewer side having a good mechanical strength balance is thinned (for example, on the back side). Even if the substrate 21 is 1Z10 or more and 4Z5 or less), sufficient rigidity can be secured.

[0087] In general, the phase difference compensation element is provided on the back side and the observation side of the liquid crystal display panel. It is optically equivalent even if it is arranged on either side. Therefore, if the retardation to be given by a plurality of phase difference compensation elements can be given by one phase difference compensation element, the back side of the liquid crystal display panel 20, that is, the liquid crystal display, as in this embodiment. Even if the retardation compensation element 50c is provided only between the panel 20 and the polarizing plate 40c on the back side, the retardation compensation can be performed without any problem. As the retardation compensation element 50c disposed between the liquid crystal display panel 20 and the polarizing plate 4 Oc on the back side, for example, an integrated laminated retardation plate or commercially available from Mitsubishi Corporation Screw; a phase difference plate can be used.

[Embodiment 4]

FIG. 12 shows a liquid crystal display device 400 according to this embodiment. The liquid crystal display device 400 includes a pair of 1Z4 wave plates 60a and 60b provided so as to face each other with the light diffusing element 30 therebetween, and thus differs from the liquid crystal display device 100 in the first embodiment. .

Similarly to the liquid crystal display device 100, the liquid crystal display device 400 includes a first polarizing plate 40a disposed on the viewer side with respect to the light diffusing element 30, and the liquid crystal display panel 20 and the light diffusing element 30. Since the second polarizing plate 40b is disposed on the display, the deterioration of display quality can be suppressed.

The liquid crystal display device 400 further includes a first 1Z4 wavelength plate 60a disposed between the first polarizing plate 40a and the light diffusing element 30, and between the light diffusing element 30 and the liquid crystal display panel 20. And a second 1Z4 wavelength plate 60b. Therefore, it is possible to suppress deterioration of display quality due to reflection of the linearly polarized light component transmitted through the first polarizing plate 40a out of the external light by the light diffusing element 30, and to improve the display quality at any time. Hereinafter, the reason will be described.

First, a problem that occurs when the pair of 1Z4 wavelength plates 60a and 60b is not provided will be described with reference to FIG.

[0092] The external light incident on the light diffusing element 30 from the observer side is absorbed by the first polarizing plate 40a, but a part thereof, more specifically, the first polarized light as shown in FIG. The linearly polarized light component that vibrates in the direction parallel to the transmission axis TA of the plate 40a is transmitted through the first polarizing plate 40a. The linearly polarized light transmitted through the first polarizing plate 40a passes through the light diffusing element 30 (for example, at the interface between the planarizing layer 30b and the lens layer 30a or the interface between the lens layer 30a and the layer immediately below it). Part of the light is reflected, passes through the first polarizing plate 40a again, and is emitted to the viewer side. . Therefore, the display quality is degraded.

FIG. 14 shows the arrangement of the slow axes of the first 1Z4 wavelength plate 60a and the second 1Z4 wavelength plate 60b in the present embodiment. As shown in FIG. 14, the slow axis SA of the first 1Z4 wavelength plate 60a and the slow axis SA of the second 1Z4 wavelength plate 60b are substantially orthogonal. Further, the slow axis SA of the first 1Z4 wavelength plate forms an angle of about 45 ° with the transmission axis TA of the first polarizing plate 40a.

[0094] The functions of the first 1Z4 wave plate 60a and the second wave plate 60b arranged as described above will be described with reference to FIGS.

As shown in FIG. 15, only the linearly polarized light that vibrates in the direction parallel to the transmission axis TA of the first polarizing plate 40a out of the external light incident on the liquid crystal display device 400 as the observer side force is the first. Transmits through polarizing plate 40a. The linearly polarized light transmitted through the first polarizing plate 40a is converted into circularly polarized light (here, right circularly polarized light) by the first quarter-wave plate 60a. A part of the circularly polarized light emitted from the first 1Z4 wavelength plate 60a is reflected when passing through the light diffusing element 30, but at this time, it becomes reversely circularly polarized light (here, left circularly polarized light). When this reversely circularly polarized light passes through the first 1Z4 wavelength plate 60a again, it is converted into linearly polarized light having a polarization direction orthogonal to the polarization direction when it first enters the first 1Z4 wavelength plate 60a. This linearly polarized light has its polarization direction orthogonal to the transmission axis TA of the first polarizing plate 40a, so it is absorbed by the first polarizing plate 40a and hardly emitted to the viewer side. Therefore, the display quality is prevented from being deteriorated due to the external light transmitted through the first polarizing plate 40a.

[0096] Also, the first 1Z4 wavelength plate 60a and the second 1Z4 wavelength plate 60b are arranged so that the slow axes SA are substantially orthogonal to each other. Therefore, the display modulated by the liquid crystal display panel 20 is provided. The retardation provided by the first 1Z4 wavelength plate 60a and the second 1Z4 wavelength plate 60b with respect to the light cancels each other. Specifically, as shown in FIG. 16, the display light transmitted through the second polarizing plate 40b (linearly polarized light having a polarization direction parallel to the transmission axis TA of the second polarizing plate 40b) is the second 1 Z4 The light is once converted into circularly polarized light (here, right circularly polarized light) by the wave plate 60b, and then converted into the original linearly polarized light by the first 1Z4 wave plate 60a. Therefore, the first 1Z4 wave plate 60a and the second 1Z4 wave plate 60b are equivalent to V, which does not exist optically for display light, and will not adversely affect the display light! / ,.

[0097] As described above, in the liquid crystal display device 400 of the present embodiment, the light passes through the first polarizing plate 40a. In addition, since the deterioration of display quality due to external light can be suppressed without adversely affecting the display light, the display quality can be further improved.

In the present embodiment, various elements can be used as the light diffusing element 30. In addition to the elements illustrated in FIG. 12, for example, FIG. 5, FIG. 6, FIG. The one shown in (b) may be used. Further, as described in the first embodiment, an antireflection film may be provided instead of the second polarizing plate 40b, and the second polarizing plate 40b is omitted as in the liquid crystal display device 200 in the second embodiment. Even so.

[0099] Further, in the configuration described above, the third polarizing plate 40c is provided on the opposite side of the liquid crystal display panel 20 from the observer side. However, as the illumination element 10, linearly polarized light is selectively used. In the case where an illumination element that can emit light is used, the third polarizing plate 40c may be omitted. However, from the viewpoint of securing a high degree of polarization with a simple configuration, the method of providing the third polarizing plate 40c is advantageous.

[0100] (Embodiment 5)

FIG. 17 shows a liquid crystal display device 500 according to this embodiment. Whereas the liquid crystal display device 200 according to the second embodiment includes the light diffusion element 30 between the phase difference compensation element 50a on the observer side and the first polarizing plate 40a, the liquid crystal display device according to the present embodiment 500 includes a light diffusing element 30 between the liquid crystal display panel 20 and the phase difference compensating element 50a on the observer side. In this manner, the light diffusing element 30 may be disposed closer to the liquid crystal display panel 20 than the phase difference compensating element 50a.

Specifically, the light diffusing element 30 in the present embodiment is provided immediately above the viewer-side substrate 22 of the pair of substrates 21 and 22 of the liquid crystal display panel 20. Thus, if the light diffusing element 30 is provided immediately above the substrate 22, display blurring can be prevented. Hereinafter, the reason will be described.

[0102] Although the illumination element 10 emits light with high directivity, it actually emits light not only in the front direction but also in an oblique direction. Therefore, when the distance between the pixel and the light diffusion element 30 is long, each The light passing through these pixels enters the light diffusing element 30 with a relatively large spread. As a result, light from different pixels may be mixed and display blur may occur. On the other hand, when the light diffusing element 30 is provided immediately above the substrate 22 as in the present embodiment, there is no other member between the light diffusing element 30 and the substrate 22, and thus the liquid crystal display panel 20. The distance between the pixel and the light diffusing element 30 can be shortened. For this reason, it is possible to prevent display blurring in which light from different pixels is mixed.

[0104] It is preferable that the light diffusing element 30 also serves as an adhesive layer for bonding the phase difference compensating element 50a and the liquid crystal display panel 20. That is, it is preferable that the adhesive layer formed on the surface of the phase difference compensation element 50a (the surface opposite to the observer side) functions as the light diffusing element 30. By adopting such a configuration, the thickness can be further reduced. In addition, the manufacturing process can be reduced.

As the light diffusing element 30 that also functions as an adhesive layer, for example, a light diffusing layer using internal scattering as shown in FIG. 6 can be used. By dispersing particles (for example, plastic beads) having a refractive index different from that of the pressure-sensitive adhesive in the pressure-sensitive adhesive, the light diffusing element 30 functioning as the pressure-sensitive adhesive layer can be obtained.

Subsequently, FIG. 18 shows another example of a specific configuration of the illumination element (backlight) 10. The illumination element 10 includes a light source 1 and a light guide plate 2 that guides light emitted from the light source 1 to the liquid crystal display panel 20.

[0107] On the back side of the light guide plate 2, the reflection sheet 4 is arranged. The reflection sheet 4 reflects the light leaked from the light guide plate 2 to the back side toward the light guide plate 2 again.

Further, on the front side of the light guide plate 2, a diffusion sheet 5, a lower lens sheet 6, and an upper lens sheet 7 are arranged in this order. The diffusion sheet 5, the lower lens sheet 6, and the upper lens sheet 7 function as directivity control elements that control the directivity of light emitted from the light guide plate 2.

The light emitted from the light guide plate 2 is diffused by the diffusion sheet 5 and then condensed by the lower lens sheet 6 and the upper lens sheet 7. For example, one of the lower lens sheet 6 and the upper lens sheet 7 is focused in the vertical direction, and the other is focused in the horizontal direction.

[0110] The upper lens sheet 7 further functions as a reflective polarizing plate. That is, only a specific polarization component (specifically, P wave) of the light from the lower lens sheet 6 is transmitted, and other polarization components are transmitted. Reflects the component (specifically, S wave). The upper lens sheet 7 functioning as a reflective polarizing plate is disposed so that its transmission axis coincides with the transmission axis of the polarizing plate 40c on the back side of the liquid crystal display panel 20.

[0111] When the upper lens sheet 7 functioning as a reflective polarizing plate is not provided, the S wave of the light from the lower lens sheet 6 is absorbed by the polarizing plate 40c as shown on the left side of FIG. It is not used for display.

[0112] On the other hand, when the upper lens sheet 7 functioning as a reflective polarizing plate is provided, as shown on the right side of FIG. Reflected by port 7. The reflected S wave passes through the lower lens sheet 6, the diffusion sheet 5, and the light guide plate 2, is reflected by the reflection sheet 4, and travels toward the upper lens sheet 7 again. In this process, a part of the S wave is converted into a P wave and is incident on the liquid crystal display panel 20 without being reflected by the upper lens sheet 7 or absorbed by the polarizing plate 4 Oc. As a result, the light utilization efficiency is increased and the luminance is improved. As the upper lens sheet 7 functioning as a reflective polarizing plate, for example, BEF-RP manufactured by Sumitomo 3EM Co., Ltd. can be used.

[0113] (Embodiment 6)

FIG. 20 shows a liquid crystal display device 600 according to this embodiment. The liquid crystal display device 600 in the present embodiment includes a further light diffusing element 30 ′ disposed between the light diffusing element 30 and the first polarizing plate 40a, and thus the liquid crystal display device 500 in the fifth embodiment. Is different. Below, the light diffusing element 30 located on the liquid crystal display panel 20 side of the two light diffusing elements 30 and 30 ′ is referred to as the “first light diffusing element” and is observed more than the first light diffusing element 30. The light diffusing element 30 ′ located on the user side is referred to as a “second light diffusing element”.

[0114] The first light diffusing element 30 is disposed immediately above the substrate 22 on the viewer side of the liquid crystal display panel 20, and the second light diffusing element 30 'is composed of the phase difference compensating element 50a and the first difference element. It is arranged between the polarizing plate 40a.

[0115] As described above, in the liquid crystal display device 600 of the present embodiment, a plurality of light diffusion elements.

30, 30 'are arranged separately. By adopting such a configuration, various advantages can be obtained as compared with a configuration in which a single light diffusing element 30 is provided. The advantages obtained will be explained in detail below. [0116] First, the display brightness can be improved. When a single light diffusing element 30 is provided, a part of the light incident on the light diffusing element 30 after passing through the liquid crystal display panel 20 is reflected to the liquid crystal display panel side by back scattering and used for display. Absent. On the other hand, when a plurality of light diffusing elements 30 and 30 ′ are provided, the light back-scattered by the second light diffusing element 30 ′ is reflected again by the first light diffusing element 30 to the viewer side. Can be used for display, so that the brightness of the display is improved.

[0117] Table 3 below shows the results of verifying the brightness improvement effect. When a plurality of light diffusing elements 30, 30 ′ are provided, the haze value of each light diffusing element may be lower than when a single light diffusing element 30 is provided. For example, when light is diffused to the same extent as the light diffusing element 30 having a haze value of 92%, the haze values of the first light diffusing element 30 and the second light diffusing element 30 ′ are set to 60% and 80%, respectively. That's fine. In this case, as shown in Table 3, the brightness was improved by about 30%.

[0118] [Table 3]

[0119] Further, as in this embodiment, a plurality of light diffusing elements 30, 30 'are arranged so as to sandwich the phase difference compensating element 50a, thereby improving color reproducibility (NTSC ratio) and contrast ratio. be able to.

[0120] When a single light diffusing element 30 is provided, it is necessary to set the haze value higher than when a plurality of light diffusing elements 30, 30 'are provided. Therefore, as shown in FIG. 21 (a), after being diffused by the light diffusing element 30, the light does not enter the phase difference compensation element 50a and there is light that is not optically compensated. As a result, the NTSC ratio and contrast ratio are lowered, and the range in which the viewing angle can be suitably enlarged is also narrowed. In addition, since the backscattering in the light diffusing element 30 is strong, the luminance is greatly reduced.

[0121] On the other hand, when a plurality of light diffusing elements 30, 30 'are provided, The haze value may be low. For this reason, as shown in FIG. 21 (b), the amount of light that is not diffused by the first light diffusing element 30 and does not enter the phase difference compensating element 50a is small, and the light that is not optically compensated is small. As a result, there is a wide range in which the viewing angle can be suitably expanded with little reduction in the NTSC ratio and contrast ratio. In addition, since the backscattering in the first light diffusing element 30 is weak, the decrease in luminance is small.

[0122] Table 4 shows the results of verifying the effects of improving the NTSC ratio and contrast ratio. Table 4 shows the display in color STN mode. 1. The measurement results are shown when using an 8-inch panel and driving at 1Z160 duty. As shown in Table 4, the configuration in which the first light diffusing element 30 and the second light diffusing element 30 ′ are provided has an NTSC ratio and a contrast ratio that are different from the configuration in which the single light diffusing element 30 is provided. Has improved. Also, brightness and viewing angle characteristics are improved.

[0123] [Table 4]

[0124] The haze value of the first light diffusing element 30 located on the liquid crystal display panel 20 side may be set higher than the haze value of the second light diffusing element 30 'located on the observer side. Or, conversely, it may be set low.

[0125] When the haze value of the first light diffusing element 30 is set lower than the haze value of the second light diffusing element 30 ', the degree of diffusion by the first light diffusing element 30 on the liquid crystal display panel 20 side is small. Therefore, the effect described with reference to FIG. 21 (b) can be easily obtained. In other words, as shown in Table 4, the effect of improving the NTSC ratio, contrast ratio, brightness, and viewing angle characteristics is high. [0126] Conversely, if the haze value of the second light diffusing element 30 'is set lower than the haze value of the first light diffusing element 30, the diffusion of light by the second light diffusing element 30' on the viewer side will be reduced. Since the degree is small, as shown in Table 4, it is easy to achieve a clear display with little outline blur.

It should be noted that the first light diffusing element 30 in the present embodiment is preferably provided immediately above the substrate 22, similarly to the light diffusing element 30 in the fourth embodiment. When such a configuration is adopted, the distance between the pixel of the liquid crystal display panel 20 and the first light diffusing element 30 is increased by the absence of other members between the first light diffusing element 30 and the substrate 22. Since it can be shortened, it is possible to prevent blurring of the display in which light from different pixels are mixed and mixed.

[0128] The first light diffusing element 30 'preferably serves also as an adhesive layer for bonding the phase difference compensating element 50a and the liquid crystal display panel 20 to the polarizing plate 40a. It is also preferable to serve as an adhesive layer that adheres the phase compensation element 50a. That is, the adhesive layer formed on the surface of the phase difference compensation element 50a (the surface opposite to the observer side) functions as the first light diffusing element 30, and the surface of the polarizing plate 40a (opposite to the observer side). It is preferable that the adhesive layer formed on the side surface) function as the second light diffusing element 30 ′. By adopting such a configuration, the thickness can be further reduced, and the number of manufacturing processes can be reduced.

[0129] When the light diffusing elements 30, 30 'functioning as an adhesive layer are disposed between the substrate 22 and the phase difference compensating element 50a and between the phase difference compensating element 50a and the polarizing plate 40a, the light diffusing element 30 and 30 'function as a buffer layer that absorbs differences in the expansion and contraction of the polarizing plate 40a, retardation compensation element 50a, and substrate 22 due to temperature and humidity, so panel warping and partial color due to temperature and humidity Unevenness can be prevented. Furthermore, since a diffusion material is included in the adhesive, the shear stress can be relieved by sliding the diffusion material in the adhesive. Compared to the case where a single adhesive (that is, a simple adhesive layer) is provided. High function as a buffer layer.

[0130] In addition, the configuration provided with a plurality of light diffusing elements 30, 30 'is superior in optical uniformity and mechanical reliability to the configuration provided with a single light diffusing element 30. .

[0131] When the single light diffusing element 30 is provided, the haze value must inevitably be set high. Therefore, in the internal scattering type diffusion film 30B as shown in FIG. It is necessary to increase the ratio of the particles (diffusion material) 34 inside. For this reason, the dispersibility of the particles 34 (the degree to which the particles 34 are uniformly present in the matrix and the degree to which they are! /) Is lowered, and the optical uniformity is lowered.

[0132] On the other hand, when a plurality of light diffusing elements 30, 30 'are provided, the haze value of each light diffusing element can be set low, so that the dispersibility of the particles 34 can be increased, It is possible to prevent a decrease in optical uniformity.

[0133] Further, when the single light diffusing element 30 is provided, it is necessary to increase the ratio of the particles (diffusing material) 34 in the matrix 33 as described above. When the matrix 33 is formed with an adhesive to function as an adhesive, the adhesive strength decreases.

[0134] On the other hand, when a plurality of light diffusing elements 30, 30 'are provided, the ratio of the diffusing material 34 in each light diffusing element may be low, so the ratio of the adhesive 33 is kept high. Is possible. Therefore, the adhesive force can be increased and the mechanical reliability can be improved.

In this embodiment, the phase difference compensation element 50a is arranged between the first light diffusing element 30 and the second light diffusing element 30 ′. The layer disposed between the second light diffusing element 30 'is not limited to this. The same effect can be obtained by arranging the first light diffusing element 30 and the second light diffusing element 30 ′ separately via a transparent resin layer.

[0136] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. The present invention is preferably used for a display mode having a low viewing angle characteristic, and is preferably used for, for example, an STN mode, a TN mode, and an ECB mode. The present invention is particularly suitable for the STN mode for the following reasons.

[0137] Because the twist angle of the liquid crystal layer is smaller in the TN mode than in the STN mode, the light diffusion element (especially a diffusion film using internal scattering) is affected by back scattering, and a light diffusion element is provided immediately. The reduction in contrast ratio due to is remarkable. In contrast, in the STN mode, the contrast ratio, which is difficult to be affected by backscattering by the light diffusing element, is difficult to decrease. Table 5 below shows the original contrast ratio and the diffusion filter as a light diffusing element for the STN mode passive matrix liquid crystal display device and the TN mode active matrix liquid crystal display device. The contrast ratio after providing the lum is shown.

[0138] [Table 5]

[0139] As can be seen from Table 5, the attenuation factor is 90% in TN mode, whereas the attenuation factor is 25% in STN mode, and the decrease in contrast ratio is smaller in STN mode. Is sure f * i¾.

[0140] Thus, the present invention is more preferably used in the STN mode than in the TN mode. Further, the STN mode is suitably used for the color display STN mode. This is because when the color filter is provided, it is absorbed by the light color filter backscattered by the light diffusing element, and the decrease in contrast ratio is further reduced. Therefore, the present invention is more suitable for the STN mode than the ECB mode that does not provide a color filter and performs color display by changing the birefringence due to an electric field.

Industrial applicability

[0141] According to the present invention, it is possible to suppress glare of a display surface in a liquid crystal display device including a light diffusing element on the front surface of a liquid crystal display panel. Therefore, according to the present invention, a liquid crystal display device having a wide viewing angle characteristic and capable of high-quality display with a high contrast ratio is provided.

[0142] The present invention is suitably used for all transmissive liquid crystal display devices equipped with a knock light, and in particular, a liquid crystal display in a display mode with a low viewing angle characteristic (eg, STN mode, TN mode, ECB mode). It is suitably used for an apparatus.

[0143] In a display mode using birefringence such as the STN mode, the display is adversely affected by light incident obliquely on the liquid crystal layer. Therefore, highly directional light is incident on the liquid crystal layer to It is significant to use the present invention in which it is preferable to use a viewing angle expansion technique in which light modulated by a layer is diffused by a light diffusing element.

Claims

The scope of the claims

[1] a lighting element;

A liquid crystal display panel for modulating light emitted from the illumination element;

A light diffusing element that is disposed on the viewer side of the liquid crystal display panel and diffuses light that has passed through the liquid crystal display panel;

A liquid crystal display device comprising: a first polarizing element having a transmission axis parallel to a first direction and disposed closer to an observer than the light diffusing element.

[2] The apparatus further comprises a second polarizing element having a transmission axis parallel to the second direction and disposed between the liquid crystal display panel and the light diffusing element,

2. The liquid crystal display device according to claim 1, wherein the first direction and the second direction are substantially parallel.

[3] The liquid crystal display device according to [2], wherein an angle formed by the first direction and the second direction is 5 ° or less.

4. The liquid crystal display device according to claim 2, wherein an angle formed by the first direction and the second direction is 2 ° or less.

5. The liquid crystal display device according to claim 1, further comprising an antireflection film disposed between the liquid crystal display panel and the light diffusing element.

6. The liquid crystal display device according to claim 5, wherein the antireflection film includes a plurality of layers having different refractive indexes.

[7] A first 1Z4 wavelength plate disposed between the first polarizing element and the light diffusing element; and a second 1Z4 wavelength disposed between the light diffusing element and the liquid crystal display panel. A liquid crystal display device according to claim 1, further comprising: a plate.

8. The liquid crystal display device according to claim 7, wherein the slow axis of the first 1Z4 wave plate and the slow axis of the second 1Z4 wave plate are substantially orthogonal to each other.

9. The liquid crystal display device according to claim 8, wherein a slow axis of the first 1Z4 wavelength plate forms an angle of approximately 45 ° with the first direction.

[10] The liquid crystal display device according to any one of [1] to [9], further comprising a third polarizing element disposed on a side opposite to an observer side of the liquid crystal display panel.

[11] A phase difference compensating element disposed between the liquid crystal display panel and the third polarizing element is further provided, and a phase difference compensating element is disposed between the liquid crystal display panel and the light diffusing element. The liquid crystal display device according to claim 10, comprising:

[12] A phase difference compensating element disposed between the first polarizing element and the liquid crystal display panel;

An adhesive layer formed on a surface opposite to the observer side of the phase difference compensation element,

The liquid crystal display device according to claim 1, wherein the adhesive layer functions as the light diffusing element.

13. The liquid crystal display device according to any one of claims 1 to 10, further comprising a further light diffusing element disposed between the light diffusing element and the first polarizing element.

14. The liquid crystal display device according to claim 13, further comprising a transparent resin layer disposed between the light diffusing element and the further light diffusing element.

15. The liquid crystal display device according to claim 14, wherein the transparent resin layer is a retardation compensation element.

[16] A first adhesive layer formed on a surface opposite to the observer side of the retardation compensation element, and a first adhesive layer formed on a surface opposite to the observer side of the first polarizing element. 2 additional adhesive layers,

16. The liquid crystal display device according to claim 15, wherein the first adhesive layer functions as the light diffusing element, and the second adhesive layer functions as the further light diffusing element.

[17] The liquid crystal display panel includes a pair of substrates,

17. The liquid crystal display device according to claim 1, wherein the light diffusing element is provided immediately above an observer-side substrate of the pair of substrates.

18. The liquid crystal display device according to claim 1, wherein the light diffusing element includes a lens sheet having a plurality of lenses or a prism sheet having a plurality of prisms.

[19] The light diffusing element includes a diffusion film having a matrix formed of a resin material and particles having a refractive index dispersed in the matrix and different from the refractive index of the matrix. A liquid crystal display device according to any one of the above.

[20] a lighting element;

A liquid crystal display panel for modulating light emitted from the illumination element; A first light diffusing element that is disposed on the viewer side of the liquid crystal display panel and diffuses the light that has passed through the liquid crystal display panel.

A polarizing element disposed closer to the viewer than the first light diffusing element;

A liquid crystal display device further comprising: a second light diffusing element disposed between the first light diffusing element and the polarizing element.

21. The liquid crystal display device according to claim 20, further comprising a transparent resin layer disposed between the first light diffusing element and the second light diffusing element.

22. The liquid crystal display device according to claim 21, wherein the transparent resin layer is a retardation compensation element.

[23] A first adhesive layer formed on the surface of the retardation compensation element opposite to the observer side, and a second adhesive layer formed on the surface of the polarizing element opposite to the observer side And even more layers

The liquid crystal display device according to claim 22, wherein the first adhesive layer functions as the first light diffusing element, and the second adhesive layer functions as the second light diffusing element.

[24] The liquid crystal display panel includes a pair of substrates,

24. The liquid crystal display device according to claim 20, wherein the first light diffusing element is provided immediately above a viewer-side substrate of the pair of substrates.

[25] The illumination element has a light distribution in such a manner that luminance power in a direction forming an angle of 30 ° or more with respect to a normal direction of the display surface is 13% or less of luminance in the normal direction of the display surface The liquid crystal display device according to any one of 1 to 24.

[26] The illumination element has a light distribution such that brightness in a direction forming an angle of 30 ° or more with respect to a display surface normal direction is 3% or less of luminance in the display surface normal direction. Item 25. The liquid crystal display device according to any one of items 1 to 24.