CN102460286A

CN102460286A - Transmission type liquid crystal display device

Info

Publication number: CN102460286A
Application number: CN201080025580XA
Authority: CN
Inventors: 小池康博; 多加谷明广
Original assignee: Japan Science and Technology Agency
Current assignee: Japan Science and Technology Agency
Priority date: 2009-06-09
Filing date: 2010-05-31
Publication date: 2012-05-16
Anticipated expiration: 2030-05-31
Also published as: WO2010143552A1; TWI425275B; KR101375400B1; CN102460286B; TW201116893A; KR20120026601A; JPWO2010143552A1; JP5323190B2

Abstract

Disclosed is a transmission type liquid crystal display which comprises at least a backlight light source, a light control means for controlling the directivity of the light emitted from the backlight light source, a transmissive liquid crystal cell, and a light diffusion layer that contains a light-transmitting polymer, a scatterer and a coloring agent. The transmissive liquid crystal cell and the light diffusion layer are sequentially arranged in such a manner that the transmissive liquid crystal cell is closer to the light control means.

Description

Transmissive liquid crystal display device

Technical field

The present invention relates to a kind of transmissive liquid crystal display device.

Background technology

Transmissive liquid crystal display device is widely used as representational flat-panel monitor because of slim, light weight, advantage of low power consumption.Particularly, popularize significantly as monitor, vehicle mounted display screen, the mobile phone of televisor, PC.Liquid crystal is from as non-luminous device, thereby according to the radiation modality from the light of light source, roughly is divided into these 3 kinds of transmission-types, Transflective, reflection-type.Outside under the situation of the more weak grade of light, through can be stably realizing high image quality from the optical transmission type mode of the suitable intensity of backlight (backlight) irradiation.Therefore, requiring in the purposes of high image quality, mainly use transmissive liquid crystal display device like monitor of televisor, PC etc.

About the molecules align of liquid crystal, TN pattern, VA pattern, IPS pattern, ocb mode etc. are arranged.These patterns have the field angle dependence of the optical characteristics that results from separately.Therefore, even the normal direction (frontal) that is designed at liquid crystal panel has image quality such as good contrast and color, also can reduce in the vergence direction image quality.In order to address this problem, the method for use field angle compensate film shown in figure 10 and the method for use light diffusion layer shown in figure 11 have been proposed.

Use in the method for field angle compensate film, for example shown in figure 10,1 that send from back light, to wide-angle disperse backlight see through diffuser plate 2 after, pass through from the liquid crystal panel 4 that possesses field angle compensate film 3.

Use in the method for field angle compensate film and since used light to wide-angle disperse backlight, so a part of light is sideling through the liquid crystal layer in the liquid crystal panel.Therefore, for to compensating, use field angle compensate film 3 at light and the phase differential of oblique light through liquid crystal layer of normal direction through liquid crystal layer.Commercially available liquid crystal indicator has used the field angle compensate film mostly now.

In addition, the situation that has been to use 2 field angle compensate films that provides among Figure 10, but only use 1 or use 3 above field angle compensate films sometimes.And transparent protective film has the function of field angle compensate film concurrently sometimes.

This field angle compensate film is owing to the birefringence control that need carry out height, so more expensive than other bloomings usually.In addition, above-mentionedly generally depend on wavelength along light and the phase differential of oblique light through liquid crystal layer of normal direction through liquid crystal layer.Therefore; Need adjust so that it has the birefringent wavelength dispersibility that is suitable for used liquid crystal layer the field angle compensate film; But because birefringent wavelength dispersibility is the intrinsic character of material, so and the field angle compensate film that is not easy to obtain to have ideal behavior.

On the other hand, use in the method for light diffusion layer, for example shown in figure 11, send and pass through display panels through liquid crystal panel 4, light diffusion layer 5 successively from back light 1 through the wide body upper edge normal direction of LGP 6.

In the method for using light diffusion layer; Because the most light in combination backlight back with high directivity passes through the liquid crystal layer in the liquid crystal panel generally along normal direction; So also can not be provided for compensating the field angle compensate film of the phase differential of light; And, owing to disperse to wide-angle under the effect of light diffusion layer 5 through the light behind the liquid crystal layer, so can realize broad field angle.

In addition,, for example proposed between Polarizer and glass substrate, to be paved with transparent particulate, and utilized the gap of transparent packing material landfill particulate and the light diffusion layer (for example, referring to patent documentation 1) that obtains for light diffusion layer.

And, proposed to use in transparent resin, be dispersed with the optical diffusion film of scatterer as the method for the diaphragm of Polarizer (for example, referring to patent documentation 2.)。In this patent documentation 2,, put down in writing the scatterer of flat as the scatterer that is dispersed in the transparent resin.

But, use the method for light diffusion layer to exist outer photoconduction to cause the problem that contrast reduces, be used hardly.

In addition, also proposed to share the method (for example, referring to patent documentation 3) of field angle compensate film and light diffusion layer.In this patent documentation 3; Put down in writing and share field angle compensating plate and the light diffusion layer that mainly constitutes by liquid crystal compounds; Improve the method for the field angle of ocb mode, and share and have optically anisotropic cellulose acetate membrane and light diffusion layer, improve the method for the field angle of VA pattern.

But the problems referred to above in the light diffusion layer still are not resolved.

The prior art document

Patent documentation

Patent documentation 1: No. 3517975 instructions of Jap.P.

Patent documentation 1: No. 3822102 instructions of Jap.P.

Patent documentation 2: No. 4054670 instructions of Jap.P.

Summary of the invention

The present invention makes in view of above-mentioned in the past situation, and purpose provides a kind of transmissive liquid crystal display device that when realizing broad field angle, has suppressed outer photogenic contrast reduction.

The invention of claim 1 is a kind of transmissive liquid crystal display device, and it has at least:

Back light;

Light control unit is used to control the direction of light property of sending from above-mentioned back light;

The transmission-type liquid crystal box; With

Light diffusion layer, it contains light transmission polymkeric substance, scatterer and colorant,

Above-mentioned transmission-type liquid crystal box and above-mentioned light diffusion layer dispose in the side near above-mentioned light control unit successively.

The invention of claim 2 is the described transmissive liquid crystal display device of claim 1, and wherein, the inside absorbance of above-mentioned light diffusion layer under the main wavelength of the light that sends from above-mentioned back light is more than 0.014.

The invention of claim 3 is claim 1 or 2 described transmissive liquid crystal display devices, and wherein, the inside absorbance of above-mentioned light diffusion layer under the main wavelength of the light that sends from above-mentioned back light is more than 0.020.

The invention of claim 4 is each described transmissive liquid crystal display device in the claim 1～3, and wherein, the inside absorbance of above-mentioned light diffusion layer under the main wavelength of the light that sends from above-mentioned back light is 0.028～0.062.

The invention of claim 5 is each described transmissive liquid crystal display device in the claim 1～4, wherein, the above-mentioned scatterer in the above-mentioned light diffusion layer to contain concentration high in the above-mentioned liquid crystal cell side of above-mentioned light diffusion layer film thickness direction.

The invention of claim 6 is each described transmissive liquid crystal display device in the claim 1～5; Wherein, above-mentioned light diffusion layer is in above-mentioned light transmission polymkeric substance, to disperse above-mentioned light-scattering material and scattering layer that forms and the lamilated body that contains the dyed layer of above-mentioned light transmission polymkeric substance and above-mentioned colorant.

According to the present invention, can be provided at and suppress the transmissive liquid crystal display device that outer photogenic contrast reduces when realizing broad field angle.

Description of drawings

Fig. 1 is the cross-sectional of the light diffusion layer of first embodiment.

Fig. 2 explains the effect of the light diffusion layer that the present invention relates to and the figure of function.

Fig. 3 is the cross-sectional of the light diffusion layer of second embodiment.

Fig. 4 is the cross-sectional of the light diffusion layer of the 3rd embodiment.

Fig. 5 is the cross-sectional of the light diffusion layer of the 4th embodiment.

Fig. 6 is the cross-sectional of the light diffusion layer of other embodiments.

Fig. 7 is the cross-sectional of one of the structure in the expression transmissive liquid crystal display device of the present invention example.

Fig. 8 is the inside absorbance spectrum of the sample 11～14 among the embodiment 1.

Fig. 9 is the internal transmission rate spectrum of the sample 11～14 among the embodiment 1.

Figure 10 is the figure that passes through the path that light in the LCD that has used existing field angle compensate film is described.

Figure 11 is the figure that passes through the path that light in the LCD that has used general light diffusion layer is described.

Figure 12 is the photo of expression influence of outer light when utilizing existing light diffusion layer, (A) is the photo that does not have the state of outer light to take down, (B) is the photo of shooting under the state of light having outside.

Embodiment

Transmissive liquid crystal display device of the present invention has at least: back light; Light control unit is used to control the direction of light property of sending from above-mentioned back light; The permeation type liquid crystal box; With the light diffusion layer that contains light transmission polymkeric substance, scatterer and colorant, wherein above-mentioned permeation type liquid crystal box and above-mentioned light diffusion layer are disposing near the near side of above-mentioned light control unit successively.

Usually the color offset that produces for the field angle that reduces because of LCD can use field angle compensate film shown in figure 10.Need give this field angle compensate film suitable birefringent wavelength dispersion.But birefringent wavelength dispersion is the intrinsic characteristic of material, the polymkeric substance that is not easy to obtain to have desirable wavelength dispersibility.

Therefore, adopt to use among the present invention light diffusion layer shown in Figure 11 method, be about to the method that the higher backlight and light diffusion layer of directivity share.Through adopting this method; Reduced because of light with respect to the normal direction (0 °) of liquid crystal panel with the color offset of bigger angle through the field angle that produces etc.; Removed and used the existing problem of method of field angle compensate film, and can realize broad field angle.

Light diffusion layer of the present invention is owing to contain scatterer, so that have diffusion backlight than highly directive, realize broad field angle.And; Light diffusion layer of the present invention is owing to contain colorant such as pigment; So have the function of the outer light that absorbs institute's incident; Through with this light diffusion layer as being attached to than above-mentioned liquid crystal cell away from an above-mentioned side backlight, particularly for example for (transparent) protective seam of observer's side, maybe give the outside at this protective clear layer with this light diffusion layer, can suppress the reduction of contrast.

Here, for function of the present invention and effect are described, at first the actual conditions of the LCD of existing light diffusion layer have been used in explanation.

Figure 12 takes and the photo that obtains the LCD that is provided with the PMMA polymer film (light diffusion layer) that is added with alumina particulate up front (right half side) and LCD (left side is half side) that this film is not set.

Here; Figure 12 (A) is darkening the room, is taking under the state of outer illumination less than LCD; On the other hand, Figure 12 (B) is at the fluorescent light of opening the ceiling portion that is positioned at the room, and the illumination of fluorescent light is photographed under the state on the LCD.

Relatively Figure 12 (A) with can know that (B) light time outside the irradiation whitens after on LCD, light diffusion layer being set, contrast reduction (right side of Figure 12 (B)).Compare with the situation of Figure 12 that does not shine outer light (A), generation is whitened and is made the reason of contrast reduction be in Figure 12 that has shone outer light (B), and after outer light got into light diffusion layer generation scattering, this light is the outside of back light diffusion layer (observer's side) once more.

Used the LCD of existing light diffusion layer to have the problem that gets into the contrast reduction that produces because of outer light.

Under above-mentioned condition; The inventor recognizes; Be utilized in and be added with the light diffusion layer that the scatterer that is used to make the light diffusion obtains with being used for colorant such as light absorbing pigment in the light transmission polymkeric substance; Can outside the fineness of roughly keeping image, inhibition in the photogenic whiting, will disperse to wide-angle from the light of backlight.First embodiment as such light diffusion layer is as shown in Figure 1.

Among Fig. 1, in light diffusion layer 10, scatterer 12 is dispersed in the light transmission polymkeric substance 14, and more preferably scatterer 12 is evenly distributed on the situation in the light transmission polymkeric substance 14.And light transmission polymkeric substance 14 contains colorants (not shown) such as pigment.

, contain colorant here through making light diffusion layer 10, can weaken cause whitening outer light produced returns light, its reason is inferred as follows.But the present invention does not receive the qualification of such supposition.

Shown in the solid arrow of Fig. 2, from about the only roughly scattering 1 time that arrives observer's eyes in the light of backlight～for several times and the light through light diffusion layer 10.Relative therewith, arrive in the outer light only getting into of observer's eyes be scattered behind the light diffusion layer 10 material 12 repeatedly scattering more times and arrive the light of observer's side.Therefore, the outer light ratio distance (referring to the dotted arrow of Fig. 2) of in light diffusion layer 10, advancing from the light of backlight.

Here, when making light diffusion layer 10 contain colorant, the long outer light of travel distance is absorbed by colorant gradually, and the light that returns that outer light produced that causes whitening is weakened.

So long as in view of above-mentioned ultimate principle, the formation of light diffusion layer is not limited to formation shown in Figure 1.Second embodiment as light diffusion layer provides Fig. 3.

Among Fig. 3, scatterer 12 is respectively in the side of light diffusion layer 10 thickness directions near liquid crystal layer.Both can arrange between the scatterer 12, also can contact with appropriate intervals, can also irregular alignment.

In addition, the 3rd embodiment as light diffusion layer provides Fig. 4.

Among Fig. 4, scatterer 12 is arranged at the thickness direction of light diffusion layer and is formed multilayer.Scatterer 12 also can formation rule stratiform.

And then, provide Fig. 5 as the 4th embodiment of light diffusion layer.

Among Fig. 5, be provided with the dyed layer 18 that comprises light transmission polymkeric substance 14 and colorant in the outside (observer's side) of the scattering layer 16 that comprises light transmission polymkeric substance 14 and scatterer 12.Scattering layer 16 can not contain colorant, but also can contain colorant.

Can know that by shown in Figure 2, backlight and outer light travel path separately the light diffusion layer of the formation through forming Fig. 3, Fig. 4 and Fig. 5 makes the outer light that is observed as the returning light longer distance of in light diffusion layer, advancing, thereby outer light is weakened.Particularly the light diffusion layer of the formation of Fig. 5 can effectively weaken outer light.

In addition, scattering layer 16 shown in Figure 5 also can distribute near a side at film thickness direction like Fig. 3 and scatterer shown in Figure 4 12.

Also can use technique known to implement antireflection or non-glare treated in the outside of light diffusion layer 10.And, also can as shown in Figure 6ly in light diffusion layer 10, introduce anti-dazzle with particle 20.

Below, the composition that constitutes light diffusion layer is described.

The preferred various organic pigments of colorant, but, also can use organic pigment, inorganic pigment so long as to be refine to the degree and the disperse state that do not make the remarkable deterioration of image resolution ratio good.Specifically, can use known organic pigment, inorganic pigments such as carbon black, anthraquinone based compound 、 perylene based compound, double compound nitrogen series, phthalocyanine based compound, isoindoline based compound 、 dioxazine based compound.Do not limit the kind of organic pigment is special.

Colorant can use a kind of colorant separately, also can make up and use multiple colorant.The spectrum of the inside absorbance of using a kind of or combination to use multiple light absorber and obtaining is roughly the same value in the whole wavelength coverage of visible light (about 380nm～about 750nm) preferably under desirable state.

As the backlight liquid crystal display light source, use cold-cathode tube or LED mostly, usually at 3 peaks that main wavelength has light intensity that are equivalent to red (R), green (G), blue (B).Therefore, the light absorption of the pigment that adds in the present invention can be identical absorbance (transmissivity) in the whole wavelength coverage of visible light not necessarily as stated, can be the light absorption after suitable absorbance balance has been put in order in 3 main wavelength downward modulations backlight.

Consider that from the viewpoint that shows good white the difference that preferably is adjusted into each inner absorbance of light diffusion layer under the main wavelength of the light that sends from back light is as far as possible little.For example, be under the situation of cold-cathode tube as light source of 3 wave length types using main wavelength, the difference that preferably is adjusted between each inner absorbance of light diffusion layer under the wavelength of about 435nm, about 545nm and about 615nm is as far as possible little.

Specifically, the difference of each inner absorbance of light diffusion layer is preferably below 0.05 under the main wavelength of the light that sends from back light, more preferably below 0.02, further is preferably below 0.01.

Here, the main wavelength of the so-called light that sends from back light for example is meant 3 wavelength of about 435nm, about 545nm, about 615nm for general cold-cathode tube.In addition, main wavelength is that 3 wavelength light source in addition also is used as backlight sometimes.For example, also exist in and add on the basis of bluish-green red these 3 wavelength that 4 dark red wavelength are backlight etc., therefore, be main wavelength with these 4 wavelength set this moment.In addition, under the situation of LED, have sometimes and the above-mentioned general different main wavelength of cold-cathode tube.

In addition, big skew does not take place in the main wavelength of the light that sends from back light yet after the light control unit that is used to control its directivity passes through, can be according to the inside absorbance of adjusting light diffusion layer through the main wavelength of the light behind the light control unit.

In addition, the resin that is arranged in color filter and each layer on the liquid crystal cell causes the light of specific wavelength to weaken or peak wavelength shift sometimes.At this moment, also can consider to be about to inject the spectrum of the light of light diffusion layer, and according to the inside absorbance of the main wavelength adjustment light diffusion layer of the light that is about to inject light diffusion layer.

In table 1, provided according to the main wavelength of general cold-cathode tube and adjusted inside absorbance and transmissivity in one of inner absorbance, the light scattering layer of the present invention example.

[table 1]

As shown in table 1, the primary waves progress row adjustment of the preferred light of considering to send from the back light as light source makes the difference of each inner absorbance of the light diffusion layer under this main wavelength diminish.

On the other hand, from improving the viewpoint of brightness, preferably the light from backlight is not absorbed by the colorant in the light diffusion layer 10 as far as possible, thereby arrives the observer after seeing through light diffusion layer.Therefore, preferably adjust the content of the colorant in the light diffusion layer 10, can suppress absorbance scope in the light weakening returning of producing by outer light from the loss of the light of backlight to form.

Therefore; Light and inhibition are considered from the object of the invention that weakens of the light of backlight outside weakening; Preferably the inside absorbance of light diffusion layer under the main wavelength of the light that sends from back light is adjusted into more than 0.014, more preferably more than 0.020, further is preferably more than 0.028.If further consider front face brightness; Then preferably the inside absorbance of light diffusion layer under the main wavelength of the light that sends from back light is adjusted into 0.014～0.095 scope; 0.014～0.088 scope more preferably; Further be preferably 0.020～0.088 scope, further be preferably 0.028～0.088 scope, further be preferably 0.028～0.062 scope again.

To light transmission polymkeric substance in the light diffusion layer 14 and scatterer 12 preferred suitable selections so that the size of the combination of refractive index separately and scatterer 12 is suitable value.Through these adjustment, be scattered material 12 scatterings and realize Wide-angle from the light of backlight, and efficient presents high brightness through light diffusion layer well.And then, through these adjustment, can suppress because of setting up image blurring that light diffusion layer produces.

Specifically; As the light transmission polymkeric substance 14 that is used for light diffusion layer; Can use the various light transmission polymkeric substance such as cyclic olefin polymer, norbornene-based polymer of acrylate copolymer, the polycarbonate representative of cellulose derivative, the polymethylmethacrylate representative of tri acetyl cellulose representative, but be not limited to these polymkeric substance.And the light transmission polymkeric substance 14 that is used for light diffusion layer both can be homopolymer or multipolymer, also can use mixture of polymers.In addition, these polymkeric substance both can also can contain various additives such as plastifier for containing the highly purified polymkeric substance of other additives hardly.In addition, this light transmission polymkeric substance 14 also can be for having fusible polymkeric substance.

The combination of the refractive index basis of light transmission polymkeric substance 14 and scatterer 12 grades of interpolation suitably selects, thereby can not decide without exception, but generally is preferably 1.33～1.65, and more preferably 1.45～1.60.For example, the refractive index of tri acetyl cellulose is 1.48, and the refractive index of polymethylmethacrylate is 1.49.

As scatterer 12, the particle of preferred light transmission.Specifically can use alumina particle, silicone polymer particles, condensate of melamine and formaldehyde particle, benzoguanamine formaldehyde condensation composition granule, benzoguanamine condensate of melamine and formaldehyde particle, titan oxide particles, silica dioxide granule etc., but be not limited to these particles.

The combination of the mean grain size basis of scatterer 12 and above-mentioned light transmission polymkeric substance 14 grades suitably selects, thereby can not decide without exception, but generally is preferably 0.05 μ m～25 μ m, and more preferably 0.1 μ m～20 μ m further are preferably 0.8 μ m～18 μ m.

Also come suitably to select for the refractive index of scatterer, thereby can not decide without exception, but generally be preferably 1.40～2.75, more preferably 1.43～1.9 according to the combination of above-mentioned light transmission polymkeric substance etc.And the difference of the refractive index of the refractive index of scatterer 12 and light transmission polymkeric substance 14 is preferably 0.02～1.25, more preferably 0.03～0.30.Consider that from the viewpoint of light diffusion effect the refringence of above-mentioned scope is preferred.

Scatterer 12 comes suitably adjustment with respect to the content of light transmission polymkeric substance 14 according to the kind of light transmission polymkeric substance 14, the kind and the size of scatterer 12; Thereby can not decide without exception; But generally be preferably 0.1 quality %～50 quality %, more preferably 0.5 quality %～15 quality %.

As stated, light diffusion layer of the present invention has the function and the light absorbing function of diffusion light.

For light diffusion function; After in the formation of the transmissive liquid crystal display device stated (referring to Fig. 7), angle distribution that can be through relatively injecting the brightness backlight of (before being equivalent to inject the protective clear layer 26 of Fig. 7) before the liquid crystal panel with should be estimated by the angle distribution of the brightness after spreading at light diffusion layer through liquid crystal panel from the light of backlight.

More easily, can estimate through being determined at the mist degree (Haze, mist value) that adds the membranaceous sample that forms behind the scatterer in the light transmission polymkeric substance.

In order to spread to obtain enough field angle at light diffusion layer, generally need the mist degree more than 40% from the stronger light of sidelight (edge light) formula directivity backlight.But required mist degree depends on from the degree of divergence of the light of backlight and the degree of divergence of the light that desire obtains after seeing through light diffusion layer.

For example, if the half value overall with of and brightness angle distribution very strong by directivity is a light backlight below about 30 ° when obtaining the brightness angle distribution of degree of divergence of general liquid crystal TV set, then preferred mist degree is more than 70%, more preferably more than 80%.

In addition; When the half value overall with of using the brightness angle distribution is high directivity backlight below about 30 °; The inside absorbance of light diffusion layer under the main wavelength of the light that sends from back light preferably is adjusted into more than 0.028; More preferably 0.028～0.088 scope further is preferably 0.028～0.062 scope, considers that from the viewpoint that shows good black and keep high front face brightness inner absorbance is that 0.055～0.062 scope is desirable.

On the other hand, if lower backlight of user tropism, even would then utilize the lower light diffusion layer of mist degree also can fully spread.For example, the half value overall with of brightness angle distribution greater than 30 ° and smaller or equal to 50 ° about and have under the situation backlight of moderate directivity, mist degree is preferably more than 60%, more preferably more than 70%.

And; The half value overall with of using the brightness angle distribution greater than 30 ° and smaller or equal to 50 ° about and have under the situation backlight of moderate directivity; The inside absorbance of light diffusion layer under the main wavelength of the light that sends from back light preferably is adjusted into more than 0.020; 0.020～0.095 scope more preferably; Further be preferably 0.020～0.068 scope, consider from the viewpoint that shows good black and keep high front face brightness, inner absorbance is that 0.029～0.068 scope is desirable.

As stated; According to from used direction of light property backlight; Though the haze value that is more suitable for is more or less different with the scope of inner absorbance, consider from the viewpoint of the whiting that suppresses picture, under the situation of the light of arbitrary directivity; As long as the inside absorbance of light diffusion layer is adjusted into more than 0.014 just can brings into play effect, after the embodiment that states also can show this point.

For light absorbing function, can estimate through utilizing commercially available determinator to measure absorbance (or transmissivity).Use in the mensuration and in the light transmission polymkeric substance, added the membranaceous sample that obtains behind the light absorber.Do not add relatively the using of light absorber membranaceous sample establishment of base line through using this moment, deducts the influence of specimen surface reflection.The absorbance that the film that obtains like this is inner is defined as inner absorbance.Obtain attenuation rate and transmissivity by inner absorbance.It is defined as inner attenuation rate (%) and internal transmission rate (%) respectively.Inner attenuation rate and internal transmission rate add up to 100%.

At last, will be arranged on the transmissive liquid crystal display device of formation as shown in Figure 7, estimate its effect based on the light diffusion layer that above-mentioned evaluation result suitably designs.

Method for making as light diffusion layer 10; For example can enumerate such method: preparation contains light transmission polymkeric substance 14 and scatterer 12 and colorant and the coating fluid of the solvent that contains as required etc., utilizes known method that this coating fluid is coated on the outermost layer of protective clear layer 26 liquid crystal cells such as grade.

Describe in the face of transmissive liquid crystal display device down.

Transmissive liquid crystal display device of the present invention has at least: back light; Light control unit is used to control the direction of light property of sending from above-mentioned back light; The transmission-type liquid crystal box; And light diffusion layer, this light diffusion layer contains light transmission polymkeric substance, scatterer and colorant, and above-mentioned transmission-type liquid crystal box and above-mentioned light diffusion layer are successively set on the side near above-mentioned light control unit.

Use Fig. 7 explains one of the concrete formation of transmissive liquid crystal display device of the present invention example.

Among Fig. 7; The light that sends from back light 22 becomes the light with directivity through LGP 24; This light is spread at light diffusion layer 10 through protective clear layer 26, light polarizing film 28, protective clear layer 26, glass substrate 30, liquid crystal layer 32, color filter 34, glass substrate 30, protective clear layer 26, light polarizing film 28, protective clear layer 26.

In the transmissive liquid crystal display device of Fig. 7; As liquid crystal cell of the present invention, provided that layer successively closes protective clear layer 26, light polarizing film 28, protective clear layer 26, glass substrate 30, liquid crystal layer 32, color filter 34, glass substrate 30, protective clear layer 26, light polarizing film 28 and protective clear layer 26 and the liquid crystal cell that obtains.But be not limited to such formation,, can suitably select the use sheet number of each parts etc., and also can set up the parts beyond these parts as long as have liquid crystal layer 32 at least.

For example, also can lump together with light diffusion layer 10 with light diffusion layer 10 adjacent protective clear layers 26, use light diffusion layer as protective seam with what put down in writing among Fig. 7.Protective clear layer 26 and light diffusion layer 10 are being lumped together; Under the situation that makes light diffusion layer double as protective seam and design; Can utilize known film-forming methods such as solution casting system embrane method, extrusion by melting that this light diffusion layer is made film forming; And utilize known method that it is attached on the light polarizing film 28, make thus.

In addition, also can be at adhesive phase (not shown) the interpolation scatterer 12 and the colorant of the protective clear layer 26 in be used for the fitting light polarizing film 28 and the outside, with this adhesive phase as light diffusion layer.In this adhesive phase, comprise binding property polymer, and with this binding property polymer as the light transmission polymkeric substance.

As long as the light diffusion layer 10 that transmissive liquid crystal display device of the present invention possessed contains light transmission polymkeric substance, scatterer and colorant, can for the light diffusion layer of the light diffusion layer of the light diffusion layer of the light diffusion layer of first mode shown in Figure 1, second mode shown in Figure 3, Third Way shown in Figure 4, cubic formula shown in Figure 5 and importing shown in Figure 6 arbitrary light diffusion layer of anti-dazzle light diffusion layer with particle 20.

As back light 22, preferred cold-cathode tube, but be not limited thereto, also can use thermionic-cathode tube, LED etc.For LED, both can use White LED, the LED that also can use red, green, blue with forms white.

And, can use laser instruments such as laser diode as back light.Particularly send the laser instrument of polarized light owing to can obtain high-level efficiency, so be fit to transmissive liquid crystal display device of the present invention.Laser diode is identical with LED, and the light that can mix several colors forms white.

As LGP 24, can be suitable for known LGP.

In addition, in the transmissive liquid crystal display device of Fig. 7, as light source portion back light 22 and LGP 24 have been installed, but also can have further been set up miscellaneous part.For example, can between LGP and liquid crystal panel, dispose usually as backlight with prismatic lens parts, that be used to improve brightness (prism sheet), have prism structure diffuser plate, have the reflection type polarizing film (for example the DBEF of 3M society etc.) of light recirculation function etc.Though omitted record among Fig. 7, can certainly be around LGP with component configuration such as reflector plate, lamp reflectors.

In addition, in the transmissive liquid crystal display device of Fig. 7,, also can control direction of light property through the mode beyond the LGP though form light with directivity through LGP 24.For example; Also can be shown in figure 10; Cold-cathode tube is disposed with proper spacing, place diffuser plate 2 then, configuration has the film of light-focusing function on this diffuser plate 2; Thereby the replacement LGP, or utilize the diffuser plate that diffuser plate self enforcement microfabrication has been possessed light-focusing function to replace LGP.In addition, use replacing cold-cathode tube under the situation of element of the stronger light of sender tropisms such as LED, LD, use after the direction of light property reduction that also can use diffusion sheet or diffuser plate to send from these elements.In addition, light guide member, optically focused parts, light-reflecting components that also can appropriate combination has been applied in lighting use on these elements be adjusted into appropriateness with the angle distribution of brightness.

As transmission-type liquid crystal box (liquid crystal layer) 32, can be suitable for known transmission-type liquid crystal box.And, also can suitably be suitable for known elements for the protective clear layer that is used for transmissive liquid crystal display device of the present invention 26, light polarizing film 28, glass substrate 30, color filter 34.In addition, transmissive liquid crystal display device of the present invention also can use the field angle compensate film with the light diffusion layer that the present invention relates to.

Even used the transmissive liquid crystal display device of the light diffusion layer that the present invention relates to not use the field angle compensate film also can realize broad field angle.And, used the transmissive liquid crystal display device of the light diffusion layer that the present invention relates to can suppress the reduction of contrast.

In light diffusion layer, disperse to obtain sufficient field angle for the light that directivity is stronger, generally need make light diffusion layer contain more scatterer and improve mist degree.The result that light diffusion layer contains more scatterer is, the whiting of outer light shown in figure 12 is remarkable, and existing light diffusion layer is difficult to strong backlight of user tropism freely.

But,,, also can when suppressing whiting, fully realize broad field angle even during stronger backlight of user tropism if use light diffusion layer of the present invention.

Embodiment

Below, illustrate in greater detail the present invention based on embodiment, but the present invention is not limited to these embodiment.

[embodiment 1]

< making of light diffusion layer >

Method with shown in following is made individual layer light diffusion layer shown in Figure 1.

In methylene chloride, add tri acetyl cellulose, make its dissolving, and stir, prepare polymer solution.This solution coat on the stainless steel substrate of surface smoothing, is made solvent evaporates, make the protective clear layer of the about 50 μ m of thickness thus.

On the other hand, in methylene chloride, add polymethylmethacrylate, redness, blueness and yellow organic pigment, add alumina particulate (mean grain size 1.1 μ m) again, stir, prepare dispersion liquid.

In addition, with respect to polymethylmethacrylate to be red, the blue and yellow organic pigment of concentration (quality %) interpolation of below table 2.And, add 10 mass parts alumina particulates with respect to 100 mass parts polymethylmethacrylates.

Suitably the adjustment concentration dichloromethane is coated with so that above-mentioned dispersion liquid can access the light diffusion layer of target thickness and be easy to.This dispersion liquid is coated on the above-mentioned protective clear layer, obtains the light diffusion layer 11～14 of the about 30 μ m of thickness.

< mensuration of inner absorbance, inner attenuation rate and internal transmission rate >

The film (measure and use sample) of the composition behind the alumina particulate is only removed in making from the light diffusion layer of above-mentioned composition, be used to measure inner absorbance, inner attenuation rate and internal transmission rate.

Measure in the making with sample, at first in methylene chloride, add polymethylmethacrylate, redness, blueness and yellow organic pigment, prepare solution after stirring.On the stainless steel substrate of surface smoothing, solvent is volatilized substantially this solution coat, the mensuration that is made into the about 30 μ m of thickness thus is with sample 11～14.In addition, mensuration is equivalent to above-mentioned light diffusion layer 11～14 respectively with sample 11～14.

Use commercially available spectrophotometer, measure inner absorbance, inner attenuation rate and internal transmission rate with the film of sample 11～14 measuring.

The inside absorbance here is meant scatterers such as in the light transmission polymkeric substance, not adding alumina particle but the absorbance of having added the film that forms behind the light absorption material.Its implication is the reflection that does not comprise film surface, the absorbance that is produced by the film light absorption inside.

The inner attenuation rate attenuation rate (%) that inner absorbance converts and obtains of serving as reasons.

In addition, the internal transmission rate is the value that is calculated by following formula.

[internal transmission rate]=100 (%)-[inner attenuation rate]

In addition, make the polymer film from above-mentioned composition, removed the composition behind alumina particulate and the organic pigment.The value of using this film to record as benchmark (baseline), is carried out the mensuration of above-mentioned film, obtain thus deducted after the loss that surface reflection produced, inner absorbance, inner attenuation rate and internal transmission rate.The result lists in table 2.

[table 2]

And, in Fig. 8, provided the inside absorbance spectrum of said determination with sample 11～14, in Fig. 9, provided the internal transmission rate spectrum of said determination with sample 11～14.

< evaluation of mist degree >

For the mist degree (mist value) of estimating light diffusion layer, make the polymer film (mist degree is measured and used sample) that does not add organic pigment and only added the alumina particulate (mean grain size 1.1 μ m) of same concentrations.

Mist degree is measured in the making with sample, at first in methylene chloride, adds polymethylmethacrylate, alumina particulate, prepares dispersion liquid after stirring.With respect to 100 mass parts polymethylmethacrylates, add 10 mass parts alumina particulates.This dispersion liquid is coated on the stainless steel substrate of surface smoothing, solvent is volatilized substantially, the mist degree mensuration that obtains the about 30 μ m of thickness is used sample.

Measure this mist degree with haze meter (Japanese electric look Industrial Co., Ltd, NDH2000) and measure that to use sample, mist degree be about 91%.

< evaluation of picture whiting >

On the transmission-type liquid crystal display element of the formation of Fig. 7, give above-mentioned light diffusion layer 11～14, estimate.Liquid crystal panel uses the VA type, uses the cold-cathode tube of main wavelength for about 435nm, about 545nm and about 615nm as back light.And oblique 45 degree shine with the promptly about 100lx of the illumination that forms general level of activity with fluorescent light from picture the place ahead, estimate the whiting of picture.Picture is a black display during evaluation.

Its result, the sample that inner absorbance is high more, the whiting degree is low more.As long as inner absorbance is 0.014 just can be practical, be 0.028 almost not observe whiting when above, particularly inner absorbance is sample 13 and the sample 14 more than 0.055, shows good black.

Transmission-type liquid crystal display element to the evaluation that is used for above-mentioned picture whiting uses nitometer (TOPCON of Co., Ltd., BM-7FAST), measures front face brightness and brightness angle distribution.Picture is become to be measured after white shows.

The half value overall with of the angle distribution of the brightness backlight of (before being equivalent to inject the protective clear layer 26 of Fig. 7) is about 30 degree before injecting liquid crystal panel.Through liquid crystal panel, light diffusion layer is up front spread from this light backlight, and the result is that the half value overall with all becomes about 70 degree in the arbitrary layer in light diffusion layer 11～14.

In order to compare, the existing liquid crystal panel that possesses the field angle compensate film is also measured front face brightness and brightness angle distribution.This existing liquid crystal panel that possesses the field angle compensate film is commercially available LCD, does not have light diffusion layer, does not also possess the such layer that is added with colorant of the present invention.

Picture for the existing liquid crystal panel that possesses the field angle compensate film; The half value overall with of its brightness angle distribution is about 70 degree; Can confirm, to have the necessary brightness angle of the sufficient field angle of acquisition distributed degrees thus although used the backlight of high directivity according to The above results.

In addition, the brightness angle distribution for vertical direction has also obtained roughly the same characteristic.And then as shown in table 3 for front face brightness, the interpolation concentration of organic pigment is high more, and front face brightness is low more.As long as the inside absorbance under the main wavelength of the light that sends from back light is below 0.062, can obtain and above front face brightness, the brightness angle distributed degrees of the picture equal extent of the available liquid crystal panel that possesses the field angle compensate film.

[table 3]

Can know by above content; Inside absorbance through under the main wavelength that is formed on the light that sends from back light is the light diffusion layer of about scope below 0.062, can access front face brightness and the LCD of brightness angle distributed degrees more than the picture equal extent that has with the available liquid crystal panel that possesses the field angle compensate film shown in Figure 10.Particularly the inside absorbance under the main wavelength of the light that sends from back light is the light diffusion layer of 0.028～0.062 scope, has obtained good characteristic.

Image blurring by due to the light diffusion layer takes place in these LCDs hardly.And, although be the formation of not using the field angle compensate film, also obtained the roughly equal field angle of picture with the available liquid crystal panel that possesses the field angle compensate film shown in Figure 10.

[embodiment 2]

< making of light diffusion layer >

Light diffusion layer 21～24 with the individual layer shown in Figure 4 of the method making shown in following.

At first, likewise operate, prepare protective clear layer with embodiment 1.

On the other hand; In methylene chloride, add polymethylmethacrylate, redness, blueness and the yellow organic pigment identical with embodiment 1; Further add condensate of melamine and formaldehyde particulate (mean grain size 1.3 μ m), prepare dispersion liquid after stirring.

In addition, with respect to polymethylmethacrylate to be red, the blue and yellow organic pigment of concentration (quality %) interpolation of below table 4.And, add 5 mass parts condensate of melamine and formaldehyde particulates with respect to 100 mass parts polymethylmethacrylates.

Suitably the adjustment concentration dichloromethane is coated with so that above-mentioned dispersion liquid can access the light diffusion layer of target thickness and be easy to.This dispersion liquid is coated on the above-mentioned protective clear layer, obtains the light diffusion layer of the about 30 μ m of thickness.

With transmission electron microscope the cross section of gained light diffusion layer is observed, confirmed that thus the light transmission particulate of interpolation (condensate of melamine and formaldehyde particulate) is as shown in Figure 4, in light diffusion layer, exists near a side surface.

The composition behind the condensate of melamine and formaldehyde particulate has only been removed in making from the light diffusion layer of above-mentioned composition film (measuring with sample 21～24) is used to measure inner absorbance, inner attenuation rate and internal transmission rate.Measure method for making with sample 21～24 with reference to the method for making of the mensuration among the embodiment 1 with sample 11～14.Use the inside absorbance of commercially available these films of spectrophotometric determination, inner attenuation rate, internal transmission rate.

In addition, make the polymer film from above-mentioned composition, removed the composition behind condensate of melamine and formaldehyde particulate and the organic pigment.The value of using this film to record as benchmark (baseline), is carried out the mensuration of above-mentioned film, obtain thus deducted after the loss that surface reflection produced, inner absorbance, inner attenuation rate and internal transmission rate.The result lists in table 4.

[table 4]

< evaluation of mist degree >

In order to estimate the mist degree of light diffusion layer, making is not added organic pigment and has only been added the condensate of melamine and formaldehyde particulate (mean grain size 1.3 μ m) of same concentrations, and thickness is the polymer film (mist degree is measured and used sample) of about 30 μ m.This mist degree is measured with the method for making of sample and is measured the method for making with sample with reference to the mist degree among the embodiment 1.

Use haze meter (Japanese electric look Industrial Co., Ltd, NDH2000) that the mist degree of made is measured and measure with sample, mist degree is about 94%.

< evaluation of picture whiting >

On the transmission-type liquid crystal display element of the formation of Fig. 7, give above-mentioned light diffusion layer 21～24, carry out the evaluation of light diffusion layer.Liquid crystal panel uses the VA type, as the cold-cathode tube of the main wavelength of use backlight for about 435nm, about 545nm and about 615nm.And oblique 45 degree shine with the promptly about 100lx of the illumination that forms general level of activity with fluorescent light from picture the place ahead, estimate picture whiting degree.Picture is a black display during evaluation.

Its result, the sample that inner absorbance is high more, the whiting degree is low more.As long as the inside absorbance under the main wavelength of the light that sends from back light is 0.014 just can be practical; Be 0.028 almost not observe whiting when above; Particularly the inside absorbance under the main wavelength of the light that sends from back light is the sample 23 and sample 24 more than 0.055, shows good black.

To the transmission-type liquid crystal display element of the evaluation that is used for above-mentioned picture whiting, use nitometer (TOPCON of Co., Ltd., BM-7FAST) to measure front face brightness and brightness angle distribution.Making picture is to measure after white shows.

The half value overall with of the angle distribution of the brightness backlight of (before being equivalent to inject the protective clear layer 26 of Fig. 7) is about 30 degree before injecting liquid crystal panel.Through liquid crystal panel, light diffusion layer is up front spread from this light backlight, and the result is that the half value overall with all becomes about 70 degree in the arbitrary layer in light scattering layer 21～24.

Picture for the available liquid crystal panel that possesses the field angle compensate film; The half value overall with of its brightness angle distribution is about 70 degree; Can confirm, to have the necessary brightness angle of the sufficient field angle of acquisition distributed degrees thus although used the backlight of high directivity according to The above results.

In addition, the brightness angle distribution for vertical direction has also obtained roughly the same characteristic.And then as shown in table 5 for front face brightness, the interpolation concentration of organic pigment is high more, and front face brightness is low more.As long as the inside absorbance under the main wavelength of the light that sends from back light is below 0.062, can obtain and above front face brightness, the brightness angle distributed degrees of the picture equal extent of the available liquid crystal panel that possesses the field angle compensate film.

[table 5]

[embodiment 3]

Method making layer shown in Figure 5 with shown in following closes light diffusion layer; Promptly close the light diffusion layer of dyed layer 18 at the outside of scattering layer 16 (observer's side) layer; Said scattering layer 16 adds scatterer and forms in the light transmission polymkeric substance, said dyed layer 18 adds colorant and forms in the light transmission polymkeric substance.Select tri acetyl cellulose as the light transmission polymkeric substance.

< making of light diffusion layer >

At first, tri acetyl cellulose is dissolved in the methylene chloride, further adds alumina particulate (mean grain size 1.1 μ m), stir, prepare dispersion liquid-1.Add 10 mass parts alumina particulates with respect to 100 mass parts tri acetyl celluloses.Suitably adjust concentration dichloromethane so that dispersion liquid-1 can obtain target film thickness and be easy to coating.

On the other hand, tri acetyl cellulose and red, blue, yellow organic pigment are dissolved in the methylene chloride, stir, prepare solution-1.With respect to tri acetyl cellulose to be red, the blue and yellow organic pigment of concentration (quality %) interpolation of below table 6.Suitably adjust concentration dichloromethane so that solution-1 can obtain target film thickness and be easy to coating.

Coating above-mentioned dispersion liquid-1 on the protective clear layer of preparing through the method identical with embodiment 1 obtains the scattering layer 16 of the about 30 μ m of thickness.Further on scattering layer 16, be coated with above-mentioned solution-1, form the dyed layer 18 of the about 30 μ m of thickness, obtain light diffusion layer 31～34.

Making is used to measure inner absorbance, inner attenuation rate and internal transmission rate with the film (measuring with sample 31～34) of dyed layer 18 same compositions.This measures method for making with sample 31～34 with reference to the method for making of the mensuration among the embodiment 1 with sample 11～14.Film thickness is about 30 μ m.Use the inside absorbance of commercially available these films of spectrophotometric determination, inner attenuation rate, internal transmission rate.

In addition, make the film that does not add pigment and only contain polymkeric substance.The value of using this film to record as benchmark (baseline), is carried out the mensuration of above-mentioned film, obtain thus deducted after the loss that surface reflection produced, inner absorbance and internal transmission rate.The result lists in table 6.

[table 6]

< evaluation of mist degree >

In order to estimate the mist degree of light diffusion layer, the film of scattering layer 16 same compositions of making and the foregoing description 3 (mist degree is measured and used sample).This mist degree is measured with the method for making of sample and is measured the method for making with sample with reference to the mist degree among the embodiment 1.

Use haze meter (Japanese electric look Industrial Co., Ltd, NDH2000) that the mist degree of made is measured and measure with sample, mist degree is about 92%.

< evaluation of picture whiting >

On the transmission-type liquid crystal display element of the formation of Fig. 7, give above-mentioned light scattering layer 31～34, carry out the evaluation of light diffusion layer.Liquid crystal panel uses the liquid crystal panel of VA type, as the cold-cathode tube of the main wavelength of use backlight for about 435nm, about 545nm and about 615nm.And oblique 45 degree shine with the promptly about 100lx of the illumination that forms general level of activity with fluorescent light from picture the place ahead, estimate the whiting of picture.Picture is a black display during evaluation.

Its result, the sample that inner absorbance is high more, the whiting degree is low more.As long as the inside absorbance under the main wavelength of the light that sends from back light is 0.014 just can be practical; Be 0.029 almost not observe whiting when above; Particularly the inside absorbance under the main wavelength of the light that sends from back light is the sample 33 and sample 34 more than 0.056, shows good black.

To the transmission-type liquid crystal display element of the evaluation that is used for above-mentioned picture whiting, use nitometer (TOPCON of Co., Ltd., BM-7FAST) to measure front face brightness and brightness angle distribution in the horizontal direction.Picture is formed to be measured after white shows.Use backlight before injecting liquid crystal panel the half value overall with of the angle distribution of the brightness of (before being equivalent to inject the protective clear layer 26 of Fig. 7) be about 30 degree., spread in the light diffusion layer up front through liquid crystal panel from this light backlight, the result is that the half value overall with all becomes about 70 degree in arbitrary light diffusion layer.

For the picture of the available liquid crystal panel that possesses the field angle compensate film, the half value overall with of its brightness angle distribution is about 70 degree, although can confirm thus to have used the backlight of high directivity, has the angle distribution degree that obtains the necessary brightness of sufficient field angle.

For front face brightness, as shown in table 7, the interpolation concentration of organic pigment is high more, and front face brightness is low more.As long as the inside absorbance under the main wavelength of the light that sends from back light is below 0.062, can obtain and above front face brightness, the brightness angle distributed degrees of the picture equal extent of the available liquid crystal panel that possesses the field angle compensate film.

[table 7]

More than, can know by embodiment 1～3, although be the formation of not using the field angle compensate film, but also obtained the roughly equal field angle of picture with the available liquid crystal panel that possesses the field angle compensate film shown in Figure 10.

And; Can know by embodiment 1～3; Be equivalent to the light diffusion layer of about scope below 0.062 through the inside absorbance under the main wavelength that is formed on the light that sends from back light, can access and to alleviate whiting well and have front face brightness and the LCD of brightness angle distributed degrees more than the picture equal extent with the available liquid crystal panel that possesses the field angle compensate film shown in Figure 10.Particularly when the inside absorbance under the main wavelength of the light that sends from back light is 0.028～0.062 scope, obtained good characteristic.

In addition, possess the LCD of the light diffusion layer of embodiment 1～3, image blurring by due to the light diffusion layer takes place hardly.

In addition, in the past, in the light diffusion layer of transmissive liquid crystal display device, do not add colorant.This be because, do not expect at first and utilize colorant to prevent reduction, and might worry that colorant absorbs from the light of backlight and cause brightness significantly to reduce by outer photogenic contrast, infer that reason is not initiatively added colorant.But, shown in the result of embodiment 1～3,, also can appear and brightness more than the available liquid crystal display device equal extent, and the contrast that can suppress to be caused by outer photoconduction reduces even add colorant.

[embodiment 4]

< making of light diffusion layer >

Method with shown in following is made light diffusion layer 41～45.

At first, likewise operate, prepare protective clear layer with embodiment 1.

On the other hand; In ethyl acetate, add polymethylmethacrylate, respectively as red, blueness and yellow organic pigment, C.I. paratonere (Pigment Red) 48:3 (adret pigment Co., Ltd.), C.I. alizarol saphirol (Pigment Blue) 15:1 (copper compound) (adret pigment Co., Ltd.), C.I. pigment yellow (Pigment Yellow) 14 (adret pigment Co., Ltd.); Further add alumina particulate (mean grain size 1.1 μ m), prepare dispersion liquid after stirring.

Wherein, with respect to polymethylmethacrylate to be red, the blue and yellow organic pigment of concentration (quality %) interpolation of below table 8.And, add 5 mass parts alumina particulates with respect to 100 mass parts polymethylmethacrylates.

Suitably adjust ethyl acetate concentration so that above-mentioned dispersion liquid can access the light diffusion layer of target thickness and be easy to coating.This dispersion liquid is coated on the above-mentioned protective clear layer, obtains the light diffusion layer 41～45 of the about 30 μ m of thickness.

The composition behind the alumina particulate has only been removed in making from the light diffusion layer of above-mentioned composition film (measuring with sample 41～45) is used to measure inner absorbance, inner attenuation rate and internal transmission rate.Measure method for making with sample 41～45 with reference to the method for making of the mensuration among the embodiment 1 with sample 11～14.Use the inside absorbance of commercially available these films of spectrophotometric determination, inner attenuation rate, internal transmission rate.

In addition, make the polymer film from above-mentioned composition, removed the composition behind alumina particulate and the organic pigment.The value of using this film to record as benchmark (baseline), is carried out the mensuration of above-mentioned film, obtain the loss that surface reflection produced inside absorbance, inner attenuation rate and the internal transmission rate afterwards of having deducted thus.The result lists in table 8.

[table 8]

< evaluation of mist degree >

In order to estimate the mist degree of light diffusion layer, making is not added organic pigment and is only added the alumina particulate (mean grain size 1.1 μ m) of same concentrations, and thickness is the polymer film (mist degree is measured and used sample) of about 30 μ m.This mist degree is measured with the method for making of sample and is measured the method for making with sample with reference to the mist degree among the embodiment 1.

Use haze meter (Japanese electric look Industrial Co., Ltd, NDH2000) that the mist degree of made is measured and measure with sample, mist degree is about 77%.

< evaluation of picture whiting >

On the transmission-type liquid crystal display element of the formation of Fig. 7, give above-mentioned light scattering layer 41～45, carry out the evaluation of light diffusion layer.Liquid crystal panel uses the liquid crystal panel of IPS type, as the cold-cathode tube of the main wavelength of use backlight for about 435nm, about 545nm and about 615nm.And oblique 45 degree shine with the promptly about 100lx of the illumination that forms general level of activity with fluorescent light from picture the place ahead, estimate the whiting of picture.Picture is a black display during evaluation.

Its result, the sample that inner absorbance is high more, the whiting degree is low more.As long as the inside absorbance under the main wavelength of the light that sends from back light is 0.014 just can be practical; Be 0.020 when above; Almost do not observe whiting; Particularly the inside absorbance under the main wavelength of the light that sends from back light is the sample 43～sample 45 more than 0.029, shows good black.

To the transmission-type liquid crystal display element of the evaluation that is used for above-mentioned picture whiting, likewise operate with embodiment 1, measure the brightness angle distribution.In addition; Brightness angle measure of spread as the light diffusion layer that is used for brightness angle Determination of distribution is added with the organic pigment of measuring shown in the sample 43 of above-mentioned table 8 with sample 41 and 42, and is added with the alumina particulate of 5 mass parts or 10 mass parts with respect to 100 mass parts polymethylmethacrylates.

Employed backlight inject liquid crystal panel before the half value overall with of brightness angle distribution of (before being equivalent to inject the protective clear layer 26 of Fig. 7) be about 47 degree., spread in the light diffusion layer up front through liquid crystal panel from this light backlight, the result is as shown in table 9, and the half value overall with all becomes more than about 70 degree in arbitrary light diffusion layer.

[table 9]

The picture that possesses the available liquid crystal panel of field angle compensate film; The half value overall with of its brightness angle distribution is about 70 degree; Can confirm thus; When the half value overall with of using the brightness angle distribution was 47 degree backlight, the measure of spread of brightness angle had the angle distribution degree of the necessary brightness of the sufficient field angle of acquisition with sample 41.

Can know by embodiment 4; In the half value overall with of using the brightness angle distribution during for about 47 degree backlight; The light diffusion layer that is equivalent to about scope more than 0.020 through the inside absorbance under the main wavelength that is formed on the light that sends from back light; Can alleviate whiting well, and field angle disperses fully, the half value overall with of brightness becomes more than about 70 degree.Particularly when the inside absorbance under the main wavelength of the light that sends from back light is the scope more than 0.029, obtained good characteristic.

Image blurring by due to the light diffusion layer takes place in LCD hardly that in addition, have the light diffusion layer of embodiment 4.

[embodiment 5]

< making of the light diffusion layer of double as protective seam >

Make the light diffusion layer 51 of double as protective seam with the method shown in following.

In ethyl acetate, add the polymethylmethacrylate and red, blue, yellow organic pigment same, and further add alumina particulate (mean grain size 1.1 μ m), prepare dispersion liquid after stirring with embodiment 4.

In addition, add 20 mass parts alumina particulates with respect to polymethylmethacrylate 100 mass parts.And; As red, blue and yellow organic pigment, use C.I. paratonere (Pigment Red) 48:3 (adret pigment Co., Ltd.), C.I. alizarol saphirol (Pigment Blue) 15:1 (copper compound) (adret pigment Co., Ltd.), C.I. pigment yellow (Pigment Yellow) 14 (adret pigment Co., Ltd.) respectively.Add 0.392 mass parts organic red pigment, the blue organic pigment of 0.072 mass parts, 0.120 mass parts yellow organic pigment with respect to polymethylmethacrylate 100 mass parts.

This dispersion liquid is coated on the stainless steel substrate of surface smoothing, makes solvent dry substantially, make membranaceous sample thus, resulting membranaceous sample is pulverized, and then drying under reduced pressure.The particle of gained sample with the polymethylmethacrylate of 3 times of amounts mixed, and after 230 ℃ of use double screw extrusion machines mixed, it was membranaceous using the single screw extrusion machine extrusion molding in 270 ℃, batches with roller.As above operation is made into the light diffusion layer 51 of double as protective seam.

The light diffusion layer 42 with embodiment 4 is identical respectively for the light diffusion layer 51 organic pigment concentration of the double as protective seam of embodiment 5 and the addition of alumina particulate, thinks thus and can bring into play the effect same with the light diffusion layer of embodiment 4 42.

[embodiment 6]

< making of the light diffusion layer of double as adhesive phase >

With the method shown in following, make the light diffusion layer 61 of double as adhesive phase.

Will be by butyl acrylate: acrylic acid: the acrylic acid series polymeric compounds of the weight-average molecular weight about 100,000 that the multipolymer of acrylic acid-2-hydroxyl ethyl ester=100: 5: 0.1 (weight ratio) constitutes be dissolved in the ethyl acetate, and the concentration of adjustment multipolymer is the solution of about 30 quality %.In aforesaid propylene acid based polymer solution, adding with respect to polymer solids composition 100 mass parts is the CORONATE L that makes of the Japanese polyurethane as the isocyanate-based multi-functional compounds (Polyurethane) society of 4 mass parts and adjuvant (KBM403, Shin-Etsu Chemial Co., Ltd make) 0.5 mass parts, alumina particulate (mean grain size 1.1 μ m) 5 mass parts and redness, blueness, yellow organic pigment, the preparation binder solution.

As red, blue and yellow organic pigment, use C.I. paratonere (Pigment Red) 48:3 (adret pigment Co., Ltd.), C.I. alizarol saphirol (Pigment Blue) 15:1 (copper compound) (adret pigment Co., Ltd.), C.I. pigment yellow (PigmentYellow) 14 (adret pigment Co., Ltd.) respectively.In addition, red, blue and yellow organic pigment adds 0.098 mass parts, 0.018 mass parts, 0.030 mass parts respectively with respect to the above-mentioned multipolymer of 100 mass parts.

Add the solvent (ethyl acetate) that is used to adjust viscosity; This binder solution is coated on the mould release membrance (the polyethylene terephthalate base material: Diafoil MRF38, Mitsubishi Chemical's polyester (Polyester) are made); And to make its dried thickness be 25 μ m; Then, use the heated air circulation type oven drying, form the adhesive phase that comprises scatterer and colorant.Use this adhesive phase that the protective clear layer 26 in the light polarizing film 28 and the outside is fit together.

The organic pigment concentration of the light diffusion layer 61 of the double as bonding coat of embodiment 6 and the addition of the alumina particulate light diffusion layer 42 with embodiment 4 respectively are identical, think thus and can bring into play the effect same with the light diffusion layer of embodiment 4 42.

The disclosed full content of submitting on June 9th, 2009 of Japanese patent application 2009-138442 is introduced this instructions through reference.

Whole documents, patented claim and the technical standard that this instructions is put down in writing and specifically and respectively having put down in writing through the ground of equal extent when introducing each document, patented claim and technical standard through with reference to being introduced in this instructions.

Claims

1. transmissive liquid crystal display device, it has at least:

Back light;

Light control unit is used to control the direction of light property of sending from said back light;

The transmission-type liquid crystal box; With

Said transmission-type liquid crystal box and said light diffusion layer dispose in the side near said light control unit successively.

2. transmissive liquid crystal display device as claimed in claim 1, wherein, the inside absorbance of said light diffusion layer under the main wavelength of the light that sends from said back light is more than 0.014.

3. according to claim 1 or claim 2 transmissive liquid crystal display device, wherein, the inside absorbance of said light diffusion layer under the main wavelength of the light that sends from said back light is more than 0.020.

4. like each described transmissive liquid crystal display device in the claim 1～3, wherein, the inside absorbance of said light diffusion layer under the main wavelength of the light that sends from said back light is 0.028～0.062.

5. like each described transmissive liquid crystal display device in the claim 1～4, wherein, the said scatterer in the said light diffusion layer to contain concentration high in the said liquid crystal cell side of said light diffusion layer film thickness direction.

6. like each described transmissive liquid crystal display device in the claim 1～5; Wherein, said light diffusion layer is in said light transmission polymkeric substance, to disperse said scatterer and scattering layer that forms and the lamilated body that contains the dyed layer of said light transmission polymkeric substance and said colorant.