JP2001166140A - Polarizing member, surface light source and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a polarizing member such that a liquid crystal display device having high luminance which hardly causes color irregularity in a wide viewing angle from the front view to oblique view can be formed. SOLUTION: The polarizing member has a cholesteric liquid crystal layer 1 having the Grandjean alignment, a 1/4 wavelength plate 3 on one or both surfaces of the layer 1, and a light-diffusing layer 2 containing colorless transparent particles, and if necessary, at least either a polarizing plate 4 or a phase difference plate. The surface light source 8 and the liquid crystal display device are produced by using that polarizing member. In the polarizing member, light in an oblique direction can be efficiently diffused by the light-diffusing layer so that light of various colors is mixed to produce a uniform color in all directions, that color irregularity can be prevented and that the color instensity can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing member capable of forming a high-brightness liquid crystal display device in which color unevenness hardly occurs at a wide viewing angle in a frontal and oblique view.

[0002]

BACKGROUND OF THE INVENTION Conventionally, a polarizing member comprising a cholesteric liquid crystal layer having a Grand Jean orientation and a quarter-wave plate is disposed on a side light type light guide plate for forming a backlight for the purpose of increasing the brightness of a liquid crystal display device or the like. What was done was known. This utilizes the property of the cholesteric liquid crystal layer of the Grand Jean orientation that separates the incident natural light into reflected light and transmitted light composed of one of left and right circularly polarized lights, and circularly polarizes the outgoing light from the light guide plate, thereby reducing it to 1/4. By supplying linearly polarized light through a wavelength plate and supplying the linearly polarized light to the polarizing plate, absorption loss due to the polarizing plate can be suppressed and luminance can be improved.

[0003] However, the conventional polarizing member has a problem that color unevenness occurs when the member is viewed obliquely. The helical pitch and the 1
There is also a proposal to reduce the color unevenness by regulating the refractive index at / 4 wavelength (Japanese Patent Application No. 10-73184), but it has not been a satisfactory improvement measure. However, there still remains a problem of coloring in various colors in a perspective direction or the like, such as coloring in blue. Therefore, at present, when used in a liquid crystal cell in which coloring due to perspective is highly suppressed by the MVA method, the super IPS method, or the like, the original characteristics of the cell cannot be fully utilized.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to develop a polarizing member capable of forming a high-brightness liquid crystal display device in which color unevenness is less likely to occur in a wide viewing angle in front and in a perspective.

[0005]

According to the present invention, there is provided a cholesteric liquid crystal layer having at least one of a quarter-wave plate and a light diffusion layer containing non-colored transparent particles on one or both sides of a cholesteric liquid crystal layer having a Grandian orientation. A polarizing member having at least one of the retardation plates, and a surface light source and a liquid crystal display device characterized by using the polarizing member.

[0006]

The above-mentioned coloring problem due to oblique viewing occurs because the optical axis relation of the quarter-wave plate or the polarizing plate adjusted with respect to the front direction is shifted by oblique viewing, and the color is shifted due to the difference in the way of oblique viewing. It is likely to change. According to the polarizing member of the present invention, light in an oblique direction can be efficiently diffused by the light diffusing layer, various color lights can be confused, the same color can be obtained in all directions, color unevenness can be prevented, and color intensity can be reduced. Further, the state of circularly polarized light by the cholesteric liquid crystal layer or linearly polarized light through the quarter-wave plate can be efficiently maintained by controlling the diffusion characteristics by the light diffusion layer. As a result, it is possible to form a liquid crystal display device which is excellent in luminance and display quality with a wide viewing angle in the front and in the oblique direction while preventing luminance unevenness while improving luminance.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A polarizing member according to the present invention has a 1 /
It comprises at least a four-wavelength plate and a light diffusion layer containing uncolored transparent particles, and if necessary, at least one of a polarizing plate and a retardation plate. An example is shown in FIG. 1 is a cholesteric liquid crystal layer having a Grand Jean orientation, 2 is a light diffusion layer, and 3 is a quarter-wave plate. The figure shows a liquid crystal display device, in which reference numerals 4 and 41 denote polarizing plates, 5 a liquid crystal cell, and 8 a light source.

There is no particular limitation on the cholesteric liquid crystal layer of the Grand Jean orientation, and an appropriate material exhibiting the characteristic of transmitting incident natural light on one of left and right circularly polarized lights and reflecting the other can be used. By using a cholesteric liquid crystal layer exhibiting such reflection / transmission characteristics, light from a light source such as a backlight is made incident to obtain transmitted light in a predetermined polarization state, and the transmitted light is supplied to a polarizing plate in a state where it is hardly absorbed by a liquid crystal. Brightness can be improved by increasing the amount of light available for display and the like.

In the above, when the light reflected by the cholesteric liquid crystal layer is inverted through the reflection layer or the like and re-enters the cholesteric liquid crystal layer, part or all of the light can be transmitted as light of a predetermined polarization state. By utilizing the reflected light, the amount of light transmitted through the cholesteric liquid crystal layer can be increased to further improve the brightness of a liquid crystal display or the like.

The cholesteric liquid crystal layer may have a configuration in which two or three or more layers are overlapped in a combination of those having different helical pitches of the Grandian orientation and therefore different reflection wavelengths. With such superimposition, it is possible to obtain circularly polarized light that reflects in a wide wavelength range such as the visible light range, and based on this, it is possible to obtain transmitted circularly polarized light in a wide wavelength range. When superimposing cholesteric liquid crystal layers having different helical pitches of the Grandian orientation, it is preferable to superimpose the cholesteric liquid crystal layers so that the helical pitches are in the order of magnitude from the viewpoint of improving light use efficiency and, consequently, improving brightness. Is 1 / to the side where the helical pitch of the superimposed body is smaller.
It is preferable to dispose a four-wavelength plate from the viewpoint of, for example, reducing coloration due to perspective.

The cholesteric liquid crystal layer exhibiting the above-mentioned reflection and transmission characteristics can be obtained as a liquid crystal polymer film or the like. It can be obtained as a layer or the like. The superposed layer can be formed by a recoating method or the like.

The material for forming the transparent substrate is not particularly limited, but generally a polymer is used. Examples of the polymer include cellulosic polymers such as cellulose diacetate and cellulose triacetate; polyester polymers such as polyethylene terephthalate and polyethylene naphthalate; acrylic polymers such as polycarbonate polymers and polymethyl methacrylate; polystyrene and acrylonitrile / styrene. Styrene polymers such as copolymers, polyethylene and polypropylene, polyolefins having a cyclo or norbornene structure, olefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, and amide polymers such as nylon and aromatic polyamides. can give.

Further, imide polymers, sulfone polymers, polyethersulfone polymers, polyetheretherketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, Oxymethylene-based polymers, epoxy-based polymers and blends of the above-mentioned polymers, and polyester-based, acrylic-based, urethane-based and amide-based, silicone-based and epoxy-based polymers and the like that are cured by heat or ultraviolet irradiation, etc. are also used as the transparent substrate. Can be used to form A transparent substrate having excellent isotropy, such as a cellulosic film, is preferably used.

On the other hand, the quarter-wave plate disposed on one side or both sides of the cholesteric liquid crystal layer aims at linearly polarizing the reflected light and / or transmitted light consisting of circularly polarized light by the cholesteric liquid crystal layer. By arranging the plate so that its transmission axis coincides as closely as possible with the vibration plane of the linearly polarized light transmitted through the quarter-wave plate, absorption loss can be prevented and the luminance can be further increased. Examples of the quarter-wave plate include birefringent films composed of stretched films of various polymers, oriented films of liquid crystal polymers such as discotic and nematic, and those in which the oriented liquid crystal layer is supported on a transparent substrate. Appropriate conventional ones can be used.

The polymer forming the birefringent film may be an appropriate polymer such as those exemplified for the transparent substrate described above. Above all, a polymer having excellent crystallinity, such as a polyester-based polymer or polyetheretherketone, can be preferably used. The stretched film may be processed by an appropriate method such as uniaxial or biaxial. Further, a birefringent film in which the refractive index in the thickness direction of the film is controlled by a method of applying a contraction force and / or a stretching force while adhering to the heat-shrinkable film may be used.

The quarter-wave plate may be formed by laminating two or more retardation layers for the purpose of controlling optical characteristics such as retardation. Incidentally, a phase difference layer functioning as a 波長 wavelength plate and a phase difference layer exhibiting other phase difference characteristics, for example, a phase difference layer functioning as a 板 wavelength plate are superimposed on monochromatic light such as light having a wavelength of 550 nm. According to such a method, a plate functioning as a quarter-wave plate in a wide wavelength range such as a visible light region can be obtained. 1/4 which can be preferably used from the viewpoint of preventing color unevenness and the like
When the in-plane main refractive index is nx and ny and the main refractive index in the thickness direction is nz, the wave plate has the formula: (nx-nz) / (nx-n).
Nz defined in y) is from +0.5 to -2.5.

As described above, the light diffusing layer mixes various colored lights into the same color to prevent color unevenness due to perspective and to reduce coloring. Therefore, the light diffusing layer is provided on the same side as the 波長 wavelength plate arranged on one side or both sides of the cholesteric liquid crystal layer, but the arrangement position is arbitrary, for example, between the cholesteric liquid crystal layer and the ４ wavelength plate or the 波長 wavelength plate. It can be arranged at an appropriate position such as outside the plate. Also 1 /
When a polarizing plate or a retardation plate is provided outside the four-wavelength plate,
Appropriate layers including these and the outside thereof may be used as the arrangement position.

The light diffusion layer is formed as a layer containing uncolored transparent particles from the viewpoint of efficiently obtaining the above-mentioned diffusion effect. The light diffusion layer can be formed on a light diffusion sheet or the like manufactured by an appropriate method according to the related art such as a method of forming a resin containing transparent particles into a film or a method of coating a support film, but is preferably used. Those which can be used are those exhibiting pressure-sensitive adhesiveness. According to this, the cholesteric liquid crystal layer, the quarter-wave plate, the polarizing plate, the retardation plate, and the like can be bonded and integrated via the light diffusion layer, and there is an advantage that a separate bonding layer can be omitted to reduce the thickness. is there.

The light diffusion layer exhibiting the pressure-sensitive adhesive property can be formed by, for example, a method in which non-colored transparent particles are contained in an adhesive layer. For forming the adhesive layer, an appropriate adhesive substance such as an adhesive having an appropriate polymer such as an acrylic polymer, a silicone polymer, polyester, polyurethane, polyether or synthetic rubber as a base polymer can be used. Among them, those which are excellent in optical transparency, weather resistance, heat resistance and the like and are hardly caused to float or peel off under the influence of heat or humidity, such as acrylic adhesives, can be preferably used.

Examples of the acrylic pressure-sensitive adhesive include an alkyl ester of (meth) acrylic acid having an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group, and a butyl group; Based on an acrylic polymer having a weight average molecular weight of 100,000 or more, obtained by copolymerizing an acrylic monomer comprising an improving component such as hydroxyethyl (meth) acrylate in a combination having a glass transition temperature of 0 ° C. or lower. Polymers and the like are mentioned,
It is not limited to this.

Examples of the non-colored transparent particles include inorganic particles which may be conductive, such as silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like. One or more kinds of appropriate particles such as organic particles made of a crosslinked polymer or the like can be used.

In the present invention, the compatibility between the suppression of the brightness decrease in the front direction due to the reduction in the amount of light in the front direction and the suppression of the coloring in the oblique direction and the color unevenness due to the same colorization, and the wide visual field of the front and oblique views. The total light transmittance is 85% or more, particularly 87% or more, particularly 90%, in order to obtain a liquid crystal display device having high brightness and excellent display quality without color unevenness at the corners.
As described above, the straight transmissivity is 5 to 50%, especially 6 to 40.
%, Especially 8 to 30% of the light diffusion layer can be preferably used.

Achievement of light transmittance and control of adhesive strength
Uncolored transparent particles that can be preferably used from the viewpoint of
Has an average particle size of 1 to 10 μm, preferably 9 μm or less, particularly 2 to 8 μm.
μm. In addition, it suppresses backscattering and
Rather than having good diffusibility, the use of uncolored transparent particles
Refractive index is n¹, The refractive index of the resin or adhesive layer containing it
To n²And the formula: 0.01 <┃n¹-N²┃ <
0.1, especially $ n¹-N ²┃ <0.09, especially −0.0
8 <n¹-N²Light with a combination satisfying <-0.01
Diffusion layers are preferred.

The amount of the non-colored transparent particles dispersed and contained in the light diffusion layer is appropriately determined based on the above-described light transmittance and the like. It is preferable to use 5 to 200 parts by weight, preferably 10 to 150 parts by weight, particularly 15 to 100 parts by weight, of non-colored transparent particles per 100 parts by weight (solid content). The thickness of the light diffusion layer can be determined according to the desired light transmittance, etc., but is generally 300 μm or less, especially 1 to 200 μm, particularly 5 to 10 μm.
The thickness is 0 μm.

The light diffusion layer formed of the adhesive layer is formed by, for example, a method of rolling a mixture of the adhesive substance and the uncolored transparent particles by a calender roll method, a coating method by a doctor blade method, a gravure roll coater method, or the like. A method of attaching a cholesteric liquid crystal layer, a quarter-wave plate, a polarizing plate, a retardation plate, or the like to a supporting base material in an appropriate manner, or using a separator as the supporting base material and diffusing light on the separator according to the above. It can be carried out by an appropriate method such as forming a pressure-sensitive adhesive layer and transferring it to another supporting substrate composed of a cholesteric liquid crystal layer or the like. The pressure-sensitive adhesive layer can also be formed as a superposed layer of different pressure-sensitive adhesives, such as a layer having no transparent particles on one or both sides of a transparent particle-containing layer.

If necessary, the polarizing member may be 1/4 as shown in the drawing.
One or two or more other appropriate optical layers such as a polarizing plate 4 and a retardation plate may be provided outside the wavelength plate 3. Such a polarizing plate aims at obtaining linearly polarized light for achieving a liquid crystal display and the like, and a retardation plate aims at compensating a phase difference due to birefringence of a liquid crystal cell and improving display quality. I do. When a polarizing plate is provided, usually, a １ ／ wavelength plate 3 is provided only on one side of the cholesteric liquid crystal layer 1 as shown in the figure, and a polarizing plate 4 is provided via the 波長 wavelength plate.

As the polarizing plate, an appropriate one that transmits linearly polarized light having a predetermined polarization axis and absorbs other light can be used, and the type thereof is not particularly limited. Generally, a polarizing film or a film having one or both surfaces protected by a transparent protective layer is used. Incidentally, as an example of the polarizing film, iodine and / or a dichroic dye is applied to a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene-vinyl acetate copolymer-based partially saponified film. Examples thereof include films that have been adsorbed and stretched, and polyene-oriented films such as polyvinyl alcohol dehydration products and polyvinyl chloride dehydrochlorination products.

The transparent protective layer provided on one side or both sides of the polarizing film as necessary can be formed of the polymer exemplified for the above transparent substrate. Above all, a transparent protective layer made of a polymer having excellent transparency, mechanical strength, heat stability, moisture shielding property and the like is preferable. The transparent protective layer can be formed by an appropriate method such as a method of applying a polymer liquid or an adhesive lamination method of a film.

On the other hand, a birefringent film or an oriented liquid crystal layer or the like having a suitable retardation according to the above-mentioned quarter-wave plate can be used as the retardation plate, and the optical characteristics such as the retardation can be controlled. It may be a laminate of two or more retardation layers for the purpose. The compensating retardation plate is usually arranged so as to be located between the polarizing plate and the liquid crystal cell.

In the above description, the cholesteric liquid crystal layer and the 1 /
The four-wavelength plate, the light diffusing layer, and the polarizing plate and the retardation plate as necessary may be simply superposed, but it is preferable to stabilize the quality by preventing displacement of the optical axis and to assemble the liquid crystal display device. It is laminated and integrated via an adhesive layer such as an adhesive layer for the purpose of improving efficiency and the like. It should be noted that the outer surface of the polarizing member may be provided with an adhesive layer for the purpose of adhering to another member such as a liquid crystal cell, if necessary, and when the adhesive layer is exposed on the surface until practical use. The surface may be temporarily covered with a separator or the like for protection such as prevention of contamination.

The polarizing member according to the present invention can be used for various applications according to the related art. In particular, it can be preferably used for forming a surface light source or a liquid crystal display device for the purpose of improving luminance or the like. In the liquid crystal display device, for example, as shown in FIG.
It can be formed by a method in which the polarizing plate 41 is disposed on one side of the liquid crystal cell 5 while the polarizing plate 41 is disposed on the other side of the liquid crystal cell via the wavelength plate 3 or the polarizing plate 4.

The surface light source has a light source 82 on the side surface as shown in FIG.
On the light emission side of the side light type light guide plate 81 in which
The polarizing member can be formed by a method in which the cholesteric liquid crystal layer 1 is disposed on the light guide plate side or the like. In the illustrated surface light source 8, a light source 82 is surrounded by a holder 83, and a polarizing member is provided on a light exit side of a light guide plate 81 provided with a reflective layer 9 on the bottom surface via a light diffusion sheet 7 and a light collection sheet 6. Is arranged.

According to the liquid crystal display device shown in FIG. 1, the light emitted from the surface light source 8 is diffused by the light diffusion sheet 7 and the optical path is controlled by the light collection sheet 6 so that the cholesteric liquid crystal layer 1 of the polarizing member is formed.
, Is separated into reflected light and transmitted light, and the transmitted circularly polarized light is diffused through the light diffusion layer 2 and is incident on the 波長 wavelength plate 3, through which it is linearly polarized and absorbed by the polarizing plate 4. The light passes through the liquid crystal cell 5 with little loss, and is emitted through the polarizing plate 41 on the viewing side.

In the above, the absorption loss by the polarizing plate 4 is small, and the reflected light by the cholesteric liquid crystal layer 1 is inverted by the reflecting layer 9 on the lower surface side of the light guide plate, re-enters the cholesteric liquid crystal layer and transmits, and the reflected light The brightness of the liquid crystal display device can be improved, for example, by improving the light use efficiency by using the light emitting device.

In forming a liquid crystal display device, any liquid crystal cell can be used. For example, an active matrix driving type represented by a thin film transistor type, a TN
Various types of liquid crystal display devices can be formed using appropriate types of liquid crystal cells, such as a simple matrix drive type represented by a liquid crystal or STN type, and a liquid crystal cell provided with a color filter.

In forming a liquid crystal display device or a surface light source, as shown in the figure, a polarizing plate 41 and a light diffusion sheet 7 on the viewing side, a light-collecting sheet 6 such as a prism sheet and a lens sheet, etc.
One or more appropriate optical sheets used for forming the liquid crystal display device such as the backlight 8 can be arranged at appropriate positions, and a compensating retardation plate can be arranged on the viewing side.

As the polarizing plate 41 on the viewing side, an appropriate one such as the above-mentioned polarizing member can be used. If necessary, an antiglare layer, an anti-reflection layer, or the like may be provided on the viewing side surface. Can be provided. The anti-glare layer scatters the external light reflected on the surface, and the anti-reflection layer suppresses the surface reflection of the external light, preventing the surface reflected light from causing glare or the like to impair the visibility of the transmitted light of the display device. It is performed for the purpose. Therefore, both the anti-glare layer and the anti-reflection layer can be provided to further improve the prevention of visual impairment due to surface reflected light.

The antiglare layer and the antireflection layer are not particularly limited, and can be formed as appropriate to exhibit the above functions. Incidentally, the antiglare layer can be formed by providing a light-scattering / reflecting fine uneven structure according to the above-mentioned light diffusion layer. In addition, the antireflection layer is formed by a vapor deposition method such as a vacuum deposition method, an ion plating method, or a sputtering method, a plating method, or a suitable coating method such as a sol-gel method. It can be formed by an interference film made of a coating film of a low refractive material such as.

[0039]

EXAMPLE 1 A cholesteric liquid crystal polymer was superimposed on a cellulose triacetate film having a thickness of 40 μm via a rubbing alignment film, and the alignment treatment was performed. The reflection center wavelength was 760 nm and 650 n.
m, a refractive index of 1.4 on the 430 nm side of the reflection center wavelength of the cholesteric liquid crystal layer having a four-layer structure of 550 nm or 430 nm.
3. From a polycarbonate having an Nz of -1.5 through an acrylic diffusion adhesive layer (particle content 25% by weight) having a refractive index of 1.47 and a thickness of 25 μm containing uncolored transparent particles having an average particle size of 4 μm. 1/4 wavelength plate
A polarizing plate was adhered and laminated on the 波長 wavelength plate via an acrylic adhesive layer containing no fine particles to obtain a polarizing member. The above diffusion type adhesive layer has a total light transmittance of 89% and a straight transmissivity of 19.5%.
belongs to. The straight transmissivity is defined as (total light transmittance−diffuse transmittance) / total light transmittance × 100.

Example 2 A polarizing member was obtained in the same manner as in Example 1 except that an acrylic adhesive layer containing no transparent particles and having a linear transmissivity of 99.5% was used instead of the diffusion adhesive layer.

Example 3 Straight transmittance 1 containing 30% by weight of transparent particles
A polarizing member was obtained in the same manner as in Example 1 except that the diffusion adhesive layer was 1.8%.

Example 4 Straight transmittance containing 5% by weight of transparent particles 27.
A polarizing member was obtained in the same manner as in Example 1 except that the diffusion type adhesive layer was 9%.

Evaluation Test The polarizing members obtained in Examples 1 to 4 were placed on a backlight composed of a sidelight type light guide plate having a reflective layer on the lower surface via the cholesteric liquid crystal side, and a luminance meter (manufactured by Topcon Corporation) was used.
BM7) and the color unevenness were examined.
The results are shown in the following table. The color unevenness was evaluated by the same color in all directions.

Example 1 Example 2 Example 3 Example 4 Luminance (nit) 2070 2090 1990 2080 Same colorability Good Bad Good Normal

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of a liquid crystal display device (polarizing member).

[Explanation of symbols]

1: Cholesteric liquid crystal layer 2: Light diffusion layer 3: 1
/ 4 wavelength plate 4, 41: polarizing plate 5: liquid crystal cell 8: surface light source

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadayuki Kameyama 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Nobuaki Maruoka 1-1-2 Shimohozumi, Ibaraki-shi, Osaka No. Nitto Denko Corporation F-term (reference) 2H049 BA02 BA05 BA07 BA42 BA43 BB03 BB49 BB51 BB63 BB65 BC04 BC22 2H091 FA08Z FA11Z FA31Z FA41Z FB02 FB12 FB13 FD06 GA06 GA17 LA19 LA20 4F100 AJ06 BA10 BA10 BA07BA10 DE01B DE01C EH46 EH462 GB41 HB00B HB00C JA11A JL10B JL10C JL13B JL13C JN01B JN01C JN18B JN18C YY00B YY00C

Claims (8)

[Claims] 1. A polarizing member comprising at least a quarter-wave plate and a light-diffusing layer containing uncolored transparent particles on one or both sides of a cholesteric liquid crystal layer having a Grandian orientation. 2. The polarizing member according to claim 1, wherein at least one of a polarizing plate and a phase difference plate is provided outside the quarter-wave plate. 3. The polarizing member according to claim 1, wherein the non-colored transparent particles of the light diffusion layer have an average particle size of 1 to 10 μm. 4. The polarizing member according to claim 1, wherein the light diffusing layer has a total light transmittance of 85% or more and a linear transmissivity of 5 to 50%. 5. The cholesteric liquid crystal layer according to claim 1, wherein the cholesteric liquid crystal layer is formed by superimposing helical pitches having different helical pitches of the Grandian orientation in the order of magnitude of the pitch, and the helical pitch of the superimposed body is small. Polarizing member having a quarter-wave plate on the side. 6. The light-diffusing layer according to claim 1, wherein the light-diffusing layer exhibits pressure-sensitive adhesiveness, the quarter-wave plate has an in-plane main refractive index of nx, ny, and a main refractive index in the thickness direction. Is nz,
Formula: Nz defined by (nx-nz) / (nx-ny) is +
A polarizing member having a thickness of 0.5 to -2.5. 7. A surface light source comprising the polarizing member according to claim 1. 8. A liquid crystal display device comprising the polarizing member according to claim 1.