JP2001228309A - Optical member integrated type light guide plate and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a light guide plate of an optical member integrated type which does not produce bright spot emission by air bubble inclusions. SOLUTION: The optical member integrated type light transmission plate which does not produce bright spot emission by air bubbles inclusions has at least upper and lower surface 1a, b, and an incident side surface 1c consisting of a side face between the upper and lower surfaces. An optical member 3 is adhered through an adhesive layer 2 on the surface which does not have an optical emission means of the upper and lower surfaces of the light guide plate 1 for performing an optical path conversion of incident light from the incident side surface in the direction other than the upper and lower surface through an optical emission means A formed on one of the upper and lower surfaces. After sticking by pressure the optical member through the adhesive layer on the surface which does not have the optical emission means of the upper and lower surfaces of the light guide plate, the pressurization adhesion processing is performed under the conditions of 65 deg.C or less and 0.3 or less and 0.3 MPa or more. A liquid crystal display device of transmission type or the reflection type- having a bright and legible display can be manufactured efficiency by using the light guide plate as a back light or a front light, and the optical member integrated type light guide plate of the above characteristics is obtained in the state with little warpage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate integrated with an optical member and capable of forming a transmissive or reflective liquid crystal display device having a bright and easy-to-view display and having excellent light use efficiency, and a method of manufacturing the same.

[0002]

BACKGROUND OF THE INVENTION In a transmission type liquid crystal display device and a reflection type liquid crystal cell, a surface light source device in which a light source is arranged on a side surface of a light guide plate having light emitting means formed of prismatic irregularities is used as a backlight of a transmission type liquid crystal cell. A reflective liquid crystal display device used for a front light has been proposed. When forming the liquid crystal display device, an optical member in which an optical member such as an anti-reflection film or a polarizing plate is bonded in advance to a light guide plate via an adhesive layer for the purpose of improving manufacturing efficiency and improving quality by controlling an optical axis. It is used as an integral type.

[0003] However, there is a problem that fine bubbles are mixed in the bonding process via the adhesive layer, and when the bubbles are visually recognized in the lighting mode, the transmitted light is irregularly reflected to emit bright spots, thereby greatly deteriorating the display quality. there were. Such bubbles are particularly likely to be mixed in at the end of the bonding process. Further, when an antireflection film is adhered and used for a front light, since the light guide plate is located on the viewing side, the visual obstruction due to bright spot emission is particularly large.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to develop a light guide plate integrated with an optical member, which does not generate luminescent spot light emission due to mixed bubbles.

[0005]

According to the present invention, there is provided a light emitting device having at least an incident side including upper and lower surfaces and a side surface between the upper and lower surfaces, and light incident from the incident side being formed on one of the upper and lower surfaces through light emitting means. An optical member characterized in that an optical member is adhered via an adhesive layer to upper and lower surfaces of a light guide plate that does not have a light emitting means in the light guide plate that changes the optical path in the other direction, and does not generate a bright spot due to mixed bubbles. On the member-integrated light guide plate, and on the light guide plate, the upper and lower surfaces of the light guide plate having no light emitting means,
An object of the present invention is to provide a method of manufacturing a light guide plate with an integrated optical member, characterized in that an optical member is pressure-bonded through an adhesive layer and then subjected to a pressure contact treatment at a temperature of 65 ° C. or less and 0.3 MPa or more.

[0006]

According to the present invention, it is possible to obtain a light guide plate integrated with an optical member which does not generate luminescent spot light emission due to mixed bubbles. And a reflection type liquid crystal display device can be formed with high manufacturing efficiency. Further, according to the manufacturing method of the present invention, a light guide plate integrated with an optical member having such characteristics can be obtained in a state where warpage is small.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical member integrated light guide plate according to the present invention has at least an incident side surface composed of upper and lower surfaces and side surfaces between the upper and lower surfaces, and the incident light from the incident side surface is formed on one of the upper and lower surfaces. An optical member is adhered via an adhesive layer to the upper and lower surfaces of the light guide plate which does not have the light emitting means on the upper and lower surfaces of the light guide plate which converts the optical path in the other direction of the upper and lower surfaces via the light emitting means. It can be manufactured by, for example, a method in which a light guide plate and an optical member are pressure-bonded via an adhesive layer and then subjected to a pressure contact treatment at 65 ° C. or lower and 0.3 MPa or higher. An example is shown in FIG. 1 is a light guide plate, 2 is an adhesive layer, and 3 is an optical member.

As the light guide plate, as shown in FIG.
a, a lower plate 1b opposed thereto, and a transparent plate-like object having at least an incident side surface 1c composed of a side surface between the upper and lower surfaces, through a light emitting means A having incident light from the incident side surface formed on one of the upper and lower surfaces. The optical path is changed in the other direction of the upper and lower surfaces.

The light guide plate may be of the same thickness as shown in the figure, or may have a thickness of the opposite end 1d facing the incident side surface 1c smaller than that of the incident side surface. .
Reducing the thickness of the opposing end is advantageous from the viewpoint of reducing the weight and improving the efficiency of incidence of incident light from the incident side surface to the light emitting means.
In the illustrated example, the light emitting means A is formed on the upper surface 1a. The light emitting means A has side surfaces 1e and 1f on both sides of the incident side surface 1c.

[0010] The light emitting means formed on one of the upper and lower surfaces of the light guide plate can be formed of an appropriate one exhibiting the above-mentioned emission characteristics. Rather than obtaining illumination light having excellent directivity in the front direction, a light emitting unit having a slope facing the incident side surface, particularly a light emitting unit formed of a prism-shaped unevenness, is preferable. The prismatic irregularities may be formed in a convex portion or a concave portion having an equilateral surface. However, it is preferable that the prism-shaped irregularities are formed in a convex portion or a concave portion formed of an optical path conversion slope and a flat surface from the viewpoint of light use efficiency. . FIG. 3 shows an example of the prismatic irregularities. a1 is an optical path changing slope, and a2 is a flat surface.

According to the above light guide plate, the incident light is transmitted through the light guide plate without scattering as much as possible, and is reflected by one of the upper and lower surfaces through the reflection by the light path changing slope of the light emitting means, especially the total reflection. It is possible to efficiently emit the light in a state excellent in the perpendicularity. By the way, in the light guide plate which is a scattering type emission means such as a dot or a grain-shaped unevenness, the emitted light has a large angle in the direction of about 60 degrees and dark emission in the front (vertical) direction. In addition, it is difficult to achieve a transmissive display, and in the case of a front light type, display light is scattered and cannot be visually recognized, so that practical use is difficult.

The light emitting means having the optical path changing slope formed by the above-mentioned prism-shaped unevenness or the like has excellent directivity of the reflected light through the optical path changing slope and is advantageous in the frontal direction which is advantageous for visual recognition in the transmission mode. Light can be efficiently formed, and a bright display with high luminance can be obtained. In addition, even with a front light type, display light can be efficiently transmitted in the front direction to obtain a bright and easy-to-view display.

A more preferable light emitting means for achieving the above-described characteristics such as the directivity in the front direction is 30 degrees relative to the reference plane of the light guide plate, that is, one of the upper and lower surfaces without the light emitting means. It has a repetitive structure of a slope inclined at an angle of up to 45 degrees and facing the incident side surface, and in particular, as illustrated in FIG. Optical path changing slope a1 (θ
₁ ) and a flat surface a2 (θ ₂ ) having an inclination angle of 0 to 10 degrees.
And a repetitive structure of prismatic irregularities composed of

In the above, the optical path changing slope a1 formed as a slope inclined downward from the incident side surface to the opposite end side reflects the light incident on the surface out of the incident light from the side surface, and reflects the light in the other direction of the upper and lower surfaces. (Optical surface side) The optical path is changed and supplied to the opposing surface (light emitting surface). In this case, by setting the inclination angle [theta] ₁ of the optical path changing slope to 30 to 45 degrees, the transmitted light is reflected with good perpendicularity to the light exit surface, and the emitted light (illumination light) having excellent directivity toward the front can be efficiently obtained. be able to. Preferred inclination angle theta ₁ of the optical path changing slopes from the viewpoint of directivity such as in the front, such as total reflection conditions based on the refraction by Snell's law of light transmitted inside the light guide plate by considering 35
44 degrees, especially 38-43 degrees.

On the other hand, if necessary, the flat surface a2 is transmitted, for example, in a backlight type transmissive liquid crystal display device by inverting, through a reflective layer as an optical member, the outgoing light consisting of the light reflected by the above-described optical path changing slope. Another object of the present invention is to provide a front-light-type reflection type liquid crystal display device, in which external light is incident, and the reflected light is transmitted through a reflection layer of a reflection type liquid crystal cell.
Inclination angle theta ₂ of the flat surface with respect to the reference plane 12 than the point according is preferably 10 degrees or less. Its amount of inclination theta ₂ increases the optical path changed by the refraction exceeds 10 degrees front direction disadvantageous in view decreases.

Although the inclination angle θ ₂ of the flat surface may be 0 degree (horizontal plane), if it is more than 0 degree, the transmission light incident on the flat surface is reflected and supplied to the optical path changing slope. The transmitted light can be made parallel, and the directivity of the reflected light via the optical path changing slope can be enhanced, which is advantageous for display. The preferable inclination angle θ ₂ of the flat surface is 8 degrees or less from the viewpoint of the increase in the amount of light in the front direction and the parallelization of the transmission light.
Especially below 5 degrees.

Further, a flat surface which is preferable from the viewpoint of the above-mentioned function is one in which the angle difference of the inclination angle θ ₂ is within 5 degrees, preferably within 4 degrees, particularly within 3 degrees of the entire light guide plate. within one degree of difference between the inclination angle theta ₂ between the flat surface of, within 0.3 degrees especially, particularly those set to within 0.1 degrees.
Angular difference such inclination angle theta _2, the inclination angle of the flat surface is assumed to be in the 10 degrees or less as described above. That it is intended to assume that with such small inclination angle θ within tolerance by suppressing the deflection of the display image due to refraction at the flat surface permeability as _2, which sets the observation point in the vertical direction near optimal It is an object of the present invention not to change the optimal viewing direction of a liquid crystal display device.

From the viewpoint of obtaining a bright display image, it is preferable that the display device has excellent external light incident efficiency and excellent transmission efficiency or output efficiency of the display image by the liquid crystal cell. From this point, it is preferable that the projection area of the flat surface with respect to the reference plane be 5 times or more, more preferably 10 times or more, especially 15 times or more of that of the optical path conversion inclined surface. Thereby, most of the display image by the liquid crystal cell can be transmitted through the flat surface. During transmission of the display image by the liquid crystal cell, the display image incident on the optical path conversion slope is reflected to the incident side and is not emitted from the surface on which the light emitting means is formed, or is transmitted through a flat surface based on the normal to the light emitting surface. The light is deflected in a direction largely different from the display image on the opposite end side and is emitted, and hardly affects the display image via the flat surface.

Therefore, it is preferable that the optical path conversion slope is not extremely located with respect to the pixels of the liquid crystal cell. By the way, if speaking in an extreme manner, if the optical path conversion slope overlaps the entire surface of the pixel, the display image in the vicinity of the vertical direction via the flat surface becomes hardly visible. Therefore, in order to prevent an unnatural display due to insufficient transmission of display light,
It is preferable to reduce the area where the pixel and the optical path changing slope overlap each other to secure a sufficient light transmittance through the flat surface.

In general, the pixel pitch of a liquid crystal cell is 100 to 3
In consideration of the above-mentioned points and the formability of prismatic irregularities, the optical path conversion slope is 40 μm or less, particularly 3 to 20 μm, particularly 5 to 15 μm based on the projection width with respect to the reference plane. Is preferably formed. Incidentally, the smaller the projection width is, the more advanced technology is required for forming the optical path conversion slope, etc., and when the top of the prismatic irregularities has a roundness having a radius of curvature of a certain value or more, a scattering effect appears and the display image is disturbed. May cause. In general, the coherent length of the fluorescent tube is 20
If the projection width of the optical path conversion slope is smaller than the point of about μm, diffraction or the like is more likely to occur, which tends to lower the display quality.

It is preferable that the distance between the optical path changing slopes is larger than the above-mentioned point. On the other hand, since the optical path changing slope is a substantial exit function part of the side incident light as described above,
If the interval is too wide, the lighting at the time of lighting may be sparse and the display may still be unnatural, and in view of them,
The repetition pitch P of the prismatic irregularities as illustrated in FIG.
Is preferably 50 μm to 1.5 mm. The pitch may be irregular, such as a random pitch or a random or regular combination of a predetermined number of pitch units, but is generally preferably a constant pitch.

In the case of the light emitting means having prismatic irregularities, moire may occur due to interference with the pixels of the liquid crystal cell. Moire can be prevented by adjusting the pitch of the prismatic irregularities, but as described above, the pitch of the prismatic irregularities has a preferable range. Therefore, a solution for a case where moire occurs in the pitch range becomes a problem. In the present invention, it is preferable to form the prism-shaped irregularities in an inclined state with respect to the reference plane of the incident side so as to prevent the moiré so that the prism-shaped irregularities can be arranged in a crossing state with respect to the pixels. In this case, if the inclination angle is too large, the reflection through the optical path conversion slope is deflected, causing a large deviation in the direction of the emitted light, and the anisotropy of the light emission intensity in the light transmission direction of the light guide plate becomes large, resulting in an increase in light intensity. The usage efficiency is also reduced, which is likely to cause a reduction in display quality.

From the above-mentioned point, the inclination angle of the prismatic irregularities in the arrangement direction of the incident side surface with respect to the reference plane, that is, the inclination angle of the prismatic irregularities in the ridge line direction is within ± 30 degrees, preferably within ± 28 degrees, particularly within ± 25 degrees. It is preferable that Note that ±
Means the direction of inclination with respect to the incident side surface.
In the case where the resolution of the liquid crystal cell is low and moiré does not occur, or when moiré can be neglected, the arrangement direction of the prismatic irregularities is preferably as parallel to the incident side surface.

The light guide plate can have an appropriate form as described above. In the case of a wedge shape or the like, the shape can be determined as appropriate, and the upper and lower surfaces thereof can have an appropriate surface shape such as a linear surface or a curved surface. Also, the optical path conversion inclined surface and the flat surface forming the light emitting means may be formed in an appropriate surface form such as a linear surface, a refraction surface, and a curved surface. Further, the prismatic irregularities may be composed of a combination of irregularities having different shapes and the like in addition to the pitch. Further, the prismatic irregularities may be formed as a series of convex portions or concave portions in which the ridge line is continuous, or may be formed as intermittent convex portions or concave portions which are arranged discontinuously in the ridge line direction with a predetermined interval. May be.

The shapes of the light exit surface and the incident side surface of the light guide plate are not particularly limited, and may be appropriately determined. In general, it is a flat light exit surface and an incident side surface perpendicular to the light exit surface. For the incident side surface, for example, a shape corresponding to the outer periphery of the light source, such as a curved concave shape, can be used to improve the incident efficiency. Further, an incident side structure having an introduction portion interposed between the light source and the light source may be employed. The introduction portion can have an appropriate shape according to the light source and the like.

The light guide plate can be formed of an appropriate material showing transparency according to the wavelength range of the light source. Incidentally, in the visible light region, for example, a transparent resin or glass represented by an acrylic resin, a polycarbonate resin, an epoxy resin, a norbornene resin, or the like is used. A light guide plate which does not exhibit birefringence or is formed of a material having low birefringence is preferably used. Generally, a light guide plate made of a material having a high refractive index is preferable to a point such as an emission angle and efficiency due to total reflection, and a transmission angle of incident light. However, in the case of a front light type, a high refractive index increases surface reflection. The refractive index is 1.55 or less, especially 1.53 due to the cause of a decrease in contrast.
Hereinafter, it is particularly preferable to use a light guide plate made of a material of 1.51 or less.

The light guide plate can be formed by a cutting method, and can be formed by an appropriate method. As a preferable manufacturing method from the viewpoint of mass productivity and the like, a method of pressing a thermoplastic resin under heating to a mold capable of forming a predetermined shape and transferring the shape, a thermoplastic resin heated and melted, or via a heat or solvent A method of filling a fluidized resin into a mold that can be molded into a predetermined shape, filling or casting a liquid resin that can be polymerized by heat, ultraviolet rays or radiation into a mold capable of forming a predetermined shape. Examples of the method include a polymerization treatment. Note that the light guide plate is formed as a laminate of parts made of the same or different materials, such as a sheet in which light emitting means such as prismatic irregularities are bonded to a light guide part that transmits light. Alternatively, it is not necessary that the material be formed as an integrated single layer of one kind of material.

The thickness of the light guide plate can be appropriately determined according to the size of the light guide plate and the size of the light source depending on the purpose of use. When used for forming a liquid crystal display device or the like, a typical thickness is 10 mm or less, especially 0.1
５5 mm, especially 0.3-5 mm. More preferable light guide plate such as achieving a bright display is incident light in the upper and lower direction,
In particular, the total light transmittance of the vertically incident light from the light emitting surface to the light emitting means forming surface is 90% or more, particularly 92% or more, particularly 95%.
With the above, the haze is 30% or less, especially 15% or less, especially 1
It is less than 0%.

As the optical member 3 bonded to the upper and lower surfaces of the light guide plate 1 having no light emitting means A via the adhesive layer 2 as in the example of FIG. 1, for example, an antireflection film, a reflection sheet, a hard coat film Transmission and reflection types, such as light-condensing sheets and light-diffusing sheets, such as a polarizing plate, a retardation plate and a brightness enhancement plate, a prism sheet and a lens sheet, and an elliptically polarizing plate and a circularly polarizing plate in which a polarizing plate and a retardation plate are laminated. When forming a liquid crystal display device of the type, an appropriate device disposed between the light guide plate and the liquid crystal cell can be used, and the type is not particularly limited.

Therefore, the optical member may be formed by laminating two or three or more optical layers as in the elliptically polarizing plate described above. The optical member in which two or three or more optical layers are laminated can also be formed by a method in which the optical members are sequentially laminated separately in a manufacturing process of a liquid crystal display device or the like, but an optical member in which the optical members are laminated in advance. Is advantageous in that it is superior in quality stability, assembling workability, and the like, and can improve the manufacturing efficiency of a liquid crystal display device and the like.

Incidentally, when the light guide plate is applied to a front light of a reflection type liquid crystal cell, the above-described antireflection film is used to reduce light path-converted light or incident external light on the light path conversion slope in the lighting mode or the external light mode. This is used for the purpose of preventing the reflected light from being reflected by the display light and overlapping the display light to lower the contrast, and preventing the light incident on the liquid crystal cell from being reduced by the lower surface reflection.

As the antireflection film, there can be used an appropriate film such as a film in which a coherent vapor-deposited film is formed on a supporting substrate made of a transparent film or the like, and there is no particular limitation. The use of an antireflection film also has an advantage that an antireflection layer having excellent durability can be provided. In addition, an appropriate material can be used as the support base material. Incidentally, examples thereof include polyester resins, acetate resins, polyethersulfone resins and polycarbonate resins, polyamide resins and polyimide resins, polyolefin resins and acrylic resins, polyvinyl alcohol resins and polystyrene resins, arylate resins. Examples thereof include those made of an appropriate polymer such as a system resin.

On the other hand, when the light guide plate is applied to a backlight of a transmissive liquid crystal cell, the reflection sheet inverts the light whose path has been changed on the light path changing slope in the lighting mode at the emission surface (lower surface) of the light guide plate. When used for display light or when external light is incident from the viewer side and reflected on the lower surface of the light guide plate, the reflected light is used as display light so that display can be performed in the external light mode in addition to the lighting mode. Used for such purposes. As the reflection sheet, for example, an appropriate sheet such as a sheet in which a light reflection layer formed of a metal or a dielectric multilayer film is formed on a support substrate formed of a film or the like can be used, and there is no particular limitation. A light diffusion type reflection sheet having a roughened light reflection surface may be used.

The hard coat film is used for the purpose of preventing a light guide plate from being damaged by contact with an adjacent optical member when the light guide plate is applied to a backlight or a front light of a transmission type or reflection type liquid crystal cell. If the light guide plate is damaged,
Like the mixed air bubbles, they tend to cause bright lines due to scattering. For the hard coat film, for example, a hard film made of a resin that is cured by radiation such as heat, ultraviolet rays, or an electron beam such as an acrylic, urethane, acrylic urethane, epoxy, or silicone resin is formed on a support substrate made of a transparent film or the like. Any suitable material such as those described above can be used, and there is no particular limitation. The hard coat film may also serve as an anti-reflection film or a reflection sheet in which the above-described anti-reflection layer, light reflection layer, and the like are protected by a hard film.

On the other hand, a polarizing plate is used for achieving a liquid crystal display through linearly polarized light when the light guide plate is applied to a backlight or a front light of a transmission type or reflection type liquid crystal cell, and is used on the viewing side or on the viewing side. It is integrated with the light guide plate as a rear polarizing plate. As a polarizing plate, for example, 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 is used.
Alternatively, a suitable material such as a polarizing film obtained by adsorbing a dichroic dye and stretching may be used without any particular limitation.

Accordingly, the polarizing plate may have a transparent protective layer on one or both sides of the polarizing film. For the formation of the transparent protective layer, an appropriate material such as the polymer exemplified in the above-mentioned supporting substrate can be used, and those having excellent transparency and mechanical strength, heat stability and moisture shielding property are preferably used. Can be The transparent protective layer can be formed by an appropriate method such as a method of applying a polymer or a method of bonding and laminating a film, and the thickness thereof can be appropriately determined. In general, the thickness is 500 μm or less, especially 1 to 300 μm, especially 5 to 200 μm.

The transparent protective layer may have a fine surface irregularity structure by including fine particles according to the above-mentioned light diffusion type reflection sheet. As the fine particles, for example, silica or alumina having an average particle size of 0.5 to 50 μm, titania or zirconia, tin oxide or indium oxide, cadmium oxide or antimony oxide, etc. Alternatively, appropriate transparent fine particles such as organic fine particles made of an uncrosslinked polymer or the like can be used.

When the light guide plate is applied to a backlight or a front light of a transmission type or reflection type liquid crystal cell, the phase difference plate is used for an appropriate purpose such as control of a phase difference and compensation of a viewing angle of the liquid crystal cell. Can be Therefore, as a phase difference plate,
For example, various wave plates such as a half wave plate and a quarter wave plate,
Those having an appropriate phase difference depending on the intended use, such as a phase difference capable of compensating for coloring due to birefringence of the liquid crystal layer and a phase difference capable of compensating for a viewing angle such as a widening of a viewing angle, can be used.

As an example of the above-mentioned retardation plate,
Examples include a birefringent film obtained by stretching a film made of a polymer or the like exemplified as the above support substrate, an alignment film of a liquid crystal polymer, and an alignment layer of a liquid crystal polymer supported by a film. In addition, a tilted oriented film in which the refractive index in the thickness direction is controlled can be used. Such an obliquely oriented film is obtained, for example, by bonding a heat shrinkable film to a polymer film and applying a shrinkage force by heating to stretch or / and shrink the polymer film, or obliquely align a liquid crystal polymer. be able to. The retardation plate may be one in which two or more retardation plates are laminated to control optical characteristics such as retardation.

Further, when the light guide plate is applied to a backlight of a transmissive liquid crystal cell, the above-mentioned brightness enhancing plate receives transmitted light from the light guide plate to obtain transmitted light in a predetermined polarization state and absorbs the light into the polarizing plate. It is used for the purpose of increasing the amount of light that can be used for a liquid crystal display or the like by supplying polarized light that is difficult to be emitted and improving the luminance. In addition, if necessary, the reflected light from the brightness enhancement plate is inverted through a reflection layer or the like and re-incident on the brightness enhancement plate, and a part or all of the light is transmitted as light in a predetermined polarization state, and the light transmitted through the brightness enhancement plate is transmitted. It can also be used in a method of increasing the amount and improving the luminance.

Accordingly, as a brightness enhancement plate, for example, a linearly polarized light having a predetermined polarization axis is transmitted and other light is reflected, such as a multilayered thin film of a dielectric or a multilayered laminate of thin films having different refractive index anisotropy. Those exhibiting characteristics, cholesteric liquid crystal layer,
Inject natural light, such as an cholesteric liquid crystal polymer oriented film or one that supports the oriented liquid crystal layer on a film substrate, such as one that reflects one of the left and right circularly polarized light and transmits the other light. As a result, an appropriate material that reflects linearly polarized light having a predetermined polarization axis or circularly polarized light having a predetermined direction and transmits other light can be used, and there is no particular limitation. The brightness enhancement plate is sometimes called a polarization separation plate or the like.

In the above-described brightness enhancement plate of a type that transmits linearly polarized light having a predetermined polarization axis, the transmitted light is incident on the polarization plate with the polarization axis aligned as it is, thereby efficiently absorbing the polarization plate while suppressing absorption loss. Can be transmitted. On the other hand, a brightness enhancement plate that transmits circularly polarized light, such as a cholesteric liquid crystal layer, can be directly incident on the polarizing plate.However, from the viewpoint of suppressing absorption loss, the transmitted circularly polarized light is converted to linearly polarized light through a retardation plate. It is preferable to make the light incident on the polarizing plate. By the way, 1
By arranging between a polarizing plate and a brightness enhancement plate using a / 4 wavelength plate, circularly polarized light can be converted to linearly polarized light.

A retardation plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region is, for example, a retardation layer that functions as a quarter-wave plate with respect to monochromatic light such as light having a wavelength of 550 nm. , For example, a method of superimposing a retardation layer functioning as a half-wave plate with the retardation layer exhibiting the above retardation characteristic. The cholesteric liquid crystal layer also has a structure in which two or three or more cholesteric liquid crystal layers are superimposed with a combination of those having different reflection wavelengths, so that a layer that reflects circularly polarized light in a wide wavelength range such as a visible light region can be obtained. Based on this, it is possible to obtain transmitted circularly polarized light in a wide wavelength range.

As described above, the optical member may be composed of a laminate of two or three or more optical layers. Incidentally, the above-mentioned retardation plate for optical compensation can be used as an elliptically polarizing plate or a circularly polarizing plate laminated with a polarizing plate. In addition, a brightness enhancement plate that transmits circularly polarized light can be used as a laminate with a quarter-wave plate, or a laminate with a polarizing plate added. Further, the above-described antireflection film or reflection sheet also serving as a hard coat film, and a laminate of two or more retardation plates are examples of an optical member composed of a laminate of two or more optical layers. Therefore, the combination of the optical layers in the case of forming an optical member composed of a laminate of two or three or more optical layers can be appropriately determined.

As shown in FIG. 1, the adhesive layer 2 for bonding the light guide plate 1 and the optical member 3 is formed by, for example, acrylic, silicone, polyester, polyurethane, polyamide, polyether, or fluorine. Adhesives and pressure-sensitive adhesives having an appropriate polymer such as a polymer, rubber, polyolefin or polyvinyl alcohol as a base polymer can be used, and there is no particular limitation. Among them, those having excellent optical transparency such as acrylic pressure-sensitive adhesives, exhibiting appropriate wettability, cohesiveness and adhesiveness and exhibiting excellent weather resistance and heat resistance can be preferably used. In addition, the moisture absorption rate is low due to the prevention of foaming and peeling phenomena due to moisture absorption, prevention of deterioration and warpage of optical characteristics due to differences in thermal expansion, and the formation of a high quality and durable optical member integrated light guide plate. An adhesive layer having excellent heat resistance is preferred.

From the viewpoint of suppressing interface reflection, it is preferable that the difference in refractive index between the light guide plate and the optical member is as small as possible. Adhesive layer, for example, natural or synthetic resins, especially,
Tackifying resin, glass fibers and glass beads, fillers and pigments, may contain appropriate additives such as antioxidants, and may be an adhesive layer or the like that contains fine particles and exhibits light diffusion. Good. The adhesive layer may be a superimposed layer of different compositions or types. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the adhesive force and the like, and is generally 1 to 500 μm,
Especially, it is 5 to 200 μm, especially 10 to 100 μm.

In bonding the light guide plate and the optical member,
An adhesive layer may be provided on one or both of the adhesive surfaces. The adhesive layer may be provided by, for example, directly applying the adhesive liquid on the adhesive surface of the light guide plate and / or the optical member by an appropriate developing method such as a casting method or a coating method, or by applying an adhesive on the separator according to the above. It can be performed by an appropriate method such as a method of forming a layer and transferring it to the light guide plate and / or the adhesive surface of the optical member.

In the above, the bonding treatment that does not cause luminescent spot light emission due to the mixed air bubbles is performed, for example, by pressing the light guide plate and the optical member through an adhesive layer and then applying the pressure to 65 ° C. or lower and 0.3 MPa.
It can be performed by applying a pressure contact treatment under the above conditions. In this case, when the processing temperature exceeds 65 ° C., it is advantageous in that defoaming is promoted by lowering the viscosity of the pressure-sensitive adhesive layer, but the resulting optical member-integrated light guide plate is warped due to a difference in linear expansion coefficient or the like. This is a hindrance when modularizing the liquid crystal display device. When an optical member having an inorganic oxide layer such as an antireflection film is integrated, the above-mentioned warpage tends to be particularly large.

On the other hand, if the above-mentioned pressurizing condition is less than 0.3 MPa, the microbubbles generated during the bonding process cannot be sufficiently removed, and the detoxifying effect due to the diffusion and dispersion of the bubbles in the adhesive layer is insufficient. Bright spot emission cannot be prevented. From the point of efficiently performing defoaming treatment and detoxification that does not cause bright spot emission while preventing warpage, the bonding treatment method is preferably 20 to 60 ° C., especially 3
At a temperature of 5 to 50 ° C and at least 0.4 MPa, especially 0.5
This is a method of performing pressure contact treatment at a pressure of 圧 力 20 MPa for 5 to 30 minutes.

The pressure contact treatment is preferably performed in an atmosphere of dry air or dry nitrogen. When air at atmospheric pressure is used as it is, dew condensation occurs when the pressure is reduced after pressurization, and fogging occurs on the surface of the optical member integrated light guide plate. The pressure contact process is
For example, it can be performed by an appropriate method such as a method using an autoclave. The above-mentioned temperature is based on that in a pressurized atmosphere. Incidentally, in the case of a light guide plate made of an acrylic resin, the weight deflection temperature is around 70 ° C., which is lower than the glass transition point. Occurs.

A light guide plate integrated with an optical member according to the present invention is a surface light source device or the like in which a light source is arranged on an incident side surface of the light guide plate, and is used as a backlight or a front light, and is used as a transmission type, a reflection type, or both. It can be preferably used for forming a liquid crystal display device of a type. As the light source, for example, a device such as a (cold or hot) cathode tube or a light emitting diode, an array body in which the tubes are linearly arranged, or a linear light guide plate for converting a point light source into a linear light emitting state was used. An appropriate light source such as a linear light source can be used. Also, when forming the surface light source device, a combination body in which appropriate auxiliary means such as a light source holder made of a reflection sheet or the like surrounding the light source is arranged to guide divergent light from the light source to the incident side surface of the light guide plate as necessary. You can also.

The liquid crystal cell forming the liquid crystal display device is also a twist type or non-twist type such as TN cell, STN cell, vertical alignment cell, HAN cell, OCB cell, guest host type or ferroelectric liquid crystal type. An appropriate transmission type or reflection type liquid crystal cell or the like can be used, and there is no particular limitation.

[0053]

Reference Example The surface of a mold previously processed into a predetermined shape was cut with a diamond bite to produce a core, which was mounted in the mold to form a core.
After heating to 0 ° C., it was filled with polymethyl methacrylate heated and melted at 260 ° C. and cooled to form a light guide plate having a light emitting means on the upper surface. It has a width of 80 mm, a depth of 60 mm, a thickness of the incident side of 1.2 mm, and a thickness of the opposite end of 0.
8 mm, the upper and lower surfaces are flat, the upper surface has prism-shaped irregularities parallel to the incident side surface at a pitch of 330 μm, and the inclination angle of the optical path conversion slope is in the range of 41.6 to 42.2 degrees.
The inclination angle of the flat surface changes in the range of 1 to 3 degrees, the inclination angle change of the nearest flat surface is within 0.1 degrees, the projection width of the optical path conversion slope to the lower surface is 8 to 19 μm, and the flat surface / optical path conversion The projected area ratio of the slope to the lower surface was 14 times or more. The light emitting means was formed at a position 5 mm away from the incident side surface.

Example 1 An antireflection film (optical member) having an antireflection film made of a vapor-deposited film of titanium oxide and silicon dioxide on one surface of a triacetylcellulose film and an adhesive layer on the other surface was provided with the adhesive layer interposed therebetween. The lower surface of the light guide plate obtained in the reference example (the side having no light emitting means) was pressed with a rubber roller and then pressed in a non-warmed (room temperature) autoclave containing dry air at 5M.
It was pressurized to Pa and subjected to pressure contact treatment for 30 minutes to obtain an optical member integrated light guide plate. The inside of the autoclave is 4
The temperature was raised to 6 ° C.

Example 2 An optical member-integrated light guide plate was obtained in the same manner as in Example 1 except that the processing pressure was 3 MPa. The temperature in the autoclave was 37 ° C.

Example 3 An optical member-integrated light guide plate was obtained in the same manner as in Example 1 except that the processing time was changed to 7 minutes.

Example 4 A light guide plate integrated with an optical member was obtained in the same manner as in Example 1 except that the treatment temperature was changed to 58 ° C. by heating.

Example 5 Example 1 except that only the pressure bonding treatment was performed without adding the heat adhesion treatment.
A light guide plate integrated with an optical member was obtained in accordance with the above.

Example 6 An optical member-integrated light guide plate was obtained in the same manner as in Example 1 except that the processing pressure was changed to 2 MPa. The temperature inside the autoclave was 32 ° C.

Example 7 An optical member-integrated light guide plate was obtained in the same manner as in Example 1 except that the processing time was changed to 3 minutes. The temperature in the autoclave was 45 ° C.

Example 8 An optical member-integrated light guide plate was obtained in the same manner as in Example 1, except that the treatment temperature was changed to 72 ° C. by heating.

Evaluation Test 1 In the light guide plate integrated with the optical member obtained in Examples 1 to 8, a cold cathode tube was arranged on the incident side surface of the light guide plate, and the light was turned on. Examined. It was confirmed by a microscope whether or not the bright spot was caused by bubbles. Further, the optical member-integrated light guide plate was placed on a flat plate so that the warp was convex, and the height of the float at the center (warp amount: maximum value) was examined using a thickness cage (JIS B7524).

The results are shown in the following table. Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Bright spots (pieces) 0 0 0 0 Many 2 5 0 Warpage (mm) ≤0.5 ≤0.5 ≤0.5 ≤0.5 ≤0.5 ≤0.5 ≤0.5 1.1

From the table, it can be seen that in Examples 1 to 4, there is no bright spot emission due to the mixed bubbles, and the warpage (maximum value) is suppressed to 0.5 mm or less. In Examples 5 to 7, the light was strongly emitted by the mixed bubbles at the time of lighting and was very conspicuous. Also, in Example 8, the sheet was greatly bent with a maximum warp of 1.1 mm and an average of 0.8 mm, and did not become flat even when cooled to room temperature. From the above, it can be seen that those obtained in Examples 1 to 4 can be used practically. Even when the pressure was reduced to the atmospheric pressure by using dry air, no fogging occurred on the surface due to dew condensation or the like.

Evaluation Test 2 In the light guide plate integrated with the optical member obtained in Examples 1 to 4, a cold-cathode tube was arranged on the incident side of the light guide plate, and it was arranged as a front light of a reflection type liquid crystal cell to display a reflection type liquid crystal display. The device was obtained. As a result, a very good display state was obtained in both the external light mode by non-lighting in a bright place and the lighting mode by lighting in a dark place. When using a light guide plate without an anti-reflection film for comparison as a reflective liquid crystal display device according to the above, in the external light mode, the display is glaring due to the surface reflection by the light guide plate, and the white blur display even in the lighting mode. It was hard to see

Evaluation Test 3 In the case where a light guide plate integrated with an optical member was obtained by using a reflection sheet or a polarizing plate instead of the antireflection film, the brightness due to the mixed bubbles was obtained in the same manner as in the above examples under the conditions of Examples 1 to 4. No point emission
And one with a small warpage was obtained. Incidentally, when according to Example 1, there was no bright spot emission due to the mixed bubbles, and the maximum value of the warp was also 0.5 mm or less. However, when according to Example 6, bright spot emission due to the mixed bubbles occurred, In the case of following Example 8, the average value of the warpage was 0.9 mm, the film was greatly bent, and did not become flat even when cooled to room temperature.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is an explanatory perspective view of an example of a light guide plate.

FIG. 3 is an explanatory side view of a light emitting unit.

[Explanation of symbols]

1: light guide plate (1a: upper surface 1b: lower surface 1c: incident side surface) A: light emitting means (a1: optical path conversion slope a2: flat surface) 2: adhesive layer 3: optical member

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nao Kokubo 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Takao Suzuki 1-1-2 Shimohozumi, Ibaraki-shi, Osaka No. Nitto Denko Corporation (72) Inventor Nobuyuki Kamo 1-1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Inside (72) Inventor Yoshimi Ota 1-1-2 Shimohozumi, Ibaraki City, Osaka Prefecture No. Nitto Denko Corporation F-term (reference) 2H038 AA55 BA06 2H042 BA10 BA12 BA14 BA20 2H091 FA23X FA23Z FB02 FC17 FD06 LA03 LA18

Claims (8)

[Claims] 1. A light emitting device having at least an incident side surface comprising upper and lower surfaces and a side surface between upper and lower surfaces thereof, and incident light from the incident side surface being formed on one of the upper and lower surfaces in the other direction of the upper and lower surfaces. An optical member integrated with a light guide plate, wherein an optical member is bonded via an adhesive layer to upper and lower surfaces of the light guide plate that does not have light emission means via an adhesive layer, and does not generate luminescent spots due to mixed bubbles. . 2. The optical member integrated light guide plate according to claim 1, wherein the optical member has at least an antireflection film, a reflection sheet, a hard coat film, or a polarizing plate. 3. The optical path conversion slope according to claim 1, wherein the surface on which the light emitting means is formed is inclined at an angle of 30 to 45 degrees with respect to the reference plane of the light guide plate, and faces the incident side surface. An optical member-integrated light guide plate having at least an inclination angle of 0 to 10 degrees and a repetitive structure of a flat surface having a projection area of 5 times or more the optical path conversion slope. 4. The light emitting device according to claim 3, wherein the light emitting means has a prism-shaped concave-convex portion having a projection width of 40 μm or less with respect to a reference plane of the light guide plate and a flat surface.
A pitch repeating structure is continuously formed on the upper surface of the light guide plate from one end to the other end in the direction of the incident side surface. The angle difference between the flat surface and the reference plane in the entire light guide plate is within 5 degrees, and the nearest flat surface is formed. An optical member-integrated light guide plate in which a difference in inclination angle between surfaces is within 1 degree. 5. The optical member integrated light guide plate according to claim 1, wherein the ridge line of the light emitting means is within ± 30 degrees with respect to the incident side surface. 6. A light emitting means having at least an incident side surface comprising upper and lower surfaces and a side surface between the upper and lower surfaces and transmitting light from the incident side surface to one of the upper and lower surfaces in the other direction of the upper and lower surfaces. An optical member is pressure-bonded via an adhesive layer to upper and lower surfaces of a light guide plate that does not have a light emission means, and then subjected to a pressure contact treatment at 65 ° C. or less and 0.3 MPa or more. A method for manufacturing a light guide plate integrated with an optical member. 7. The method according to claim 6, wherein the temperature is 5 to 3 ° C. or more.
A method for producing an optical member integrated light guide plate, which is subjected to a pressure contact treatment for 0 minutes. 8. The method of manufacturing an optical member integrated light guide plate according to claim 6, wherein a pressure contact treatment is performed in an atmosphere of dry air or dry nitrogen.