JP7098352B2 - Turning film for liquid crystal displays and liquid crystal displays - Google Patents

Description

The present invention relates to a liquid crystal display device and a turning film for a liquid crystal display device.

Conventionally, as optical sheets for liquid crystal display devices, there are various optical sheets having different optical characteristics, and a combination of these is used in a backlight unit for a liquid crystal display device. For example, as an optical film for the purpose of improving brightness, a polyester film in which a prism lens layer is provided on a base film made of polyester such as polyethylene terephthalate has been proposed (Patent Document 1).

Films made of polyethylene terephthalate are generally produced by a biaxial stretching method. However, polyethylene terephthalate is a crystalline resin and has a large birefringence. Therefore, when polyethylene terephthalate is formed into a film by the biaxial stretching method, molecular orientation occurs depending on the film position, and the variation in birefringence of the film becomes large. Therefore, when a film made of polyethylene terephthalate is used as an optical sheet of a liquid crystal display device, color unevenness and brightness variation due to polarization may occur in the liquid crystal display device.

International Publication No. 2009/020194

The present invention has been made based on such circumstances, and an object of the present invention is to provide a liquid crystal display device and a turning film for a liquid crystal display device capable of suppressing color unevenness and brightness variation due to polarization.

The liquid crystal display device of the present invention made to solve the above problems includes a liquid crystal panel, a light guide plate superimposed on the back surface side of the liquid crystal panel, and guiding light rays incident from the end surface to the front surface side, and the end surface of the light guide plate. A liquid crystal display device including one or a plurality of LED light sources arranged along the above, and a turning film superimposed between the liquid crystal panel and the light guide plate, wherein the turning film is a base material made of a transparent resin. It has a layer and a prism array arranged on the back surface side of the base material layer, and the liquid crystal panel has a liquid crystal cell and a back surface side polarizing plate arranged on the back surface side of the liquid crystal cell. The retardation value of the base material layer of the turning film is 180 nm or more and 415 nm or less, and the transmission axis of the back surface side polarizing plate of the liquid crystal panel has an angle α with the ridge line direction of the prism array of the turning film in a plan view. 0 degrees or more and less than 90 degrees, the ridgeline direction of the prism array of the turning film is parallel to the end surface of the light guide plate, and the slow axis of the base material layer of the turning film is the transmission axis of the back plate of the liquid crystal panel. It is characterized in that the angle of intersection with is set to (45-α / 2) degrees.

Since the liquid crystal display device includes a turning film having a substrate layer having a retardation value controlled and a prism array, the vibration direction of the light emitted from the turning film can be controlled. Further, in the liquid crystal display device, in a plan view, the transmission axis of the polarizing plate on the back surface side of the liquid crystal panel has an intersection α with the ridge line direction of the prism array of the turning film of 0 degrees or more and less than 90 degrees, and the ridge line of the prism array of the turning film. The direction is parallel to the end face of the light guide plate, and the slow axis of the substrate layer of the turning film has an intersection angle with the transmission axis of the polarizing plate on the back surface side of the liquid crystal panel at (45-α / 2) degrees. By aligning the vibration direction of the light emitted from the liquid crystal panel with the transmission axis of the polarizing plate on the back surface side of the liquid crystal panel, it is possible to reduce the loss of light and suppress the color unevenness and the variation in brightness due to the polarization.

It is preferable that the main component of the base material layer is polycarbonate. This improves the transparency and heat resistance of the base material layer.

The turning film may have at least one of a diffusion layer, a microlens array, or a reflective polarizing plate disposed on the surface side of the base material layer. As a result, the liquid crystal display device can improve the light emission characteristics from the turning film.

It is preferable that the prisms constituting the prism array have an acute angle on the back surface side. Thereby, the liquid crystal display device can select the shape of the slope of the prism according to the light emission characteristics from the light guide plate.

It is preferable that the refractive index of the prism array is 1.35 or more and 1.70 or less, and the refractive index difference between the prism array and the base material layer is 0.01 or more and 0.25 or less. Thereby, the liquid crystal display device can appropriately control the light entering characteristics to the base material layer.

It is preferable that the prism array has elasticity. As a result, the liquid crystal display device can prevent the light guide plate from being scratched due to the prism array coming into contact with the light guide plate.

It is preferable that the prism array is an ultraviolet curable resin molded product. As a result, the liquid crystal display device can use the ultraviolet curable resin when arranging the prism array on the base material layer, so that the turning film can be manufactured relatively easily.

The light guide plate has either a prism array or a lenticular lens array arranged on the surface side, and the ridge line direction of the surface of the light guide plate is perpendicular to the ridge line direction of the prism array of the turning film in a plan view. It should be done. Thereby, the liquid crystal display device can improve the optical performance such as the viewing angle.

The turning film of another invention made to solve the above-mentioned problems is a liquid crystal panel, a light guide plate superimposed on the back surface side of the liquid crystal panel, and guiding light rays incident from the end face to the front surface side, and the light guide plate described above. A turning film superimposed between the liquid crystal panel and the light guide plate in a liquid crystal display device including one or a plurality of LED light sources arranged along an end surface, the base material layer containing polycarbonate as a main component, and the base material layer thereof. It has a prism array arranged on the back surface side of the base material layer and a diffusion layer arranged on the front surface side of the base material layer to diffuse transmitted light rays, and the retardation value of the base material layer is 180 nm or more and 415 nm. The variation of the in-plane retardation value is 50 nm or less, and the slow axis of the base material layer intersects with the ridgeline direction of the prism array of the turning film at 45 degrees or more and less than 90 degrees in plan view. It is characterized by being done.

Since the turning film has a base material layer containing polycarbonate as a main component and a prism array whose retardation value is controlled, the vibration direction of the light emitted from the turning film can be controlled. Therefore, when the turning film is used in a liquid crystal display device, the vibration direction of the light emitted from the turning film is aligned with the transmission axis of the polarizing plate on the back surface side of the liquid crystal panel, so that the loss of light can be reduced. At the same time, it is possible to suppress color unevenness and brightness variation due to polarization.

In the present invention, the "front side" indicates the display surface side of the liquid crystal display device, and the "back surface side" indicates the side opposite to the front surface side. Further, the "main component" indicates that it is the most abundant component (for example, 50% by mass or more) on a mass basis. Further, "the prism has an acute angle" means that the intersection angle of the two slopes of each prism is less than 90 degrees. Further, "variation" indicates variation as a measurement term defined in JIS-Z8103 (2000), and a standard deviation is usually used.

As described above, the liquid crystal display device and the turning film of the present invention can suppress color unevenness and brightness variation due to polarization.

It is a figure which shows the schematic cross section of the liquid crystal display device in one Embodiment of this invention. It is a figure which shows the schematic cross section of the liquid crystal display device in embodiment different from the liquid crystal display device of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

[First Embodiment]
[Liquid crystal display device]
The liquid crystal display device 1 of FIG. 1 includes a liquid crystal panel 2, a light guide plate (light guide film 3) that is superimposed on the back surface side of the liquid crystal panel 2 and guides light rays incident from the end surface to the front surface side, and the light guide film 3. It includes one or a plurality of LED light sources 5 arranged along the end surface of the liquid crystal panel 2 and a turning film 4 superimposed between the liquid crystal panel 2 and the light guide film 3. The light guide film 3 and the turning film 4 are transparent because they transmit light rays. Further, the liquid crystal display device 1 further includes a reflector that is superimposed on the back surface side of the light guide film 3 and reflects the light rays incident from the front surface side to the front surface side (not shown).

<LCD panel>
The liquid crystal panel 2 has a liquid crystal cell 21, a back surface side polarizing plate 22 arranged on the surface (back surface) of the liquid crystal cell 21 on the turning film 4 side, and a surface (front surface) opposite to the turning film 4 side of the liquid crystal cell 21. ) Is provided with a surface-side polarizing plate 23. Specifically, the liquid crystal panel 2 has a back surface side polarizing plate 22 and a front surface side polarizing plate 23 arranged substantially parallel and at predetermined intervals, and a liquid crystal cell 21 arranged between them. As a whole, it has a plate shape with a substantially uniform thickness.

(LCD cell)
The liquid crystal cell 21 has a function of controlling the amount of transmitted light, and a known one is adopted. The liquid crystal cell 21 is generally a laminated structure composed of a substrate, a color filter, a counter electrode, a liquid crystal layer, a pixel electrode, a substrate and the like. A transparent conductive film such as ITO is used for this pixel electrode. The display modes of the liquid crystal cells include, for example, TN (Twisted Nematic), VA (Victoric Organic), IPS (In-Place Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-ferroelectric Liquid Crystal Display). ), STN (Super Twisted Nematic), HAN (Hybrid Aligned Nematic) and the like can be used.

(Back side polarizing plate and front side polarizing plate)
The back surface side polarizing plate 22 and the front surface side polarizing plate 23 are composed of a polarizing element such as an iodine-based polarizing element, a dye-based polarizing element, and a polyene-based polarizing element, and a pair of transparent protective films arranged on both sides thereof. Further, the transmission axes of the back surface side polarizing plate 22 and the front surface side polarizing plate 23 are orthogonal to each other, and in a plan view, the transmission axis of the back surface side polarizing plate 22 has an intersection angle with the ridge line direction of the prism array 42 of the turning film 4 of 45. The transmission axis of the surface-side polarizing plate 23 has an intersection angle with the ridgeline direction of the prism array 42 of the turning film 4 of 135 degrees. The transmission axis direction of the back surface side polarizing plate 22 and the transmission axis direction of the front surface side polarizing plate 23 may be interchanged.

<Light guide film>
The light guide film 3 emits light rays incident from the end face substantially uniformly from the surface. The light guide film 3 is formed in a substantially rectangular shape in a plan view, and is formed in a plate shape (non-wedge shape) having a substantially uniform thickness. The light guide film 3 is not particularly limited, but has a plurality of recesses recessed on the front surface side on the back surface (not shown). The plurality of recesses function as a light scattering portion that scatters the incident light toward the surface side. The light scattering portion is not limited to a plurality of concave portions, and may be, for example, a plurality of convex portions, or may have a convex or concave prism array shape.

The main components of the light guide film 3 are polycarbonate, acrylic resin, polyethylene terephthalate, polyethylene naphthalate, polystyrene, methyl (meth) acrylate-styrene copolymer, polyolefin, cycloolefin polymer, cycloolefin copolymer, cellulose acetate, and weather resistance. Examples thereof include sex vinyl chloride and active energy ray-curable resins. Among them, polycarbonate or acrylic resin is preferable as the main component of the light guide film 3. Since polycarbonate has excellent transparency and a high refractive index, the light guide film 3 contains polycarbonate as a main component, so that total reflection is likely to occur on the front and back surfaces of the light guide film 3, and light rays can be efficiently propagated. can. Further, since polycarbonate has heat resistance, deterioration due to heat generation of the LED light source 5 is unlikely to occur. Furthermore, since polycarbonate has less water absorption than acrylic resin or the like, it has high dimensional stability. Therefore, the light guide film 3 can suppress deterioration over time by containing polycarbonate as a main component. On the other hand, since the acrylic resin has high transparency, it is possible to reduce the wear of light in the light guide film 3.

<Turning film>
The turning film 4 is disposed on the substrate layer 41 made of a transparent resin, the prism array 42 disposed on the back surface side of the substrate layer 41, and the front surface side of the substrate layer 41 to diffuse transmitted light rays. It has a diffusion layer 43. The turning film 4 is formed in a substantially rectangular shape in a plan view, and emits light rays incident from the back surface side from the front surface side.

(Base layer)
The base material layer 41 contains polycarbonate as a main component from the viewpoint of transparency and heat resistance. The base material layer 41 is formed in a plate shape having a substantially uniform thickness. The retardation value of the base material layer 41 is adjusted so as to substantially match the half wavelength of visible light (light having a wavelength defined by JIS-Z8120 of 360 nm or more and 830 nm or less). That is, the retardation value of the base material layer 41 is adjusted to be 180 nm or more and 415 nm or less, and the variation of the in-plane retardation value is 50 nm or less. Further, the slow axis of the base material layer 41 divides the intersection angle between the transmission axis of the back surface side polarizing plate 22 and the direction perpendicular to the ridge line of the prism array 42 into two in a plan view. Specifically, the slow axis of the base material layer 41 has an intersection angle with the transmission axis of the back surface side polarizing plate 22 of the liquid crystal panel 2 of 45 degrees in a plan view, and is in a direction perpendicular to the ridgeline of the prism array 42. The angle of intersection is 22.5 degrees. That is, in the base material layer 41, the slow phase axis and the retardation value are adjusted so that the vibration direction of the light emitted from the turning film 4 after entering the turning film 4 coincides with the transmission axis of the back surface side polarizing plate 22. ing.

(Prism array)
The prism array 42 is arranged on the back surface side of the base material layer 41 and has a plurality of prisms having a triangular columnar shape. The ridgeline direction of the prism array 42 is parallel to the end surface of the light guide film 3 on the side where the LED light source 5 is arranged in a plan view. That is, in a plan view, the angle of intersection of the transmission axis of the back surface side polarizing plate 22 of the liquid crystal panel 2 with the end surface of the light guide film 3 on the side where the LED light source 5 is arranged is 45 degrees. Further, the prism array 42 is an ultraviolet curable resin molded product, and is molded by using, for example, an acrylic ultraviolet curable resin having a high transmittance. The refractive index of the prism array 42 is 1.35 or more and 1.70 or less, and the difference in refractive index between the prism array 42 and the base material layer 41 is 0.01 or more and 0.25 or less in absolute value.

The prisms constituting the prism array 42 are formed in a continuous triangular columnar shape from one side end to the other side end of the turning film 4, and the tops of the prisms form substantially parallel ridge lines. The prism has a substantially isosceles triangular shape whose cross section perpendicular to the ridgeline (cross section shown in FIG. 1) has a base shorter than the hypotenuse, and is connected to the back surface side of the base material layer 41 at the bottom. That is, the prisms constituting the prism array 42 have an acute angle on the back surface side. The prism array 42 is preferably configured to have elasticity in order to prevent scratches on the light guide films 3 that are superimposed on each other. Further, it is preferable that the slope of each prism is designed to have a shape such as a convex arc or a concave arc according to the light emission characteristics from the light guide film 3.

The prism array 42 is not limited to a configuration in which the prism is directly connected to the back surface side of the base material layer 41, and includes a transparent prism base material layer and a prism arranged on the prism base material layer. However, the prism may be connected to the back surface side of the base material layer 41 via the prism base material layer.

(Diffusion layer)
The diffusion layer 43 is arranged on the surface side of the base material layer 41 and diffuses transmitted light rays. The diffusion layer 43 is provided by forming an uneven shape on the surface side of the base material layer 41. The diffusion layer 43 diffuses the light rays transmitted from the back surface side to the front surface side substantially uniformly due to the uneven shape, and suppresses the glare of the emitted light. The uneven shape of the diffusion layer 43 is formed by, for example, embossing, diffusion coating, sandblasting, or the like. In particular, from the viewpoint of preventing interference with the pixel pitch of the liquid crystal panel 2, it is preferable that the diffusion layer 43 is formed by a diffusion coat.

<LED light source>
One or a plurality of LED light sources 5 are arranged along the end face of the light guide film 3. Each of the LED light sources 5 is arranged so that the light emitting surface faces (or abuts) the end surface of the light guide film 3.

(advantage)
Since the liquid crystal display device 1 includes a turning film 4 having a base material layer 41 containing polycarbonate as a main component and a prism array 42 whose retardation value is controlled, the vibration direction of the light emitted from the turning film 4 can be controlled. .. Further, in the liquid crystal display device 1, in a plan view, the transmission axis of the back surface side polarizing plate 22 of the liquid crystal panel 2 has an intersection angle with the ridgeline direction of the prism array 42 of the turning film 4 at 45 degrees, and the prism array 42 of the turning film 4 has a crossing angle of 45 degrees. The ridgeline direction of the light guide film 3 is parallel to the end surface of the light guide film 3, and the slow axis of the substrate layer 41 of the turning film 4 has an intersection angle with the transmission axis of the backside polarizing plate 22 of the liquid crystal panel 2 of 22.5 degrees. Therefore, by aligning the vibration direction of the light emitted from the turning film 4 with the transmission axis of the back surface side polarizing plate 22 of the liquid crystal panel 2, it is possible to reduce the loss of light and suppress the color unevenness and the variation in brightness due to the polarization.

Further, in the liquid crystal display device 1, since the prism constituting the prism array 42 has an acute angle on the back surface side, the shape of the slope of the prism can be selected according to the light emission characteristics from the light guide film 3.

Further, in the liquid crystal display device 1, the refractive index of the prism array 42 is 1.35 or more and 1.70 or less, and the refractive index difference between the prism array 42 and the base material layer 41 is 0.01 or more and 0.25 or less. Therefore, it is possible to appropriately control the light input characteristics to the base material layer 41.

Further, in the liquid crystal display device 1, since the prism array 42 has elasticity, it is possible to prevent the light guide film 3 from being scratched by the prism array 42 coming into contact with the light guide film 3.

Further, in the liquid crystal display device 1, since the prism array 42 is a molded product of an ultraviolet curable resin, it is relatively easy to use the ultraviolet curable resin when arranging the prism array 42 on the base material layer 41 to make a turning film. 4 can be manufactured.

[Second Embodiment]
[Liquid crystal display device]
The liquid crystal display device 11 of FIG. 2 includes a liquid crystal panel 2, a light guide plate (light guide film 3) that is superimposed on the back surface side of the liquid crystal panel 2 and guides light rays incident from the end surface to the front surface side, and the light guide film 3. It includes one or a plurality of LED light sources 5 arranged along the end surface of the liquid crystal panel 2 and a turning film 4 superimposed between the liquid crystal panel 2 and the light guide film 3. Further, the liquid crystal display device 11 includes a bonding layer 6 disposed between the liquid crystal panel 2 and the turning film 4. The liquid crystal display device 11 can have the same configuration as the liquid crystal display device 1 of FIG. 1 except that the liquid crystal display device 11 includes the bonding layer 6. Therefore, only the bonding layer 6 will be described below.

(Joining layer)
The joining layer 6 joins the turning film 4 and another member laminated on the surface side of the turning film 4. More specifically, the bonding layer 6 bonds the turning film 4 and the back surface side polarizing plate 22 disposed on the back surface of the liquid crystal cell 21. The bonding layer 6 is an adhesive layer composed of an adhesive or a pressure-sensitive adhesive layer composed of an adhesive.

When the bonding layer 6 is the above-mentioned adhesive layer, examples of the adhesive constituting the adhesive layer include a heat-curable adhesive, a hot-melt adhesive, a photo-curable adhesive, and the like. Examples of the thermosetting adhesive include acrylic adhesives, epoxy adhesives, urethane adhesives and the like. Examples of the hot melt adhesive include ethylene-vinyl acetate copolymer (EVA) -based adhesives, polyester-based adhesives, polyamide-based adhesives, thermoplastic polyurethane-based adhesives, and polyolefin-based adhesives. Examples of the photocurable adhesive include an acrylic ultraviolet curable adhesive, an acrylic urethane ultraviolet curable adhesive, and an epoxy ultraviolet curable adhesive. Among them, an acrylic adhesive or an acrylic urethane adhesive having excellent heat resistance, moisture resistance and the like is preferable, and an acrylic adhesive having a high transmittance is particularly preferable. The refractive index of the adhesive is preferably adjusted so as to reduce light loss due to light scattering and light reflection at the interface between the bonding layer 6 and other members bonded to the bonding layer 6. For example, when the main component of the outermost surface layer of the turning film 4 is polycarbonate, the refractive index of the adhesive is preferably 1.47 or more and 1.55 or less.

On the other hand, when the bonding layer 6 is the above-mentioned pressure-sensitive adhesive layer, the bonding layer 6 has tackiness. When the bonding layer 6 is the above-mentioned pressure-sensitive adhesive layer, examples of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer include pressure-sensitive adhesives having adhesive strength at room temperature. Examples of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer include an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and an epoxy-based pressure-sensitive adhesive.

Since the liquid crystal display device 11 includes a bonding layer 6 for bonding the turning film 4 and another member (back surface side polarizing plate 22 in the present embodiment) laminated on the front surface side of the turning film 4, the turning film 4 is provided. And the handleability of the above-mentioned other members can be improved.

[Other embodiments]
It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is not limited to the configuration of the above embodiment, but is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims. To.

In the above embodiment, in a plan view, the transmission axis of the backside polarizing plate 22 of the liquid crystal panel 2 intersects the ridgeline direction of the prism array 42 of the turning film 4 at 45 degrees, and the slow phase of the substrate layer 41 of the turning film 4 is set. The case where the axis has an intersection angle with the transmission axis of the back surface side polarizing plate 22 of the liquid crystal panel 2 is 22.5 degrees has been described. However, in a plan view, the intersection angle between the slow axis of the substrate layer 41 of the turning film 4 and the transmission axis of the back surface side polarizing plate 22 of the liquid crystal panel 2 is turning with the transmission axis of the back surface side polarizing plate 22 of the liquid crystal panel 2. Half of the angle of intersection with the direction perpendicular to the ridgeline of the prism array 42 of the film 4, in other words, the angle of intersection between the transmission axis of the backside polarizing plate 22 of the liquid crystal panel 2 and the ridgeline direction of the prism array 42 of the turning film 4 is α. In this case, if the crossing angle β between the slow axis of the substrate layer 41 of the turning film 4 and the transmission axis of the backside polarizing plate 22 of the liquid crystal panel 2 is (45-α / 2) degrees, the above embodiment is used. Not limited. For example, when the crossing angle α is 60 degrees, the crossing angle β may be 15 degrees, and when the crossing angle α is 30 degrees, the crossing angle β may be 30 degrees.

That is, in the liquid crystal display device 1, in a plan view, the transmission axis of the back surface side polarizing plate 22 of the liquid crystal panel 2 has an intersection α with the ridgeline direction of the prism array 42 of the turning film 4 of 0 degrees or more and less than 90 degrees, and the turning film. It suffices that the slow axis of the base material layer 41 of 4 has an intersection angle with the transmission axis of the back surface side polarizing plate 22 of the liquid crystal panel 2 at (45-α / 2) degrees. Further, the turning film 4 may be such that the slow axis of the base material layer 41 has an intersection angle with the ridgeline direction of the prism array 42 of 45 degrees or more and less than 90 degrees in a plan view.

Further, the crossing angle α may be 0 degrees. That is, in the liquid crystal display device 1, the transmission axis of the back surface side polarizing plate 22 of the liquid crystal panel 2 is parallel to the ridgeline direction of the prism array 42 of the turning film 4, and the slow phase of the substrate layer 41 of the turning film 4 is parallel to the liquid crystal display device 1. The axis may have an angle of intersection with the transmission axis of the back surface side polarizing plate 22 of the liquid crystal panel 2 of 45 degrees.

In the above embodiment, the one using the light guide film 3 as the light guide plate has been described, but the light guide plate is not limited to the film-like one. For example, the light guide plate may be a plate-shaped light guide plate.

Further, the light guide plate may be configured to have either a prism array or a lenticular lens array arranged on the surface side. In this case, the liquid crystal display device 1 may have the ridgeline direction of the surface of the light guide plate perpendicular to the ridgeline direction of the prism array 42 of the turning film 4 in a plan view. When the light guide plate is configured to have either a prism array or a lenticular lens array arranged on the surface side, the optical performance such as the viewing angle of the liquid crystal display device 1 is improved.

In the above embodiment, the turning film 4 has a diffusion layer 43 arranged on the surface side of the base material layer 41, but the turning film 4 may not have the diffusion layer 43. Further, the turning film 4 may have at least one of a microlens array or a reflective polarizing plate in place of the diffusion layer 43 or in addition to the diffusion layer 43.

When the turning film has a reflective polarizing plate on the surface side of the substrate layer, the substrate layer and the reflective polarizing plate may be bonded by a bonding layer composed of the above-mentioned adhesive or pressure-sensitive adhesive. Further, the turning film may have a bonding layer on the surface side of the base material layer, and a reflective polarizing plate may be arranged as another member on the surface side of the bonding layer. When the turning film has a bonding layer on the surface side of the base material layer, the turning film may have a release sheet on the surface of the bonding layer.

The liquid crystal display device and the turning film of the present invention can suppress color unevenness and brightness variation due to polarization.

1 Liquid crystal display 2 Liquid crystal panel 3 Light guide film 4 Turning film 5 LED light source 6 Bonding layer 11 Liquid crystal display 21 Liquid crystal cell 22 Back side polarizing plate 23 Front side polarizing plate 41 Base material layer 42 Prism array 43 Diffusion layer

Claims (8)

LCD panel and
A light guide plate that is superimposed on the back surface side of this liquid crystal panel and guides the light rays incident from the end surface to the front surface side.
One or more LED light sources arranged along the end face of the light guide plate, and
A liquid crystal display device including a turning film superimposed between the liquid crystal panel and the light guide plate.
The above turning film
A base layer made of transparent resin and
It has a prism array arranged on the back surface side of this base material layer, and has.
The above LCD panel
LCD cell and
It has a back side polarizing plate arranged on the back side of this liquid crystal cell, and has.
The retardation value of the base material layer of the turning film is 180 nm or more and 415 nm or less.
The main component of the base material layer is polycarbonate, and the variation in the in-plane retardation value of the base material layer is 50 nm or less.
The refractive index of the prism array is 1.35 or more and 1.70 or less.
The difference in refractive index between the prism array and the base material layer is 0.01 or more and 0.25 or less.
In a plan view, the transmission axis of the polarizing plate on the back surface side of the liquid crystal panel has an angle α of 0 degrees or more and less than 90 degrees with the ridgeline direction of the prism array of the turning film, and the ridgeline direction of the prism array of the turning film is the light guide plate. The slow axis of the base material layer of the turning film, which is parallel to the end face of the above, is characterized in that the angle of intersection with the transmission axis of the polarizing plate on the back surface side of the liquid crystal panel is (45-α / 2) degrees. Liquid crystal display device. The liquid crystal display device according to claim 1, wherein the prism array is made of acrylic resin. The liquid crystal display device according to claim 1 or 2, wherein the turning film has at least one of a diffusion layer, a microlens array, and a reflective polarizing plate arranged on the surface side of the base material layer. The liquid crystal display device according to claim 1, claim 2 or claim 3, wherein the prism constituting the prism array has an acute angle on the back surface side. The liquid crystal display device according to any one of claims 1 to 4 , wherein the prism array has elasticity. The liquid crystal display device according to any one of claims 1 to 5 , wherein the prism array is an ultraviolet curable resin molded product. The light guide plate has either a prism array or a lenticular lens array arranged on the surface side.
The liquid crystal display device according to any one of claims 1 to 6 , wherein the ridgeline direction of the surface of the light guide plate is perpendicular to the ridgeline direction of the prism array of the turning film in a plan view. It includes a liquid crystal panel, a light guide plate superimposed on the back surface side of the liquid crystal panel and guiding light rays incident from the end surface to the front surface side, and one or a plurality of LED light sources arranged along the end surface of the light guide plate. A turning film superimposed between the liquid crystal panel and the light guide plate in a liquid crystal display device.
A base material layer containing polycarbonate as the main component and
A prism array arranged on the back surface side of this base material layer,
It is arranged on the surface side of the base material layer and has a diffusion layer that diffuses transmitted light rays.
The refractive index of the prism array is 1.35 or more and 1.70 or less.
The difference in refractive index between the prism array and the base material layer is 0.01 or more and 0.25 or less.
The retardation value of the base material layer is 180 nm or more and 415 nm or less, and the variation of the in-plane retardation value is 50 nm or less.
A turning film for a liquid crystal display device, wherein the slow axis of the base material layer has an intersection angle with the ridgeline direction of the prism array of the turning film of 45 degrees or more and less than 90 degrees in a plan view.

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