JP2009294468A - Video display device and optical sheet - Google Patents

Abstract

An image display device capable of suppressing unevenness in an image regardless of the environment is provided.
An image display device 1 for emitting an image from an image source to an observer, the image sources 11 and 13 emitting an image by self-light emission or being combined with a light source, and an observer side from the image source And an optical sheet having a plurality of layers for controlling the light from the image source and emitting the light to the viewer side, and at least one of the plurality of layers includes: It has a prism part 18 formed of a material having a predetermined glass transition point, which is arranged in parallel along the sheet surface so as to transmit light, and a light absorption part 19 arranged in parallel so as to be able to absorb light between the prism parts. The optical function sheet layer 17 is characterized in that the glass transition point of the prism portion is higher than the temperature reached by the optical function sheet layer when an image is emitted from the image source unit.
[Selection] Figure 1

Description

  The present invention relates to an image display device and an optical sheet that emit an image from an image source to an observer, and more particularly to an image display device and an optical sheet that can reduce unevenness of image light.

  For video display devices that emit images to the viewer, such as liquid crystal displays, plasma displays, rear projections, organic ELs, FEDs, etc., the video source and the quality of the video light from the video source can be improved for the viewer. And an optical sheet having layers having various functions for emission.

As such an optical sheet, for example, Patent Document 1 is disclosed. The optical sheet described in Patent Document 1 is disposed between prism portions that transmit image light and between the prism portions, and appropriately blocks or reflects image light and external light to improve contrast or suppress ghosts. Light absorption part.
JP 2006-189867 A

  However, when an optical sheet described in Patent Document 1 and a conventional optical sheet are used for a display device and the display device is operated, there is a case where unevenness occurs in an image.

  In view of the above problems, an object of the present invention is to provide an image display device and an optical sheet that can suppress unevenness in an image regardless of the environment.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiments.

  As a result of intensive studies, the inventors have obtained knowledge that the above-described image unevenness is caused by the temperature reached by the image source unit when the image is emitted. Based on this knowledge, the inventors have completed the following invention.

  The invention described in claim 1 is an image display device (1, 2, 3, 4, 39, 50, 60) for emitting an image from an image source to an observer, and is self-luminous or combined with a light source. And an optical sheet having a plurality of layers arranged on the viewer side from the video source and controlling the light from the video source to emit to the viewer side And at least one of a plurality of layers formed of a material having a predetermined glass transition point arranged in parallel along the sheet surface so as to transmit light. Prism units (18, 26, 28, 31, 44, 52, 62) and light absorption units (19, 29a, 29b, 32a, 32b, 45, 53a) arranged in parallel to be able to absorb light between the prism units. 53b, 63a, 63b) Glass layer (17, 25, 27, 30, 43, 51, 61), and the glass transition point of the prism portion is higher than the temperature reached by the optical function sheet layer when the image is emitted from the image source unit. The problem is solved by providing a video display device characterized by high image quality.

  Here, “the prism parts are juxtaposed along the sheet surface” means that the prism parts are not limited to be juxtaposed along one direction of the sheet surface, and have a predetermined law property along the sheet surface. It is a good concept if they are arranged so as to be arranged. Therefore, for example, they may be arranged obliquely along the sheet surface, or may be arranged in a staggered manner.

  According to a second aspect of the present invention, in the video display device (1, 2, 3, 4, 39, 50, 60) of the first aspect, the prism portion (18, 26, 28, 31, 44, 52, 62) the glass transition point is 56 ° C. or higher and 120 ° C. or lower.

  According to a third aspect of the present invention, in the video display device (1, 2, 3, 4, 39, 50, 60) according to the first or second aspect, the prism portion (18, 26, 28, 31, 44, 52, 62) is characterized by being an ultraviolet curable resin.

  According to a fourth aspect of the present invention, in the video display device (1, 2, 3, 4, 39, 50, 60) according to any one of the first to third aspects, the light absorbing portion (19, 29a, 29b, 32a, 32b, 45, 53a, 53b, 63a, 63b) are filled with a binder (20) made of resin and light-absorbing particles (21) having an average particle diameter of 1 μm or more are dispersed. It is characterized by that.

  Here, “average particle size of 1 μm” in the case of “average particle size of 1 μm or more” is intended for particles having a particle size of 0.5 μm or more and smaller than 1.5 μm in the particle size measurement by the weight distribution method. In the particle size distribution, it means that the standard deviation is 0.3 or more. The same applies hereinafter.

  The invention according to claim 5 is the prism portion (18, 26) and the light absorption portion of the optical function sheet layer (17, 25) of the video display device (2) according to any one of claims 1-4. (19) is formed extending in the longitudinal direction while maintaining a predetermined cross section, and two optical function sheet layers are laminated, and one of the two optical function sheet layers is an optical function sheet layer The light absorbing portion is laminated such that the longitudinal direction of the light absorbing portion and the longitudinal direction of the light absorbing portion of the other optical functional sheet layer of the two optical functional sheet layers have a predetermined angle.

  The invention described in claim 6 is characterized in that the predetermined angle of the video display device (2) according to claim 5 is 90 degrees.

  The invention according to claim 7 is the light of the optical function sheet layer (27, 30, 51, 61) of the video display device (3, 4, 50, 60) according to any one of claims 1-4. The absorption parts (29a, 29b, 32a, 32b, 53a, 53b, 63a, 63b) are formed in a lattice shape that intersects at a predetermined angle.

  The invention described in claim 8 is characterized in that the predetermined angle of the video display device (3, 50) according to claim 7 is 90 degrees.

  According to a ninth aspect of the present invention, in the video display device (12, 3, 4) according to any one of the first to eighth aspects, the video source unit further includes an anti-glare film layer (24) from the observer side. The TAC film layer (23) and the pressure-sensitive adhesive layer (22) are provided in this order.

  The invention according to claim 10 is an optical sheet (10b, 40b) used in the video display device (1, 2, 3, 4, 39, 50, 60) according to any one of claims 1-9. A plurality of layers arranged on the viewer side from the video source, controlling light from the video source and emitting to the viewer side, at least one of the plurality of layers transmitting light A prism portion (18, 26, 28, 31, 44, 52, 62) formed of a material that is juxtaposed along the sheet surface and has a glass transition point of 56 ° C. or more and 120 ° C. or less, and between the prism portions And an optical function sheet layer (17, 25, 27, 30, 43) having light absorbing portions (19, 29a, 29b, 32a, 32b, 45, 53a, 53b, 63a, 63b) arranged in parallel to absorb light. 51, 61). Up by solving the problems.

  The invention according to claim 11 is an optical sheet (10b, 40b) comprising a plurality of layers, wherein at least one of the plurality of layers is juxtaposed along the sheet surface so as to transmit light, and is made of glass. A prism portion (18, 26, 28, 31, 44, 52, 62) formed of an ultraviolet curable resin having a transition point of 56 ° C. or higher and 120 ° C. or lower, and light that is arranged in parallel so that light can be absorbed between the prism portions. And an optical function sheet layer (17, 25, 27, 30, 43, 51, 61) having an absorption part (19, 29a, 29b, 32a, 32b, 45, 53a, 53b, 63a, 63b). The above-mentioned problem is solved by the characteristic optical sheet.

  According to a twelfth aspect of the present invention, the light absorbing portion (19, 29a, 29b, 32a, 32b, 45, 53a, 53b, 63a, 63b) of the optical sheet according to the eleventh aspect has a binder ( 20) and light-absorbing particles (21) having an average particle diameter of 1 μm or more are dispersed.

  According to a thirteenth aspect of the present invention, the prism portion (18, 26) and the light absorbing portion (19) of the optical function sheet layer (17, 25) of the optical sheet according to the eleventh or twelfth aspect maintain a predetermined cross section. And extending in the longitudinal direction, two optical functional sheet layers are laminated, and the longitudinal direction of the light absorbing portion of one optical functional sheet layer of the two optical functional sheet layers, The two optical function sheet layers are laminated so that the longitudinal direction of the light absorbing portion of the other optical function sheet layer has a predetermined angle.

  The invention according to claim 14 is characterized in that the predetermined angle of the optical sheet according to claim 13 is 90 degrees.

  The invention according to claim 15 is the light absorbing portion (29a, 29b, 32a, 32b, 53a, 53b) of the optical function sheet layer (27, 30, 51, 61) of the optical sheet according to claim 11 or 12. 63a, 63b) are formed in a lattice shape that intersects at a predetermined angle.

  The invention described in claim 16 is characterized in that the predetermined angle of the optical sheet described in claim 15 is 90 degrees.

  The image display device and the optical sheet of the present invention can suppress the occurrence of image unevenness regardless of the environment.

  Such an operation and gain of the present invention will be made clear from the best mode for carrying out the invention described below.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings. However, the present invention is not limited to these embodiments.

  FIG. 1 is a diagram schematically showing a layer configuration of a cross section of a video source unit 10 included in the video display device 1 according to the first embodiment. In FIG. 1, the right side of the page is the observer side. The video display device 1 of the present embodiment is a liquid crystal display device, and the video source unit 10 is a liquid crystal display panel unit. In the figures shown below, some repetitive symbols may be omitted for ease of viewing.

  The image source unit 10 includes a backlight 11, a polarizing plate 12, a liquid crystal panel 13, a polarizing plate 14, an adhesive layer 15, a PET film layer 16, an optical function sheet layer 17, an adhesive layer 22, a TAC film layer 23, and an antiglare. A film layer (AG layer) 24 is provided. Among these, the pressure-sensitive adhesive layer 15, the PET film layer 16, the optical function sheet layer 17, the pressure-sensitive adhesive layer 22, the TAC film layer 23, and the AG layer 24 are formed in advance as the optical sheet 10 b, and the backlight 11 and the polarizing plate 12. 14 and the liquid crystal panel 13 are attached to the video source 10a. Each of the layers extends in the back / front direction of the paper while maintaining the cross section shown in FIG. Each layer will be described below. Further, the video display device 1 is provided with an electric circuit, a power circuit, and the like for operating the video source unit 10.

  The backlight 11 is a light source of the liquid crystal panel 13. Here, a backlight used in a normal liquid crystal display panel unit can be used. This includes, for example, a form in which light emitting sources are arranged substantially uniformly in a plane to form a planar light source, or a light emitting source is arranged on an edge and a reflecting surface is used to finally form a planar shape. Examples include an edge input type that emits light. In any case, since the backlight 11 generates heat, the temperature of the image source unit 10 is increased and temperature unevenness is caused. The relationship between the temperature unevenness and the effect of the present invention will be described later.

  The polarizing plates 12 and 14 are a pair of optical elements arranged so as to sandwich the liquid crystal panel 13, and absorb polarized light having a vibration surface parallel to the absorption axis direction, while having a vibration surface orthogonal to the absorption axis direction. It has a function of transmitting the polarized light. The light of the backlight 11 that has passed through the polarizing plates 12 and 14 and the liquid crystal panel 13 becomes image light and is emitted to the viewer side.

  The liquid crystal panel 13 is one of the elements constituting the video source 10a in the video source unit 10, and video information to be emitted is shown here. The liquid crystal panel used for a normal liquid crystal display panel unit can be used here. Accordingly, in the video source unit 10, the video source 10 a is formed by the backlight 11, the polarizing plates 12 and 14, and the liquid crystal panel 13.

  The pressure-sensitive adhesive layers 15 and 22 are layers arranged so as to sandwich the PET film layer 16 and the optical function sheet layer 17, and are used to bond the PET film layer 16 and the optical function sheet layer 17 to other layers. Is a layer in which is arranged. The material of the pressure-sensitive adhesive used for the pressure-sensitive adhesive layers 15 and 22 is not particularly limited as long as it transmits light and can appropriately bond the PET film layer 16 and the optical function sheet layer 17 to each other. For example, PSA (pressure sensitive adhesive) can be used. The adhesive strength is, for example, about several N / 25 mm to 20 N / 25 mm.

  The PET film layer 16 is a film layer as a base material layer serving as a base for forming the optical functional sheet layer 17 on one surface of the PET film layer 16, and is formed mainly of PET. The PET film layer 16 only needs to contain PET as a main component, and may contain other resins. Here, the main component means 50% by mass or more based on the whole PET film layer. Various additives may be added. Examples of general additives include phenol-based antioxidants, lactone-based stabilizers, and the like.

  Here, the PET film layer has been described as the base material layer, but the material is not necessarily made of PET, and other than the above, “polyester resin such as polybutylene terephthalate resin (PBT) or polytrimethylene terephthalate (PTT) resin. Can be used. In the present embodiment, it has been described that a resin having PET as a main component is a preferable material from the viewpoint of mass productivity, price, availability, etc. in addition to performance.

  The optical functional sheet layer 17 includes prism portions 18, 18,... That are substantially trapezoidal in the cross section in the thickness direction of the sheet, and light absorbing portions 19, 19,... Disposed between the prism portions 18, 18,. It has. FIG. 2 shows an enlarged view focusing on the two light absorbing portions 19 and 19 and the prism portions 18, 18 and 18 adjacent thereto. The optical function sheet layer 17 will be described with reference to FIGS. 1 and 2.

  The prism portions 18, 18,... Are elements having a substantially trapezoidal cross section arranged such that the PET film layer 16 side is the lower base and the other side is the upper base. The prism portions 18, 18,... Are made of a light transmissive resin having a refractive index of Np. This is usually formed of, for example, epoxy acrylate, urethane acrylate or the like having a characteristic of being cured by ionizing radiation, ultraviolet rays, or the like. The size of Np is not particularly limited, but is preferably 1.49 to 1.56 from the viewpoint of availability of applicable materials. The image light is provided to the observer by transmitting the image light through the prism portions 18, 18,.

  Further, the prism portions 18, 18,... Have a predetermined glass transition point (hereinafter sometimes referred to as “Tg”). Here, the predetermined Tg is a value (temperature) higher than the maximum temperature reached by the optical function sheet layer 17 when the video display device 1 is operated. Specifically, it is preferably 56 ° C. or higher from the viewpoint of the reached temperature assumed in a normal video display device. Moreover, it is preferable that it is 120 degrees C or less from a viewpoint of the availability of such a material and the generation | occurrence | production of the crack by Tg becoming high too much. The relationship between the temperature reached by the video source unit 10 and the unevenness generated in the video will be described later.

  Here, in order to set Tg to a predetermined value, it is possible to change the composition ratio of epoxy acrylate, urethane acrylate, etc., which are materials constituting the prism portion, or to adjust the molecular weight thereof.

  The light absorbing portions 19, 19,... Are portions disposed between the prism portions 18, 18,. The light absorbing portions 19, 19,... Have a substantially triangular shape with the upper base side of the prism portions 18, 18,... As the base, and the apex opposite thereto is the lower base side of the prism portions 18, 18,. . The light absorbing parts 19, 19,... Are binder parts 20, 20,... Filled with a substance having a refractive index of Nb, and light absorbing particles 21, 21, mixed in the binder parts 20, 20,. … And. When external light is incident on and absorbed by the light absorbing portions 19, 19,..., The influence of the external light on the image light can be reduced, and the contrast can be improved.

  The binder material filled in the binder portions 20, 20,... Is made of a material having a refractive index Nb. Although the magnitude | size of Nb is not specifically limited, From a viewpoint of the availability of the material to apply, it is preferable that it is 1.49-1.56. The material used as the binder material is not particularly limited, and examples thereof include urethane acrylate having characteristics of being cured by ionizing radiation, ultraviolet rays, and the like. Here, the Tg of the material used for the binder parts 20, 20,... Is not particularly limited, but preferably has a Tg equal to or higher than the Tg of the prism parts 18, 18,.

  Here, the difference between the refractive index Np of the prism portions 18, 18,... And the refractive index Nb of the binder portions 20, 20,... Is preferably greater than 0 and not greater than 0.10. As a result, total reflection is appropriately performed at the interface between the prism portions 18, 18,... And the light absorbing portions 19, 19,..., And stray light or outside light is incident on the light absorbing portions 19, 19,. be able to.

  The light-absorbing particles 21, 21,... Are preferably particles having an average particle size of 1 μm or more from the viewpoint of availability and production. This is a particle such as carbon or a dye such as red, blue, yellow or black. It is colored in concentration. For this, for example, commercially available colored resin particles can be used. The refractive index Nr of the light absorbing particles 21, 21,... Is not particularly limited.

  Here, the light absorption performance of the light absorbing portions 19, 19,... Can be adjusted as appropriate depending on the purpose. However, in the transmittance measurement of a sheet having a thickness of 6 μm formed only of the material constituting the light absorbing portion, It is preferable that the light absorption performance is such that the rate is 40 to 70%. The means for adjusting the transmittance to 40 to 70% is not particularly limited, and examples thereof include adjusting the content of light absorbing particles and light absorbing performance.

  Further, the angle θ of the oblique sides (two sides extending in the sheet thickness direction) of the light absorbing portions 19, 19,... With respect to the sheet surface normal can be changed according to the purpose and is not particularly limited. However, in the case of a normal video display device, it is preferably 6 to 15 degrees from the viewpoint of appropriately reflecting and absorbing external light and video light.

  As shown in FIGS. 1 and 2, the optical function sheet layer 17 has prism portions 18, 18,... Having a substantially trapezoidal cross section, and light absorbing portions 19, 19,. It has a triangular cross section. However, if the light can be controlled appropriately, these shapes are not particularly limited, and appropriate shapes are appropriately adopted. For example, the light absorbing portion may be a trapezoidal cross section instead of a triangular cross section. Further, the hypotenuse forming the interface between the prism portion and the light absorbing portion may be a polygonal line or a curved line.

  The TAC film layer 23 is a film formed of triacetyl cellulose and is used as a protective film. As the TAC film used for the TAC film layer 23, a TAC film used for an ordinary liquid crystal display panel unit can be applied.

  The AG layer 24 is a film that can prevent glare when an observer looks at the screen. As the antiglare film, a generally available AG film can be applied. In the present embodiment, this is the AG layer, but an AR layer may be arranged instead of the AG layer. The AR layer means an “anti-reflection layer” and is a layer that can prevent reflection.

  Moreover, although Tg of these PET film layer 16, TAC film layer 23, and AG layer 24 is not specifically limited, It is preferable that it is more than Tg of above-described prism part 18, 18, ....

  The video display device 1 including the video source unit 10 as described above operates, for example, as follows. The optical path is shown in FIG. FIG. 3 is a diagram for explaining an example of the temperature distribution when the video display device 1 is viewed from the front.

  When the image display device 1 is operated, the image light L1 passes through each layer provided in the image source unit 10 and is emitted to the observer as shown in FIG. The image lights L2 and L3 are totally reflected at the interface between the prism portions 18 and 18 and the light absorbing portions 19 and 19 and are emitted to the viewer side. At this time, since the hypotenuses of the light absorbing portions 19 and 19 are inclined as described above, the angle of light changes before and after the reflection by the hypotenuse, and the image light can be emitted in the direction in which the viewing angle is widened. Thereby, a wide viewing angle can be obtained. On the other hand, the external light L4 incident on the image display device 1 as external light is incident on the light absorption unit 19 and absorbed therein. In this way, a part of the external light is absorbed by the light absorbing portions 19, 19,... And the contrast can be improved.

  Thus, when the video display device is operating, a temperature distribution is generated in the video source unit 10. For example, in the portion indicated by A in FIG. 3, the temperature is T1, and in the portion indicated by B, the temperature is T2 (T1> T2). There are several possible causes of such a temperature distribution, and examples thereof include those caused by heat generation of the backlight 11 and those caused by heat generation of an electric circuit and a power supply circuit provided.

  Here, in the prism portion of the optical function sheet layer provided in the image source unit in a certain image display device, when the Tg is T2 <Tg <T1, the transmittance and the haze value are changed in the region where Tg <T1. As a result, unevenness occurs in the video light in the video source unit (screen) of the video display device. Here, the haze value indicates the ratio of diffusely transmitted light to total transmitted light. Such a change is presumed to be due to the promotion of moisture absorption when the temperature of the prism portion reaches a temperature exceeding Tg.

  On the other hand, in the video display apparatus 1, since the prism portions 18, 18,... Have a Tg higher than the maximum temperature reached by the video source unit, T2 <T1 <Tg is always satisfied, and the temperature as described above. Even if the distribution occurs, the transmittance and haze value change little. Accordingly, it is possible to suppress unevenness of the image light, and the image display device 1 is less likely to generate unevenness in the image light.

  FIG. 4 is a diagram schematically showing a layer structure of a cross section of a video source unit 10 ′ included in the video display device 2 according to the first modification of the video display device 1. In the image source unit 10 ′, another optical function sheet layer 25 is laminated between the optical function sheet layer 17 and the adhesive layer 22 of the image source unit 10 described above. The optical function sheet layer 25 has the same configuration as that of the optical function sheet layer 17, but the light absorbing portion of the optical function sheet layer 25 (only the prism portion 26 appears in FIG. 4 and the light absorbing portion appears). Is arranged in a direction orthogonal to the light absorbing portions 19, 19,... Of the optical function sheet layer 17. As a result, the direction in which the image light is diffused is expanded, and the light can be diffused in a wider range.

  FIG. 5 is a perspective view schematically showing the configuration of the optical function sheet layer 27 of the video source unit in the video display device 3 according to the second modification. In FIG. 5, cross-sectional views are respectively shown on the upper and right sides of the perspective view for easy understanding. Since the configuration other than the optical function sheet layer 27 is the same as the configuration of the video display device 1 and the video source unit 10 described above, the description thereof is omitted here. In the perspective view of FIG. 5, the front side of the paper is the observer side, and the back of the paper is the light source side.

  In the optical function sheet layer 27 shown in FIG. 5, light absorbing portions 29a, 29a,..., 29b, 29b,... Having a triangular cross section are formed in a lattice shape, and each region surrounded by the lattice is a prism portion 28, 28 ...

  Here, the light absorbing portions 29a, 29a,..., 29b, 29b,... Have a triangular cross section, but this may be a trapezoid. At this time, the trapezoidal short upper base is disposed on the light source side, and the trapezoidal long lower base is disposed on the observer side.

  In the second modification example, the light absorbing portions are formed in a lattice shape in one optical function sheet layer 27 as described above. The lattice shape intersects at a substantially right angle. By forming in this way, the viewing angle can be expanded in the horizontal and vertical directions by one optical function sheet layer 27. Accordingly, it is possible to widen the viewing angle in all directions while reducing the thickness of the image source unit and the optical sheet.

  FIG. 6 is a perspective view schematically showing the configuration of the optical function sheet layer 30 of the video source unit in the video display device 4 according to the third modification. In FIG. 6, a cross-sectional view is shown on the right side of the perspective view for easy understanding. Since the configuration other than the optical function sheet layer 30 is the same as that of the video display device 1 and the video source unit 10 described above, the description thereof is omitted here. In the perspective view of FIG. 6, the front side of the paper is the observer side, and the back side of the paper is the light source side.

  In the optical function sheet layer 30 shown in FIG. 6, light absorption portions 32 a, 32 a,..., 32 b, 32 b,... Having a triangular cross section are formed in a lattice shape, and each region surrounded by the lattice is a prism portion 31. 31 and so on.

  Here, the light absorbing portions 32a, 32a,..., 32b, 32b,... Have a triangular cross section, but they may be trapezoidal. At this time, the trapezoidal short upper base is disposed on the light source side, and the trapezoidal long lower base is disposed on the observer side.

  Also in the third modified example, the light absorbing portion is formed in a lattice shape in one optical function sheet layer. The lattice shape intersects with a predetermined angle α. By forming in this way, the viewing angle characteristic to the predetermined angle corresponding to the α can be improved.

  FIG. 7 is a diagram schematically showing the layer configuration of a cross section of the video source unit 40 provided in the video display device 39 according to the second embodiment. The video display device 39 of this embodiment is a plasma display device, and the video source unit 40 is a plasma display unit.

  The video source unit 40 includes a plasma display panel 41, an adhesive layer 42, an optical function sheet layer 43, a PET film layer 46, an antistatic film (AS) layer 47, and an antiglare film (AG) layer 48. Among them, the pressure-sensitive adhesive layer 42, the optical function sheet layer 43, the PET film layer 46, the AS layer 47, and the AG layer 48 are formed in advance as an optical sheet 40b and pasted on the video source 40a that is the plasma display panel 41. Yes. Each of the above layers extends in the back / front direction of the paper while maintaining the cross section shown in FIG. Each layer will be described below. Further, the display device 39 is provided with an electric circuit, a power supply circuit, and the like for operating the video source unit 40.

  The plasma display panel 41 is a video source 40a in the video source unit 40, and video information to be emitted is shown here. The plasma display panel 41 can self-emit. The image source unit 40 can be a panel used in a normal plasma display panel unit.

  The adhesive layer 42 is a layer in which an adhesive for adhering the optical function sheet layer 43 to the plasma display panel 41 is disposed as will be described later. The material of the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer 42 is not particularly limited as long as it transmits light and can be appropriately bonded. Examples thereof include an acrylic copolymer, and the adhesive strength thereof is, for example, about several N / 25 mm to 20 N / 25 mm.

  As can be seen from FIG. 7, the optical functional sheet layer 43 has the same basic structure as the optical functional sheet layer 17 except that the orientation is different from that of the optical functional sheet layer 17 described above. However, in the video display device 39 of the present embodiment, as shown in FIG. 8 in which a part of the optical function sheet layer 43 is enlarged, the interface between the light absorbing portions 45, 45,... And the prism portions 44, 44,. The angle φ of the hypotenuse (two sides extending in the sheet thickness direction) formed by the sheet surface with respect to the normal to the sheet surface can be changed according to the purpose and is not particularly limited. From the viewpoint of reflecting and absorbing light, it is preferably greater than 0 degree and 6 degrees or less.

  Since the PET film layer 46 and the AG layer 48 are the same as those of the PET film layer 16 and the AG layer 24, the description thereof is omitted. Again, an AR layer may be provided instead of the AG layer.

  The AS layer 47 is a film that can prevent charging, that is, static electricity. A commonly available AS film can be applied to this.

  Further, the image source unit may be provided with functional film layers such as a layer for blocking electromagnetic waves, a layer for blocking infrared rays, a layer for blocking neon lines, and a layer for correcting color tone.

  The video display device 39 including the video source unit 40 as described above operates, for example, as follows. FIG. 7 shows the optical path.

  When the image display device 39 is operated, the image light L11 passes through each layer provided in the image source unit 40 and is emitted to the observer as shown in FIG. Further, the image lights L12 and L13 are totally reflected at the interface between the prism portions 44 and 44 and the light absorbing portions 45 and 45 and emitted to the viewer side. At this time, the oblique sides of the light absorbing portions 45, 45,... Have an angle different from that of the light absorbing portions 19, 19,... The image light can be emitted. Thereby, the brightness and contrast of the image light can be improved. On the other hand, the external light L14 that has entered the video display device 39 as external light is incident on the light absorbing portion 45 and absorbed therein. In this way, part of the external light is absorbed by the light absorbing portions 45, 45,..., And the contrast can be further improved.

  When the video display device is operating as described above, a temperature distribution is generated in the video source unit 40 as described in the video display device 1. There are several possible causes of the temperature distribution, and examples thereof include those caused by heat generation of the plasma display panel, and those caused by heat generation of the provided electric circuit and power supply circuit.

  However, even in this case, in the video display device 39, the prism portions 44, 44,... Have a Tg higher than the maximum temperature reached by the optical function sheet layer 43. Therefore, even if a temperature distribution occurs as described above, changes in transmittance and haze value can be suppressed to a minimum. As a result, unevenness in the image light can be suppressed. In this way, the video display device 39 can be made less likely to cause unevenness in the video light.

  FIG. 9 is a perspective view schematically showing the configuration of the optical function sheet layers 51 and 51 ′ of the video source unit in the video display devices 50 and 50 ′ according to the fourth modification. In FIG. 9, cross-sectional views are respectively shown on the upper and right sides of the perspective view for easy understanding. In the video display devices 50 and 50 ′, the configuration other than the optical function sheet layers 51 and 51 ′ is the same as that of the video display device 39 and the video source unit 40 described above, and thus the description thereof is omitted here. In the perspective view of FIG. 9, the front side of the paper is the observer side, and the back of the paper is the light source side.

  In the optical function sheet layer 51 shown in FIG. 9A, light absorbing portions 53a, 53a,..., 53b, 53b,... Having a triangular cross section are formed in a lattice shape, and each region surrounded by the lattice is a prism. The parts are 52, 52,. On the other hand, in the optical function sheet layer 51 ′ shown in FIG. 9B, the light absorbing portions 53a ′, 53a ′,..., 53b ′, 53b ′,. Each region formed and surrounded by a lattice is a prism portion 52 ′, 52 ′,.

  In the fourth modification example, the light absorbing portions are formed in a lattice shape in one optical function sheet layer 51, 51 'as described above. The lattice shape intersects at a substantially right angle. By forming in this way, the optical path can be controlled in the horizontal and vertical directions by one optical function sheet layer 27, 27 ', and the contrast and brightness can be further improved.

  Here, the light absorbing portions 53a, 53a,..., 53b, 53b,... Have a triangular cross section, but this may be a trapezoid. At this time, the trapezoidal short upper base is arranged on the viewer side and the trapezoidal long lower base is arranged on the light source side.

  FIG. 10 is a perspective view schematically showing the configuration of the optical function sheet layers 61 and 61 ′ of the video source unit in the video display devices 60 and 60 ′ according to the fifth modification. In FIG. 10, a cross-sectional view is shown on the right side of the perspective view for easy understanding. Since the configuration other than the optical function sheet layers 61 and 61 ′ is the same as the configuration of the video display device 39 and the video source unit 40 described above, the description thereof is omitted here. In the perspective view of FIG. 10, the front side of the paper is the observer side, and the back of the paper is the light source side.

  In the optical function sheet layer 61 shown in FIG. 10A, light absorbing portions 63a, 63a,..., 63b, 63b,... Having a triangular cross section are formed in a lattice shape, and each region surrounded by the lattice is a prism. It becomes part 62, 62, .... On the other hand, in the optical function sheet layer 61 ′ shown in FIG. 10B, the light absorbing portions 63a ′, 63a ′,..., 63b ′, 63b ′,. Each region formed and surrounded by a lattice is a prism portion 62 ′, 62 ′,.

  Also in the fifth modified example, the light absorbing portion is formed in a lattice shape in one optical function sheet layer. The lattice shape intersects with predetermined angles γ and δ. By forming in this way, desired optical characteristics can be obtained for a predetermined angle corresponding to γ and δ, and external light can be absorbed.

  Here, the light absorbing portions 63a, 63a,..., 63b, 63b,... Have a triangular cross section, but this may be a trapezoid. At this time, the trapezoidal short upper base is arranged on the viewer side and the trapezoidal long lower base is arranged on the light source side.

  Next, examples will be shown and described in more detail. However, the present invention is not limited to the scope of the examples.

  In the examples, the image display device corresponding to the first embodiment described above was operated as the image display device of the example, and the temperature reached by the optical function sheet layer at this time was examined, and the resulting image unevenness was evaluated. In the image display device of the example, an ultraviolet curable resin mainly composed of urethane acrylate having a Tg of 60 ° C. was used for the prism portion of the optical function sheet layer. On the other hand, an image display device of a comparative example was prepared using an ultraviolet curable resin mainly composed of urethane acrylate having a Tg of 55 ° C. in the prism portion. The evaluation of the unevenness generated in the video was judged by viewing the screen from the front. The visual observation was performed from a position separated from the center of the screen by a predetermined distance in the normal direction of the screen. Here, the predetermined distance is set to three times the length in the height direction of the screen.

  As a result, in each of the image display devices of the example and the comparative example, the temperature was highest at the portion where the electric circuit was arranged, and the temperature was 55 ° C.

  As a result of visual inspection of image unevenness, image unevenness was hardly recognized in the image display device of the example. On the other hand, in the video display device of the comparative example, unevenness occurred between the portion where the electric circuit was arranged and other portions.

  Although the present invention has been described in connection with the most practical and preferred embodiments at the present time, the present invention is not limited to the embodiments disclosed herein, The present invention can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and an image display device and an optical sheet accompanying such a change are also included in the technical scope of the present invention. Must be understood.

It is the figure which showed the cross section of the image source unit with which the display apparatus which concerns on 1st embodiment is equipped, and represented the layer structure and the optical path typically. It is the figure which expanded and showed a part of video source unit shown in FIG. It is the figure which showed typically the example of the temperature distribution produced in the front of a video display apparatus. It is the figure which showed the cross section of the video source unit with which the display apparatus which concerns on a 1st modification is equipped, and represented the layer structure typically. It is a figure for demonstrating the optical function sheet | seat layer among the display apparatuses which concern on a 2nd modification. It is a figure for demonstrating the optical function sheet | seat layer among the display apparatuses which concern on a 3rd modification. It is the figure which showed the cross section of the video source unit with which the display apparatus which concerns on 2nd embodiment is equipped, and represented the layer structure and the optical path typically. It is the figure which expanded and showed a part of video source unit shown in FIG. It is a figure for demonstrating the optical function sheet | seat layer among the display apparatuses which concern on a 4th modification. It is a figure for demonstrating the optical function sheet | seat layer among the display apparatuses which concern on a 5th modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image display apparatus 10 Image source unit 10a Image source 10b Optical sheet 11 Backlight 12 Polarizing plate 13 Liquid crystal panel 14 Polarizing plate 15 Adhesive layer 16 PET film layer 17 Optical functional sheet layer 18 Prism unit 19 Light absorption unit 20 Binder unit 21 Light Absorbing Particles 22 Adhesive Layer 23 TAC Film Layer 24 AG Layer 25 Optical Function Sheet Layer 39 Image Display Device 40 Image Source Unit 40a Image Source 40b Optical Sheet 41 Plasma Display Panel 42 Adhesive Layer 43 Optical Function Sheet Layer 44 Prism Unit 45 Light absorption part 46 PET film layer 47 AS layer 48 AG layer

Claims (16)

An image display device that emits an image from an image source to an observer,
An image source that emits an image that is self-luminous or combined with other light sources;
An image source unit comprising: an optical sheet disposed on the viewer side from the image source, and having a plurality of layers for controlling the light from the image source and emitting the light to the viewer side;
At least one of the plurality of layers is
A prism portion formed of a material having a predetermined glass transition point, which is arranged in parallel along the sheet surface so as to transmit light;
An optical functional sheet layer having a light absorbing portion arranged in parallel so as to be able to absorb light between the prism portions,
An image display device, wherein the glass transition point of the prism portion is higher than a temperature reached by the optical function sheet layer when an image is emitted from the image source unit.   The video display device according to claim 1, wherein the glass transition point of the prism portion is 56 ° C. or higher and 120 ° C. or lower.   The image display device according to claim 1, wherein the prism portion is an ultraviolet curable resin.   The light absorption part is filled with a binder made of a resin, and light absorption particles having an average particle diameter of 1 μm or more are dispersed in the binder. The video display device described in 1.   The prism portion and the light absorbing portion of the optical function sheet layer are formed to extend in the longitudinal direction while maintaining a predetermined cross section, and the two optical function sheet layers are laminated, and the two layers of optical The longitudinal direction of the light absorbing portion of one of the optical functional sheet layers of the functional sheet layer, and the longitudinal direction of the light absorbing portion of the other optical functional sheet layer of the two optical functional sheet layers The image display device according to claim 1, wherein the image display devices are stacked so as to have a predetermined angle.   The video display device according to claim 5, wherein the predetermined angle is 90 degrees.   5. The video display device according to claim 1, wherein the light absorbing portions of the optical function sheet layer are formed in a lattice shape that intersects at a predetermined angle. 6.   The video display device according to claim 7, wherein the predetermined angle is 90 degrees.   The video display device according to claim 1, wherein the video source unit further includes an antiglare film layer, a TAC film layer, and an adhesive layer in this order from the viewer side. An optical sheet used in the video display device according to any one of claims 1 to 9,
A plurality of layers arranged on the viewer side from the video source and controlling the light from the video source to be emitted to the viewer side;
At least one of the plurality of layers is
A prism portion formed of a material which is arranged in parallel along the sheet surface so as to transmit light and whose glass transition point is 56 ° C. or higher and 120 ° C. or lower;
An optical sheet comprising: an optical functional sheet layer having a light absorbing portion arranged in parallel so as to be able to absorb light between the prism portions. An optical sheet comprising a plurality of layers,
At least one of the plurality of layers is
A prism portion formed of an ultraviolet curable resin, which is arranged in parallel along the sheet surface so as to transmit light and has a glass transition point of 56 ° C. or higher and 120 ° C. or lower;
An optical sheet comprising: an optical functional sheet layer having a light absorbing portion arranged in parallel so as to be able to absorb light between the prism portions.   The optical sheet according to claim 11, wherein the light absorbing portion is filled with a binder made of a resin, and light absorbing particles having an average particle diameter of 1 μm or more are dispersed in the binder.   The prism portion and the light absorbing portion of the optical function sheet layer are formed to extend in the longitudinal direction while maintaining a predetermined cross section, and the two optical function sheet layers are laminated, and the two layers of optical The longitudinal direction of the light absorbing portion of one of the optical functional sheet layers of the functional sheet layer, and the longitudinal direction of the light absorbing portion of the other optical functional sheet layer of the two optical functional sheet layers The optical sheet according to claim 11, wherein the optical sheets are laminated so as to have a predetermined angle.   The optical sheet according to claim 13, wherein the predetermined angle is 90 degrees.   The optical sheet according to claim 11 or 12, wherein the light absorbing portions of the optical functional sheet layer are formed in a lattice shape that intersects at a predetermined angle.   The optical sheet according to claim 15, wherein the predetermined angle is 90 degrees.

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