JP2017111349A - Video source unit and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video source unit capable of improving utilization efficiency of a light from a light source.SOLUTION: A video source unit 10 comprises: a surface light source device 20 comprising a light source 25; and a liquid crystal panel 15 which is arranged on a light emission side of the surface light source device. The surface light source device comprises an optical sheet 26 for transmitting the light from the light source then emitting the light to the liquid crystal panel. The optical sheet 26 comprises: an optical function layer 30 which is bonded to a lower polarization plate of the liquid crystal panel and arranged in a thickness direction of the optical sheet 26; and an optical element layer 28. The optical function layer 30 comprises: plural light transmission parts 31 extending in one direction, having a prescribed cross section, and being arranged with a prescribed interval in a direction different from the extension direction; and interval parts 32 formed in the intervals of the plural light transmission parts. The optical element layer 28 is configured so that plural unit optical elements having a cross section which becomes salient to an opposite side of the optical function layer 30, and extending in one direction, are arranged in a direction different from the extension direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical sheet that emits light from a light source toward an observer, a surface light source device including the optical sheet, an image source unit, and a display device.

  A liquid crystal display device such as a liquid crystal television illuminates a liquid crystal panel having video information with a surface light source device from the back side. As a result, the illumination light is transmitted through the liquid crystal panel to obtain video information and emitted to the viewer side, so that the viewer can view the video. On the other hand, due to the nature of the liquid crystal panel, light incident at a large angle with respect to the normal of the panel surface cannot be used effectively, and is preferably excluded before incidence.

  On the other hand, Patent Document 1 discloses a light source, a brightness enhancement film (a sheet in which a plurality of prisms whose tops face the viewer side), a reflective polarizing film, and an LCF (light transmission part and light absorption part alternately). And a structure in which liquid crystal panels are arranged in this order. Thereby, the direction of the light emitted from the light source can be brought close to the normal direction of the panel surface of the liquid crystal panel, and the light use efficiency can be improved. In addition, light incident on the LCF at a large angle with respect to the panel surface of the liquid crystal panel is absorbed by the light absorbing portion provided here.

Special table 2011-501219 gazette

  When a sheet in which a plurality of prisms whose tops face the viewer side is used as described in Patent Document 1, light is refracted on an inclined surface and transmitted so that the direction of light is the panel surface of the liquid crystal panel Approach the normal direction. However, a part of the light is totally reflected on the inclined surface, and the exit angle is larger than the incident angle with respect to the normal direction of the panel surface (side lobe). Since the light by the side lobe is subsequently absorbed by the light absorbing portion, the light use efficiency decreases.

  In view of the above problems, an object of the present invention is to provide an image source unit that can improve the utilization efficiency of light from a light source. In addition, a display device using the video source unit is provided.

  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 embodiment.

  The invention according to claim 1 is an image source unit (10) comprising a surface light source device (20) having a light source (25) and a liquid crystal panel (15) disposed on the light output side of the surface light source device. The surface light source device includes an optical sheet (30) that transmits light from the light source and emits light to the liquid crystal panel, and the optical sheet is bonded to the lower polarizing plate of the liquid crystal panel, and the thickness of the optical sheet. An optical functional layer (30) arranged in the vertical direction and an optical element layer (28). The optical functional layer has a predetermined cross section and extends in one direction, and is different from the extending direction. A plurality of light transmission portions (31) arranged at a predetermined interval, and a space portion (32) formed at the interval of the plurality of light transmission portions, and the optical element layer is opposite to the optical functional layer A unit optical element having a convex cross section and extending in one direction with the cross section 29) are arrayed in a direction different from that of the extending direction, which is a video source unit.

  According to a second aspect of the present invention, in the image source unit (10) according to the first aspect, the one direction in which the light transmitting portion (31) extends and the one direction in which the unit optical element (29) extends are defined by the optical sheet. The angle formed in a front view is 10 ° or less.

  The invention according to claim 3 is the image source unit (10) according to claim 1 or 2, further comprising a base layer (27), and an optical functional layer (30) on one surface of the base layer. The optical element layer (28) is laminated on the other surface of the base material layer.

  According to a fourth aspect of the present invention, in the image source unit (10) according to any one of the first to third aspects, the optical function layer (30) has a light-transmitting portion (31) of the optical function layer having a trapezoidal cross section. The lower bottom of the trapezoidal cross section faces the optical element layer (28) side.

  According to a fifth aspect of the present invention, in the image source unit according to any one of the first to third aspects, the optical functional layer has a light-transmitting portion of the optical functional layer having a trapezoidal cross section, and the trapezoidal cross section. Among them, the short upper base faces the optical element layer (28) side.

  A sixth aspect of the present invention is the image source unit according to any one of the first to fifth aspects, further comprising a reflective polarizing film (235).

  According to a seventh aspect of the present invention, in the video source unit according to the sixth aspect, the reflective polarizing film (235) is disposed between the optical functional layer (30) and the optical element layer (28). .

  The invention according to claim 8 is the image source unit according to any one of claims 1 to 7, further comprising a light diffusion layer (536).

  According to a ninth aspect of the present invention, in the video source unit according to the eighth aspect, the light diffusion layer is a light diffusion layer that performs anisotropic light diffusion.

  According to a tenth aspect of the present invention, in the video source unit according to the eighth aspect, the light diffusion layer has a prism or lenticular lens shape.

  According to an eleventh aspect of the present invention, in the image source unit (10) according to the tenth aspect, the direction in which the prism or lenticular lens extends is in front of the optical sheet with respect to one direction in which the transmission part of the optical functional layer extends. It is an angle that makes 90 ° in view.

  According to a twelfth aspect of the present invention, in the video source unit according to any one of the eighth to eleventh aspects, the light diffusion layer is disposed on the opposite side of the optical functional layer with the optical element layer interposed therebetween.

  According to a thirteenth aspect of the present invention, in the video source unit according to any of the eighth to eleventh aspects, the light diffusion layer is disposed on the opposite side of the optical element layer with the optical functional layer interposed therebetween.

  According to a fourteenth aspect of the present invention, in the image source unit according to any one of the eighth to eleventh aspects, the light diffusion layer is disposed between the optical functional layer and the optical element layer.

  According to a fifteenth aspect of the present invention, in the video source unit according to any one of the first to fourteenth aspects, the refractive index of the intermediate portion is formed smaller than the refractive index of the light transmitting portion.

  According to a sixteenth aspect of the present invention, in the video source unit according to any one of the first to fourteenth aspects, a layer that reflects light is formed at an interface between the light source and the light transmission unit.

  According to a seventeenth aspect of the present invention, in the video source unit according to any one of the first to fourteenth aspects, a material that absorbs light is contained in the intermediate portion.

  According to an eighteenth aspect of the present invention, in the video source unit according to any one of the first to seventeenth aspects, the light source is disposed on a side where the unit optical element of the optical element layer of the optical sheet is convex.

  A nineteenth aspect of the present invention is a display device comprising: the video source unit according to any one of the first to eighteenth aspects; and a housing that houses the video source unit.

  ADVANTAGE OF THE INVENTION According to this invention, while emitting an appropriate light efficiently, the light which produces a defect can be absorbed effectively, the utilization efficiency of light can be improved, for example, the brightness | luminance of the emitted light can be raised.

It is a disassembled perspective view explaining the image source unit 10 concerning a 1st form. 3 is an exploded view showing a cross section of the surface light source device 20. FIG. FIG. 3 is an enlarged view paying attention to a base material layer 27 and an optical element layer 28 in FIG. 2. FIG. 3 is an enlarged view focusing on a base material layer 27 and an optical function layer 30 in FIG. 2. It is a figure explaining a 2nd form. It is a figure explaining the example of the optical path in a 2nd form. It is a figure explaining the surface light source device 220. FIG. It is a figure explaining the optical function layer. It is a figure explaining the optical function layer 430. FIG. FIG. 5 is an exploded perspective view illustrating a video source unit 510. It is a figure explaining the light-diffusion layer 536. FIG. FIG. 12A is a diagram illustrating the light diffusion layer 536 ′, and FIG. 12B is a diagram illustrating the light diffusion layer 536 ″.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings. However, the present invention is not limited to these forms. In the drawings shown below, the shape may be exaggerated and deformed for easy viewing.

  FIG. 1 is a diagram illustrating a first embodiment, and is an exploded perspective view showing a video source unit 10 included in a display device. In addition to the image source unit 10, the description of the display device is omitted, but the display device operates as a display device, such as a housing for housing the image source unit, a power source for operating the image source unit, and an electronic circuit for controlling the image source unit. It is equipped with the usual equipment required for. Hereinafter, the video source unit 10 will be described.

  The video source unit 10 includes a liquid crystal panel 15, a surface light source device 20, and a functional film 40. In FIG. 1, the viewer is on the paper.

  The liquid crystal panel 15 includes an upper polarizing plate 13 disposed on the functional film 40 side (observer side), a lower polarizing plate 14 disposed on the surface light source device 20 side, an upper polarizing plate 13 and a lower polarizing plate 14. And a liquid crystal cell layer 12 disposed between the two. The upper polarizing plate 13 and the lower polarizing plate 14 decompose the incident light into two orthogonal polarization components (P wave and S wave), and a polarization component in one direction (direction parallel to the transmission axis) (for example, P And has a function of absorbing a polarization component (for example, S wave) in the other direction (direction parallel to the absorption axis) orthogonal to the one direction.

  An electric field can be applied to the liquid crystal cell layer 12 for each region where one pixel is formed. Then, the orientation of the pixel to which the electric field is applied changes. A polarization component (for example, P wave) in a specific direction that has passed through the lower polarizing plate 14 disposed on the surface light source device 20 side (that is, the light incident side) has a polarization direction of 90 ° when passing through a pixel to which an electric field is applied. While rotating, it maintains its polarization direction as it passes through a pixel to which no electric field is applied. Therefore, depending on whether or not an electric field is applied to the pixel, the polarization component (for example, P wave) in a specific direction transmitted through the lower polarizing plate 14 further passes through the upper polarizing plate 13 disposed on the light output side of the lower polarizing plate 14. Alternatively, it is possible to control whether the light is absorbed and blocked by the upper polarizing plate 13.

  In this way, the liquid crystal panel 15 is configured to be able to express an image by controlling transmission or blocking of light from the surface light source device 20 for each pixel.

The liquid crystal panel is configured to be able to provide an image to the observer based on such a principle. Due to the nature of the liquid crystal panel, the contrast and efficiency (transmittance) of the emitted light are excellent with respect to incident light from the normal direction of the liquid crystal panel. However, with respect to the incident light obliquely with respect to the normal direction of the liquid crystal panel and the observation by the observer from the oblique direction, there are problems of a decrease in contrast and a low efficiency (transmittance). That is, it is effective to increase the incident light from the normal direction of the liquid crystal panel in order to increase the light use efficiency.
The kind of liquid crystal panel is not particularly limited, and examples thereof include known types of liquid crystal panels. These include, for example, TN, STN, VA, MVA, IPS, OCB, and the like.

Next, the surface light source device 20 will be described. FIG. 2 shows a part of an exploded cross-sectional view when the surface light source device 20 is cut along the line indicated by II-II in FIG.
The surface light source device 20 is an illuminating device that is disposed on the opposite side of the liquid crystal panel 15 from the observer side and emits planar light to the liquid crystal panel 15. As can be seen from FIGS. 1 and 2, the surface light source device 20 of this embodiment is configured as an edge light type surface light source device, and includes a light guide plate 21, a light source 25, an optical sheet 26, and a reflection sheet 39. .

  As can be seen from FIGS. 1 and 2, the light guide plate 21 has a base portion 22 and a back optical element 23. The light guide plate 21 is a plate-like member as a whole formed of a light-transmitting material. In this embodiment, one plate surface side that is an observer side of the light guide plate 21 is a smooth surface, and the other plate surface side opposite to this is a back surface, and a back optical element 23 is formed.

  Various materials can be used as the material forming the base 22 and the back optical element 23. However, a material that is widely used as a material for an optical sheet incorporated in a display device and has excellent mechanical characteristics, optical characteristics, stability, workability, and the like, and can be obtained at low cost can be used. This includes, for example, a polymer resin having an alicyclic structure, a methacrylic resin, a polycarbonate, a polystyrene, an acrylonitrile-styrene copolymer, a methyl methacrylate-styrene copolymer, an ABS resin, a polyethersulfone, and the like, Examples thereof include epoxy acrylate and urethane acrylate-based reactive resins (ionizing radiation curable resins and the like).

  The base portion 22 is a portion serving as a base of the back optical element 23 and is a plate-like portion having a predetermined thickness.

The back surface optical element 23 has a concavo-convex shape formed on the back surface side of the base portion 22 (the side opposite to the side on which the optical sheet 26 is disposed), and a plurality of triangular prism-shaped back surface optical elements 23 are arranged. The back surface optical element 23 has a columnar shape in which the ridge line of the convex portion extends in the left-right direction in FIG. 1, and the plurality of back surface optical elements 23 are arranged side by side at a predetermined pitch in a direction orthogonal to the extending direction. The back optical element 23 of this embodiment has a triangular cross section, but is not limited to this, and may be any shape such as a polygon, a hemisphere, a part of a sphere, or a lens shape.
The arrangement direction of the plurality of back surface optical elements 23 is preferably the light guide direction. In other words, the ridgelines of the respective back surface optical elements 23 are arranged in a direction away from the light source and in the direction in which the light source 25 is arranged, or in the direction in which the light source extends in the case of one long light source.

  The “triangular shape” in the present specification includes not only a triangular shape in a strict sense but also a substantially triangular shape including limitations in manufacturing technology, errors in molding, and the like. Similarly, terms used in the present specification to specify other shapes and geometric conditions, for example, terms such as “parallel”, “orthogonal”, “ellipse”, “circle”, etc. are bound to the strict meaning. Therefore, it should be interpreted including an error to the extent that a similar optical function can be expected.

  The light guide plate 21 having such a configuration can be manufactured by extrusion molding or by molding the back optical element 23 on a base material. In the light guide plate 21 manufactured by extrusion molding, the base portion 22 and the back surface optical element 23 can be integrally formed. Moreover, when manufacturing the light-guide plate 21 by shaping | molding, the back surface optical element 23 may be the same resin material as the base 22, or a different material.

Returning to FIGS. 1 and 2, the light source 25 will be described. In the present embodiment, the light source 25 is a light source that is disposed on one side of a set of side surfaces in the direction in which the back optical elements 23 are arranged, of the two opposing side surfaces of the base 22 of the light guide plate 21. However, light sources may be arranged on both sides of the set of side surfaces. At this time, the shape of the back surface optical element 23 is also changed in accordance with a known example.
The type of the light source is not particularly limited, but may be configured in various forms such as a fluorescent lamp such as a linear cold cathode tube, a point LED (light emitting diode), or an incandescent lamp. In this embodiment, the light source 25 is composed of a plurality of LEDs. The output of each LED, that is, the lighting and extinguishing of each LED, and / or the brightness when each LED is lit, is controlled by another control unit (not shown). It can be adjusted independently from the output of the.

  Next, the optical sheet 26 will be described. As can be seen from FIG. 1 and FIG. 2, the optical sheet 26 is provided on the surface of the base material layer 27 formed in a sheet shape and the surface of the base material layer 27 facing the light guide plate 21, that is, on the light incident side surface. The prism layer 28 functioning as the optical element layer, and the optical functional layer 30 provided on the surface of the base material layer 27 opposite to the prism layer 28, that is, on the light output side surface.

  As will be described later, the optical sheet 26 changes the traveling direction of the light incident from the light incident side and emits the light from the light output side, thereby intensively improving the luminance in the front direction (normal direction) (condensing light). Function). Furthermore, it has a function (light absorption function) of absorbing light traveling at a large angle with respect to the front direction.

As shown in FIGS. 1 and 2, the base material layer 27 is a flat sheet-like member that supports the prism layer 28 and the optical function layer 30 in this embodiment.
Various materials can be used as the material forming the base material layer 27. However, a material that is widely used as a material for an optical sheet incorporated in a display device and has excellent mechanical characteristics, optical characteristics, stability, workability, and the like, and can be obtained at low cost can be used. Examples thereof include polyethylene terephthalate (PET), triacetyl cellulose (TAC), methacrylic resin, polycarbonate and the like. Among these, considering the combination of the surface light source device 20 and the lower polarizing plate 14, it is preferable to use TAC, methacrylic resin, and polycarbonate having a low birefringence. Furthermore, it is more desirable to use a polycarbonate having a high glass transition point in applications that require high heat resistance such as in-vehicle use. Specifically, the glass transition point of polycarbonate is 143 ° C., which is generally suitable for in-vehicle applications that require durability at 105 ° C.

The prism layer 28 functions as an optical element layer, and unit prisms 29 as a plurality of unit optical elements are arranged along the light incident surface side of the base material layer 27. More specifically, the unit prisms 29 are formed so as to extend in a direction orthogonal to the arrangement direction while maintaining a predetermined cross-sectional shape that is convex on the side opposite to the optical functional layer 30 shown in FIG. It is the made columnar member. The extending direction is the same as the extending direction of the rear optical element 23 and the light transmitting portion 31 of the optical functional layer 30 described later, and is a direction orthogonal to the light guide direction of the light guide plate 21 in a front view of the optical sheet 26. . Therefore, the plurality of unit prisms 29 are arranged in the light guide direction.
In this embodiment, since the unit optical element has a triangular cross section and satisfies the prism shape, the unit optical element is referred to as a unit prism, and the optical element layer is referred to as a prism layer. However, the unit optical element does not necessarily have a prism shape, and may have a shape having a curved surface in part or in whole.

  The longitudinal direction, which is the direction in which the unit prism 29 extends, intersects the transmission axis of the lower polarizing plate 14 of the liquid crystal panel 15 when the display device is observed from the front (in front view). Preferably, the longitudinal direction of the unit prism 29 of the optical sheet 26 intersects the transmission axis of the lower polarizing plate 14 of the liquid crystal panel 15 at an angle greater than 45 ° and smaller than 135 ° in the front view. The angle here means the smaller one of the angles formed by the longitudinal direction of the unit prism 29 and the transmission axis of the lower polarizing plate 14, that is, an angle of 180 ° or less. . In particular, in this embodiment, the longitudinal direction of the unit prism 29 of the optical sheet 26 is orthogonal to the transmission axis of the lower polarizing plate 14 of the liquid crystal panel 15, and the direction in which the unit prisms 29 of the optical sheet 26 are arranged is the liquid crystal The panel 15 is preferably parallel to the transmission axis of the lower polarizing plate 14.

Next, the cross-sectional shape of the unit prism 29 will be described. FIG. 3 is an enlarged view of a part of the base material layer 27 and the prism layer 28 in FIG. Where n _d denotes the normal direction of the layer plane of the base layer 27.

As can be seen from FIG. 3, in this embodiment, the unit prism 29 has an isosceles triangle cross section in which the side surface of the light guide plate 21 of the base material layer 27 protrudes. That is, the width of the unit prism 29 in the direction parallel to the layer surface of the base material layer 27 decreases as the distance from the base material layer 27 increases along the normal direction _nd of the base material layer 27. As described above, the unit prism (unit optical element) 29 is formed to be convex on the side opposite to the optical functional layer 30. Therefore, the image source unit 10 is an element that protrudes toward the light source 25.

Further, in this embodiment, the outer contour of the unit prisms 29 as axis of symmetry an axis parallel to the normal direction n _d of the base layer 27, has a line-symmetric cross-section is an isosceles triangle.

Here, the dimensions of the unit prism 29 are not particularly limited, but the apex angle θ _p is preferably 50 ° or more and 80 ° or less, and the base width W _p and the pitch P _p are preferably 10 μm or more and 100 μm or less.

In this embodiment, the unit optical element having a triangular cross-sectional shape as described above has been described as a unit prism, but the unit optical element is not limited to this, and a trapezoid in which the apex of the triangle is a short upper base or The polygonal shape in which the shape of the slope is a polygonal line may be used. Alternatively, the slope portion may be a convex curve or a concave curve instead of the prism shape.
In addition, the plurality of unit optical elements may have the same cross-sectional shape, or may be the same, or may be arranged so as to have different cross-sectional shapes at intervals of one pitch or with other regularity.

  The material constituting the unit optical element (unit prism in this embodiment) can be the same as that of the base material layer. Here, as will be described later, it is preferable that the refractive index is 1.55 or more from the viewpoint of appropriately totally reflecting light on the slope and directing it toward the viewer. However, since a material with a refractive index that is too high is likely to break, the refractive index is preferably 1.61 or less. More preferably, it is 1.58 or less.

  Next, returning to FIGS. 1 and 2, the optical functional layer 30 will be described. The optical functional layer 30 of the present embodiment efficiently transmits the light whose direction has been changed by the prism layer (optical element layer) 28 while traveling in a direction close to the normal direction of the panel surface of the liquid crystal panel 15. Absorbs light traveling at a large angle with respect to the normal direction. Thereby, high quality image light can be provided to the observer. FIG. 4 is an enlarged view of a part of FIG. 2 focusing on the base material layer 27 and the optical functional layer 30.

  The optical functional layer 30 has a cross section shown in FIG. 4 and a shape extending to the back / near side of the drawing. That is, in the cross section shown in FIG. 4, the light transmitting portion 31 that is substantially trapezoidal, and the light absorbing portion 32 that functions as an intermediate portion in which the cross section formed between two adjacent light transmitting portions 31 is substantially trapezoidal. I have. As can be seen from FIGS. 1, 2, and 4, the direction in which the light transmitting portion 31 and the light absorbing portion 32 extend is the same as the direction in which the unit prism 29 of the prism layer 28 extends. The direction in which the light absorbing portions 32 are alternately arranged is the same as the direction in which the plurality of unit prisms 29 are arranged.

  The light transmission part 31 is a part whose main function is to transmit light. In this embodiment, in the cross section shown in FIGS. 2 and 4, a long bottom on the base material layer 27 side, the opposite side (observer side) ) Having a substantially trapezoidal cross-sectional shape having a short upper base. The light transmitting portions 31 extend along the layer surface of the base material layer 27 while maintaining the cross section, and are arranged at a predetermined interval in a direction different from the extending direction. An interval having a substantially trapezoidal cross section is formed between the adjacent light transmission portions 31. Therefore, the interval has a long lower base on the upper base side (opposite side to the optical element layer 28 side) of the light transmission part 31, and a short upper side on the lower base side (optical element layer 28 side) of the light transmission part 31. It has a trapezoidal cross section with a bottom, and is filled with necessary materials to be described later, thereby forming an intermediate portion (light absorbing portion 32 in this embodiment). In this embodiment, the adjacent light transmission parts 31 are connected on the long bottom side.

The light transmission portion 31 has a refractive index is a N _t. Such a light transmission part 31 can be formed by hardening a transmission part constituent composition. Details will be described later. In While not the value of the refractive index N _t is particularly limited, the refractive index from the viewpoint of totally reflecting the appropriate light at the interface between the light absorbing portion 32 in the slope of a trapezoidal cross-section, as will be described later 1.55 Preferably there is. However, since a material with a refractive index that is too high is likely to break, the refractive index is preferably 1.61 or less. More preferably, it is 1.56 or less.

The light absorbing portion 32 is a portion formed between the adjacent light transmitting portions 31 and arranged at the interval described above, and has a cross-sectional shape similar to the cross-sectional shape of the interval. Therefore, the short upper base faces the optical element layer 28 side, and the long lower base is the side opposite to the optical element layer 28 side. And the light absorption part 32 is comprised so that a refractive index may be _Nr and can absorb light. Specifically, light absorbing particles are dispersed in a binder having a refractive index of _Nr . Refractive index N _r is a refractive index lower than the refractive index N _t of the light transmitting portion 31. Thus, by making the refractive index of the light absorbing portion 32 smaller than the refractive index of the light transmitting portion 31, the light incident on the light transmitting portion 31 under a predetermined condition is appropriately totally reflected at the interface with the light absorbing portion 32. Can be made. The value of the refractive index _Nr is not particularly limited, but is preferably 1.50 or less from the viewpoint of appropriately performing the total reflection, and more preferably 1.47 or more from the viewpoint of availability. More preferably, it is 1.49 or more.

The difference in refractive index between the refractive index _Nt of the light transmitting portion 31 and the refractive index _Nr of the light absorbing portion 32 is not particularly limited, but is preferably 0.05 or more and 0.14 or less. By increasing the refractive index difference, more light can be totally reflected.

The optical function layer 30 is not particularly limited. For example, the light transmission part 31 and the light absorption part 32 are formed as follows. That is, it is preferable that the pitch of the light transmission part 31 and the light absorption part 32 represented by _Pk in FIG. 4 is 20 μm or more and 100 μm or less. Further, the angle formed by the interface on the hypotenuse between the light absorbing portion 32 and the light transmitting portion 31 indicated by θ _k in FIG. 4 and the normal of the layer surface of the optical functional layer 30 is 1 ° or more and 10 ° or less. Is preferred. And it is preferable that the thickness of the light transmission part 32 shown by _Dk in FIG. 4 is 50 micrometers or more and 150 micrometers or less. By setting it within these ranges, the balance between light transmission and light absorption can be made appropriate.

  In this embodiment, an example in which the interface between the light transmitting portion 31 and the light absorbing portion 32 is straight in the cross section is shown, but not limited to this, a polygonal line shape, a curved surface shape that is convex, a curved surface shape that is concave, etc. Also good. Moreover, the cross-sectional shape may be the same in the some light transmissive part 31 and the light absorption part 32, and a different cross-sectional shape may have predetermined regularity.

  As described above, the optical sheet 26 has the optical element layer 28 and the optical functional layer 30, and the unit optical elements 29 are arranged so that the optical element layer 28 is convex on the side opposite to the optical functional layer 30. Is done. Here, it is preferable that the direction in which the unit optical element 29 extends and the direction in which the light transmission part 31 and the light absorption part 32 of the optical functional layer 30 extend form an angle of 10 ° or less in the front view of the optical sheet 26. . This enables efficient light control as will be described later.

The optical sheet 26 can be manufactured as follows, for example.
First, the light transmission part 31 is formed on one surface side of the base material layer 27. This inserts the base material sheet used as the base material layer 27 between the die roll which has the shape which can transfer the shape of the light transmission part 31 on the surface, and the nip roll arrange | positioned so as to oppose this. At this time, the mold roll and the nip roll are rotated while supplying the composition constituting the light transmitting portion between the base sheet and the mold roll. As a result, a groove corresponding to the light transmitting portion formed on the surface of the mold roll (a shape obtained by reversing the shape of the light transmitting portion) is filled with the composition that constitutes the light transmitting portion, and the composition becomes the surface of the mold roll. It will be along the shape.

  Here, examples of the composition constituting the light transmission part include ionizing radiation curable resins such as epoxy acrylate, urethane acrylate, polyether acrylate, polyester acrylate, and polythiol.

  Light for curing with a light irradiation device is irradiated from the substrate sheet side to the composition constituting the light transmission portion sandwiched between the mold roll and the substrate sheet and filled therein. Thereby, a composition can be hardened and the shape can be fixed. And the base material layer 27 and the shape | molded light transmission part 31 are released from a metal mold | die roll with a mold release roll.

  Next, the light absorption part 32 is formed. In order to form the light absorbing portion 32, first, the composition constituting the light absorbing portion is filled in the interval between the formed light transmitting portions 31. Thereafter, the surplus composition is scraped off with a doctor blade or the like. Then, the remaining composition can be cured by a light irradiation device from the light transmitting portion 31 side to form an intermediate portion (light absorbing portion 32).

  The material used as the light absorbing portion is not particularly limited, but for example, it is colored in a photocurable resin such as urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, and butadiene (meth) acrylate. And a composition in which the light absorbing particles are dispersed.

Further, instead of dispersing the light absorbing particles, the entire light absorbing portion can be colored with a pigment or a dye.
When using light-absorbing particles, light-absorbing colored particles such as carbon black are preferably used. However, the present invention is not limited to these, and selectively absorbs a specific wavelength according to the characteristics of image light. Colored particles may be used. Specific examples include organic fine particles colored with metal salts such as carbon black, graphite, and black iron oxide, dyes, pigments, colored glass beads, and the like. In particular, colored organic fine particles are preferably used from the viewpoints of cost, quality, availability, and the like. The average particle diameter of the colored particles is preferably 1.0 μm or more and 20 μm or less.

  Thereby, a laminated body in which the optical functional layer 30 is laminated on one surface of the base material layer 27 is formed. A unit prism 29 is formed on the other surface of the base material layer 27 opposite to the side on which the optical functional layer 30 is laminated. Thereby, the optical sheet 26 is obtained. Various materials can be used as the material forming the unit prism 29. However, it is widely used as a material for an optical sheet incorporated in a display device, and has excellent mechanical properties, optical properties, stability, workability, and the like, and can be obtained at low cost, such as acrylic, styrene, polycarbonate, Transparent resins mainly composed of one or more of polyethylene terephthalate, acrylonitrile and the like, and epoxy acrylate and urethane acrylate-based reactive resins (ionizing radiation curable resins and the like) can be suitably used.

In this embodiment, the example in which the optical element layer (prism layer) 28 and the optical function layer 30 are arranged on the front and back of one base material layer 27 is described. However, the present invention is not limited to this, and the prism layer 28 and the optical function layer 30 are individually provided. It has a base material layer, and it is good also as an optical sheet by bonding together base material layers. Further, when the prism layer 28 and the optical function layer 30 are individually provided with base layers, the base layers are arranged with a predetermined interval without being bonded to each other, or simply by being brought into contact with each other without being bonded. May be. In that case, a mat surface (a minute uneven surface) may be formed on the surface facing the predetermined interval or the surface to be contacted. Examples of the mat surface include an example in which the surface roughness is in the range of 0.1 μm to 0.5 μm in terms of Ra (μm) (JIS B 0601 (2001) arithmetic average roughness). Thereby, optical contact and scintillation can be prevented.
However, by arranging the optical element layer (prism layer) 28 and the optical functional layer 30 on the front and back of one base material layer 27 as in the present embodiment, the interface can be reduced, and the interface reflection can be reduced to efficiently transmit light. It is possible to provide.

  In the present invention, the optical functional layer 30 and the above-described lower polarizing plate 14 of the optical sheet are bonded with a pressure-sensitive adhesive so as not to have an air interface. Accordingly, the number of interfaces can be further reduced, interface reflection can be reduced, light can be efficiently provided, and luminance can be increased.

  Returning to FIG. 1 and FIG. 2, the reflection sheet 39 of the surface light source device 20 will be described. The reflection sheet 39 is a member that reflects the light emitted from the back surface of the light guide plate 21 and makes the light enter the light guide plate 21 again. The reflection sheet 39 is a sheet that is capable of so-called specular reflection, such as a sheet made of a material having a high reflectance such as a metal, a sheet including a thin film (for example, a metal thin film) made of a material having a high reflectance as a surface layer, It can be preferably applied.

  The functional film 40 is a layer that is disposed on the light output side of the liquid crystal panel 15 and has functions of improving the quality of the video light and protecting the video source unit 10. Examples thereof include an antireflection film, an antiglare film, a hard coat film, a color tone correction film, a light diffusion film, and the like, and these are constituted by combining them alone or in combination.

  Next, the operation of the display device having the above configuration will be described with an example of the optical path. However, the optical path example is conceptual for explanation, and does not strictly represent the degree of reflection or refraction.

  First, as shown in FIG. 2, the light emitted from the light source 25 enters the light guide plate 21 through the light incident surface on the side surface of the light guide plate 21. FIG. 2 shows an example of an optical path of the light L21 and L22 incident on the light guide plate 21 from the light source 25 as an example.

  As shown in FIG. 2, the light L21 and L22 incident on the light guide plate 21 repeats total reflection due to a difference in refractive index with air on the light exit side surface of the light guide plate 21 and the back surface on the opposite side, thereby guiding the light guide direction (FIG. Proceed to the right of page 2).

  However, the back optical element 23 is disposed on the back surface of the light guide plate 21. For this reason, as shown in FIG. 2, the light L21, L22 traveling in the light guide plate 21 has its traveling direction changed by the back surface optical element 23, and is incident on the light exit surface and the back surface at an incident angle less than the total reflection critical angle. There is also. In this case, the light can be emitted from the light exit surface of the light guide plate 21 and the back surface on the opposite side.

  Lights L21 and L22 emitted from the light exit surface travel to the optical sheet 26 disposed on the light exit side of the light guide plate 21. On the other hand, the light emitted from the back surface is reflected by the reflection sheet 39 disposed on the back surface of the light guide plate 21, enters the light guide plate 21 again, and travels through the light guide plate 21.

  The light traveling in the light guide plate 21 and the light whose direction is changed by the back surface optical element 23 and reaching the light exit surface at an incident angle less than the total reflection critical angle are in each area along the light guide direction in the light guide plate 21. Arise. For this reason, the light traveling in the light guide plate 21 is gradually emitted from the light exit surface. Thereby, the light quantity distribution along the light guide direction of the light emitted from the light exit surface of the light guide plate 21 can be made uniform.

The light emitted from the light guide plate 21 then enters the optical sheet 26. The unit prism 29 of the optical sheet 26 is totally reflected on the surface opposite to the surface on which the light is incident on the unit prism 29 and changed its direction to collect light (the direction of light in a direction approaching the normal direction of the liquid crystal panel). Effect to change). That is, as indicated by L31 in FIG. 3, the light incident on the unit prism 29 is totally reflected at the interface based on the refractive index difference between the unit prism 29 and air. At that time, the oblique side of the unit prism 29 is inclined by θ _p / 2 with respect to the sheet surface normal line n _d (same as the normal line of the liquid crystal panel), so that the reflected light at the interface is the normal line n _d rather than the incident light. The angle will be close to.

That is, in the prism layer 28, the light traveling direction is narrowed down to a narrow angle range centering on the front direction on the surface parallel to the arrangement direction of the unit prisms 29 of the optical sheet 26. Therefore, the brightness in the front direction can be increased by the optical action of the optical sheet 26.
As described above, the prism layer having the unit prism 29 convex toward the light incident side can efficiently collect light without generating side lobes.

The light condensed by the prism layer 28 enters the optical function layer 30. Since the light incident on the optical functional layer 30 is basically collected by the prism layer 28, the light transmitting portion 31 is not reached at the interface with the light absorbing portion 32, for example, as indicated by L 41 in FIG. Even if it passes through or reaches the interface with the light absorbing portion 32 as indicated by L 42 in FIG. 4, it can be totally reflected and passes through the light transmitting portion 31.
On the other hand, as indicated by L43 in FIG. 4, the light incident on the optical functional layer 30 at a large angle with respect to the normal to the sheet surface for some reason is absorbed by the light absorbing portion 32 and is not provided to the liquid crystal panel 15.

  With such an optical sheet 26, the light from the light guide plate 21 is efficiently collected, and the light that has not been collected is absorbed by the light absorption unit, so that appropriate light can be efficiently provided to the liquid crystal panel. It is possible to greatly improve the light utilization efficiency.

Further, the optical path will be described. The light emitted from the surface light source device 20 as described above enters the lower polarizing plate 14 of the liquid crystal panel 15. The lower polarizing plate 14 transmits one polarization component of incident light and absorbs the other polarization component. The light transmitted through the lower polarizing plate 14 selectively passes through the upper polarizing plate 13 according to the state of electric field application to each pixel. In this way, the liquid crystal panel 15 selectively transmits the light from the surface light source device 20 for each pixel, so that an observer can observe an image. At that time, the image light is provided to the observer through the functional film 40, and the quality of the image is improved.
In the present invention, since the lower polarizing plate 14 and the optical sheet 26 are directly laminated with an adhesive, there is no interface with air, interface reflection is reduced, and light can be efficiently provided to the front side. As a result, the luminance can be increased.

  FIG. 5 is a view for explaining the second embodiment and corresponds to FIG. In this embodiment, an optical sheet 126 is applied in place of the optical sheet 26 in the surface light source device 120, and other configurations are the same as those of the video source unit 10.

The optical sheet 126 includes a base material layer 27 and a prism layer 28 as in the optical sheet 26, but the optical functional layer 130 is opposite to the optical functional layer 30 in the direction of the layer. A base material layer 127 for the optical function layer 130 is disposed on the viewer side of the optical function layer 130. The base material layer 127 can be configured similarly to the base material layer 27. In this embodiment, the optical sheet 126 is directly laminated on the lower polarizing plate 14 with an adhesive.
Even if such an optical sheet 126 is used, the light utilization efficiency can be greatly improved. FIG. 6 shows an example of an optical path in the optical function layer 130. FIG. 6 corresponds to FIG. In addition, the progress of light until it enters the optical functional layer 130 is the same as that of the surface light source device 20 described above.

The light condensed by the prism layer 28 enters the optical function layer 130. Since the light incident on the optical functional layer 130 is basically collected by the prism layer 28, the light transmitting portion 31 is not reached at the interface with the light absorbing portion 32, for example, as indicated by L 61 in FIG. Even if the light is transmitted or reaches the interface with the light absorbing portion 32 as indicated by L 62 in FIG. 6, it can be totally reflected and transmitted through the light transmitting portion 31. At this time, in this embodiment, the light is condensed in the front direction as can be seen from L62 by the inclination direction of the interface between the light transmission part 31 and the light absorption part 32.
On the other hand, as indicated by L63 in FIG. 6, the light incident on the optical functional layer 130 at a large angle with respect to the normal to the sheet surface for some reason is absorbed by the light absorbing portion 32 and is not provided to the liquid crystal panel 15.

  FIG. 7 is a diagram for explaining the third embodiment and corresponds to FIG. In this embodiment, an optical sheet 226 is applied instead of the optical sheet 26, and the other configurations are the same as those of the video source unit 10.

  In the optical sheet 226, the reflective polarizing film 235 and the optical functional layer base material layer 227 are arranged in this order from the base material layer 27 side between the base material layer 27 and the optical functional layer 130 described above. It is an example. Since other than this is the same as the optical sheet 26 described above, the reflective polarizing film 235 and the optical functional layer base material layer 227 will be described here.

  As the reflective polarizing film 235, a known film can be applied. That is, only light having a predetermined polarization direction is transmitted and light having another polarization direction is reflected. Thereby, the reflected light can be reused as is well known, and the light utilization efficiency can be increased.

  The base layer 227 for the optical functional layer is a layer that becomes the base of the optical functional layer 30 and can be configured in the same manner as the base layer 27.

  In this embodiment, the example in which the reflective polarizing film 235 is disposed between the base material layer 27 and the optical functional layer 30 has been described. However, the position is not limited to this, and the reflective polarizing film 235 is optical. You may arrange | position on the observer side surface of the functional layer 30. FIG. At this time, similarly to the optical sheet 26, the prism layer 28 and the optical functional layer 30 can be arranged on the front and back of the base material layer 27.

  Moreover, although the example in which the optical function layer 30 is applied has been described in this embodiment, the optical function layer 130 and the base material layer 127 may be applied instead.

  The optical sheet of the present embodiment is also directly laminated with an adhesive on the lower polarizing plate, and exhibits the above effects.

  In the above embodiment, the edge type surface light source device in which the light source is arranged on the side surface has been described. However, a direct type surface light source device of a type in which the light source is arranged on the back surface may be used.

  FIG. 8 is a diagram for explaining the fourth embodiment and corresponds to FIG. In this embodiment, an optical sheet 326 is applied instead of the optical sheet 26, and the other configurations are the same as those of the video source unit 10.

  The optical sheet 326 includes a base material layer 27 and a prism layer 28 (not shown in FIG. 8) as in the optical sheet 26, but includes an optical functional layer 330 instead of the optical functional layer 30. This is different from the optical sheet 26 in that respect. Specifically, in this embodiment, the intermediate portion 332 disposed between the adjacent light transmission portions 31 has a light reflection layer 332 a at the interface with the light transmission portion 31. And the light absorption part 332b is formed in the space | interval part 332 between this light reflection layer 332a.

The light reflecting layer 332a is a layer for reflecting light using reflection from a metal surface or other material surface, and is formed at the interface with the light transmitting portion 31 in the intermediate portion 332. The light reflecting layer 332a can be formed of a deposited film of aluminum, copper, silver, or the like, for example.
The light absorbing portion 332b may be formed following the light absorbing portion 32 described above.

  According to such an optical function layer 330, the light incident on the optical function layer 330 is basically collected by the prism layer 28. Therefore, for example, as indicated by L 81 in FIG. The light transmission part 31 is transmitted without reaching the interface. Alternatively, as indicated by L <b> 82 in FIG. 8, even when the light reaches the interface between the light transmission part 31 and the intermediate part 332, it can be reflected by the light reflection layer 332 a and transmitted through the light transmission part 31. In this embodiment, since the reflection is not based on the total reflection, even the light that does not satisfy the total reflection condition can be reflected by the light reflection layer 332a and emitted. Thereby, it is possible to emit light brighter. On the other hand, part of light transmitted through the light reflecting layer 332a and light incident on the intermediate portion 332 from the light exit surface side (above the paper surface in FIG. 8) are absorbed by the light absorbing portion 332b.

  FIG. 9 is a diagram for explaining the fifth embodiment and corresponds to FIG. In this embodiment, an optical sheet 426 is applied instead of the optical sheet 26, and the other configurations are the same as those of the video source unit 10.

  The optical sheet 426 includes a base material layer 27 and a prism layer 28 (not shown in FIG. 9) as with the optical sheet 26, but includes an optical functional layer 430 instead of the optical functional layer 30. This is different from the optical sheet 26 in that respect. Specifically, the intermediate portion 432 disposed between the adjacent light transmission portions 31 has a light reflection layer 432 a at the interface with the light transmission portion 31. A transparent portion 432b which is transparent while being sandwiched between the light reflecting layers 332a is formed.

The light reflecting layer 432a is a layer for reflecting light by utilizing reflection from a metal surface or other material surface, and is formed at the interface with the light transmitting portion 31 in the intermediate portion 432. The light reflecting layer 432a can be formed of a deposited film of aluminum, copper, silver, or the like, for example.
The transparent portion 432b may be formed so as to transmit light by being filled with a cavity or a transparent resin.

According to such an optical function layer 430, the light incident on the optical function layer 430 is basically collected by the prism layer 28. Therefore, for example, as shown by L91 in FIG. The light transmissive part 31 is transmitted without reaching the interface with the intermediate part 432. Alternatively, as indicated by L <b> 92 in FIG. 9, even if the light reaches the interface with the intermediate portion 432, it can be reflected by the light reflecting layer 432 a and transmitted through the light transmitting portion 31. In this embodiment, since the reflection is not based on the total reflection, even the light that does not satisfy the total reflection condition can be reflected by the light reflection layer 432a to be emitted, and the light can be emitted more brightly.
Further, in the optical function layer 430, as indicated by L93, the light incident on the transparent portion 432b of the intermediate portion 432 from the light exit surface side (above the paper surface in FIG. 9) is repeatedly reflected on the inner side of the intermediate portion 432, and on the light exit side. Emitted. This makes it possible to provide brighter light.

The surface light source device may be provided with a light diffusion layer. FIG. 10 is a diagram for explaining the sixth embodiment. This figure corresponds to FIG. FIG. 11 is a cross section of the light diffusion layer 536 in the direction in which the unit prism 29 of the prism layer 28 extends (the direction orthogonal to the light guide direction of the light guide plate 22).
In this embodiment, it is an image source unit 510 to which a surface light source device 520 is applied instead of the surface light source device 20. In the image source unit 510, a light diffusion layer 536 is provided on the light exit surface side of the light guide plate 22. Since the configuration other than the light diffusion layer 536 is the same as that of the surface light source device 20, the light diffusion layer 536 will be described here. That is, also in this embodiment, the optical sheet 26 is directly laminated with an adhesive on the lower polarizing plate.

The light diffusion layer 536 of this embodiment is a diffusion layer provided on the light exit surface of the light guide plate 21, and unit diffusion elements 536 a that are a plurality of convex portions are arranged. It is a diffusion layer having anisotropic diffusivity that diffuses light in a predetermined direction.
The unit diffusing element 536a is a columnar element having a prism-shaped cross section having a pentagonal cross section as shown in FIG. 11 and having the ridge line extending in one while maintaining the cross section. The direction in which the ridge line of the unit diffusing element 536a extends is orthogonal to the direction orthogonal to the direction in which the ridge line of the unit back surface prism 23a extends, and the direction in which the light transmission part 31 and the light absorption part 32 of the optical function layer 30 extend. Direction. That is, the unit diffusion element 536 a has a ridge line parallel to the light guide direction of the light guide plate 21.

The unit diffusing element 536a of the present embodiment has a pentagonal cross section that can diffuse and emit the light incident thereon, and the specific shape is particularly if it is configured to have a diffusing action in this way. There is no limit. That is, as represented by an optical path example L111 in FIG. 11, the light emitted from the light guide plate 21 and incident on the unit diffusing element 536a is normal to the light guide plate by the inclined surface when emitted from the unit diffusing element 536a. The direction is changed to a direction more inclined with respect to the direction (the line indicated by _nd in FIG. 11), that is, the diffusion direction, thereby exhibiting a diffusion action.

  According to the light diffusion layer 536, the light emitted from the light guide plate 22 can be diffused to further uniform the light. Although the light diffusion layer of the example having a pentagonal cross section as described above is shown in this embodiment, other cross-sectional shapes can be given as long as light can be diffused. For example, a prism shape having a triangular cross section, a light diffusing layer 546 ′ having a unit diffusing element 536′a having a lenticular lens shape (semicircular convex cross section) shown in FIG. 12A, and FIG. Mention may be made of the light diffusion layer 536 "having unit diffusion elements 536" a in the form of a semicircular concave cross section as shown.

  The light diffusion layer described above is a light diffusion layer having the property of anisotropic diffusion that diffuses light in the direction orthogonal to the direction in which the unit diffusion elements extend. On the other hand, a light diffusion layer having the property of isotropic diffusion that diffuses light isotropically may be provided. Examples of such a light diffusing layer include a transparent resin binder in which transparent fine particles having a refractive index different from that of the binder are dispersed and a so-called mat surface having minute irregularities on the surface. it can.

  Further, in the present embodiment, the example in which the light diffusion layer is disposed on the light output side of the light guide plate is described, and the example in which the light diffusion layer is disposed between the light guide plate and the prism layer is described. However, the present invention is not limited to this, and it may be disposed between the prism layer and the optical function layer on the light incident side of the optical function layer, or may be disposed on the light output side of the optical function layer.

DESCRIPTION OF SYMBOLS 10 Image source unit 15 Liquid crystal panel 20 Surface light source device 21 Light guide plate 25 Light source 26 Optical sheet 28 Optical element layer (prism layer)
30 Optical functional layer 31 Light transmission part 32 Light absorption part (interspace part)
126, 226, 326, 426, optical sheet 332, 432 portion 332 a, 432 a light reflection layer 235 reflection type polarizing film 536 light diffusion layer

Claims (19)

An image source unit comprising: a surface light source device having a light source; and a liquid crystal panel disposed on a light output side of the surface light source device,
The surface light source device includes an optical sheet that transmits light from the light source and emits light to the liquid crystal panel,
The optical sheet is
An optical functional layer that is adhered to the lower polarizing plate of the liquid crystal panel and arranged in the thickness direction of the optical sheet, and an optical element layer,
The optical functional layer is
A light transmissive portion having a predetermined cross section and extending in one direction and arranged in a direction different from the extending direction at a predetermined interval;
A space formed at the interval between the plurality of light transmission portions, and
The optical element layer is
A plurality of unit optical elements having a cross section that is convex on the side opposite to the optical functional layer and extending in one direction having the cross section are arranged in a direction different from the extending direction.
Video source unit.   2. The video source unit according to claim 1, wherein the one direction in which the light transmission part extends and the one direction in which the unit optical element extends have an angle formed by a front view of the optical sheet of 10 ° or less.   The video source according to claim 1, further comprising: a base material layer, wherein the optical functional layer is laminated on one surface of the base material layer, and the optical element layer is laminated on the other surface of the base material layer. unit.   4. The optical function layer according to claim 1, wherein the light transmitting portion of the optical function layer has a trapezoidal cross section, and a long lower bottom of the trapezoidal cross section faces the optical element layer side. The video source unit described in 1.   4. The optical function layer according to claim 1, wherein the light transmitting portion of the optical function layer has a trapezoidal cross section, and a short upper base of the trapezoidal cross section faces the optical element layer side. The video source unit described in 1.   The video source unit according to claim 1, further comprising a reflective polarizing film.   The image source unit according to claim 6, wherein the reflective polarizing film is disposed between the optical functional layer and the optical element layer.   The video source unit according to claim 1, further comprising a light diffusion layer.   9. The video source unit according to claim 8, wherein the light diffusion layer is a light diffusion layer that performs anisotropic light diffusion.   9. The image source unit according to claim 8, wherein the light diffusion layer has a prism or lenticular lens shape.   The image source according to claim 10, wherein a direction in which the prism or the lenticular lens extends is an angle that forms 90 ° in a front view of the optical sheet with respect to the one direction in which the transmission portion of the optical functional layer extends. unit.   The image source unit according to claim 8, wherein the light diffusion layer is disposed on the opposite side of the optical functional layer with the optical element layer interposed therebetween.   12. The image source unit according to claim 8, wherein the light diffusion layer is disposed on the opposite side of the optical element layer with the optical function layer interposed therebetween.   The image source unit according to claim 8, wherein the light diffusion layer is disposed between the optical functional layer and the optical element layer.   The video source unit according to claim 1, wherein a refractive index of the intermediate portion is smaller than a refractive index of the light transmission portion.   The image source unit according to claim 1, wherein a layer that reflects light is formed at an interface with the light transmission portion at the intermediate portion.   The video source unit according to claim 1, wherein a material that absorbs light is contained in the space.   The image source unit according to claim 1, wherein the light source is disposed on a side of the optical element layer on the optical element layer where the unit optical element is convex. Video source unit according to claim 1 to 18,
And a housing for housing the video source unit.

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