JP2013003321A - Lens sheet, surface light source device and transmission type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens sheet capable of displaying satisfactory 3D-images by eliminating problems such as non-uniformity of the brightness in a right-left direction of a screen and a decrease in visibility of 3D-images, and a surface light source device and a transmission type display device including the same.SOLUTION: A lens sheet 14 is configured so that each of unit prisms 142 formed on a prism layer 143 on the incident side has a shape of generally triangular prism; plural unit prisms are disposed in a direction parallel to a disposition direction of unit lenses 144 each having a generally cylindrical shape formed on a lens layer 145 on the light-emitting side; at the center in the disposition direction of the unit lenses 144, the positions of the vertices of the unit prisms 142 and the corresponding unit lenses 144 are identical to each other viewing a from a normal direction of the sheet plane; and the vertices of the unit prisms 142 are positioned closer to the end portion than the vertices 144 t of the unit lenses 144 toward the edge portion from the center in the disposition direction of the unit lens 144.

Description

  The present invention relates to a lens sheet, a surface light source device including the lens sheet, and a transmissive display device.

In recent years, demand for display devices capable of displaying stereoscopic images has increased.
As a method for displaying a stereoscopic image, for example, left-eye image light and right-eye image light having parallax are converted into linearly polarized light having different polarization planes, and the images reach each eye using polarized glasses. Switching between images that allow the left and right eyes to be viewed with observation glasses so that left-eye video and right-eye video with parallax displayed in a time-sharing manner reach the left and right eyes of the observer, respectively. There is. However, in such a display device using glasses, there are cases where an observer feels troublesome to wear the glasses.

  Thus, for example, a display device that can observe a stereoscopic image with the naked eye, such as the display device disclosed in Patent Document 1, has been developed. In the display device disclosed in Patent Literature 1, left and right eye images are emitted in predetermined directions by a double-sided prism sheet provided between an LCD (Liquid Crystal Display) panel and a light guide plate. This double-sided prism sheet has a triangular prism lens array on the incident side, is arranged in the same direction as the triangular lens array on the output side, has the same pitch as the triangular lens array, and is formed at a position corresponding to the triangular prism lens It has a lens array.

Japanese Patent No. 3930021

  However, in such a three-dimensional image display device using a double-sided prism sheet, a clear three-dimensional image can be observed in the central portion of the observation screen in the arrangement direction of the triangular prism and the cylindrical lens. On the part side, there is a problem that the image becomes dark and the three-dimensional image becomes unclear.

  An object of the present invention is to improve a non-uniform brightness in the horizontal direction of the screen and a decrease in the visibility of a 3D image and the like, a lens sheet capable of displaying a good 3D image, a surface light source device including the lens sheet, and a transmission type It is to provide a display device.

The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.
According to the first aspect of the present invention, a transmissive display unit of a transmissive display device capable of displaying a stereoscopic image by alternately emitting right-eye image light and left-eye image light in a predetermined direction is irradiated from the back side. A lens sheet that is used in a surface light source device and has an optical shape formed on both sides thereof, and a sheet-like base material layer (141) and a substantially cylindrical partial shape on the emission side of the base material layer or A lens layer (145) formed by arranging a plurality of convex unit lenses (144) that are part of a substantially elliptical column shape, and a convex unit prism (142, 142) on the incident side of the base material layer 242) and a prism layer (143, 243) formed by arranging a plurality of the unit prisms, each having a substantially triangular prism shape, and a plurality of unit prisms arranged in a direction parallel to the arrangement direction of the unit lenses. One unit lens through the material layer The unit prisms correspond to each other, and at the center in the arrangement direction of the unit lenses, the unit prisms and the corresponding unit lenses correspond to the vertexes (142t) when viewed from the normal direction of the sheet surface. , 144t, 242t) coincide with each other, and as the unit lenses move from the center to the end in the arrangement direction, the apexes (142t, 242t) of the unit prism gradually become closer to the apexes (144t) of the unit lenses. The amount of deviation (Δx) in the arrangement direction of the unit lenses between the apex of the unit lenses and the apex of the unit prism corresponding to the unit lens when viewed from the normal direction of the sheet surface. ) Is a lens sheet (14, 24) characterized by gradually increasing.

According to a second aspect of the present invention, in the lens sheet of the first aspect, the arrangement pitch (P2) of the unit prisms (142, 242) is larger than the arrangement pitch (P4) of the unit lenses (144). It is a lens sheet (14, 24) characterized by these.
According to a third aspect of the present invention, in the lens sheet according to the first aspect, the arrangement pitch of the unit prisms is constant, and the arrangement pitch of the unit lenses gradually increases from the center toward both ends in the arrangement direction. The lens sheet is characterized in that the lens sheet becomes smaller.
According to a fourth aspect of the present invention, in the lens sheet according to any one of the first to third aspects, the vertexes (142t, 242t) of the unit prisms (142, 242) are The lens sheet (14, 24) is characterized by being positioned within the lens width of the unit lens (144) corresponding to the unit prism.
According to a fifth aspect of the present invention, in the lens sheet according to any one of the first to fourth aspects, the side surfaces (242a, 242b) of the unit prism (242) are concave curved surfaces. The lens sheet (24).
According to a sixth aspect of the present invention, in the lens sheet according to the fifth aspect, the vertex (242t) of the unit prism (242) is parallel light from the unit lens side at the center in the arrangement direction of the unit lenses (144). It is a lens sheet (24) characterized by being located in the base material layer side in the thickness direction of this lens sheet rather than the focal position of the parallel light at the time of irradiation.
The invention according to claim 7 is the lens sheet according to any one of claims 1 to 6, wherein the unit prism (14, 24) is made of an ionizing radiation curable resin. It is a lens sheet.

The invention according to an eighth aspect is the lens sheet (14, 24) according to any one of the first to seventh aspects, and the prism layer (143, 243) side with respect to the lens sheet. The light source plate (13) and the first light source unit (12A) and the second light source unit (12A) respectively disposed at positions facing both end surfaces (13a, 13b) of the light guide plate in the arrangement direction of the unit prisms. 12B) is a surface light source device (12A, 12B, 13, 14, 24).
The invention of claim 9 comprises the surface light source device (12A, 12B, 13, 14, 24) according to claim 8, and a transmissive display unit (11) illuminated from the back side by the surface light source device. The first light source unit (12A) and the second light source unit (12B) are alternately turned on and off, and the transmissive display unit is turned on when the first light source unit is turned on. When the second light source unit is turned off, the right eye image is displayed. When the second light source unit is turned on and the first light source unit is turned off, the left eye image is displayed. A transmissive display device (10) characterized in that a video to be displayed is switched in synchronization with turning on and off of one light source unit and the second light source unit.

(1) The lens sheet according to the present invention has a substantially triangular prism shape on the incident side of the base material layer and has a plurality of unit prisms arranged in a direction parallel to the arrangement direction of the unit lenses. One unit prism corresponds to one unit lens. At the center of the unit lens arrangement direction, the unit prism and the corresponding unit lens have the same apex position when viewed from the normal direction of the sheet surface, and the unit lens is arranged from the center to the end in the arrangement direction. As it goes, the vertex of the unit prism is gradually located closer to the end of the unit lens than the vertex of the unit lens, and when viewed from the normal direction of the sheet surface, the vertex of the unit lens and the unit prism corresponding to the unit lens The amount of deviation in the arrangement direction of the unit lenses from the apex gradually increases.
Therefore, the light incident on the vicinity of the top of the unit prism can be raised in a predetermined direction on the viewer side, and the right and left eye image light is alternately directed to the predetermined direction in the lens sheet. By using a surface light source device of a transmissive display device that can display a stereoscopic image by emitting each, it is possible to deliver video light for the right eye to the right eye and deliver video light for the left eye to the left eye, A good stereoscopic image can be provided to an observer. Then, when viewed from the front side of the lens sheet, in the arrangement direction of the unit prism and unit lenses, the luminance is non-uniformity in which both ends are dark and the center is bright, and the three-dimensional images at both ends are incomplete. It can improve the degradation of video quality.

(2) Since the arrangement pitch of the unit prisms is larger than the arrangement pitch of the unit lenses, the vertexes of the unit prisms become more outward (ends with respect to the vertexes of the unit lenses) toward the both ends along the arrangement direction of the unit prisms. Part side). Therefore, the light incident on the vicinity of the top of the unit prism can be raised in a predetermined direction on the viewer side, and the right and left eye image light is alternately directed to the predetermined direction in the lens sheet. By using a surface light source device of a transmissive display device that can display a stereoscopic image by emitting each, it is possible to deliver video light for the right eye to the right eye and deliver video light for the left eye to the left eye, A good stereoscopic image can be provided to an observer. Then, when viewed from the front side of the lens sheet, in the arrangement direction of the unit prism and unit lenses, the luminance is non-uniformity in which both ends are dark and the center is bright, and the three-dimensional images at both ends are incomplete. It can improve the degradation of video quality.

(3) The arrangement pitch of the unit prisms is constant, and the arrangement pitch of the unit lenses gradually decreases in the arrangement direction from the center toward both ends, so that the vertex of the unit prism is smaller than the vertex of the unit lens. Therefore, it will be located on the outer side (end side). Therefore, the light incident on the vicinity of the top of the unit prism can be raised in a predetermined direction on the viewer side, and the right and left eye image light is alternately directed to the predetermined direction in the lens sheet. By using a surface light source device of a transmissive display device that can display a stereoscopic image by emitting each, it is possible to deliver video light for the right eye to the right eye and deliver video light for the left eye to the left eye, A good stereoscopic image can be provided to an observer. Then, when viewed from the front side of the lens sheet, in the arrangement direction of the unit prism and unit lenses, the luminance is non-uniformity in which both ends are dark and the center is bright, and the three-dimensional images at both ends are incomplete. It can improve the degradation of video quality.

(4) Since the vertex of the unit prism is located within the lens width of the unit lens corresponding to the unit prism in the arrangement direction, most of the light incident on the unit prism is from the unit lens corresponding to the unit prism. The light incident on the lens sheet can be emitted in a predetermined direction, and stray light can be reduced.

(5) Since the side surface of the unit prism is a concave curved surface, it is possible to launch light to the viewer even when the accuracy of the shape and dimensions near the apex of the unit prism is not so high.

(6) The vertex of the unit prism is located at the base layer side in the thickness direction of the lens sheet from the focal position of the parallel light when the parallel light is irradiated from the unit lens side at the center in the arrangement direction. Since the unit prism has a concave curved side surface, the light incident on the unit prism can be efficiently raised to the emission side and emitted in a predetermined direction. Even if it is located on the side, the light incident on the unit prism can be efficiently launched to the exit side.

(7) Since the unit prism is made of ionizing radiation curable resin, it is easy to manufacture.

(8) The lens sheet according to the present invention, the light guide plate disposed on the prism layer side with respect to the lens sheet, and the first light source disposed at positions facing both end faces of the light guide plate in the arrangement direction of the unit prisms. And a second light source unit, the light from each light source unit can be emitted alternately in a predetermined direction, and the screen position when viewed from the front direction. Therefore, the surface light source device with high brightness uniformity can be obtained.

(9) A surface light source device according to the present invention and a transmission type display unit illuminated from the back side by the surface light source device, wherein the first light source unit and the second light source unit are alternately turned on and off, The transmissive display unit displays an image for the right eye when the first light source unit is turned on and the second light source unit is turned off, and the second light source unit is turned on and the first light source unit is turned off. In this case, the display device is a transmissive display device that displays an image for the left eye and switches the image to be displayed in synchronization with turning on and off of the first light source unit and the second light source unit. Therefore, the observer can display a three-dimensional image that can be observed without using glasses or the like that control the viewing of the left and right eye images. In addition, it is possible to effectively reduce luminance reduction and crosstalk that tend to occur at both ends in the left-right direction of the screen, and provide a good stereoscopic image to the viewer.

It is a figure explaining the display apparatus and surface light source device of 1st Embodiment. It is a figure explaining the shape of the lens sheet of 1st Embodiment. It is a figure which shows the shift | offset | difference of the position of the vertex of a unit prism with respect to the vertex of a unit lens in an arrangement direction, and the emitted light intensity distribution from a lens sheet. It is a figure which shows the shift | offset | difference of the position of the vertex of a unit prism with respect to the vertex of a unit lens in an arrangement direction, and the emitted light intensity distribution from a lens sheet. It is a figure which shows the shift | offset | difference of the position of the vertex of a unit prism with respect to the vertex of a unit lens in an arrangement direction, and the emitted light intensity distribution from a lens sheet. It is a figure which shows the mode of the light in each part of the screen left-right direction of the lens sheet of 1st Embodiment. It is a figure which shows the emission direction of the light in the display apparatus of 1st Embodiment, and the display apparatus of a comparative example. It is a figure explaining the shape of the lens sheet of 2nd Embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
In addition, each figure shown below including FIG. 1 is the figure shown typically, and the magnitude | size and shape of each part are exaggerated suitably for easy understanding.
In addition, the terms “plate”, “sheet”, “film” and the like are used, but these are generally used in the order of thickness, “plate”, “sheet”, “film”. I am using it. However, since there is no technical meaning in such proper use, the description in the claims is used in the unified description of the sheet. Accordingly, the terms “sheet”, “plate”, and “film” can be appropriately replaced. For example, the optical sheet may be an optical film or an optical plate.
Furthermore, numerical values such as dimensions and material names of each member described in the present specification are examples of the embodiment, and the present invention is not limited thereto, and may be appropriately selected and used.

(First embodiment)
FIG. 1 is a diagram illustrating a display device and a surface light source device according to the first embodiment.
The display device 10 includes an LCD panel 11, light source units 12A and 12B, a light guide plate 13, a lens sheet 14, and a control unit 15, and illuminates and displays an image displayed on the LCD panel 11 from the back. It is a transmissive liquid crystal display device. The display device 10 is a stereoscopic video display device that allows the observer O to observe a stereoscopic video without using stereoscopic glasses or the like.
The surface light source device (backlight) of the display device 10 is an edge ride type, and in the present embodiment, the light source units 12A and 12B, the light guide plate 13, and the lens sheet 14 correspond.

The LCD panel 11 is a transmissive display unit including a transmissive liquid crystal display element. The LCD panel 11 of the present embodiment has, for example, a substantially rectangular shape with a screen size of 2.8 inches diagonal, and can display a resolution of 320 × 240 pixels. The LCD panel 11 has a plurality of sub-pixels arranged in a matrix. Each of the sub-pixels displays primary colors of red (R), green (G), and blue (B), and three sub-pixels of R, G, and B constitute one pixel (pixel) as one set. Yes. In the present embodiment, one pixel has a substantially square shape and is arranged in the horizontal direction of the screen and the vertical direction of the screen. One pixel is divided into three in the horizontal direction of the screen, and R, G, and B subpixels are arranged. The arrangement pitch of the pixels is about 178 μm, and the arrangement pitch of the sub-pixels in the horizontal direction of the screen is about 59 μm. Note that the present invention is not limited to the above example, and one pixel may be composed of three or more subpixels.
The LCD panel 11 alternately displays a right-eye image and a left-eye image, which are two parallax images having parallax, according to an instruction from the control unit 15.

  In the following specification, as an example, the direction parallel to the short side of the observation screen (LCD panel 11) in the usage state of the display device 10 is the screen vertical direction (screen vertical direction) in the usage state, and is parallel to the long side. The direction is the left-right direction of the screen in the use state (the horizontal direction of the screen). In FIG. 1, a cross section parallel to the horizontal direction of the screen of the display device 10 is shown. In the following description, unless otherwise specified, it is assumed that the screen horizontal direction and the screen vertical direction are the screen horizontal direction and the screen vertical direction when the display device 10 is used.

The light source units 12A and 12B are portions that emit light that illuminates the LCD panel 11. The light source parts 12A and 12B are provided at positions facing both end faces 13a and 13b of the light guide plate 13 in the horizontal direction of the screen. The light source units 12A and 12B are alternately turned on and off according to instructions from the control unit 15. The light sources 12A and 12B are turned on and off in synchronization with the switching of the display image on the LCD panel 11.
The light source units 12A and 12B according to the present embodiment use a light emitting diode (LED) that emits white light as a light source, and extend in the vertical direction of the screen along both horizontal ends of the light guide plate 13 (not shown). Used in combination with a guide.

The light guide plate 13 is a member that guides light emitted from the light source units 12A and 12B. As shown in FIG. 1, light source sections 12 </ b> A and 12 </ b> B are arranged at positions facing the two end faces 13 a and 13 b of the light guide plate 13 facing each other in the arrangement direction of the unit lenses 144 and the unit prisms 142.
The light guide plate 13 of the present embodiment is made of acrylic resin, but is not limited to this, and for example, a product made of PC (polycarbonate) resin or the like may be appropriately selected and used.
The light guide plate 13 is formed with dots (not shown) having a diffusing action by printing or the like on the back surface 13d. The light guide plate 13 may be subjected to a roughening process or the like on the exit-side surface 13c.
A reflection plate (not shown) or the like may be provided on the back side of the light guide plate 13 (the side opposite to the lens sheet 14). The reflecting plate is a member that can reflect light and reflects the light reflected toward the light guide plate 13 by the lens sheet 14 or the like and directs the light toward the lens sheet 14 again. By providing such a reflector, the light from the light source unit can be used more efficiently.

The lens sheet 14 includes a base material layer 141, a prism layer 143 formed on the incident side (light guide plate 13 side) surface of the base material layer 141, and an output side (LCD panel 11 side) surface of the base material layer 141. And a lens layer 145 formed on the substrate. The prism layer 143 has a plurality of unit prisms 142 arranged, and the lens layer 145 has a plurality of unit lenses 144 arranged in a direction parallel to the arrangement direction of the unit prisms 142.
The lens sheet 14 emits light incident on the unit prism 142 on the incident side (light guide plate 13 side) in a direction that reaches the left and right eyes of the observer O located in the substantially front direction from the unit lens 144. At the center in the arrangement direction (left-right direction of the screen), the lens sheet 14 is an observer O positioned substantially in the front direction with respect to the observation surface (sheet surface of the lens sheet 14) of the display device 10 as shown in FIG. , The light La from the light source unit 12A is emitted to the right side in the horizontal direction of the screen with respect to the normal direction of the sheet surface, and the light Lb from the light source unit 12B is left in the horizontal direction of the screen with respect to the normal direction of the sheet surface. To exit. In the present embodiment, in the emission intensity distribution with respect to the sheet surface in the horizontal direction of the screen, the half-value angle of the peak intensity of the light La is 0 to 15 ° on the right side of the horizontal direction of the screen, and the half-value angle of the peak intensity of the light Lb is The lens sheet 14 is designed to be 0 to 15 ° on the left side in the direction.

FIG. 2 is a diagram illustrating the shape of the lens sheet 14 according to the first embodiment. FIG. 2A shows a cross section orthogonal to the sheet surface of the lens sheet 14 and parallel to the arrangement direction of the unit prism 142 and the unit lens 144 (the horizontal direction of the screen). FIG. 2B is an enlarged view of one end portion in the arrangement direction (right end portion in the left-right direction of the screen when viewed from the observer O) in the cross section of FIG. 2A. 2A is an enlarged view of the center in the arrangement direction (the center in the horizontal direction of the screen) in the cross section of FIG. 2A, and FIG. 2D is the other end portion in the arrangement direction (observation) in the cross section of FIG. It is an enlarged view of a screen left-right direction left end portion as viewed from the person O.
The sheet surface indicates, for example, a surface of the lens sheet 14 that is the planar direction of the lens sheet 14 when viewed as the entire lens sheet 14, and in the present specification and claims. Are also used as the same definition. Further, the sheet surface of the lens sheet 14 is parallel to the observation surface of the display device 10 (LCD panel 11).

The base material layer 141 is a layer that serves as a base (base material) of the lens sheet 14, and uses a sheet-like member having optical transparency. A prism layer 143 is formed on the incident side (light guide plate 13 side) of the base material layer 141, and a lens layer 145 is formed on the output side (LCD panel 11 side) of the base material layer 141.
The base material layer 141 of the present embodiment uses a sheet-like member made of a thermoplastic resin having optical transparency. The thickness of the base material layer 141 is T.

The lens layer 145 is a layer formed on the exit side (LCD panel 11 side) surface of the base material layer 141, and a plurality of unit lenses 144 are arranged on the exit side surface along the sheet surface in the horizontal direction of the screen. ing.
The unit lens 144 is a so-called cylindrical lens having a substantially cylindrical partial shape. The unit lens 144 has a function of emitting light emitted from the light source units 12A and 12B, guided through the light guide plate 13 and incident on the lens sheet 14 in a predetermined direction depending on the shape thereof. .
The unit lens 144 has a constant shape regardless of the position in the arrangement direction (left-right direction of the screen) of the unit lenses 144, and the arrangement pitch is P4. From the viewpoint of displaying a clear stereoscopic image and further improving the effect of reducing display defects such as a muscular feeling and moire of the image, the arrangement pitch P4 of the unit lenses 144 and the arrangement pitch P2 of the unit prisms 142 to be described below are LCDs. More preferably, it is smaller than the arrangement pitch of the sub-pixels of panel 11 in the horizontal direction of the screen.

The prism layer 143 is formed on the incident side (light guide plate 13 side) surface of the base material layer 141, and a plurality of unit prisms 142 are arranged on the incident side surface in the horizontal direction of the screen along the sheet surface. Yes. The arrangement direction of the unit prisms 142 is parallel to the arrangement direction of the unit lenses 144.
The unit prism 142 has a substantially isosceles triangular prism shape. The cross-sectional shape of the cross section of the unit prism 142 that is parallel to the horizontal direction of the screen and orthogonal to the sheet surface is a substantially isosceles triangular shape, and the lengths of the sides corresponding to the side surfaces 142a and 142b in the cross-sectional shape are equal.
The unit prism 142 has a constant shape regardless of the position in the arrangement direction (left-right direction of the screen), and the arrangement pitch P2 is larger than the arrangement pitch P4 of the unit lenses.

As shown in FIG. 2C, the vertex 142t of the unit prism 142 coincides with the vertex 144t of the unit lens 144 when viewed from the normal direction of the sheet surface at the center in the arrangement direction (the center in the horizontal direction of the observation screen). The virtual straight line H that is orthogonal to the sheet surface and passes through the vertex 144t of the unit lens 144 passes through the vertex 142t of the unit prism 142.
However, since the arrangement pitch P2 of the unit prisms 142 is larger than the arrangement pitch P4 of the unit lenses, the vertex 144t of the unit lens 144 and the vertex 142t of the unit prism 142 are arranged at the center of the unit lens 144 and the unit prism 142 in the arrangement direction. Are coincident when viewed from the normal direction of the sheet surface, but the positions of the unit prism 142 and the unit lens 144 gradually shift toward the end side (outside) toward the end side in the arrangement direction. As the unit lens 144 and the unit prism 142 are arranged in the arrangement direction from the center toward the end side, the deviation amount in the arrangement direction between the unit prism apex 142t and the corresponding unit lens 144 apex 144t gradually increases. .

As shown in FIG. 2B, the apex 142t gradually increases with respect to a straight line H that passes through the apex 144t of the unit lens and is orthogonal to the sheet surface as viewed from the observer O toward the right end of the screen in the left-right direction. It will be located on the right side of the screen. The amount of deviation Δx between the apex 144t of the unit lens 144 and the apex 142t of the unit prism 142 in the arrangement direction (left-right direction of the screen) increases toward the right side in the left-right direction of the screen when viewed from the observer O.
Further, as shown in FIG. 2D, the vertex 142t gradually increases with respect to a straight line H passing through the vertex 144t of the unit lens and orthogonal to the sheet surface as viewed from the observer O toward the left side of the screen. It will be located on the left side of the screen. Then, the amount of deviation Δx between the apex 144t of the unit lens 144 and the apex 142t of the unit prism 142 in the arrangement direction (left-right direction of the screen) increases as it goes to the left in the left-right direction of the screen as viewed from the observer O.

  Each of the unit prisms 142 has a one-to-one correspondence with the unit lens 144 at a position facing each other with the base material layer 141 therebetween, and the vertex of the unit prism 142 is seen from the normal direction of the sheet surface. 142t is not located outside the lens width of the unit lens 144 corresponding to the unit prism 142. That is, the vertex 142 t of the unit prism 142 is located within the lens width of the unit lens 144 corresponding to the unit prism 142.

The apex 142t of the unit prism 142 located at the center in the arrangement direction of the unit prisms 142 is substantially equal to the virtual focal point of the unit lens 144 in the thickness direction of the lens sheet 14 (the normal direction of the sheet surface). The focal point is when the incident side of the base material layer 141 is covered with a resin that forms the unit prism 142 with a sufficient thickness and when parallel light is irradiated from the unit lens 144 side in a direction perpendicular to the sheet surface. In addition, it is a point that becomes the focal point (condensing point) of the substantially parallel light.
The unit prism 142 (prism layer 143) of this embodiment is made of an ultraviolet curable resin. The unit lens 144 is not limited to the ultraviolet curable resin, and may be another ionizing radiation curable resin such as an electron beam curable resin.

  As an example of the lens sheet 14 of the present embodiment, for example, a lens sheet 14 having the following dimensions can be used. The lens sheet 14 of the embodiment has an arrangement pitch P4 of unit lenses 144 = about 70 μm, a radius of curvature of about 50 μm, and a land thickness of about 10 μm. Further, the thickness of the base material layer 141 is T = 38 μm. Further, the unit prism 142 has a prism height (a dimension in the thickness direction from the valley bottom between the unit prisms 142 to the apex 142t) of about 60 μm, a land thickness of about 10 μm, and an apex angle of about 60 μm. °. In addition, the arrangement pitch P2 of the unit prisms 142 is macroscopically substantially the same as the arrangement pitch P4 of the unit lenses 144, but in the implementation, the arrangement pitch of the unit lenses 144 is such that it is difficult to measure the difference. Slightly larger than P4. The ratio Δx / P of the deviation Δx between the apex 142t and the apex 144t in the arrangement direction of the unit lenses 144 and the unit prisms 142 to the arrangement pitch P4 of the unit lenses 144 is Δx at the center of the arrangement direction (the horizontal direction of the screen). / P4 = 0 (ie, Δx = 0), and Δx / P4 = about 0.15 at both ends.

Returning to FIG. 1, the control unit 15 alternately switches the light emission of the light source units 12 </ b> A, 12 </ b> B, and synchronizes with the light emission of the light source units 12 </ b> A, 12 </ b> B. Instructs to switch to the video. That is, according to an instruction from the control unit 15, for example, when the light source unit 12B is turned off and the light source unit 12A emits light, the LCD panel 11 displays an image for the right eye, and the light source unit 12A is turned off and the light source unit 12B emits light. When this is done, the LCD panel 11 displays the image for the left eye.
The control unit 15 of this embodiment instructs the switching of the display image on the LCD panel 11 and the alternate light emission of the light source units 12A and 12B while synchronizing at a predetermined frequency. This frequency may be appropriately set according to the characteristics of the LCD panel 11 to be used, the usage environment, and the like.

A method for displaying a stereoscopic image of the display device 10 according to the present embodiment will be described.
In the display device 10 shown in FIG. 1, for example, the light emitted from the light source unit 12 </ b> A travels through the light guide plate 13, exits from the exit-side surface 13 c of the light guide plate 13, and one of the unit prisms 142 of the lens sheet 14. Incident on the side surface 142a.
The light incident on the unit prism 142 is totally reflected by the side surface 142b facing the side surface 142a and travels toward the unit lens 144 side. Then, the light exits from the unit lens 144 toward the right eye side of the observer O positioned substantially in the front direction and enters the LCD panel 11. At this time, since the LCD panel 11 displays the right-eye image, the light of the right-eye image reaches the right eye of the observer O. On the other hand, since the light source unit 12B is turned off, the amount of light reaching the left eye is very small and does not affect the viewing of the stereoscopic video.

The light emitted from the light source unit 12 </ b> B is guided through the light guide plate 13, exits from the exit-side surface 13 c of the light guide plate 13, and enters one side 142 b of the unit prism 142 of the lens sheet 14. The incident light is totally reflected by the opposing side surface 142a and travels toward the unit lens 144 side. Then, the light is emitted from the unit lens 144 toward the left eye side of the observer O positioned substantially in the front direction and enters the LCD panel 11. At this time, since the LCD panel 11 displays the left-eye image, the light of the left-eye image reaches the left eye of the observer O. On the other hand, since the light source unit 12A is turned off, the amount of light reaching the right eye is very small and does not affect the viewing of the stereoscopic video.
Therefore, the right eye image reaches the right eye of the observer O, the left eye image arrives at the left eye, and these are switched at high speed. Therefore, the observer O can stereoscopically view with the naked eye by these parallax images. Yes, you can observe 3D images.

Here, the positional shift in the arrangement direction of the vertex 142t of the unit prism 142 with respect to the vertex 144t of the unit lens 144 and the operation thereof will be described.
FIGS. 3 to 5 are diagrams showing the positional deviation of the vertexes of the unit prisms with respect to the vertexes of the unit lenses in the arrangement direction and the emission intensity distribution of light from the lens sheet. 3 to 5, the vertical axis represents the relative intensity, the light emission intensity ratio when the peak intensity is 1, and the horizontal axis represents the emission angle with respect to the sheet surface in the horizontal direction of the screen. The right side in the left-right direction of the screen viewed from the observer O and the negative direction are the left side in the left-right direction of the screen of the observer O.
3 to 5 show the light when an evaluation lens sheet produced by shifting the vertex 142t of the unit prism 142 to the left of the vertex 144t of the unit lens 144 when viewed from the observer O is used for the surface light source device. The result which calculated | required the output intensity distribution of this by simulation was shown.
Each evaluation lens sheet has substantially the same shape as the lens sheet 14 of the present embodiment, except that the magnitude of deviation (deviation amount Δx) of the apex 142t of the unit prism 142 is constant at a predetermined value.

  This simulation was performed on the assumption that light was incident from the direction of ± 75 ° (75 ° from the right side and 75 ° from the left side as viewed from the observer O) with respect to the sheet surface of the lens sheet for evaluation. The incident angle of ± 75 ° with respect to the sheet surface means that light in the peak direction of the emission angle of light emitted from the light source units 12A and 12B of the present embodiment and emitted from the light guide plate 13 in the arrangement direction of the unit prisms 142 is a lens. This corresponds to the incident angle incident on the sheet 14. The emission angle from the light guide plate 13 is substantially constant regardless of the position of the unit prisms 142 in the arrangement direction.

FIG. 3 shows the case where the position of the apex 142t of the unit prism 142 in the arrangement direction and the position of the apex 144t of the unit lens 144 match (when the amount of deviation Δx = 0 in the arrangement direction). The emission angle distribution is shown.
In FIG. 4A, the deviation Δx of the position of the vertex 142t of the unit prism 142 with respect to the position of the vertex 144t of the unit lenses 144 in the arrangement direction corresponds to 5% of the pitch P4 of the unit lenses 144 (Δx / P4 = FIG. 4B shows a deviation amount Δx of the position of the vertex 142t of the unit prism 142 with respect to the position of the vertex 144t of the unit lenses 144 in the arrangement direction. The light emission angle distribution in the case of (Δx / P4 = 0.10) corresponding to 10% of the pitch P4 is shown.

  In FIG. 5A, the amount of deviation Δx of the position of the vertex 142t of the unit prism 142 relative to the position of the vertex 144t of the unit lenses 144 in the arrangement direction corresponds to 15% of the pitch P4 of the unit lenses 144 (Δx / P4 = 0.15) shows a light emission angle distribution in the case of FIG. 5B, and FIG. 5B shows that the deviation Δx of the position of the vertex 142t of the unit prism 142 with respect to the position of the vertex 144t of the unit lenses 144 in the arrangement direction is the unit lens 144. The light emission angle distribution in the case of (Δx / P4 = 0.20) corresponding to 20% of the pitch P4 is shown.

As shown in FIG. 3, when the position of the apex 142t of the unit prism 142 and the position of the apex 144t of the unit lens 144 match in the arrangement direction, light having an incident angle of + 75 ° (corresponding to light from the light source unit 12A) ) Is emitted with a peak at about 2.5 degrees on the right side when viewed from the observer O, and light having an incident angle of −75 ° (corresponding to light from the light source unit 12B) is about 2. on the left side when viewed from the observer O. The light is emitted with a peak of 5 degrees.
However, as shown in FIGS. 4 and 5, the ratio of the deviation Δx to the arrangement pitch P4 of the unit lenses 144 from the position where the vertex 142t of the unit prism 142 coincides with the vertex 144t of the unit lens 144 is 5% and 10%, respectively. , 15% and 20%, respectively, by shifting to the left side when viewed from the observer O, light having an incident angle of + 75 ° (corresponding to light from the light source unit 12A) and light having an incident angle of −75 ° (from the light source unit 12B) In any case, the emission angle at the peak is shifted to the right side (center side) as viewed from the observer O.

As shown in FIG. 4A, when the shift amount is Δx / P4 = 0.05, light having an incident angle of + 75 ° is emitted with a peak at about 3.5 ° on the right side with respect to the front direction, and the incident angle is −75. The light at 0 ° was emitted with a peak at about 1.5 ° on the left side with respect to the front direction.
Further, as shown in FIG. 4B, when the deviation amount Δx / P4 = 10%, light having an incident angle of + 75 ° is emitted with a peak at about 5.5 ° on the right side with respect to the front direction. The 75 ° light was emitted with a peak at about 0 ° with respect to the front direction.
As shown in FIG. 5A, when the deviation amount Δx / P4 = 15%, light having an incident angle of + 75 ° is emitted with a peak at about 7.5 ° on the right side with respect to the front direction, and the incident angle is −75 °. Was emitted with a peak at about 1.5 ° on the right side with respect to the front direction.
Further, as shown in FIG. 5B, when the deviation amount Δx / P4 = 20%, the light having the incident angle of + 75 ° is emitted with the peak at about 9.5 ° on the right side with respect to the front direction, and the incident angle − The 75 ° light was emitted with a peak at about 2.5 ° on the right side with respect to the front direction.
As described above, as the ratio Δx / P4 of the deviation amount of the apex 142t of the unit prism 142 (that is, the deviation amount Δx) increases, light having an incident angle of ± 75 ° (corresponding to light from the light source units 12A and 12B). The emission angle at the peak of is changed to the right side (center side) as viewed from the observer O. Moreover, the angle between the two peak directions is substantially constant.

FIG. 6 is a diagram illustrating a state of light in each part of the left and right direction of the screen of the lens sheet of the first embodiment. 6A shows the state of light at the right end of the screen in the left-right direction, FIG. 6B shows the state of light at the center of the screen in the left-right direction, and FIG. The state of light at the left end is shown.
From the results shown in FIGS. 3 to 5, as shown in FIG. 6, in the region in which the vertex 142 t of the unit prism 142 is located outside the vertex 144 t of the corresponding unit lens 144 in the arrangement direction, the amount of deviation is large. Accordingly, it can be seen that the emission angle direction of the light with respect to the sheet surface is inclined inward as compared with the center in the arrangement direction.

For example, at the center in the horizontal direction of the screen, as shown in FIG. 6B, the light La and Lb from the light source units 12A and 12B are emitted in a direction that forms a predetermined angle with respect to the normal direction of the screen.
Further, at the right end in the left-right direction of the screen, as shown in FIG. 6A, the vertex 142t of the unit prism is located on the right side in the arrangement direction with respect to the vertex 144t of the unit lens, and the light La and Lb are emitted. The direction changes to the left side (center side) in the left-right direction of the screen as compared with the emission angle at the center in the left-right direction of the screen. Further, at the left end of the left and right direction of the screen, as shown in FIG. 6C, the vertex 142t of the unit prism is located on the left side in the arrangement direction with respect to the vertex 144t of the unit lens, and the light La and Lb are emitted. The angle changes to the right side (center side) of the screen in the left-right direction compared to the emission direction at the center in the left-right direction of the screen.
The magnitude of the change in the emission angle of the light La and Lb toward the center gradually increases from the center toward the both ends in the left-right direction of the screen in accordance with the vertex shift amount Δx.

Here, the display device 10 of the present embodiment using the lens sheet 14 of the present embodiment and the display device 30 of the comparative example using the lens sheet of the comparative example are compared.
FIG. 7 is a diagram illustrating light emission directions in the display device of the first embodiment and the display device of the comparative example. FIG. 7A shows the light emission direction in the display device 10 of the present embodiment, and FIG. 7B shows the light emission direction in the display device 30 of the comparative example. In FIGS. 7A and 7B, the display device is shown in a simplified manner for easy understanding.
The lens sheet (not shown) used in the display device 30 of the comparative example has a substantially isosceles triangular prism shape whose side surface of the unit prism is a plane, and the unit prism has an arrangement pitch equal to the arrangement pitch of the unit lenses, and its apex. Is coincident with the apex of the unit lens regardless of the position in the arrangement direction when viewed from the normal direction of the sheet surface. The lens sheet and the display device 30 of the comparative example have substantially the same shape as the lens sheet 14 and the display device 10 of the present embodiment, except that these points are different from the present embodiment.

In the display device 30 of the comparative example, as shown in FIG. 7B, the left-eye image light Lb reaches the left eye and the right-eye image light La reaches the right eye in the central portion in the horizontal direction of the screen. Thus, stereoscopic viewing is possible, and the observer O can observe a bright and good three-dimensional image.
However, in the display device 30 of the comparative example, the emission direction of the right-eye image light La and the left-eye image light b is the same as the emission direction at the center in the left-right direction of the screen at both ends in the left-right direction of the screen. . For this reason, in the display device 30 of the comparative example, the amount of light emitted from both ends of the screen in the left-right direction is greatly reduced, and the both ends of the screen in the left-right direction are dark when viewed from the observer O. Cross-talk occurs such that the right-eye image light emitted from both right and left ends of the screen reaches the left eye, resulting in incomplete stereoscopic view at both ends of the screen and 3D images observed. There is a problem that it cannot be performed, and the image quality of the 3D image is deteriorated.

On the other hand, in the display device 10 of the present embodiment including the lens sheet 14, the center portion in the arrangement direction has the light Lb for the left eye image and the light for the right eye image as shown in FIG. Each of La is emitted in a predetermined direction, the light Lb for the left-eye image reaches the left eye, and the light La for the right-eye image reaches the right eye. The observer O can view stereoscopically and is bright. A good 3D image can be observed.
Further, as shown in FIG. 7A, the emission angles of the respective video lights La and Lb are inclined toward the center side (inside) in the left-right direction of the screen at both ends in the left-right direction of the screen. In addition, the inclination increases as it goes toward both ends of the screen in the left-right direction.

This is because the vertex 142t of the unit prism 142 of the present embodiment is located on the outer side as it goes outward from the center in the screen arrangement direction as shown in FIGS. This is because the light emitted from the unit lenses 144 is emitted toward the inner side (center side in the arrangement direction) as the position in the arrangement direction becomes the outer side.
Thereby, in the display device 10 of the present embodiment, even if the light emitted from both ends of the screen in the left-right direction reaches the observer O side, a bright image is observed regardless of the position in the left-right direction of the screen. The Also, since the right-eye video reaches the right eye and the left-eye video reaches the left eye, crosstalk is greatly reduced, and a good three-dimensional video is observed regardless of the screen position. Therefore, according to the present embodiment, a good 3D image can be provided.

From the above, according to the present embodiment, it is possible to reduce as much as possible the non-uniformity of brightness that darkens the images at both ends in the left-right direction of the screen and the reduction in the visibility of 3D images at both ends in the left-right direction of the screen. Thus, it is possible to provide a lens sheet 14 capable of displaying a bright and good three-dimensional image, and a surface light source device and a transmissive display device including the lens sheet 14.
Further, by adjusting the amount of positional deviation Δx of the vertex 142t of the unit prism 142 with respect to the vertex 144t of the unit lens 144 in the arrangement direction, that is, the arrangement pitch P2 of the unit prism 142 and the arrangement pitch P4 of the unit lens 144. In addition, it is possible to easily cope with the screen size and the observation distance.

(Second Embodiment)
FIG. 8 is a diagram illustrating the shape of the lens sheet of the second embodiment. FIG. 8A shows a cross section orthogonal to the sheet surface of the lens sheet 24 of the second embodiment and parallel to the arrangement direction of the unit prisms 142 and unit lenses 144 (the horizontal direction of the screen). FIG. 8B is an enlarged view of one end portion in the arrangement direction (the right end portion in the left-right direction of the screen as viewed from the observer O) in the cross section of FIG. 8A, and FIG. 8A is an enlarged view of the center in the arrangement direction (the center in the horizontal direction of the screen) in the cross section of FIG. 8A, and FIG. 8D is the other end portion in the arrangement direction (observation) in the cross section of FIG. It is an enlarged view of a screen left-right direction left end portion as viewed from the person O.
The lens sheet 24 of the second embodiment is substantially the same as the lens sheet 14 described above, except that the shape of the unit prism 242 is different from the unit prism 142 shown in the first embodiment. Therefore, parts having the same functions as those in the first embodiment described above are denoted by the same reference numerals or the same reference numerals at the end, and repeated description is appropriately omitted.
The lens sheet 24 according to the second embodiment includes a lens layer 145 in which unit lenses 144 are arranged, a base material layer 141, and a prism layer 243 in which unit prisms 242 are arranged. The lens sheet 24 can be used for the surface light source device and the display device 10 in the same manner as the lens sheet 14 of the first embodiment.

  The prism layer 243 is formed on the incident-side surface of the base material layer 141, and a plurality of unit prisms 242 are arranged on the incident-side surface. The unit prism 242 has a substantially isosceles triangular prism shape, but its side surfaces 242a and 242b are concave curved surfaces that are concave when viewed from the incident side (light guide plate 13 side), and are side surfaces in that they are valley bottoms of the unit prism 142. 242a and 242b are connected smoothly. The curved surface formed by the side surface 242a of the unit prism 242 and the side surface 242b of the unit prism 242 adjacent thereto is substantially parabolic in the cross section shown in FIG. Note that in the cross section that is parallel to the arrangement direction of the unit prisms 242 and orthogonal to the sheet surface, the curves formed by the side surfaces 242a and 242b of the adjacent unit prisms 242 may be substantially catenary curves.

The unit prisms 242 are arranged in a direction parallel to the arrangement direction of the unit lenses 144. The unit prism 242 has a constant shape regardless of the position in the arrangement direction. The arrangement pitch P2 of the unit prisms 242 is constant regardless of the position in the arrangement direction, and is larger than the arrangement pitch P4 of the unit lenses 144. In the present embodiment, an example in which the shape of the unit prism 242 is constant is shown, but the present invention is not limited to this, and the shape of the unit prism 242 may be changed.
The vertex 242t of the unit prism 242 coincides with the vertex 144t of the unit lens 144 when viewed from the normal direction of the sheet surface at the center in the arrangement direction. However, as it approaches the end side along the arrangement direction, the vertex 242t of the unit prism 242 is gradually positioned on the end side (outside) with respect to the vertex 144t, and the shift amount Δx also increases.

  The vertex 242t of the unit prism 242 may be located closer to the base material layer 141 than the focal position of the unit lens when parallel light is irradiated from the unit lens 144 side at the center of the screen arrangement direction. May match. Even when the apex 242t is located closer to the base material layer than the focal position, the light from the light guide plate can be efficiently launched to the emission side with the unit prism 242 of the present embodiment.

  As an example of the lens sheet 24 of the present embodiment, for example, a lens sheet 24 having the following dimensions can be used. In the lens sheet 24 of the embodiment, the arrangement pitch P4 of the unit lenses 144 is about 70 μm, the radius of curvature is about 50 μm, and the land thickness is about 10 μm. Further, the thickness of the base material layer 141 is T = 38 μm. Furthermore, the unit prism 242 has a prism height (a dimension in the thickness direction from the valley bottom between the unit prisms 242 to the apex 242t) of about 30 μm, a land thickness of about 15 μm, and the arrangement of the unit prisms 242. Macroscopically, the pitch P2 is substantially the same as the arrangement pitch P4 of the unit lenses 144, but in practice, the pitch P2 is slightly larger than the arrangement pitch P4 of the unit lenses 144 to the extent that it is difficult to measure the difference. The ratio Δx / P of the shift amount Δx between the apex 144t and the apex 242t in the arrangement direction of the unit lenses 144 and the unit prisms 242 to the arrangement pitch P4 of the unit lenses 144 is Δx at the center of the arrangement direction (left-right direction of the screen). / P4 = 0 (ie, Δx = 0), and Δx / P4 = 0.15 at both ends.

Even in such a configuration, as in the first embodiment described above, it is possible to reduce luminance reduction at both ends in the left-right direction of the screen, reduction in visibility of 3D video, and the like as much as possible. Better 3D images can be displayed to the user.
Further, in the lens sheet 24 of the present embodiment, the side surface of the unit prism 242 has a concave curved surface, so that the light beam incident near the apex 242t to the unit prism 242 is concave on the side surface during incidence and total reflection. The emission direction can be widened by the curved surface shape. Therefore, by using the lens sheet 24 of the present embodiment for the display device 10, it is possible to expect an effect of improving image feeling and moire that are likely to occur when a unit prism having a flat side surface is used. Furthermore, even when the accuracy of the shape and dimensions near the apex of the unit prism is not so high, light can be launched to the observer O side.

(Deformation)
Without being limited to the embodiments described above, various modifications and changes are possible, and these are also within the scope of the present invention.
(1) In each embodiment, the unit lens 144 is an example of a substantially cylindrical cylindrical lens. However, the unit lens 144 is not limited to this example. For example, the unit lens 144 may be a part of an elliptical column shape whose long axis is orthogonal to the sheet surface. Also good.

(2) In each embodiment, as shown in FIG. 2 and FIG. 8 and the like, the unit prisms 142 and 242 are examples in which the tip portions including the apexes 142t and 242t are pointed, but the present invention is not limited thereto. For example, it is good also as a form in which the front-end | tip part is formed with the curved surface which becomes convex to the light-guide plate 13 side (incident side). By adopting such a configuration, the tip portions of the unit prisms 142 and 242 are not easily damaged.

(3) In each embodiment, the unit lens 144 has an example in which the pitch is constant in the arrangement direction. However, the present invention is not limited to this. For example, the unit lens 144 has a constant arrangement pitch P2, and the unit lenses 144 are arranged. The pitch P4 may be adjusted in the arrangement direction, for example.

(4) In each embodiment, the unit lens 144 of the lens sheets 14 and 24 is formed of an ultraviolet curable resin on the emission side of the base material layer 141. However, the present invention is not limited thereto. 145 (unit lens 144) and base material layer 141 may be made of a thermoplastic resin, and may be integrally molded by extrusion molding or the like. By setting it as such a form, since the base material layer 141 and a unit lens are formed at once, manufacture is easy.

(5) In each embodiment, although the base material layer 141 showed the example made from PET resin, it is not restricted to this, For example, PC resin, TAC (triacetyl cellulose), PEN (polyethylene naphthalate) resin A sheet-like member can be used.

(6) In each embodiment, the light guide plate 13 has an example in which dots (not shown) having a diffusing action are formed on the back side surface by printing or the like. Various unit lenses or the like may be arranged on the back side surface or the emission side (LCD panel 11 side) surface, or the back surface may not have dots or the like. In addition, the light guide plate 13 may include a diffusing material or the like.

(7) In each embodiment, the display device 10 has shown an example in which the screen size of the LCD panel 11 is 2.8 inches diagonal. However, the display device 10 is not limited to this, and a larger screen size, for example, 4 inches diagonal. Or 7 inches or smaller sizes. In the case of such a large screen size, a decrease in the visibility of the three-dimensional image and a decrease in the luminance of the image due to crosstalk at both ends in the left-right direction of the screen tend to be problematic, but the lens sheets 14 and 24 of the respective embodiments. By adopting, those problems can be improved and better 3D images can be displayed.

(8) In each embodiment, although the light source part 12A, 12B used the light source as the LED light source and used in combination with the light guide, the present invention is not limited to this. For example, a cold cathode tube is used as the light source part. Also good. At this time, a shutter capable of shielding light from the cold cathode tube may be provided between the cold cathode tube and the light guide plate 13, and the opening / closing of the shutter and the display of the image on the LCD panel 11 may be synchronized. Further, a plurality of point light sources such as LEDs may be arranged along the light incident surfaces 13a and 13b.

  In addition, although this embodiment and modification can also be used in combination as appropriate, detailed description is abbreviate | omitted. Further, the present invention is not limited by the embodiments described above.

DESCRIPTION OF SYMBOLS 10 Display apparatus 11 LCD panel 12A, 12B Light source part 13 Light guide plate 14, 24 Lens sheet 141 Base material layer 142,242 Unit prism 143,243 Prism layer 144 Unit lens 145 Lens layer 15 Control part

Claims (9)

Used for a surface light source device that irradiates a transmissive display unit of a transmissive display device capable of displaying a stereoscopic image by alternately emitting right-eye video light and left-eye video light in predetermined directions. A lens sheet with optical shapes formed on both sides,
A sheet-like base material layer;
A lens layer formed by arranging a plurality of convex unit lenses having a substantially cylindrical partial shape or a substantially elliptical columnar partial shape on the emission side of the base material layer;
A prism layer formed by arranging a plurality of convex unit prisms on the incident side of the base material layer;
With
The unit prisms are substantially triangular prisms, and a plurality of unit prisms are arranged in a direction parallel to the arrangement direction of the unit lenses, and one unit prism corresponds to one unit lens through the base material layer. And
In the center of the arrangement direction of the unit lenses, the unit prism and the unit lens corresponding to the unit lenses have the same vertex position when viewed from the normal direction of the sheet surface,
As the unit lens is arranged from the center in the arrangement direction toward the end, the apex of the unit prism is gradually positioned closer to the end with respect to the apex of the unit lens, and viewed from the normal direction of the sheet surface, The amount of deviation in the arrangement direction of the unit lens between the vertex of the unit lens and the vertex of the unit prism corresponding to the unit lens gradually increases.
Lens sheet characterized by The lens sheet according to claim 1,
The arrangement pitch of the unit prisms is larger than the arrangement pitch of the unit lenses;
Lens sheet characterized by The lens sheet according to claim 1,
The arrangement pitch of the unit prisms is constant,
The arrangement pitch of the unit lenses gradually decreases in the arrangement direction from the center toward both ends.
Lens sheet characterized by In the lens sheet according to any one of claims 1 to 3,
The vertex of the unit prism is located within the lens width of the unit lens corresponding to the unit prism in the arrangement direction thereof;
Lens sheet characterized by In the lens sheet according to any one of claims 1 to 4,
A side surface of the unit prism is a concave curved surface;
Lens sheet characterized by The lens sheet according to claim 5,
The vertex of the unit prism is at the base layer side in the thickness direction of the lens sheet than the focal position of the parallel light when the parallel light is irradiated from the unit lens side at the center in the arrangement direction of the unit lenses. Located in the
Lens sheet characterized by In the lens sheet according to any one of claims 1 to 6,
The unit prism is made of ionizing radiation curable resin;
Lens sheet characterized by The lens sheet according to any one of claims 1 to 7,
A light guide plate disposed on the prism layer side with respect to the lens sheet;
A first light source part and a second light source part respectively disposed at positions facing both end faces of the light guide plate in the arrangement direction of the unit prisms;
A surface light source device. A surface light source device according to claim 8,
A transmissive display unit illuminated from the back side by the surface light source device;
With
The first light source unit and the second light source unit are alternately turned on and off repeatedly,
The transmissive display unit is
When the first light source unit is turned on and the second light source unit is turned off, a right eye image is displayed,
When the second light source unit is turned on and the first light source unit is turned off, an image for the left eye is displayed,
Switching the video to be displayed in synchronization with turning on and off of the first light source unit and the second light source unit;
A transmissive display device characterized by the above.

Images