JP2012128252A - Deflection optical sheet, surface light source device, video source module, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface light source device for liquid crystal display devices capable of reducing the weight.SOLUTION: A deflection optical sheet 12 deflecting light from a light source 11 to emit it in a different direction from the incident light, includes: a sheet-like base material section 13; and a prism section 14 disposed with a plurality of unit prisms 14a that have light incidence planes 14b and total reflection planes 14c for totally reflecting light entering from the light incidence plane, and that are projectingly formed from the base material section. The unit prisms have a prescribed cross section, extend in one direction, are juxtaposed in the direction orthogonal to the extending direction and, when a pitch in the juxtaposed direction of the unit prism is defined as P (mm) and the juxtaposed-directional width of the unit prism is defined as W (mm), an expression P>W is satisfied.

Description

  The present invention relates to a deflecting optical sheet that deflects light, a surface light source device using the same, a video source module, and a liquid crystal display device.

  A liquid crystal display device such as a liquid crystal television is provided with a surface light source device that illuminates the liquid crystal display panel from the back side. The surface light source device is roughly classified into a direct type in which a light source is arranged facing the sheet surface of a sheet-like optical member and an edge light type in which a light source is arranged on the side of the optical member. The edge light type surface light source device has an advantage that the thickness of the surface light source device can be reduced as compared with the direct type surface light source device.

  The edge light type surface light source device is provided with a light guide plate that faces the liquid crystal display panel and guides light from the side. Light from the light source enters the light guide plate from the side surface (light incident surface) of the light guide plate. The light that has entered the light guide plate travels through the light guide plate in the direction of the light guide (in the light guide direction) while repeating reflection in the light guide plate. The light traveling in the light guide plate is gradually emitted from the light exit surface as it travels in the light guide direction. As a result, the amount of light emitted from the light exit surface of the light guide plate is made uniform along the light guide direction.

  Patent Document 1 discloses a method of manufacturing a light guide plate, in which, for example, an edge light type surface light source device using a light guide plate is shown as shown in FIG. Such an edge light type surface light source device includes a light source (5) and a light guide plate (2), and has a reflective sheet (3) on the back surface of the light guide plate (2). Furthermore, between the light guide plate (2) and the liquid crystal display panel (11), there are provided a light diffusion sheet (7) and two prism sheets (23, 24) having different extending directions (orthogonal).

JP 2007-227405 A

However, in the conventional edge light type surface light source device as described in Patent Document 1, there are many components, and in particular, the light guide plate is often a printed light guide plate. there were. In addition, the cost tends to increase from the viewpoint that there are many components.
In addition to this, as the optical performance of the surface light source device, there is a demand for efficiently converging light from the light source and emitting light with high energy efficiency to increase luminance.

  In view of the above problems, it is an object of the present invention to provide a deflection optical sheet that can be reduced in weight and can improve light convergence. In addition, a surface light source device, an image source module, and a liquid crystal display device including the deflection optical sheet are 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 a deflecting optical sheet (12) that deflects light from the light source (11) and emits it in a direction different from the incident light, and comprises a sheet-like base material portion (13) and A prism portion having a light incident surface (14b) and a total reflection surface (14c) that totally reflects light incident from the light incident surface, and a plurality of unit prisms (14a) formed to protrude from the base material portion (14), and the unit prism has a predetermined cross section and extends in one direction, and is arranged in parallel in a direction orthogonal to the extending direction, and the pitch in the parallel direction of the unit prism is P (mm), When the parallel direction width of the unit prism is W (mm),
P> W
Is a deflecting optical sheet.

According to a second aspect of the present invention, in the deflecting optical sheet (12) according to the first aspect, the parallel direction width of the unit prism (14a) is W (mm), and the thickness of the base portion (13) is D ( mm)
D ≧ W
Is established.

According to a third aspect of the present invention, in the deflecting optical sheet (12) according to the first or second aspect, the parallel pitch of the unit prisms (14a) is P (mm), and the parallel width of the unit prisms is W ( mm)
P ≧ 2 ・ W
Is established.

The invention according to claim 4 is a surface light source device (10, 110) for emitting light to the liquid crystal cell from the back side of the liquid crystal cell (21), and the light source (11) and the light from the light source are incident And a deflecting optical sheet (12) that deflects and emits light. The deflecting optical sheet includes a sheet-like base material portion and a plurality of unit prisms (14a) on the side of the base material portion on which the light source is disposed. ) Are arranged, and the unit prism includes a light incident surface (14b) for allowing light from the light source to enter the unit prism, and a total reflection for totally reflecting the light incident from the light incident surface. The unit prism has a predetermined cross section, extends in one direction, and is arranged in a direction orthogonal to the extending direction, and the pitch in the parallel direction of the unit prism is P (mm). When the parallel direction width of the unit prism is W (mm),
P> W
Is a surface light source device (10).

According to a fifth aspect of the present invention, in the surface light source device (10, 110) according to the fourth aspect, the parallel direction width of the unit prism (14a) is W (mm), and the thickness of the base portion (13) is the same. When D (mm)
D ≧ W
Is established.

According to a sixth aspect of the present invention, in the surface light source device (10, 110) according to the fourth or fifth aspect, the pitch in the parallel direction of the unit prisms (14a) is P (mm) and the width in the parallel direction of the unit prisms. When W (mm)
P ≧ 2 ・ W
Is established.

  According to a seventh aspect of the present invention, in the surface light source device (10, 110) according to any one of the fourth to sixth aspects, the prism portion (14) of the deflecting optical sheet (12) is formed. On the side, a reflection sheet (15) that reflects light is disposed facing the deflecting optical sheet (12).

  According to an eighth aspect of the present invention, in the surface light source device (10, 110) according to any one of the fourth to seventh aspects, the prism portion (14) of the deflecting optical sheet (12) is formed. A reflective polarizing film (16) that transmits only light of a predetermined property and reflects other light is laminated on the surface opposite to the side.

  The invention according to claim 9 is the surface light source device (10, 110) according to claims 4 to 8, and the liquid crystal cell (21) disposed on the opposite side of the surface light source device from the light source (11). Is a video source module (1, 101).

  The invention according to claim 10 is the surface light source device (110) according to claim 8, the liquid crystal cell (21) laminated on the reflective polarizing film (16) of the surface light source device, and the liquid crystal cell. An image source module (101) comprising a laminated upper polarizing plate (22).

  The invention described in claim 11 is a liquid crystal display device comprising the video source module (1, 101) according to claim 9 or 10.

  According to the present invention, it is possible to provide a deflecting optical sheet that can be reduced in weight and can improve light convergence and light utilization efficiency. Further, the surface light source device, the image source module, and the liquid crystal display device using the deflection optical sheet are also reduced in weight, and the light convergence and the light use efficiency can be improved.

It is a figure explaining 1st embodiment and is an exploded perspective view of an image source module. FIG. 2 is an exploded cross-sectional view showing a cross section taken along the line II-II in FIG. 1. FIG. 3 is a front view of the deflecting optical sheet and the light source viewed from the direction indicated by an arrow III in FIG. 1. It is a figure explaining the structure of a deflection | deviation optical sheet. It is a schematic diagram showing a part of manufacturing process of a deflection | deviation optical sheet. It is a figure explaining the example of an optical path. It is a figure explaining 2nd embodiment and is a figure equivalent to FIG. It is a figure explaining 3rd embodiment and is a figure equivalent to FIG.

  The above-described operation and gain of the present invention will be clarified from embodiments for carrying out the invention described below. Hereinafter, the present invention will be described based on embodiments shown in the drawings. However, the present invention is not limited to these embodiments.

  1-3 is a figure for demonstrating 1st embodiment. FIG. 1 is an exploded perspective view schematically showing a configuration of an image source module 1 included in a display device including a deflecting optical sheet 12. 2 is an exploded cross-sectional view taken along the line II-II in FIG. FIG. 3 is a front view of the deflection optical sheet 12 and the light source 11 as seen from the direction indicated by the arrow III in FIG. 1 and 2, the left side of the drawing is the light source side, and the right side of the drawing is the viewer side. FIG. 3 shows the deflection optical sheet 12 as viewed from the light source 11 side. In addition, the figures shown below including FIGS. 1-3 may change and exaggerate each part shape for easy understanding, and the code | symbol which becomes repeated may be abbreviate | omitted. Description will be made with reference to FIGS.

  The display device of the present embodiment is a liquid crystal display device and includes a video source module 1. In addition, although illustration and description are omitted, the display device includes various known devices for functioning as a liquid crystal display device.

  The video source module 1 includes a surface light source device 10 and a liquid crystal display panel 20 provided on the viewer side of the surface light source device 10. The surface light source device 10 is a device that illuminates the liquid crystal display panel 20 from the back side (the side opposite to the observer). On the other hand, the liquid crystal display panel 20 is a panel that includes video information and appropriately provides the viewer with video information by transmitting or blocking light from the surface light source device 10. Each will be described below.

The surface light source device 10 includes a light source 11, a deflecting optical sheet 12, a reflective sheet 15, a reflective polarizing film (DBEF) 16, and a light diffusion sheet 17.
The light source 11 is a device that projects light to the deflection optical sheet 12 from obliquely below. In the light source 11, a plurality of light sources 11 a are arranged below the deflection optical sheet 12 in the horizontal direction. The light source 11a includes an LED (light emitting diode) or an incandescent bulb as a light source, and an optical system for enlarging and projecting light emitted from the light source in a predetermined manner. Specifically, each light source 11a emits light so as to cover substantially the entire vertical direction of the prism portion 14 so that the light is inclined in a direction in which unit prism portions 14a described later are arranged in parallel, as indicated by a dotted line in FIG. Is emitted.

  The deflecting optical sheet 12 has a function of deflecting light projected obliquely from the light source 11 disposed on the back side and condensing the light so as to approach the normal line direction of the liquid crystal display panel 20. Therefore, the deflection optical sheet 12 includes a base portion 13 and a prism portion 14, and the prism portion 14 is provided with a plurality of unit prisms 14 a.

  The base material portion 13 is a sheet-like portion having translucency that serves as a base material for forming the prism portion 14 and supports the prism portion 14 so as to prevent deformation. From this point of view, specific examples of the material constituting the base material portion 13 include an acrylic resin, a styrene resin, a polyester resin, a polycarbonate resin, and an acrylic-styrene copolymer resin.

The prism portion 14 is a part having a plurality of unit prisms 14a. Each unit prism 14a has a portion having a substantially triangular cross section. The surfaces forming the hypotenuse are a light incident surface 14b for allowing the light from the light source 11 to enter the unit prism 14a and a total reflection surface 14c for totally reflecting the incident light. The light incident surface 14b is the surface facing the light source 11, and the total reflection surface 14c is the opposite surface. 1 to 3, the unit prism 14a has a cross section shown in FIG. 2 and has a linear shape extending in the horizontal direction, and the plurality of unit prisms 14a are arranged in a direction orthogonal to the extending direction. Are in parallel.
Further, the plurality of unit prisms 14a are arranged in parallel at a predetermined interval, and a gap surface 14d is formed at the interval. In the present embodiment, the surface of the base material portion 13 appears between the unit prisms 14a and becomes a smooth surface, which functions as the gap surface 14d.
According to such a deflection optical sheet 12, reflected light passes through the gap surface 14d as will be described later, so that the light can be used effectively and the luminance can be improved. .

The deflection optical sheet 12 will be described in more detail. FIG. 4 shows an explanatory diagram. FIG. 4 is an enlarged view of a part of the deflection optical sheet 12. As described above, since light is projected from the light source 11 disposed on the back side to the deflection optical sheet 12 from an oblique direction, the light enters the unit prisms 14a at different angles. The deflecting optical sheet 12 has a function of deflecting the incident light and bringing it closer (condensed) in the normal direction of the liquid crystal display panel 20. Accordingly, each unit prism 14a can have a shape for realizing such a function.
As shown in FIG. 4, the angle between the light incident on a certain unit prism 14a (shown by a dotted line in FIG. 4) and the normal direction of the liquid crystal display panel 20 is θ ₁ , and the light emitted from the unit prism 14a is When the angle formed with the normal direction of the liquid crystal display panel 20 is θ ₂ , the apex angle formed by the light incident surface 14b and the total reflection surface 14c of the unit prism 14a is λ, and the refractive index of the unit prism 14a is n. The angle φ formed by the total reflection surface 14c of the unit prism 14a and the panel surface of the liquid crystal display panel 20 (shown by a broken line in FIG. 4) can be obtained by the following equation (1).

Here, the light exiting from the unit prisms 14a when it is desired to the normal direction of the liquid crystal display panel 20, the theta ₂ may be set to 0 °.
As described above, the shape of the unit prism 14a can be determined by the position of the light source 11, the material of the unit prism 14a, and the like. According to this, the apex angle λ and the angle φ of each unit prism 14 a vary depending on the position where the unit prism 14 a is disposed, and the apex angle λ on the far side is larger than the side closer to the light source 11. A continuously changing shape can be obtained. However, the present invention is not limited to this, and the apex angles λ and φ may be constant in all or some of the unit prisms.

Here, θ ₁ may be appropriately irradiated with light from the light source 11 over the entire surface of the prism portion 14, and is not particularly limited, but it is preferable to make θ ₁ as large as possible from the viewpoint of thickness reduction. . From this viewpoint, θ ₁ is preferably 60 ° or more and 85 ° or less.

Further, from the viewpoint of more efficiently exhibiting the optical action described later, the unit prism 14a is preferably in the following manner. That is, when the pitch between the unit prisms 14a is P (mm), the width in the parallel direction of the unit prisms 14a is W (mm), and the protruding height of the unit prisms 14a is H (mm), the incident angle θ of the light source light _In relation to ₁ , it is preferable that Formula (2) is established.
(P + 0.5 · W) · tan (90 ° −θ ₁ ) ≦ H (2)
According to this, the light from the light source 11 is irradiated to the whole total reflection surface 14c of the unit prism 14a, and the whole total reflection surface 14c can be used effectively.

Equation (2) can be derived as follows. This will be described with reference to FIG. That is, the minimum condition for the light having the angle θ ₁ to reach the total reflection surface 14c of the unit prism 14a passes through the vertex A of the unit prism 14a immediately before the unit prism 14a to be reached, and the unit prism to be reached. It is necessary to reach the point B closest to the base material part 13 of the total reflection surface 14c of 14a. Since the side AC is H if the angle formed by the side AB with the pitch direction of the unit prism 14a is α and the point where the perpendicular from the vertex A to the base material part 13 intersects the base material part 13 is C, the side AC is H.
tan α = H / (P + 0.5 · W)
Is established. Here, when α as the minimum condition is expressed by the incident angle θ ₁ of the light source light, α = 90 ° −θ ₁ .
tan (90 ° −θ ₁ ) = H / (P + 0.5 · W)
It becomes. Since the equal sign is a minimum requirement,
tan (90 ° −θ ₁ ) ≦ H / (P + 0.5 · W)
If it is. By organizing this, equation (2) can be obtained.

  That is, the shape of the unit prism 14a may be determined so as to satisfy Expression (2), or the position of the light source 11 may be determined so as to satisfy Expression (2).

As described above, since a gap is provided between the unit prisms 14a and a gap surface 14d is formed, Expression (3) is established.
P> W (3)
Further, from the viewpoint of securing the quantity of the unit prism portions 14a and sufficiently providing the size of the gap surface 14d to improve the light utilization rate more effectively, it is preferable that the equation (4) is satisfied.
P ≧ 2 ・ W (4)

In consideration of the formula (2), the formula (5) is preferable, and the formula (6) is more preferable.
W <P ≦ (H / tan (90 ° −θ ₁ )) − 0.5 · W (5)
2 · W ≦ P ≦ (H / tan (90 ° −θ ₁ )) − 0.5 · W (6)

Further, as will be described later, from the viewpoint of efficiently passing the reflected light from the reflective polarizing film 16 through the gap surface 14d, when the thickness of the base material portion 13 is D (mm), Expression (7) is established. It is preferable.
D ≧ W (7)
That is, when the thickness D of the base portion 13 is the same as or greater than that of W, the reflected light from the reflective polarizing film 16 (see L2 and L3 in FIG. 6) is unit prism as described later. The amount of light that again enters 14a can be reduced, and the amount of light that passes through the gap surface 14d can be increased.

  The material which comprises the prism part 14 will not be specifically limited if it can have the above functions, A various material can be used. For example, acrylic, styrene, polycarbonate, polyethylene, which are widely used as materials for optical sheets incorporated in display devices and have excellent mechanical properties, optical properties, stability, processability, etc., and are available at low cost A transparent resin mainly composed of one or more of terephthalate, acrylonitrile and the like, an epoxy acrylate, a urethane acrylate-based reactive resin (such as an ionizing radiation curable resin), and the like can be used.

  Such a deflection optical sheet 12 can be manufactured by extrusion molding, or by shaping or sticking the prism portion 14 on the base material portion 13. In the deflecting optical sheet 12 manufactured by extrusion molding, the base material portion 13 and the prism portion 14 can be integrally formed. Moreover, when manufacturing the deflection | deviation optical sheet 12 by shaping or sticking, the material which makes the prism part 14 may differ from the material which the base material part 13 makes, and may be the same. FIG. 5 schematically illustrates a part of the process for an example of the method for manufacturing the deflecting optical sheet 12.

  When the deflection optical sheet 12 is manufactured, as shown in FIG. 5, the prism portion 14 is formed on the base material 13 ′ including the layer that becomes the base material portion 13. Specifically, it is as follows. In order to form the prism portion 14, a mold roll 300 having a groove having a shape corresponding to the shape of the prism portion 14 at a predetermined pitch is prepared. Next, the base material 13 ′ is fed between the mold roll 300 and the nip roll 301. The arrow V shown in FIG. 5 is the direction in which the substrate 13 'is fed. In accordance with the feeding of the base material 13 ′, the droplets of the composition 304 constituting the prism portion are continuously supplied from the supply device 303 between the mold roll 300 and the base material 13 ′. When the composition 304 is supplied from the supply device 303 onto the base material 13 ′, a bank 305 in which the composition 304 is accumulated is formed between the mold roll 300 and the base material 13 ′. In this bank 305, the composition 304 spreads in the width direction of the base material 13 '.

  The composition 304 supplied between the mold roll 300 and the base material 13 ′ as described above is caused by the pressing force between the mold roll 300 and the nip roll 301 between the base material 13 ′ and the mold roll 300. Filled in between. Thereafter, the light irradiation device 306 can irradiate the composition 304 with light to cure the composition 304 and form the prism portion 14. After the prism portion 14 is formed, the sheet is pulled from the mold roll 300 by being pulled using the peeling roll 307.

  Returning to FIGS. 1 to 3, another configuration will be described. The reflection sheet 15 is a sheet-like member disposed with a predetermined gap facing the surface of the deflecting optical sheet 12 on the side where the prism portion 14 is formed. The reflection sheet 15 should just have the function to reflect the light which reached here. For this, for example, a sheet made of a material having a high reflectivity such as a metal, a sheet including a thin film made of a material having a high reflectivity (for example, a metal thin film) as a surface layer, or the like that enables so-called specular reflection is preferable Can be applied.

The reflective polarizing film 16 is sometimes referred to as DBEF, and transmits light of a predetermined property (P wave in the present embodiment) using light interference, and light of other properties (S wave in the present embodiment). ) Is reflected. That is, since the lower polarizing plate 23 of the liquid crystal display panel 20 to be described later transmits only the P wave and absorbs the S wave in this embodiment, before the S wave is absorbed by the lower polarizing plate 23. The light utilization efficiency can be improved by reflecting the light with the reflective polarizing film 16 and returning to the light source 11 side for reuse. A part of the S wave reflected by the reflective polarizing film 16 is converted into a P wave by repeating reflection and scattering, and when it reaches the reflective polarizing film 16 again, it is transmitted through the reflective polarizing film 16. To the liquid crystal display panel 20. Details will be described later.
As the reflective polarizing film 16, a known one can be applied. Here, the reflective polarizing film 16 is preferably adhered to the surface of the deflecting optical sheet 12 opposite to the side on which the prism portion 14 is formed with an adhesive or the like.

  The light diffusing sheet 17 is a sheet-like member that diffuses the light transmitted through the reflective polarizing film 16 and is strongly converged due to the action of the deflecting optical sheet 12 so that the angle of the light becomes strong. Has the function of widening the luminance distribution. Thereby, a viewing angle can be expanded to some extent. Specifically, the light diffusing sheet 17 is configured by dispersing a light scattering agent (light diffusing particles) in a main part having translucency. The light scattering agent acts on the light traveling in the main part by changing the path direction of the light by reflection or refraction. In order to exhibit the light diffusion function (light scattering function) of such a light scattering agent, for example, the light scattering agent can be composed of a material having a refractive index different from that of the material constituting the main part. In addition, the material which can have a reflective effect with respect to light may be sufficient.

  The material constituting the main part is not particularly limited, and various materials can be used. However, it is widely used as a material for a normal optical sheet incorporated in a display device, and has excellent mechanical properties, optical properties, stability, workability and the like, and can be obtained at a low price, such as acrylic, styrene, A transparent resin mainly composed of one or more of polycarbonate, polyethylene terephthalate, acrylonitrile, etc., and an epoxy acrylate or urethane acrylate-based reactive resin (such as ionizing radiation curable resin) can be suitably used. On the other hand, the light scattering agent is, for example, silica (silicon dioxide), alumina (aluminum oxide), acrylic resin, polycarbonate resin, silicone resin, barium sulfate, titanium oxide or the like having an average particle size of about 0.5 μm to 100 μm. Can be used.

  The light diffusion sheet 17 is preferably adhered to the surface of the reflective polarizing film 16 with an adhesive or the like. Further, the surface of the light diffusion sheet 17 on the liquid crystal display panel 20 side is preferably a flat surface. Accordingly, the liquid crystal display panel 20 or other layers that may be disposed between the liquid crystal display panel 20 and the other layers can be appropriately adhered and stacked. Here, the “flat surface” represents a flatness that allows the surface light source device 10 to be stably laminated and bonded to another layer having a similar flat surface. This can be, for example, 1.0 μm or less when measured as a ten-point average roughness Rz in accordance with JIS B 0601 (1982).

  Next, the liquid crystal display panel 20 will be described. The liquid crystal display panel 20 includes an upper polarizing plate 22 disposed on the viewer side, a lower polarizing plate 23 disposed on the surface light source device 10 side, and between the upper polarizing plate 22 and the lower polarizing plate 23. The liquid crystal cell 21 is disposed. The upper and lower polarizing plates 22 and 23 decompose incident light into two orthogonal polarization components (P wave and S wave), and a polarization component (for example, P wave) in one direction (direction parallel to the transmission axis). And the polarization component (for example, S wave) in the other direction (direction parallel to the absorption axis) perpendicular to the one direction is absorbed.

  An electric field can be applied to the liquid crystal cell 21 for each region where one pixel is formed. Then, the orientation of the liquid crystal cell 21 to which an electric field is applied changes. When a polarized component (in this embodiment, P wave) transmitted through the lower polarizing plate 23 disposed on the surface light source device 10 side (that is, the light incident side) passes through the liquid crystal cell 21 to which an electric field is applied. The polarization direction is rotated by 90 °, while the polarization direction is maintained when passing through the liquid crystal cell 21 to which no electric field is applied. Therefore, depending on whether or not an electric field is applied to the liquid crystal cell 21, the polarization component (P wave) in a specific direction that has passed through the lower polarizing plate 23 further passes through the upper polarizing plate 22 disposed on the light output side of the lower polarizing plate 23. It is possible to control whether the light is absorbed or blocked by the upper polarizing plate 22.

  In this way, the liquid crystal display panel 20 is configured so that an image can be expressed by controlling transmission or blocking of light from the surface light source device 10 for each pixel. In the present embodiment, a commonly used liquid crystal display panel can be used.

  Next, the operation of the video source module 1 and the display device focusing on the surface light source device 10 will be described with reference to FIG. FIG. 6 shows optical path examples L0 to L3.

  Light is emitted from the light source 11 so as to be inclined in the parallel direction of the unit prisms 14a so as to include the unit prisms 14a disposed at the top to the unit prisms 14a disposed at the bottom. Is done. An example of one optical path included therein will be described with reference to FIG. The light L0 emitted from the light source 11 enters the unit prism 14a from the light incident surface 14b of the unit prism 14a, is totally reflected by the total reflection surface 14c, and the direction thereof can be brought close to the normal direction of the liquid crystal display panel 20. And are emitted from the deflecting optical sheet 12. Of the light transmitted through the deflecting optical sheet 12, light having a predetermined property indicated by L1 (P wave in the present embodiment) is transmitted through the reflective polarizing film 16 and the light diffusion sheet 17, and the liquid crystal display panel 20 To reach. At this time, in the light diffusion sheet 17, the viewing angle is widened by the above-described light diffusion action, and light is provided to the liquid crystal display panel 20.

  On the other hand, light having other properties that cannot be transmitted through the reflective polarizing film 16 (S wave in this embodiment) is reflected by the reflective polarizing film 16 as shown by L2 in FIG. It passes through the gap surface 14 d of the optical sheet 12 and reaches the reflection sheet 15. The light reflected by the reflecting sheet 15 passes through the gap optical surface 12d of the deflecting optical sheet 12 again and passes through the deflecting optical sheet 12. At this time, at least a part of L2 changes its property due to reflection or scattering, and in this embodiment, the L2 is converted from S wave to P wave.

  Therefore, the light converted into the P wave in the L2 passes through the reflective polarizing film 16 and the light diffusion sheet 17 and reaches the liquid crystal display panel 20. On the other hand, the S-wave light that cannot pass through the reflective polarizing film 16 in L2 is reflected again by the reflective polarizing film 16 as indicated by L3 in FIG. 6, and passes through the gap surface 14d of the deflecting optical sheet 12. It passes through and reaches the reflection sheet 15. The light reflected by the reflecting sheet 15 passes through the gap optical surface 12d of the deflecting optical sheet 12 again and passes through the deflecting optical sheet 12. At this time, at least a part of L3 is converted from an S wave to a P wave. The light converted into the P wave in the L3 passes through the reflective polarizing film 16 and the light diffusion sheet 17 and reaches the liquid crystal display panel 20. On the other hand, although illustration and description are omitted below, S-wave light of L3 that cannot be transmitted through the reflective polarizing film 16 is further reflected by the reflective polarizing film 16 and repeatedly reflected or transmitted.

As described above, according to the deflecting optical sheet 12, unlike the light guide plate of the conventional surface light source device, the light is diffused and uniformed, and is sequentially condensed by the prism sheet. Since the light is directly deflected and converged, it can be condensed with high convergence. Thereby, it is possible to improve the light utilization efficiency. In the deflection optical sheet 12, since such deflection is performed over the entire sheet surface, the uniformity of light is also high.
Further, in the deflecting optical sheet 12, by providing the gap surface 14d between the unit prisms 14a, the unit prism 14a does not greatly deflect the optical path brought close to the normal direction of the liquid crystal display panel 20 as described above. The reflected light can pass through the gap surface 14d. Accordingly, as described above, light that could not be used conventionally can also be used as light source light transmitted through the liquid crystal display panel 20.

  That is, according to the deflecting optical sheet 12, the light source light has higher convergence than the conventional one, the light use efficiency of the light source can be increased, and the power consumption can be reduced. Moreover, according to the deflection | deviation optical sheet 12, since a light-guide plate is not needed so that it may show compared with the conventional surface light source device, a member number can be reduced compared with the past, and it can be reduced in thickness and weight. In addition, the manufacturing cost can be directly reduced accordingly.

  Then, according to the surface light source device, the image source module, and the display device to which such a deflection optical sheet 12 is applied, the above-described effects resulting from the deflection optical sheet 12 can be achieved. In particular, according to the surface light source device 10, the image source module 1, and the display device in which the deflecting optical sheet 12 is combined with the reflective polarizing film 16 and the reflecting sheet 15, the above-described effects of the deflecting optical sheet 12 can be more efficiently exhibited. It becomes possible. Further, in the image source module and the display device in which the liquid crystal display panel is combined with the deflection optical sheet 12, the light condensing property and the high efficiency effect of the surface light source device 10 are more remarkably exhibited due to the properties of the liquid crystal display panel. .

  Here, if the surface on the light output side of the surface light source device 10 is a flat surface, the liquid crystal display panel 20 and other layers that may be stacked on the surface light source device 10 can be stably laminated and pasted.

  In the present embodiment, the gap surface 14d of the deflecting optical sheet 12 is a flat surface. However, the present invention is not limited to this, and the gap surface may be a rough surface, a lens shape, or a prism shape different from the unit prism 14a described above. This makes it possible to adjust the light, for example, to control the viewing angle.

  Further, in the present embodiment, the plurality of light sources 11a are arranged in parallel only on one side of the deflecting optical sheet 12, but the plurality of light sources are similarly arranged on the other side of the deflecting optical sheet 12 so as to face the light source 11a. May be paralleled. At this time, the surfaces constituting the unit prism both serve as the light incident surface and the total reflection surface.

FIG. 7 is a diagram for explaining the second embodiment. In the second embodiment, only the orientation of the unit prism in the longitudinal direction of the deflecting optical sheet and the arrangement of the light sources are different from those of the first embodiment, and other descriptions are common to the first embodiment. FIG. 7 shows a diagram corresponding to FIG.
In the second embodiment, in the deflection optical sheet 12 ′, the unit prisms 14a ′ are arranged so that the longitudinal direction thereof is the vertical direction, and the unit prisms 14a ′ are arranged in parallel in the horizontal direction. Accordingly, the longitudinal direction of the gap 14d ′ is also the vertical direction, and the parallel direction is the horizontal direction. The light source 11 ′ is also arranged on the side of the deflecting optical sheet 12 ′, and the plurality of light sources 11a ′ are arranged in parallel in the vertical direction. The description of the deflection optical sheet 12 ′ and the light source 11 ′ other than these is common to the first embodiment.
Even if the orientation is different as in the second embodiment, the deflecting optical sheet 12 ′, the surface light source device including the same, the image display module, and the liquid crystal display device can provide the same effects as those in the first embodiment. To play.

  FIG. 8 is a diagram for explaining the third embodiment. FIG. 8 is a diagram schematically showing the configuration of the video source module 101 included in the display device, and corresponds to FIG. The display device of this embodiment is also a liquid crystal display device, and includes a video source module 101. In addition, although not shown and described, the display device is provided with various known devices for functioning as a liquid crystal display device.

  The video source module 101 includes a surface light source device 110 and a liquid crystal cell 21 and an upper polarizing plate 22 provided on the viewer side of the surface light source device 110. The surface light source device 110 is a device that illuminates the liquid crystal cell 21 from the back side (the side opposite to the observer).

  The surface light source device 110 includes a light source 11, a deflecting optical sheet 12, a reflective sheet 15, and a reflective polarizing film 116. In the present embodiment, the light source 11, the deflection optical sheet 12, the reflection sheet 15, the liquid crystal cell 21, and the upper polarizing plate 22 are the same as those in the first embodiment. In the present embodiment, the second embodiment described above can be applied as the light source and the deflecting optical sheet.

  Similar to the reflective polarizing film 16 described in the first embodiment, the reflective polarizing film 116 transmits light having a specific property (P wave in this embodiment) by utilizing interference of light, It has a property of reflecting light having properties (S wave in this embodiment) and is laminated on the deflection optical sheet 12. Here, the reflective polarizing film 116 has the same function as the lower polarizing plate in that it transmits light (P wave) having a predetermined property. Therefore, the reflective polarizing film 116 includes at least the same function as the lower polarizing plate of the liquid crystal display panel, and the reflective polarizing film 116 can be used as the lower polarizing plate. From this point of view, in this embodiment, the surface light source device 110 is provided with the reflective polarizing film 116 instead of the lower polarizing plate of the liquid crystal display panel. Furthermore, according to the surface light source device 110, as described above, the S-wave can be reflected by the reflective polarizing film 116, and this reflected light can be used again as light source light.

  According to the present embodiment, as can be seen from FIG. 8, the reflector 15, the light source 11, the deflecting optical sheet 12, the reflective polarizing film 116, the liquid crystal cell 21, and the upper polarization from the light source side 11 toward the viewer side. In this configuration, the plates 22 are stacked in this order. That is, since the surface light source device 110 also has the function of a lower polarizing plate, the layer configuration can be simplified in addition to the effects shown in the first embodiment.

DESCRIPTION OF SYMBOLS 1 Image source module 10 Surface light source device 11 Light source 12 Deflection optical sheet 13 Base part 14 Prism part 14a Unit prism 14b Light incident surface 14c Total reflection surface 15 Reflection sheet 16 Reflective polarizing film 17 Light diffusion sheet 20 Liquid crystal display panel 21 Liquid crystal Cell 22 Upper polarizing plate 23 Lower polarizing plate 101 Image source module 110 Surface light source device 116 Reflective polarizing film

Claims (11)

A deflecting optical sheet that deflects light from a light source and emits it in a direction different from the incident light,
A sheet-like base material,
A prism portion having a light incident surface and a total reflection surface that totally reflects light incident from the light incident surface, and a plurality of unit prisms formed to protrude from the base material portion,
The unit prism has a predetermined cross section and extends in one direction, and is arranged in parallel in a direction orthogonal to the extending direction.
When the pitch in the parallel direction of the unit prisms is P (mm) and the parallel direction width of the unit prisms is W (mm),
P> W
This is a deflection optical sheet. When the parallel direction width of the unit prism is W (mm) and the thickness of the base material portion is D (mm),
D ≧ W
The deflection optical sheet according to claim 1, wherein: When the pitch in the parallel direction of the unit prisms is P (mm) and the parallel direction width of the unit prisms is W (mm),
P ≧ 2 ・ W
The deflection optical sheet according to claim 1, wherein: A surface light source device for emitting light to the liquid crystal cell from the back side of the liquid crystal cell,
A light source, and a deflecting optical sheet that enters, deflects, and emits light from the light source, and
The deflection optical sheet includes a sheet-like base material portion, and a prism portion in which a plurality of unit prisms are arranged on the side of the base material portion on which the light source is disposed,
The unit prism includes a light incident surface that allows light from the light source to enter the unit prism, and a total reflection surface that totally reflects light incident from the light incident surface,
The unit prism has a predetermined cross section and extends in one direction, and is arranged in parallel in a direction orthogonal to the extending direction.
When the pitch in the parallel direction of the unit prisms is P (mm) and the parallel direction width of the unit prisms is W (mm),
P> W
Is a surface light source device. When the parallel direction width of the unit prism is W (mm) and the thickness of the base material portion is D (mm),
D ≧ W
The surface light source device according to claim 4, wherein: When the pitch in the parallel direction of the unit prisms is P (mm) and the parallel direction width of the unit prisms is W (mm),
P ≧ 2 ・ W
The surface light source device according to claim 4, wherein:   7. The reflection sheet that reflects light is disposed on the side of the deflection optical sheet where the prism portion is formed, so as to be opposed to the deflection optical sheet. The surface light source device described.   Of the deflecting optical sheet, a reflective polarizing film that transmits only light of a predetermined property and reflects other light is laminated on a surface opposite to the side on which the prism portion is formed. The surface light source device as described in any one of Claims 4-7.   9. An image source module comprising: the surface light source device according to claim 4; and a liquid crystal cell disposed on the opposite side of the surface light source device from the light source.   An image source module comprising the surface light source device according to claim 8, a liquid crystal cell laminated on the reflective polarizing film in the surface light source device, and an upper polarizing plate laminated on the liquid crystal cell.   A liquid crystal display device comprising the video source module according to claim 9.

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