JP2012178272A - Surface light source device, image source module, and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface light source device superior in optical characteristics without using a light guide plate.SOLUTION: The surface light source device has a light source 11, a deflection optical sheet 12, and a reflection sheet 15. The deflection optical sheet is equipped with a prism part 14 in which a plurality of unit prisms 14a are arranged in a row on the side where the light source is arranged. The unit prism has an incident face to make light from the light source incident in the unit prism and a total reflection face to total reflect the light incident from the incident face. The incident face and the total reflection face function as a light emitting face. Each unit prism extends in circular arc shape or in a straight line shape. The plurality of unit prisms are arranged in parallel in a direction different from the direction extending in a concentric shape or straight line shape. The light source emits light inclined in a radial direction of the concentric shape or in a direction in which the unit prisms are arranged in parallel to the prism part; and the reflection sheet is arranged on a side opposite the light source of the deflection optical sheet.

Description

  The present invention relates to a surface light source device used in a display device, an image source module, and a display device including the image source module, and in particular, effectively improves brightness perceived by an observer without using a light guide plate. The present invention relates to a surface light source device, a video source module, and a display device.

  A display device such as a liquid crystal television is provided with a surface light source device that illuminates a liquid crystal display panel from the back side. Surface light source devices are roughly classified into a direct type in which a light source is disposed so as to face one surface of a sheet-like optical member and an edge light type in which a light source is disposed 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.

  In a conventional edge light type surface light source device, a light guide plate for guiding light from the side is provided. Light from the light source enters the light guide plate from the side surface (light incident surface) of the light guide plate, is repeatedly reflected in the light guide plate, and is directed toward the surface facing the light incident surface (light guide direction). Proceed through the light plate. At that time, the light traveling in the light guide plate is gradually emitted from the light exit surface as it proceeds 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 the 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 to this, as an optical performance of the surface light source device, there is a demand that light from the light source is efficiently deflected and converged to increase luminance with high energy efficiency.

  Therefore, if sufficient light deflection and convergence can be achieved without using a light guide plate, the weight of the surface light source device, and the image source module and display device using the surface light source device, and the optical characteristics can be reduced. .

  In view of the above problems, an object of the present invention is to provide a surface light source device having excellent optical characteristics without using a light guide plate. In addition, an image source module including the surface light source device and a liquid crystal display device are provided.

  The present invention will be described below. Here, for ease of understanding, reference numerals in the drawings are given in parentheses as an example, but the present invention is not limited thereto.

  The invention according to claim 1 is a surface light source device (10) for emitting light from the back side of the liquid crystal display panel (20) to the liquid crystal display panel, and the light source (11) and light from the light source are incident on the surface light source device (10). And a deflecting optical sheet (12) that deflects and emits light, and a reflecting sheet (15) that can reflect light, and the deflecting optical sheet has a plurality of unit prisms (14a) on the side where the light source is disposed. The unit prism has an 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 incident surface. The incident surface and the total reflection surface also function as a light exit surface. Each unit prism extends in an arc shape or a straight line, and the plurality of unit prisms are arranged in parallel in a direction different from the direction extending concentrically or linearly. Is a concentric radial direction or unit The light which is inclined in parallel with the direction from which the rhythm is emitted to the prism portion, the reflective sheet, the deflection optical sheet of the light source is disposed at the side where the opposite side, a surface light source device.

  Here, “the back side of the liquid crystal display panel” is the side opposite to the observer side, that is, the side on which the light source is arranged.

  According to a second aspect of the present invention, in the surface light source device (10) according to the first aspect, the deflection optical sheet (12) is based on a side of the prism portion (14) opposite to the light source (11) side. It has the material part (13), It is characterized by the above-mentioned.

  According to a third aspect of the present invention, in the surface light source device (10) according to the first or second aspect, the surface of the deflecting optical sheet (12) is predetermined so as to face the surface on which the prism portion (14) is provided. A light diffusing sheet (17) is provided, which has a gap of 2 and can diffuse and transmit light.

  According to a fourth aspect of the present invention, in the surface light source device (10) according to any one of the first to third aspects, the base portion (13) and the prism portion (14) are integrally formed. It is characterized by that.

  The invention according to claim 5 is the surface light source device (10) according to any one of claims 1 to 4, and the incident surface (14b) of the deflecting optical sheet (12) and all of the surface light source device. It is an image source module (1) having a liquid crystal display panel (20) arranged on the side where the reflecting surface (14c) is formed.

  A sixth aspect of the present invention is a liquid crystal display device comprising the video source module according to the fifth aspect.

  According to the present invention, the surface light source device, the video source module using the surface light source device, and the liquid crystal display device can be reduced in weight without using a light guide plate. Further, even with such a configuration, it is possible to improve the light convergence as compared with the conventional case.

It is a figure explaining 1st embodiment and is an exploded perspective view of an image source module. It is a figure which shows the cross section along the line shown by II-II in FIG. It is the figure which looked at FIG. 1 from the direction of arrow III. 4A and 4B are diagrams for explaining the second embodiment, in which FIG. 4A is a view from the same viewpoint as FIG. 2 and FIG. 4B is a view from the same viewpoint as FIG. FIG. 5A is a diagram for explaining a third embodiment, FIG. 5A is a diagram from the same viewpoint as FIG. 2, and FIG. 5B is a diagram from the same viewpoint as FIG. 3. It is a schematic diagram showing a part of manufacturing process of the deflection | deviation optical sheet in 3rd embodiment. FIGS. 7A and 7B are views for explaining a fourth embodiment, in which FIG. 7A is a view from the same viewpoint as FIG. 2 and FIG. 7B is a view from the same viewpoint as FIG. FIGS. 8A and 8B are diagrams for explaining a fifth embodiment, in which FIG. 8A is a view from the same viewpoint as FIG. 2 and FIG. 8B is a view from the same viewpoint as FIG. It is a figure explaining a surface light source device among 6th embodiment, and is a figure from the viewpoint similar to FIG. It is a figure explaining 7th embodiment and is a figure equivalent to FIG. It is the figure which expanded and showed a part of 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. Moreover, in each embodiment described below, an optical path example is represented by an arrow using a drawing, but the optical path example represented by this arrow is a conceptual one for explanation, for example, refraction or reflection. It is not an exact representation of the degree.

  1-3 is a figure for demonstrating 1st embodiment. FIG. 1 is an exploded perspective view schematically showing a configuration of a video source module 1 included in a display device. FIG. 2 is a cross-sectional view of the video source module 1 along the line indicated by 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. In FIGS. 1 and 2, the right side of the drawing is the observer side. FIG. 3 is a view of the deflecting optical sheet 12 and the light source 11 as viewed from the observer side. 1 to 3 and the drawings shown below may be shown by changing or exaggerating the shape of each part for easy understanding, and repeated reference numerals may be omitted. The first embodiment will be described 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 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 and 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 deflection optical sheet 12, a reflection sheet 15, 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. The light source 11 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 is disposed. Therefore, as can be seen from FIGS. 2 and 3, light is emitted from the light source 11 with spreading in the vertical and horizontal directions (see L1 to L6). Specifically, the light source 11 emits light toward the prism unit 14 so as to be inclined in a direction in which unit prisms 14a included in the prism unit 14 described later are arranged (radial direction of concentric circles).

  The deflection optical sheet 12 has a function of deflecting light projected obliquely from the light source 11 and condensing the light so as to approach the normal direction of the liquid crystal display panel 20 by being combined with a reflection sheet 15 described later. is doing. Therefore, as clearly shown in FIG. 2, 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.

  Here, the light source 11 is arranged closer to the viewer side than the deflecting optical sheet 12. That is, the light from the light source 11 is emitted so as to be inclined in the direction in which the unit prisms 14a are arranged, but the inclination direction is opposite to the observer side.

  The base material part 13 is a part to be a base material for forming the prism part 14 and supports the prism part 14 so that deformation of the prism part 14 can be prevented. From this point of view, specific examples of the material forming 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, and the surfaces forming the hypotenuses refract the incident light and make the incident light into the unit prism 14a and totally reflect the incident light. The total reflection surface 14c is configured. Further, the incident surface 14b and the total reflection surface 14c also function as a light exit surface. The optical path will be described later.

  The incident surface 14b is the surface facing the light source 11, and the total reflection surface 14c is the opposite surface. As can be seen from FIG. 3, in the present embodiment, each unit prism 14a extends in an arc shape, and the plurality of unit prisms 14a are arranged concentrically. In the present embodiment, the center of the concentric circle is located below the sheet surface of the deflecting optical sheet 12 and at the center in the sheet lateral direction.

  The material forming the prism portion 14 is not particularly limited, but is widely used as a material for an optical sheet incorporated in a display device, and has excellent mechanical characteristics, optical characteristics, stability, workability, and the like, and is inexpensive. It is preferable to use a material that can be obtained. Examples thereof include transparent resins mainly composed of one or more of acrylic, styrene, polycarbonate, polyethylene terephthalate, acrylonitrile, etc., and epoxy acrylate and urethane acrylate-based reactive resins (ionizing radiation curable resins, etc.). it can.

As described above, since the deflecting optical sheet 12 projects light from the light source 11 from an oblique direction, the light enters the unit prisms 14a at different angles. Here, the deflecting optical sheet 12 has a function of deflecting light and bringing the light closer to the normal line direction of the liquid crystal display panel 20 (condensing light). Accordingly, each unit prism 14a can have a shape for realizing such a function. For example, the angle formed by the light incident from the incident surface 14b of a unit prism 14a with the normal direction of the liquid crystal display panel 20 is θ ₁ (see FIG. 2), and the light reflected by the total reflection surface 14c is the method of the liquid crystal display panel 20. When the angle formed with the linear direction is θ ₂ , the apex angle formed by the incident surface 14b and the total reflection surface 14c of the unit prism 14a is λ (see FIG. 2), and the refractive index of the unit prism 14a is n. Of the prism 14a, the angle φ (see FIG. 2) formed by the total reflection surface 14c and the panel surface of the liquid crystal display panel 20 can be obtained by the following equation (1).

  Therefore, the angle of the reflected light by the total reflection surface 14c can be adjusted by adjusting these relationships.

  On the other hand, as described above, both the incident surface 14b and the total reflection surface 14c also function as a light exit surface. Therefore, it is preferable that the prism portion 14 has a shape that deflects light so as to approach the normal direction of the liquid crystal display panel 20 even when the light exits from the incident surface 14b and the total reflection surface 14c.

  That is, the unit prism 14a preferably has a shape having both a function as an incident surface and a total reflection surface and a function as a light exit surface. Thereby, condensing property can be improved. A specific unit prism 14a for that purpose is not particularly limited as long as the function can be realized, but preferably has a triangular cross section as in the present embodiment.

  In the case of the prism portion 14 of the present embodiment, as can be seen from the above formula (1), 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 angles λ and φ of each unit prism 14a may be different depending on the position where the unit prism 14a is disposed. However, the present invention is not limited to this, and the apex angle λ of all the unit prisms may be the same angle.

Here, in the surface light source device, it is sufficient that the light from the light source 11 is appropriately irradiated over the entire surface of the prism portion 14, and there is no particular limitation. However, from the viewpoint of thinning, θ ₁ can be increased as much as possible. preferable. From this viewpoint, θ ₁ is preferably 60 ° or more and 85 ° or less.

  Such a deflecting optical sheet 12 can be manufactured, for example, by shaping or sticking the prism portion 14 on the base material portion 13. At that time, the material forming the prism portion 14 and the material forming the base material portion 13 may be different or the same.

The reflection sheet 15 is a sheet-like member laminated on the surface of the base portion 13 of the deflecting optical sheet 12 opposite to the side where the prism portion 14 is disposed, and has a function of reflecting light. is doing. Here, the reflection may be any of specular reflection and diffuse reflection, but is preferably diffuse reflection. By diffusely reflecting, the reflected light can be made more uniform, and the uniformity of the emitted light as the surface light source device can be improved. Further, by diffusely reflecting, it is possible to suppress the light emitted from the light source 11 from going back in the same optical path and returning to the light source 11 again.
As long as the reflection sheet 15 has a function of reflecting light as described above, the type thereof is not particularly limited, and a known sheet can be applied.

The light diffusion sheet 17 is a sheet-like member having a function of diffusing and transmitting the light emitted from the deflecting optical sheet 12. Specifically, light that has been strongly converged due to the action of the deflecting optical sheet 12 and has increased directivity is diffused to some extent, the luminance distribution is expanded, and the viewing angle is expanded.
The light diffusing sheet 17 is disposed closer to the viewer than the light source 11. That is, as can be seen from FIGS. 1 and 2, the light diffusion sheet 17 is disposed on the viewer side with a predetermined gap from the deflection optical sheet 12. The light from the light source 11 is irradiated toward this gap.

  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 forming the main part is not particularly limited, but 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, etc. It is preferable that the material is available at low cost. This includes, for example, transparent resins mainly composed of one or more of acrylic, styrene, polycarbonate, polyethylene terephthalate, acrylonitrile, etc., epoxy acrylate and urethane acrylate reactive resins (ionizing radiation curable resins, etc.), etc. Can do. On the other hand, examples of the light scattering agent include silica (silicon dioxide), alumina (aluminum oxide), acrylic resin, polycarbonate resin, silicone resin, barium sulfate, titanium oxide and the like having an average particle diameter of about 0.5 μm to 100 μm. Can be mentioned.

  Here, 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. Since the upper and lower polarizing plates 22 and 23 decompose the incident light into two orthogonal polarization components (P wave and S wave), the polarization component in one direction (direction parallel to the transmission axis) (for example, P wave) ) And absorbs a polarization component (for example, S wave) in the other direction (direction parallel to the absorption axis) perpendicular to the one direction.

  The liquid crystal cell 21 is configured so that an electric field can be applied to each region where one pixel is formed, and the orientation of the liquid crystal cell 21 to which the electric field is applied changes. When a polarized component in a specific direction (P wave in the present embodiment) 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 or is absorbed by the upper polarizing plate 22. It is possible to control whether it is blocked.

  In this way, the liquid crystal display panel 20 is configured to display an image 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 FIGS. FIG. 2 shows optical path examples L1 and L2, and FIG. 3 shows optical path examples L3 to L6.

The light emitted from the light source 11 enters the incident surface 14b of the deflecting optical sheet 12 while spreading radially, and is totally reflected by the total reflection surface 14c and deflected so that its direction approaches the normal direction of the surface of the liquid crystal display panel 20. (L1 to L6). However, the direction is the opposite side to the liquid crystal display panel 20 (the opposite side to the observer side). The light (L1, L2) totally reflected by the total reflection surface 14c passes through the prism portion 14 and the base material portion 13, reaches the reflection sheet 15, and is reflected here. The light reflected by the reflection sheet 15 is changed in direction toward the observer, passes through the prism portion 14 again, and exits from the incident surface 14b and the total reflection surface 14c functioning as a light exit surface. When the light exits, a part of the light further approaches the normal direction of the liquid crystal display panel 20 due to refraction.
Here, if the reflection sheet 15 is a sheet that can be diffusely reflected, the light reflected by the reflection sheet 15 diffuses and spreads, and the uniformity of the light emitted from the deflecting optical sheet 12 is enhanced. Further, by performing diffuse reflection, it is possible to prevent light emitted from the light source 11 from following the same optical path and returning to the light source 11 again, thereby improving the light utilization efficiency.

  According to the prism portion 14 and the reflection sheet 15 of the surface light source device 10, the light is diffused and uniformed as in the light guide plate of the conventional surface light source device, and the light is sequentially collected by the prism sheet. In contrast, since the light from the light source 11 is directly deflected and converged, the light can be condensed with high convergence. Accordingly, it is possible to increase the light use efficiency. The deflecting optical sheet 12 deflects such light over the entire surface of the sheet, so that it can be an excellent surface light source.

  Light (L1, L2) emitted from the deflecting optical sheet 12 passes through the light diffusion sheet 17 and exits. At that time, the light diffusion sheet 17 can widen the angular luminance distribution of the light that has been strongly converged due to the action of the deflecting optical sheet 12 and has increased directivity as described above, and the viewing angle can be expanded to some extent. .

  According to such a surface light source device 10, the light convergence is higher than that of the conventional surface light source device, the light use efficiency of the light source can be increased, and the power consumption can be reduced. Further, as can be seen in comparison with the conventional surface light source device, the surface light source device 10 does not require a light guide plate or a plurality of light condensing sheets, so that the number of members can be reduced compared with the conventional surface light source, making it thinner and lighter. It is. In addition, the manufacturing cost can be directly reduced accordingly.

  According to the video source module 1 and the display device to which the surface light source device 10 is applied, the above-described effects resulting from the surface light source device 10 can be achieved. In particular, in the video source module 1 and the display device in which the surface light source device 10 is combined with the liquid crystal display panel 20, the effects of light condensing and high efficiency of the surface light source device 10 are more prominent due to the properties of the liquid crystal display panel 20. It becomes possible to do.

  Further, if the light-emitting side surface of the surface light source device 10 (the surface of the light diffusion sheet 17 on the liquid crystal display panel 20 side) is a flat surface, the surface light source device 10 may be laminated on the liquid crystal display panel 20 or other surface light source devices 10. It can be laminated and affixed stably to the layer.

  FIG. 4 shows a diagram for explaining the second embodiment. In the second embodiment, only the number and arrangement of light sources in the surface light source device are different from those in the first embodiment, and other parts are common. Therefore, FIG. 4 shows the light source 31 and the deflection optical sheet 12 in the second embodiment. 4A is a view from the same viewpoint as FIG. 2, and FIG. 4B is a view from the same viewpoint as FIG. Further, in FIG. 4, although not particularly indicated, examples of optical paths are shown by solid line, broken line, and dotted line arrows.

  In the second embodiment, the light source 31 includes a plurality of unit light sources 31a. The unit light sources 31a are arranged side by side at the same height position. As a result, the luminance distribution can be made more uniform, particularly in the horizontal direction of the screen. Each unit light source 31a is common to the light source 11 described above.

  FIG. 5 shows a diagram for explaining the third embodiment. In the third embodiment, the shape of the light source and the deflection optical sheet in the surface light source device is different from that of the first embodiment described above, and the other parts are common. FIG. 5 shows the light source 41 and the deflecting optical sheet 42 in the third embodiment. 5A is a view from the same viewpoint as FIG. 2, and FIG. 5B is a view from the same viewpoint as FIG. In addition, in FIG. 5, an optical path example is shown by a solid line arrow although no reference numeral is given.

  The light source 41 provided in the third embodiment has a plurality of unit light sources 41a arranged in a horizontal direction. Each unit light source 41a is a device that projects light to the deflection optical sheet 42 from obliquely below. Each unit light source 41a 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 is disposed. Specifically, as can be seen from FIG. 5A, each unit light source 41a emits light toward the prism portion 44 so as to be inclined in a direction in which unit prism portions 44a described later are arranged in parallel.

  On the other hand, the deflection optical sheet 42 provided in the third embodiment has a function of deflecting light projected obliquely from the light source 41 and bringing it closer (condensing) in the normal direction of the liquid crystal display panel 20. . As shown in FIG. 5A, the deflection optical sheet 42 of the present embodiment includes a base material portion 13 and a prism portion 44, and the prism portion 44 is provided with a plurality of unit prisms 44a. . Since the base material part 13 is common with 1st embodiment, description is abbreviate | omitted.

  The prism part 44 is a part having a plurality of unit prisms 44a. Each unit prism 44a has a portion having a substantially triangular cross section, and the surfaces forming the oblique sides refract the incident light, and the incident surface 44b for entering the light into the unit prism 44a and the incident light are totally reflected. The total reflection surface 44c is configured. Further, the incident surface 44b and the total reflection surface 44c also function as a light exit surface. Further, as can be seen from FIG. 5B, the unit prism 44a has a cross section shown in FIG. 5A and extends in the horizontal direction, and the plurality of unit prisms 44a are orthogonal to the extending direction. Parallel to the direction to be.

  Here, the light source 41 is disposed closer to the observer than the deflecting optical sheet 42. That is, the light from the light source 41 is emitted so as to incline in the direction in which the unit prisms 44a are arranged, but the inclining direction is opposite to the observer side.

  The material forming the prism portion 44 is not particularly limited, but is the same as that of the prism portion 14 described above.

Regarding the cross-sectional shape of the unit prism 44a, the same concept as that of the unit prism 14a of the first embodiment can be used, and the description thereof is omitted here. As indicated by solid arrows in FIG. 5, the light emitted from each unit light source 41a is incident from the incident surface 44b of the deflecting optical sheet 42 while spreading over almost the entire region in the direction in which the unit prisms 44a are arranged in parallel. The light is totally reflected by the total reflection surface 44c and deflected so that its direction approaches the normal direction of the surface of the liquid crystal display panel 20.
However, the direction is the opposite side to the liquid crystal display panel 20 (the opposite side to the observer side). The light totally reflected by the total reflection surface 44c passes through the prism portion 44 and the base material portion 13, reaches the reflection sheet 15, and is reflected there. The direction of the light reflected by the reflection sheet 15 is changed to the viewer side, passes through the prism portion 44 again, and exits from the incident surface 44b and the total reflection surface 44c functioning as the light exit surface. When the light exits, a part of the light further approaches the normal direction of the liquid crystal display panel 20 due to refraction.

  After the light is emitted from the deflecting optical sheet 42, the light is emitted from the surface light source device as in the first embodiment.

  Such a surface light source device having a light source and a deflecting optical sheet, an image source module, and a display device can also achieve the effects described in the first embodiment.

  Further, the deflecting optical sheet 42 has the cross section shown in FIG. 5A extending in a straight line in the longitudinal direction. Accordingly, it is possible to perform continuous production by molding using a mold roll or the like, and the productivity is excellent. FIG. 6 is a diagram schematically illustrating a part of the process for an example of the manufacturing method of the deflecting optical sheet 42.

  When the deflecting optical sheet 42 is manufactured, as shown in FIG. 6, the prism portion 44 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 44, a mold roll 300 having a groove having a shape corresponding to the shape of the prism portion 44 at a predetermined pitch is prepared. Next, the base material 13 ′ is fed between the mold roll 300 and the nip roll 301. An arrow VI shown in FIG. 6 is a direction in which the base material 13 ′ is fed. In accordance with the feeding of the base material 13 ′, droplets of the composition 304 constituting the prism portion 44 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 44. After the prism portion 44 is formed, the sheet is pulled from the mold roll 300 by being pulled using the peeling roll 307.

  However, the deflecting optical sheet 42 in the present embodiment is not necessarily limited to the manufacturing by shaping as described above, and may be extrusion molding. In this case, the base material portion 13 and the prism portion 44 are integrated.

  Since such a linear prism portion does not have a deflecting property and a light collecting property in the left-right direction, the plurality of unit light sources 41a are arranged along the extending direction of the unit prism 44a as in the present embodiment. Parallel. This makes it possible to obtain luminance uniformity in the horizontal direction.

  FIG. 7 shows a diagram for explaining the fourth embodiment. In the fourth embodiment, the shape of the light source and the deflecting optical sheet in the surface light source device is different from that of the first embodiment described above, and the other parts are common. FIG. 7 shows the light sources 41 and 51 and the deflecting optical sheet 52 in the fourth embodiment. 7A is a view from the same viewpoint as FIG. 2, and FIG. 7B is a view from the same viewpoint as FIG. In addition, in FIG. 7, an optical path example is shown by a solid line and a dotted line arrow although no reference numerals are given.

The light source provided in the fourth embodiment has a light source 51 in addition to the light source 41 provided in the third embodiment described above. In the light source 51, a plurality of unit light sources 51a are arranged along the extending direction of a unit prism 54a described later. Each unit light source 51 a is a device that projects light source light obliquely from above to the deflecting optical sheet 52. Similar to the light source 41, the light source 51 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 unit light source 51a emits light that spreads in the vertical direction and has little spread in the horizontal direction, as can be seen from the dotted arrows in FIG. That is, the light source 51 emits light toward the prism portion 54 so as to be inclined in a direction in which unit prisms 54a described later are arranged in parallel.
As can be seen from the above description, in the fourth embodiment, light is emitted to the deflecting optical sheet 52 from both below and above.

  On the other hand, the deflection optical sheet 52 provided in the fourth embodiment is similar to the deflection optical sheet 42 provided in the third embodiment, and a plurality of unit prisms having a base portion 13 and a portion having a substantially triangular cross section. The prism part 54 which comprises 54a is provided. Each unit prism 54a has a cross section and extends linearly, and the plurality of unit prisms 54a are arranged in parallel in a direction orthogonal to the extending direction.

  Here, the light sources 41 and 51 are arranged closer to the observer than the deflecting optical sheet 52. That is, the light from the light sources 41 and 51 is emitted so as to incline in the direction in which the unit prisms 54a are arranged, but the inclining direction is opposite to the observer side.

  However, in the present embodiment, since the light sources 41 and 51 are provided on both the lower side and the upper side, the surfaces 54b and 54c forming the hypotenuse having a substantially triangular cross section are formed so as to serve as the incident surface and the total reflection surface, respectively. The That is, the surface 54 c is a total reflection surface for the light source 41, but is an incident surface for the light source 51. On the other hand, the surface 54 b is an incident surface with respect to the light source 41, but is a total reflection surface with respect to the light source 51. Therefore, the shape of the unit prism 54a is configured based on the concept described in the first embodiment for both the surfaces 54b and 54c. Similarly to the above, the surfaces 54b and 54c also have a function as a light emitting surface.

  As indicated by solid line arrows in FIG. 7, the light emitted from the light source 41 enters from the surface 54b of the deflecting optical sheet 52 and is totally reflected by the surface 54c so that the direction approaches the normal direction of the liquid crystal display panel. Deflected. At this time, the direction is the direction toward the side opposite to the observer side. The light is reflected by the reflecting sheet 15 and emitted from the deflecting optical sheet 52. On the other hand, as shown by the dotted line in FIG. 7, the light emitted from the light source 51 enters from the surface 54c of the deflecting optical sheet 52 and is totally reflected by the surface 54b so that the direction approaches the normal direction of the liquid crystal display panel. Deflected. At this time, the direction is the direction toward the side opposite to the observer side. The light is reflected by the reflecting sheet 15 and emitted from the deflecting optical sheet 52.

  By providing the light sources 41 and 51 and the deflecting optical sheet 52, the same effects as those of the third embodiment described above can be obtained. In addition to this, since the light sources are arranged in the vertical direction, the luminance distribution in the vertical direction can be made more uniform.

  FIG. 8 is a diagram for explaining the fifth embodiment. In the fifth embodiment, the light source and the deflecting optical sheet in the surface light source device are different from those in the first embodiment described above, and the other parts are common. FIG. 8 shows the light source 61 and the deflecting optical sheet 62 in the fifth embodiment. 8A is a view as seen from the same viewpoint as FIG. 2, and FIG. 8B is a view as seen from the same viewpoint as FIG. Further, in FIG. 8, an optical path example is shown by a solid line arrow although no reference numeral is given.

  The light source 61 provided in the fifth embodiment is a device that projects light from obliquely above the deflecting optical sheet 62. The light source 61 includes a light emitting source 61a and a condensing reflection member 61b. The light emission source 61a includes an LED (light emitting diode), an incandescent light bulb, or the like, and an optical system for enlarging and projecting light emitted from the light emission source is disposed. Specifically, as can be seen from FIG. 8, the light emission source 61a emits light with a spread in the vertical direction and the horizontal direction. Therefore, in this embodiment, there may be one light source.

The condensing and reflecting member 61b functions as a part of the light source, is provided above the deflecting optical sheet 62, has a predetermined shape as shown in FIG. 8B, and can reflect the light from the light emitting source 61a. It is the member formed in. More specifically, the condensing / reflecting member 61b receives and reflects light from the light source 61a. At this time, the light from the light source 61a spreading in the horizontal direction is condensed and spread in the horizontal direction. Are parallel and can be reflected (see FIG. 8B). And it is set as the light orthogonal to the extension direction of the unit prism 64a mentioned later.
As a result, even the linear unit prism 64a can be deflected into light that can be properly totally reflected.

  On the other hand, the deflection optical sheet 62 provided in the fifth embodiment has a function of deflecting light emitted obliquely from the light source 61 and bringing it closer (condensed) in the normal direction of the liquid crystal display panel 20. . The deflection optical sheet 62 according to the present embodiment includes a base material portion 13 and a prism portion 64 as shown in FIG. 8, and the prism portion 64 is provided with a plurality of unit prisms 64a. Since the base material part 13 is common with 1st embodiment, description is abbreviate | omitted.

  The light source 61 is disposed closer to the observer than the deflecting optical sheet 62. That is, the light from the light source 61 is emitted so as to incline in the direction in which the unit prisms 64a are arranged, but the inclining direction is opposite to the observer side.

The prism part 64 is a part having a plurality of unit prisms 64a. Each unit prism 64a has a portion having a substantially triangular cross section, and has surfaces 64b and 64c forming the hypotenuse. The surface 64b is a surface on the light emission source 61a side, and the surface 64c is a surface on the opposite side. Here, in the present embodiment, the surface 64c is an incident surface, and the surface 64b is a total reflection surface. Further, similarly to the above, the surfaces 64c and 64b also function as light exit surfaces.
Further, as can be seen from FIG. 8B, the unit prism 64a has a cross section shown in FIG. 8A and is a straight line extending in the horizontal direction, and the plurality of unit prisms 64a are orthogonal to the extending direction. To be in parallel.

  That is, according to the present embodiment, light is emitted from the light emitting source 61a as shown by the solid line arrow in FIG. At this time, there is a spread in both the horizontal direction and the vertical direction. Such light is reflected by the condensing reflection member 61b. At this time, the light spread in the vertical direction is maintained by the action of the condensing reflection member 61b, while the light spread in the horizontal direction is deflected and parallelized. That is, the light is irradiated toward the prism portion 64 while being inclined in the parallel direction of the unit prisms 64a. The reflected light from the condensing reflection member 61b enters from the surface 64c of the deflecting optical sheet 62, is totally reflected by the surface 64b, and is deflected so that the direction approaches the normal direction of the liquid crystal display panel. At this time, the direction is the direction toward the side opposite to the observer side. The light is reflected by the reflecting sheet 15 and emitted from the deflecting optical sheet 62.

  In the present embodiment, the effects described in the first embodiment can be achieved, and the linear prism portion 64 can be applied while using only one light source 61a.

  FIG. 9 is a diagram for explaining the sixth embodiment. In the sixth embodiment, the configuration of the deflecting optical sheet in the surface light source device is different from that of the first embodiment described above, and the other parts are common. FIG. 9 shows the light source 11 and the deflecting optical sheet 72 in the sixth embodiment. FIG. 9 is a view from the same viewpoint as FIG. Further, in FIG. 9, an example of an optical path is shown by a solid line arrow although no reference numeral is given.

  The deflection optical sheet 72 is different from the deflection optical sheet 12 in that a gap is provided between the base material portion 13 and the reflection sheet 15 and an air layer IX is provided. The structure of each part and other arrangement | positioning are common in 1st embodiment.

By providing such an air layer IX, as can be seen from FIG. 9, refraction occurs at the interface between the base member 13 and the air layer IX at the time of light emission and light incident. Further, the distance from incident light to outgoing light is increased by the thickness of the air layer IX. Thereby, the light can be emitted at a position farther from the incident position (position A) of the light to the deflecting optical sheet 72 (position B), and the emitted light is prevented from being concentrated at a predetermined location. Is possible. That is, the uniformity of the light emitted as the surface light source device can be improved.
Moreover, when the reflection sheet 15 is a sheet that can be diffusely reflected as described above, the reflected light can be further uniformed, and the uniformity of the emitted light can be improved as a surface light source device.

  10 and 11 are diagrams for explaining the seventh embodiment. FIG. 10 is a diagram corresponding to FIG. 2 in the present embodiment. 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 includes various devices for functioning as a liquid crystal display device.

  In this embodiment, in addition to the surface light source device 10 and the liquid crystal display panel 20 described above, the video source module 101 is provided with a viewing angle widening member 120. Since the surface light source device 10 and the liquid crystal display panel 20 are as described above, description thereof is omitted here. Note that the surface light source device is not limited to the surface light source device 10, and any surface light source device of each embodiment described so far can be applied here.

  The viewing angle widening member 120 is a member that is attached to the observer side of the liquid crystal display panel 20, that is, the upper polarizing plate 22, and is a layer that has a function of diffusing light and widening the viewing angle. Specifically, it is as follows.

  The field expansion member 120 includes a transmission part 121 and an intermediate part 122 provided between the transmission parts 121. The transmission part 121 and the interposition part 122 have a cross section shown in FIG. 10 and have a shape extending to the back / near side of the drawing. FIG. 11 shows an enlarged view of a part of the visual field enlarging member 120.

  The transmission part 121 is a part whose main function is to transmit light. In the cross section shown in FIG. 10 and FIG. 11, a long lower bottom on the liquid crystal display panel 20 side and a short upper side on the opposite side (observer side). An element having a substantially trapezoidal cross-sectional shape having a bottom. The transmission parts 121 are arranged at predetermined intervals along the sheet surface, and an intermediate part 122 having a substantially triangular cross section is formed therebetween. Therefore, the intermediate portion 122 has a triangular cross section having a base on the upper bottom side of the transmission portion 121 and a vertex facing the bottom side of the transmission portion 121, and is filled with a predetermined material. As a result, the interspace 122 is formed.

In the present embodiment, the intermediate portion 122 has a triangular cross section, but the present invention is not limited thereto, and the intermediate portion may have a trapezoidal cross section. At this time, a lower bottom with a long intermediate portion is disposed on the short upper bottom side of the transmission portion 121, and a short upper bottom with a short intermediate portion is disposed on the long lower bottom side of the transmission portion 121.
Further, in the present embodiment, an example in which the hypotenuse forming the triangular cross section is a straight line is shown, but the present invention is not limited to this, and the hypotenuse may be a polygonal line or a curved line.

  Here, the intermediate portion 122 is filled with a material having a refractive index smaller than that of the transmission portion 121. The refractive index difference is not particularly limited, but is preferably greater than 0 and 0.15 or less. By increasing the refractive index difference, more light can be reflected and diffused.

  That is, as indicated by a dotted arrow in FIG. 11, a part of the light transmitted through the liquid crystal display panel 20 reaches the interface between the transmission part 121 and the intermediate part 122. Since the refractive index difference as described above is provided between the transmission part 121 and the inter-part 122, the light reaching the interface is totally reflected based on the refractive index difference and the incident angle to the interface. Furthermore, since the transmission part 121 and the intermediate part 122 have the shapes as described above, the interface is inclined with respect to the sheet normal. Accordingly, the totally reflected light is deflected and emitted in the diffusing direction. As a result, light is diffused and the viewing angle can be enlarged.

  As described so far, the surface light source devices of the above-described embodiments have high light condensing properties, and thus the condensed light can efficiently pass through the liquid crystal display panel 20. According to the present embodiment, the light transmitted through the liquid crystal display panel 20 can be efficiently diffused in this way, and the viewing angle can be widened. Accordingly, it is possible to provide an image source module and a display device having a wider viewing angle.

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 15 Reflection sheet 17 Light diffusion sheet 20 Liquid crystal display panel 21 Liquid crystal cell 22 Upper polarizing plate 23 Lower polarizing plate

Claims (6)

A surface light source device for emitting light to the liquid crystal display panel from the back side of the liquid crystal display panel,
A light source, a deflecting optical sheet that enters, deflects, and emits light from the light source, and a reflective sheet that can reflect the light, and
The deflecting optical sheet includes a prism portion in which a plurality of unit prisms are arranged on the side where the light source is disposed,
The unit prism has an 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 incident surface.
The incident surface and the total reflection surface also function as a light exit surface,
Each of the unit prisms extends in an arc shape or linearly, and the plurality of unit prisms are arranged in parallel to a direction different from a direction extending concentrically or in the linear shape,
The light source emits light inclined to the concentric radial direction or the parallel direction of the unit prisms to the prism unit,
The reflective sheet is disposed on a side opposite to the light source of the deflecting optical sheet,
Surface light source device.   The surface light source device according to claim 1, wherein the deflecting optical sheet has a base material portion on a side opposite to the light source side in the prism portion.   A light diffusing sheet that diffuses and transmits light is disposed with a predetermined gap so as to face the surface of the deflecting optical sheet on which the prism portion is provided. Item 3. The surface light source device according to Item 1 or 2.   The surface light source device according to claim 1, wherein the base portion and the prism portion are integrally formed.   5. A surface light source device according to claim 1, and a liquid crystal display panel disposed on a side of the surface light source device on which the incident surface and the total reflection surface of the deflection optical sheet are formed. Having video source module.   A liquid crystal display device comprising the video source module according to claim 5.

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