JP2010061863A - Illuminating device and method of manufacturing the same, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a low cost illuminating device excellent in a light-emitting quality; a method of manufacturing the same; and a display device using the illumination device. <P>SOLUTION: In the illuminating device which includes a cold-cathode fluorescent tube (a light source) and a diffusing plate 15 for diffusing light from the cold-cathode fluorescent tube, a convex part 15b1 and a concave part 15b2 are arranged on a surface 15b of the diffusing plate 15 on a side of the cold-cathode fluorescent tube. Then, in the illuminating device, there is formed a reflecting part 21 for reflecting the light on a side of the cold-cathode fluorescent tube against the convex part 15b1 of the diffusing plate 15. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lighting device used for a backlight or the like, a manufacturing method thereof, and a display device using the lighting device.

  In recent years, for example, in a television receiver for home use, as represented by a liquid crystal display device, a display device provided with a liquid crystal panel as a flat display portion having many features such as a thinner and lighter than a conventional cathode ray tube. Is becoming mainstream. Such a liquid crystal display device includes an illumination device (backlight) that emits light, and a liquid crystal panel that displays a desired image by serving as a shutter for light from a light source provided in the illumination device. Is provided. In the television receiver, information such as characters and images included in the video signal of the television broadcast is displayed on the display surface of the liquid crystal panel.

  The illumination device is roughly classified into a direct type and an edge light type depending on the arrangement of the light source with respect to the liquid crystal panel. However, a liquid crystal display device having a liquid crystal panel of 20 inches or more is higher than the edge light type. A direct-type illumination device that is easy to increase in luminance and size is generally used. In other words, the direct type lighting device is configured by arranging a plurality of light sources on the back (non-display surface) side of the liquid crystal panel, and since a light source can be arranged immediately behind the liquid crystal panel, a large number of light sources are used. Therefore, it is easy to obtain high luminance and suitable for high luminance and large size. In addition, the direct type illumination device is suitable for high luminance and large size because the inside of the device has a hollow structure and is light even if it is large.

In addition, in a conventional lighting device, for example, as described in Patent Document 1 below, a plurality of cold cathode fluorescent tubes as light sources are provided, and a diffusion plate that diffuses light from these cold cathode fluorescent tubes is installed. Thus, it has been proposed to irradiate the liquid crystal panel with light through a diffusion plate. In addition, in this conventional illumination device, by forming a printed film made of UV curable light-shielding ink on the surface of the diffuser plate facing the cold cathode fluorescent tube, the planar light emitted from the diffuser plate is changed. It was possible to prevent uneven brightness from occurring. That is, in this conventional illuminating device, an image (lamp image) of the cold cathode fluorescent tube appears on the printed film by providing the printed film on the surface of the diffusion plate so as to face the cold cathode fluorescent tube. It has been said that it is possible to prevent luminance unevenness from occurring in the planar light.
JP-A-2005-347062

  However, in the conventional illumination device as described above, it is necessary to form a printed film on the surface of the diffusion plate so as to match the location where the cold cathode fluorescent tube (light source) is installed. For this reason, in the conventional illuminating device, time and an effort were required for formation of a printing film, and there existed a problem that the cost of a diffusion plate and an illuminating device occurred. Further, in this conventional illumination device, it is necessary to assemble the diffusion plate with high accuracy so that the printed film and the cold cathode fluorescent tube face each other. If the positions of the printed film and the cold cathode fluorescent tube are shifted, the printing is performed. The effect of preventing luminance unevenness due to the film is remarkably lowered, and the light emission quality of the lighting device may be remarkably lowered.

  In view of the above problems, an object of the present invention is to provide a lighting device that is excellent in light emission quality and low in cost, a manufacturing method thereof, and a display device using the lighting device.

In order to achieve the above object, an illumination device according to the present invention includes a light source and a diffusion plate that diffuses light from the light source,
On the light source side surface of the diffusion plate, a convex portion and a concave portion are provided,
The diffusing plate is characterized in that a reflecting portion that reflects light from the light source is formed in the convex portion or the concave portion.

  In the illuminating device configured as described above, a reflective portion that reflects light from the light source is formed on the convex portion or concave portion provided on the light source side surface of the diffusion plate. Thereby, it is possible to prevent the image of the light source from appearing on the surface of the diffusion plate, and it is possible to prevent luminance unevenness from occurring in the light emitted from the diffusion plate to the outside. As a result, unlike the conventional example, it is possible to configure a low-cost lighting device having excellent light emission quality.

  In the illumination device, it is preferable that the reflecting portion is made of a paint having a predetermined color and having a high light reflectance applied to the convex portion or the concave portion.

  In this case, an illumination device having a simple structure and excellent light emission quality can be easily configured.

  In addition, the display device of the present invention is characterized by using any one of the above illumination devices.

  In the display device configured as described above, a low-cost lighting device with excellent light emission quality is used, so that a low-cost and high-performance display device can be easily configured.

Moreover, the manufacturing method of the illuminating device of this invention is a manufacturing method of the illuminating device provided with the light source and the diffusion plate which diffuses the light from the said light source,
A step of forming a reflecting portion that reflects light from the light source on the convex portion or the concave portion using a transfer method on the surface of the diffuser plate having the convex portion and the concave portion; To do.

  In the manufacturing method of the lighting device configured as described above, in the forming step, the light from the light source is reflected on the convex portion or the concave portion by using the transfer method with respect to the surface having the convex portion and the concave portion of the diffusion plate. A reflection part is formed. Thereby, it is possible to prevent the image of the light source from appearing on the surface of the diffusion plate, and it is possible to prevent luminance unevenness from occurring in the light emitted from the diffusion plate to the outside. As a result, unlike the conventional example, it is possible to configure a low-cost lighting device having excellent light emission quality.

  Moreover, in the manufacturing method of the said illuminating device, you may form the said reflection part only in the said convex part using a roller at the said formation process.

  In this case, the formation process can be performed more easily, and a low-cost illumination device having excellent light emission quality can be easily configured.

  Moreover, in the manufacturing method of the said illuminating device, it is preferable that the said reflection part is comprised with the coating material of the predetermined color with a high light reflectance.

  In this case, an illumination device having a simple structure and excellent light emission quality can be easily configured.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the cheap illuminating device which was excellent in the light emission quality, its manufacturing method, and the display apparatus using the illuminating device.

  Hereinafter, preferred embodiments showing a lighting device, a manufacturing method thereof, and a display device of the present invention will be described with reference to the drawings. In the following description, the case where the present invention is applied to a transmissive liquid crystal display device will be described as an example. Moreover, the dimension of the structural member in each figure does not faithfully represent the actual dimension of the structural member, the dimensional ratio of each structural member, or the like.

  FIG. 1 is a schematic cross-sectional view illustrating an illumination device and a liquid crystal display device according to an embodiment of the present invention. In the figure, the liquid crystal display device 1 according to the present embodiment includes a liquid crystal panel 2 as a display unit installed on the upper side of the figure as a viewing side (display side), and a non-display side of the liquid crystal panel 2 (lower side of the figure). And an illumination device 3 of the present invention that generates illumination light for illuminating the liquid crystal panel 2.

  The liquid crystal panel 2 includes a liquid crystal layer 4, an active matrix substrate 5 and a color filter substrate 6 as a pair of transparent substrates sandwiching the liquid crystal layer 4, and active matrix substrate 5 and color filter substrate 6 on respective outer surfaces. Provided polarizing plates 7 and 8 are provided. Further, the liquid crystal panel 2 is provided with a driver device 9 for driving the liquid crystal panel 2 and a drive circuit device 10 connected to the driver device 9 via the flexible printed circuit board 11. The liquid crystal layer 4 can be driven pixel by pixel. In the liquid crystal panel 2, the polarization state of the illumination light incident through the polarizing plate 7 is modulated by the liquid crystal layer 4 and the amount of light passing through the polarizing plate 8 is controlled, so that a desired image is displayed. Is done.

  Note that the liquid crystal mode and the pixel structure of the liquid crystal panel 2 are arbitrary. Moreover, the drive mode of the liquid crystal panel 2 is also arbitrary. That is, as the liquid crystal panel 2, any liquid crystal panel that can display information can be used. Therefore, the detailed structure of the liquid crystal panel 2 is not shown in FIG.

  The illuminating device 3 is provided with a bottomed chassis 12 opened on the upper side (liquid crystal panel 2 side) in the figure, and a frame-like frame 13 installed on the liquid crystal panel 2 side of the chassis 12. The chassis 12 and the frame 13 are made of metal or synthetic resin and are sandwiched by a bezel 14 having an L-shaped cross section in a state where the liquid crystal panel 2 is installed above the frame 13. Thereby, the illuminating device 3 is assembled to the liquid crystal panel 2 and integrated as a transmissive liquid crystal display device 1 in which illumination light from the illuminating device 3 enters the liquid crystal panel 2.

  The illumination device 3 is provided on the inner surface of the chassis 12, the diffusion plate 15 installed so as to cover the opening of the chassis 12, the optical sheet 17 installed on the liquid crystal panel 2 side above the diffusion plate 15. And a reflective sheet 19. In the lighting device 3, a plurality of, for example, six cold cathode fluorescent tubes 20 are provided inside the chassis 12 on the lower side of the liquid crystal panel 2 to constitute a direct-type lighting device 3. And in the illuminating device 3, the light from each cold cathode fluorescent tube 20 is radiate | emitted as the said illumination light from the light emission surface of the illuminating device 3 arrange | positioned facing the liquid crystal panel 2. FIG.

  In addition to the above description, instead of the cold cathode fluorescent tube 20, a hot cathode fluorescent tube, an LED, or the like can be used as a light source.

  The diffusion plate 15 is made of a synthetic resin such as a rectangular polystyrene resin or polycarbonate resin having a thickness of about 2 mm, for example, and diffuses the light from the cold cathode fluorescent tube 20 and emits the light toward the optical sheet 17 side. To do. The diffusion plate 15 is mounted on a frame-like surface provided on the upper side of the chassis 12 on the four sides, and the surface of the chassis 12 and the surface of the frame 13 are interposed with an elastically deformable pressing member 16 interposed therebetween. It is incorporated in the lighting device 3 in a state of being held between the inner surface and the inner surface. Further, the diffusion plate 15 is supported at its substantially central portion by a transparent support member (not shown) installed inside the chassis 12, and is prevented from bending inside the chassis 12.

  Further, the diffusion plate 15 is movably held between the chassis 12 and the pressing member 16, and the diffusion plate is affected by heat such as heat generation of the cold cathode fluorescent tube 20 and temperature rise inside the chassis 12. 15, even when expansion (plastic) deformation occurs, the pressing member 16 is elastically deformed so that the plastic deformation is absorbed and the diffusibility of light from the cold cathode fluorescent tube 20 is not reduced as much as possible. Yes.

  Further, as will be described in detail later, the diffuser plate 15 is provided with a reflecting portion that reflects light from the cold cathode fluorescent tube 20 on the surface on the cold cathode fluorescent tube (light source) 20 side, and uneven brightness is provided. Can be prevented from occurring in the illumination light as much as possible.

The optical sheet 17 includes a light collecting sheet made of, for example, a synthetic resin film having a thickness of about 0.5 mm, and is configured to increase the luminance of the illumination light to the liquid crystal panel 2. The optical sheet 17 is appropriately laminated with known optical sheet materials such as a prism sheet, a diffusion sheet, and a polarizing sheet for improving the display quality on the display surface of the liquid crystal panel 2 as necessary. It has become. The optical sheet 17 converts the light emitted from the diffusion plate 15 into planar light having a predetermined luminance (for example, 10000 cd / m ² ) or more and uniform luminance, and is used as illumination light for the liquid crystal panel 2. It is comprised so that it may inject into the side. In addition to the above description, for example, an optical member such as a diffusion sheet for adjusting the viewing angle of the liquid crystal panel 2 may be appropriately stacked above the liquid crystal panel 2 (display surface side).

  Further, in the optical sheet 17, for example, a protruding portion that protrudes to the left in FIG. 1 is formed in the central portion on the left end side in FIG. 1 that is on the upper side when the liquid crystal display device 1 is actually used. In the optical sheet 17, only the protruding portion is sandwiched between the inner surface of the frame 13 and the pressing member 16 with the elastic material 18 interposed therebetween. The optical sheet 17 can be expanded and contracted inside the lighting device 3. Built in state. Thereby, in the optical sheet 17, even when expansion / contraction (plastic) deformation occurs due to the influence of the heat such as the heat generation of the cold cathode fluorescent tube 20, free expansion / contraction deformation based on the protruding portion becomes possible. The optical sheet 17 is configured to prevent wrinkles and deflections from occurring as much as possible. As a result, in the liquid crystal display device 1, it is possible to prevent the display quality of the liquid crystal panel 2 from being deteriorated as much as possible due to the bending of the optical sheet 17 or the like on the display surface of the liquid crystal panel 2.

  Each cold cathode fluorescent tube 20 has a straight tube shape, and electrode portions (not shown) provided at both ends thereof are supported outside the chassis 12. Each of the cold cathode fluorescent tubes 20 is a thin tube having a diameter of about 3.0 to 4.0 mm and excellent in luminous efficiency. Each cold cathode fluorescent tube 20 is a light source holder (not shown). Thus, the distance between each of the diffusion plate 15 and the reflection sheet 19 is held in the chassis 12 in a state where the distance is maintained at a predetermined distance. Further, the cold cathode fluorescent tube 20 is arranged so that its longitudinal direction is parallel to a direction orthogonal to the direction of gravity action. As a result, in the cold cathode fluorescent tube 20, mercury (vapor) enclosed therein is prevented from gathering on one end side in the longitudinal direction due to the action of gravity, and the lamp life is greatly improved. Yes.

  The reflection sheet 19 is made of a metal thin film having a high light reflectance such as aluminum or silver having a thickness of about 0.2 to 0.5 mm, for example, and reflects the light from the cold cathode fluorescent tube 20 toward the diffusion plate 15. To function as a reflector. Thereby, in the illuminating device 3, the light emitted from the cold cathode fluorescent tube 20 can be efficiently reflected to the diffusion plate 15 side, and the use efficiency of the light and the luminance at the diffusion plate 15 can be increased. In addition to this description, a reflective sheet material made of synthetic resin is used in place of the metal thin film, or the inner surface of the chassis 12 is reflected by applying a paint having a high light reflectance such as white. It can also function as a plate.

  Here, the diffusion plate 15 will be specifically described with reference to FIGS.

  FIG. 2 is a side view showing the configuration of the main part of the diffusion plate shown in FIG. 1, and FIG. 3 is a plan view showing the surface of the diffusion plate when viewed from the cold cathode fluorescent tube side shown in FIG.

  2 and 3, the diffusing plate 15 is disposed on the liquid crystal panel 2 side, and has a light emitting surface 15a for emitting the planar illumination light and a surface 15b disposed on the cold cathode fluorescent tube (light source) 20 side. I have. In addition, in the diffusing plate 15, as described above, the reflecting portion 21 that reflects light from the cold cathode fluorescent tube 20 is formed on the surface 15 b on the cold cathode fluorescent tube (light source) 20 side.

  Specifically, as illustrated in FIG. 2, the surface 15b of the diffusing plate 15 is configured to have a convex / concave shape having convex portions 15b1 and concave portions 15b2. This uneven shape is inherently provided by the polystyrene resin or polycarbonate resin constituting the diffusion plate 15, and the unevenness of the uneven shape is very small, for example, about 50 to 100 microns. And in the diffusing plate 15, the reflection part 21 is formed in the convex part 15b1.

  The reflecting portion 21 is made of a paint of a predetermined color (for example, white or silver) having a high light reflectance, and is provided on the convex portion 15b1 by a transfer method using a roller (details will be described later). . Moreover, the reflective part 21 is randomly formed on the surface 15b according to the irregular shape of the surface 15b provided irregularly as illustrated by a circle in FIG. And the reflection part 21 reflects the light from the cold cathode fluorescent tube 20 to the reflection sheet 19 side. Thereby, the optical path of the light from the cold cathode fluorescent tube 20 is lengthened inside the space between the chassis 12 and the diffusion plate 15. As a result, the luminance at the portion directly above the cold cathode fluorescent tube 20 on the light emitting surface 15a can be appropriately reduced, and the occurrence of luminance unevenness in the illumination light emitted from the light emitting surface 15a can be prevented as much as possible.

  In addition, about the light emission surface 15a, in FIG. 2, illustration of the convex part and recessed part at the side of the light emission surface 15a is abbreviate | omitted for the simplification of the drawing (the same is true of FIG. 4 described later).

  Hereinafter, with reference to FIG. 4, the manufacturing method of the illuminating device 3 comprised as mentioned above is demonstrated concretely. In the following description, a forming process for forming the reflecting portion 21 on the surface 15b of the diffusion plate 15 will be described.

  FIG. 4A to FIG. 4C are diagrams for explaining a process of forming the reflecting portion shown in FIG.

  As shown in FIG. 4A, the diffusion plate 15 is first installed on a work table (not shown) in contact with the light emitting surface 15a so that the surface 15b is disposed on the upper side. Note that the dimension indicated by “H” in FIG. 4A is the height difference (about 50 to 100 microns) of the uneven shape, and is the dimension from the top of the protrusion 15b1 to the bottom of the recess 15b2.

  Next, as shown in FIG. 4B, the roller R coated with the paint of the predetermined color is rolled on the surface 15b of the diffusion plate 15 in the direction of the arrow r in the figure to transfer the paint. As a result, as shown in FIG. 4C, the reflecting portion 21 is formed only on the convex portion 15b1 out of the convex portion 15b1 and the concave portion 15b2.

  In the illumination device 3 of the present embodiment configured as described above, the projection 15b1 provided on the surface 15b of the diffusion plate 15 on the cold cathode fluorescent tube (light source) 20 side is from the cold cathode fluorescent tube 20. A reflecting portion 21 that reflects light is formed. Thereby, in the illuminating device 3 of this embodiment, it can prevent that the image (lamp image) of the cold cathode fluorescent tube 20 appears on the light emission surface 15a of the diffusion plate 15, and is radiate | emitted outside from the said diffusion plate 15. FIG. It is possible to prevent luminance unevenness from occurring in the light. As a result, in the present embodiment, unlike the conventional example, it is possible to configure the illumination device 3 that is excellent in light emission quality and low in cost.

  Further, in the liquid crystal display device 1 of the present embodiment, the low-cost illumination device 3 having excellent light emission quality is used, so that the low-cost and high-performance liquid crystal display device 1 can be easily configured.

  The above embodiments are all illustrative and not restrictive. The technical scope of the present invention is defined by the claims, and all modifications within the scope equivalent to the configurations described therein are also included in the technical scope of the present invention.

  For example, in the above description, the case where the present invention is applied to a transmissive liquid crystal display device has been described. However, the lighting device of the present invention is not limited to this, and the image, The present invention can be applied to various display devices including a non-light emitting display unit that displays information such as characters. Specifically, the illumination device of the present invention can be suitably used for a transflective liquid crystal display device or a projection display device using a liquid crystal panel as a light valve.

  Further, in the above description, the case where the reflecting portion is provided on the convex portion provided on the surface of the diffusion plate has been described, but the present invention is not limited to this, and the convex portion provided on the surface of the diffusion plate is provided. What is necessary is just to form a reflection part with respect to one of a part or a recessed part. Specifically, for example, after providing a reflective portion over the entire surface of the diffusion plate, using a mask member or the like, only the reflective portion formed on the convex portion is removed and the reflective portion is formed only on the concave portion May be. Moreover, you may form a reflection part in a convex part or a recessed part using a screen printing method.

  However, as in the above-described embodiment, in the formation process, when the reflective part is formed only on the convex part using a roller, the formation process can be performed more easily, and the cost is excellent in light emission quality. This is preferable in that an inexpensive lighting device can be easily configured.

  Further, in the above description, the case where the reflecting portion is made of a paint of a predetermined color having a high light reflectance has been described. However, the reflecting portion of the present invention is not limited to this, and the light from the light source is used. Anything that can be reflected is acceptable. Specifically, a bead material having a refractive index different from the refractive index of the diffusion plate, metal fine particles such as alumina, and the like can be used for the reflecting portion.

  However, as in the above-described embodiment, it is preferable that the reflecting portion is formed of a predetermined color paint having a high light reflectance in that a lighting device having a simple structure and excellent light emission quality can be easily formed. .

  Further, in the above description, the case where the reflection portion is formed with respect to the convex portion naturally provided on the surface of the diffusion plate has been described, but the present invention is not limited to this, for example, the diffusion plate A configuration in which the surface is made uneven by embossing the surface or the like, and a reflective portion is provided in the convex portion or the concave portion may be employed.

  In addition to the above description, for example, by using a prism-shaped diffuser plate in which convex portions and concave portions are regularly formed on the light source side surface, a reflective portion is formed on the regular convex portions or concave portions. You can also.

  INDUSTRIAL APPLICABILITY The present invention is useful for a lighting device with excellent light emission quality and a low cost, a manufacturing method thereof, and a display device using the lighting device.

It is a schematic sectional drawing explaining the illuminating device and liquid crystal display device concerning one Embodiment of this invention. It is a side view which shows the principal part structure of the diffusion plate shown in FIG. It is a top view which shows the surface of the said diffusion plate when it sees from the cold cathode fluorescent tube side shown in FIG. (A)-(c) is a figure explaining the formation process of the reflection part shown in FIG.

Explanation of symbols

1 Liquid crystal display device (display device)
3 Illuminating device 15 Diffuser 15b Surface (on light source side) 15b1 Convex part 15b2 Concave part 20 Cold cathode fluorescent tube (light source)
21 Reflector R Roller

Claims (6)

A lighting device comprising a light source and a diffusion plate for diffusing light from the light source,
On the light source side surface of the diffusion plate, a convex portion and a concave portion are provided,
In the diffusing plate, a reflective part that reflects light from the light source is formed in the convex part or the concave part.
A lighting device characterized by that. The illuminating device according to claim 1, wherein the reflecting portion is made of a paint having a predetermined color and having a high light reflectance applied to the convex portion or the concave portion. A display device using the illumination device according to claim 1. A method of manufacturing a lighting device including a light source and a diffusion plate that diffuses light from the light source,
A forming step of forming a reflecting portion that reflects light from the light source on the convex portion or the concave portion using a transfer method on the surface having the convex portion and the concave portion of the diffusion plate,
The manufacturing method of the illuminating device characterized by comprising. The manufacturing method of the illuminating device according to claim 4, wherein in the forming step, the reflective portion is formed only on the convex portion using a roller. The method of manufacturing an illumination device according to claim 4, wherein the reflection portion is made of a paint of a predetermined color having a high light reflectance.

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