JP2008159452A - Backlight device, and display device having it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight device that is structured to reflect light emitted from a positioning projecting part 26 on the inside surface of a recessed part 27 and thereby prevent generation of a bright point by emitting the light toward a liquid crystal display panel 35, in a backlight device that is structured to receive the positioning projecting part 26 at a side end of a light guide plate 10 into a recessed part 27 formed on the inside surface of a frame body 15 to position it. <P>SOLUTION: A step 28 is formed at a position of the recessed part 27 of the frame body 15 corresponding to the upper edge of the positioning projecting part 26 of the light guide plate 10; an extension part extended to sides of prism sheets 21 and 22 constituting an optical sheet 20 or ears 31, 32 and 33 of a diffusion sheet 23 are received by the part of the step 28; and generation of a bright point is prevented by blocking, by such an extension part, light emitted from the positioning projecting part 26 and reflected on the inside surface of the recessed part 27. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a backlight device and a display device having the backlight device, and more particularly to a backlight device using a light guide plate and a display device in which illumination is performed from the back side by such a backlight device.

  Liquid crystal display devices are widely used as display devices of various sizes. In the liquid crystal display device, light incident from the back side is displayed by controlling transmission and blocking of light of a liquid crystal portion corresponding to each pixel according to a signal. Here, in particular, since the liquid crystal display device cannot emit light by itself, a backlight device is provided on the back side, and light is incident from the back side by such a backlight device.

  For example, as disclosed in Japanese Patent Application Laid-Open Nos. 2001-166116 and 2001-215505, the backlight device is composed of a light guide plate, and a light source located at the side end of the light guide plate. Light is incident on the light guide plate, and the light incident on the bottom surface side of the light guide plate is reflected and guided to the main surface side, thereby illuminating the liquid crystal display device as a surface light source from the back side.

  As shown in FIGS. 1 and 2, for example, a conventional backlight device of a liquid crystal display device includes a light guide plate 10, and a light source 11 composed of LEDs arranged on the side ends of the light guide plate 10 includes a light guide plate 10. The light is made to enter. The LED 11 is supplied with power by the power supply flexible substrate 12 and emits light. The light guide plate 10 is accommodated in a rectangular frame 15, the bottom side portion of the frame 15 is closed by the reflecting plate 16, and the light emitted to the bottom side of the light guide plate 10 is reflected. Then, it is made to enter the light guide plate 10 again.

  An optical sheet 20 is disposed on the main surface of the light guide plate 10 and on the light exit surface. The optical sheet 20 is composed of prism sheets 21 and 22 and a diffusion sheet 23, for example.

  Here, in particular, the light guide plate 10 is provided with positioning projections 26 on the side surfaces thereof facing each other in order to perform positioning with respect to the frame body 15, and such positioning projections 26 are provided on the frame body 15. It is made to receive in the recessed part 27 currently formed in the inner peripheral part. The three sheets 21 to 23 constituting the optical sheet 20 are also formed with ears 31, 32 and 33, respectively, and these ears 31, 32 and 33 are received in the recesses 27 of the frame body 15. .

  As described above, the backlight of the liquid crystal display device uses the light guide plate 10 in order to use the light from the light source 11 as a surface light source, and includes a frame 15 made of resin or the like as a structure around the light guide plate 10. Further, in order to improve luminance, a material having a high reflectance is often used for the frame 15. Therefore, light emitted from the positioning projection 26 of the light guide plate 10 is easily reflected on the inner peripheral surface of the frame 15.

  That is, as shown in FIG. 2 and FIG. 3, the light guide plate 10 is provided with a positioning protrusion 26 so as to protrude to the side end for positioning with the frame body 15. Here, the positioning protrusion 26 is also made of a material that is continuous with the light guide plate 10 and forms a part of the light guide plate 10. Then, light incident through the light source 11 may propagate inside the light guide plate 10 and exit to the outside. When such light hits the inner peripheral surface of the frame body 15 that fits with the light guide plate 10, it becomes a bright spot. (See FIGS. 3 and 4).

In order to eliminate the bright spots caused by the light emitted from the positioning projections 26 of the light guide plate 10 and reflected by the inner peripheral surface of the concave portion 27 of the light guide plate 10, conventionally, for example, as shown in FIG. The exit portion of the concave portion 27 is eliminated by attaching a light blocking material such as a light blocking tape 38. However, such a measure for eliminating the bright spot by the light shielding tape 38 increases the number of parts and the number of processes. For this reason, the cost of the liquid crystal display device is increased. Therefore, as another solution, the positioning projection 26 of the light guide plate 10 is formed at a position far from the display area of the liquid crystal display device, thereby preventing the light emitted from the projection 26 from reaching the display area. It is possible. However, if such measures are taken, the positioning projection 26 must be largely separated from the display area on the outer peripheral side, so that the outer shape of the backlight device becomes large, particularly for use as a small display device. Becomes inappropriate.
JP 2001-166116 A JP 2001-215505 A

  An object of the present invention is to provide a backlight device that eliminates a bright spot caused by light emitted from a positioning projection of a light guide plate and reflected by an inner peripheral portion of a concave portion of a frame, thereby improving display quality. And a display device using the backlight device.

  Another object of the present invention is to reduce the bright spots generated by reflecting the light emitted from the positioning projections at the inner peripheral part of the recesses of the frame without using a separate part such as a light shielding tape. A backlight device and a display device using such a backlight device are provided.

  Still another object of the present invention is to provide a backlight device capable of improving the bright spot without increasing the cost, and a liquid crystal display device using such a backlight device.

  The above-described problems and other problems of the present application will be made clear by the technical idea of the present invention and the embodiments thereof described below.

The main invention of the present application is a light guide plate that emits light from a light source at a side edge from a main surface;
A frame for receiving the light guide plate;
An optical sheet disposed on the main surface of the light guide plate from which light is emitted;
In a backlight device having
A positioning projection is provided at a side end of the light guide plate, and the positioning projection is received in a recess formed in an inner peripheral portion of the frame body,
A step is formed at a portion of the recess having a height substantially the same as the main surface of the light guide plate, and the step expands the recess in the width direction or the protrusion direction of the protrusion, and the protrusion of the light guide plate Positioning ears are provided on the optical sheet at corresponding positions, and the ears are extended from the protrusions in the width direction or the protruding direction of the protrusions and are received in the steps. It is about.

  Here, the step of the concave portion of the frame body is larger than the protrusion in the width direction of the protrusion, and the extension in the width direction of the protrusion of the ear of the optical sheet is received in the step. You may make it close | close the clearance gap between a protrusion and the said recessed part. The optical sheet may include a prism sheet, and an extension portion of the prism sheet may be received in the step. The optical sheet may include a diffusion sheet, and an extension portion of the diffusion sheet may be received in the step. The optical sheet may include a prism sheet and a diffusion sheet, and an extension portion of the prism sheet and the ear of the diffusion sheet may be received in the step.

A main invention related to a display device is a display device having a display panel and a backlight device that illuminates the display panel from the back side.
A light guide plate that emits light from a light source at a side edge of the backlight device from a main surface; a frame that receives the light guide plate; and an optical sheet that is disposed on the main surface of the light guide plate from which light is emitted. Have
A positioning projection is provided at a side end of the light guide plate, and the positioning projection is received in a recess formed in an inner peripheral portion of the frame body,
A step is formed at a portion of the recess having a height substantially the same as the main surface of the light guide plate, and the step expands the recess in the width direction or the protrusion direction of the protrusion, and the protrusion of the light guide plate The present invention relates to a display device characterized in that a positioning ear is provided on the optical sheet at a corresponding position, the ear is extended from the projection in the width direction or the projection direction of the projection, and is received by the step. Is.

  Here, the display panel may be a liquid crystal display panel. The liquid crystal display panel may be held by a frame of the backlight device.

  In a preferred aspect of the present invention, the bright spot due to the reflected light from the resin frame of the backlight device of the liquid crystal display device is reduced, and the image quality is improved. That is, in order to fit the backlight and the frame made of resin, a positioning projection is provided on the light guide plate and fixed to the frame, and the light emitted from the positioning projection is applied to the frame. In order to prevent reflection and becoming a bright spot, a step is provided in the concave portion of the frame body that receives the positioning protrusion of the light guide plate, and a part of the optical sheet that is an extension of the ear is received on the step. Thus, it extends over the side end of the positioning projection and covers the portion that is reflected and generates a bright spot. According to such a configuration, it is possible to block the light that is emitted from the positioning projection and becomes the bright spot without adding a light shielding tape, a light shielding sheet, or other parts that block the reflected light that becomes the bright spot. Therefore, it will lead to cost reduction. And since the bright spot of a liquid crystal display device can be improved, image quality is improved. Further, since bright spots can be eliminated without using another part such as a light shielding sheet, the cost of the backlight device can be reduced.

  The main invention of the present application is a light guide plate that emits light from a light source at a side edge from a main surface, a frame that receives the light guide plate, and an optical sheet that is disposed on the main surface of the light guide plate from which light is emitted. , A positioning projection is provided at a side end of the light guide plate, the positioning projection is received in a recess formed in the inner peripheral portion of the frame body, and the main portion of the light guide plate in the recess is A step is formed at a portion having the same height as the surface, and the recess expands in the width direction or the protruding direction of the protrusion by the step, and the ear for positioning the optical sheet at a position corresponding to the protrusion of the light guide plate. The ear is extended in the width direction or the protruding direction of the protruding portion from the protruding portion and is received in the step.

  Therefore, according to such a backlight device, light emitted from the light guide plate through the side end of the positioning projection of the light guide plate and reflected by the inner peripheral surface of the recess of the frame is formed in the recess. Since it is blocked by the optical sheet received in the step, no light is emitted to the outside and no bright spot is generated, thereby improving the image quality. In addition, since it is not necessary to use a separate member such as a light shielding sheet, the structure of the backlight device is simplified, and the backlight device can be configured with a small number of parts. This makes it possible to reduce the cost of the backlight device.

  A main invention related to a display device is a display device having a display panel and a backlight device that illuminates the display panel from the back side. The backlight device guides light from a light source at a side edge from the main surface. A light guide, a frame that receives the light guide plate, and an optical sheet that is disposed on a main surface of the light guide plate from which light is emitted, and a positioning protrusion is provided at a side end of the light guide plate. The protrusion is received in a recess formed in the inner peripheral portion of the frame body, and a step is formed at a portion substantially the same height as the main surface of the light guide plate of the recess, and the recess forms the recess in the width direction of the protrusion. Alternatively, the optical sheet is provided with positioning ears that are enlarged in the projecting direction and correspond to the projecting portions of the light guide plate, and the ears are extended from the projecting portions in the width direction or projecting direction of the projecting portions. It is intended to be accepted

  Therefore, according to such a display device, the light emitted from the positioning projection of the light guide plate of the backlight device and reflected by the inner peripheral surface of the recess of the frame is received in the step provided in the recess. Therefore, the light constituting such a bright spot does not enter the liquid crystal display device, thereby preventing the liquid crystal display device from partially shining and degrading the image quality. And high-quality display operation can be achieved.

  The present invention will be described below with reference to embodiments shown in the drawings. FIG. 6 shows the overall configuration of a liquid crystal display device including the backlight device of the present embodiment, and this liquid crystal display device includes a flat plate-shaped light guide plate 10 made of a transparent resin. On the side end side of the light guide plate 10, a light source 11 made of LEDs is disposed. The LED 11 is supplied with power via the power supply flexible substrate 12, thereby emitting light, and causing light to enter the light guide plate 10 from its side end. Such a light guide plate 10 is accommodated in a rectangular frame 15. Here, the bottom opening of the frame 15 is closed by the reflector 16. Such a reflection plate 16 reflects the light emitted from the bottom of the light guide plate 10 and guides it again into the light guide plate 10, thereby improving the light utilization efficiency.

  Three optical sheets 20 are disposed on the light guide plate 10. These optical sheets 20 are composed of, for example, prism sheets 21 and 22 and a diffusion sheet 23.

  Next, positioning of the light guide plate 10 and the optical sheet 20 with respect to the frame 15 will be described with reference to FIGS. A positioning protrusion 26 is formed on the outer periphery of the light guide plate 10 so as to protrude laterally. Such a positioning projection 26 is received in a recess 27 formed on the inner peripheral surface of the frame 15. The state in which the positioning projection 26 is received by the recess 27 is as shown in FIGS. In the recess 27 of the frame 15 that receives the positioning projection 26, a step 28 is formed at a position substantially opposite to the upper edge of the positioning projection 26 of the light guide plate 10. In particular, the prism sheets 21 and 22 constituting the sheet 20 or the ears 31, 32 and 33 of the diffusion sheet 23 are extended in the lateral direction. That is, by providing such a step 28, the dimensions of the ears 31, 32 of the prism sheets 21, 22 or the ears 33 of the diffusion sheet 23 in the width direction of the positioning projection 26 can be made larger than those of the recess 27. The light serving as the bright spot can be blocked by the ears 31, 32, 33 of the prism sheets 21, 22 or the diffusion sheet 23 received in the step 28.

  Since the positioning protrusions 26 are integrally connected to the side end of the light guide plate 10 and are continuously formed of the same transparent resin material, the positioning protrusions 26 are also formed of the light guide plate 10. Part of. Therefore, the light from the light source 11 is transmitted through the light guide plate 10 and the positioning projection 26 and is emitted from the side end of the positioning projection 26. As shown in FIGS. 9 to 11, such light is reflected by the inner peripheral surface of the concave portion 27 of the frame body 15 and tends to be emitted upward. However, light is shielded or diffused by the portions of the ears 31, 32, 33 of the prism sheets 21, 22 or the diffusion sheet 23 extended laterally by the step 28. Therefore, the light emitted from the positioning projection 26 and reflected by the inner peripheral surface of the recess 27 does not exit upward, thereby suppressing the occurrence of bright spots. Therefore, the light emitted from the positioning projection 26 is not incident on the liquid crystal display panel 35 attached to the attachment portion 36 at the upper portion of the frame 15 shown in FIG. The problem of shining partially bright by the points is prevented.

  The backlight device is provided with an optical sheet 20 composed of prism sheets 21 and 22 and a diffusion sheet 23 for improving the normal luminance. By providing the optical sheets 21, 22, 23 with the ears 31, 32, 33 similar to the light guide plate 10, and providing the step 28 in the recess 27 of the frame 15, The light emitted between the positioning projections 26 and the recesses 27 of the light guide plate 10 is stopped at the side edge portions of the prism sheets 21 and 22 and the ears 31, 32 and 33 of the diffusion sheet 23, thereby performing a light shielding operation. I am doing so. In general, the prism sheets 21 and 22 and the diffusion sheet 23 weaken the bright spot of the light emitted from the positioning projection 26, and the prism sheets 21 and 22 and the diffusion sheet 23 change the direction of the light to the liquid crystal display panel 35. It has the effect of preventing light from reaching. Accordingly, it is effective to extend one of the prism sheets 21 and 22 or the diffusion sheet 23 laterally, and the plurality of optical sheets of these sheets 21, 22, and 23 are side by side. By extending to the end side, a combined effect can be expected. In any case, the bright spot of the liquid crystal display device is improved, thereby improving the image quality of the liquid crystal display panel 35. Further, since bright spots can be eliminated without using additional parts such as the conventional light shielding tape 38 (see FIG. 5), the cost of the backlight device can be reduced.

  Next, a combination of a plurality of optical sheets 21, 22, and 23 will be described with reference to FIGS. In these drawings, the portion A shows a cross section (A to A ′ cross section) in the center in the width direction of the positioning projection 26 in FIG. 8B, and the portion B is the side of the positioning projection 26 in FIG. 8B. The cross section (BB cross section) of the part of the end side is shown.

  FIG. 12 shows a configuration in which only the ear 33 of the diffusion sheet 23 on the lowermost side is extended to the side of the step 28. FIG. 13 shows a state in which the ear 31 of the uppermost prism sheet 21 is extended to the upper part of the step 28 of the recess 27. On the other hand, FIG. 14 shows a form in which the ear 32 of the intermediate prism sheet 22 is extended to the level difference 28 of the recess 27.

  FIG. 15 shows a configuration in which the ears 32 and 33 of the prism sheet 22 and the diffusion sheet 23 are respectively extended to the step 28 of the recess 27. FIG. 16 shows a state in which the ears 31 and 33 of the prism sheet 21 and the diffusion sheet 23 are extended to the step 28 of the recess 27. FIG. 17 shows a state in which the ears 31 and 32 of the prism sheets 21 and 22 are respectively extended to the step 28 of the recess 27. FIG. 18 shows a state in which the ears 31, 32, 33 of the prism sheets 21, 22 and the diffusion sheet 23 are extended laterally.

  Thus, one, two, or three ears 31, 32, 33 of the prism sheets 21, 22 or the diffusion sheet 23 constituting the optical sheet 20 are connected to the step portion 28 of the recess 27 of the frame 15. Thus, the light emitted from the side end of the positioning projection 26 of the light guide plate 10 and reflected from the inner peripheral surface of the recess 27 to be emitted upward can be blocked. The generation of points is suppressed.

  Although the present invention has been described above with reference to the illustrated embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea of the present invention. For example, in the above embodiment, the ears 31, 32, 33 of the prism sheets 21, 22 or the diffusion sheet 23 constituting the optical sheet 20 are extended in the width direction of the positioning projection 26. Instead of or together with such a configuration, the ears 31, 32, 33 may be extended in the protruding direction of the positioning projection 26.

  The present invention can be used for a backlight device of a liquid crystal display device.

It is a longitudinal cross-sectional view of the conventional liquid crystal display device. It is a top view of the backlight apparatus used for the liquid crystal display device. It is a principal part enlarged plan view which shows positioning of the light-guide plate of a backlight apparatus, and generation | occurrence | production of a luminescent spot. FIG. 4 is a sectional view taken along line BB in FIG. 3. It is sectional drawing similar to FIG. 4 which shows the light shielding operation | movement by a light shielding tape. It is a principal part longitudinal cross-sectional view of the liquid crystal display device which concerns on one embodiment of this invention. It is the top view and principal part enlarged plan view of the backlight apparatus of the liquid crystal display device. It is an expansion disassembled perspective view of the positioning part of the light-guide plate of a backlight apparatus. It is an expanded sectional view of the positioning part of a light-guide plate. It is an expanded sectional view showing the prevention operation of a bright spot. It is an expanded sectional view which shows the suppression operation of the bright spot by two prism sheets. It is principal part sectional drawing which shows the light-shielding operation by a diffusion sheet. It is principal part sectional drawing which shows the light-shielding operation | movement by a prism sheet. It is principal part sectional drawing which shows the light-shielding operation | movement by another prism sheet. It is principal part sectional drawing which shows the light-shielding operation | movement by a prism sheet and a diffusion sheet. It is principal part sectional drawing which shows the light-shielding operation | movement by a prism sheet and a diffusion sheet. It is principal part sectional drawing which shows the light-shielding operation | movement by two prism sheets. It is principal part sectional drawing which shows the light-shielding operation | movement by two prism sheets and a diffusion sheet.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Light guide plate, 11 ... LED (light source), 12 ... Flexible board for electric power feeding, 15 ... Frame, 16 ... Reflecting plate, 20 ... Optical sheet, 21, 22 ... Prism sheet, 23 ... Diffusing sheet, 26 ... For positioning Projection, 27 ... recess, 28 ... step, 31-33 ... ear, 35 ... liquid crystal display panel, 36 ... mounting part, 38 ... shading tape

Claims (8)

A light guide plate that emits light from the light source at the side end from the main surface;
A frame for receiving the light guide plate;
An optical sheet disposed on the main surface of the light guide plate from which light is emitted;
In a backlight device having
A positioning projection is provided at a side end of the light guide plate, and the positioning projection is received in a recess formed in an inner peripheral portion of the frame body,
A step is formed at a portion of the recess having a height substantially the same as the main surface of the light guide plate, and the step expands the recess in the width direction or the protrusion direction of the protrusion, and the protrusion of the light guide plate Positioning ears are provided on the optical sheet at corresponding positions, and the ears are extended from the protrusions in the width direction or the protruding direction of the protrusions and are received in the steps. .   The step of the concave portion of the frame body is larger than the protrusion in the width direction of the protrusion, and the extension in the width direction of the protrusion of the ear of the optical sheet is received by the step. The backlight device according to claim 1, wherein a gap between the concave portion and the concave portion is closed.   The backlight device according to claim 1, wherein the optical sheet includes a prism sheet, and an extension portion of an ear of the prism sheet is received in the step.   The backlight device according to claim 1, wherein the optical sheet includes a diffusion sheet, and an extension portion of an ear of the diffusion sheet is received in the step.   The backlight device according to claim 1, wherein the optical sheet includes a prism sheet and a diffusion sheet, and an extension portion of the prism sheet and the diffusion sheet is received in the step. In a display device having a display panel and a backlight device that illuminates the display panel from the back side,
A light guide plate that emits light from a light source at a side edge of the backlight device from a main surface; a frame that receives the light guide plate; and an optical sheet that is disposed on the main surface of the light guide plate from which light is emitted. Have
A positioning projection is provided at a side end of the light guide plate, and the positioning projection is received in a recess formed in an inner peripheral portion of the frame body,
A step is formed at a portion of the recess having a height substantially the same as the main surface of the light guide plate, and the step expands the recess in the width direction or the protrusion direction of the protrusion, and the protrusion of the light guide plate The display device is characterized in that a positioning ear is provided on the optical sheet at a corresponding position, and the ear extends in the width direction or the protruding direction of the protrusion from the protrusion and is received by the step.   The display device according to claim 6, wherein the display panel is a liquid crystal display panel.   The display device according to claim 6, wherein the liquid crystal display panel is held by a frame of the backlight device.

Images