JP3823964B2 - Light guide plate, backlight device, and method of manufacturing light guide plate - Google Patents

Description

  The present invention relates to a light guide plate used for a backlight unit of a liquid crystal display (LCD), and more specifically, a molten material is injected into a mold for injection molding from a predetermined gate position. The present invention relates to a light guide plate, a backlight device including the light guide plate, and a method for manufacturing the light guide plate.

  The backlight unit of a liquid crystal display device is required to be mass-produced with the spread of electronic devices equipped with the liquid crystal display device. The backlight unit is mainly formed by a light source and a light guide plate that guides light emitted from the light source to emit light.

  As the light source, a fluorescent tube, a light emitting diode (LED), or the like is used. In particular, a light emitting diode is often used when the light source is mounted on a miniaturized and thin electronic device.

  The light guide plate has been used by processing an acrylic plate material into a desired shape. However, the light guide plate can be manufactured by injection molding, which can reduce the manufacturing process and enable mass production with stable quality. ing. Injection molding is a technique for manufacturing a cavity-shaped molded product by filling a cavity of an injection mold with a molten material such as a molten acrylic resin.

  In the injection mold, a molten material injection port called a gate for injecting a molten resin to be filled in the cavity is opened. Thus, the quality of the light guide plate manufactured by injection molding depends on the position of the gate which is the molten material injection port.

  Therefore, various light guide plates having different gate positions of injection molds are manufactured. For example, as shown in FIG. 9, a method of manufacturing the light guide plate 100 by providing the gate 104 on the side surface 102 parallel to the light guide direction of the light incident from the light incident surface 101 of the light guide plate 100, FIG. As shown in FIG. 11, a method of manufacturing the light guide plate 200 by providing the gate 204 on the light incident surface 201, and a method of manufacturing by providing the gate 304 on the anti-light incident surface 303 at a position facing the light incident surface 301 as illustrated in FIG. 11. The technique to do is devised and implemented.

JP 2002-292690 A

  However, when the gate 104 is provided on the side surface 102 as shown in FIG. 9, if a molten material is injected into the cavity of the injection mold through the gate 104, a strong pressure is applied in the vicinity of the gate 104. .

  In general, the light reflecting surface of the light guide plate, that is, the surface facing the light emitting surface 105 in FIG. 9, is formed with a prism pattern, a dot pattern, or the like in order to efficiently raise the incident light toward the light emitting surface. Yes. These patterns are formed by transferring the fine irregularities formed in the cavity of the injection mold to the filled molten material.

  When the pressure to the molten material to be filled is strong, the transfer is improved as much. Therefore, in the light guide plate 100 shown in FIG. 9, the transfer near the side surface 102 where the gate 104 is provided is excellent. In other words, the transfer near the side surface 103 at a position facing the side surface 102 is inferior to that near the side surface 102.

  Therefore, in the light guide plate 100, transfer unevenness having different transfer accuracy occurs on the left and right with respect to the light incident surface 101, and the light emitted from the light emitting surface 105 has nonuniform luminance. There is a problem such as.

  As shown in FIG. 10, when the gate 204 is provided on the light incident surface 201, the transfer unevenness as described above does not occur in the formed light guide plate 200, but the gate is formed on the light incident surface 201. Since traces remain, simply cutting the gate 204 will hinder light propagation. Therefore, the light incident surface 201 needs to be mirror-polished after the gate 204 is cut.

  Therefore, in order to manufacture the light guide plate 200, there are problems that the number of processes is increased more than usual, and the time is lost and the cost is increased due to the increase in manufacturing processes.

  Furthermore, as shown in FIG. 11, when the gate 304 is provided on the light incident surface 303, assuming that the light guide plate 300 has a general wedge shape as the light guide plate, the area of the gate 304 into which the molten material is injected. However, in the worst case, there is a problem that the molten resin cannot be injected. In particular, in an electronic device that is reduced in size and thickness, there is a demand for a very thin light guide plate itself. Therefore, in the case of the light guide plate 300 having a wedge shape, since the light incident surface 303 is thinnest, it is not practical to provide the gate 304 on the light incident surface 303.

  Accordingly, the present invention has been devised in order to solve such problems, a light guide plate that eliminates unnecessary manufacturing processes and has no uneven transfer, a backlight device including the light guide plate, and a light guide plate. It aims at providing the manufacturing method of.

In order to achieve the above object, a light guide plate according to the present invention has a light incident surface and is incident from a plurality of light emitting elements arranged in a row at a predetermined interval in the longitudinal direction of the light incident surface. A wedge-shaped light guide plate that guides light to emit light and emits light in a light guide direction, wherein the plurality of light emitting elements are arranged in a longitudinal direction of the light incident surface. When the even number of light guide plates are arranged in a row at predetermined intervals, a gate for injecting a molten material to be filled in the cavity of the injection mold at the time of injection molding of the light guide plate is provided with a length of the light incident surface. Between the two light emitting elements arranged in the vicinity of the center of the direction, the light emitting elements are provided at positions where neither is arranged .

The light guide plate according to the present invention has a light incident surface, and guides light incident from a plurality of light emitting elements arranged in rows at predetermined intervals in the longitudinal direction of the light incident surface. In the light guide plate having a wedge shape in which the thickness in the light guide direction of the light guided is gradually reduced,
When the plurality of light emitting elements are arranged in an odd number in a row at a predetermined interval in the longitudinal direction of the light incident surface, the light emitting plate is filled in the cavity of the injection mold when the light guide plate is injection molded. Which of the light emitting elements between the light emitting element arranged at the center in the longitudinal direction of the light incident surface and the light emitting element arranged adjacent to any one of the light emitting elements is a gate for injecting a molten material. Are also provided at positions where they are not arranged.

Furthermore, the backlight device according to the present invention guides light incident from the light incident surface and emits light from the light exit surface, and the wedge shape has a thickness that gradually decreases in the light guide direction of the guided light. A light guide plate having a shape, a light source having a plurality of light emitting elements arranged in rows at predetermined intervals in the longitudinal direction of the light incident surface of the light guide plate, and a light reflecting surface side of the light guide plate A reflection sheet, a sheet material composed of a diffusion sheet and a prism sheet arranged to overlap the light output surface side of the light guide plate, and the light source, the reflection sheet, and the sheet material are held on the light guide plate. The light guide plate includes a plurality of light emitting elements arranged in a row at a predetermined interval in the longitudinal direction of the light incident surface . In the cavity of the injection mold during injection molding Gate for injecting the molten material to Hama, between the light-emitting elements arranged in the longitudinal center of the light incident surface, and one array of light-emitting elements adjacent to the light emitting element, the light emitting element Are provided at positions where none of them are arranged.

Furthermore, the backlight device according to the present invention guides light incident from the light incident surface and emits light from the light exit surface, and the wedge shape has a thickness that gradually decreases in the light guide direction of the guided light. A light guide plate having a shape, a light source having a plurality of light emitting elements arranged in rows at predetermined intervals in the longitudinal direction of the light incident surface of the light guide plate, and a light reflecting surface side of the light guide plate A reflection sheet, a sheet material composed of a diffusion sheet and a prism sheet arranged to overlap the light output surface side of the light guide plate, and the light source, the reflection sheet, and the sheet material are held on the light guide plate. The light guide plate includes a plurality of light emitting elements arranged in a row at a predetermined interval in the longitudinal direction of the light incident surface . In the cavity of the injection mold during injection molding Gate for injecting the molten material to Hama, between the light-emitting elements arranged in the longitudinal center of the light incident surface, and one array of light-emitting elements adjacent to the light emitting element, the light emitting element Are provided at positions where none of them are arranged.

Furthermore, the method for manufacturing a light guide plate according to the present invention guides light incident from a plurality of light emitting elements having a light incident surface and arranged in a row at a predetermined interval in the longitudinal direction of the light incident surface. In the manufacturing method of the light guide plate having a wedge shape in which the thickness in the light guide direction of the guided light is gradually decreased, the plurality of light emitting elements are arranged in a longitudinal direction of the light incident surface. When an even number is arranged in a row at a predetermined interval, it is provided at a position where neither of the light emitting elements is arranged between two light emitting elements arranged in the vicinity of the center in the longitudinal direction of the light incident surface. The light guide plate is injection-molded by injecting a molten material to be filled into an injection mold from the formed gate.

Furthermore, the method for manufacturing a light guide plate according to the present invention guides light incident from a plurality of light emitting elements having a light incident surface and arranged in a row at a predetermined interval in the longitudinal direction of the light incident surface. In the manufacturing method of the light guide plate having a wedge shape in which the thickness in the light guide direction of the guided light is gradually decreased, the plurality of light emitting elements are arranged in a longitudinal direction of the light incident surface. When an odd number is arranged in a row at a predetermined interval, a light emitting element arranged in the center in the longitudinal direction of the light incident surface, and a light emitting element arranged adjacent to one of the light emitting elements, The light guide plate is injection-molded by injecting a molten material filled in an injection mold from a gate provided at a position where none of the light-emitting elements are arranged.

  In the light guide plate and the light guide plate manufacturing method of the present invention, a gate for injecting a molten resin to be filled in a cavity of an injection mold at the time of injection molding of the light guide plate is used as a plurality of light emitting elements on the light incident surface side. Are also provided at positions where they are not arranged.

  This makes it possible to suppress left and right transfer unevenness with respect to the light incident direction, and eliminates the need to go through a process of cutting and mirror-polishing the gate formation formed by the gate. Since it can be shortened, it can be manufactured at low cost, and mass production can be easily performed.

  In addition, a backlight device including such a light guide plate can be manufactured at a low cost because the manufacturing time can be shortened, and mass production is facilitated.

  Hereinafter, the best mode for carrying out the invention of a light guide plate, a backlight device, and a method of manufacturing a light guide plate according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a light guide plate 10 shown as the best mode for carrying out the present invention. The light guide plate 10 is used in a backlight unit that is a backlight device of a liquid crystal display device. As a material used for the light guide plate 10, a transparent thermoplastic resin such as a methacrylic resin, a styrene resin, or a polycarbonate resin is used in addition to an acrylic resin.

  For example, the light guide plate 10 is injection-molded using a highly transparent acrylic resin or the like as a material. The light guide plate 10 reflects light incident from the light incident surface 11 in multiple directions by the light reflecting surface 12 which is one main surface of the light guide plate 10, and the reflected light is uniform light from the light emitting surface 13. To be emitted. The light reflecting surface 12 is formed with a fine uneven shape, for example, a prism pattern or a dot pattern. The light that is incident and guided into the light guide plate 10 is efficiently raised in the direction of the light emitting surface 13. Such processing is performed. The prism pattern and the dot pattern of the light reflecting surface 12 are formed by an injection mold.

  The light guide plate 10 has a wedge shape so that the thickness in the light guide direction of the light that is incident and guided from the light incident surface 11 gradually decreases. However, the present invention is not limited to such a wedge shape. It can also be applied to a light guide plate having a shape.

  As the light source of the light guide plate 10, a light source unit 20 including light emitting diodes (LEDs) 21a, 21b, 21c, and 21d arranged in a row at predetermined intervals on the substrate 23 shown in FIG. 1 is used. The light emitting directions of the light emitting diodes 21a, 21b, 21c, and 21d are all the same, and the surfaces that emit light are referred to as light emitting surfaces 22a, 22b, 22c, and 22d, respectively. In the following description, the light emitting diodes 21a, 21b, 21c, and 21d are collectively referred to as the light emitting diode 21, and the light emitting surfaces 22a, 22b, 22c, and 22d are also collectively referred to as the light emitting surface 22. The light emitting diode 21 is, for example, a chip type light emitting diode.

  The pitch of the light emitting diodes 21 arranged on the substrate 23 is determined by the size of the light guide plate 10 and the number of light emitting diodes 21 used. For example, the light emitting diodes 21 are arranged on the substrate 23 at a pitch of 14 mm or 6 mm. The present invention is not limited to the pitch at which the light emitting diodes 21 are arranged, and functions effectively regardless of the pitch at which the light emitting diodes 21 are arranged on the substrate 23.

  The light source unit 20 is installed with respect to the light guide plate 10 so that the light emitting surface 22 of the light emitting diode 21 included in the light source unit 20 is in close contact with the light incident surface 11 of the light guide plate 10. For example, a double-sided tape is affixed to a location indicated by “x” on the substrate 23 of the light source unit 20 shown in FIG. 1 and is adhered to a location that does not affect light reflection on the light reflection surface 12 side of the light guide plate 10. Thus, the light source unit 20 can be attached to the light guide plate 10.

  Further, when the light guide plate 10 and the light source unit 20 are housed in the frame of the backlight unit, the light incident surface 11 of the light guide plate 10 and the light emitting surface 22 of the light emitting diode 21 are brought into close contact with each other. Also good.

  In FIG. 1, positions 11a, 11b, 11c, and 11d surrounded by a dotted line on the light reflecting surface 11 of the light guide plate 10 emit light when the light guide plate 10 and the light source unit 20 are attached as described above. The position where the light emitting surface 22 of the diode 21 is in close contact is shown.

  On the light exit surface 11 of the light guide plate 11, a gate is formed between the position 11b and the position 11c in which the resin of the gate portion of the injection mold that is always formed when the light guide plate 11 is injection molded is cured. Object 15 is left behind.

  Since the gate-formed product 15 left on the light guide plate 11 is completely unnecessary, it is generally necessary to cut the injection-molded product from the runner so as not to remain in the molded product. Will be ground.

  Since the gate formation 15 formed on the light incident surface 11 of the light guide plate 10 enters between the light emitting diode 21b and the light emitting diode 21c when the light source unit 20 is attached to the light guide plate 10, the gate formation 15 is completely obstructive. do not become. In addition, since the gate formation 15 does not exist in the direction in which the light emitting diode 21 emits light, there is no possibility that the function of guiding the light incident on the light guide plate 10 to cause surface emission is impaired.

  As explained in the prior art, when the gate position of the injection mold is the light incident surface of the light guide plate to be molded, the gate cutting process for cutting the gate formation formed by the gate After finishing, it was necessary to further perform mirror surface grinding.

  However, in this way, the gate position of the injection mold is determined so that the gate formation 15 is formed at the position where the light emitting diodes 21 are not arranged on the light incident surface 11 of the light guide plate 10. It is only necessary to perform a gate cutting process such as cutting the formed product 15. Furthermore, this gate cut process may not be a precise process that is very close to the light guide plate 10, and is about the thickness of the light emitting diode 21 in the light emitting direction, for example, about 1 mm thick from the light incident surface 11. A process that leaves the gate forming portion 15 is sufficient.

  An injection mold used when injection molding the light guide plate 10 includes a cavity for forming the light guide plate 10 as shown in FIG. 1 and a gate for forming the gate formation 15. As described above, when the light source unit 20 is attached to the injection-molded light guide plate 10, the gate of the injection mold is provided at a position on the light incident surface 11 where the light emitting diodes 21 are not arranged.

  Moreover, it is desirable that the position of the gate provided in the injection mold is the center position of the light incident surface 11 of the light guide plate 10 to be formed so that the molten material filled in the cavity spreads uniformly in the cavity.

  In the example shown in FIG. 1, since the light emitting diodes 21 of the light source unit 20 are an even number, the central position of the light incident surface 11 of the light guide plate 10 is in a state where none of the light emitting diodes 21 is arranged. Therefore, an injection mold is produced so that the gate is between the position 11b where the light emitting diodes 21b and 21c are disposed and the position 11c.

  FIG. 2 shows a case where there are an odd number of light emitting diodes in the light source section. As shown in FIG. 2, in the light source unit 40, three light emitting diodes 41a, 41b, and 41c are arranged on a substrate 43 at a predetermined interval. The positions 31a, 31b, and 31c shown on the light incident surface 31 of the wedge-shaped light guide plate 30 as in the light guide plate 10 are arranged so that the light emitting surfaces 42a, 42b, and 42c of the light emitting diodes 41a, 41b, and 41c are light of the light guide plate 30. When the light-emitting diodes are attached so as to be in close contact with the incident surface 31, the locations where the respective light-emitting diodes are located are shown.

  Since the light emitting diode 41b is disposed at the center of the light incident surface 31, a gate cannot be provided here. Accordingly, the gate of the injection mold has a position where the gate formation 35a or the gate forming portion 35b is formed by the gate when the molten material is filled into the cavity, that is, the position 31b and the position 31a. Or between the position 31b and the position 31c. Thereby, the molten material filled in the injection mold is spread almost uniformly in the cavity.

  As described above, the cavity inner surface of the injection mold that forms the light reflecting surface 12 of the light guide plate 10 efficiently raises the light guided into the light guide plate 10 toward the light exit surface 13. It has a fine concavo-convex shape for forming a prism pattern, a dot pattern, and the like. The uneven shape is transferred to the filled molten material and cured, whereby various patterns are formed on the light reflecting surface 12.

  When the light guide plate 10 is actually formed by an injection mold, the runner portion 16 is also formed as shown in FIG. The runner portion 16 is an unnecessary material similar to the gate formation 15 formed by a supply path (runner) for supplying a molten material, for example, a molten acrylic resin, from a molten material supply source to an injection mold. is there. In FIG. 3, only one light guide plate 10, gate formation 15 and runner portion 16 are shown, but in reality, a plurality of light guide plates 10 are formed at a time.

  The molten molten material supplied from the molten material supply source is filled into the cavity of the injection mold through the runner and the gate. When filling the cavity with a molten material, for example, a molten acrylic resin, the pressure and temperature are controlled appropriately.

  When the filling of the molten material into the cavity is completed and the mold is cooled, the injection mold is removed, and the gate cut process is performed at the position indicated by the arrow A shown in FIG. The light guide plate 10 is cut off.

  As described above, when the light emitting diode 21 is installed, the gate formation 15 does not disturb the light guide and does not affect the light guide. As it is, it will be used as a backlight unit of a liquid crystal display device.

  FIG. 4 shows a backlight unit 80 including the light guide plate 10 and the light source unit 20 described above. In the backlight unit 80, the light source unit 20 is disposed on the light incident surface 11 side of the light guide plate 10, and the reflection sheet 81 is disposed on the light reflecting surface 12 side of the light guide plate 10, and the light emitting surface 13 side of the light guide plate 10. In addition, a diffusion sheet 82, a first prism sheet 83, and a second prism sheet 84 are arranged in an overlapping manner. The light guide plate 10, the light source 20, the reflection sheet 81, the diffusion sheet 82, the first prism sheet 83, and the second prism sheet 84 arranged in this way are a frame 85 that serves as a casing of the backlight device 80, a frame 86 is assembled so that the reflection sheet 81 faces the frame 86 and there is no rattling.

  In such a backlight device 80, the light emitted from each light emitting diode 21 included in the light source unit 20 enters the light from the light incident surface 11 of the light guide plate 10, and is guided by the light reflecting surface 12 and the reflecting sheet 81. The light is reflected and emitted from the light exit surface 13. The light emitted from the light emitting surface 13 is diffused into uniform light by the diffusion sheet 82, and both the horizontal component and the vertical component of the light are in the normal direction by the first prism sheet 83 and the second prism sheet 84. That is, the light is condensed in a direction perpendicular to the incident direction of light from the light emitting diode 21. The light emitted from the second prism sheet is emitted from the opening 85A of the frame 85 and is applied to, for example, a liquid crystal display device.

  Even when the light guide plate 30 and the light source 40 shown in FIG. 2 are used, the other configuration of the backlight unit and the light path are the same as those of the backlight unit 80, and thus the description thereof is omitted.

  Subsequently, as an example, a wedge-shaped light guide plate injection-molded using an injection mold provided with a gate at a position where the light-emitting diodes on the light incident surface are not arranged, and a guide of light incident from the light incident surface. A wedge-shaped light guide plate injection-molded using an injection mold provided with a gate on a side surface parallel to the light direction was prepared, and the brightness of each was measured. In either case, a molten acrylic resin is used as the molten material.

  First, a wedge-shaped light guide plate manufactured with an injection mold having a gate on the light incident surface will be described. As shown in FIG. 5, the light guide plate 50 has a width from the light incident surface 51 to the anti-light reflecting surface 52 of 30 mm, a width from the side surface 53 to the side surface 54 of 35 mm, and the light incident surface 51 is 25 mm × 1 mm, anti-light. The incident surface 52 has a shape of 35 mm × 0.3 mm.

  The light source unit 60 that makes light incident on the light guide plate 50 includes four chip-type light emitting diodes and light emitting diodes 61a, 61b, 61c, and 61d arranged on a substrate 63 at a pitch of 5 mm. Each light emitting diode has a size of 1 mm × 2 mm × 1 mm in length × width × height.

  The light source unit 60 is connected to the light reflecting surface 55 side of the light guide plate 50 by a double-sided tape attached to the “x” mark shown on the substrate 63. At this time, the light emitting surfaces 62 a, 62 b, 62 c, 62 d of the respective light emitting diodes are attached so as to be in close contact with the light incident surface 51 of the light guide plate 50.

  Between the position 51b and the position 51c of the light incident surface 51 of the light guide plate 50, a gate formation 55 formed by the gate of the injection mold is left. Since the distance between the position 51b and the position 51c is about 3 mm and the thickness of the light incident surface 51 is 1 mm, the area of the gate formation 55 that is in contact with the light incident surface 51 is smaller than that. Yes.

  Further, the protruding portion of the gate formation 55 is gate-cut so as to be 1 mm in accordance with the size of 1 mm in the light emitting direction of each light emitting diode.

  6, when the light emitted from the light source unit 60 attached as described above is incident on the light incident surface 51 of the light guide plate 50 illustrated in FIG. 5, the light is emitted from the light emitting surface 56. The result of measuring the brightness of the light is shown. In FIG. 6, the connected contour lines indicate the same luminance level, and it can be seen that a substantially concentric ellipse is formed by the contour lines. Therefore, it is considered that the light guide plate 50 is well injection-molded without transfer unevenness.

  Next, a wedge-shaped light guide plate manufactured with an injection mold having a gate on the side will be described. As shown in FIG. 7, the light guide plate 70 has a width from the light incident surface 71 to the anti-light reflecting surface 72 of 30 mm, a width from the side surface 73 to the side surface 74 of 35 mm, and the light incident surface 71 has a size of 25 mm × 1 mm, The light incident surface 72 is exactly the same size as the light guide plate 50 shown in FIG. 5, such as 35 mm × 0.3 mm.

  Apparently, the light guide plate 70 is different from the light guide plate 50 in two places, that there is no gate formation on the light incident surface 71 and that there is a trace 73 </ b> A that is gate cut on the side surface 73. .

  The light source unit 60 described with reference to FIG. 5 is attached to the light guide plate 70 in exactly the same manner as the light guide plate 50, and the light emitting surfaces 62a, 62b, 62c, and 62d of the respective light emitting diodes are in close contact with the light incident surface 71. Attach with double-sided tape.

  In FIG. 8, when light emitted from the light source unit 60 attached as described above is incident on the light incident surface 71 of the light guide plate 70 illustrated in FIG. 7, the light is reflected by the light reflecting surface 75. The result of having measured the brightness | luminance of the light radiate | emitted from the light-projection surface 76 is shown.

  As shown in FIG. 8, it can be seen that the connected contour lines are not concentric ellipses, but the luminance is disturbed in a region X surrounded by a solid line and indicated by diagonal lines. Region X is a position where a gate is provided, and at this position, a very high pressure is applied and molten resin is injected, so that the degree of transfer differs between left and right with respect to the incident direction of light. That is, it is considered that transfer unevenness occurs and the brightness also varies.

  As can be seen from the above results, the light guide plate 50 injection-molded with an injection mold provided with a gate between the position 51b of the light incident surface 51 and the position 51c makes the gate formation 55 light incident. Even if it is left on the surface 51, there is no uneven transfer and excellent luminance characteristics are exhibited.

It is a figure for demonstrating the light-guide plate shown as the best form for implementing this invention. It is the figure which showed another example of the same light-guide plate. In the same light-guide plate, it is the figure which showed a mode that included the runner. It is a figure for demonstrating the structure of the backlight unit carrying the light-guide plate. It is a figure for demonstrating the light guide plate manufactured concretely. It is the figure which showed the result of having measured the brightness | luminance of the same light-guide plate manufactured specifically. It is a figure for demonstrating the light-guide plate specifically provided with the gate provided in the side surface. It is the figure which showed the result of having measured the brightness | luminance of the light-guide plate which provided the gate in the side surface and manufactured specifically. It is a figure for demonstrating the light-guide plate which provided the gate in the side surface shown as a prior art, and was manufactured. It is a figure for demonstrating the light-guide plate manufactured by providing a gate in the light-incidence surface shown as a prior art. It is a figure for demonstrating the light-guide plate manufactured by providing a gate in a reflected light incident surface as a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Light guide plate, 11 Light incident surface, 11a, 11b, 11c, 11d position, 15 Gate formation, 20 Light source part, 21, 21a, 21b, 21c, 21d Light emitting diode, 22a, 22b, 22c, 22d Light emission surface, 23 substrates, 80 backlight units

Claims (8)

A light incident surface that guides light incident from a plurality of light emitting elements arranged in a row at a predetermined interval in a longitudinal direction of the light incident surface to cause surface emission; In the light guide plate with a wedge shape in which the thickness in the light guide direction gradually decreases,
When the plurality of light emitting elements are arranged in an even number of rows at predetermined intervals in the longitudinal direction of the light incident surface, the light emitting plate is filled in the cavity of the injection mold at the time of injection molding of the light guide plate. A light guide plate, wherein a gate for injecting a molten material is provided at a position between the two light emitting elements arranged in the vicinity of the center in the longitudinal direction of the light incident surface where none of the light emitting elements are arranged. A light incident surface that guides light incident from a plurality of light emitting elements arranged in a row at a predetermined interval in a longitudinal direction of the light incident surface to cause surface emission; In the light guide plate with a wedge shape in which the thickness in the light guide direction gradually decreases,
When the plurality of light emitting elements are arranged in an odd number in a row at a predetermined interval in the longitudinal direction of the light incident surface, the light emitting plate is filled in the cavity of the injection mold when the light guide plate is injection molded. Which of the light emitting elements between the light emitting element arranged at the center in the longitudinal direction of the light incident surface and the light emitting element arranged adjacent to any one of the light emitting elements is a gate for injecting a molten material. A light guide plate characterized by being provided at a position where they are not arranged. 3. The light guide plate according to claim 1, wherein the plurality of light emitting elements are light emitting diodes (LEDs). A light guide plate having a wedge shape in which the thickness of the light guided in the light guide direction gradually decreases, and guides light incident from the light incident surface to emit light from the light exit surface;
A light source having a plurality of light emitting elements arranged in a row at predetermined intervals in the longitudinal direction of the light incident surface of the light guide plate;
A reflective sheet disposed on the light reflecting surface side of the light guide plate;
A sheet material composed of a diffusion sheet and a prism sheet disposed to overlap the light output surface side of the light guide plate;
The light guide plate includes the light source, the reflective sheet, and a frame that holds the sheet material,
The light guide plate is used for injection molding when the light guide plate has an even number of light emitting elements arranged in rows at predetermined intervals in the longitudinal direction of the light incident surface. A gate for injecting a molten material to be filled in a cavity of a mold is formed of a light emitting element arranged in the center in the longitudinal direction of the light incident surface, and a light emitting element arranged adjacent to one of the light emitting elements. A backlight device characterized by being provided at a position where none of the light emitting elements are arranged . A light guide plate having a wedge shape in which the thickness of the light guided in the light guide direction gradually decreases, and guides light incident from the light incident surface to emit light from the light exit surface;
A light source having a plurality of light emitting elements arranged in a row at predetermined intervals in the longitudinal direction of the light incident surface of the light guide plate;
A reflective sheet disposed on the light reflecting surface side of the light guide plate;
A sheet material composed of a diffusion sheet and a prism sheet disposed to overlap the light output surface side of the light guide plate;
The light guide plate includes the light source, the reflective sheet, and a frame that holds the sheet material,
The light guide plate is for injection molding when the light source plate has a plurality of light emitting elements arranged in an odd number in a row at predetermined intervals in the longitudinal direction of the light incident surface. A gate for injecting a molten material to be filled in a cavity of a mold is formed of a light emitting element arranged in the center in the longitudinal direction of the light incident surface, and a light emitting element arranged adjacent to one of the light emitting elements. A backlight device characterized by being provided at a position where none of the light emitting elements are arranged . 6. The backlight device according to claim 4 , wherein the plurality of light emitting elements included in the light source are light emitting diodes (LEDs). A light incident surface that guides light incident from a plurality of light emitting elements arranged in a row at a predetermined interval in a longitudinal direction of the light incident surface to cause surface emission; In the method of manufacturing a light guide plate having a wedge shape in which the thickness in the light guide direction gradually decreases,
When the plurality of light emitting elements are arranged in an even number at a predetermined interval in the longitudinal direction of the light incident surface,
Injection of molten material to fill the injection mold from a gate provided between the two light emitting elements arranged in the vicinity of the center of the light incident surface in the longitudinal direction where none of the light emitting elements are arranged. By doing so, the said light-guide plate is injection-molded, The manufacturing method of the light-guide plate characterized by the above-mentioned. A light incident surface that guides light incident from a plurality of light emitting elements arranged in a row at a predetermined interval in a longitudinal direction of the light incident surface to cause surface emission; In the method of manufacturing a light guide plate having a wedge shape in which the thickness in the light guide direction gradually decreases,
When the plurality of light emitting elements are arranged in an odd number at a predetermined interval in the longitudinal direction of the light incident surface,
Between the light emitting element arranged at the center in the longitudinal direction of the light incident surface and the light emitting element arranged adjacent to any one of the light emitting elements, the light emitting elements are provided at positions where none of them is arranged. A method of manufacturing a light guide plate, wherein the light guide plate is injection-molded by injecting a molten material to be filled into an injection mold from a gate.

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