JP2005108517A - Light guide plate, liquid crystal display device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide plate without generating a bright line on a liquid crystal display device; and to provide a liquid crystal display device and an electronic apparatus using the light guide plate. <P>SOLUTION: This sheet-like and rectangular light guide plate 42 uses a surface facing to a screen of a display panel as a light emission surface 51, and is used for injecting light from an incident side surface 52 generally perpendicular to the light emission surface 51 to guide the light to the light emission surface 51. The light guide plate is characterized by that irregularity is not formed in the long-side directions of side surfaces 53-55 in areas R1 and R2 formed by projecting an effective light emission area 56 on the light emission surface 51 equivalent to the display area of the display panel to the side surfaces 53-55 other than the incident side surface 52. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light guide plate used as a part of a backup light unit of a liquid crystal display device, a liquid crystal display device using the light guide plate, and an electronic apparatus.

  Liquid crystal display devices are used in portable information terminals such as cellular phones and PDAs (Personal Digital Assistants). A conventional liquid crystal display device includes a liquid crystal display panel, a backlight disposed adjacent to the liquid crystal display panel, and a frame that accommodates the backlight. The liquid crystal display panel includes a pair of panel substrates, a sealing material formed between the pair of panel substrates along the outer periphery of the panel substrate, and a liquid crystal disposed in a region surrounded by the pair of panel substrates and the sealing material. And a driving circuit such as a semiconductor device for driving the liquid crystal. For example, the drive circuit is directly mounted on one panel substrate constituting the liquid crystal display panel or mounted on the flexible wiring substrate, and this flexible wiring substrate constitutes one liquid crystal display panel. Is electrically connected. In addition, the backlight includes a light guide plate and a sheet-like optical component including a reflection sheet that is overlapped with the light guide plate, and a light source unit that makes light incident on the light guide plate from the side of the light guide plate. The backlight having such a configuration is accommodated in the frame, and the liquid crystal display panel is bonded to the accommodated light guide plate by an adhesive sheet or the like.

  FIG. 6 is a plan view showing the shape of a light guide plate used in a conventional backlight. The light guide plate 200 has a shape slightly larger than a region where the liquid crystal of the liquid crystal display panel is sandwiched in plan, and a claw-like protrusion 201 is provided at a part of the edge. When the light guide plate 200 is housed in the frame in order to assemble the liquid crystal display device, the light guide plate 200 is fixed in the frame by fitting the protruding portion 201 of the light guide plate 200 into the recess formed in the frame. (For example, refer to Patent Document 1).

Japanese Patent Laying-Open No. 2003-66418 (FIG. 6)

  However, in the light guide plate 200 used in the conventional backlight, the protruding portion 201 provided on the edge portion other than the incident side on which the light emitting element is disposed has a streak-like light (hereinafter referred to as a bright line) by light from the reflection sheet or the like. There was a problem of causing 210 to occur. The bright line 210 is not a problem when the liquid crystal display device is observed in a normal state, but appears depending on the angle at which the liquid crystal display device is observed, and makes it difficult to observe the image displayed on the liquid crystal display panel. .

  The present invention has been made in view of the above, and an object thereof is to provide a light guide plate in which no bright line is generated in a liquid crystal display device, and a liquid crystal display device and an electronic apparatus using the light guide plate.

  In order to solve the above-described problems and achieve the object, the light guide plate according to the present invention has a light-emitting surface as a surface facing the display surface of the display panel, and light is incident from an incident side surface substantially perpendicular to the light-emitting surface. A sheet-like rectangular light guide plate that guides light to the light emitting surface, in an area where an effective light emitting region on the light emitting surface equal to the display region of the display panel is projected on a side surface other than the incident side surface, Unevenness is not formed in the long side direction of the side surface. Thereby, a bright line is not produced by unevenness | corrugations, such as a protrusion part formed in side surfaces other than the incident side surface of a light-guide plate. As a result, light can be uniformly irradiated over the entire display surface of the display panel.

  In addition, a liquid crystal display device according to the present invention supports a liquid crystal display panel having a liquid crystal display function, a rectangular light guide plate having a light emitting surface disposed opposite to the display surface of the liquid crystal display panel, and the light guide plate. A light-emitting element that provides light to an incident side surface substantially perpendicular to the light-emitting surface of the light guide plate to function as a backlight to the liquid crystal display panel, and a surface of the light guide plate that faces the liquid crystal display panel A liquid crystal display device having a reflecting member disposed on the reflecting member for reflecting the light guided to the light guide plate provided by the light emitting element, wherein the light guide plate has a liquid crystal display on a side surface other than the incident side surface. Protruding portions for connecting to the support member are provided so that no irregularities are formed in the long side direction of the side surface within the region where the effective light emitting region on the light emitting surface, which is equal to the display area of the panel, is projected onto the side surface. Shi The support member is characterized by having a recess corresponding to the projecting portion for supporting the light guide plate. Thereby, a bright line is not produced by unevenness | corrugations, such as a protrusion part formed in side surfaces other than the incident side surface of a light-guide plate. As a result, light can be irradiated uniformly over the entire display surface of the liquid crystal display panel, and the visibility of the liquid crystal display panel does not change depending on the viewing direction.

  An electronic apparatus according to the present invention includes the liquid crystal display device according to the above-described invention. Accordingly, an electronic device in which bright lines are not generated by unevenness such as protrusions formed on side surfaces other than the incident side surface of the light guide plate can be provided, and display quality of the electronic device can be improved.

  Exemplary embodiments of a light guide plate, a liquid crystal display device, and an electronic apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by these Examples.

  FIG. 1 is a perspective exploded view showing an example of a schematic configuration of a liquid crystal display device using a light guide plate according to the present invention. The liquid crystal display device has a configuration in which a liquid crystal display panel 2 and a backlight unit 4 for irradiating the liquid crystal display panel 2 are connected via a flexible wiring board 3.

  The liquid crystal display panel 2 is configured such that a first panel substrate 21 and a second panel substrate 22 are bonded together via a sealing material (not shown), and liquid crystal (not shown) is enclosed in the two bonded panel substrates. The Electrodes (not shown) for controlling the liquid crystal are formed in a matrix on the surfaces of the first and second panel substrates 21 and 22 on the side where the liquid crystal is sealed. The second panel substrate 22 has an overhang region 23 that projects to one side with respect to the first panel substrate 21. A drive circuit connected to the electrodes formed on the first and second panel substrates 21 and 22 is provided on the overhang region 23.

  The backlight unit 4 is provided on the second panel substrate 22 side of the liquid crystal display panel 2, and a light emitting element 41 such as a laser diode, a light guide plate 42 that guides light from the light emitting element 41, and a second light guide plate 42. The reflection sheet 43 bonded on the surface opposite to the panel substrate 22 has a configuration housed in the frame 44. On the side surface of the frame 44 where the light emitting element 41 is disposed and the side surface opposite to the side surface, concave portions corresponding to protrusions 62 and 64 formed on the light guide plate 42 described later so as to fix the light guide plate 42 accommodated therein. 71, 72 are formed. In addition, a support frame 73 for supporting the light guide plate 42 is formed at an interval slightly narrower than the width of the light guide plate 42 on the other side surface orthogonal to these side surfaces. The reflection sheet 43 corresponds to the reflection member in the claims, and the frame 44 also corresponds to the support member.

  The flexible wiring board 3 has a function of electrically connecting electrodes and electronic components formed on the liquid crystal display panel 2 and electronic components on the backlight unit 4 and is made of a flexible material. . In the case of FIG. 1, the vicinity of one edge portion of the flexible wiring board 3 is joined into the overhanging region 23 of the second panel substrate 22 by a double-sided tape or the like, and the vicinity of the other edge portion is Although not illustrated, the backlight unit 4 is bent toward the reflection sheet 43 and joined to the reflection sheet 43 with a double-sided tape or the like. The light emitting element 41 of the backlight unit 4 is mounted on the flexible wiring board 3 so as to be provided at a predetermined position of the light guide plate 42 attached to the frame 44.

  FIGS. 2-1 to 2-3 are diagrams showing an example of the structure of the light guide plate according to the present invention, FIG. 2-1 is a plan view of the light guide plate, and FIG. FIG. 2C is a side view of the light guide plate, and FIG. 2C is a cross-sectional view taken along line AA of the light guide plate in FIG. 2A. In the present invention, the surface of the light guide plate 42 substantially parallel to the display surface of the liquid crystal display panel 2 is referred to as a light emitting surface 51, and surfaces substantially perpendicular to the light emitting surface 51 are referred to as side surfaces 52 to 55. Of these, the side surface on which the light emitting element 41 is disposed is referred to as the incident side surface 52. In addition, when it is necessary to specify the side surface of the light guide plate 42 for explanation, the right side surface toward the incident side surface 52 is called a right side surface 53 and the left side surface toward the incident side surface 52 in FIG. The side surface opposite to the incident side surface 52 is referred to as the left side surface 54, and the rear side surface 55 is referred to as the rear side surface 55. Further, an area on the light emitting surface 51 of the light guide plate 42 corresponding to a display area where display is performed on the liquid crystal display panel 2 is referred to as an effective light emitting area 56.

  On the incident side surface 52 of the light guide plate 42, a light incident portion 61 provided to face the light emitting surface of the light emitting element 41 and a protruding portion 62 fitted to the concave portion 71 of the frame 44 are provided. In addition, a protrusion 63 is provided on the upper side of the right side surface 53 and the left side surface 54 so as to protrude outward from the effective light emitting region 56. Further, the rear side surface 55 of the light guide plate 42 is provided with a protrusion 64 having a width equal to or larger than the width of the effective light emitting region 56 and fitted to the recess 72 of the frame 44. The light guide plate 42 having such a configuration is fixed at the mounting position in the frame 44 by the protrusions 62 and 64 provided on the incident side surface 52 and the rear side surface 55, and is provided on the left side surface 54 and the right side surface 53. 63, a step is formed on the left side surface 54 and the right side surface 53, and further supported by the support frame 73 of the frame 44 by this step.

  As shown in FIGS. 2-1 to 2-3, the light guide plate 42 according to the present invention includes an effective light emitting area 56 projected on the side faces 53 to 55 other than the incident side face 52, and the side faces 53 to 55. Unevenness is not formed in the long side direction. Under such conditions, when connecting means to the frame 44 such as the protrusions 63 and 64 is provided on the side surfaces 53 to 55 other than the incident side surface 52, no bright line is generated in the effective light emitting region 56. .

  For example, the side surface X of the protruding portion 64 of the rear side surface 55 in FIG. Therefore, in order not to generate bright lines in the effective light emitting region 56, it is necessary to provide the side surface X outside the projection region R1 in which the effective light emitting region 56 is projected on the rear side surface 55 of the light guide plate 42. On the other hand, the side surface Y1 of the protruding portion 64 of the rear side surface 55 shown in FIG. Further, the side surface Y2 constituting the protruding portion 63 of the right side surface 53 and the left side surface 54 shown in FIG. 2-2 or FIG. 2-3 does not form irregularities in the long side direction of the right side surface 53 or the left side surface 54. Therefore, the side surfaces Y1 and Y2 of the protrusions 63 and 64 may be provided inside the projection regions R1 and R2 in which the effective light emitting region 56 is projected on the rear side surface 55, the right side surface 53, or the left side surface 54 of the light guide plate 42. Good. Further, a notch 65 exists between the incident side surface 52 and the right side surface 53 and between the incident side surface 52 and the left side surface 54. Both corners 65a formed by the notch portions 65 are provided. The effective light emitting area 56 is not projected on the right side surface 53 and the left side surface 54 and is not inside the projection region R2. Therefore, no bright line is generated in the effective light emitting region 56 by the corner portion 65 a of the notch portion 65.

  Next, an outline of a method for housing the light guide plate 42 in the frame 44 and a method for assembling the liquid crystal display device will be described. The reflection sheet 43 is attached to one light emitting surface of the light guide plate 42, and the protrusions 62 and 64 of the light guide plate 42 are inserted into the recesses 71 and 72 of the frame 44 as shown in FIG. 42 is fixed. At this time, the step formed by the protrusions 63 formed on the right side surface 53 and the left side surface 54 of the light guide plate 42 is just caught by the support frame 73 of the frame 44, and the light guide plate 42 is also fixed by the support frame 73. Is done. Thereafter, the liquid crystal display panel 2 having the flexible wiring board 3 fixed to the overhanging region 23 is attached on the light emitting surface 51 of the light guide plate 42 to which the reflection sheet 43 is not attached. Further, the side of the flexible wiring board 3 on which the light emitting element 41 is mounted is bent to the bottom side of the frame 44. Then, alignment is performed so that the light emitting element 41 is aligned with the light incident portion 61 of the light guide plate 42, and the reflection sheet 43 on the bottom surface side of the frame 44 and one edge portion of the flexible wiring board 3 are bonded with a double-sided tape or the like. paste. In this way, a liquid crystal display device is formed.

  According to the first embodiment, in the projection region in which the effective light emitting region 56 is projected on the side surface other than the incident side surface 52, there is no protrusion or the like that forms irregular shapes such as irregularities in the long side direction of the side surfaces 53 to 55. With this configuration, when the light from the light emitting element 41 is irradiated onto the light guide plate 42, bright lines due to the projections and depressions of the protruding portions do not occur in the effective light emitting region 56. Further, according to the liquid crystal display device provided with such a light guide plate 42, no bright line is generated in the effective light emitting region 56, and even display is possible even when the observer changes the angle at which the liquid crystal display panel 2 is observed. Can be provided.

  In the second embodiment, a specific example of an electronic device including the liquid crystal display device having the light guide plate described in the first embodiment will be described. 3-5 is an example of an electronic device provided with the liquid crystal display device using the light-guide plate concerning this invention, respectively. FIG. 3 is a perspective view illustrating an example of a mobile phone. Reference numeral 100 denotes a mobile phone body, of which 101 is a display unit comprising a liquid crystal display device using the light guide plate of the present invention. FIG. 4 is a perspective view illustrating an example of a wristwatch-type electronic device. Reference numeral 110 denotes a watch main body with a built-in watch function, and 111 denotes a display unit comprising a liquid crystal display device using the light guide plate of the present invention. FIG. 5 is a perspective view showing an example of a portable information processing apparatus such as a word processor or a personal computer. In FIG. 5, reference numeral 120 denotes a portable information processing device, 122 denotes an input unit such as a keyboard, 124 denotes an information processing device main unit storing arithmetic means, storage means, and the like, and 126 denotes the present invention. It is a display part which consists of a liquid crystal display device which uses this light-guide plate.

  Moreover, as an electronic device provided with a liquid crystal display device using such a light guide plate, the mobile phone shown in FIG. 3, the wristwatch-type electronic device shown in FIG. 4, and the portable information processing device shown in FIG. In addition, for example, digital still cameras, in-vehicle monitors, digital video cameras, viewfinder type or monitor direct-view type video tape recorders, car navigation devices, pagers, electronic notebooks, calculators, workstations, video phones, POS terminals, etc. An electronic apparatus including an electro-optical device can be given.

  As described above, the light guide plate according to the present invention is useful for a liquid crystal display device that performs display by guiding light to the entire display surface using light emitted from a light emitting element.

It is a disassembled perspective view which shows schematic structure of a liquid crystal display device. It is a top view which shows an example of the structure of the light-guide plate of this invention. It is a side view which shows an example of the structure of the light-guide plate of this invention. It is AA sectional drawing of FIGS. It is a figure which shows an example of an electronic device. It is a figure which shows an example of an electronic device. It is a figure which shows an example of an electronic device. It is a top view which shows the structure of the conventional light-guide plate.

Explanation of symbols

42 light guide plate, 51 light emitting surface, 52 incident side surface, 53 right side surface, 54 left side surface, 55 rear side surface, 56 effective light emitting region, 61 incident portion, 62 to 64 protruding portion

Claims (3)

A surface facing the display surface of the display panel is a light emitting surface, a sheet-like rectangular light guide plate that guides light to the light emitting surface by entering light from an incident side surface substantially perpendicular to the light emitting surface,
The light guide plate is characterized in that no unevenness is formed in the long side direction of the side surface in a region obtained by projecting an effective light emitting region on the light emitting surface equal to the display region of the display panel onto a side surface other than the incident side surface. A liquid crystal display panel having a liquid crystal display function; a rectangular light guide plate having a light emitting surface disposed opposite to a display surface of the liquid crystal display panel; a support member supporting the light guide plate; In order to function as a backlight, a light emitting element that provides light to an incident side surface that is substantially perpendicular to a light emitting surface of the light guide plate, and a light emitting element that is disposed on a surface of the light guide plate that faces the liquid crystal display panel and that the light emitting element provides A liquid crystal display device having a reflective member that reflects light guided to the light guide plate,
The light guide plate has no irregularities formed on the side surfaces other than the incident side surface in the long side direction of the side surface in a region where an effective light emitting region on the light emitting surface equal to the display region of the display panel is projected on the side surface. And having a protrusion for connecting to the support member,
The liquid crystal display device, wherein the support member has a concave portion corresponding to the protruding portion for supporting the light guide plate.   An electronic apparatus comprising the liquid crystal display device according to claim 2.

Images