JP2006058333A - LIGHTING DEVICE, LIQUID CRYSTAL DISPLAY DEVICE, AND ELECTRONIC DEVICE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination device, a liquid crystal display apparatus and an electronic device having illumination light with uniform luminosity. <P>SOLUTION: A protruding portion 21 is formed in a corner of an optical sheet, while a recessed portion 11 is formed in a portion of a case 1 corresponding to the protruding portion. The optical sheet is housed in the case in a state of engaging the protruding portion with the recessed portion. The lower face of the protruding portion is fixed to the case 1 with an adhesive tape 5 applied on the recessed portion, and the upper face of the protruding portion together with the peripheral edge of the optical sheet is covered with a light shielding tape 6 to be adhered and fixed to the case. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lighting device, a liquid crystal display device, and an electronic apparatus.

  Since the liquid crystal display is a non-light emitting display element, a light source is required for the display. Depending on the type of the light source, the liquid crystal display is roughly classified into a reflective type, a transmissive type, a transflective type, and the like. The reflective type uses ambient light as a light source, and the transmissive type includes a specific light source, and uses light emitted from the specific light source. The transflective type has both characteristics of a reflective type and a transmissive type, uses ambient light and light emitted from a specific light source, and requires a specific light source as in the transmissive type.

  In these transmissive and transflective liquid crystal displays, a method of uniformly irradiating the liquid crystal display element with light emitted from a specific light source by a backlight disposed on the back surface of the liquid crystal display element has become widespread. This backlight is roughly composed of a light source, a light guide plate, optical sheets, and a casing. Each optical sheet is sequentially laminated in the casing, and is installed together with the light guide plate on the back surface of the liquid crystal display element. Light emitted from the light source is guided by the light guide plate, and further irradiated to the liquid crystal display element through various optical sheets.

  In the case of the backlight having the above configuration, the optical sheets are merely laminated in the casing and are not fixed to each other, so the optical sheets are displaced, and fine scratches and dust are generated on the surface, and the illumination light There was a problem that uniformity was lowered.

For such problems, a convex portion is provided on a part of the edge of the optical sheets, and a concave portion is provided at a position corresponding to the convex portion in the housing that accommodates the optical sheets, thereby corresponding to each other. A liquid crystal display device has been proposed in which a plurality of optical sheets can be fixed to a housing by engaging convex portions and concave portions. (See Patent Document 1.)
JP 2000-89223 A

In the liquid crystal display device described in Patent Document 1, a convex portion is provided at the center of the periphery of the optical sheet. This convex portion transmits as much light as the area and becomes brighter than the other portions, resulting in uneven brightness in the illumination light, and in particular, near the center of the edge of the display screen (near the concave portion). There is a problem that unevenness occurs.
Further, in the above configuration, the uppermost optical sheet is directly fixed to the housing. However, paying attention to each of the other optical sheets, it is merely fixed to the casing, and is not directly fixed to the casing. In addition, since the optical sheets are not fixed to each other, misalignment or rubbing occurs there, and the above problem of preventing scratches and dust generation on the optical sheet surface has not been sufficiently solved.

  The present invention has been made in order to solve the above-described problem, and an illumination device and a liquid crystal capable of obtaining uniform illumination light without uneven brightness by securely fixing each component member to a housing. It is an object to provide a display device and an electronic device.

  In order to achieve the above object, an illumination device of the present invention is an illumination device for illuminating an effective display screen of a liquid crystal display element, and includes a light source, a light guide plate, an optical sheet, and a casing, A convex portion is provided on the sheet, a concave portion is provided in a portion of the casing corresponding to the convex portion, and the optical sheet is accommodated in the casing in a state where the convex portion and the concave portion are engaged. A convex portion is provided at a corner portion of the optical sheet peripheral edge defined by an extension line of each side of the effective display screen and each peripheral edge of the optical sheet, and a lower surface of the convex portion is disposed in the concave portion. It is fixed to the housing with an adhesive tape. Furthermore, it is preferable that the upper surface of the convex portion is fixed to the housing with a light shielding tape so that the upper surface of the convex portion is covered with the periphery of the optical sheet.

  In the illuminating device of the present invention, the portion that does not affect the image display, that is, the corner portion of the optical sheet defined by the extended line of each side constituting the effective display screen and each side forming the periphery of the optical sheet. Protrusions were provided. Even if more illumination light is transmitted to this convex part than other parts, this corner part is away from the effective display screen, so there is no effect, and the illumination light on the effective display screen has uneven brightness. Does not occur.

  Moreover, when the upper surface of a convex part is coat | covered with the light shielding tape with the periphery of an optical sheet, the leakage of illumination light to a part other than a required part decreases, and uniform illumination light can be obtained.

  According to the configuration of the present invention, the optical sheet is fixed to the housing not only by engaging the convex portion and the concave portion, but also by sandwiching the upper and lower surfaces of the convex portion with the adhesive tape and the light-shielding tape, and directly Therefore, the optical sheets are not displaced from the casing or rubbed against each other. Therefore, the generation of scratches and dust can be reduced as much as possible, and uniform illumination light can be obtained.

  In addition, by arranging adhesive tape in the recesses, each optical sheet is immediately bonded and fixed to the predetermined position of the housing with adhesive tape even when sequentially stacking multiple optical sheets. There is also an advantage that the work efficiency is improved.

It is desirable that the recess provided in the housing has a tapered shape in which the cross-sectional shape widens toward the opening.
When the side wall of the concave portion is inclined with respect to the depth direction to have a tapered shape, the angle of the opening end becomes an obtuse angle. When the side wall is upright without being inclined and the angle of the opening end is a right angle, when the light shielding tape is applied so as to cover the concave portion and the upper surface of the convex portion, the light shielding tape is enlarged at the opening end of the concave portion. It is necessary to bend. On the other hand, if the opening end of the concave portion has an obtuse angle, the light shielding tape can be bent at a small angle and no gap is formed between the light shielding tape and the convex portion. Furthermore, since the adhesion area to the convex part of a light shielding tape becomes large compared with the case where a side wall stands upright, an optical sheet can be fixed more reliably.
Furthermore, since the opening area of the concave portion is larger than the bottom surface, the convex portion can be easily engaged with the concave portion, and the optical sheet can be easily mounted on the housing.

When the optical sheet is composed of a plurality of sheets, the depth of the recess is preferably equal to the sum of the laminated thickness of the optical sheets and the film thickness of the adhesive tape.
By adjusting the depth of the concave portion as described above, the convex portion can be accommodated in the concave portion without a gap, and the optical sheet can be prevented from floating from the housing. In addition, since the film thickness of the adhesive tape that becomes the glue margin when bonding each optical sheet can be accommodated in the recess, the glue margin is not added to the overall thickness of the housing. Since the thickness of the adhesive tape can be incorporated into the entire thickness of the housing, the upper surface becomes flat, and the lighting device can be made thinner accordingly.

When the optical sheet is composed of a plurality of sheets, it is desirable that the convex portions provided on each optical sheet do not overlap each other.
When a plurality of optical sheets are stacked and accommodated in a housing, if the convex portions of the optical sheets do not overlap each other at the corners of the optical sheets, the lower surface of each convex portion is With the adhesive tape, the upper surface will be glued so as to be sandwiched between them, and any optical sheet will be directly fixed to the housing at the upper and lower surfaces of each convex part, and between each optical sheet Misalignment and rubbing will not occur. Accordingly, generation of scratches and dust can be suppressed, and uniform illumination light can be obtained. Further, even when used for a long period of time, the optical sheet will not be displaced or rubbed, and the uniformity of illumination light can be prevented from decreasing over time.
Furthermore, even if there are a plurality of optical sheets, the members for fixing them are only a pair of tapes of an adhesive tape and a light-shielding tape, and no additional adhesive members are required. Miniaturization is possible.

Furthermore, a convex portion is provided at the corner of the periphery of the light guide plate defined by the extension line of each side of the effective display screen of the light guide plate and each side of the peripheral edge of the light guide plate, and this convex portion is engaged with the concave portion of the housing. In addition, it is desirable that the lower surface of the convex portion is fixed to the housing with an adhesive tape disposed on the bottom surface of the concave portion, and the upper surface of the convex portion is covered with a peripheral surface of the optical sheet with a light shielding tape.
Similar to the fixing structure of the optical sheet, if the light guide plate is housed in the casing together with the optical sheet, the lighting device can be further reduced in size. Further, the light guide plate and other members are not displaced or rubbed, and uniform illumination light can be obtained.

The convex portion of the light guide plate and the convex portion of the optical sheet do not overlap each other.
If the light guide plate is also provided with a convex portion, and this convex portion is fixed in the housing so as not to overlap with the convex portion of the optical sheet, it is possible to prevent displacement and rubbing between the light guide plate and other members, Stable illumination light with uniform luminance can be obtained. Furthermore, according to this configuration, both the light guide plate and the optical sheet, which are the main members of the lighting device, can be securely and easily fixed in the housing, the work efficiency in the manufacturing process can be improved, and an inexpensive and high-quality product. Can provide.

A liquid crystal display device of the present invention includes the above-described illumination device of the present invention and an image display liquid crystal display element on which illumination light emitted from the illumination device is incident.
An electronic apparatus according to the present invention includes the liquid crystal display device according to the present invention described above. According to the liquid crystal display device and the electronic apparatus of the present invention, since the illumination device of the present invention described above is provided, not only can an image be displayed with illumination light with uniform brightness, but also illumination light can be used over a long period of use. Therefore, the liquid crystal display device and the electronic apparatus having good display quality can be obtained. In addition, the downsizing of the lighting device enables the liquid crystal display device and the electronic device including the lighting device to be downsized.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. In each drawing referred to below, the film thicknesses and dimensional ratios of the respective components are appropriately changed for easy understanding of the drawings. ing.

[Lighting device]
(First embodiment)
The illumination device according to the present embodiment includes a light source, a light guide plate that transmits light emitted from the light source, and an optical sheet that refracts or reflects illumination light emitted from the light guide plate and irradiates the image display element as illumination light. And a housing for housing the optical sheet.
The light source is not particularly limited, and is a cold cathode tube, LED (Light Emitting Diode), hot cathode tube, organic EL (Electroluminescence), Xe discharge tube, electrodeless lamp, or the like. These may be used alone, or an auxiliary light source may be added to the main light source, and a plurality of the same or different light sources may be used in combination.

  The light guide plate transmits light emitted from the light source and emits it as illumination light of the image display element, and is disposed so as to face the light emitting portion of the light source. In the case of a planar light guide plate, for example, it is made of a transparent acrylic resin plate, and light emitted from the light source enters from its side surface and repeats total reflection in the inside thereof so as to go straight. A plurality of grooves, holes, and the like are formed on the lower back surface of the planar light guide plate. By changing the incident angle of the light emitted from the light source, the surface emitting light is emitted from the upper emission surface. It can be emitted as light.

  The optical sheet is used to change the light emitted from the light guide plate into illumination light having a predetermined characteristic, and is appropriately selected depending on the application. For example, a diffusion sheet for making the surface brightness of the illumination light emitted from the light guide plate uniform, a prism sheet for directing and collecting the illumination light toward the image display element, and leaking from the back surface of the light guide plate For example, a reflection sheet that reflects light and re-enters the light guide plate. These may be used alone or in combination of a plurality of various optical sheets. Usually, these optical sheets are housed in a casing and disposed on the light exit surface of the light guide plate, while the reflection sheet is disposed on the light exit surface of the light guide plate.

FIG. 1 is a schematic plan view showing a housing that accommodates an optical sheet, FIG. 2 is a schematic configuration diagram seen through the laminated state, and FIG. 3 is taken along the line AA ′ of FIG. It is sectional drawing. 4A to 4F are component configuration diagrams in which the respective members accommodated in the housing are arranged in the stacking order from the side close to the light guide plate toward the emission direction.
The casing 1 is a molded resin frame. In the present embodiment, the casing 1 guides the diffusion sheet 2, the first prism sheet 3, and the second prism sheet 4 as optical sheets. They are stacked and accommodated in order from the exit surface side of the optical plate.

  These optical sheets 2, 3, 4 are substantially rectangular, and are provided with convex portions 21, 31, 41 projecting outward from the short sides of the rectangle. A concave portion 11 is provided in a portion (upper surface) of the housing 1 corresponding to each convex portion 21, 31, 41, and the convex portions 21, 31, 41 are engaged with each other. The lower surfaces of these convex portions 21, 31, 41 are bonded to the concave portions 11 with the adhesive tape 5, and the upper surfaces thereof are bonded to the housing 1 with the light shielding tape 6. The adhesive tape 5 is a double-sided adhesive tape that covers the bottom and side walls of the recess 11 and further extends to the periphery of the opening of the recess 11. The light-shielding tape 6 is a light-shielding adhesive tape that covers the entire upper surface of the convex portions 21, 31, 41, and further forms a frame on the outside of the effective display screen 7 of the second prism sheet 4 that is the uppermost layer. Covered and adhered to the housing 1.

  The convex portions 21, 31, and 41 are four corner portions of the optical sheets 2, 3, and 4, that is, the effective display screen 7 of the image display element such as a liquid crystal panel (shown by a one-dot broken line in FIG. 2). It is provided in a region surrounded by the extension line 71 of each side constituting each side and each side forming the periphery of each optical sheet 2, 3, 4. This area is a part that does not affect the image quality of the effective display screen 7, and even if a large amount of illumination light corresponding to the area is transmitted to each convex part 21, 31, 41, the corner part Is away from the effective display screen 7, luminance unevenness does not occur in the illumination light. Furthermore, even when the screen is viewed from an oblique direction rather than from the vertical direction with respect to the display screen, if the convex portion is provided at the corner portion, the convex portion and the illumination light leaking from the convex portion are difficult to see. There is also.

The concave portion 11 that engages the convex portions 21, 31, 41 has a tapered shape whose cross-sectional shape extends toward the opening.
When the side wall of the recess 11 is inclined with respect to the depth direction to have a tapered shape, the angle of the open end 12 becomes an obtuse angle. When the side wall is upright without being inclined and the angle of the opening end 12 is a right angle, when the upper surface of the convex portions 21, 31, 41 is covered with the light shielding tape 6, the light shielding tape 6 is attached to the opening end of the concave portion 11. It is necessary to bend the part 12 greatly. On the other hand, as shown in FIG. 3, if the opening end 12 of the recess 11 has an obtuse angle, even if the degree of bending of the light shielding tape 6 is small, the light shielding tape 6 can be connected to the recess 11 and the convex portions 21, 31, 31. It is possible to sufficiently follow the shape of 41, and no gap is generated between the light shielding tape 6 and the convex portions 21, 31, 41. In addition, since the adhesion area of the light shielding tape 6 to the convex portions 21, 31, 41 is increased, the optical sheets 2, 3, 4 can be reliably adhered to the housing 1. Furthermore, if the concave portion 11 is tapered, the opening is larger than the bottom surface thereof, so that the convex portions 21, 31, 41 can be easily engaged with the concave portion 11, and the housing of the optical sheets 2, 3, 4 is easy to engage. Mounting on the body 1 is facilitated.

The depth of the recess 11 is set to be equal to the sum of the laminated thickness of the optical sheets 2, 3 and 4 and the film thickness of the adhesive tape 5.
The depth of the recess 112 with respect to the projection 21 of the lowermost diffusion sheet 2 is set to the total thickness of the diffusion sheet 2 and the two prism sheets 3 and 4 laminated on the diffusion sheet 2. Shall be added. The depth of the concave portion 113 with respect to the convex portion 31 of the first prism sheet 3 is obtained by adding the thickness of the adhesive tape to the total thickness of the diffusion sheet 2 and the first prism sheet 3. The depth of the concave portion 114 with respect to the convex portion 41 of the second prism sheet 4 that is the uppermost layer is made equal to the sum of the film thickness of the second prism sheet 4 and the film thickness of the adhesive tape 5. Thereby, not only the surface position of the upper surface of the second prism sheet 4 and the housing 1 can be matched, but also the thickness of the adhesive tape 5 serving as an adhesive margin can be incorporated as the thickness of the housing 1. In addition, the lighting device can be made thinner by the thickness of the adhesive tape while the upper surface becomes flat.
Further, by setting the depth of the recesses in this way, the optical sheets 2, 3, 4 can be stacked without causing a gap, and the optical sheets 2, 3, 4 from the housing 1 can be stacked. Can be prevented.

  The convex portions 21, 31, and 41 are provided so as not to overlap each other at the corner portions of the optical sheets 2, 3, and 4, and the corresponding concave portions 112, 113, and 114 are provided in the housing 1 in a stepped manner. . As a result, the lower surfaces of the convex portions 21, 31, 41 are bonded to the housing 1 by the adhesive tape 5, and the upper surfaces are bonded by the light shielding tape 6. In any optical sheet, each convex portion 21, 31, 41 is sandwiched between the adhesive tape 5 and the light shielding tape 6, and directly adhered and fixed to the housing 1. Therefore, the optical sheets 2, 3, and 4 are not displaced or rubbed, and the generation of scratches and dust can be suppressed, so that illumination light with uniform brightness can be obtained. Further, even when used for a long period of time, the optical sheet is not displaced or rubbed, and the luminance of the illumination light can be prevented from decreasing with time.

  The adhesive tape 5 disposed in the concave portion 11 not only bonds and fixes the lower surface of the convex portion, but also serves as a temporary fixing tape when the optical sheets 2, 3, 4 are stacked and stored in the housing 1. Can be used. When the diffusion sheet 2, the first prism sheet 3, and the second prism sheet 4 are sequentially stacked on the concave portion 11 of the housing 1 in order from the lower layer, the respective convex portions are simultaneously placed on the concave portion 11. Is temporarily fixed and adhered to the predetermined position with the adhesive tape 5, and the position does not shift. This has the advantage that the working efficiency at the time of manufacture increases. In addition, since the second prism sheet 4 as the uppermost layer is laminated and completely adhered to the housing 1 with the light shielding tape 6, the optical sheets 2, 3, and 4 do not move. It is possible to further reduce the occurrence of luminance unevenness of the illumination light caused by deviation or rubbing.

  In the lighting device of the present invention, even if there are a plurality of optical sheets 2, 3, 4, the members for fixing them are only the adhesive tape 5 and the light shielding tape 6, and no separate adhesive member is required. Therefore, the number of components of the lighting device can be reduced and the size can be reduced. In particular, the adhesive tape 5 only needs to be disposed not on the entire surface of the housing 1 but only in the vicinity of the recess 11 and its opening, so that the optical sheet can be fixed at a low cost.

  Further, since the upper surfaces of the convex portions 21, 31, 41 are covered with the light shielding tape 6 in a frame shape so as to surround the outside of the effective display screen 7 together with the peripheral edges of the optical sheets 2, 3, 4, respectively. There is no light leakage, and uniform illumination light can be obtained more efficiently.

  Further, if the light shielding tape 6 has a double-sided adhesive property, the housing 1 containing the optical sheet can be directly bonded to the image display element, which is preferable because the size and the manufacturing process can be simplified.

(Second Embodiment)
Furthermore, in the illumination device of the present invention, a light guide plate may be accommodated in the housing 1 in addition to the optical sheets 2, 3, and 4. Adhesion and fixing of the light guide plate to the housing 1 can be performed in exactly the same manner as the optical sheets 2, 3, and 4. That is, if a convex portion is provided at the corner portion of the light guide plate, the convex portion is engaged with the concave portion of the housing 1, and both sides of the convex portion are fixed by being sandwiched between the adhesive tape 5 and the light shielding tape 6. Good. Similar to the convex portions of the optical sheet, the convex portions of the light guide plate are formed at the corner portions surrounded by the extended lines 71 of the sides constituting the effective display screen 7 and the peripheral sides of the light guide plate. What is necessary is just to provide in the position which does not overlap with each convex part of a sheet | seat. In addition, in the same manner, the reflection sheet can be accommodated in the casing on the surface opposite to the light emission side of the light guide plate, that is, the lowermost layer side. According to this configuration, all of the light guide plate and various optical sheets necessary for obtaining desired illumination light can be accommodated in the housing 1, so that the size of the illumination device can be reduced and the number of components can be reduced. This is preferable.

[Liquid Crystal Display]
The liquid crystal display device of the present invention is composed of the illumination device of the present invention and a liquid crystal cell, and the illumination light is incident on the liquid crystal cell from this illumination device to display an image. In the liquid crystal display device of the present invention, since there is no luminance unevenness in the illumination light, it is possible to display a high-quality image that is clear and has good visibility. In addition, since the illumination light does not change with time, the display device has a long lifetime. Further, since the lighting device is downsized, the entire display device can be downsized.

[Electronics]
FIG. 6 is a perspective view showing an example of an electronic apparatus equipped with the liquid crystal display device of the present invention. A cellular phone 1000 shown in FIG. 6 includes the liquid crystal display device of the present invention as its display unit 1001.

  The electronic device of the present invention is not limited to the above mobile phone, but an electronic book, a personal computer, a digital still camera, a liquid crystal television, a viewfinder type or a monitor direct view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, It can be suitably used as an image display means for a word processor, a workstation, a video phone, a POS terminal, a device equipped with a touch panel, or the like.

  The present invention is not limited to the above-described embodiments, and includes various modifications made to the above-described embodiments without departing from the spirit of the present invention.

The schematic plan view which shows one Embodiment of the illuminating device of this invention. The schematic block diagram which shows one Embodiment of the illuminating device of this invention. FIG. 3 is a schematic cross-sectional view taken along line AA ′ of the lighting device shown in FIG. 2. Schematic of the structural member in one Embodiment of the illuminating device of this invention. FIG. 14 is a perspective view illustrating an example of an electronic device of the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Housing | casing, 11 ... Concave part, 2 ... Diffusion sheet, 3 ... 1st prism sheet, 4 ... 2nd prism sheet, 5 ... Adhesive tape, 6 ... Shading tape, 7 ... Effective display screen, 21 ... Convex part , 31 ... convex part, 41 ... convex part, 1000 ... electronic device, 1001 ... display part.

Claims (10)

An illumination device for illuminating an effective display screen of a liquid crystal display element,
A light source, a light guide plate, an optical sheet, and a housing are provided. The optical sheet is provided with a convex portion, and a concave portion is provided in a portion of the housing corresponding to the convex portion, and the convex portion and the concave portion are engaged with each other. The optical sheet is housed in the housing in a state of being
The convex portion is provided at a corner portion of the periphery of the optical sheet defined by an extension line of each side of the effective display screen and each peripheral edge of the optical sheet, and a lower surface of the convex portion is disposed in the concave portion. The lighting device is fixed to the housing with an adhesive tape.   The lighting device according to claim 1, wherein the upper surface of the convex portion is fixed to the housing with a light shielding tape so as to be covered with a peripheral edge of the optical sheet.   The lighting device according to claim 1, wherein the recess has a tapered shape in which a cross-sectional shape widens toward the opening.   The optical sheet is composed of a plurality of sheets, and the depth of the recess is equal to the sum of the laminated thickness of the optical sheets and the film thickness of the adhesive tape. The lighting device according to one item.   5. The optical sheet according to claim 1, wherein the optical sheet is composed of a plurality of sheets, and the protrusions provided on the optical sheets are provided at positions that do not overlap each other. Lighting device.   A convex portion is provided at a corner portion of the periphery of the light guide plate defined by an extension line of each side of the effective display screen on the light guide plate and each peripheral edge of the light guide plate, and the convex portion is a concave portion of the casing. 6. The illumination according to claim 1, wherein the lower surface of the convex portion is fixed to the casing with an adhesive tape disposed on the bottom surface of the concave portion. apparatus.   The lighting device according to claim 1, wherein an upper surface of the convex portion is fixed to the housing with a light shielding tape so as to be covered with a peripheral edge of the optical sheet.   The lighting device according to claim 6, wherein the convex portion of the light guide plate and the convex portion of the optical sheet are provided at positions that do not overlap each other.   A liquid crystal display device comprising: the illuminating device according to claim 1; and a liquid crystal display element into which illumination light emitted from the illuminating device is incident. An electronic apparatus comprising the liquid crystal display device according to claim 9.

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