JP4172768B2 - Lighting device for liquid crystal display panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lighting device for a liquid crystal display panel, and more particularly to a technique for laminating optical sheets disposed on a light exit surface side of a light guide plate.
[0002]
[Prior art]
There are two types of lighting devices for liquid crystal display panels: the direct type and the sidelight type. Since the sidelight type can be made thinner than the direct type, mobile devices, especially mobile phones, where small size, light weight and thickness are important as products. Is often used. First, the general configuration will be described with reference to FIG.
[0003]
The sidelight type illumination device includes a light guide plate (light guide) 10 disposed on the back side (counter observation side) of the liquid crystal display panel P shown in the upper part of FIG. A light source 20 for irradiating light to the light guide plate 10 is disposed on the side with the predetermined side surface as the light incident surface 11. As the light source 20, a chip-type light emitting diode is usually used.
[0004]
A reflection sheet 12 is provided on the bottom surface of the light guide plate 10, and light incident from the light incident surface 11 is irradiated toward the liquid crystal display panel P from a light emission surface (upper surface) 13 on the opposite side of the reflection sheet 12. Is done.
[0005]
On the light emitting surface 13 side of the light guide plate 10, optical sheets 30 for optimizing the irradiation light to the liquid crystal display panel P are arranged. The optical sheets 30 include a plurality of optical sheets. In this example, a total of 4 sheets including one diffusion sheet 31 for light diffusion and three prism sheets 32, 33, and 34 for increasing luminance are used. The optical sheets are stacked in this order from the light emitting surface 13 side.
[0006]
In the actual assembly process, the light guide plate 10 is housed in a holder (not shown), and then the optical sheets 30 are stacked on the light output surface 13. If dust is sandwiched between the sheets, As a result, the quality of the liquid crystal display may deteriorate.
[0007]
In order to prevent this, while turning each optical sheet after stacking, the work of blowing dust by blowing air with a blower is performed, but the thickness of each optical sheet is very thin (for example, about 0.12 mm), Not only garbage, but also the laminated optical sheets are blown away.
[0008]
Therefore, conventionally, as shown in FIG. 5, the optical sheets 31 to 34 are bonded to each other with a double-sided adhesive (adhesive) tape T so that the book is bound, and the optical sheets are stacked even if air is blown. I am trying not to move from.
[0009]
[Problems to be solved by the invention]
According to this, air can be blown between the optical sheets 31 to 34 so as to turn the page of the book, but because the four double-sided adhesive tapes T including the adhesive to the light guide plate 10 are used. Therefore, the optical sheets 30 become bulky, which is not preferable for reducing the thickness.
[0010]
Therefore, the object of the present invention is to bind a book with a double-sided adhesive tape on the same side so that the optical sheet is not blown away when dust is removed by blowing air to each optical sheet laminated on the light guide plate. Thus, in bonding, the increase in thickness associated with the use of the double-sided pressure-sensitive adhesive tape is to be suppressed.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a light guide plate disposed on the back side of a liquid crystal display panel, a light source that emits light toward a predetermined side surface of the light guide plate, and the liquid crystal display panel of the light guide plate. In the illumination device for a liquid crystal display panel, including at least four optical sheets laminated on the light emitting surface side with respect to each other, wherein the optical sheets are all bonded to each other by a double-sided adhesive tape on the same side. Each optical sheet has a tongue piece provided with the double-sided adhesive tape on the same side, and each tongue piece of the odd-numbered optical sheet and each tongue piece of the even-numbered optical sheet are laminated. It is characterized by being arranged at different positions so as not to overlap.
[0012]
According to this configuration, the double-sided pressure-sensitive adhesive tape that bonds the odd-numbered optical sheets is stored within the thickness of the even-numbered optical sheet existing between them. Because the double-sided adhesive tape that adheres to each other will fit within the thickness of the odd-numbered optical sheet existing between them, the laminated thickness of the optical sheet is almost the same as when the double-sided adhesive tape is not used It can be.
[0013]
As described above, the tongue of the lowermost optical sheet disposed on the light guide plate side among the optical sheets so that the laminated body of the optical sheets bound with the double-sided adhesive tape is not moved by the blowing air. Is preferably adhered to the light guide plate with a double-sided pressure-sensitive adhesive tape, but at this time, a recess for receiving part or all of the thickness of the double-sided pressure-sensitive adhesive tape is formed at a position corresponding to the tongue piece of the lowermost optical sheet of the light guide plate. Thus, the thickness of the double-sided pressure-sensitive adhesive tape can be absorbed.
[0014]
In addition, when the optical sheet laminated | stacked on a light-guide plate is 3 sheets of the 1st thru | or 3rd optical sheet, each tongue piece of a lower 1st optical sheet and an upper 3rd optical sheet, In addition, the double-sided adhesive tape is disposed at a position corresponding to the tongue of the first optical sheet of the light guide plate so that the tongue of the second optical sheet of the middle layer positioned therebetween does not overlap at the time of lamination. Forming a recess that accepts part or all of the thickness of the first and second optical sheets, and bonding the tongue pieces of the first and second optical sheets to different positions of the light guide plate with a double-sided adhesive tape; It is sufficient to adhere to the tongue of the first optical sheet, and the case where three optical sheets are used is also included in the present invention.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to FIGS. 1 is an exploded perspective view showing the main part of the present invention, FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1 in a state in which the optical sheets are laminated, and FIG. 3 is a view in a state in which the optical sheets are laminated. 1 is a cross-sectional view taken along line BB in FIG. The basic configuration of the lighting device may be the same as the conventional example described above.
[0016]
First, referring to FIG. 1, also in this example, the optical sheets 30 arranged on the light emitting surface 13 of the light guide plate 10 include one diffusion sheet 31 for light diffusion and one for increasing the brightness. A total of four optical sheets of three prism sheets 32 to 34 are included, but here, for convenience of explanation, the diffusion sheet 31 is used as the first optical sheet, and the lower prism sheet 32 of the three prism sheets is used. The second optical sheet, the middle prism sheet 33 is the third optical sheet, and the upper prism sheet 34 is the fourth optical sheet.
[0017]
Each of the first to fourth optical sheets 31 to 34 is provided with a tongue piece provided with a double-sided adhesive (adhesive) tape T on the same side thereof. In the present invention, the odd-numbered optical sheets are provided. The tongue pieces and the tongue pieces of the even-numbered optical sheets are arranged at different positions so as not to overlap each other during lamination.
[0018]
In this example, the odd-numbered first optical sheet 31 and the third optical sheet 33 are formed with tongue pieces 311 and 331 at the centers of the sides, respectively, and the even-numbered second optical sheet 32 and the fourth optical sheet 32. In the optical sheet 34, tongue pieces 321 and 341 are formed at two positions on the left and right sides, respectively.
[0019]
Each optical sheet 31-34 is laminated | stacked as follows, for example. First, the double-sided adhesive tape T is attached to both the front and back surfaces of the tongue piece 311 of the first optical sheet 31, and the tongue piece 311 is attached to the light guide plate 10. Next, after the second optical sheet 32 is disposed on the first optical sheet 31, the third optical sheet 33 is disposed thereon, and the tongue piece 331 of the same sheet is formed on the tongue piece 311 of the first optical sheet 31. paste.
[0020]
Next, after the double-sided adhesive tape T is attached to both tongue pieces 321 and 321 of the second optical sheet 32, the fourth optical sheet 34 is placed on the third optical sheet 33, and both tongue pieces 341 and 341 of the same sheet are placed. Is attached to both tongue pieces 321 and 321 of the second optical sheet 32. This completes the stacking operation.
[0021]
According to this, as shown in FIG. 2, the double-sided tape T that bonds between the tongue piece 311 of the first optical sheet 31 and the tongue piece 331 of the third optical sheet 33 is the first, third optical sheet 31, Thus, the thickness of the second optical sheet 32 existing between 33 is accommodated.
[0022]
As shown in FIG. 3, the double-sided tape T for bonding the tongue piece 321 of the second optical sheet 32 and the tongue piece 341 of the fourth optical sheet 34 is between the second and fourth optical sheets 32 and 34. It will be stored within the thickness of the existing third optical sheet 33.
[0023]
Therefore, the laminated thickness of the optical sheets 30 is almost the same when the double-sided pressure-sensitive adhesive tape T is used and when it is not used. That is, it can be made thinner by two double-sided pressure-sensitive adhesive tapes than the conventional example of FIG.
[0024]
More preferably, as indicated by a chain line in FIGS. 1 and 2, a recess 101 that receives a part or all of the thickness of the double-sided adhesive tape T at a position corresponding to the tongue 311 of the first optical sheet 31 of the light guide plate 10. By forming the film, the thickness can be further reduced.
[0025]
The above embodiment can be applied even when there are five optical sheets, for example. That is, when the fifth optical sheet is further used, since the fifth optical sheet is an odd number, a tongue piece is provided at the center of the side as in the first and third optical sheets 31 and 33. That's fine.
[0026]
As another example, a case where there are three optical sheets will be described. For example, if the fourth optical sheet 34 shown in the above embodiment is not used, in this case, the concave portion 101 is formed in the light guide plate 10, and the back surface of the tongue piece 311 of the first optical sheet 31. The first optical sheet 31 is disposed on the light guide plate 10 so that the double-sided adhesive tape T attached to the side (lower surface side) is dropped into the recess 101.
[0027]
Thereby, the first optical sheet 31 is arranged so that almost the entire surface thereof is in close contact with the light emitting surface 13 of the light guide plate 10. Next, for the second optical sheet 32, the double-sided adhesive tape T is attached to the back surface side (lower surface side) of the both tongue pieces 321 and 321, and the both tongue pieces 321 and 321 are attached to the light guide plate 10. And the 3rd optical sheet 33 is arrange | positioned on the 2nd optical sheet 32, The tongue piece 321 is bonded together on the tongue piece 311 of a 1st optical sheet via the double-sided adhesive tape T. FIG.
[0028]
According to this, the double-sided pressure-sensitive adhesive tape T for bonding the tongue piece 311 of the first optical sheet 31 to the light guide plate 10 is stored in the recess 101 of the light guide plate 10, and the tongue piece 321 of the second optical sheet 32 is The double-sided pressure-sensitive adhesive tape T attached to the back surface is accommodated within the thickness of the first optical sheet 31, and is a double-sided surface that bonds between the tongue piece 311 of the first optical sheet 31 and the tongue piece 331 of the third optical sheet 33. The tape T is accommodated within the thickness of the second optical sheet 32 existing between the first and third optical sheets 31 and 33.
[0029]
In the above embodiment, the odd-numbered optical sheet is provided with a tongue at the center of the side, and the even-numbered optical sheet is provided with a tongue on each side of the side. This may be reversed.
[0030]
As another modification, the odd-numbered optical sheet may be provided with a tongue on the right end side of the side, and the even-numbered optical sheet may be provided with a tongue on the left end side of the side. In short, when stacked, the odd-numbered sheets and even-numbered sheets overlap each other, but the position of each tongue may be selected so that the odd-numbered sheets and even-numbered sheets do not overlap.
[0031]
【The invention's effect】
As described above, according to the present invention, when dust is removed by blowing air to each optical sheet laminated on the light guide plate, the same side is attached to the double-sided adhesive tape so that the optical sheet is not blown away. By attaching the tongue pieces on which the double-sided pressure-sensitive adhesive tape is provided in different positions so that they do not overlap at the time of lamination with the odd-numbered optical sheet and the even-numbered optical sheet. And the increase in thickness accompanying use of a double-sided adhesive tape is suppressed, and a thinner lighting device can be provided.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a main part of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG. 1 in a state where the optical sheets are stacked.
3 is a cross-sectional view taken along the line BB in FIG. 1 in a state where the optical sheets are laminated. FIG.
FIG. 4 is a schematic side view for explaining a general configuration of a sidelight type illumination device.
FIG. 5 is a schematic cross-sectional view showing a laminated state of optical sheets conventionally performed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Light guide plate 101 Recessed part 11 Light incident surface 12 Reflector plate 13 Light output surface 20 Light source 30 Optical sheets 31 First optical sheet (diffusion sheet)
32 Second optical sheet (prism sheet)
33 Third optical sheet (prism sheet)
34 Fourth optical sheet (prism sheet)
311 321 331 341 tongue

Claims (4)

A light guide plate disposed on the back side of the liquid crystal display panel; a light source that irradiates light toward a predetermined side surface of the light guide plate; and at least four laminated on a light emitting surface side of the light guide plate with respect to the liquid crystal display panel. In an illuminating device for a liquid crystal display panel that includes a plurality of optical sheets and is bonded so that all the optical sheets are bound by a double-sided adhesive tape on the same side,
Each optical sheet has a tongue piece provided with the double-sided adhesive tape on the same side thereof, each tongue piece of the odd-numbered optical sheet and each tongue piece of the even-numbered optical sheet, An illuminating device for a liquid crystal display panel, wherein the lighting device is arranged at different positions so as not to overlap each other at the time of stacking. The lighting device for a liquid crystal display panel according to claim 1, wherein a tongue piece of a lowermost optical sheet disposed on the light guide plate side among the optical sheets is bonded to the light guide plate by the double-sided adhesive tape. The illuminating device for a liquid crystal display panel according to claim 2, wherein the light guide plate includes a recess that receives a part or all of the thickness of the double-sided pressure-sensitive adhesive tape at a position corresponding to the tongue of the lowermost optical sheet. A light guide plate disposed on the back side of the liquid crystal display panel, a light source that irradiates light toward a predetermined side surface of the light guide plate, and a first laminated on the light emitting surface side of the light guide plate with respect to the liquid crystal display panel. Or a third three optical sheets, wherein the optical sheets are bonded so that all the optical sheets are bound by a double-sided adhesive tape on the same side,
Each of the optical sheets has a tongue piece on which the double-sided adhesive tape is provided on the same side, and each of the tongue pieces of the lower first optical sheet and the upper third optical sheet, and the middle layer positioned therebetween Are arranged at different positions so as not to overlap at the time of lamination, and the light guide plate has the double-sided adhesive at a position corresponding to the tongue of the first optical sheet. A recess for receiving part or all of the thickness of the tape is formed, and the tongue pieces of the first and second optical sheets are bonded to different positions of the light guide plate by the double-sided adhesive tape, An illumination device for a liquid crystal display panel, wherein a tongue piece of an optical sheet is adhered onto the tongue piece of the first optical sheet by the double-sided adhesive tape.

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