JP4316979B2 - Liquid crystal display device and method for assembling liquid crystal display device - Google Patents

Description

  The present invention relates to a liquid crystal display device and a liquid crystal display device assembly method, and more particularly to a liquid crystal display device including a backlight having a light source disposed on a side end surface of a light guide plate and a method for assembling the liquid crystal display device.

  In a conventional liquid crystal display device, a backlight is disposed on the back surface of a liquid crystal panel, and the backlight makes light emitted from an LED light source incident on a side end surface of the light guide plate, and the propagated light is on the surface side of the light guide plate. A surface light source is configured by emitting the light from a light source through a prism sheet or the like, and the entire back surface of the liquid crystal panel is irradiated. Specifically, as shown in FIG. 11, the light guide plate 2 made of a transparent plate is dropped in a state where the reflector 5 is laid in the concave portion of the case 1 having the bottom wall 1 a and the side walls 1 b and 1 c, and the light guide plate 2 side. The LED 4 mounted on the flexible printed circuit board 3 is fitted into a gap generated between the light incident surface 2a which is an end surface and the side wall 1c.

Since the flexible printed circuit board 3 to which the LED 4 is fixed is fixed to the side wall 1c of the case 1, there is a variation of the distance L1 due to dimensional tolerance or the like between the LEC 4 and the light incident surface 2a of the light guide plate 2. This distance L1 is related to the surface brightness of the backlight, and if the distance L1 is long, the light emitted from the LED 4 leaks to the outside, the light incident efficiency to the light guide plate 2 decreases, and a predetermined brightness cannot be obtained. There is. That is, as the distance L1 is shorter, light emitted from the LED 4 can be effectively incident on the light incident surface 2a of the light guide plate 2.
However, if the distance L1 is designed to be narrow, it is difficult to fit the LED 4 mounted on the flexible printed circuit board 3 into the gap between the light incident surface 2a of the light guide plate 2 and the side wall 1c of the case 1, and the work efficiency is greatly reduced. Problems occur.

  In Japanese Patent Laid-Open No. 2002-156632, a liquid crystal display device as shown in FIGS. 12A and 12B is proposed, and the inner wall surface of the mold frame 5 positioned on the opposite side of the light incident surface 6a of the light guide plate 6 is proposed. The claw 5a having elasticity is formed on the light guide plate 6 and the light guide plate 6 is pressed and held on the LED 7 side by the claw 5a, so that the gap between the light incident surface 6a of the light guide plate 6 and the LED 7 is made constant.

However, since the light guide plate 6 dropped into the concave portion of the mold frame 5 is moved to the light incident surface 6a side by the claw 5a, the gap between the light incident surface 6b of the light guide plate 6 and the inner wall surface of the mold frame 5 is increased. There arises a problem that the gap 8 is generated and light leaks, and the reflection efficiency on the side of the light incident surface 6b is deteriorated.
Further, since the light guide plate 6 is pressed toward the light incident surface 6a side by the claw 5a, in order to prevent a large stress from being applied to the LED 7, a recessed portion 5b for LED installation is provided as shown in FIG. It must be provided on the side wall of the mold frame 5. In this case, in order to form the recess 5b in the mold frame 5, the thickness of the side wall of the mold frame 5 must be increased, and the strength of the mold frame 5 is also reduced because the recess 5b is locally thin. There is a problem.

  In JP-A-2002-287138, by providing a positioning part such as a step in a case that accommodates the light guide plate, the distance between the light incident surface of the light guide plate and the LED is maintained at a predetermined interval, and brightness and display unevenness are maintained. To prevent adverse effects. However, the reflection efficiency on the side opposite to the light incident surface of the light guide plate is not considered, and if the distance between the light guide plate and the LED is set very small, the light incident on the light guide plate The problem of difficulty in fitting the LED into the gap between the surface and the case has not been solved.

Furthermore, in Japanese Patent Application Laid-Open No. 2003-156739, a reflection sheet is integrally provided on the lower surface and side surface of the light guide plate via an adhesive, and the cutout portion of the light guide plate is used as an LED arrangement space without using a frame. Yes. However, since it is necessary to attach a plurality of reflection sheets to the light guide plate with an adhesive, man-hours are increased and work efficiency is lowered. In order to prevent the LEDs from moving, a flexible printed circuit board on which LEDs are mounted is used. There is a problem in that the work efficiency is lowered because it is necessary to fix the light guide plate to the light guide plate with an adhesive.
JP 2002-156632 A JP 2002-287138 A Japanese Patent Laid-Open No. 2003-156739

  The present invention has been made in view of the above problems, and has achieved the conflicting demands of improving the incident efficiency to the light guide plate and improving the light source mounting work efficiency, and reflecting on the light incident surface of the light guide plate. The challenge is to improve efficiency.

In order to solve the above-described problems, the present invention includes a backlight on the back side of the liquid crystal panel, and the backlight has a light guide plate fitted inside the outer peripheral frame of the case and is an input side surface of the light guide plate. In the liquid crystal display device in which the light source is arranged facing the light surface,
Providing a reflective material to be inserted into the gap between the light incident surface opposite to the light incident surface of the light guide plate and the outer peripheral frame of the case;
When the light source is inserted and disposed in the gap between the light incident surface of the light guide plate and the outer peripheral frame of the case, the gap is widened with the reflector not inserted, and after the light source is disposed, the light guide is inserted. A liquid crystal display device is provided in which the light plate is moved close to the light source side and the reflective material is inserted into the gap.

With the above configuration, when assembling the light source, it is possible to easily fit the light source into the gap by expanding the gap between the outer peripheral frame of the case and the light incident surface of the light guide plate when the reflector is not inserted. The efficiency of the light source assembly work can be improved. After the light source is assembled, the light guide plate is moved closer to the light source side by inserting the reflective material into the gap between the light incident surface of the light guide plate and the outer peripheral frame of the light guide plate. It is possible to improve the incident efficiency of the light emitted from the light source to the light guide plate while keeping the clearance between them constant. In addition, since the reflecting material is placed along the light incident surface of the light guide plate, the light propagated through the light guide plate does not leak from the light incident surface, and the reflection efficiency can be improved.
Therefore, it is possible to achieve both the improvement in the incidence efficiency to the light guide plate and the improvement in the efficiency of the light source mounting operation, and the reflection efficiency on the light incident surface of the light guide plate is also improved.

Provided integrally with the case is a hook piece having flexibility that can be projected and retracted in the gap between the light incident surface opposite to the light incident surface of the light guide plate and the outer peripheral frame of the case,
When the light source is inserted and disposed in the gap between the light incident surface of the light guide plate and the outer peripheral frame of the case, the hook piece is positioned outward from the gap, and after the light source is placed, the hook piece is The light guide plate is moved close to the light source side by moving the gap and pressing the light incident surface of the light guide plate.

  With the above configuration, when the light source is assembled, the light incident surface of the light guide plate is not held by the hook piece by placing the lower surface of the light guide plate on the hook piece and positioning the hook piece outward. Thus, the gap between the outer peripheral frame of the case and the light incident surface of the light guide plate can be widened to easily fit the light source into the gap. On the other hand, after the light source is assembled, the light guide plate is moved to the light source side by pressing and holding the anti-light entrance surface of the light guide plate by causing the hook piece to protrude and retract in the gap between the light entrance surface of the light guide plate and the outer peripheral frame of the case. By moving close to each other, the clearance between the light incident surface of the light guide plate and the light source can be kept narrow and constant, and the incident efficiency of the light emitted from the light source onto the light guide plate can be improved. In addition, since the light incident surface of the light guide plate is held by the hook piece and the gap between the light incident surface of the light guide plate and the case outer peripheral frame is widened, the work of inserting the reflective material into the gap There is an advantage that becomes easy to do.

  In addition, the hook piece cuts a part of the case bottom wall located on the back surface of the light guide plate to form a bent portion having a free end, and a protrusion protruding from the tip of the bent portion to the surface side is provided. Therefore, it is preferable to provide it integrally with the case.

  Note that the liquid crystal panel used in the present invention is not limited to the simple matrix type, and may be an active matrix type liquid crystal panel such as a thin film transistor or other various types of liquid crystal panels. Further, the size of the liquid crystal panel is not limited to a small size such as a mobile phone or a portable information terminal, but can be applied to a relatively large size liquid crystal panel.

In addition, the present invention secondly includes a backlight on the back side of the liquid crystal panel, and the backlight has a light guide plate fitted in the outer peripheral frame of the case and a light incident surface that is a side end surface of the light guide plate. In the assembling method of the liquid crystal display device in which the light source is arranged opposite to the
The light source is inserted and disposed in the gap as the gap between the light incident surface of the light guide plate and the case outer peripheral frame is expanded while the light guide plate is fitted into the case.
Next, the light guide plate is moved close to the light source side, and the gap between the light incident surface opposite to the light incident surface of the light guide plate and the outer peripheral frame of the case is widened, and a band-like reflection is formed in the gap. A method of assembling a liquid crystal display device characterized by inserting a material is also provided.

  As is clear from the above description, according to the present invention, when the light source is assembled, the light reflector is not inserted and the gap between the light incident surface of the light guide plate and the case outer peripheral frame is widened so that the light source can be easily fitted. While the work efficiency can be improved, the light reflector is inserted into the gap between the light incident surface of the light guide plate and the outer frame of the case after the light source is assembled, and the light guide plate is moved closer to the light source side. Incidence efficiency to the light guide plate can be improved. In addition, since the reflecting material is provided on the light incident surface of the light guide plate, the light propagated through the light guide plate does not leak from the light incident surface, and the reflection efficiency can be improved.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an exploded perspective view of a liquid crystal display device 10 according to the first embodiment. The liquid crystal display device 10 includes a liquid crystal panel 18 and a backlight 24 serving as a lighting device disposed on the back side of the liquid crystal panel 18, and the liquid crystal panel 18 and the backlight 24 are held and fixed by a bezel (not shown). ing. The liquid crystal panel 18 is provided with a pair of substrates (not shown) that sandwich the liquid crystal and a drive circuit (not shown) for controlling the alignment state of the liquid crystal.

  The backlight 24 is made of a resin and is integrally formed with a case 11 having a recess 22, a reflector 14 laid in the recess 22 of the case 11, and a rectangular transparent body made of a polycarbonate resin molded product disposed on the reflector 14 A light guide plate 15, which is a plate, an LED (light source) 13 disposed between the light incident surface 15 a of the light guide plate 15 and the case 11, a flexible printed circuit board 12 on which a plurality of LEDs 13 are mounted, and the light guide plate 15. A reflecting sheet (reflecting material) 23 disposed on the light incident surface 15 b side, and first and second prism sheets 16 and 17 stacked orthogonally on the light guide plate 15 are provided. The case 11 is not limited to resin.

The case 11 has a recess 22 formed by providing a high-profile side wall 20 on three sides of the periphery of the rectangular bottom wall 19 and providing a low-profile side wall 21 on the other side to form an outer peripheral frame.
The reflection sheet 23 has a strip shape that is substantially the same shape as the light incident surface 15 b of the light guide plate 15, and has a thickness that can be inserted into the gap between the light incident surface 15 b of the light guide plate 15 and the side wall 20 of the case 11. Specifically, the thickness is 0.05 mm to 1.0 mm. The material of the reflection sheet 23 is not particularly limited, and the reflection surface is preferably white reflection, mirror reflection such as silver or aluminum.

The reflection plate 14 is installed under the light guide plate 15 in order to increase the use efficiency of light incident from the light incident surface 15 a of the light guide plate 15, but the bottom wall 19 of the case 11 is substituted for the single reflection plate 14. A reflective layer may be formed by vapor deposition of aluminum.
The first and second prism sheets 16 and 17 are stacked so that the prism grooves are crossed. However, if unevenness or the like is seen on the light emitting surface, a diffusion plate may be further used.

Next, the assembly procedure of the backlight 24 will be described.
First, as shown in FIG. 2, the light guide plate 15 is dropped with the reflection plate 14 laid in the recess 22 of the case 11, and the light incident surface 15 b of the light guide plate 15 is moved toward the side wall 20, thereby The gap between the light incident surface 15a and the low-profile side wall 21 is widened, and the LED 13 mounted on the flexible printed circuit board 12 is fitted and assembled into the widened gap. Thus, since the clearance S between the light incident surface 15a of the light guide plate 15 and the LED 13 can be made large as the distance d1, the assembly work of the LED 13 can be easily performed, and the workability is improved. In the present embodiment, the distance d1 of the clearance S is set to 0.1 mm or more and 1 mm or less.

Next, as shown in FIG. 3, the light guide plate 15 is moved closer to the LED 13 side to narrow the gap between the light incident surface 15 a of the light guide plate 15 and the LED 13, that is, the light incident surface 15 b and the side wall of the light guide plate 15. The gap with 20 is widened, and the reflection sheet 23 is inserted into the widened gap.
In this state, since the clearance distance d2 between the light incident surface 15a of the light guide plate 15 and the LED 13 is narrowed to a constant interval of 0 mm or more and 0.1 mm or less, the incident efficiency of the light emitted from the LED 13 to the light guide plate 15 is reduced. Can be improved. Since the LED 13 is sandwiched between the light incident surface 15 a of the light guide plate 15 and the side wall 21 of the case 11, the flexible printed circuit board 12 on which the LED 13 is mounted need not be fixed to the case 11.

With the above configuration, the reflection sheet 23 is provided on the anti-incident light surface 15b of the light guide plate 15. Therefore, the light propagated through the light guide plate 15 does not leak from the anti-incident light surface 15b, and the reflection efficiency can be improved. It becomes.
The reflection sheet 23 may be provided not only on the light incident surface 15 b but also on a side end surface orthogonal to the light incident surface 15 a of the light guide plate 15.

4 and 9 show a second embodiment.
The difference from the first embodiment is that a hook piece 46 is provided on the case 31.

As shown in FIGS. 4 and 5, the case 31 is provided with a high-side wall 40 on the three sides of the rectangular bottom wall 42 and a low-side wall 41 on the other side to form an outer peripheral frame. A concave portion 42 is formed, and a U-shaped slit 45 is cut into a bottom wall 42 in contact with the side wall 40 located on the opposite side of the low-profile side wall 41 to provide a flexible hook piece 46.
The hook piece 46 includes a bent portion 46a surrounded by the slit 45 and a protruding portion 46b that protrudes upward from the free end of the bent portion 46a. By pushing down the protruding portion 46b from above, the entire hook piece 46 is It bends to the back side.

  As shown in FIG. 9, the reflection sheet 43 has a strip shape that is substantially the same shape as the light incident surface 15 b of the light guide plate 15, and the thickness thereof is between the light incident surface 15 b of the light guide plate 15 and the side wall 20 of the case 11. A notch 43a is provided at the lower end of the position corresponding to the protrusion 46b of the hook piece 46, with a thickness that allows insertion into the gap.

  As shown in FIG. 6, the light guide plate 15 is dropped with the reflector 14 laid in the recess 45 of the case 31, and the bottom surface of the light guide plate 15 is placed on the protrusion 46 b of the hook piece 46, so that the hook piece 46 is placed on the back side. To bend. In this state, since the light guide plate 15 is free, the gap between the light incident surface 46a and the low-profile side wall 41 can be widened, and the LED 13 mounted on the flexible printed circuit board 12 is fitted into the widened gap. Assemble. In the present embodiment, the distance d1 of the clearance S between the light incident surface 15a of the light guide plate 15 and the LED 13 is 0.2 mm or more and 2 mm or less.

  Then, as shown in FIG. 7, the hook piece 46 is elastically restored while sliding the light guide plate 15 toward the LED 13, so that the anti-light incident surface 15 b facing the light incident surface 15 a of the light guide plate 15 becomes the hook piece 46. Pressed and held by the protrusion 46b, the clearance distance d2 between the light incident surface 15a of the light guide plate 15 and the LED 13 is narrowed to a constant interval of 0 mm or more and 0.1 mm or less.

  Next, as shown in FIG. 8, the reflective sheet 43 is inserted into the gap between the case side wall 31 and the anti-incident light surface 15 b of the light guide plate 15, and the anti-incident light surface 15 b is covered with the reflective sheet 43 and the reflective sheet 43 is notched. The portion 43a is positioned on the protrusion 46b of the hook piece 46 so that the protrusion 46b and the reflection sheet 43 do not interfere with each other. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

With the above configuration, the gap between the case side wall 31 and the anti-light-incident surface 15b of the light guide plate 15 can be maintained by the hook piece 46. Therefore, when the reflective sheet 43 is inserted, A person does not need to hold the light guide plate 15 and can improve the assembling workability of the reflection sheet 43.
Note that the position of the hook piece 46 is not limited to that shown in FIG. 4, and the hook piece 46 may be provided at a position where the side end surface orthogonal to the light incident surface 15 a of the light guide plate 15 is pressed. The number of hook pieces 23 may be any number.

FIG. 10 shows a third embodiment.
The difference from the first embodiment is that a tapered surface 68 a and a tapered portion 60 a are provided on the reflector 63 and the side wall 60 of the case 51.

The reflective material 63 is formed by sticking a reflective sheet 67 on one surface side of a resin spacer 68, and the spacer 68 narrows the width so that the surface opposite to the surface on which the reflective sheet 67 is pasted is directed downward. The tapered surface 68a is used.
The case 51 includes a tapered portion 60a that protrudes inward toward the inner surface of the side wall 60 that faces the light-incident surface 15b of the light guide plate 15.

  With the above configuration, when the reflecting material 63 is inserted in the direction of the arrow in the figure, the tapered surface 68a of the reflecting material 63 is guided to the tapered portion 60a of the side wall 60, and therefore, between the anti-light-incident surface 15b and the side wall 60. This makes it easier to insert the reflector 63 into the gap and improves the assembly workability. In the present embodiment, the reflecting material 63 is configured by pasting a separate body of the reflecting sheet 67 and the spacer 68. However, the same taper as described above may be provided on an integrated product of reflective materials. Needless to say, it is good.

It is a disassembled perspective view which shows the liquid crystal display device of 1st Embodiment of this invention. It is sectional drawing which shows the time of attachment of LED. It is sectional drawing of the state which assembled | attached the reflective sheet. It is a top view of the case of 2nd Embodiment. It is the sectional view on the AA line of FIG. It is a top view of the state which assembled the light-guide plate and LED. It is sectional drawing of the state which returned the hook piece. It is sectional drawing of the state which assembled | attached the reflective sheet. It is a perspective view of a reflective sheet. It is sectional drawing which shows 3rd Embodiment. It is sectional drawing which shows a prior art example. (A) is a top view of another conventional example, and (B) is a cross-sectional view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal display device 11 Case 12 Flexible printed circuit board 13 LED (light source)
14 Reflecting plate 15 Light guide plate 15a Light incident surface 15b Anti-light incident surface 16 First prism sheet 17 Second prism sheet 18 Liquid crystal panel 20, 21 Side wall (outer frame)
23 Reflective sheet (reflective material)
24 Backlight 46 Hook piece S Clearance

Claims (3)

A backlight on the back side of the liquid crystal panel, the backlight includes a rectangular bottom wall, the light guide plate in the inner portion of the case that having a peripheral frame along the four sides of the bottom wall along said outer peripheral frame with fitted Te, in a liquid crystal display device the light source is disposed between the light incident surface is a side end surface of the inner surface and the light guide plate of one side of the peripheral frame,
The length between the light incident surface of the light guide plate and the opposite light incident surface opposite to the light incident surface with respect to the dimension from the inner surface of the outer peripheral frame opposite to the light source arrangement side of the case to the light source. with dimensions are small, the liquid crystal display device reflecting material in the gap between the counter-incident surface of the upper Kishirube light plate and the outer frame of the case is characterized that you have been inserted. Provided integrally with the case is a hook piece having flexibility that can be projected and retracted in the gap between the light incident surface opposite to the light incident surface of the light guide plate and the outer peripheral frame of the case,
The hook piece has a shape in which a part of the bottom wall is cut into a U-shape and a protrusion protruding above the tip is provided,
The anti-light incident surface of the light guide plate and the gap between the outer peripheral frame of the case, the liquid crystal display device according to claim 1, wherein the hook piece at the bottom of the reflective material that has been inserted. A liquid crystal panel and a backlight on the back side of the liquid crystal panel are provided, and the liquid crystal panel and the backlight are held and fixed by a bezel,
The backlight includes a rectangular bottom wall, the inner portion of the case that having a peripheral frame along the four sides of the bottom wall, the reflective plate from the bottom wall side, light guide plate, with sequentially arranged a prism sheet In the assembling method of the liquid crystal display device in which the light source is disposed between the light incident surface which is the side end surface of the light guide plate and the outer peripheral frame of the case ,
The light guide plate is fitted along the outer peripheral frame of the case, and a state of expanding the gap between the light incident surface and the case outer peripheral frame of the light guide plate,
The light source insertion placed the gap,
Then, the light guide plate in proximity moved to the light source side, and a state of expanding the gap between the outer peripheral frame opposite to the counter-incident surface and the case of the light incident surface of the light guide plate, strip into the gap A method for assembling a liquid crystal display device, comprising inserting a reflective material.

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