JP2006208466A - Direct backlight - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight for preventing the deformation of a diffusing plate due to heat generation of a light source. <P>SOLUTION: The direct-type backlight 10 comprises fluorescent lamps 1 arranged behind a liquid crystal panel of a liquid crystal display device and juxtaposed on a bottom 11a in a flat lamp house LH opened at the side of a liquid crystal panel, and having the diffusing plate 16 arranged by covering an opening part of the lamp house LH. The fluorescent lamp 1 includes a diffusing plate restraining pin 14 for connecting the bottom part 11a and the diffusing plate 16 in the lamp house LH except for an arrangement part, and the diffusing plate 16 is restrained from deflecting to the side of the liquid crystal panel by engaging a stopper head part 14d of the diffusing plate restraining pin 14 with a hole 18a to be engaged of the diffusing plate 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a direct type backlight, and more particularly to a backlight that is disposed behind a liquid crystal panel of a liquid crystal display device and has a diffusion plate disposed on the front side of a light source.

In recent years, display devices used for OA equipment have been reduced in weight, thickness, and screen size. In general households, demand for large-screen televisions that can provide a greater sense of realism is rapidly expanding, and it is important to develop a flat panel display with a large area that can be reduced in thickness and weight. For this reason, development of larger screens is also being promoted in display devices such as liquid crystal display devices, plasma display devices, EL (electro luminescent) display devices, and LED (light emitting display) devices.
Among these, liquid crystal display devices have advantages such as being able to be made thinner and having lower power consumption than other display devices, and thus have been widely used in various fields in recent years.

  In general, large liquid crystal display devices employ a so-called direct type structure in which a plurality of fluorescent lamps are arranged in a lamp house and a backlight that forms a planar light source is installed directly under the liquid crystal panel. ing. In such a liquid crystal display device, in general, the fluorescent lamp is installed in a lamp house provided with a reflector so that the shape of the fluorescent lamp is not visually recognized through the liquid crystal panel, and the light of the fluorescent lamp effectively irradiates the liquid crystal panel. It has a structure in which a diffuser plate is disposed on the lamp house and a liquid crystal panel is installed thereon.

In such a direct type backlight unit, when the liquid crystal display device is enlarged, its weight naturally increases, and the diffusion plate is heated by the heat dissipated from the fluorescent lamp, and the diffusion plate is bent and deformed. To do. In general, a milky white acrylic plate is used as the diffusion plate. However, the acrylic plate has high hygroscopicity, absorbs moisture when the humidity is high, expands its volume, dehydrates when dried, shrinks its volume, and deforms.
As described above, when the diffusion plate is bent and deformed, uneven luminance occurs in the liquid crystal display device. Therefore, the technique shown in FIG. 12 is proposed by Japanese Patent Laid-Open No. 10-326517 (Patent Document 1). In this technique, a fluorescent lamp 1 is arranged at the bottom of a flat lamp house 3 having an upper opening, and a backlight 10 having a diffuser plate 2 disposed in a closed manner at the opening of the lamp house 3 is used. The backlight which arrange | positions the spacer pin 4 in the bottom part of this is proposed.

However, according to this prior art, since the tip of the spacer pin 4 is only in contact with the diffusion plate 2, it is possible to prevent the diffusion plate 2 from bending to the fluorescent lamp 1 side (convex downward in the figure), As shown in FIG. 13, it is not possible to prevent the liquid crystal panel from being bent toward the liquid crystal panel (projecting upward in the drawing), and the central portion of the diffusion plate 2 may be close to the liquid crystal panel, and pressure may be applied to the liquid crystal panel. For this reason, unevenness may occur in the amount of light incident on the liquid crystal panel, or interference fringes may be generated by pressing the liquid crystal panel.
JP-A-10-326517

  The present invention has been made in view of the above problems, and an object of the present invention is to prevent the diffusion plate from being deformed toward the liquid crystal panel and causing display unevenness.

In order to solve the above-mentioned problem, the present invention is arranged behind the liquid crystal panel of the liquid crystal display device, and the light source is arranged at a distance from the bottom of a flat lamp house opened to the liquid crystal panel side. In a direct type backlight having a diffusion plate disposed to cover the opening of the lamp house,
Diffusing plate restraining means for connecting the diffuser plate to the bottom of the lamp house other than the location of the light source and the diffuser plate is provided, and the diffusing plate restraining means restrains the diffuser plate from bending at least toward the liquid crystal panel. A direct type backlight characterized by having a configuration is provided.

  With this configuration, since the movement of the diffusion plate toward the liquid crystal panel is restricted, it is possible to prevent the liquid crystal panel from being pressed by deformation due to its own weight, humidity, or thermal expansion. Unevenness can be prevented. The diffusion plate restraining means can be effectively prevented from being deformed by being provided near the center of the diffusion plate having a large degree of curvature.

The diffusion plate restraining means is a diffusion plate restraining pin standing on the bottom of the lamp house and having a locking portion on the tip side, and a locked portion provided at a position corresponding to the locking portion of the diffusion plate. And
It is preferable that the locking portion is engaged with the locked portion to restrain the movement in the direction perpendicular to the plate surface of the diffusion plate.

Alternatively, the diffusion plate restraining means includes a diffusion plate restraining pin that is suspended from the diffusion plate and has a locking portion on the tip side, and a locked state provided at a position corresponding to the locking portion at the bottom of the lamp house. With
It is good also as a structure which the said latching | locking part engages with the said to-be-latched part, and restrains a perpendicular | vertical movement with respect to the plate | board surface of the said diffuser plate.

  With this configuration, the diffusion plate restraining pin can be formed integrally with the lamp house, which contributes to a reduction in the number of parts. In addition, since the locking portion of the diffusion plate restraining pin is connected to the locked portion of the diffusion plate, the lamp house and the diffusion plate can be handled as separate bodies, and the handleability is improved. .

Provided with a large-diameter locking head at the tip of the shaft portion of the diffusion plate restraining pin to be the locking portion, the locked portion is a locked hole,
The locking head is forcibly inserted into the locked hole, the shaft portion is fitted into the locked hole, and the locking head is brought into contact with the peripheral edge of the locked hole. It is preferable to stop.

  With the above configuration, since the diffusion plate is placed on the lamp house and at the same time, the locked holes can be locked to each other simply by press-fitting the locked holes into the locking heads. In addition, workability can be improved.

It is preferable that the diffusion plate restraining pin is provided with a support portion that comes into contact with the periphery of the locked hole on the side opposite to the locking head.
With the above-described configuration, it is possible to simultaneously prevent the diffusion plate from being bent toward the light source by the support portion, which contributes to reduction in display unevenness.

A plurality of the diffusion plate restraining pins are provided, and one of the diffusion plate restraining pins is for positioning, and the shaft portion is closely fitted to the locked hole to restrain the movement in the surface direction of the diffusion plate. While
The remaining diffusion plate restraining pins have a clearance for absorbing thermal expansion in the surface direction of the diffusion plate between the shaft portion and the locked hole.

  With the above configuration, the first diffusion plate restraining pin can be used for positioning the diffusion plate, and a clearance is provided between the shaft portion of the second and subsequent diffusion plate restraining pins and the locked hole. Therefore, even if the diffusion plate is thermally expanded, the diffusion plate restraining pin does not restrain the diffusion plate in the surface direction, and the diffusion plate can be prevented from being bent. In addition, it is preferable that the clearance is provided so as to expand in the arrangement direction of the plurality of locked holes, and is set to be larger than the amount of change due to thermal expansion of the length between the diffusion plate restraining pins.

  As is clear from the above description, according to the present invention, since the movement of the diffusion plate in the direction toward the liquid crystal panel is restricted, the liquid crystal panel is pressed by deformation or bending due to humidity or thermal expansion of the diffusion plate. Can be prevented, and display unevenness of the liquid crystal display device can be prevented.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an exploded perspective view of a direct type backlight 10 according to the first embodiment.
The backlight 10 is arranged behind a liquid crystal panel (not shown) to constitute a liquid crystal display device, and is provided on the upper surface side of the lower frame 11 having a concave cross section that opens to the liquid crystal panel side (upper side in the drawing). A lamp house LH is formed by accommodating a reflecting plate 12 having a concave cross section, and a fluorescent lamp 1 as a linear light source is arranged in the lamp house LH, and both ends of the fluorescent lamp 1 are positioned by a light source holding member 13. is doing. A resin diffusion plate 16 is disposed so as to cover the upper surface opening of the lamp house LH, and is closed by a frame-shaped upper frame 17. That is, the direct light from the fluorescent lamp 1 or the light reflected by the reflection plate 12 enters the diffusion plate 16 from the back, and the light transmitted and diffused by the diffusion plate 16 is emitted to a liquid crystal panel (not shown). Thus, the liquid crystal display is performed.

A pair of diffusion plate restraining pins 14 are erected in the vicinity of the center at the bottom of the lamp house LH other than where the fluorescent lamp 1 is disposed.
As shown in FIG. 4, the diffusion plate restraining pin 14 is not reduced in diameter on the base part 14a, the column part 14b protruding while reducing the diameter upward from the base part 14a, and the distal end side of the column part 14b. A shaft portion 14c having the same diameter and an umbrella-shaped locking head portion 14d having a diameter larger than that of the shaft portion 14c bulging at the tip of the shaft portion 14c are provided, and a notch portion 14e is provided at the lower peripheral edge of the base portion 14a. Provided.
A hole 12a is formed in a portion of the reflector 12 where the diffuser plate restraining pin 14 is disposed, and the lower end surface of the diffuser plate restraining pin 14 is bonded and fixed to the bottom portion 11a of the lower frame 11 to restrain the diffuser plate. The periphery of the hole 12a is held by the notch portion 14e of the pin 14. The diffusion plate restraining pin 14 may be formed integrally with the lower frame 11 or the reflection plate 12.

The diffusion plate 16 has mounting holes 18 and 19 at positions corresponding to the diffusion plate restraining pins 14. The mounting hole 18 is larger in diameter than the shaft portion 14c and smaller in diameter than the locking head 14d, and the diameter of the mounting hole 18 is increased stepwise above the locked hole 18a. Is also provided with a large step 18b.
That is, the locking head portion 14d is forcibly inserted into the locked hole 18a from the back side, the shaft portion 14c is fitted into the locked hole 18a, and the locking head portion 14d is inserted into the locked hole at the step portion 18b. It can be locked by bringing it into contact with the peripheral edge of the front surface of 18a.

As shown in FIG. 5, one of the locked holes 18a has a rectangular shape that is substantially closely fitted to the shaft portion 14c of the diffuser plate restraining pin 14, but the other locked hole 19a is formed of a diffuser plate restraining pin. It is made into the rectangular shape fitted in the state which provided the clearance C largely in the X direction with respect to 14 axial parts 14c.
That is, the X-direction and Y-direction clearances between the shaft portion 14c of the diffusion plate restraining pin 14 and the locked hole 18a are also positioned in the surface direction as a minimum size for absorbing manufacturing errors. The other diffusion plate restraining pin 14 has a minimum clearance for absorbing manufacturing errors in the Y direction, but the length Lx between the locked holes 18a and 19a of the diffusion plate 16 in the X direction. The clearance C is increased by the amount of thermal expansion.
The width of the clearance C is determined so as to satisfy the following formula 1.
[Formula 1]
Clearance width ≥ Linear expansion coefficient of diffuser plate x Lx x temperature difference

With the above configuration, the movement (in the direction of the arrow in FIG. 4) of the diffusion plate 16 deforming toward the liquid crystal panel (not shown) side (convex upward) is restrained by the diffusion plate restraining pin 14. It is possible to prevent the diffusion plate 16 due to thermal expansion from being bent toward the liquid crystal panel and pressing the liquid crystal panel, and display unevenness of the liquid crystal display device can be prevented. Since the diffusion plate restraining pin 14 is provided in the vicinity of the center of the diffusion plate 16 where the degree of curvature is large, the diffusion plate 16 can be effectively prevented from being deformed. Further, since the clearance C in the X direction is provided in the locked hole 19a, the diffusion plate restraining pin 14 does not restrain the diffusion plate 16 in the surface direction even if the diffusion plate 16 is thermally expanded, and the diffusion plate 16 is distorted. Can also be prevented.
In addition, it is preferable to provide the diffusion plate restraining pin 14 and the spacer pin 4 shown in FIG. The present invention is particularly suitable for a direct type backlight having a large-area diffusion plate for a large-sized liquid crystal display device, but needless to say, it is effective even for a medium-sized liquid crystal display device.

FIG. 6 shows a second embodiment.
The difference from the first embodiment is that only one diffusion plate restraining pin 14 having the same structure as that of the first embodiment is provided at the center. In this case, the locked hole 28a of the diffuser plate 26 is provided in the approximate center of the diffuser plate 26, and has a rectangular shape that is substantially tightly fitted to the shaft portion 14c of the diffuser plate restraining pin 14, and is also positioned in the surface direction. ing. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

FIG. 7 shows a third embodiment.
The difference from the first embodiment is that one diffusion plate restraining pin 14 is added in the Y direction and a total of three are arranged. In this case, the diffusion plate 36 is provided with three locked holes 38a to 40a corresponding to the diffusion plate restraining pins 14, respectively.
The first locked hole 38a has a shape that is closely fitted to the shaft portion 14c of the diffusion plate restraining pin 14c for positioning. The second locked hole 39a is provided with a clearance C corresponding to the thermal expansion of the length Lx between the locked holes 38a and 39a of the diffusion plate 36 in the X direction. The third locked hole 40a has a clearance C corresponding to the thermal expansion of the length Ly between the locked holes 38a and 40a of the diffusion plate 36 in the Y direction. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

FIG. 8 shows a fourth embodiment.
The difference from the first embodiment is that a total of five diffuser plate restraining pins 14 are arranged in a cross shape. In this case, the diffusion plate 46 is provided with five locked holes 48a to 52a corresponding to the diffusion plate restraining pins 14, respectively.
The locked hole 48a at the center has a shape that is substantially closely fitted to the shaft portion 14c of the diffusion plate restraining pin 14c for positioning. The left and right locked holes 49a and 51a in the X direction have a clearance C corresponding to the thermal expansion of the length Lx between the locked holes 38a and 39a of the diffusion plate 36 in the X direction. The upper and lower locked holes 50a and 52a in the Y direction are provided with a clearance C corresponding to the thermal expansion of the length Ly between the locked holes 38a and 40a of the diffusion plate 36 in the Y direction. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

FIG. 9 shows a fifth embodiment.
In the present embodiment, a locked hole 57 c is provided at the tip of the diffusion plate restraining pin 57, and a locking head portion 56 b is provided in the diffusion plate 56.
Specifically, the diffusion plate restraining pin 57 includes a base portion 57a, a column portion 57b that protrudes from the base portion 57a while being reduced in diameter upward, and a locked hole 57c that is formed in the distal end surface of the column portion 57b. And a receiving portion 57d having a large-diameter space communicating with the lower portion of the locked hole 57a, and a notch 57e is provided at the lower peripheral edge of the base portion 57a.
The diffusion plate 56 has a shaft portion 56a protruding from a position corresponding to the diffusion plate restraining pin 57, and is provided with a large-diameter locking head portion 56b at the tip of the shaft portion 56a.
That is, the locking head 56b of the diffusion plate 56 is forcibly inserted through the locked hole 57c of the diffusion plate restraining pin 57, the shaft portion 56a is fitted into the locked hole 57c, and the locking head 56b is accommodated. The portion 57d can be locked by contacting the peripheral edge of the back surface of the locked hole 57c. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

FIG. 10 shows a sixth embodiment.
The difference from the first embodiment is that the diffusion plate restraining pin 64 is provided with a support portion 64f that abuts the lower surface side periphery of the locked hole 16a of the diffusion plate 16.
The diffusion plate restraining pin 64 includes a base portion 64a, a column portion 64b that protrudes from the base portion 64a while reducing the diameter upward, a support portion 64f that protrudes like a bowl on the tip side of the column portion 64b, and a support portion. A shaft portion 64c that protrudes upward from 64f with the same diameter and an umbrella-shaped locking head portion 64d that bulges at the tip of the shaft portion 64c are provided, and a notch portion 64e is provided at the lower edge of the base portion 64a. ing.
When the locking head 64d is inserted into the locked hole 16a from the back side and the shaft portion 64c is fitted into the locked hole 16a, the locking head 64d is located on the front side of the locked hole 16a at the stepped portion 16b. While being locked to the periphery, the support portion 64f is brought into contact with the back side peripheral edge of the locked hole 16a.
With this configuration, the diffusion plate 16 can be prevented from being bent toward the fluorescent lamp 1 by the support portion 64f at the same time, so that deformation in both vertical directions can be constrained, contributing to reduction in display unevenness. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

FIG. 11 shows a seventh embodiment.
In this embodiment, a diffusion plate restraining pin 66a is integrally suspended from the diffusion plate 66, and a locked hole 73c is provided in the lower frame 73 constituting the lamp house.
The diffusion plate restraining pin 66a includes a column portion 66a-1 protruding from the lower surface of the diffusion plate 66, a shaft portion 66a-2 having a reduced diameter on the distal end side of the column portion 66a-1, and a distal end side of the shaft portion 66a-2. And a locking head 66a-3 having a larger diameter.
The lower frame 73 includes a bulging portion 73a, a part of which bulges integrally in a convex shape, and a locked hole 73c formed in the distal end surface 73b of the bulging portion 73a.
That is, the locking head 66a-3 of the diffusion plate restraining pin 66a of the diffusion plate 66 is forcibly inserted from the front side into the locked hole 73c of the lower frame 73, and the shaft portion 66a-2 is inserted into the locked hole 73c. The engaging head 56b can be locked by engaging the locking head portion 56b with the peripheral edge of the back surface of the locked hole 73c. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

It is a disassembled perspective view of the direct type | mold backlight of 1st Embodiment of this invention. It is a perspective view which shows the lamp house etc. of the backlight of 1st Embodiment. (A) is sectional drawing which shows the AA line cross section of FIG. 2, (B) is an enlarged view of the B section of (A). It is sectional drawing of the diffusion plate restraint pin vicinity of 1st Embodiment. It is a top view of the diffusion plate of a 1st embodiment. It is a top view of the diffusion plate of a 2nd embodiment. It is a top view of the diffusion plate of a 3rd embodiment. It is a top view of the diffusion plate of a 4th embodiment. It is sectional drawing of the diffusion plate restraint pin vicinity of 5th Embodiment. It is sectional drawing of the diffuser plate restraint pin vicinity of 6th Embodiment. It is sectional drawing of the diffusion plate restraint pin vicinity of 7th Embodiment. It is sectional drawing which shows the backlight of a prior art example. It is sectional drawing which shows the trouble of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fluorescent lamp 10 Direct type | mold backlight 11 Lower frame 12 Reflecting plate 13 Light source holding member 14 Diffusion plate restraint pin 14c Shaft part 14d Locking head 16 Diffusion plate 17 Upper frame 18, 19 Mounting hole 18a, 19a Locked hole LH Lamp house

Claims (6)

A light source is disposed behind the liquid crystal panel of the liquid crystal display device, and is spaced from the bottom of the flat lamp house that opens to the liquid crystal panel side. The light source is disposed so as to cover the opening of the lamp house. In a direct type backlight having a diffusion plate provided,
Diffusing plate restraining means for connecting the diffuser plate to the bottom of the lamp house other than the location of the light source and the diffuser plate is provided, and the diffusing plate restraining means restrains the diffuser plate from bending at least toward the liquid crystal panel. A direct type backlight characterized by having a structure. The diffusion plate restraining means is a diffusion plate restraining pin standing on the bottom of the lamp house and having a locking portion on the tip side, and a locked portion provided at a position corresponding to the locking portion of the diffusion plate. And
The direct type backlight according to claim 1, wherein the locking portion is configured to be engaged with the locked portion to restrain movement in a direction perpendicular to a plate surface of the diffusion plate. The diffuser plate restraining means includes a diffuser plate restraining pin that is suspended from the diffuser plate and has a latching portion on a front end side, and a latched portion provided at a position corresponding to the latching portion at the bottom of the lamp house. With
The direct type backlight according to claim 1, wherein the locking portion is configured to be engaged with the locked portion to restrain movement in a direction perpendicular to a plate surface of the diffusion plate. Provided with a large-diameter locking head at the tip of the shaft portion of the diffusion plate restraining pin to be the locking portion, the locked portion is a locked hole,
The locking head is forcibly inserted into the locked hole, the shaft portion is fitted into the locked hole, and the locking head is brought into contact with the peripheral edge of the locked hole. The direct type backlight according to claim 2 or 3, which is stopped.   The direct-type backlight according to claim 4, wherein the diffusion plate restraining pin is provided with a support portion that comes into contact with a peripheral edge of the locked hole opposite to the locking head. A plurality of the diffusion plate restraining pins are provided, and one of the diffusion plate restraining pins is for positioning, and the shaft portion is closely fitted to the locked hole to restrain the movement in the surface direction of the diffusion plate. While
The remaining diffusion plate restraining pin is provided with a clearance for absorbing thermal expansion in the surface direction of the diffusion plate between the shaft portion and the locked hole. Type backlight.

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