JPH08184828A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: To prevent a current from being leaked and to reduce power consumption by providing a holding means to hold a gap between the light source and a condensing means to be constant between the light source and the condensing means. CONSTITUTION: By a silver reflection sheet 104, the light of a cold cathod fluorescent lamp 101 is condensed to a light transmission body 103. By the transmission body 103, the whole of a liquid crystal display element is irradiated with the light emitted from the lamp 101. The lamp 101 is interposed and held by a rubber bush 102 through the elasticity thereof. A projection part 102a provided on the bush 102 is positioned between the lamp 101 and the sheet 104 so as to prevent the lamp 101 from being near to or in contact with the sheet 104 and to simultaneously adjust the shape of the sheet 104 in order to enhance the condensing efficiency of the sheet 104 to the maximum. Since a distance between the lamp 101 and the sheet 104 is sufficiently held by the projection part 102a, stray capacity between the lamp 101 and the sheet 104 is reduced to an ignorable extent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, it is applied to a silver reflecting sheet for concentrating light of a cold cathode fluorescent lamp used as a light source of a liquid crystal display device in a certain direction. And effective technology.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display device having a silver reflection sheet for condensing light of a cold cathode fluorescent lamp, which has been used as a light source of a liquid crystal display device, in a certain direction is shown in FIG. There is something.

FIG. 7 shows a simple matrix type liquid crystal display module (LCM) which is one of the conventional liquid crystal display devices.
FIG.

A conventional liquid crystal display module (LCM) is
As shown in FIG. 7, a frame-shaped frame 70 made of a metal plate.
1, silicon spacer 702, liquid crystal display panel (LC
D) 703, drive circuit board (SEGP / B) 704, mold 705, prism sheet 706, cold cathode fluorescent lamp (cold cathode tube) 101, rubber bush 102, light guide plate 10.
3, the silver reflection sheet 104, the cable connector 707, and the lower frame 708 are stacked and assembled in the vertical arrangement relationship shown in FIG.

The mold 705 and the prism sheet 70
The cold cathode fluorescent lamp 101, the rubber bush 102, the light guide plate 103, and the lower frame 708 constitute a backlight for irradiating the liquid crystal display panel 703 with light.

As a backlight used in a conventional liquid crystal display module (LCM), a cold cathode fluorescent lamp 101 is closely arranged along a side surface of a light guide plate 103 made of a transparent synthetic resin plate for guiding light. Two types are known, one of which is arranged and the other of which a plurality of cold cathode fluorescent lamps 101 are arranged in parallel directly below the liquid crystal display panel 703.

FIG. 8 is a sectional view taken along the line AA in FIG. 7 of a backlight of the type in which the cold cathode fluorescent lamp 101 is arranged close to the side surface of the light guide plate 103.

The backlight shown in FIG. 8 is arranged so that the cold cathode fluorescent lamp 101 is close to the side surface of a light guide plate 103 made of a transparent synthetic resin plate for guiding light.

By arranging the cold cathode fluorescent lamp 101 in this manner, as much light as possible from the cold cathode fluorescent lamp 101 is guided to the light guide plate 103, and at the same time, space is saved.

Further, in order to collect light emitted in a direction different from that of the light guide plate 103 on the light guide plate without waste, a silver reflection sheet 104 is arranged so as to surround the cold cathode fluorescent lamp 101.

FIG. 9 is a partially enlarged view showing the structure of the silver reflection sheet 104 shown in FIG.

In FIG. 9, reference numeral 901 denotes a thickness 38 (μm).
Transparent polyethylene terephthalate (hereinafter "PE
The film of T ″.) Has good low-frequency electrical insulation characteristics as electric characteristics, and has heat resistance and mechanical strength such as tensile strength, bending strength, and compression strength.

Reference numeral 902 denotes a silver thin film having a thickness of 400 (Å), which forms a mirror surface together with PET901.

Reference numeral 903 is an acrylic white coat thin film having a thickness of 1 (μm), and 904 is an acrylic adhesive having a thickness of 15 (μm).

905 is an aluminum thin film having a thickness of 400 (Å), and 906 is a PET having a thickness of 25 (μm).
A film, 907, is a polyvinyl chloride (PVC) white-coated thin film having a thickness of 2 (μm).

[0016]

In the liquid crystal display device shown in the prior art, the frame 701 and the lower frame 708 are provided.
In addition to being a metal such as aluminum, these metal parts prevent malfunction of the drive circuit of the drive circuit board 704 due to external noise (measures against external noise) and suppress leakage of harmonics superimposed on the drive signal to the outside ( All were connected to the ground to prevent radiated radio waves.

Further, since the drive circuit board 704 is a printed circuit board, in addition to using many copper foils,
The ground wire occupies a large area on the board to prevent external noise and radiated radio waves.

Further, as shown in FIG. 9, the silver reflection sheet 104 has a silver thin film 902 made of metal and an aluminum thin film 9 as shown in FIG.
Have 05.

As a result, stray capacitance exists between the silver reflective sheet 104 and the metal component connected to the ground.

Therefore, when the distance between the cold cathode fluorescent lamp 101 and the silver reflection sheet 104 is insufficient, the cold cathode fluorescent lamp 1
01 and the silver reflection sheet 104 increase, and as a result, the cold cathode fluorescent lamp 101 to the silver reflection sheet 104,
A metal component such as the frame 701 and a current path to the ground of the power supply are formed, and a leak current flows, which is a major obstacle to reducing power consumption.

An object of the present invention is to provide a liquid crystal display device,
It is an object of the present invention to provide a technology capable of preventing a leak current and reducing power consumption.

The above objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0023]

Of the inventions disclosed in the present application, a representative one will be briefly described below.
It is as follows.

A liquid crystal display panel, a light source, a fixing means for fixing the light source, a condensing means for condensing the light emitted from the light source, and the liquid crystal panel with the light condensed by the condensing means. Is provided from the back surface, and the condensing means is a liquid crystal display device having at least one layer of a conductive material, and is located between the light source and the condensing means, Holding means for maintaining a constant distance between the light source and the light collecting means is provided.

[0025]

According to the above-mentioned means, the distance between the light source and the light-collecting means can be kept constant without being close to or in contact with each other.

Therefore, the stray capacitance between the light source and the light collecting means increases due to the proximity or contact between the light source to which an AC high voltage is applied and the light collecting means containing a conductive material. Can be prevented.

As a result, from the light source through the stray capacitance,
It is possible to minimize the leak current reaching the light condensing means.

As described above, the power consumption can be reduced by preventing the light source and the light condensing means from coming close to or in contact with each other, which causes an increase in the leak current.

[0029]

EXAMPLES The structure of the present invention will be described below with reference to examples.

In all the drawings for explaining the embodiments, parts having the same function are designated by the same reference numerals, and the repeated description thereof will be omitted.

(Embodiment 1) FIG. 1 is a perspective view showing a schematic structure of a backlight of a liquid crystal display device according to Embodiment 1 of the present invention.

In FIG. 1, 101 is a cold cathode fluorescent lamp which is an illuminating means, 102 is a rubber bush for protecting and fixing the cold cathode fluorescent lamp 101, and 102a is a protrusion provided on the rubber bush 102 and is held. It becomes a means.

Reference numeral 103 is a light guide for irradiating the light emitted from the cold cathode fluorescent lamp 101 to the entire liquid crystal display element, and 104 is a condensing means for collecting the light of the cold cathode fluorescent lamp 101 to the light guide 102 without waste. 3 shows a silver reflective sheet for shining.

The silver reflecting sheet 104 has the same structure as the silver reflecting sheet shown in FIG. 9 used in the conventional example.

FIG. 2 is a perspective view showing an example of the rubber bush 102.

In FIG. 2, 102a is a cold cathode fluorescent lamp.
01 and the silver reflection sheet 104 prevent the cold cathode fluorescent lamp 101 and the silver reflection sheet 104 from approaching or contacting each other, and at the same time maximize the light collection efficiency of the silver reflection sheet 104. It is a protrusion for adjusting the shape of.

Reference numeral 102b designates a holding portion for holding the cold cathode fluorescent lamp 101 by elastic force and holding it.

Reference numeral 102c supplements the force of the holding portion 102b for holding the cold cathode fluorescent lamp 101, and at the same time, the cold cathode fluorescent lamp 1 is provided.
This is an auxiliary portion for facilitating the sandwiching of 01.

Furthermore, the above-mentioned protrusion 102a and the holding portion 1
02b and the auxiliary part 102c are integrally configured.

Next, FIG. 3 shows a sectional view of the backlight of the liquid crystal display device shown in FIG. 1 taken along the line BB, and the effect of the projection 102a of the rubber bush 102 will be described.

First, the protrusion 102 of the rubber bush 102.
Since a enters between the cold cathode fluorescent lamp 101 and the silver reflecting sheet 104, the cold cathode fluorescent lamp 101 and the silver reflecting sheet 10
The distance to 4 is no closer than the thickness of the protrusion 102a.

On the other hand, the stray capacitance existing between the conductors has the property of being inversely proportional to the distance between the conductors.

Therefore, since the projection 102a holds a sufficient distance between the cold cathode fluorescent lamp 101 and the silver reflecting sheet 104, the stray capacitance can be reduced to a negligible level.

As a result, the feeling of the cold cathode fluorescent lamp 101 and the silver reflective sheet 104 in the leak current path from the cold cathode fluorescent lamp 101 to the ground via the silver reflective sheet 104, the frame 701 and the lower frame 708 can be cut off. Therefore, the leak current can be reduced to a negligible level, and power consumption due to the leak current can be prevented.

Further, the cold cathode fluorescent lamp 101 has a protrusion 102.
Since it is folded back along the outer periphery of a, the protrusion 102
By setting the shape of a to have the best light-collecting efficiency, the brightness of the backlight can be increased without increasing the light emission amount of the cold cathode fluorescent lamp 101.

FIG. 4 is a perspective view showing another example of the rubber bush applicable to the first embodiment.

Protrusion 4 of rubber bush 401 shown in FIG.
01a can sandwich the cold cathode fluorescent lamp 101 in the same manner as the sandwiching portion 102b of the rubber bush 401.

Further, the outer periphery of the projection 401a which is in contact with the silver reflection sheet 101 has a shape which maximizes the light collection efficiency.

FIG. 5 is a perspective view showing an example of a rubber bush applicable to the first embodiment.

The protrusion of the rubber bush 501 shown in FIG. 5 is composed of two protrusions 501a and 501b.

Furthermore, the outer circumferences of the protrusions 501a and 501b that are in contact with the silver reflection sheet 101 are shaped to maximize the light-collecting efficiency.

As described above, according to the first embodiment, when the distance between the cold cathode fluorescent lamp 101 and the silver reflection sheet 104, which has been a problem in the related art, is insufficient or when they are in contact with each other, the cold cathode fluorescent lamp is used. Stray capacitance, which causes a leak current flowing between the lamp 101 and the silver reflection sheet 104, is provided with a protrusion 102a on the rubber bush 102.
By sandwiching a between the cold cathode fluorescent lamp 101 and the silver reflecting sheet 104, the cold cathode fluorescent lamp 101 and the silver reflecting sheet 10
4 can be prevented from approaching or contacting with 4, and thus can be significantly reduced.

The distance between the cold cathode fluorescent lamp 101 and the silver reflection sheet 104 is limited by the structural restrictions of the liquid crystal display module in order to reduce the stray capacitance that causes the leakage current. It may be 0.5 mm or more.

As a result, there are the following effects.

(1) Since the leak current from the cold cathode fluorescent lamp 101 to the power supply ground via the silver reflection sheet 104 and the metal parts of the liquid crystal module can be greatly reduced, it is possible to reduce the power consumption due to the leak current. Become.

(2) Silver reflection sheet 10 on protrusion 102a
By changing the shape of the portion in contact with 4, the light collection efficiency can be increased, and thus the brightness can be increased without increasing the power consumption.

(3) The protrusion 102a has a rubber bush 10
Since it is integrally molded with 2, the number of parts is not increased.

(4) The protrusion 102a is formed of the rubber bush 10.
Since it is integrally molded with 2, it is possible to prevent an increase in the amount of work during assembly.

(Embodiment 2) FIG. 6 shows another embodiment 2 of the present invention.
FIG. 3 is a perspective view showing a schematic configuration of a backlight of the liquid crystal display device of FIG.

The second embodiment is an embodiment in which a ceramic spacer 601 is used instead of the protruding portion 102a of the rubber bush 102 in the first embodiment.

Next, parts different from the first embodiment will be described.

The rubber bush 602 shown in FIG. 6 is equivalent to the rubber bush used conventionally.

However, the shape of the surface of the spacer 601 which is in contact with the silver reflection sheet 104 is the shape that maximizes the light-collecting efficiency, like the protrusion 102a in the first embodiment.

Further, the shape of the side in contact with the cold cathode fluorescent lamp 101 is a shape that follows the cold cathode fluorescent lamp 101.

Then, at the time of assembling the liquid crystal display device, the spacer 601 is fixed to the cold cathode fluorescent lamp 101 with an adhesive and covered with the silver reflection sheet 104.

Then, as shown in FIG. 2 of the first embodiment, it is possible to maintain a sufficient space between the cold cathode fluorescent lamp 101 and the silver reflection sheet 104 for the thickness of the spacer 601, and at the same time, to provide the silver. Since the reflection sheet 104 is arranged along the outer periphery of the spacer 601, it has a shape that maximizes the light collection efficiency.

As described above, according to the second embodiment, the spacer 601 is provided, and the spacer 601 is fixed to the cold cathode fluorescent lamp 101 so as to be sandwiched between the cold cathode fluorescent lamp 101 and the silver reflection sheet 104. Allows cold cathode fluorescent lamp 10
1 and the silver reflecting sheet 104 can be prevented from approaching or contacting each other, the stray capacitance between the cold cathode fluorescent lamp 101 and the silver reflecting sheet 104 can be significantly reduced.

As a result, the leak current from the cold cathode fluorescent lamp 101 through the silver reflection sheet 104 and the metal parts of the liquid crystal module to the power supply ground can be greatly reduced, so that the power consumption due to the leak current can be reduced. Become.

Furthermore, the silver reflection sheet 10 of the spacer 601
By changing the shape of the portion in contact with 4, the light collection efficiency can be increased, and thus the brightness can be increased without increasing the power consumption.

Although two spacers 601 are used in this embodiment, one or more spacers may be used.

In the second embodiment, the spacer 601 is made of ceramic material, but the rubber bush 602 is used.
Of course, it is also possible to sandwich the cold cathode fluorescent lamp 101 with the same material.

Further, it goes without saying that any non-conductive material can be used.

As described above, the invention made by the present inventor is
Although the present invention has been specifically described based on the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the scope of the invention.

[0074]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) Leakage current can be prevented and power consumption can be reduced.

(2) Since the light collecting means can be held in the shape that maximizes the light collecting efficiency, the brightness can be increased without increasing the power consumption.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of a backlight of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing an example of a rubber bush according to the first embodiment.

FIG. 3 shows the backlight of the liquid crystal display device of Example 1 as B-
It is sectional drawing cut | disconnected by the B line.

FIG. 4 is a perspective view showing another example of a rubber bush applicable to the first embodiment.

FIG. 5 is a perspective view showing another example of a rubber bush applicable to the first embodiment.

FIG. 6 is a perspective view showing a schematic configuration of a backlight of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 7 is an exploded perspective view of a simple matrix type liquid crystal display module (LCM) which is one of conventional liquid crystal display devices.

FIG. 8 is a cross-sectional view of a backlight in which cold cathode fluorescent lamps are arranged close to each other along a side surface of a light guide plate.

FIG. 9 is a partially enlarged view of the structure of the silver reflection sheet as seen from above perpendicular to the paper surface.

[Explanation of symbols]

101 ... Cold cathode fluorescent lamp, 102, 401, 501, 60
2 ... rubber bush, 102a, 401a, 501a, 5
01b ... Rubber bush protrusion, 102b ... Rubber bush sandwiching portion, 102c ... Rubber bush auxiliary portion, 103
... light guide, 104 ... silver reflective sheet, 601 ... spacer,
701 ... Frame, 702 ... Silicon spacer, 703
... Liquid crystal display panel, 704 ... Drive circuit board, 705 ... Mold, 706 ... Prism sheet, 707 ... Cable connector, 708 ... Lower frame, 901, 906 ... Polyethylene terephthalate (hereinafter referred to as "PET") film, 902 ... Silver thin film, 903 ... Acrylic white coat thin film, 904 ... Acrylic adhesive, 905 ... Aluminum thin film, 907 ... Polyvinyl chloride (PVC) white coat thin film.

Claims (2)

[Claims] 1. A liquid crystal display panel, a light source, a fixing means for fixing the light source, a condensing means for condensing light emitted from the light source, and the light condensed by the condensing means. The liquid crystal panel is provided with an illuminating device that illuminates from the back side,
The light condensing unit is a liquid crystal display device having at least one layer of a conductive material, is located between the light source and the light condensing unit, and has a constant distance between the light source and the light condensing unit. A liquid crystal display device, comprising a holding means for keeping the liquid crystal display device in the liquid crystal display device. 2. The holding means is integrally molded with the fixing means as a protrusion extending from the fixing means between the light source and the light collecting means. Liquid crystal display device.