JP2002174811A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device wherein light leakage from an illumination unit on the periphery of an image display area is reliably prevented and the reduction of the thickness of the entire device is realized. SOLUTION: A reflection preventing member is disposed on the periphery of an aperture of a metal casing of the illumination unit so as to be superposed on a black matrix on the periphery of the image display area of a liquid crystal panel and a light shielding film is stuck to a front cover disposed on the upper side of the liquid crystal panel so as to be overlapped on the liquid crystal panel, and the end surface of the liquid crystal panel is coated with the reflection preventing material.

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 using a transmissive liquid crystal panel which displays an image by illuminating it with a backlight or the like.

[0002]

2. Description of the Related Art In recent years, liquid crystal displays have been used in display devices of information devices such as personal computers, and display devices of video devices such as portable televisions, video movies, and car navigation systems. Display devices have been widely used. In addition, in order to realize a bright display screen, many of these liquid crystal display devices adopt a configuration in which illumination light is applied from behind a display element by a built-in illumination unit.

In an illumination unit, an edge light system in which a light guide plate is placed on the back surface of a display element and a line light source such as a fluorescent discharge tube is disposed on an end surface of the light guide plate is said to be thin and excellent in luminance uniformity of a light emitting surface. It has a feature, and an edge light method is often adopted as a backlight method of a liquid crystal display device used in a notebook personal computer or the like in pursuit of thinness. In a liquid crystal display device used for a portable television, a car navigation system, or the like, an edge light method using two or more fluorescent discharge tubes or an L-shaped fluorescent discharge tube or In many cases, an edge light method using a U-shaped fluorescent discharge tube is adopted.

FIG. 2 shows a liquid crystal display device in which a conventional transmission type liquid crystal panel and an illumination unit are combined. The illumination unit UD is provided with a flat transparent light guide plate 1 that transmits light, a fluorescent discharge tube 2, and a reflection sheet 3 that guides light emitted from the fluorescent discharge tube 2 to an end face D1 of the light guide plate 1. I have. The light guide plate 1, the fluorescent discharge tube 2 and the like are made of a metal 9 below the light guide plate and a metal case 10 above the light guide plate.
The illumination unit is formed by being held by. In the lighting unit UD having such a configuration, each member is housed in a combination of a lower housing 9 and an upper housing 10 having a predetermined shape, and the lighting unit UD is provided.
A liquid crystal panel LD and a front cover 8 are mounted on the liquid crystal panel to form a liquid crystal display device.

Since the metal casings 9 and 10 have a shielding effect, they also have a role of reducing the influence of the electromagnetic waves generated from the fluorescent discharge tube 2 on the liquid crystal panel LD and external devices.

[0006] The reflection sheet 3 has a role of returning the light going out of the light guide plate 1 back into the light guide plate 1 and increasing the illumination light coming out of the light exit surface. As the reflection sheet 3, a white resin film having a high reflectance is used.

Above the light guide plate 1, that is, on the irradiation surface side, light correction sheets 4, 5, and 6 are arranged. The light correction sheets 4, 5, and 6 include a diffusion sheet and a prism sheet. By arranging an arbitrary number of sheets having various specifications as necessary, the light emitted from the light guide plate can be diffused.
The aim is to equalize the irradiation light and increase the brightness.

The lead wire 7 is an electric wire for externally supplying a voltage required for causing the fluorescent discharge tube 2 to emit light, and is held between the housing 9 and the light guide plate 1.

The liquid crystal panel LD mainly comprises an upper glass substrate 11 (CF glass substrate) sandwiching liquid crystal, a lower glass substrate 12 (array glass substrate), and front and rear polarizing plates 15 and 16. Have been. On the side where the fluorescent discharge tube 2 is arranged, the array glass substrate 12 is C
An LSI 13 for driving the liquid crystal panel LD is mounted on a portion which is larger than the F glass substrate 11 and where the array glass substrate 12 is exposed.

A black light-shielding mask 14 called BM is provided on the four sides around the image display area of the liquid crystal panel LD.
The inner surface of the F glass substrate 11 or the array glass substrate 12 is patterned to improve the appearance as a display element by reliably blocking light from the periphery of the image display area.

[0011]

However, in the conventional liquid crystal display device having the above structure, light leaks from the outside of the BM 14 provided around the image display area of the liquid crystal panel LD, so that the liquid crystal display device has a problem. There is a problem that visibility deteriorates.

[0012] The light leakage around the lighting unit UD
Light L1 that is emitted from the glass substrate and the liquid crystal display device after being repeatedly reflected in the glass substrate and the liquid crystal display device, and light L2 that emerges from the front surface of the CF glass substrate 11, There is a light L3 or the like that emerges in an oblique direction.

Although it is possible to reduce light leakage by sufficiently widening the width of the BM 14, the size of the CF glass substrate 11 and the size of the array glass substrate 12 are increased, and the size of the liquid crystal display device is increased. Problem. Further, when the BM 14 is extended to the end of the CF glass substrate without changing the size of the CF glass substrate 11, there is a problem that the BM 14 is corroded by infiltration of moisture between the CF glass substrate 11 and the array glass substrate 12, The BM 14 needs to be arranged with a certain distance from the end of the CF glass substrate. Therefore, in the liquid crystal panel LD, there is always a portion through which light passes between the BM 14 and the end T of the CF glass substrate.

As shown in FIG. 2, the upper front cover 8 is overlapped with the polarizing plate 15 on the CF glass substrate 11 side.
Although it is possible to reduce light leakage by adopting a structure that shuts out light coming out of the BM 14,
There is a problem that the light leakage of L3 cannot be prevented, and the thickness of the entire liquid crystal display device increases because the front cover 8 is further overlaid on the polarizing plate 15 on the CF glass substrate 11 side.

Accordingly, an object of the present invention is to provide a simple configuration using members constituting a liquid crystal display device, and to prevent light leakage from an illumination unit outside an image display area while keeping the external size of the liquid crystal display device compact. It is an object of the present invention to provide a liquid crystal display device that can completely prevent such a problem.

[0016]

In order to solve the above-mentioned problems, a liquid crystal display device according to the present invention comprises a pair of transparent substrates, and a pixel display area of any one of the pair of transparent substrates. A liquid crystal panel having a light-shielding mask formed on the periphery thereof, and a liquid crystal panel disposed on one side of the liquid crystal panel. The center is opened so as to fix the liquid crystal panel and not to block light entering the liquid crystal panel from the one side. First
A liquid crystal display device, comprising: a second housing disposed on the other side of the liquid crystal panel and having an open center so as not to block an image display area of the liquid crystal panel,
An antireflection film is disposed around the opening of the first housing so as to overlap with the light shielding mask.

Further, the antireflection film has an adhesive function, and adhesively fixes the liquid crystal panel and the first housing.

Further, a light-shielding film is attached to the second housing, and the light-shielding film is disposed so as to overlap the transparent substrate on the other side.

An anti-reflection coating material is disposed on an end surface of the transparent substrate on the other side, and the anti-reflection coating material is formed on any one of the pair of transparent substrates. It is composed of a coating material applied for moisture proof or insulation of the formed wiring.

Further, the first and second housings are constituted by metal housings.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.

The embodiment of the liquid crystal display device of the present embodiment mainly includes an illumination unit UD, a liquid crystal panel LD, and a front cover 8.

The illumination unit LD includes a light source 2, a flat light guide plate 1 for transmitting light from the light source 2, a reflection sheet 3 arranged along the back surface of the light guide plate 1, and an upper surface of the light guide plate 1. , And metal casings 9 and 10 that surround and support these members.

As the light source 2, a fluorescent discharge tube which emits light when driven by a high frequency voltage of about 30 to 80 kHz is generally used.

After assembling the light guide plate 1, the reflection sheet 3 and the light source 2, these members 1, 2, 3 are held by being housed in a box-shaped housing 9. The housing 9 includes the light guide plate 1
Is held from the outer peripheral side and the lower side, and further combined with the casing 9 fitted with the casing 9 from above.
The lighting unit UD is completed. Such housings 9, 10
Is made of a metal plate material in order to eliminate generation of resin dust due to contact with other members or the like at the time of assembly, and stainless steel, iron, or the like is used.

The housing 9 is made of a metal plate having a shielding effect in order to prevent image noise caused by an electromagnetic wave generated from the light source 2 affecting the liquid crystal panel LD.

Furthermore, since the metal plate is thinner than the resin material and can have higher rigidity, the housing 9 is made of a metal plate material, so that the overall thickness of the liquid crystal display device is reduced and the strength is improved. Can be achieved.

The light guide plate 1 is made of a material such as acrylic which has optimum optical characteristics such as transmittance and refractive index required for light transmission. A dot pattern or a groove pattern (not shown) whose shape is changed according to the distance from the light source 2 is provided on the back surface of the light guide plate 1 and the light correction sheet 4 installed on the front surface side. 5 and 6, the light emitted from the illumination unit UD is equalized and the brightness is increased. The light emitted from the light source 2 is collected on the incident side end face D1 of the light guide plate 1 and guided inside.

Light correction sheets 4, 5, and 6 are disposed above the light guide plate 1, that is, on the irradiation surface side. The light correction sheets 4, 5, and 6 are provided for equalizing the output light of the illumination unit UD and increasing the luminance.
Two diffusion sheets 4 and two prism sheets 5 and 6 are used. The diffusion sheet 4 is a sheet-shaped optical member used for diffusing light from the fluorescent discharge tube 2 and uniformly irradiating the liquid crystal panel 11.
Reference numeral 6 denotes a transparent resin film having a structure in which triangular regular grooves are cut. Light correction sheets 4, 5, 6
Is not limited to the diffusion sheet 4 and the prism sheets 5 and 6, and any number of sheets having various specifications may be provided as needed.

The liquid crystal panel LD mainly includes a front glass substrate 11 (CF glass substrate) and a rear glass substrate 12 (array glass substrate) sandwiching liquid crystal, and front and rear polarizing plates 15 and 16. ing. LCD panel LD
On the A side (two sides) of FIG.
An LSI 13 for driving the liquid crystal panel LD is mounted on a portion where the size is larger than the glass substrate 11 and the array glass substrate 12 is exposed.

A black light-shielding mask 14 called BM is provided on the four sides around the image display area of the liquid crystal panel LD with CF.
Patterning is performed on the inner surface of the glass substrate 11 or the array glass substrate 12, and the periphery of the image display area is reliably shielded from light to improve the appearance as a display element.

On the exposed portion of the array glass substrate 12, a wiring pattern (not shown) for transmitting a drive signal of the liquid crystal panel LD is formed in a thin film on the array glass substrate, and a panel driving LSI 13 is mounted. I have.

The housing 10 has an opening at the center so as not to block the light entering the liquid crystal panel LD from the lighting unit UD. It is designed to be located near the center of the BM 14. By doing so, even when the position of the liquid crystal panel LD and the position of the housing 10 are deviated due to dimensional accuracy and assembly variations, the image display area may be blocked by the housing 10 or the lighting unit may be outside the BM 14. Light is prevented from passing directly to the front of the liquid crystal display device.

The upper surface of the housing 10 has an anti-reflection function.
For example, black light shielding tapes M are arranged on four sides around the central opening. The light from the illumination unit UD is transmitted to the inside of the array glass substrate 12 and the housing 10 by the light shielding tape M.
It is possible to greatly reduce light that passes through the outside of the BM 14 to the front surface of the liquid crystal display device by repeatedly performing heavy reflection on the upper surface of the liquid crystal display device.

The light-shielding tape M can be applied as a black or gray double-sided tape. By bonding the liquid crystal panel LD and the housing 10 with double-sided tape,
The gap between the liquid crystal panel LD and the housing 10 is completely eliminated, and the reflection of light at the interface between the array glass substrate 12 and the housing 10 can be more effectively prevented. I know it is.

Further, the liquid crystal panel LD and the lighting unit U
It is also possible to prevent dust from entering from outside during D and causing display defects.

The front cover 8 is disposed above the liquid crystal panel LD, covers and protects the peripheral edge of the liquid crystal panel LD from above, and opens the central window W2 so as not to block the image display area of the liquid crystal panel LD. The size of the central window is set such that the polarizing plate 15 on the CF glass substrate 11 side and the front cover 8 are positioned on substantially the same straight line in the thickness direction of the liquid crystal display device, thereby reducing the overall thickness of the device. It is trying to make it.

Array glass substrate 12 and CF glass substrate 1
For the side B (two sides) where the ends of 1 overlap, CF
The front cover 8 is overlaid on the glass substrate 11, and a fixed distance S1 is set between the end of the polarizing plate and the end of the front cover in consideration of the dimensional variation of the polarizing plate 15 and the displacement of the liquid crystal panel LD with respect to the illumination unit UD. Is open.

The array glass substrate 12 is a CF glass substrate 1
The LSI 13 is mounted on the array glass substrate 12 on the A side protruding from 1 and the front cover end is arranged at a fixed distance S2 from the polarizing plate end. This is to prevent the problem that the corner of the CF glass substrate 11 comes into contact with the end of the front cover and the glass substrate is chipped even when the mounting position of the liquid crystal panel LD to the illumination unit UD varies. Although the front cover 8 can also overlap the CF glass substrate 11 on the side A,
It is necessary to increase the size of the CF glass substrate 11,
As a result, there is a problem that the size of the entire liquid crystal display device increases.

In order to prevent light leaking from the gap S2 between the CF glass substrate 11 and the front cover 8 on the side A where the CF glass substrate 11 and the front cover 8 are not overlapped, a light shielding tape is provided on the inner surface of the front cover 8. N is adhered, and the light-shielding tape N is disposed so as to protrude into the opening window W2 of the front cover 8 and overlap the CF glass substrate 11. With this light-shielding film N, it is possible to prevent light of the illumination unit UD leaking from the periphery of the BM 14. Also, a liquid crystal panel LD
Similarly, the light shielding tape N may be attached to the B side.

The light-shielding film N has a thickness of 50 to 200 μm.
A black resin film of a certain degree is used, and is previously attached to the front cover 8 with an adhesive or the like. The light-shielding film N also serves to protect the LSI 13 by covering the metal edge of the front cover 8 close to the LSI 13 on the array glass substrate 12.

The two types of light-shielding film M and light-shielding tape N are used in the vicinity of the image display area of the liquid crystal display device.
Although it is possible to reliably block the light of the lighting unit UD coming out of the vicinity of the BM 14,
It has been found that the light L3 which is reflected at the end T of the CF glass substrate and emerges in the oblique viewing direction is also effective in reducing the transmission of light in the apparatus due to the multiple reflection. This light is light that can be confirmed only when the liquid crystal display device is viewed from an oblique direction. This is light that is reflected by the difference with the refractive index of the outside air and comes out. With respect to this light, in addition to the light-shielding film M and the light-shielding tape N, by coating a material for preventing reflection on the end T of the CF glass substrate, it is possible to more effectively prevent light leakage.
As a material used at this time, a black resin may be thinly coated, or an effect may be obtained by thickly coating a resin having a refractive index close to that of the glass substrate.

Alternatively, wiring formed on the array glass substrate 12 (formed of aluminum or ITO).
By applying a UV curable resin 18 or a silicon resin 17 or the like applied for insulation and moisture proof so as to completely cover the end T of the CF glass substrate, the same light reflection preventing effect can be easily obtained. .

[0044]

According to the above-described structure, the illumination unit outside the image display area can be formed with a simple structure using the members constituting the liquid crystal display device, while keeping the external size of the liquid crystal display device compact. Thus, it is possible to provide a thin liquid crystal display device that does not leak light from the periphery.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a conventional liquid crystal display device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light guide plate 2 fluorescent discharge tube 3 reflection sheet 4, 5, 6 light correction sheet 7 lead wire 8 front cover 9, 10 case 11 CF glass substrate 12 array glass substrate 13 LSI 14 light-shielding mask 15, 16 polarizing plate 17 silicon resin 18 UV curable resin LD Liquid crystal panel UD Lighting unit M Light shielding film N Light shielding tape T CF glass substrate edge

Continued on the front page F term (reference) 2H089 HA40 JA10 QA05 QA10 QA11 QA13 TA13 TA17 TA18 2H091 FA14Z FA23Z FA32Z FA34X FA34Y FA42Z FD14 GA17 LA11 LA13 LA16 5G435 AA18 BB12 BB15 EE03 EE04 EE05 FF33 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03 FF03

Claims (6)

[Claims] A liquid crystal panel comprising a pair of transparent substrates, wherein a light shielding mask is formed around a pixel display area of one of the pair of transparent substrates; and a liquid crystal panel disposed on one side of the liquid crystal panel. A first housing fixed to the liquid crystal panel and having a central opening so as not to block light entering the liquid crystal panel from the one side; and a first housing disposed on the other side of the liquid crystal panel, The second is open at the center so as not to block the image display area
A liquid crystal display device comprising: a housing; and an antireflection film arranged around the opening of the first housing so as to overlap the light-shielding mask. 2. The antireflection film has an adhesive function,
2. The liquid crystal display device according to claim 1, wherein the liquid crystal panel and the first housing are bonded and fixed. 3. The liquid crystal display device according to claim 1, wherein a light-shielding film is attached to said second housing, and said light-shielding film is disposed so as to overlap with said transparent substrate on said other side. 4. The liquid crystal display device according to claim 1, wherein an antireflection coating material is disposed on an end face of said transparent substrate on said other side. 5. The anti-reflection coating material is formed of a coating material applied for preventing moisture or insulating wiring formed on any one of the pair of transparent substrates. The liquid crystal display device as described in the above. 6. The liquid crystal display device according to claim 1, wherein said first and second housings are made of metal.