JP2000047208A - Liquid crystal display - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the occurrence of flicker on the screen due to electrical noise, and to suppress the leakage of the output high voltage to the ground, reduce the power consumption, and realize a high-brightness backlight. Provided is a liquid crystal display device capable of improving luminous efficiency. A plurality of linear lamps are arranged in parallel below a liquid crystal display panel, an opening is provided in a lower metal frame, and a high-voltage high-frequency AC generating circuit board for lighting the linear lamp. A high-voltage generating transformer 13 and a dimming circuit 26 are mounted on one side of the lower surface of the device, and the high-voltage high-frequency AC generating circuit board 9 is disposed in the opening 21. And the upper surface of the lower metal frame 8 and the lower surface of the mold case 7 are in close contact with each other.

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, to a liquid crystal display device provided with a backlight which does not easily cause flicker on a screen and has high luminance and luminous efficiency.

[0002]

2. Description of the Related Art Liquid crystal display devices have begun to be widely used as display terminals for information processing equipment (OA equipment) such as office computers and personal computers because of their features of being thin and lightweight and having high image quality comparable to a cathode ray tube.

In this liquid crystal display device (ie, liquid crystal display module), a transparent insulating substrate made of, for example, two sheets of glass having display electrodes provided on at least one opposing surface is overlapped with a predetermined gap. The two substrates are bonded together by a liquid crystal sealing material provided in a frame shape (a square shape) on the peripheral portion between the two substrates, and a sealing material between the two substrates is provided through a liquid crystal sealing opening provided in a part of the sealing material. A liquid crystal display panel (ie, a liquid crystal display element, LCD: liquid crystal display (Liq)) in which a liquid crystal is sealed inside the liquid crystal panel and a polarizing plate that transmits only a certain amount of polarized light is provided outside the two substrates.
uid Crystal Display)), a backlight which is arranged below the liquid crystal display panel, emits light from the surface, supplies light from the back to the liquid crystal display panel, and serves as a light source for displaying an image, and a liquid crystal display panel. A driving circuit board that is disposed outside the outer peripheral portion and applies a voltage corresponding to a display image signal to the electrodes, a liquid crystal display panel and a plastic mold case that stores and holds a backlight, and stores the respective members, It consists of a metal upper shield case with an open display window, a metal lower shield case, and the like.

As a backlight of a liquid crystal display device, there is a backlight having a built-in linear lamp such as a cold cathode or hot cathode fluorescent tube in order to obtain a high contrast and bright color display.

In particular, there is an increasing demand for a liquid crystal display device having a large screen size (for example, 15 to 21 inches) for a computer monitor, and the backlight of the liquid crystal display device is bright and has been used for a long time. In this case, it is required that the luminance does not decrease.

Generally, a cold cathode or hot cathode fluorescent tube is
There is a characteristic that the luminance decreases as the use time elapses.

As a countermeasure against the decrease in luminance due to long-term use, a light guide plate having substantially the same size as that of the light guide plate is disposed directly below the liquid crystal display panel, and a linear lamp is disposed near the side surface of the light guide plate along the side surface. However, there is a method in which the linear lamp is replaced when the luminance is lowered by adopting a structure in which the linear lamp can be easily inserted and removed, which is called a side edge method.

[0008] Such a side-edge type backlight is disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 7-181489, and the academic literature (IDU96-59, 1996, IDY9).
6-147, p. 43-48).

In the backlight of the side edge type, there is a problem that the brightness of the screen decreases as the screen size increases. In this method, there is a limit to this measure, and in particular, the brightness decreases at the center of the screen, which is contrary to the demand for uniform brightness on a large screen. Further, the light guide plate made of an acrylic plate or the like is heavy, and is very heavy on a large screen. For this reason, the strength of the frame holding the light guide plate must be increased, which further increases the weight and the manufacturing cost.

Although it is possible to increase the number of fluorescent tubes arranged on the side surface of the light guide plate in order to prevent this decrease in luminance, a light guide plate having a rectangular planar shape basically has four light guide plates. It is the limit to arrange fluorescent tubes in each,
Such an arrangement is contrary to recent demands for increasing the length of the liquid crystal display device in the vertical and horizontal directions and reducing the width of a so-called frame portion, which is the outer peripheral portion of the display screen. It is also possible to arrange a plurality of fluorescent tubes on the side of the light guide plate,
In this case, heat is concentrated even in the cold cathode fluorescent tube, and it is not possible to disregard adverse effects such as display unevenness caused by heat of the liquid crystal display panel.

[0011] Further, as a backlight having a high luminance,
There is a direct type in which a plurality of linear lamps are arranged in parallel on a reflecting plate having a wavy or sawtooth cross section.

References describing such a backlight include, for example, JP-A-1-169482, JP-A-3-219278, and JP-A-4-209.
No. 89 publication.

In the direct type backlight, if the number of linear lamps is small, the luminance of the whole backlight does not increase, and it is necessary to increase the luminance of the linear lamp. However, in this case, the shadow of the linear lamp is seen from the display screen. If the distance between the liquid crystal display panel and the linear lamp is increased to avoid this, the thickness of the liquid crystal display device increases. Further, when the number of linear lamps is reduced to increase the brightness, adverse effects such as uneven display due to heat of the liquid crystal display panel occur.

In the liquid crystal display device, a frame for accommodating a liquid crystal display panel, a backlight and the like, and covering the outside of the device is formed of a metal plate, and a linear lamp as a light source is formed by a heat radiation effect of the metal plate. The heat generated by the metal plate prevents adverse effects on display quality, and the metal plate shields electromagnetic waves.

The liquid crystal display device has a high-voltage high-frequency AC generation circuit board for lighting a linear lamp,
On the circuit board, a high-voltage generating transformer for generating a high-voltage high-frequency AC voltage, a dimming circuit for equalizing the luminance of a plurality of linear lamps, a lamp cable of the linear lamp and an output of the transformer are connected. Electronic components such as connectors
Has been implemented.

[0016]

As described above, the size of the display screen of a liquid crystal display device for a computer monitor is increasing year by year, and the backlight is also increasing in size.

Further, there is a strong demand for higher brightness, and a brighter, that is, stronger backlight is required. As described above, there are a side edge type and a direct type backlight as described above, but for a higher luminance (especially in a large screen), a direct type method which can easily increase the number of linear lamps is advantageous. It is.

However, in the direct type, the thickness of the device is increased as compared with the side edge type. For this reason, conventionally, a high-voltage high-frequency AC generation circuit board for emitting a linear lamp is arranged in close contact with a metal frame to reduce the thickness of the entire device. However, when the high-voltage high-frequency AC generation circuit board is placed in close contact with the metal frame, the ground level is greatly fluctuated by electric noise because the voltage for lighting the linear lamp is high voltage and high-frequency AC voltage. There is a problem that the noise is caused on the display of the image signal and the display screen flickers. Furthermore, when the high-voltage high-frequency AC generation circuit board is disposed in close contact with the metal frame, the output high voltage leaks to the ground, increasing power consumption and reducing the luminous efficiency of the backlight.

An object of the present invention is to reduce the occurrence of flicker on the screen due to electric noise, suppress the leakage of the output high voltage to the ground, reduce the power consumption, and improve the brightness of the backlight. An object of the present invention is to provide a liquid crystal display device capable of improving luminous efficiency.

[0020]

In order to solve the above-mentioned problems, the present invention provides a liquid crystal display panel, a backlight disposed below the liquid crystal display panel, and a linear lamp constituting the backlight. A high-voltage high-frequency alternating-current generating circuit board, an electrically insulating frame that holds the backlight, and a metal frame that covers the outside of the liquid crystal display device. An opening is provided in the frame, and all or a part of the high-voltage high-frequency AC generation circuit board is arranged in the opening.

Also, a liquid crystal display panel, a backlight including a plurality of linear lamps arranged substantially in parallel below the liquid crystal display panel, and a high-voltage high-frequency AC generation circuit for emitting the linear lamps A substrate, an electrically insulating frame that holds the backlight, and a metal frame that covers the outside of the liquid crystal display device; an opening is provided in the metal frame on the lower surface side of the liquid crystal display device; All or a part of the high-voltage high-frequency AC generation circuit board is disposed in the opening, and in the opening, the whole or a part of the upper surface of the high-voltage high-frequency AC generation circuit board is connected to the electrically insulating frame. The upper surface of the metal frame except for the opening is closely attached to the lower surface of the electrically insulating frame.

Further, the high-voltage high-frequency AC generation circuit board is fixed to one or both of the metal frame and the electrically insulating frame.

On the lower surface of the high-voltage high-frequency AC generation circuit board, electronic components including a high-voltage generation transformer and a dimming circuit are mounted on one side, and all or a part of the upper surface of the high-voltage high-frequency AC generation circuit substrate is mounted. The opening is in close contact with the lower surface of the electrically insulating frame.

A high-voltage generating transformer is provided on the lower surface of the high-voltage high-frequency AC generating circuit board, and a portion provided with the high-voltage generating transformer is disposed in the opening.

Further, a dimming circuit is provided on the lower surface of the high-voltage high-frequency alternating-current generating circuit board, and a portion provided with the dimming circuit is arranged in the opening.

Further, the ground of the high-voltage high-frequency high-frequency AC generation circuit board is electrically connected to the metal frame.

Further, a reflector having a downwardly convex mountain shape in cross section for each linear lamp is provided below the linear lamp, and the voltage high-frequency AC generation circuit board is disposed below the reflector. It is characterized by having done.

According to the present invention, an opening is provided in the metal frame below the backlight, and the entire high-voltage high-frequency AC generating circuit board or a portion provided with a high-voltage generating transformer or a dimming circuit is provided in the opening. By placing some,
Prevents the high-voltage generating transformer or dimming circuit from sticking to the metal frame, reducing the occurrence of flicker on the screen due to electrical noise, and suppressing the leakage of output high voltage to the ground. Power consumption can be reduced and the luminous efficiency of a high-luminance backlight can be improved.

On the lower surface of the high-voltage high-frequency AC generation circuit board, electronic components such as a high-voltage generation transformer and a dimmer circuit are mounted on one side, and all or a part of the upper surface of the high-voltage high-frequency AC generation circuit substrate is opened. By fixing the high-voltage high-frequency AC generation circuit board to one or both of the metal frame and the electrically insulating frame, the thickness of the device can be further reduced by closely adhering to the lower surface of the electrically insulating frame. it can.

Further, the upper surface of the liquid crystal display device, except for the opening of the metal frame on the lower surface side, is brought into close contact with the lower surface of the electrically insulating frame, so that the linear lamps and the electronic components mounted on various circuit boards are mounted. The heat radiation effect on heat generation can be increased.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings described below, those having the same functions are denoted by the same reference numerals, and the repeated description thereof will be omitted.

FIG. 1 is an exploded schematic perspective view of a liquid crystal display module according to an embodiment of the present invention, FIG. 3 is a schematic sectional view taken along line AA of FIG. 1, and FIGS. 5 (a) and 5 (b). 3A is a schematic plan view of a main part of a direct backlight, FIG. 3A is a state in which a connector of a lamp cable of a linear lamp is connected, and FIG.
Indicates a state in which the connector of the lamp cable is disconnected.

In FIG. 1, 1 is a metal upper frame, for example, 2 is a liquid crystal display panel, 18 is a scanning signal electrode side driving circuit board, 19 is a video signal electrode side driving circuit board, 20
Is a DC / DC converter controller board, 3 is a diffusion sheet (only one is shown in FIG. 3), 4 is a diffusion plate, 5 is a lamp reflector (reflection plate), and 6 is a linear lamp (for example, a cold cathode fluorescent tube ( CFL)), 7 is, for example, a white plastic molded case (that is, an electrically insulating frame) that stores and holds the liquid crystal display panel 2 with a circuit board and a backlight, 8 is a lower metal frame, and 9 is a high voltage high frequency. An AC generating circuit board 13 is a high-voltage generating transformer, and 21 is an opening for accommodating the high-voltage high-frequency AC generating circuit board 9 provided on the lower metal frame 8.

In FIG. 3, reference numeral 10 denotes a polarizing plate, 11 denotes a transparent insulating substrate made of glass or the like constituting the liquid crystal display panel 2, 12 denotes a liquid crystal layer sandwiched between two transparent insulating substrates 11, and 14 denotes a low voltage. The side lamp cable 16 is a connector.

In FIG. 5, 14 is a low voltage side lamp cable of the linear lamp 6, 15 is a high voltage side lamp cable,
13 is provided on the high-voltage high-frequency AC generation circuit board 9;
A high voltage generating transformer for generating a high voltage for lighting the linear lamp 6, a dimming circuit 26 for equalizing the luminance of the eight linear lamps 6, and 17 (FIG. 5B) each line Connectors (cable sockets) provided at the distal ends of the lamp cables 14 and 15 of the linear lamp 6, and 16 denotes a connector (cable socket) into which the connector 17 of the linear lamp 6 is inserted.
It is.

In the present embodiment, as shown in FIGS. 1 and 3, eight linear lamps 6 are arranged under the liquid crystal display panel 2, so that the brightness is high, and especially 15 inches or more (15 to 2).
This is advantageous in a liquid crystal display device having a large screen (1 inch). On the lower surface of the high-voltage high-frequency AC generation circuit board 9 for lighting the linear lamp 6, electronic components such as a high-voltage generation transformer 13, a dimming circuit 26 and a connector 16 are mounted on one side, as shown in FIG. ing. Also, eight linear lamps,
The eight high-voltage generating transformers 13, eight connectors 16, and eight dimming circuits 26 provided corresponding to these are all arranged at the same pitch. With this arrangement, the low voltage side lamp cable 1 of each linear lamp 6
4. The lengths of the high-voltage side lamp cables 15 are the same, and the conditions such as the material and diameter of each cable are the same, so that the wiring resistance values are the same.
As a result, the tube current flowing through each linear lamp 6 becomes uniform, the luminance of each linear lamp 6 becomes uniform, and the uniformity of the luminance of the display screen can be improved. Further, since the difference between the tube currents of the linear lamps 6 is small, the dimming circuit 26 that adjusts the tube current of the linear lamps 6 by feedback so as to keep the tube current constant.
, The brightness balance of each linear lamp 6 can be easily adjusted because the feedback can be easily applied. Also, the IC constituting the dimming circuit 26 is provided for each of the eight linear lamps.
For example, the number of ICs can be reduced.

Further, since the lamp cables 14 and 15 are arranged with a minimum length and the length of the low-voltage side lamp cable 14 is short, electric noise generated from the cable is reduced, and the display by the electric noise is performed. The deterioration of quality can be suppressed. Further, the leakage of the high voltage current from the lamp cable 14 can be reduced, the loss of power consumption is reduced, and the luminous efficiency of the backlight is improved.

As shown in FIGS. 1 and 3, a lamp reflector 5 is disposed below each of the eight linear lamps 6, and each of the lamp reflectors 5 has a cross-sectional shape. Has a downwardly convex mountain shape, and has a waveform in which peaks and valleys are alternately arranged as a whole. Note that a sawtooth shape may be used instead of the waveform. In addition, between the liquid crystal display panel 2 and the linear lamp 6 and the lamp reflector 5, a thickness is set to prevent damage to the linear lamp 6, improve the strength of the mold case 7, and make the luminance of the light emitting region uniform. A transparent acrylic diffusion plate 4 having a white or white dot print of 1 to 3 mm in diameter is provided.

Further, between the liquid crystal display panel 2 and the diffusion plate 4, light is condensed and the shadow of the linear lamp 6 is prevented from being seen when the display screen is viewed from an oblique direction. For uniformity, one or two diffusion sheets 3 are arranged. In addition, one or more brightness enhancement sheets may be arranged between the liquid crystal display panel 2 and the linear lamp 6.

As shown in FIG. 3, the low-voltage side cable 14 of the linear lamp 6 is disposed between the mountains below the lamp reflector 5 so as not to be seen from the display screen. Further, the low-voltage side cable 14 is spaced apart from the metal lower frame 8 to prevent a leak current from the cable 14.

FIG. 2 is a schematic perspective view showing a structure for holding the high-voltage high-frequency AC generation circuit board 9.

In FIG. 2, reference numeral 21 denotes a metal lower frame 8.
, An opening 22 for accommodating the high-voltage high-frequency AC generation circuit board 9 provided on the lower frame 8, a holding portion for the high-voltage high-frequency AC generation circuit board 9 provided integrally with the lower frame 8, and a high-frequency high-frequency AC generation circuit board 9 The fixing screw holes provided, 24 are screw holes provided in the mold case 7, and 25 is a screw. In addition,
In FIG. 2, the high-voltage generating transformer 1 mounted on one side on the lower surface of the high-voltage high-frequency AC generating circuit board 9 facing upward.
3. Electronic components such as the dimming circuit 26 and the connector 16 are not shown (see FIGS. 5 and 4A).

As shown in FIGS. 1 and 3, the high-voltage high-frequency AC generation circuit board 9 is fixed to the metal lower frame 8 and the mold case 7 located on the back side (lower side) of the liquid crystal display module. For example, as shown in FIG. 2, the high-voltage high-frequency AC generation circuit board 9 is slightly larger than the circuit board 9 and the storage opening 2 formed in the metal lower frame 8.
1, two corners of the circuit board 9 are held by two holding parts 22 formed together with the opening 21 by press working, and two screws 25, It is fixed to the mold case 7 by holes 23 and 24. In addition, in order to make the device thinner, the upper surface of the high-voltage high-frequency AC generation circuit board 9 and the lower surface of the mold case 7 are in close contact with each other at the opening 21. As described above, the electronic components such as the high-voltage generating transformer 13, the dimming circuit 26, the connector 16 and the like are mounted on one surface of the lower surface of the high-voltage high-frequency AC generating circuit substrate 9, and the upper surface of the high-voltage high-frequency AC generating circuit substrate 9 and the mold case. Since the high-voltage high-frequency AC generation circuit board 9 is fixed to the lower metal frame 8 by the holding portion 22 and to the mold case 7 by two screws 25 so that the lower surface of the high-frequency high-frequency AC generation circuit 7 is in close contact with the lower case 7, it is useless. Eliminate space,
The thickness of the liquid crystal display module can be further reduced. Although not shown, the ground wiring of the high-voltage high-frequency AC generation circuit board 9 and the metal frame 8 are electrically connected at appropriate places.

In the present embodiment, as shown in FIGS. 2 and 1, an opening 21 is provided in the metal lower frame 8 and the high-voltage high-frequency AC generation circuit board 9 is arranged in the opening 21. Since the high-voltage generating transformer 13 and the dimming circuit 25 do not adhere to the metal lower frame 8, the occurrence of flicker on the screen due to electric noise is reduced, and the leakage of the output high voltage to the ground is reduced. By suppressing the power consumption, the power consumption can be reduced, and the luminous efficiency of the high-luminance backlight can be improved.

Further, as shown in FIG. 1, the metal lower frame 8 is in close contact with the lower surface of the mold case 7 over a wide area excluding the opening 21, so that the eight linear lamps 6 and the circuit board 18 are provided. , 19, 20, and 9 have a high heat radiation effect with respect to heat generated by the electronic components mounted thereon.

FIGS. 4A to 4C are schematic plan views showing examples of the arrangement of the high-voltage high-frequency AC generation circuit board 9 with respect to the opening 21 of the lower metal frame 8.

FIG. 4A corresponds to the embodiment shown in FIGS. 1 and 2, that is, an example in which the entire high-voltage high-frequency AC generation circuit board 9 is arranged in the opening 21. FIG.
In FIG. 5A, the size of the opening 21 is markedly larger than the size of the high-voltage high-frequency AC generation circuit board 9, but the size of the opening 21 is large. Approximately the same size as 9 and slightly larger.

As described above, in order to reduce the occurrence of flicker on the screen due to electric noise and to suppress the leakage of the output high voltage to the ground, the high-voltage high-frequency AC generation circuit board 9 is provided with an opening. 2 and 4 (a), the entire high-voltage high-frequency AC generation circuit board 9 is disposed in the opening 21 as shown in FIGS. It is not necessary. That is, at least one of the portion of the high-voltage high-frequency AC generation circuit board 9 provided with the high-voltage generation transformer 13 and the portion of the high-voltage high-frequency AC generation circuit board 9 provided with the dimming circuit 26 is disposed in the opening 21. What is necessary is just to make it not contact with the metal lower frame 8.

FIG. 4B shows an example in which the portion provided with the high-voltage generating transformer 13 is disposed in the opening 21, and FIG. 4C shows an example in which the portion provided with the dimming circuit 26 is disposed in the opening 21. Show.

4 (b) and (c), the size of the opening 21 is markedly larger than the size of the high-voltage high-frequency AC generation circuit board 9, but the size of the opening 21 in FIG. The width in the up-down direction is substantially the same as the width of the high-voltage high-frequency AC generation circuit board 9 and slightly larger, and the length in the left-right direction in FIG.
(B) is a length corresponding to the portion where the high voltage generating transformer 13 is provided, and (c) is a length corresponding to the portion where the dimming circuit 26 is provided.

The method of fixing the high-voltage high-frequency AC generation circuit board 9 in (b) and (c) is, as shown in FIG. 2, the holding portion 22 provided integrally with the lower metal frame 8.
(See FIGS. 4B and 4C) and screws (not shown; see FIG. 2). In (b) and (c), a part of the high-voltage high-frequency AC generation circuit board 9 is placed on the metal lower frame 8, but the thickness of the metal plate constituting the metal lower frame 8 is small. Since the thickness is extremely thin, 0.5 mm or less, the upper surface of the high-voltage high-frequency AC generation circuit board 9 and the lower surface of the mold case 7 do not hinder the close contact.
In (b) and (c), at the location indicated by the screw hole 23,
The high-voltage high-frequency AC generation circuit board 9 is fixed to the metal lower frame 8 and the mold case 7 using screws. The high-voltage high-frequency AC generation circuit board 9 can be fixed to one or both of the lower metal frame 8 and the mold case 7. For example, in FIG. 4A, the high-voltage high-frequency AC generation circuit board 9 is fixed to the mold case 7 using four screws, and the holding section 22 does not need to be provided.

In (b) and (c), since a part of the high-voltage high-frequency AC generation circuit board 9 is in contact with and mounted on the metal lower frame 8, The mounted electronic components have a high heat dissipation effect.

Although not shown, the ground wiring of the high-voltage high-frequency AC generation circuit board 9 and the metal frame 8 are electrically connected at appropriate places. For example,
In (b) and (c), the ground wiring of the circuit board 9 is connected to the screw hole 23 of the high-voltage high-frequency AC generation circuit board 9 via the screw fixed in the screw hole 23. Then, the ground wiring and the metal frame 8 are electrically connected.

In a general liquid crystal display device, the display changes from white display to black display or from black display to white display according to a change in applied voltage. In the present embodiment, for example, the liquid crystal layer has a twist angle of 90. ° Twisted nematic (TN) type or vertical alignment type TFT (thin film transistor) drive may be used, and the twist angle may be 200 to 26.
Super-twisted nematic (STN) type time-division driving at 0 ° may be used, or a horizontal electric field method that responds to a substrate surface with a horizontal electric field may be used.

The product Δnd of the refractive index anisotropy Δn of the liquid crystal layer and the cell gap d is 0.2 μm in the case of the TN type and the horizontal electric field type in order to make the contrast ratio and the brightness compatible.
The range is preferably from m to 0.6 μm, more preferably from 0.5 μm to 1.2 μm for the STN type, and preferably from 0.2 μm to 0.5 μm for the transverse electric field type.

As the transparent insulating substrate 11, for example, the surface of a glass substrate having a thickness of 0.7 mm is polished,
Two transparent electrodes made of TO (indium tin oxide) formed by sputtering were used. The dielectric anisotropy Δnε between these substrates is positive and the value is 4.
5, and the refractive index anisotropy Δn is 0.19 (589 nm,
(20 ° C.). Since the cell gap was 6 μm, Δnd was 1.41 μm.
After applying a polyimide-based orientation control film on the substrate surface, 25
The alignment control film was baked at 0 ° C. for 30 minutes to perform a rubbing treatment to obtain a pretilt angle of 3.5 ° (measured by a rotating crystal method). The rubbing directions of the alignment control films on the upper and lower substrates were set so that the twist angle (twist angle) of the liquid crystal molecules was 240 degrees in order to perform time-division driving. Here, the twist angle is defined by the rubbing direction and the type and amount of the optical rotatory substance added to the nematic liquid crystal. The maximum value of the torsion angle is limited because the lighting state near the threshold value is oriented to scatter light.
60 degrees is the upper limit, the lower limit is limited by contrast, and 200 degrees is the limit. In this embodiment mode, the torsion angle is set to 240 degrees in order to provide a liquid crystal display device capable of monochrome display with sufficient contrast even when the number of scanning lines is 200 or more. In addition, a single retardation film of Δnd = 0.4 μm made of polycarbonate was disposed between the transparent insulating substrate 11 and the polarizing plate 10 (not shown).

<< Outline of Liquid Crystal Display Panel >> FIG. 6 is a plan view showing one pixel of an active matrix type color liquid crystal display panel and its periphery in a liquid crystal display device to which the present invention can be applied, and FIG. The center (b) (cross section taken along the line 7-7 in FIG. 6), the left side (a) shows the cross section near the panel angle, and the right side (c) shows the cross section near the video signal terminal DTM to which the video signal drive circuit is connected. FIG.

As shown in FIG. 6, each pixel has two adjacent scanning signal lines (gate signal lines or horizontal signal lines) GL.
And two adjacent video signal lines (drain signal lines or vertical signal lines) DL (in a region surrounded by four signal lines). Each pixel includes a thin film transistor TFT, a transparent pixel electrode ITO1, and a storage capacitor Cadd. The scanning signal lines GL extend in the left-right direction in FIG. Video signal line DL
Extend in the up-down direction and are arranged in a plurality in the left-right direction.

As shown in FIG. 7, a thin film transistor TFT and a transparent pixel electrode ITO1 are formed on the lower transparent glass substrate SUB1 side with respect to the liquid crystal layer LC, and a color filter FIL and a light-shielding element are formed on the upper transparent glass substrate SUB2 side. A black matrix pattern BM is formed. A silicon oxide film SIO formed by dipping or the like is provided on both surfaces of the transparent glass substrates SUB1 and SUB2.

The light shielding film BM and the color filter FI are provided on the inner surface (the liquid crystal LC side) of the upper transparent glass substrate SUB2.
L, protective film PSV2, common transparent pixel electrode ITO2 (CO
M) and an upper alignment film ORI2 are sequentially laminated.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and it is needless to say that various modifications can be made without departing from the gist of the present invention. It is. For example, the present invention can be applied to a simple matrix type liquid crystal display device, a vertical electric field type or a horizontal electric field type active matrix type liquid crystal display device, or a COG (chip-on-glass) type liquid crystal display device. Needless to say. Further, the present invention is also applicable to a liquid crystal display device provided with a side edge type backlight having a light guide plate and a linear light source.

[0062]

As described above, according to the present invention,
In a liquid crystal display device, the occurrence of flicker on the screen due to electrical noise is reduced, the output high voltage leak to the ground is suppressed, the power consumption is reduced, and the luminous efficiency of the high-brightness backlight is improved. it can. In addition, it is advantageous for reducing the thickness of the device, and has a high heat radiation effect on heat generation of a backlight or the like.

[Brief description of the drawings]

FIG. 1 is an exploded schematic perspective view of a liquid crystal display module according to an embodiment of the present invention.

FIG. 2 is a schematic perspective view showing an example of a holding structure for a high-voltage high-frequency AC generation circuit board.

FIG. 3 is a schematic cross-sectional view of a main part taken along the line AA of FIG. 1;

FIGS. 4A to 4C are schematic plan views showing examples of the arrangement of a high-voltage high-frequency AC generation circuit board with respect to an opening of a metal lower frame.

FIGS. 5A and 5B are schematic plan views of a main part of a direct-type backlight of a liquid crystal display device according to an embodiment of the present invention.
(A) shows a state where the connector of the lamp cable of the linear lamp is connected, and (b) shows a state where the connector of the lamp cable is disconnected.

FIG. 6 is a main part plan view showing one pixel of an active matrix type color liquid crystal display panel and its periphery.

7A and 7B are cross-sectional views of a pixel portion of the matrix of FIG. 6 in the center (b), a left side (a) near a panel angle, and a right side (c) near a video signal terminal to which a video signal drive circuit is connected. It is.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Upper frame, 2 ... Liquid crystal display panel, 3 ... Diffusion sheet, 4 ... Diffusion plate, 5 ... Lamp reflector (reflection plate), 6 ... Linear lamp, 7 ... Mold case, 8 ... Lower frame, 9 ...
High voltage high frequency AC generation circuit board, 10 ... polarizer, 11 ...
Transparent insulating substrate, 12: liquid crystal layer, 13: high voltage generating transformer, 14: low voltage side lamp cable, 15: high voltage side lamp cable, 16, 17: connector, 18: scanning signal electrode side driving circuit board, 19 ... video signal electrode side driving circuit board, 20 ... DC / DC converter controller board, 21 ... storage opening, 22 ... holding part, 23, 24 ...
Screw holes, 25: screws, 26: dimming circuit.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shunsuke Morishita 3300 Hayano Mobara-shi, Chiba F-term (reference) 2H089 HA40 JA10 QA06 QA10 QA11 TA17 TA18 2H091 FA14Z FA16Z FA31Z FA32Z FA41Z FD01 FD03 FD06 GA11 LA04 LA08 LA11 LA16 5G435 AA03 AA12 AA16 BB12 BB15 CC09 CC12 EE03 EE04 EE05 EE26 EE34 EE37 FF03 FF06 FF13 GG12 GG24 GG26

Claims (8)

[Claims] 1. A liquid crystal display panel, a backlight disposed below the liquid crystal display panel, a high-voltage high-frequency AC generation circuit board for emitting a linear lamp constituting the backlight, and holding the backlight An electrical insulating frame, and a metal frame that covers the outside of the liquid crystal display device; an opening is provided in the metal frame on the lower surface side of the liquid crystal display device; Alternatively, a part of the liquid crystal display device is disposed in the opening. 2. A liquid crystal display panel, a backlight including a plurality of linear lamps arranged substantially in parallel below the liquid crystal display panel, and a high-voltage high-frequency AC generation circuit for causing the linear lamps to emit light. A substrate, an electrically insulating frame that holds the backlight, and a metal frame that covers the outside of the liquid crystal display device; an opening is provided in the metal frame on the lower surface side of the liquid crystal display device; All or a part of the high-voltage high-frequency AC generation circuit board is disposed in the opening, and in the opening, the whole or part of the upper surface of the high-voltage high-frequency AC generation circuit board is
A liquid crystal display device, wherein the liquid crystal display device is in close contact with a lower surface of the electrically insulating frame, and an upper surface of the metal frame excluding the opening is in close contact with a lower surface of the electrically insulating frame. 3. The high-voltage high-frequency AC generation circuit board is fixed to one or both of the metal frame and the electrically insulating frame.
The liquid crystal display device as described in the above. 4. An electronic component including a high-voltage generating transformer and a dimming circuit is mounted on one side of a lower surface of the high-voltage high-frequency AC generating circuit board, and all or a part of the upper surface of the high-voltage high-frequency AC generating circuit board is mounted. 3. The liquid crystal display device according to claim 1, wherein the opening is in close contact with a lower surface of the electrically insulating frame. 5. A high-voltage high-frequency AC generating circuit board, wherein a high-voltage generating transformer is provided on a lower surface of the circuit board, and a portion provided with the high-voltage generating transformer is disposed in the opening. Liquid crystal display device. 6. The liquid crystal according to claim 1, wherein a dimming circuit is provided on a lower surface of the high-voltage high-frequency alternating-current generating circuit board, and a portion provided with the dimming circuit is arranged in the opening. Display device. 7. The liquid crystal display device according to claim 1, wherein a ground of said high-voltage high-frequency alternating-current generating circuit board is electrically connected to said metal frame. 8. A reflecting plate having a downwardly convex chevron shape in cross section for each linear lamp is provided below the linear lamp, and the voltage high-frequency AC generating circuit board is disposed below the reflecting plate. 3. The liquid crystal display device according to claim 2, wherein: