JPH11295731A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an even and bright display on whole display screen by reducing difference in brightness and color tone between a high voltage side and a low voltage side of a linear lamp using direct backlight. SOLUTION: This liquid crystal display device comprises a liquid crystal panel PNL holding a liquid crystal layer 2 between a pair of transparent substrates 1, 1' having picture selection electrodes on at least either of the substrates placed to be opposed to each other, a lower polarizing plate 3 and an upper polarizing plate 3' placed interposing the liquid crystal panel PNL, a driving means for impressing a voltage on the above electrodes according to display signals, and an illumination light source BL for illuminating the liquid crystal panel PNL from the back plane. In this case, this device is provided with a light source having plural groups of two or more linear lamps 6a, 6', 6a",... in parallel, with the high and low voltage sides arranged adjacent to each other and placed in parallel with the back plane of the liquid crystal panel PNL.

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, in which the light distribution of an illumination light source installed immediately below a liquid crystal panel is made uniform, and the brightness and color difference in a display screen are reduced to achieve a bright and high brightness. The present invention relates to a liquid crystal display device capable of displaying a quality image.

[0002]

2. Description of the Related Art In a liquid crystal display device capable of displaying high-definition and color images for a notebook computer or a display monitor, an illumination light source (so-called "light source") for illuminating a liquid crystal panel from behind.
(Hereinafter, this backlight is also referred to as an illumination light source). As the backlight, there are known a side edge type in which a linear lamp is arranged on a side surface of a transparent plate formed of an acrylic resin or the like called a light guide plate, and a direct type in which a linear lamp is arranged just below the back of the liquid crystal panel. ing.

[0005] Notebook computers which require a thinner type employ a side edge type, and a liquid crystal display device for a display monitor uses a side edge type in order to reduce the depth.

However, in a large-sized liquid crystal display device such as a display monitor, in order to obtain a high-contrast and bright color display image, it is indispensable that the luminance does not decrease even after long-term use. A liquid crystal display device in which a lamp or a hot-cathode fluorescent lamp (hereinafter, referred to as a linear lamp) is installed immediately below a liquid crystal panel has been commercialized.

In order to ensure the uniformity of the illuminating light within the screen of the backlight, in the side edge method, a dot-like reflection pattern is formed below the light guide plate by printing or the like, and the dot density is further reduced. Is changed according to the distance from a linear lamp.

Japanese Unexamined Patent Publication No. Sho 51-13666 and Japanese Unexamined Patent Publication No. Sho 63-163 disclose such prior art.
309921 and the like.

[0007]

A large-screen display is possible.
2. Description of the Related Art As a liquid crystal display device that is bright and does not decrease in luminance even when used for a long time, there is a liquid crystal display device in which a linear lamp can be replaced with a side edge type backlight. However, if the screen size of the liquid crystal display device using the side edge method is further increased, there is a problem that the luminance at the center of the liquid crystal panel is reduced. There is a limit to adopting the side edge method. This decrease in the brightness of the central portion of the liquid crystal panel can be dealt with by increasing the number of linear lamps. In this case, however, the heat generated by the linear lamps is concentrated near the location where the linear lamps are installed in the backlight. There is a problem that a non-uniformity of the temperature distribution causes a deterioration of the quality of a displayed image, or a new problem arises, such as a necessity of installing a forced cooling unit to avoid the problem.

A direct type backlight in which a light source composed of a linear lamp and a reflecting plate and a backlight composed of a diffusion plate disposed on the information of the linear lamp and the like are disposed immediately below the liquid crystal panel (back side). This is an effective means for solving the above problem.

FIG. 13 is a schematic diagram for explaining a conventional liquid crystal display device having a direct backlight. LCD panel P
The NL sandwiches a layer of a liquid crystal composition (hereinafter simply referred to as a liquid crystal layer) 2 between a lower transparent substrate 1 and an upper transparent substrate 1 ′, and has an outer surface of each of the lower transparent substrate 1 and the upper transparent substrate 1 ′. And the upper deflection plate 3 '.
A backlight BL is disposed on the back (directly below) the liquid crystal panel PNL via an optical sheet 4 such as a prism sheet. The backlight BL includes a reflector 5, a plurality of linear lamps 6a to 6f provided above the reflector 5, and a diffusion plate 7 provided above the plurality of linear lamps 6a to 6f.

In the illustrated configuration, the reflector 5 constituting the backlight BL has irregularities along the linear lamps, and the linear lamps are positioned in the concave portions, so that the light emitted from each linear lamp can be effectively used. It is directed to the direction of the liquid crystal panel. Further, the diffusion plate 7 has a function of diffusing light from the linear lamps 6a to 6f and the reflector 5 and averaging the brightness distribution of illumination light to the liquid crystal panel PNL.

The plurality of linear lamps 6a to 6f are arranged in a predetermined direction in a plane parallel to the liquid crystal panel PNL.

FIG. 14 is a plan view of a light source constituting the backlight shown in FIG. A plurality of linear lamps 6a to 6
f are arranged one by one in the concave portion of the reflector 5, and the linear lamps are arranged in parallel at substantially uniform intervals so as to irradiate illumination light to a liquid crystal panel arranged above the reflector. I have.

FIG. 15 is a schematic diagram for explaining the installation state of the linear lamp and the difference in brightness between the high-pressure side and the low-pressure side. In the figure, the end with a black dot indicates the high pressure side.

In such a direct type backlight, the number of linear lamps to be installed is increased in order to increase the brightness of the illumination light in the screen, and the number of linear lamps to be installed in the case of using a long substrate. And the lamp current per linear lamp can be reduced to extend the life.

A plurality of linear lamps 6a, 6b, 6c, 6
d,... are the high voltage side leads 9a, 9b, 9c,
9,... And low-voltage side leads 10a, 10b, 10c, 10
d are located on the same side.

Conventionally, however, a plurality of linear lamps generally have high luminance on the high voltage side and low luminance on the low voltage side due to uneven application of the ionizing substance or phosphor film to be enclosed, and also have different color tones at both ends. Therefore, when the number of linear lamps is increased in response to an increase in the screen size, the lamp becomes brighter on the high voltage side and dark on the low voltage side, and the color tone differs between the high and low voltage sides. Causes a luminance gradient or a color difference gradient,
There is a problem that the brightness and the color tone of the display screen become uneven.

An object of the present invention is to provide a high quality liquid crystal display device which is bright and has high uniformity of luminance and color tone in a display screen.

[0018]

In order to achieve the above object, the present invention provides a backlight comprising a plurality of linear lamps, a reflector, and a diffuser provided directly below a liquid crystal panel, and the backlight is provided. 2 of the plurality of linear lamps
One or more of the linear lamps are arranged as a set and are arranged adjacent to the high-pressure side and the low-voltage side of the set of linear lamps.

That is, the present invention provides the following (1) to
A feature of the configuration described in (5) is provided.

(1) A liquid crystal panel having a liquid crystal layer sandwiched between a pair of transparent substrates having a pixel selection electrode on at least one of them opposed to each other, and an upper polarizing plate arranged with the liquid crystal panel interposed therebetween And a lower polarizing plate, a driving unit for applying a voltage according to a display signal to the electrode, and a light source for illuminating the liquid crystal panel from the back, and the illumination light source, with a high voltage side and a low voltage side adjacent to each other. A light source comprising a plurality of linear lamps arranged in parallel with the rear surface of the liquid crystal panel as a set of two or more arranged in parallel was provided.

As a problem of the direct-type backlight, since the linear lamps are arranged immediately below the display area of the screen of the liquid crystal panel, the brightness and color tone unevenness of the linear lamps directly affect the display. As described above, the high-pressure side of the linear lamp is brighter than the low-pressure side due to the limitation of the manufacturing process. Also, the color tones at both ends are different. Therefore, the above (1)
By alternately arranging the high-voltage side and the low-voltage side along the arrangement direction of the plurality of linear lamps as in the configuration described above, the luminance in the display area can be made uniform.

(2) The backlight in (1) is provided above a plurality of linear lamps, a light source comprising a reflector disposed below these linear lamps, and above the plurality of linear lamps. It consisted of a diffusion plate.

With this configuration, the light emitted from the linear lamps can be effectively used, and the luminance distribution of each linear lamp can be averaged to obtain uniform brightness on the entire display screen.

(3) The reflector in (2) has a plurality of uneven structures along the longitudinal direction of the linear lamp, and a set of linear lamps is arranged in each of the concave portions of the uneven structure. With this configuration, the light emitted from the linear lamp is effectively used, and the deviation of the brightness and the color tone is reduced.

(4) The high-pressure side and the low-pressure side of each of the adjacent linear lamps of the set of linear lamps arranged in each of the adjacent concave portions of the plurality of uneven structures in (3) are adjacently arranged. did.

According to this configuration, the light emitted from the linear lamp is effectively used, and the deviation of the brightness and the color tone is reduced.

(5) The diffusing plate in (2) has a diffusion pattern or a reflection pattern immediately above each of the sets of linear lamps for uniformizing the illumination light distribution by the linear lamps.

In the present invention, a twisted nematic (TN type) liquid crystal having a twist angle of about 90 degrees, a twist angle of 2
A liquid crystal display device using a super twisted nematic (STN type) liquid crystal of 00 to 260 degrees or a vertical alignment type (vertical electric field type) TFT or a horizontal electric field type liquid crystal display device operated by an electric field in a direction parallel to the substrate surface The present invention can also be applied to other types of liquid crystal display devices.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to examples.

FIG. 1 is a schematic diagram for explaining a schematic configuration of a first embodiment of a liquid crystal display device according to the present invention, and FIG. 2 is a plan view of a light source portion thereof.

This liquid crystal display device incorporates a direct backlight BL on the back of a liquid crystal panel PNL, wherein 1 is a lower transparent substrate, 1 'is an upper transparent substrate, 2 is a liquid crystal layer,
3 is a lower polarizing plate, 3 'is an upper polarizing plate, 4 is an optical sheet such as a prism sheet, 5 is a reflector, 6a, 6a', 6b, 6
b ', 6c, 6c', 6d, 6d ', 6e, 6e', 6
f and 6f 'are linear lamps, 7 is a diffusion plate, and 8 is a light source.

The reflector 5 has irregularities parallel to the longitudinal direction of the linear lamp, and the linear lamps 6a, 6a ', 6b, 6
b ', 6c, 6c', 6d, 6d ', 6e, 6e', 6
f, 6f 'form a pair, and each pair is arranged in the recess of the reflector 5.

These linear lamps 6a, 6a ', 6b,
6b ', 6c, 6c', 6d, 6d ', 6e, 6e',
6f and 6f 'are arranged such that their high-pressure side and low-pressure side are adjacent to each other in each set.

The liquid crystal panel PNL is of a simple matrix type in which the display changes from white to black or a black to white display in response to a change in applied voltage, a twisted nematic (TN) type having a twist angle of about 90 degrees or a vertical alignment type. Thin film transistor type, with a twist angle of 200 to 260
The liquid crystal panel is a super twisted nematic (STN) type, a horizontal electric field type that operates with an electric field in a direction parallel to the substrate surface, and other known various types.

In a TN type liquid crystal panel, the product Δnd of the refractive index anisotropy Δn of the liquid crystal layer and the cell gap (thickness of the liquid crystal layer) d is in the range of 0.3 to 0.6 μm to achieve both the contrast and the brightness. In the case of the STN type, the thickness is preferably in the range of 0.5 to 1.2 μm.

An STN type liquid crystal display device is taken as an example.
The details of the liquid crystal panel will be described below.
For the lower substrate 1 and the upper substrate 1 ′, a glass substrate having a thickness of 0.7 mm and a surface polished, and ITO (indium tin oxide) transparent electrodes formed by a sputtering method is used. The dielectric anisotropy Δnε between these substrates 1 and 1 ′ is positive, the value is 4.5, and the birefringence Δn is 0.14 (589n).
m, 20 ° C.) to form a liquid crystal layer with the nematic liquid crystal composition interposed therebetween, and the cell gap was 6 μm. Thereby, Δn
d becomes 0.85.

A polyimide alignment film was applied to the inner surfaces of the lower and upper substrates 1 and 1 'by a spinner, baked at 250 ° C. for 30 minutes, and rubbed to obtain a pretilt angle of 3.5 °. In addition, this pretilt angle was measured by a rotating product method. The rubbing directions of the alignment films formed on the lower substrate and the upper substrate were set such that the twist angle (twist angle) of the liquid crystal molecules constituting the liquid crystal layer 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 optically active substance added to the nematic liquid crystal composition. The maximum value of the twist angle is limited because the lighting state near the threshold value is an orientation that scatters light. The upper limit is about 260 degrees, the lower limit is limited by contrast, and the lower limit is about 200 degrees.
In this example, the twist angle was set to 240 degrees because the purpose was to provide a liquid crystal panel capable of monochrome display with sufficient contrast even with 200 or more scanning lines. Although not shown, between the lower substrate 1 and the lower polarizing plate 3 and between the upper substrate 1 ′ and the upper polarizing plate 3 ′, Δnd made of polycarbonate is used.
= 0.4 μm was disposed.

On the other hand, in a liquid crystal panel constituting a TN type liquid crystal display device, switching elements (active elements) such as thin film transistors and pixel electrodes are formed in a matrix on the inner surface of a lower substrate 1 and are formed on an inner surface of an upper substrate 1 ′. A counter electrode (common electrode) is formed, and an alignment film is formed on each of the opposing inner surfaces by a rubbing process so that the twist angle is around 90 degrees, and a vertical electric field is formed between the pixel electrode and the counter electrode. To control the liquid crystal molecules.

In a horizontal electric field type liquid crystal panel, a switching element (active element) such as a thin film transistor, a pixel electrode and a counter electrode are formed on the inner surface of the lower substrate 1 in a matrix, and the substrate is disposed between the pixel electrode and the counter electrode. The liquid crystal molecules are controlled by forming an electric field parallel to the plane.

Next, backlights for illuminating the liquid crystal panels of various liquid crystal display devices as described above from a flat surface will be described.

FIG. 3 is a schematic partial plan view for explaining a first embodiment of the arrangement of the linear lamps constituting the light source of the backlight of the liquid crystal panel. Linear lamps 6a, 6a ', 6b, 6
b ′, for example, is a cold cathode fluorescent lamp having a length of 400 mm and a diameter of 4 mm, having a high-voltage side electrode at one end and a low-voltage side electrode at the other end. The luminance is low and the color tone has a difference of 0.008 at the maximum in CIE chromaticity coordinates.

In this embodiment, the linear lamps 6a, 6a ',
The high voltage side leads 9a, 9b, 9c, 9d,.
However, the low voltage side leads 10a, 10b, 1
0c, 10d, ... are attached.

In this arrangement example, a set of linear lamps 6A,
6B (6a, 6a 'and 6b, 6b'...), The high-pressure side and the low-pressure side of the linear lamps 6a and 6a 'are adjacent to each other in the arrangement direction, and the linear lamps 6b and 6b'. ,
The high-pressure side and the low-pressure side are arranged adjacent to each other in the arrangement direction, and similarly, the high-pressure side and the low-pressure side are arranged adjacent to each other in the arrangement direction in a set of linear lamps similarly arranged in one concave portion of the reflector 5. Have been.

The arrangement of the linear lamps cancels out differences in brightness and color tone at the ends, so that luminance differences and color differences in the display screen of the liquid crystal panel are eliminated, and high-quality image display is achieved. Obtainable.

FIG. 4 is a schematic partial plan view for explaining a second embodiment of the arrangement of the linear lamps constituting the light source of the backlight of the liquid crystal panel. Linear lamps 6a, 6a ', 6b, 6
The high voltage side leads 9a, 9b, 9c, 9d,... are on the high voltage side (ends of the side with black dots) of b ′,... and the low voltage side leads 10a, 10b, 10c are on the low voltage side. , 10
d, ... are attached.

In this embodiment, a set of linear lamps 6A,
6B (6a, 6a 'and 6b, 6b',...), The high-pressure side and the low-pressure side of the linear lamps 6a and 6a ',. ',
The high-pressure side and the low-pressure side are adjacent to each other in the arrangement direction, and the high-pressure side and the low-pressure side are also adjacent to each other in the arrangement direction in a set of linear lamps similarly arranged in one recess of the reflector 5 The linear lamps (the linear lamp 6a 'and the linear lamp 6b in FIG. 4) adjacent to each other in the adjacent concave portion of the reflector are installed such that one high-pressure side is adjacent to the other low-pressure side.

Due to the arrangement of the linear lamps, the difference in brightness and color tone at the end between the linear lamps arranged in one concave portion of the reflector and the linear lamps in the adjacent concave portion is different. Because of the cancellation, the difference in luminance and the difference in color in the display screen of the liquid crystal panel is eliminated, and a higher quality image display can be obtained.

FIG. 5 is a schematic partial plan view for explaining a third embodiment of the arrangement of the linear lamps constituting the light source of the backlight of the liquid crystal panel. Linear lamps 6a, 6a'6c, 6
b, 6b ′, 6b ″, 6c, 6c ′, 6c ″... on the respective high-voltage sides (ends with black dots), high-voltage leads 9a,
9b, 9c, 9d,... And low-voltage side leads 10a, 10b, 10c, 10d,.

In this embodiment, linear lamps 6a, 6a'6a ", 6b, 6
b, 6b ",... are a set of 6A, 6B, 6C,
.., And the high-pressure side and the low-pressure side of each linear lamp constituting one set are adjacent to each other. Due to such an arrangement of linear lamps, differences in brightness and color tone at the ends are offset between linear lamps arranged in one concave portion of the reflector,
Brightness differences and color differences in the LCD panel display screen are eliminated,
High quality image display can be obtained.

FIG. 6 is a schematic partial plan view for explaining a fourth embodiment of the arrangement of the linear lamps constituting the light source of the backlight of the liquid crystal panel. Linear lamps 6a, 6a ', 6a ",
6b, 6b ', 6b ", 6c, 6c',..., The high-voltage side leads 9a, 9
, 9c, 9d,... and low-voltage side leads 10a, 10b, 10c, 10d,.

In this embodiment, linear lamps 6a, 6a'6a ", 6b, 6
b, 6b ",... are a set of 6A, 6B, 6C,
.., And a linear lamp in which the high-voltage side and the low-voltage side are adjacent in the arrangement direction in the set of linear lamps arranged in one adjacent recess of the reflector, and adjacent in the adjacent recess of the reflector (In FIG. 6, the linear lamp 6a ″ and the linear lamps 6b, 6
b "and 6c) are arranged such that one high-pressure side is adjacent to the other low-pressure side.

Due to the arrangement of the linear lamps, the difference in brightness and color tone at the end is caused between linear lamps arranged in one concave portion of the reflector and between linear lamps adjacent to each other in the concave portion of the reflector. Because of the cancellation, the difference in luminance and the difference in color in the display screen of the liquid crystal panel is eliminated, and a higher quality image display can be obtained.

FIG. 7 is an explanatory view of a first embodiment of the arrangement of the linear lamp, the reflector, and the diffuser constituting the backlight according to the present invention. The linear lamp described with reference to FIG. 3 or FIG. Corresponds to the first or second embodiment of the arrangement. FIG.
(A) is a sectional view, and (b) is a partial plan view of a diffusion plate.

A set of two linear lamps 6A, 6B, 6C,... (6a, 6a ', 6b,
6b ′,...) Are arranged, and the diffusion plate 11 is disposed above the diffusion plate 11. The diffusion plate 11 has a diffusion pattern 12 for diffusing light from the linear lamp directly above a set of linear lamps (6a, 6a ', 6b, 6b',...) Located thereunder.・ ・ Is formed. This diffusion plate was a white plate made of an acrylic resin, and a diffusion pattern was formed on its surface by dot printing.

By the diffusion patterns 12, the distribution of illumination light irradiating the liquid crystal panel is made uniform, the brightness and color tone of the display screen are prevented from being uneven, and a high quality glass display can be obtained.

FIG. 8 is a sectional view for explaining a second embodiment of the arrangement of the linear lamp, the reflector and the diffuser constituting the backlight according to the present invention.

A set of two linear lamps 6A, 6B, 6C,... (6a, 6a ', 6b,
6b ', 6c, 6c',...) Are arranged, and the diffusion plate 11 is provided above the arrangement. And, between two linear lamps arranged in the concave portion of the reflector 5, a mountain-shaped portion 5A extending in the longitudinal direction of the linear lamp is formed. Then, the diffusion plate 11 is provided immediately above the set of linear lamps (6a, 6a ', 6b, 6b',...) Located therebelow.
A diffusion pattern 12,... For diffusing light from the linear lamp is formed.

The distribution of illumination light for irradiating the liquid crystal panel is made uniform by the chevron 5A and the diffusion pattern 12,
Irregularities in brightness and color tone of the display screen are prevented, and a high-quality glass display can be obtained.

FIG. 9 is a sectional view for explaining a third embodiment of the arrangement of the linear lamp, the reflector and the diffuser constituting the backlight according to the present invention.

A set of three linear lamps 6A, 6B, 6C,... (6a, 6a ', 6)
a ", 6b, 6b ', 6b", 6c, 6c', 6c ",
..) are arranged, and the diffusion plate 11 is provided above the. Further, a flat portion 5B is formed on the bottom surface of the concave portion of the reflector 5. The diffusion plate 11 has a set of linear lamps (6a, 6a ', 6a ", 6a) located thereunder.
, 6b ', 6b ", 6c, 6c', 6c",...), a diffusion pattern 12 for diffusing light from the linear lamp is formed.

The distribution of illumination light for irradiating the liquid crystal panel is made uniform by the flat portion 5B and the diffusion pattern 12,
Irregularities in brightness and color tone of the display screen are prevented, and a high-quality glass display can be obtained.

FIG. 10 is a sectional view for explaining a fourth embodiment of the arrangement of the linear lamp, the reflector and the diffuser constituting the backlight according to the present invention.

A set of three linear lamps 6A, 6B, 6C,... (6a, 6a ', 6)
a ", 6b, 6b ', 6b", 6c, 6c', 6c ",
..) are arranged, and the diffusion plate 11 is provided above the. And, on the bottom surface of the concave portion of the reflector 5, a mountain-shaped portion 5C extending between the linear lamps in the longitudinal direction of the linear lamp is formed. The diffusion plate 11 has a set of linear lamps (6a, 6a ', 6a ", 6a) located thereunder.
, 6b ', 6b ", 6c, 6c', 6c",...), a diffusion pattern 12 for diffusing light from the linear lamp is formed.

The distribution of the illumination light illuminating the liquid crystal panel is made uniform by the chevron 5C and the diffusion pattern 12,
Irregularities in brightness and color tone of the display screen are prevented, and a high-quality glass display can be obtained.

The shape of the reflector 5 including the concave portion of the reflector and the chevron portion and the flat portion formed at the bottom thereof is not limited to the above shape. In each of the above embodiments, the concave shape is basically formed by a curved surface, but may be formed by a combination of flat surfaces without being limited to the curved surface.

In each of the embodiments described above, a diffusion pattern is formed by dot printing on a white acrylic plate to diffuse light from a light source to the liquid crystal panel side and the linear lamp side.
Instead of this diffusion pattern, a reflection pattern that reflects part of the light from the light source toward the linear lamp may be used. The reflection pattern can be formed by dot printing of the reflection material as in the case of the diffusion pattern.

FIG. 11 is an external view showing an example of a display monitor on which the liquid crystal display device according to the present invention is mounted.
The display monitor includes a main body 50 and a base 60, and the liquid crystal display device 30 is mounted on the main body 50. According to this display monitor, it is possible to obtain a high-quality image display in which the brightness of the display screen is uniform and there is no difference in color tone at the peripheral portion.

FIG. 12 is a block diagram for explaining an example of a peripheral circuit of a liquid crystal display device according to the present invention, and is a circuit diagram relating to a liquid crystal display device of a horizontal electric field type. The liquid crystal panel 30 composed of the lower substrate 1 and the upper substrate 1 'is a thin film transistor TFT
And a matrix of R, G, B three-color unit pixels driven by the above, and the above-described direct-type backlight is disposed on the back surface thereof.

That is, on the lower substrate 1, a gate signal line GL and a counter voltage signal line CL which extend in the effective pixel region in the x direction (row direction) and are juxtaposed in the y direction (column direction) are respectively provided. Drain signal lines DL that are insulated and extend in the y direction and are arranged in parallel in the x direction are formed. The gate signal line GL,
Three-color unit pixels R, G, and R are provided in a rectangular area surrounded by the counter voltage signal line CL and the drain signal line DL, respectively.
B is formed.

As its external circuit, a vertical scanning circuit GDRV
And a video signal driving circuit DDRV, and a scanning signal (voltage) is sequentially supplied to each of the gate signal lines GL by the vertical scanning circuit GDRV, and the video signal driving circuit DDRV is connected to the drain signal line DL in accordance with the timing. A video signal (voltage) is supplied.

The vertical scanning circuit GDRV and the video signal driving circuit DDRV are supplied with power from a liquid crystal driving power supply circuit CDRV / PW, and the host computer HO.
Image information from the CPU of the ST is divided into display data and a control signal by the controller CONT and input.

It should be noted that the present invention can be similarly applied to an active matrix type liquid crystal display device of a simple matrix type or a vertical electric field type.

[0074]

As described above, according to the present invention,
The luminance difference between the high-pressure side and the low-pressure side of the linear lamp can be reduced to less than 2% by actual measurement, and the color tone difference in the CIE color coordinates can also be reduced to 0.002 or less. The brightness of the liquid crystal display device can be made uniform over the entire display screen, and the liquid crystal display device with low power consumption and high visibility can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a schematic configuration of a first embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a plan view of a light source portion of the first embodiment of the liquid crystal display device according to the present invention.

FIG. 3 is a schematic partial plan view illustrating a first embodiment of an arrangement of linear lamps constituting a light source of a backlight of a liquid crystal panel.

FIG. 4 is a schematic partial plan view for explaining a second embodiment of the arrangement of the linear lamps constituting the light source of the backlight of the liquid crystal panel.

FIG. 5 is a schematic partial plan view for explaining a third embodiment of the arrangement of the linear lamps constituting the light source of the backlight of the liquid crystal panel.

FIG. 6 is a schematic partial plan view illustrating a fourth embodiment of an arrangement of linear lamps constituting a light source of a backlight of a liquid crystal panel.

FIG. 7 is an explanatory diagram of a first embodiment of an arrangement configuration of a linear lamp, a reflector, and a diffusion plate constituting a backlight according to the present invention.

FIG. 8 is a cross-sectional view illustrating a second embodiment of the arrangement of the linear lamp, the reflector, and the diffuser constituting the backlight according to the present invention.

FIG. 9 is a cross-sectional view illustrating a third embodiment of the arrangement of the linear lamp, the reflector, and the diffuser constituting the backlight according to the present invention.

FIG. 10 is a cross-sectional view for explaining a fourth embodiment of the arrangement of the linear lamp, the reflector and the diffuser constituting the backlight according to the present invention.

FIG. 11 is an external view showing an example of a display monitor on which the liquid crystal display device according to the present invention is mounted.

FIG. 12 is a configuration diagram illustrating an example of a peripheral circuit of the liquid crystal display device according to the present invention.

FIG. 13 is a schematic diagram illustrating a conventional liquid crystal display device provided with a direct backlight.

FIG. 14 is a plan view of a light source included in the backlight shown in FIG.

FIG. 15 is a schematic diagram illustrating the installation state of a linear lamp and a difference in brightness between a high-pressure side and a low-pressure side.

[Explanation of symbols]

Reference Signs List 1 lower transparent substrate 1 'upper transparent substrate 2 liquid crystal layer 3 lower polarizing plate 3' upper polarizing plate 4 optical sheet such as prism sheet 5 reflector 6a, 6a ', 6b, 6b', 6c, 6c ', 6d, 6
d ', 6e, 6e', 6f, 6f 'Linear lamp 7 Diffusion plate 8 Light source.

──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. ⁶ Identification code FI G09F 9/00 332 G09F 9/00 332C 333 333Z 336 336G

Claims (5)

[Claims] 1. A liquid crystal panel having a liquid crystal layer sandwiched between a pair of transparent substrates having a pixel selection electrode on at least one of them opposed to each other, a lower polarizing plate arranged with the liquid crystal panel interposed therebetween, and A liquid crystal display device comprising: an upper polarizing plate; a driving unit for applying a voltage according to a display signal to the electrode; and an illumination light source for illuminating the liquid crystal panel from the back. A liquid crystal display device, comprising: a light source having a plurality of linear lamps arranged in parallel with the back surface of the liquid crystal panel as a set of two or more parallelly arranged side-by-side. 2. The illumination light source according to claim 1, wherein the plurality of linear lamps includes:
The liquid crystal display according to claim 1, further comprising: a light source including a reflector provided below the plurality of linear lamps; and a diffusion plate provided above the plurality of linear lamps. apparatus. 3. The reflector has a plurality of concavo-convex structures along the longitudinal direction of the linear lamp, and the set of linear lamps is arranged in each of the concave portions of the concavo-convex structure. The liquid crystal display device according to claim 2. 4. A high-voltage side and a low-voltage side of each of adjacent linear lamps of adjacent linear recesses of a set of linear lamps arranged in each of adjacent concave portions of the plurality of uneven structures. The liquid crystal display device according to claim 3. 5. The apparatus according to claim 2, wherein said diffusion plate has a diffusion pattern or a reflection pattern immediately above each set of linear lamps constituting said light source for uniformizing an illumination light distribution by said linear lamps. 3. The liquid crystal display device according to 1.