JPH10170915A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal display device that can suppress the generation of bright lines with a constitution which is simple, and advantageous for reducing the thickness and the weight by providing the coloring means, which increasees its light absorbing rate as the temperature rises, in the vicinity of at least one of the top or the bottom surfaces of the light transmission body located near a light source (a fluorescent tube). SOLUTION: A coloring dot printing section 1 is provided on the top surface of a reflection sheet 38 located in the vicinity of a fluorescent tube 36 of a light transmission body 37. The section 1 is the coloring means in which the kinds of colors and the light absorbing rate such as color degree of brightness (density) are increased as the temperature rises. Thus, the excessive light beams, which generate bright lines, are absorbed by the section 1 over the period defined by the turn-on of the tube 36 to few hours after a continuous operation during which the temperature rises from room temperature to approximately 80 deg.C. Note that the section 1 changes its color from a light gray to black as the temperature rises from room temperature to approximately 80 deg.C and changes its color from black to light gray as the temperature is reduced to room temperature by utilizing reversible ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called edge-light type back light having a linear light source disposed in the vicinity of a side surface of a light guide along the side surface, and a lamp reflecting sheet covering the linear light source over its entire length. The present invention relates to a liquid crystal display device having a light disposed below a liquid crystal display element.

[0002]

2. Description of the Related Art A liquid crystal display device (that is, a liquid crystal display module) is, for example, arranged such that a display pixel electrode made of a transparent conductive film and an alignment film are laminated on each other with a predetermined gap between them. A transparent insulating substrate made of glass or the like is overlapped, and both substrates are bonded together by a sealing material provided in a frame shape in the vicinity of the peripheral portion between the two substrates, and both of the substrates are inserted through a liquid crystal sealing opening provided in a part of the sealing material. A liquid crystal display element (ie, a liquid crystal display panel, LCD: Liquid Crystal Display (Li) in which a liquid crystal is sealed and sealed inside a sealing material between the substrates and a polarizing plate is further provided outside the two substrates.
quid Crystal Display)), a backlight arranged below the liquid crystal display element to supply light to the liquid crystal display element, a liquid crystal drive circuit board arranged outside the outer periphery of the liquid crystal display element, and each of these members , And a metal frame that houses these members and has a display window opened.

A backlight is, for example, a light guide made of a transparent acrylic or other synthetic resin plate for guiding light emitted from a light source to a direction distant from the light source and uniformly irradiating the entire liquid crystal display element with light. A fluorescent tube, which is a linear light source disposed in the vicinity of the side surface of the light guide along and parallel to the side surface, and covering the fluorescent tube over substantially the entire length thereof, and having a substantially U-shaped cross section.
A lamp reflection sheet having a white or silver color inside surface, a diffusion sheet arranged on the light guide and diffusing light from the light guide, and one or two sheets arranged on the diffusion sheet It is composed of a lens sheet (also referred to as a prism sheet) for improving luminance and a reflection sheet disposed below the light guide and reflecting light from the light guide toward the liquid crystal display element.

[0004] Light incident on the light guide from the fluorescent tube is guided while totally reflecting the light inside the light guide. However, the light is emitted from the upper surface of the light guide by diffuse reflection. Has a plurality of dot patterns for light diffusion printed with white ink, and convex portions and concave portions integrally formed on the bottom surface of the light guide are regularly arranged.

[0005] Such a conventional liquid crystal display device includes:
For example, Japanese Patent Publication No. Sho 60-19474 and Japanese Utility Model Laid-Open No. 4-22
780.

[0006]

FIG. 13A is a front view of a conventional liquid crystal display module, FIG. 13B is a front view of a conventional recent liquid crystal display module, and FIG. FIG. 9 is a view showing a fluorescent tube, a light guide, a liquid crystal display element, and a bright line in a conventional liquid crystal display module.

In FIGS. 1A and 1B, 63 is a liquid crystal display module, 41 is a metal frame (that is, a shield case), 80 is a display window, and 62 is a liquid crystal display element. In (c), 36 is a cold cathode fluorescent tube, 37 is a light guide, 65 is a light incident side surface (light incident end face) of the light guide 37, and 81 is a bright line.

In the recent liquid crystal display module 63, both the enlargement of the screen (that is, the enlargement of the effective display area of the liquid crystal display element) and the miniaturization of the module are achieved.
Therefore, there is a tendency to reduce the so-called frame portion around the display window 80 (that is, to reduce the distance d ₁ in FIG. 13B). the outermost display element (i.e., the fluorescent tube 36 side) the distance d ₂ to the pixels of, for example, that conventionally was several 10mm~10 few mm, has become very narrow and 3.3 mm. That is, the end of the display window 80 and the fluorescent tube 36 are very close to each other.

Therefore, when the fluorescent tube 36 disposed near the light incident side surface 65 of the light guide 37 along the light incident side surface 65 is continuously turned on (that is, when the liquid crystal display module 6 is turned on).
3, that is, when a personal computer or a word processor or the like incorporating the liquid crystal display module 63 as a display unit is used). When the initial lighting of the fluorescent tube 36 is compared with that after 30 minutes to several hours of continuous lighting, the fluorescent tube 36 The temperature rises from room temperature to about 80 ° C. Therefore, due to the influence of the heat generation, the liquid crystal display element 62 becomes hot only in the vicinity of the fluorescent tube 36, and the screen near the end of the display window 80 near the fluorescent tube 36, as shown in FIG. 36, which is referred to as a “bright line” (also referred to as a “color loss” on a color display screen),
There is a problem that the bright line 81 occurs.

In order to prevent the generation of the bright line 81, the area near the fluorescent tube 36 of the diffusion sheet disposed above the light guide 37 or the reflection sheet disposed below the light guide 37 is provided. Alternatively, the present inventors have proposed printing a single color dot with black ink (see Japanese Patent Application No. 7-45348). Further, according to the experiments by the present inventors, in the initial stage of lighting the fluorescent tube 36 (temperature of the fluorescent tube 36: room temperature), a light gray dot is optimal, and after 30 minutes to several hours of continuous lighting (the fluorescent tube 36 is turned on). (Temperature: about 80 ° C.), black dots have been found to be optimal. However, at both temperatures, ie, the fluorescent tube 36
In the process of increasing the temperature from room temperature to about 80 ° C., it was difficult to take measures against the generation of the bright line 81.

An object of the present invention is to provide a liquid crystal capable of effectively suppressing the occurrence of bright lines on a screen near a light source and improving display quality over the initial period of lighting of a backlight and continuous lighting for several hours. A display device is provided.

Another object of the present invention is to provide a simple and thin type.
It is an object of the present invention to provide a liquid crystal display device capable of effectively suppressing the generation of the bright line with a configuration advantageous for weight reduction.

[0013]

In order to achieve the above object, the present invention provides a liquid crystal display device, a light guide disposed under the liquid crystal display device, and a light guide near at least one side of the light guide. A liquid crystal display device comprising a linear light source arranged along the line, and a lamp reflecting sheet covering the linear light source over substantially the entire length thereof, in the vicinity of at least one of the upper surface and the lower surface of the light guide near the linear light source. In addition, a coloring means for increasing the light absorptance due to an increase in temperature is provided.

A liquid crystal display element, a light guide disposed under the liquid crystal display element, a linear light source disposed in the vicinity of at least one side of the light guide along the side, and light from the light guide. Diffusing means disposed on the upper surface of the light guide for diffusing light and irradiating the liquid crystal display element, and the light guide for reflecting light from the light guide and irradiating the liquid crystal display element In a liquid crystal display device comprising a reflecting means disposed on the lower surface of the light source and a lamp reflecting sheet covering the linear light source over substantially the entire length thereof, the diffusing means, at least one of the reflecting means, near the linear light source, It is characterized in that coloring means for increasing the light absorptance by increasing the temperature is provided.

A liquid crystal display element, a light guide disposed below the liquid crystal display element, a linear light source disposed near and along at least one side surface of the light guide, and the linear light source is substantially In a liquid crystal display device comprising a lamp reflecting sheet covering the entire length, a temperature lowering portion is provided between a lower surface of an end portion of the lamp reflecting sheet disposed on an upper surface of the light guide and the upper surface of the light guide. It is characterized in that a coloring means whose light absorptance is increased by the rise is formed.

Also, a liquid crystal display element, a light guide disposed below the liquid crystal display element, a linear light source disposed near and along at least one side of the light guide, and light from the light guide. A diffusion sheet disposed on the upper surface of the light guide to irradiate the liquid crystal display element with light, and covering the linear light source over substantially the entire length thereof; A liquid crystal display device comprising: a lamp reflecting sheet disposed at a position between the lower surface of an end portion of the diffusion sheet near the linear light source and the upper surface of the light guide; A coloring means for increasing the rate is formed.

[0017] Further, the invention is characterized in that the diffusion sheet is not adhered to the light guide, or that an air layer exists between the diffusion sheet and the light guide.

Also, a liquid crystal display element, a light guide disposed under the liquid crystal display element, a linear light source disposed near and along at least one side surface of the light guide, and the linear light source is substantially In a liquid crystal display device including a lamp reflecting sheet covering the entire length, the lamp reflecting sheet includes both ends of the lamp reflecting sheet provided near the upper surface and the lower surface of the light guide, and the upper surface and the lower surface of the light guide. At least one of them is characterized by forming a coloring means whose light absorptance increases as the temperature rises.

Further, the coloring means is a plurality of colored dots formed by printing.

Further, the colored dots are formed so that the printing area gradually decreases from a portion closer to the linear light source to a portion farther from the linear light source.

The colored dots are arranged in a plurality of straight lines substantially parallel to the long axis direction of the linear light source, and are arranged in an arbitrary straight line substantially parallel to the long axis direction of the linear light source. The center points of the plurality of dots are arranged at a substantially middle point between the center points of the plurality of dots arranged linearly before and after the arbitrary straight line.

Further, the coloring means is a colored tape.

Experiments have shown that light gray is optimal at room temperature at the beginning of cold cathode fluorescent tube lighting, and optimal at about 80 ° C. after several hours of continuous lighting. However, heretofore, there has been no good plan. For example, dots for light absorption are printed in an area near a linear light source on a reflection sheet or a diffusion sheet in gray of medium brightness.

In the present invention, the coloring means for increasing the light absorption according to the temperature rise of the light source is provided near the upper surface or the lower surface of the light guide near the linear light source. In this way, it is possible to achieve both countermeasures against the occurrence of bright lines on the screen near the light source that degrades the display quality.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 1A is a perspective view of a backlight disposed below a liquid crystal display element according to Embodiment 1 of the present invention, FIG. 1B is a side view thereof, and FIG. It is a principal part top view of the reflection sheet shown. In the drawings described below, those having the same functions are denoted by the same reference numerals, and the description thereof will not be repeated.

Reference numeral 62 denotes a liquid crystal display element, 37 denotes a wedge-shaped (a trapezoidal side surface) light guide disposed below the liquid crystal display element 62,
65 is a light incident side surface of the light guide 37, 36 is a fluorescent tube arranged along the light incident side 65 near the light incident side 65 of the light guide 37, 66 covers the fluorescent tube 36 over substantially the entire length thereof,
A lamp reflection sheet having a substantially U-shaped cross section and an inner surface thereof is white or silver, 39 is a diffusion sheet disposed below the liquid crystal display element 62 and above the light guide 37, and 38 is below the light guide 37. The arranged reflection sheet 67 is printed with white ink on the bottom surface of the light guide 37, and a plurality of light diffusing members that emit light guided from the upper surface of the light guide 37 while totally reflecting the inside of the light guide 37. The dot patterns 68 and 69 are respectively a lens sheet (also referred to as a lens film) disposed between the diffusion sheet 39 and the liquid crystal display element 62, and 1 is printed on the upper surface of the reflection sheet 38 near the fluorescent tube 36 of the light guide 37. A colored dot printing portion whose light absorptance increases due to an increase in the temperature formed by the above, 70 is an end portion of the lamp reflection sheet 66, 71 is an adhesive bonding the end portion 70 of the lamp reflection sheet 66 to the upper surface of the light guide 37 Layer, 72 Incident side 65 and the opposite sides, 73
Is a reflective tape provided on the side surface 72, and 74 is an adhesive layer for bonding the reflective tape 73 to the side surface 72.

FIG. 1 (c) is a top view of the reflection sheet 38 of FIG. 1 (a) viewed from the direction of arrow A, and is a diagram showing the colored dot printing unit 1. FIG.

In the present embodiment, as shown in FIG. 1, the upper surface of the reflection sheet 38 near the fluorescent tube 36 of the light guide 37 is
By providing the colored dot printing unit 1 in which the light absorption rate such as the type of color and the lightness (density) of the color increases according to the temperature rise, the fluorescent light after continuous lighting for 30 minutes to several hours from the initial lighting of the fluorescent tube 36 is provided. During the process of raising the temperature of the tube 36 from room temperature to about 80 ° C., the bright dot line (FIG.
The extra light that generates 3 (c), 81) is absorbed, and the generation of bright lines on the screen near the fluorescent tube 36, which degrades the display quality, can be suppressed. It should be noted that the colored dot printing section 1 in the present embodiment has a
Formed using an ink that changes from light gray to black as the temperature rises to ℃ and changes from black to light gray as the temperature rises from about 80 ° C. to room temperature (reversible). .

FIG. 6 is a graph showing the relationship between the temperature (° C.) of the light absorbing material (ink) of the colored dot printing section 1 and the light absorption rate (%) in the present embodiment.

Some types of ink do not show a linear (continuous change) characteristic as shown in FIG. 6 (the light absorption rate changes stepwise). in this case,
To approximate the linear characteristic, dots may be printed using several kinds of inks having different light absorptance change characteristics depending on temperature, or dots may be printed by mixing several kinds of inks. Also, dots may be printed by combining at least one type of ink whose light absorption rate increases with an increase in temperature and at least one type of ink whose light absorption rate does not increase with an increase in temperature. Also, here, the fluorescent tube 3
The colored dot printing unit 1 is provided on the upper surface of the reflection sheet 38 near 6. In addition, the end of the diffusion sheet 39 on the fluorescent tube 36 side is extended to the end of the light guide 37 on the fluorescent tube 36 side, A colored dot printing unit 1 may be provided on the lower surface of the end or the like. These will be described in the following embodiments.

The color of the colored dot printing section 1 can be various colors such as brown, purple, and green, in addition to gray and black. Controlling and optimizing the combination of the shape, size, arrangement, color tone, color density, and ink type of the dot pattern of the colored dot printing unit 1 according to the state of generation of the bright line and the intensity of the bright line level . In the present embodiment, the width w of the colored dot printing unit 1 is, for example, 0.1 to 2
mm. For the dot pattern, round dots that are easy to print are used, and the dots are linearly arranged at the same pitch in the longitudinal direction of the fluorescent tube 36 (referred to as dot in-line). The dots arranged in the axial direction are shifted with respect to adjacent columns so that the dots are difficult to see on the screen, and are located in the middle of each other (referred to as staggered arrangement or triangular arrangement: equilateral triangle,
Place it in an isosceles triangle, etc.). On the side farther from the fluorescent tube 36, the dot printing area is smaller.

Further, here, the reflection sheet 38 is not bonded to the light guide 37, and the light guide 37 and the reflection sheet 3 are not bonded.
8 and an air layer exists. The end 70 of the lamp reflection sheet 66 is adhered to the upper surface of the light guide 37 by an adhesive layer 71. The other end of the lamp reflection sheet 66 is located below the reflection sheet 38, but is not adhered and is not shown, but is suppressed by a frame or the like.
Will be retained. The diffusion sheet 39 is also placed on the light guide 37 and is not bonded. In FIGS. 1A and 1B, the lens sheets 68 and 69 and the liquid crystal display element 62 are shown in a floating state, but the lens sheets 68 and 69 are placed on the diffusion sheet 39 so as to be overlapped. Not glued,
A liquid crystal display element 62 is mounted thereon. The lamp reflection sheet 66 is formed such that the inner surface on the fluorescent tube 36 side is formed in white or silver, and the fluorescent tube 36 is directed to the light incident side surface 65 side of the light guide 37.
Of light is reflected. Although not shown, a reflection tape similar to the reflection tape 73 is adhered to two side surfaces of the light guide 37 perpendicular to the light incident side surface 65.

In a recent liquid crystal display module, both the enlargement of the screen and the miniaturization of the module have been attempted. Therefore, the so-called frame around the display window tends to be reduced. The distance from the light incident side surface 65 of the body 37 to the outermost pixel (the fluorescent tube 36 side) of the liquid crystal display element is, for example, several tens mm to several tens mm in the related art.
It has become very narrow at 3.3 mm, and the end of the display window and the fluorescent tube 36 are very close. For this reason, a bright line was easily generated near the end of the display window, but the present invention could easily solve this problem.

Embodiment 2 FIG. 2 is a side view of a backlight showing Embodiment 2 of the present invention.

In the present embodiment, the end portion 7 of the lamp reflection sheet 66 placed on the upper surface of the light guide 37 near the fluorescent tube 36
A colored dot printing unit 1 whose light absorptance increases due to an increase in temperature as in the first embodiment is provided on the lower surface of the dot 0. Therefore, although the place where the colored dot printing unit 1 is provided is different from that of the first embodiment,
Similarly to the above, it is possible to prevent the bright line from being generated on the screen in the vicinity of the fluorescent tube 36 due to the rise in temperature. The other configuration is the same as that of the first embodiment shown in FIG.

Third Embodiment FIG. 3 is a side view of a backlight showing a third embodiment of the present invention.

In the present embodiment, the end portion 7 of the lamp reflection sheet 66 placed on the upper surface of the light guide 37 near the fluorescent tube 36
A colored tape 2 colored with an ink whose light absorptance increases due to a rise in temperature is adhered to the lower surface of the substrate 0 via an adhesive layer 75 in the same manner as in the first embodiment. That is, in the first and second embodiments, colored dots are printed to prevent the occurrence of bright lines, but in the present embodiment, the colored tape 2 is attached instead. Therefore, similarly to the first and second embodiments, it is possible to prevent the occurrence of bright lines on the screen due to a rise in temperature. The coloring is
It suffices that at least the light guide 37 side, that is, the lower surface is colored, but the lower surface and the upper surface, or the entire color including the inside of the tape may be used. In the second embodiment, the light guide 37 has a flat plate shape (a rectangular parallelepiped shape). However, in the present embodiment, the light guide 37 is the first embodiment.
Similarly, a light guide 37 having a wedge shape (that is, a trapezoidal cross section) was used to reduce the weight and thickness of the liquid crystal display module. Other configurations are the same as those of the first and second embodiments shown in FIGS. In addition, the colored tape 2 has the adhesive layer 7
1 is adhered to the upper surface of the light guide 37.

Fourth Embodiment FIG. 4 is a side view of a backlight showing a fourth embodiment of the present invention.

In the present embodiment, the colored dot printing section 1 whose light absorptance increases as the temperature rises is provided on the lower surface of the diffusion sheet 39 near the fluorescent tube 36. That is, FIG.
In the second embodiment, the colored dot printing unit 1 for preventing the generation of the bright line is provided on the lower surface of the lamp reflection sheet 66 on the light guide 37. Provided on the lower surface. Therefore, similarly to the above embodiments, it is possible to prevent the occurrence of bright lines due to a rise in temperature. The end 70 of the lamp reflection sheet 66 is
It is adhered to the upper surface of the diffusion sheet 39 via the adhesive layer 71. Other configurations are the same as those of the second embodiment shown in FIG.

Fifth Embodiment FIG. 5 is a side view of a backlight showing a fifth embodiment of the present invention.

In the present embodiment, the lower surface of the diffusion sheet 39 in the vicinity of the fluorescent tube 36 of the wedge-shaped light guide 37 is colored with an ink whose light absorptance increases as the temperature rises via the adhesive layer 75. The coloring tape 2 is stuck. Therefore, similarly to the above-described embodiments, the colored tape 2 can prevent the generation of a bright line due to a rise in temperature.
The end portion 70 of the lamp reflection sheet 66 is provided on the upper surface of the diffusion sheet 39 with the adhesive layer 78, the base material layer 76, and the adhesive layer 77.
It is adhered by a double-sided tape 79 made of. Other configurations are the same as those of the third embodiment shown in FIG.

In the first to fifth embodiments, the effect of preventing the emission of a bright line remains unchanged regardless of whether the colored dot printing portion or the colored tape is provided above or below the light guide 37. Also, it may be provided on both sides.

Hereinafter, a liquid crystal display device of a simple matrix system to which the present invention described in the first to fifth embodiments is applicable will be described.

<< Simple Matrix Type Liquid Crystal Display >> FIG.
FIG. 2 is a perspective view of a main part of a liquid crystal display element 62 of a simple matrix type liquid crystal display device to which the present invention can be applied.

In FIG. 7, in order to align the liquid crystal molecules in a twisted helical structure between the two upper and lower electrode substrates 11 and 12 sandwiching the liquid crystal layer 50, a transparent upper layer made of, for example, glass is used. A method in which the surfaces of the alignment films 21 and 22 on the lower electrode substrates 11 and 12 which are in contact with the liquid crystal and are made of, for example, an organic polymer resin made of polyimide, are rubbed in one direction with, for example, a cloth. Have been. The rubbing direction at this time, that is, the rubbing direction, the rubbing direction 6 for the upper electrode substrate 11, and the rubbing direction 7 for the lower electrode substrate 12 are the alignment directions of the liquid crystal molecules. The two upper and lower electrode substrates 1 thus oriented are treated.
1,12 to have a gap d ₁ to the respective rubbing directions 6, 7 intersect at 360 degrees about 180 degrees from each other are opposed to each other, switching for injecting two electrode substrates 11, 12 liquid crystal When a nematic liquid crystal having a positive dielectric anisotropy and a predetermined amount of an optical rotatory substance added thereto is sealed with a frame-shaped sealing material 52 having a notched portion (that is, a liquid crystal filling port) 51, The liquid crystal molecules have a helical molecular arrangement with a twist angle θ in the figure between the electrode substrates. In addition, 31 and 32 are, for example, indium oxide (IT
O: Indium Tin Oxide
Transparent upper and lower electrodes. A member (hereinafter, referred to as a birefringent member) 40 for providing a birefringence effect is disposed above the upper electrode substrate 11 of the liquid crystal cell 60 configured as described above.
Upper and lower polarizing plates 15 and 16 are provided so as to sandwich 0.

The twist angle θ of the liquid crystal molecules in the liquid crystal 50 can have a value in the range of 180 ° to 360 °, and is preferably 200 ° to 300 °. From the practical viewpoint of avoiding a phenomenon in which the lighting state becomes an orientation that scatters light and maintaining excellent time division characteristics, the range of 230 degrees to 270 degrees is more preferable. This condition basically acts to make the response of the liquid crystal molecules to the voltage more sensitive and to realize excellent time division characteristics. In order to obtain excellent display quality, the product Δn of the refractive index anisotropy Δn ₁ of the liquid crystal layer 50 and its thickness d ₁ is used.
₁ · d ₁ is preferably set in the range of 0.5 μm to 1.0 μm, more preferably 0.6 μm to 0.9 μm.

The birefringent member 40 functions to modulate the polarization state of the light transmitted through the liquid crystal cell 60, and converts the liquid crystal cell 60, which could only display in a colored state, into a monochrome display. Thus the birefringent member 40 refractive index anisotropy [Delta] n ₂ and is extremely important product [Delta] n ₂ · d ₂ of a thickness d _2, preferably 0.8μm from 0.4 .mu.m, more preferably 0.5μm Is set in a range from 0.7 μm to 0.7 μm.

Further, since the liquid crystal display element 62 uses elliptically polarized light due to birefringence, the axes of the polarizing plates 15 and 16 and the optical axis when a uniaxial transparent birefringent plate is used as the birefringent member 40. And the electrode substrate 11 of the liquid crystal cell 60,
The relationship between the twelve liquid crystal alignment directions 6 and 7 is extremely important.

However, as shown in FIG.
Red, green, blue color filters 33R, 33G, 33 on top
B. By providing the light shielding film 33D between the filters, multi-color display is possible.

In FIG. 8, each filter 33
On the R, 33G, 33B and the light shielding film 33D, a smooth layer 23 made of an insulator is formed to reduce the influence of these irregularities, and then an upper electrode 31 and an alignment film 21 are formed.

FIG. 9 is an exploded perspective view showing a liquid crystal display element 62, a driving circuit for driving the liquid crystal display element 62, and a liquid crystal display module 63 in which light sources are compactly integrated.

Drive IC 3 for driving liquid crystal display element 62
Reference numeral 4 is provided with a window for fitting the liquid crystal display element 62 at the center, and is mounted on a frame-shaped printed circuit board 35 on which a circuit for driving liquid crystal is formed. The printed circuit board 35 in which the liquid crystal display element 62 is fitted is fitted in a window of a frame 42 made of plastic mold, a metal frame 41 is superimposed on the window, and its claws 43 are formed in the frame 42. The frame 41 is fixed to the frame-shaped body 42 by folding it into the cut 44.

A cold cathode fluorescent tube 36 disposed at the upper and lower ends of the liquid crystal display element 62; a light guide 37 made of an acrylic plate for uniformly irradiating the liquid crystal display cell 60 with light from the cold cathode fluorescent tube 36; A reflecting plate 38 formed by applying a white paint on a metal plate and a milky white diffusing plate 39 for diffusing light from the light guide 37 are fitted into the window of the frame 42 from the back side in the order shown in FIG. It is. An inverter power supply circuit (not shown) for lighting the cold cathode fluorescent tube 36 is provided with a concave portion (not shown, a concave portion 4
5. ). Diffusing plate 3
9, light guide 37, cold cathode fluorescent tube 36 and reflector 38
The tongue piece 46 provided on the reflection plate 38 is
Is fixed by folding it into the fore-edge 47 provided in the front end.

Although illustration is omitted in this figure, it is possible to prevent the occurrence of bright lines on the screen due to a rise in temperature near the light source by applying the above-described embodiments 1 to 5 shown in FIGS. Can be. The liquid crystal display module 6
In FIG. 3, two cold cathode fluorescent tubes 36 are arranged along two opposing sides of the light guide 37 as shown in the figure. .
In this figure, the lamp reflection sheet is not shown.

FIGS. 10 and 11 show a case where the liquid crystal display module 63 shown in FIG. 9 is used for a display section of a laptop personal computer.

FIG. 10 shows a block diagram of the system, and FIG.
The result calculated by the microprocessor 49 is to drive the liquid crystal display module 63 by the driving IC 34 via the control LSI 48.

<< Active Matrix Type Liquid Crystal Display Device >><< Overall Configuration of Liquid Crystal Display Module >> FIG. 12 is an exploded perspective view of the liquid crystal display module MDL.

SHD is a shield case (also called a metal frame) made of a metal plate, WD is a display window, INS1
To 3 are insulating sheets, PCB1 to 3 are circuit boards (PCB1
Is a drain side circuit board, PCB2 is a gate side circuit board,
PCB3 is an interface circuit board), JN is a joiner for electrically connecting the circuit boards PCB1 to PCB3, T
CP1 and TCP2 are tape carrier packages, PNL
Is a liquid crystal display panel, SB is a solar cell, GC is a rubber cushion, ILS is a light shielding spacer, PRS is a prism sheet, SPS is a diffusion sheet, GLB is a light guide plate, RFS is a reflection sheet, and MCA is a lower part formed by integral molding. A case (mold case), LP is a fluorescent tube, LPC is a lamp cable, GB is a rubber bush that supports the fluorescent tube LP, and each member is stacked in a vertical arrangement as shown in FIG. Assembled.

The module MDL includes a lower case MCA,
It has two kinds of storage and holding members for the shield case SHD. Insulating sheets INS1-3, circuit boards PCB1-3,
The liquid crystal display panel PNL is combined with a metal shield case SHD housed and fixed, and a lower case MCA housing a backlight BL including a fluorescent tube LP, a light guide plate GLB, a prism sheet PRS, and the like, so that the module MDL is formed. Assembled.

Although not shown in this figure, it is possible to prevent the occurrence of bright lines on the screen due to a rise in temperature near the light source by applying the above-described embodiments 1 to 5 shown in FIGS. Can be.

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, in the first to fifth embodiments shown in FIGS.
Is bonded to the upper surface of the light guide 37 or the diffusion sheet 39 with an adhesive layer 71 or a double-sided tape 79,
The other end of the lamp reflection sheet 66 is not bonded, but is held down by a frame or the like.
Such a configuration is not necessary. That is, for example, the end 70 of the lamp reflection sheet 66 is suppressed by a frame or a frame of a molded product, and the other end of the lamp reflection sheet 66 is bonded to the reflection sheet 38 or the lower surface of the light guide 37. It may be bonded via an agent layer or the like. Further, the diffusion sheet 39 may be a diffusion plate, and the reflection sheet 39 may be a reflection plate,
It may be one integrated with a frame or the like. Also, FIG.
In the first, second, and fourth embodiments 1, 2, and 4, the colored dot printing unit 1 configured with an array of dots is provided, but the dots having the shape and the array as illustrated in FIG. Of course, it is not necessary. It controls and optimizes the shape, size, arrangement, color tone, and color density of the dot pattern of the colored dot printing unit according to the state and intensity of the bright line generation on the screen. Further, the present invention is not necessarily required to be dot-shaped, and the effect of the present invention can be obtained by performing colored printing. The color of the colored dot printing portion and the color of the colored tape may be gray, dark brown, purple, green, black, or the like. Further, the present invention can be applied to a simple matrix type liquid crystal display device, a vertical electric field type or 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.

[0062]

As described above, according to the present invention,
A simple and advantageous configuration for thinning and lightening allows the generation of bright lines on the screen near the light source due to the temperature rise of the liquid crystal display element due to the heat generated by the light source during the initial period of lighting the backlight and after several hours of continuous lighting. Can be effectively suppressed, and the display quality can be improved.

[Brief description of the drawings]

FIG. 1A is a perspective view of a backlight disposed below a liquid crystal display element according to Embodiment 1 of the present invention, FIG. 1B is a side view thereof, and FIG. This is the main part upper surface part.

FIG. 2 is a side view of a backlight according to a second embodiment of the present invention.

FIG. 3 is a side view of a backlight according to a third embodiment of the present invention.

FIG. 4 is a side view of a backlight according to a fourth embodiment of the present invention.

FIG. 5 is a side view of a backlight according to a fifth embodiment of the present invention.

FIG. 6 is a graph showing a relationship between a temperature (° C.) and a light absorption rate (%) of a colored dot printing section in the embodiment of the present invention.

FIG. 7 shows an example of the relationship among the arrangement direction of liquid crystal molecules, the twist direction of liquid crystal molecules, the direction of the axis of a polarizing plate, and the optical axis of a birefringent member in a liquid crystal display element of a simple matrix liquid crystal display device to which the present invention can be applied. It is the schematic perspective view which showed.

FIG. 8 is a partially cutaway perspective view of an upper electrode substrate portion of another color liquid crystal display element of a simple matrix system.

FIG. 9 is an exploded perspective view of an example of a simple matrix type liquid crystal display module.

FIG. 10 is a block diagram of an example of a laptop personal computer incorporating the liquid crystal display module of FIG. 9;

11 is an external perspective view of an example of a laptop personal computer incorporating the liquid crystal display module of FIG.

FIG. 12 is an exploded perspective view of an example of a liquid crystal display module of an active matrix type color liquid crystal display device to which the present invention can be applied.

13A is a front view of a conventional liquid crystal display module, FIG. 13B is a front view of a conventional recent liquid crystal display module, and FIG. 13C is a fluorescent tube in the conventional liquid crystal display module shown in FIG. FIG. 3 is a diagram showing a light guide, a liquid crystal display element, and a bright line.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Colored dot printing part, 2 ... Colored tape, 36 ... Fluorescent tube, 37 ... Light guide, 38 ... Reflection sheet, 39 ... Diffusion sheet, 41 ... Metal frame, 62 ... Liquid crystal display element, 63
... Liquid crystal display module, 65 ... Light incident side of light guide, 66
... lamp reflection sheet, 67 ... dot pattern for light diffusion,
68, 69: lens sheet, 70: end of lamp reflection sheet, 71, 74, 75, 77, 78: adhesive layer, 72
... Side surface of light guide, 73. Reflective tape, 76.
9: double-sided tape, 80: display window, 81: bright line.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Naohiro Shino 3350 Hayano, Mobara-shi, Chiba Prefecture Within Hitachi Electronics Devices Corporation (72) Inventor Seiichi Nishiyama 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd. Hitachi Electronics Co., Ltd. Inside the company

Claims (10)

[Claims] 1. A liquid crystal display element, a light guide disposed under the liquid crystal display element, a linear light source disposed near and along at least one side surface of the light guide, and the linear light source is substantially A liquid crystal display device comprising: a lamp reflecting sheet covering the entire length; and a coloring means for increasing a light absorptance due to a rise in temperature, near at least one of an upper surface and a lower surface of the light guide near the linear light source. A liquid crystal display device characterized by the above-mentioned. 2. A liquid crystal display element, a light guide disposed thereunder, a linear light source disposed near and along at least one side of the light guide, and light from the light guide. Diffusing means disposed on the upper surface of the light guide for diffusing light and irradiating the liquid crystal display element, and the light guide for reflecting light from the light guide and irradiating the liquid crystal display element In a liquid crystal display device comprising a reflecting means disposed on the lower surface of the light source and a lamp reflecting sheet covering the linear light source over substantially the entire length thereof, the diffusing means, at least one of the reflecting means, near the linear light source, A liquid crystal display device comprising a coloring means for increasing a light absorption rate with a rise in temperature. 3. A liquid crystal display element, a light guide disposed thereunder, a linear light source disposed near at least one side surface of the light guide along the side surface, and the linear light source is substantially In a liquid crystal display device comprising a lamp reflecting sheet covering the entire length, a temperature lowering portion is provided between a lower surface of an end portion of the lamp reflecting sheet disposed on an upper surface of the light guide and the upper surface of the light guide. A liquid crystal display device comprising a coloring means for increasing the light absorptance by the rise. 4. A liquid crystal display element, a light guide disposed under the liquid crystal display element, a linear light source disposed near and along at least one side of the light guide, and light from the light guide. A diffusion sheet disposed on the upper surface of the light guide to irradiate the liquid crystal display element with light, and covering the linear light source over substantially the entire length thereof; A liquid crystal display device comprising: a lamp reflecting sheet disposed at a position between the lower surface of an end portion of the diffusion sheet near the linear light source and the upper surface of the light guide; A liquid crystal display device comprising a coloring means for increasing the rate. 5. The liquid crystal display according to claim 4, wherein the diffusion sheet is not bonded to the light guide, or an air layer exists between the diffusion sheet and the light guide. apparatus. 6. A liquid crystal display element, a light guide disposed under the liquid crystal display element, a linear light source disposed near and along at least one side surface of the light guide, and the linear light source is substantially In a liquid crystal display device including a lamp reflecting sheet covering the entire length, the lamp reflecting sheet includes both ends of the lamp reflecting sheet provided near the upper surface and the lower surface of the light guide, and the upper surface and the lower surface of the light guide. A liquid crystal display device characterized in that at least one of them has a coloring means for increasing the light absorption rate as the temperature rises. 7. A method according to claim 1, wherein said coloring means is a plurality of colored dots formed by printing.
7. The liquid crystal display device according to 3, 4 or 6. 8. The liquid crystal display device according to claim 7, wherein the colored dots are formed such that a printing area gradually decreases from a portion closer to the linear light source to a portion farther from the linear light source. 9. The colored dots are arranged in a plurality of straight lines substantially parallel to the long axis direction of the linear light source, and are arranged in an arbitrary straight line substantially parallel to the long axis direction of the linear light source. 8. The liquid crystal display according to claim 7, wherein the center points of the plurality of dots are arranged at substantially the middle points of the center points of the plurality of dots arranged linearly before and after the arbitrary straight line. apparatus. 10. The liquid crystal display device according to claim 1, wherein said coloring means is a coloring tape.