JPH07261173A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide an inexpensive liquid crystal display device of high reliability capable of holding a light transmission plate in a case by having a simple structure, and capable of reducing the cost of the light transmission plate by unnecessitating the working process and working cost of a hole and a notch in the light transmission plate. CONSTITUTION:The rectangular light transmission plate 2 and a fluorescent lamp 3 arranged near the side of the plate 2 are contained in an integrally molded mold case 4, the light transmission plate 2 is prevented from moving toward the fluorescent lamp 3 by two stoppers 1 which are integrally molded with the mold case 4 so as to come into contact with one side near the lamp 3 of the plate 2 and also which are made lower than the thickness of the light transmission plate 2, and also, three remaining sides of the light transmission plate 2 are held by the inner wall of the mold case 4 molded along the shape of the plate 2.

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 having a backlight which includes a light guide plate disposed below a liquid crystal display element and a fluorescent tube disposed near the side surface of the light guide plate.

[0002]

2. Description of the Related Art In a liquid crystal display device, for example, two transparent glass substrates are superposed on each other at a predetermined interval so that surfaces on which a pixel electrode made of a transparent conductive film and an alignment film are laminated face each other. A liquid crystal display element (liquid crystal display panel) formed by bonding both substrates with each other by a sealing material provided around the edge between the substrates, sealing the liquid crystal between the two substrates, and further providing a polarizing plate outside the both substrates. The backlight is arranged below the liquid crystal display element and supplies a light to the liquid crystal display element, and includes a circuit board for driving the liquid crystal display element.

The backlight includes, for example, a light guide plate made of a transparent synthetic resin plate for guiding the light emitted from the light source to the side away from the light source and uniformly irradiating the light on the entire liquid crystal display element, and the light guide plate. A fluorescent tube, which is a light source disposed near the side surface along the side surface, a lamp reflection sheet that covers the fluorescent tube over substantially the entire length thereof, has a substantially U-shaped cross section, and returns the light of the fluorescent tube to the light guide plate. The diffusion sheet is disposed on the light plate and diffuses the light from the light guide plate, and the reflection sheet is disposed under the light guide plate and reflects the light from the light guide plate toward the liquid crystal display element.

Such a conventional liquid crystal display device is disclosed, for example, in Japanese Examined Patent Publication No. Sho 60-19474 and Japanese Utility Model Laid-Open No. 4-22780.
It is described in Japanese Patent Publication No.

[0005]

Problems to be Solved by the Invention FIGS. 13 (a) and 13 (b)
FIG. 3 is a plan view of a mold case accommodating a light guide plate and a fluorescent tube of the conventional liquid crystal display devices of the first and second examples, respectively.

Reference numeral 2 is a light guide plate disposed under the liquid crystal display element, 3 is a fluorescent tube disposed near the side surface of the light guide plate 2, 4 is a light guide plate 2, and the fluorescent tube 3 is formed by integral molding. It is a plastic molded case.

In the conventional liquid crystal display device of the first example, the shape of the light guide plate 2 is as shown in FIG. 13A in order to hold the light guide plate 2 in the mold case 4, that is,
It had a shape with two rectangular corners cut. Reference numeral 65 is a notch in the light guide plate 2. The shape of the inner wall of the molded case 4 is formed to match the shape of the light guide plate 2, holds the light guide plate 2, and prevents the light guide plate 2 from moving toward the fluorescent tube 3 and damaging the fluorescent tube 3. Has become.

In the conventional liquid crystal display device of the second example, the shape of the light guide plate 2 is rectangular, but in order to fix the light guide plate 2 in the mold case 4, as shown in FIG. A hole 66 is provided in the light guide plate 2 (two holes may be provided in some cases), and the light guide plate 2 is fastened with a screw (not shown).

However, in the conventional liquid crystal display device as described above, the corners of the rectangular light guide plate 2 are cut to form the notches 65, or the holes 66 are drilled to process the holes. There was a problem of this.
Further, since the light guide plate 2 is provided with the notch 65 and the hole 66,
There is a problem that the in-plane luminance distribution of the light guide plate 2 becomes non-uniform, and it becomes difficult to design the light guide plate (specifically, the design of the dot pattern on the bottom surface of the light guide plate) for making the brightness uniform.

An object of the present invention is to provide a liquid crystal display device having a light guide plate which is inexpensive and has a uniform in-plane luminance distribution.

[0011]

In order to solve the above-mentioned problems, the present invention provides a light guide plate disposed below a liquid crystal display element, and a fluorescent tube arranged near the side face of the light guide plate and along the side face. In a liquid crystal display device in which and are housed in a case, the light guide plate has a substantially rectangular shape, and by a stopper provided in contact with one side of the light guide plate on the fluorescent tube side or in the vicinity of the one side, It is characterized in that the movement of the light guide plate toward the fluorescent tube side is prevented, and the remaining three sides of the light guide plate are held by the inner wall of the case formed along the shape of the light guide plate.

Further, the case is a molded case formed by integral molding.

Further, the stopper is provided integrally with the case.

Further, the height of the stopper is smaller than the thickness of the light guide.

[0015]

In the liquid crystal display device of the present invention, since the light guide plate can be held in the case without providing mounting holes and holding notches, it is possible to perform processing for forming holes and notches. The cost of the light guide plate can be reduced because the process and processing costs are unnecessary.

By providing the stopper of the light guide plate integrally with the mold case formed by integral molding, the stopper can be easily formed.

Further, by making the height of the stopper smaller than the thickness of the light guide, the rate of hindering the incidence of light from the fluorescent tube, which is the light source, on the light guide plate is reduced as compared with the prior art. The in-plane luminance distribution of the light plate can be made uniform, and the luminance of the light guide plate can be improved.

[0018]

【Example】

Example 1 FIG. 1 (a) is a plan view of a light guide plate of a liquid crystal display device of Example 1 of the present invention and a mold case accommodating a fluorescent tube, (b).
Is a cross-sectional view taken along the line bb of (a), (c) is a cross-sectional view taken along the line cc of (a), and (d) is a perspective view of a main part (a fluorescent tube is not shown).

Reference numeral 2 denotes a liquid crystal display element (not shown; see FIG. 7).
A light guide plate 3 disposed underneath, a fluorescent tube 3 arranged near the side surface of the light guide plate 4, a plastic molded case 4 for accommodating the light guide plate 2 and the fluorescent tube 3 formed by integral molding, 1
Is a stopper of the light guide plate 2.

In this embodiment, as shown in FIG. 1, the light guide plate 2 has a quadrangular shape (rectangular shape). The fluorescent tube 3 of the light guide plate 2 is provided by the two stoppers 1 provided integrally with the mold case 4 so as to contact one side of the light guide plate 2 on the fluorescent tube 3 side.
This prevents the fluorescent tube 3 from being damaged and prevents the fluorescent tube 3 from being damaged. The remaining three sides of the light guide plate 2 are held by the inner wall of the molded case 4 formed along the shape of the light guide plate 2. The height of the stopper 1 is the same as or slightly larger than the thickness of the light guide 2.

In the liquid crystal display device of this embodiment, the light guide plate 2 can be held in the mold case 4 without providing a mounting hole or a holding notch, so that the hole or notch is formed. Since the processing step and processing cost for doing so are unnecessary, the light guide plate 2 can be manufactured at low cost. Further, by providing the stopper 1 integrally with the molded case 4 formed by integral molding, the stopper can be easily formed, and the holding structure of the light guide plate 2 can be easily realized. Therefore, the manufacturing cost of the liquid crystal display device can be reduced, and a highly reliable and inexpensive liquid crystal display device can be provided.

Embodiment 2 FIG. 2 (a) is a plan view of a light guide plate of a liquid crystal display device according to Embodiment 2 of the present invention and a mold case accommodating a fluorescent tube, (b).
Is a cross-sectional view taken along the line bb of (a), (c) is a cross-sectional view taken along the line cc of (a), and (d) is a perspective view of a main part (a fluorescent tube is not shown).

Also in this embodiment, as shown in FIG.
The two triangular prism-shaped stoppers 1 provided integrally with the mold case 4 so as to be in contact with one side of the light guide plate 2 on the side of the fluorescent tube 3 prevent the light guide plate 2 from moving toward the side of the fluorescent tube 3 to prevent fluorescence. Damage to the tube 3 is prevented. The remaining three sides of the light guide plate 2 are held by the inner wall of the molded case 4 formed along the shape of the light guide plate 2. In this embodiment, the height of the stopper 1 is smaller than the thickness of the light guide 2.

In this embodiment, in addition to the effects of the first embodiment,
Since the height of the stopper 1 is smaller than the thickness of the light guide 2, the rate of hindering the incidence of light from the fluorescent tube 3 onto the light guide plate 2 is reduced as compared with the prior art, so that the in-plane brightness of the light guide plate 2 is reduced. The distribution can be made uniform, and the brightness of the light guide plate 2 can be improved. Therefore, the dot pattern of the light guide plate can be easily designed, and the manufacturing cost can be reduced. It should be noted that the positions where the two stoppers 1 are provided are preferably at both ends as shown in FIG. 2 (same in the first embodiment) from the viewpoint of uniforming the luminance distribution of the light guide plate 2.

In the first and second embodiments, the stopper 1
Two are provided, but only one may be provided, for example, in the center.
Further, the shape of the stopper 1 is not limited to the first and second embodiments, and various shapes can be formed.

FIG. 3 is an overall perspective view of the liquid crystal display device according to the present invention.

FIG. 4 is a block diagram of a laptop personal computer using the liquid crystal display module 63 for the display section, and FIG. 5 is a diagram showing a state in which the liquid crystal display module 63 is mounted on the laptop personal computer 64. In this laptop personal computer 64, the microprocessor 49
The liquid crystal display module 63 is driven by the liquid crystal driving semiconductor IC 34 via the control LSI 48 via the control LSI 48.

FIG. 6 shows an arrangement direction of liquid crystal molecules on an electrode substrate (for example, a rubbing direction), a twisting direction of liquid crystal molecules, a polarizing plate when a liquid crystal display element 62 of a liquid crystal display device to which the present invention is applied is viewed from above. Polarization axis (or absorption axis) of
Direction and the optical axis direction of the member that brings about the birefringence effect, and FIG. 7 is a perspective view of a main part of the liquid crystal display element 62.

Twisting direction 10 of liquid crystal molecules and twist angle θ
Is a rubbing direction 6 of the alignment film 21 on the upper electrode substrate 11, a rubbing direction 7 of the alignment film 22 on the lower electrode substrate 12, and a positive dielectric anisotropy sandwiched between the upper electrode substrate 11 and the lower electrode substrate 12. It is defined by the type and amount of the optical rotatory substance added to the nematic liquid crystal layer 50 having the property.

In FIG. 7, in order to align the liquid crystal molecules between the two upper and lower electrode substrates 11 and 12 sandwiching the liquid crystal layer 50 so as to have a twisted spiral structure, a transparent upper layer made of, for example, glass is used. The rubbing method, which is a method of rubbing the surfaces of the alignment films 21 and 22 made of an organic polymer resin made of polyimide, for example, in contact with the liquid crystal on the lower electrode substrates 11 and 12 with a cloth in one direction, is used. ing. The rubbing direction at this time, that is, the rubbing direction, the rubbing direction 6 in the upper electrode substrate 11, and the rubbing direction 7 in the lower electrode substrate 12 are the alignment directions of the liquid crystal molecules. The two upper and lower electrode substrates 1 that have been oriented in this way
1 and 12 are made to face each other with a gap d ₁ so that the rubbing directions 6 and 7 intersect each other at approximately 180 to 360 degrees, and the two electrode substrates 11 and 12 are notched for injecting liquid crystal. That is, when a nematic liquid crystal having a positive dielectric anisotropy and having a predetermined amount of an optical rotatory substance is sealed by adhering with a frame-shaped sealing material 52 having a liquid crystal sealing port 51, liquid crystal molecules Has a helical molecular arrangement with a twist angle θ in the figure between the electrode substrates. Incidentally, 31 and 32 are, for example, indium oxide or ITO, respectively.
(Indium Tin Oxide) transparent upper and lower electrodes. A member for producing a birefringence effect on the upper electrode substrate 11 of the liquid crystal cell 60 thus configured (hereinafter referred to as a birefringence member. Fujimura et al., "STN-LCD retardation film", magazine electronic material 1991 2 (Month issue, pages 37-41)
40 is provided, and upper and lower polarizing plates 15 and 16 are provided with the member 40 and the liquid crystal cell 60 sandwiched therebetween.

The twist angle θ of the liquid crystal molecules in the liquid crystal 50 can take a value in the range of 180 ° to 360 °, but is preferably 200 ° to 300 °, but lighting in the vicinity of the threshold value of the transmittance-applied voltage curve. From the practical viewpoint of avoiding the phenomenon that the state becomes an orientation that scatters light and maintaining excellent time division characteristics, the range of 230 to 270 degrees is more preferable. This condition basically makes the response of the liquid crystal molecules to the voltage more sensitive and acts to realize excellent time division characteristics. In order to obtain excellent display quality and the refractive index anisotropy [Delta] n ₁ of the liquid crystal layer 50 a product [Delta] n ₁ of the thickness d 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 acts so as to modulate the polarization state of the light passing through the liquid crystal cell 60, and converts what could be displayed only in the liquid crystal cell 60 alone into a black and white 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 To 0.7 μm.

Further, since the liquid crystal display element 62 uses the elliptically polarized light due to the birefringence, the axes of the polarizing plates 15 and 16 and the optical axis when the 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 liquid crystal alignment directions 12 and 6 is extremely important.

The effect of the above relationship will be described with reference to FIG. FIG. 6 shows an axis of a polarizing plate, an optical axis of a uniaxial transparent birefringent member when the liquid crystal display device having the configuration of FIG. 7 is viewed from above,
3 shows the relationship between the alignment directions of liquid crystal molecule axes of an electrode substrate of a liquid crystal cell.

In FIG. 7, 5 is the optical axis of the uniaxial transparent birefringent member 40, 6 is the alignment direction of the liquid crystal molecules of the birefringent member 40 and the upper electrode substrate 11 adjacent thereto, and 7 is the lower electrode substrate 12. The liquid crystal alignment direction, 8 is the absorption axis or polarization axis of the upper polarization plate 15, 9 is the absorption axis or polarization axis of the lower polarization plate 16, and the angle α is uniaxial birefringence with the liquid crystal alignment direction 6 of the upper electrode substrate 11. The angle β formed by the optical axis 5 of the member 40 is the angle formed by the absorption axis or polarization axis 8 of the upper polarizing plate 15 and the optical axis 5 of the uniaxial transparent birefringent member 40, and the angle γ is the lower polarizing plate 16. Is the angle between the absorption axis or polarization axis 9 of the liquid crystal and the liquid crystal alignment direction 7 of the lower electrode substrate 12.

Here, how to measure the angles α, β, and γ in this specification will be defined. In FIG. 11, the intersection angle between the optical axis 5 of the birefringent member 40 and the liquid crystal alignment direction 6 of the upper electrode substrate will be described as an example. The intersection angle between the optical axis 5 and the liquid crystal alignment direction 6 can be represented by φ ₁ and φ ₂ , as shown in FIG. 11, but in this specification, the smaller angle of φ ₁ and φ ₂ is adopted. That is, in FIG. 11A, φ ₁ <φ ₂
Since it is, the phi ₁ and the crossing angle α between the optical axis 5 and the liquid crystal alignment direction 6, and the intersection angle α between φ _1> φ ₂ So the optical axis 5 of phi ₂ liquid crystal alignment direction 6 in FIG. 11 (b) To do. Of course φ ₁
In the case of = φ ₂ , either one may be adopted.

In the liquid crystal display device, the angles α, β and γ are extremely important.

The angle α is preferably 50 to 90 degrees, more preferably 70 to 90 degrees, the angle β is preferably 20 to 70 degrees, more preferably 30 to 60 degrees, and the angle γ is preferably. It is desirable to set each to 0 to 70 degrees, and more preferably to 0 to 50 degrees.

If the twist angle θ of the liquid crystal layer 50 of the liquid crystal cell 60 is in the range of 180 ° to 360 °, the above angle is satisfied regardless of whether the twist direction 10 is clockwise or counterclockwise. α, β, and γ may be within the above range.

In FIG. 7, the birefringent member 40 is disposed between the upper polarizing plate 15 and the upper electrode substrate 11, but instead of this position, the lower electrode substrate 12 and the lower polarizing plate 16 are provided.
It may be disposed between and. This case corresponds to the case where the entire configuration of FIG. 7 is inverted.

FIG. 8 is a diagram showing a specific example of the twist angle θ and the like. As shown in the figure, the twist angle θ of the liquid crystal molecules is 240 degrees, and as the uniaxial transparent birefringent member 40, a liquid crystal cell having a parallel orientation (homogeneous orientation), that is, a twist angle of 0 degree was used. Here, the thickness d (μm) of the liquid crystal layer and the helical pitch p (μ of the liquid crystal material added with the optical rotatory substance)
The ratio d / p of m) was set to 0.67. Alignment films 21 and 22
Was used, which was formed of a polyimide resin film and rubbed. The tilt angle (pretilt angle) at which the alignment film subjected to the rubbing process causes the liquid crystal molecules in contact with the alignment film to be tilted with respect to the substrate surface is 4 degrees. The Δn ₂ · d ₂ of the uniaxial transparent birefringent member 40 is about 0.6 μm. On the other hand, Δn ₁ · of the liquid crystal layer 50 in which the liquid crystal molecules are twisted by 240 degrees
d ₁ is about 0.8 μm.

At this time, by setting the angle α to about 90 degrees, the angle β to about 30 degrees, and the angle γ to about 30 degrees, the voltage applied to the liquid crystal layer 50 via the upper and lower electrodes 31 and 32 is increased. When the voltage is below the threshold value, light non-transmission, that is, black display, and when the voltage exceeds a threshold value, light transmission, that is, white and black display, can be realized. In addition, the axis of the lower polarizing plate 16 is 50
When rotated 90 degrees from 90 degrees, white display was realized when the voltage applied to the liquid crystal layer 50 was below the threshold value, and black when the voltage was above the threshold value, which was the reverse of the above.

FIG. 9 shows a change in contrast during time-division driving at 1/200 duty when the angle α is changed in the configuration of FIG. Although the contrast was extremely high when the angle α was in the vicinity of 90 degrees, the contrast decreased as the angle deviated. Moreover, when the angle α is small, both the lighting part and the non-lighting part are bluish, and when the angle α is large, the non-lighting part is purple and the lighting part is yellow, and in any case black and white display is impossible. Similar results are obtained for the angle β and the angle γ, but in the case of the angle γ, as described above, when the image is rotated from 50 degrees to 90 degrees, the black and white display is reversed.

FIG. 10 is a diagram showing another specific example of the twist angle θ and the like. The basic structure is the same as the specific example shown in FIG. However, the twist angle of the liquid crystal molecules of the liquid crystal layer 50 is 260
The difference is that Δn ₁ · d ₁ is about 0.65 μm to 0.75 μm. The Δn ₂ · d ₂ of the parallel alignment liquid crystal layer used as the uniaxial transparent birefringent member 40 is about 0.58 μm, which is the same as the above-mentioned specific example. The thickness d ₁ (μm) of the liquid crystal layer and the helical pitch p of the nematic liquid crystal material to which the optically active substance is added.
The ratio with (μm) was set to d / p = 0.72.

At this time, by setting the angle α to about 100 degrees, the angle β to about 35 degrees, and the angle γ to about 15 degrees, the same black and white display as that of the first specific example could be realized. Also, the reverse black-and-white display is possible by rotating the position of the axis of the lower polarizing plate by 50 to 90 degrees from the above value, which is similar to the first specific example. The tendency with respect to the deviations of the angles α, β, and γ is almost the same as in the first specific example.

In each of the specific examples described above, a parallel alignment liquid crystal cell having no twist of liquid crystal molecules is used as the uniaxial transparent birefringent member 40, but a liquid crystal layer in which liquid crystal molecules are twisted by about 20 to 60 degrees is used. There is less color change depending on the angle. Like the above-mentioned liquid crystal layer 50, this twisted liquid crystal layer is formed by sandwiching liquid crystal between a pair of transparent substrates that have been subjected to the alignment treatment so that the alignment treatment directions intersect a predetermined twist angle. It In this case, the bisected angle of the two orientation treatment directions sandwiching the twisted structure of the liquid crystal molecules may be treated as the optical axis of the birefringent member. A transparent polymer film may be used as the birefringent member 40 (uniaxially stretched film is preferable at this time). In this case, PET (polyethylene terephthalate), acrylic resin film and polycarbonate are effective as the polymer film.

Further, in the above specific example, the single birefringent member was single, but in addition to the birefringent member 40 in FIG. 7, another birefringent member is provided between the lower electrode substrate 12 and the lower polarizing plate 16. It is also possible to insert a bending member. In this case, Δn ₂ · d ₂ of these birefringent members should be readjusted.

However, as shown in FIG. 12, the upper electrode substrate 1
Red, green, and blue color filters 33R, 33G, 3 on top of 1
By providing the light shielding film 33D between the filters 3B and the respective filters, multicolor display is possible. FIG. 9 shows the alignment direction of the liquid crystal molecules, the twisting direction of the liquid crystal molecules,
The relationship between the axis direction of the polarizing plate and the optical axis of the birefringent member is shown.

In FIG. 12, each filter 33
On the R, 33G, 33B and the light shielding film 33D, a smoothing layer 23 made of an insulating material is formed in order to reduce the influence of these irregularities, and then an upper electrode 31 and an alignment film 21 are formed.

As described above, according to the above specific example, it is possible to realize a field effect liquid crystal display element having excellent time-division driving characteristics and capable of monochrome and multicolor display.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and it goes without saying that various modifications can be made without departing from the scope of the invention. . For example, in the above-described embodiment, an example in which the present invention is applied to a simple matrix type liquid crystal display device is shown, but it goes without saying that the present invention is also applicable to an active matrix type liquid crystal display device using a thin film transistor or the like as a switching element. Yes.

[0052]

As described above, according to the present invention,
Since the light guide plate can be held in the case with a simple structure, the process and cost of processing holes and cutouts in the light guide plate are not necessary, so the cost of the light guide plate can be reduced and the reliability can be improved. Therefore, it is possible to provide a liquid crystal display device having high cost and low cost. Further, by reducing the height of the stopper, it is possible to improve the brightness uniformity and brightness of the light guide plate.

[Brief description of drawings]

FIG. 1A is a plan view of a light guide plate of a liquid crystal display device according to a first embodiment of the present invention and a mold case accommodating a fluorescent tube;
(B) is a sectional view taken along the line bb of (a), (c)
Is a sectional view taken along the line cc of (a), and (d) is a perspective view of an essential part (a fluorescent tube is not shown).

FIG. 2A is a plan view of a light guide plate of a liquid crystal display device according to a second embodiment of the present invention and a mold case accommodating a fluorescent tube;
(B) is a sectional view taken along the line bb of (a), (c)
Is a sectional view taken along the line cc of (a), and (d) is a perspective view of an essential part (a fluorescent tube is not shown).

FIG. 3 is an overall perspective view of a liquid crystal display device to which the present invention can be applied.

FIG. 4 is a block diagram of an example of a laptop computer.

FIG. 5 is a perspective view of an example of a laptop computer.

FIG. 6 shows an example of a relationship among an alignment direction of liquid crystal molecules, a twisting direction of liquid crystal molecules, a direction of a polarizing plate axis, and an optical axis of a birefringent member in a simple matrix type liquid crystal display device to which the present invention is applicable. FIG.

FIG. 7 is an exploded perspective view of an essential part of an example of a liquid crystal display element.

FIG. 8 is an explanatory diagram showing a relationship among a twist direction of liquid crystal molecules, a direction of an axis of a polarizing plate, and an optical axis of a birefringent member in a liquid crystal display element of another example.

9 is a graph showing contrast and transmitted light color-crossing angle α characteristics for the example of FIG. 6 of the liquid crystal display device.

FIG. 10 is an explanatory diagram showing a relationship among an alignment direction of liquid crystal molecules, a twisting direction of liquid crystal molecules, a direction of an axis of a polarizing plate, and an optical axis of a birefringent member in a liquid crystal display element of still another example.

FIG. 11 is a diagram for explaining how to measure intersection angles α, β, and γ.

FIG. 12 is a partially cutaway perspective view of an example of an upper electrode substrate portion of a liquid crystal display element.

13 (a) and 13 (b) are plan views of a mold case accommodating a light guide plate and a fluorescent tube of a conventional liquid crystal display device, respectively.

[Explanation of symbols]

1 ... Stopper, 2 ... Light guide plate, 3 ... Fluorescent tube, 4 ... Mold case.

Claims (5)

[Claims] 1. A liquid crystal display device in which a light guide plate arranged below a liquid crystal display element and a fluorescent tube arranged along the side surface near the side surface of the light guide plate are housed in a case, wherein the light guide plate is substantially It has a quadrangular shape, and prevents movement of the light guide plate to the fluorescent tube side by at least one stopper provided in contact with one side of the light guide plate on the fluorescent tube side or in the vicinity of the one side. In addition, the liquid crystal display device is characterized in that the remaining three sides of the light guide plate are held by the inner wall of the case formed along the shape of the light guide plate. 2. The liquid crystal display device according to claim 1, wherein the case is a molded case formed by integral molding. 3. The liquid crystal display device according to claim 1, wherein the stopper is provided integrally with the case. 4. A liquid crystal display device in which a light guide plate arranged under a liquid crystal display element and a fluorescent tube arranged along the side surface near the side surface of the light guide plate are housed in a case integrally formed. The light guide plate has a substantially quadrangular shape, and the light guide plate is provided in contact with or near one side of the light guide plate on the fluorescent tube side by at least one stopper provided integrally with the case. The liquid crystal display device is characterized in that it is prevented from moving toward the fluorescent tube side, and the remaining three sides of the light guide plate are held by the inner wall of the case formed along the shape of the light guide plate. 5. The liquid crystal display device according to claim 1, wherein the height of the stopper is smaller than the thickness of the light guide.