JPH06347781A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide a liquid crystal display device having a spacer with which the arrangement of a sponge spacer with easy assembly operation and good accuracy is possible. CONSTITUTION:This liquid crystal display device has the frame-shaped spacer 13 consisting of a resin material of an opaque color or dark color, such as black, across the periphery of a photoconductor assembly 37 of a frame-shaped intermediate frame 42 and the inside frame of the intermediate frame. The frame-shaped spacer 13 is formed out of a sheet-like resin material by pressing, etc., and the spacer itself maintains a prescribed shape. Then, the spacer is mounted and placed across the periphery of the photoconductor assembly 37 of the frame-shaped intermediate frame 42 and the inside frame of the intermediate frame without intruding into a display region.

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,
The present invention relates to a field-effect liquid crystal display device having particularly excellent time-division driving characteristics and capable of monochrome and multicolor display.

[0002]

2. Description of the Related Art As one type of liquid crystal display device, a so-called twisted nematic type (TN) is a spiral structure twisted by 90 degrees by a nematic liquid crystal having a positive dielectric anisotropy between two electrode substrates. In addition, a polarizing plate is disposed outside both electrode substrates such that the polarization axis (or absorption axis) thereof is orthogonal or parallel to the liquid crystal molecules adjacent to the electrode substrate (Japanese Patent Publication No. -136
No. 66).

In such a liquid crystal display device having a twist angle (α) of 90 degrees, there are problems in terms of the steepness (γ) of the change in the transmittance of the liquid crystal layer versus the voltage applied to the liquid crystal layer and the viewing angle characteristic. ,
The number of time divisions (corresponding to the number of scanning electrodes) was 64, which was a practical limit. However, in order to cope with the recent demands for improving the image quality and increasing the display information amount for liquid crystal display elements, a super twisted nematic (STN) has been proposed in which the twist angle α of liquid crystal molecules is larger than 180 degrees, and the birefringence of this STN is Applied Physics is to improve the time-division drive characteristics and increase the number of time-division by utilizing the effect.
Letter 45, No.10, 1021 1984 (Applied Physics Lette
r, TJScheffer, J.Nehring: "A new, highly multiplexab
le liquidcrystal display "), and a super twisted birefringence effect (SBE) liquid crystal display device has been proposed.

This type of liquid crystal display device includes a liquid crystal display panel including an upper frame having a display window, a liquid crystal plate in which a drive circuit board is integrated, a light guide assembly including a light diffusion plate and a light guide plate, This light guide assembly is housed and at least one side has an intermediate frame on which a linear Bakulite light source is mounted and a lower frame, and these are laminated in the above order,
The upper frame and the lower frame are connected and fixed.

[0005]

In the conventional liquid crystal display device described above, black sponge spacers are attached to the four corners of the light guide assembly housed in the inner frame of the frame-shaped intermediate frame, and the light from the backlight light source is attached. Since it is configured to prevent the liquid from leaking directly to the liquid crystal display panel side, it is difficult to assemble it and it is difficult to attach the sponge spacers with high precision. However, there is a problem of causing display failure.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a liquid crystal display device provided with a spacer which is easy to assemble and is capable of accurately arranging sponge spacers.

[0007]

In order to achieve the above object, the present invention, as shown in FIG. 1, includes an upper frame 1 having a display window 3 and a liquid crystal plate in which a drive circuit board 35 is integrated. A liquid crystal display panel 62, a light guide assembly 37 composed of a light diffusion plate and a light guide plate, a back light source 36 having a linear shape on at least one side, the light guide assembly being housed in an inner frame.
In a liquid crystal display device in which a frame-shaped intermediate frame 42 and a lower frame 2 are stacked in this order, and the upper frame 1 and the lower frame 2 are connected and fixed, the frame-shaped intermediate frame 42 A frame-shaped spacer 13 made of a resin material having a dark color such as opaque or black is provided across the periphery of the light guide assembly 37 and the inner frame of the intermediate frame.

Further, according to the present invention, as shown in FIG. 2, a pin 27 is provided at a corner portion of an inner frame for accommodating the light guide assembly 37 of the intermediate frame 42, and a corner of the frame-shaped spacer 13 is provided. A hole 26 is formed through the pin 27, and the hole 26 is inserted through the pin 27 to define the mutual position of the frame spacer 13 and the intermediate frame 42.

The pins 27 and holes 26 may be provided at two corners or three corners instead of being provided at all four corners of the intermediate frame and the spacer as shown.

[0010]

The frame-shaped spacer 13 made of an opaque resin material is made of a sheet-shaped resin material by pressing or the like,
It retains its own shape. Therefore, the frame-shaped intermediate frame 42 is placed across the periphery of the light guide assembly 37 and the inner frame of the intermediate frame without penetrating the display area.

Further, the pins 27 provided at the corners of the inner frame of the intermediate frame 42 for accommodating the light guide assembly 37.
And the holes 26 provided at the corners of the frame-shaped spacer 13 and the frame-shaped spacer 13 and the intermediate frame 42.
The mutual position with and can be precisely specified.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a developed perspective view for explaining the configuration of a liquid crystal display device according to the present invention, in which 1 is an upper frame,
3 is a liquid crystal display window, 62 is a liquid crystal display panel, 35 is a drive circuit board, 13 is a spacer, 37 is a light guide assembly composed of a light diffusing plate and a light guide plate, and 42 is a frame shape for mounting a linear bakulite light source. An intermediate frame, 36 is a backlight light source (lamp) composed of a cold cathode tube, 17 is a lamp cover, and 2 is a lower frame.

Reference numeral 18 is a cut-and-raised piece which is brought into contact with the ground pad 24 formed on the drive circuit board 35, and 20.
Is a claw fixed to a claw receiver 25 formed on the lower frame 2, 1
4 is an adhesive tape for fixing the upper frame 1 and the liquid crystal display panel 62, 55 and 56 are cutouts provided at positions symmetrical to a line orthogonal to the center of the backlight, and 57 and 58 are longitudinal directions of the backlight light source 36. Cutouts provided in 5
Reference numerals 3 and 54 are notches provided at lower portions of both ends of the backlight light source 36.

In FIG. 1, the liquid crystal display device is sandwiched and fixed by an upper frame 1 and a lower frame 2 in the order shown. A linear light source (backlight light source) 36 including a cold cathode tube is installed at one end of the intermediate frame 42, and the lamp cover 1
At 7, the direct light in the direction of the liquid crystal display panel 62 is blocked, and the emitted light is directed to the light guide assembly 37 side including the light diffusion plate and the light guide plate.

The spacer 13 is made of a dark (preferably black) resin, and is interposed between the liquid crystal display panel 62 and the light guide assembly 37 housed in the inner frame formed in the intermediate frame 42 to form a display area. Determine. FIG. 2 is a developed perspective view for explaining the configuration of a frame-shaped spacer and a frame-shaped intermediate frame that constitute an embodiment of the liquid crystal display device according to the present invention, and the same symbols as those in FIG. 1 correspond to the same portions.

As shown in the figure, pins 27 are formed at the four corners of the inner frame of the frame-shaped intermediate frame 42, and at the four corners of the frame-shaped spacer 13 of the frame-shaped intermediate frame 42. Holes 26 are formed through the pins 27 formed at the four corners of the inner frame. In this configuration, by inserting the pins 27 at the four corners of the inner frame of the frame-shaped intermediate frame 42 through the four corners 26 of the frame-shaped spacer 13, the light guide assembly 37 and the inner frame of the frame-shaped intermediate frame 42 are inserted. The predetermined portion that straddles is shielded from light, and the adhesiveness with the liquid crystal display panel 62 placed and laminated thereon is guaranteed.

A specific example in which the above structure is applied to a super twisted nematic (STN) type liquid crystal display device will be described below. In the following drawings, components having the same function are designated by the same reference numeral, and repeated description thereof will be omitted. “Specific Example 1” FIG. 3 shows an arrangement direction of liquid crystal molecules (for example, a rubbing direction), a twisting direction of liquid crystal molecules, a polarization axis (or an absorption axis) direction of a polarizing plate when the liquid crystal display device 62 according to the present invention is viewed from above. And the optical axis direction of the member that brings about the birefringence effect. FIG. 4 shows the liquid crystal display device 6 according to the present invention.
The principal part 2 perspective view is shown.

The twist direction 10 of the liquid crystal molecules and the twist angle θ
Is the rubbing direction 6 of the alignment film 21 on the upper electrode substrate 11, the rubbing direction 7 of the alignment film 22 on the lower electrode substrate 12, and the nematic liquid crystal layer 50 sandwiched between the upper electrode substrate 11 and the lower electrode substrate 12. It is defined by the type and amount of the optically active substance added. In FIG. 4, 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 form a twisted spiral structure, A so-called 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 in contact with the liquid crystal with a cloth, for example, in one direction, is adopted. The rubbing direction at this time, that is, the rubbing direction, the rubbing direction on the upper electrode substrate 11 and the rubbing direction 7 on the lower electrode substrate 12 are the alignment directions of the liquid crystal molecules.

On the two sheets thus oriented,
The lower electrode substrates 11 and 12 are respectively rubbed in directions 6 and 7
Are opposed to each other with a gap d ₁ so that they cross each other at about 180 to 360 degrees.
Is bonded by a frame-shaped sealing material 52 having a notch 51 for injecting liquid crystal, and a nematic liquid crystal having a positive dielectric anisotropy and a predetermined amount of an optical rotatory substance added is sealed in the gap, whereby liquid crystal molecules are Is the twist angle θ between the electrode substrates in the figure.
The molecular arrangement has a helical structure. In addition, 31 and 32 are upper and lower electrodes, respectively.

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 thus constructed, and the member 40 and the liquid crystal are also provided. Upper and lower polarizing plates 15 and 16 are provided with the cell 60 interposed therebetween. The twist angle θ of the liquid crystal molecules in the liquid crystal 50 is preferably 200 degrees to 300 degrees, but excellent time division characteristics are avoided by avoiding the phenomenon that the lighting state near the threshold value of the transmittance-applied voltage curve is an orientation that scatters light. From the practical viewpoint of maintaining the above condition, the range of 230 degrees to 270 degrees is more preferable.

This condition basically makes the response of the liquid crystal molecules to the voltage more sensitive and acts so as to realize an excellent time division characteristic. In order to obtain excellent display quality, the product [Delta] n ₁ · d ₁ of the refractive index anisotropy [Delta] n ₁ and a thickness d ₁ of the liquid crystal layer 50 is preferably from the 0.5 [mu] m 1.0 micron
m, more preferably 0.6 μm to 0.9 μm.

The birefringent member 40 acts so as to modulate the polarization state of light passing through the liquid crystal cell 60, and converts what could be colored display by the liquid crystal cell 60 alone into black and white display. For this purpose, the product [Delta] n ₂ · d ₂ of the refractive index anisotropy [Delta] n ₂ and the thickness d ₂ of the birefringent member 40 is extremely important, 0.8 micron preferably from 0.4μm
m, more preferably 0.5 μm to 0.7 μm.

Further, since the liquid crystal display device 62 according to the present invention uses the elliptically polarized light due to the birefringence, the polarizing plate 15,
When the uniaxial transparent birefringent plate is used as the birefringent member 40, the relationship between the 16 axes and the liquid crystal alignment directions 6 and 7 of the electrode substrates 11 and 12 of the liquid crystal cell 60 is extremely important. . Here, the effect of the above relationship will be described with reference to FIG. The figure shows the relationship between the axis of the polarizing plate, the optical axis of the uniaxial transparent birefringent member, and the liquid crystal alignment direction of the electrode substrate of the liquid crystal cell when the liquid crystal display device having the configuration of FIG. 4 is viewed from above. is there.

In FIG. 3, 5 is the optical axis of the uniaxial transparent birefringent member 40, 6 is the liquid crystal alignment direction of the birefringent member 40 and the upper electrode substrate 11 adjacent thereto, and 7 is the liquid crystal alignment of the lower electrode substrate 12. Direction 8 is the absorption axis or polarization axis of the upper polarizing plate 15, the angle α is the angle between the liquid crystal alignment direction 6 of the upper electrode substrate 11 and the optical axis 5 of the uniaxial birefringent member 40, and the angle β is the upper direction. The angle γ between the absorption axis or polarization axis 8 of the polarizing plate 15 and the optical axis 5 of the uniaxial transparent birefringent member 40 is the absorption axis or polarization axis 9 of the lower polarizing plate 16 and the lower electrode substrate 1.
2 is the angle formed by the liquid crystal alignment direction 7.

Here, a method of measuring the angles α, β and γ will be defined. In FIG. 8, 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 11 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. 8, but the smaller angle of φ ₁ and φ ₂ is adopted here. That is, since φ ₁ <φ ₂ in FIG.
₁ is the angle of intersection between the optical axis 5 and the liquid crystal alignment direction 6, and since φ ₁ > φ ₂ in FIG. 8B, φ ₂ is the angle of intersection between the optical axis 5 and the liquid crystal alignment direction 6. Of course, either _one may be adopted when φ ₁ = φ ₂ .

In this type of liquid crystal display device, the angles α, β and γ are extremely important. The angle α is preferably 5
0 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 0 to 70 degrees.
It is desirable to set the angle to 0 degree, more preferably to 0 degree to 50 degree.

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 α is set regardless of whether the twist direction 10 is clockwise or counterclockwise. , Β, γ may be within the above range. In FIG. 4, the birefringent member 40 is arranged between the upper polarizing plate 15 and the upper electrode substrate 11, but instead, it is arranged between the lower electrode substrate 12 and the lower polarizing plate 16. Good. In this case, the entire configuration of FIG. 4 is inverted. "Specific example 2" The basic structure is the same as that shown in FIGS. In FIG. 5, the twist angle θ of the liquid crystal molecule is 2
A liquid crystal cell having a parallel orientation (homogeneous orientation), that is, a twist angle of 0 degree was used as the uniaxial transparent birefringent member 40.

Here, the ratio d / p of the thickness d (μm) of the liquid crystal layer and the helical pitch p (μm) of the liquid crystal material added with the optical rotatory substance was set to about 0.53. The alignment films 21 and 22 were formed of a polyimide resin film and used after being 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 about 4 degrees. Δn ₂ · d ₂ of the uniaxial transparent birefringent member 40 is about 0.6 μm.
On the other hand, Δn ₁ · d ₁ of the liquid crystal layer 50 in which the liquid crystal molecules are twisted by 240 degrees 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. It was possible to realize light non-transmission, that is, black display when the voltage was below the threshold, and light transmission, that is, white and black display when the voltage was above a certain threshold. Further, when the axis of the lower polarizing plate 16 is rotated from the above position by 50 to 90 degrees, when the voltage applied to the liquid crystal layer 50 is below the threshold value, it is white, and when the voltage is above the threshold value, it is black. Black and white display was realized.

FIG. 6 shows changes 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 becomes small, both the lit part and the non-lit part become bluish, and when the angle α becomes large, the non-lit part becomes purple and the lit part becomes 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, when the image is rotated from 50 degrees to 90 degrees, the opposite black and white display is performed. The basic structure of "Specific Example 3" is the same as that of "Specific Example 2". 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. 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 in “Specific Example 2”.

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 black and white display similar to the "concrete example 1" can be realized. Also, the reverse black-and-white display is possible by rotating the position of the axis of the lower polarizing plate from the above value by 50 to 90 degrees, which is also the same as "Specific example 2". The inclinations of the angles α, β, and γ with respect to the shift are almost the same as in “Specific Example 2”.

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. When used, the color changes less depending on the angle. This twisted liquid crystal layer is the liquid crystal layer 5 described above.
Like 0, it is formed by sandwiching a 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. In this case, the bisected angle of the two alignment 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, as the polymer film, PET
(Polyethylene terephthalate), acrylic resin, and polycarbonate are effective. Further, in the above specific example, the single birefringent member was used, but in FIG.
In addition to the birefringent member 40, the lower electrode substrate 12 and the lower polarizing plate 1
It is also possible to insert another birefringent member between 6 and 6. In this case, Δn ₂ · d ₂ of these birefringent members may be readjusted. "Specific example 4" The basic structure is the same as that of "specific example 2." However, as shown in FIG. 9, red, green,
Multicolor display is possible by providing the light shielding film 33D between the blue color filters 33R, 22G, 33B and the filters. FIG. 7 shows the relationship among the alignment direction of liquid crystal molecules, the twisting direction of liquid crystal molecules, the direction of the axis of the polarizing plate, and the optical axis of the birefringent member in “Specific Example 4”.

In FIG. 9, a smoothing layer 23 made of an insulating material is formed on each of the color filters 33R, 22G, 33B and the light shielding film 33D to reduce the influence of these irregularities. The upper electrode 31 and the alignment film 21 are formed. FIG. 10 shows a block diagram in which the liquid crystal display module 63 according to the present invention shown in FIG. 1 is used for a display portion of a laptop personal computer, and FIG. 11 shows a state in which the laptop personal computer 64 is mounted.

In FIG. 10, the microprocessor 49
The liquid crystal display module is driven by the drive IC 34 via the control LSI 48 based on the result calculated in (4). According to the present embodiment configured as described above, the frame-shaped spacer made of dark resin prevents the light from the backlight source from directly leaking in the direction of the liquid crystal display panel, and the spacer is precisely incorporated. The work is easy, and the problems of the prior art such as the spacer protruding into the display area can be solved.

The invention described in the claims of the present invention is not limited to the above-mentioned STN type liquid crystal display device, but can be similarly applied to other type liquid crystal display devices equipped with a backlight. Is.

[0037]

As described above, according to the present invention,
By inserting the four corners of the frame-shaped spacer into the pins at the four corners of the inner frame of the frame-shaped intermediate frame constituting the liquid crystal display device, the light guide assembly and the inner frame of the frame-shaped intermediate frame were straddled. It is possible to provide a liquid crystal display device that shields a predetermined portion from light and ensures the adhesiveness with a liquid crystal display panel placed and laminated on the predetermined portion and has no display defect.

[Brief description of drawings]

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

FIG. 2 is an exploded perspective view illustrating the configurations of a frame-shaped spacer and a frame-shaped intermediate frame that constitute an embodiment of the liquid crystal display device according to the present invention.

FIG. 3 is an explanatory diagram of 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 Example 1 of the liquid crystal display device according to the present invention.

FIG. 4 is a perspective view of a main part for explaining a stacking relationship of constituent materials of the liquid crystal display device according to the present invention.

FIG. 5 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 Example 2 of the liquid crystal display device according to the present invention.

FIG. 6 is an explanatory diagram of contrast and transmitted light color-crossing angle α characteristics in Example 1 of the liquid crystal display device according to the present invention.

FIG. 7 is an explanatory diagram of 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 Example 3 of the liquid crystal display device according to the present invention.

FIG. 8 shows an intersection angle α, in the liquid crystal display device according to the present invention.
It is an explanatory view of how to measure β and γ.

FIG. 9 is a partially cutaway perspective view illustrating a configuration of an upper electrode substrate portion in the liquid crystal display device according to the present invention.

FIG. 10 is a block diagram when the liquid crystal display device according to the present invention is used for a display unit of a laptop personal computer.

FIG. 11 is an external view of a liquid crystal display device according to the present invention used in a display unit of a laptop personal computer.

[Explanation of symbols]

1 Upper frame 2 Lower frame 3 Liquid crystal display window 13 Spacer 14 Adhesive tape that fixes the upper frame and liquid crystal display panel 17 Lamp cover 18 Cut and raised piece to be soldered to the ground pad formed on the drive circuit board 20 Formed on the lower frame Claws fixed to the claw holder 26 holes 27 pins 35 drive circuit board 36 backlight light source (lamp) composed of cold cathode tubes 37 light guide assembly composed of a light diffusion plate and a light guide plate 42 an intermediate frame on which linear bakulite is mounted 53, 54 Notches provided in the lower part of both ends of the backlight. 55,56 Cutouts provided at positions symmetrical to a line orthogonal to the center of the backlight 57,58 Cutouts provided in the longitudinal direction of the backlight 62 Liquid crystal display panel.

Claims (2)

[Claims] 1. A liquid crystal display panel comprising an upper frame having a display window, a liquid crystal plate integrated with a drive circuit board, a light guide assembly comprising a light diffusing plate and a light guide plate, and the light guide assembly. A liquid crystal display that is housed in an inner frame and has a frame-shaped intermediate frame on which a linear backlight light source is mounted on at least one side and a lower frame, which are stacked in this order, and the upper frame and the lower frame are connected and fixed. A liquid crystal display device, comprising: a frame-shaped spacer made of an opaque resin material, which straddles a periphery of the light guide assembly of the frame-shaped intermediate frame and an inner frame of the intermediate frame. . 2. The pin according to claim 1, further comprising a pin at a corner portion of an inner frame for accommodating the light guide assembly of the intermediate frame, and a hole for inserting the pin at a corner portion of the frame-shaped spacer. A liquid crystal display device, wherein the hole is inserted into the pin to define a mutual position of the frame-shaped spacer and the intermediate frame.