JPH10301106A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain sufficient necessary reflection luminance without using a back light even in the case of performing color display by providing a reflecting means between a second substrate and a belt-like reflection electrode group through transparent resin film. SOLUTION: A belt-like micro-color filter layer 2 and a transparent resin layer 3 are formed on the surface of a first transparent substrate 1a, and a belt-like transparent electrode group 4 is arranged on it. Reflection film 5 is formed on a second transparent substrate 1b by a sputtering method, and silver or aluminum is suitably used as a material. Acrylic resin which is a transparent resin and whose film thickness is about 1 μm is formed on the reflection film 5 as the transparent resin layer 6, and also a reflection electrode group 7 is formed on it. The first transparent substrate 1a and the second transparent substrate 1b constituted thereby are stuck to be opposed to each other so as to make the transparent electrode group 4 and the reflection electrode group 7 orthogonal to each other, and a liquid crystal layer 8 is formed by injecting liquid crystal between them, so that a liquid crystal panel is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reflection type liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, with the remarkable improvement in display performance due to the progress of liquid crystal display technology, the application fields of liquid crystal display devices have expanded from calculators to word processor and personal computer displays.

Recently, portable information terminals (hereinafter referred to as “PDAs”)
Called. There is a need for a liquid crystal display device that can be suitably used as the display of (1). There are various types of liquid crystal display devices such as a transmission type and a reflection type. However, PDAs that are premised on mobile applications require a thin, light and low-power display due to its characteristics. A reflection type liquid crystal display device that does not require a backlight is the one that best meets such a requirement, and the PDA currently being commercialized is
Most of the devices employ a reflection type liquid crystal display device.

FIGS. 3 and 4 are sectional views of a conventional reflection type liquid crystal display device, respectively. The liquid crystal display device shown in FIG. 3 is a reflection type liquid crystal display device using TN liquid crystal, and a band-shaped transparent electrode group 4 is provided on a first transparent substrate 1a.
The second transparent substrate 1b is provided with a strip-shaped transparent electrode group 12 arranged so as to be orthogonal to the transparent electrode group 4.

A liquid crystal display panel having a liquid crystal layer 8 formed by injecting a TN liquid crystal between the pair of transparent substrates 1a and 1b is manufactured, and polarizing plates 10 and 13 are provided on the surface of the panel. It is arranged.

At this time, a reflection plate 15 is provided on the surface of the polarizing plate 13 via a high refractive index layer 14. Usually, the high refractive index layer 14 is formed of acrylic glue, and joins the polarizing plate 10b and the reflecting plate 15 as an adhesive layer.
Its refractive index is about n = 1.5.

In the reflection type liquid crystal display device configured as described above, light incident from the side of the polarizing plate 10 passes through the liquid crystal layer 8 and is reflected by the reflection plate 15 provided outside the liquid crystal panel. The light is emitted again to the polarizing plate 10 side.

The light passing through the liquid crystal layer 8 is
Can be modulated by applying a voltage to. The liquid crystal display device shown in FIG.
This is a reflection type liquid crystal display device using N liquid crystal, and its basic configuration is almost the same as that of the reflection type liquid crystal display device of FIG.

[0009] Such a reflection type liquid crystal display device has the STN
In order to compensate or control coloring peculiar to the liquid crystal mode, a retardation plate 9 is interposed between the polarizing plate 10 and the first transparent substrate 1a.

As described above, the reflection type liquid crystal display device shown in FIGS. 3 and 4 is a thin, light, low power liquid crystal display device which does not require a backlight, and can be suitably used for a PDA or the like. It is.

[0011]

At present, such a reflection type liquid crystal display device is mainly used for a monochrome display. However, a color display can be realized like a conventional transmission type liquid crystal display device. Is required.

In a conventional transmission type liquid crystal display device,
In order to enable color display, a method of forming a micro color filter layer of three colors of red, blue and green on the inner surface of the liquid crystal panel is usually adopted. In this method, light is transmitted through the micro color filter layer. To reduce the transmittance, a high-luminance backlight is used to supplement the transmittance.

However, when the method of forming a micro color filter layer on the inner surface of a liquid crystal panel is applied to a reflection type liquid crystal display device, only the reflection plate 15 provided outside the liquid crystal panel is required to use a backlight. Has a problem that the luminance cannot be increased and the transmittance cannot be compensated.

Further, the incident light that enters from the side of the polarizing plate 10 and passes through the liquid crystal layer 8 must pass through the second transparent substrate 1b before reaching the reflecting plate 15, and the thickness of the transparent substrate 1b There is also a problem that color mixing occurs and the color taste worsens.

To solve such problems, a method utilizing the birefringence of the liquid crystal and a method utilizing the color filter layer by improving the transmittance of the liquid crystal panel have been proposed.

The method of utilizing the birefringence of the liquid crystal is to change the birefringence by controlling the voltage applied to the liquid crystal layer, thereby realizing a color display. It is difficult to increase the number of colors to five or more, because of limitations in controllability and controllability of the liquid crystal layer thickness, and is not suitable for full-scale color display.

A method of using a color filter layer by improving the transmittance of a liquid crystal panel is to use a liquid crystal operation mode without using only one polarizing plate of the liquid crystal display panel or at all. Is to improve the transmittance.

As an example of such a method, a color filter layer is formed on the inner surface of the panel using a guest / host mode as a liquid crystal operation mode, and a voltage from a two-terminal element is applied to the liquid crystal layer via a reflective electrode. And a method of controlling light modulation (Sharp Technical Report, No. 56, 27, (1993)).

As a method of using one polarizing plate,
An example in which white and black light modulation is possible by specifying the retardation of a liquid crystal layer and an optical compensating member and the optical axis of a polarizing plate and an optical compensating member in a reflection type STN liquid crystal (Japanese Patent Laid-Open No. 7-84252). Yes, if this is combined with a color filter layer, color display is possible in principle.

However, in the above-described method of using the color filter layer by improving the transmittance of the liquid crystal panel, although the light reflected by the reflective electrode can be used, the light passes through the gap between the reflective electrodes. There is a problem that light cannot be reflected, and sufficient reflection luminance suitable for color display cannot be obtained.

Further, the problem that light passing through the color filter layer is mixed by the thickness of the second transparent substrate 1b to deteriorate the color has not been solved yet. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a reflection type liquid crystal display device which has a high reflection luminance and can perform good color display without causing color mixture.

[0022]

The present invention is characterized in that a reflection film is provided inside a liquid crystal display panel. According to the present invention, it is possible to provide a reflection type liquid crystal display device having high reflection luminance, good visibility, high image quality, and capable of color display with a relatively simple configuration.

[0023]

According to a first aspect of the present invention, there is provided a reflective liquid crystal display device, wherein a liquid crystal is interposed between a first substrate and a second substrate, and a band-shaped transparent electrode group is disposed on the first substrate. A reflective liquid crystal display device in which a band-shaped reflective electrode group arranged in a direction orthogonal to the band-shaped transparent electrode group is provided on the second substrate, wherein the second substrate and the band-shaped transparent electrode group are arranged. A reflection means is disposed between the reflective electrode group and the reflective electrode group via a transparent and thin resin film.

According to this structure, the light passing through the gap between the reflective electrode groups is reflected by the reflecting means, and the reflective electrode group itself can also reflect the incident light. A necessary and sufficient reflection luminance can be obtained without using it.

Further, since the resin film interposed between the second substrate and the reflection electrode is transparent and thin, the problem of deterioration of visibility due to parallax is solved. Further, since the incident light is reflected without passing through the second transparent substrate, poor color due to color mixing is also eliminated.

According to a second aspect of the present invention, there is provided a reflective liquid crystal display device according to the first aspect, wherein the reflecting film as the reflecting means is arranged below the light transmitting region formed in the gap between the belt-like reflecting electrode groups. It is characterized by having been established.

According to this configuration, incident light that is not reflected by the reflection electrode group can be efficiently reflected. Claim 3
The reflective liquid crystal display device described in claim 1 or 2
Wherein a color filter layer formed so as to have a light transmitting region is provided in a shape and position corresponding to either the band-shaped transparent electrode group or the band-shaped reflective electrode group.

According to this structure, even if a color filter layer is formed on the inner surface of the panel, a reflection type liquid crystal display device having high reflection luminance and capable of color display can be realized. According to a fourth aspect of the present invention, there is provided the reflective liquid crystal display device according to any one of the first to third aspects, wherein at least one of the constituent materials of the reflective electrode group and the reflective surface of the reflective film as the reflective means is any one of silver and aluminum. Or is included.

According to this configuration, it is possible to improve the reflection luminance of the reflection electrode group and the reflection surface of the reflection film as the reflection means. According to a fifth aspect of the present invention, there is provided a reflective liquid crystal display device according to any one of the first to fourth aspects, wherein a white film is provided instead of the reflective film.

According to this configuration, the gap between the electrode groups, that is, the area other than the pixel electrodes is made whiter, and the paper white display performance as the visibility of the liquid crystal display panel can be improved.

According to a sixth aspect of the present invention, in the reflection type liquid crystal display device according to the fifth aspect, the constituent material of the white film is at least one of magnesium oxide, barium sulfate, and zinc oxide.

According to this configuration, a white film suitable for a reflection type liquid crystal display device can be provided. Hereinafter, embodiments of the present invention will be described with reference to FIGS. (Embodiment 1) FIG. 1 is a sectional view of a reflection type liquid crystal display device according to (Embodiment 1) of the present invention.

On the surface of the first transparent substrate 1a, strip-shaped micro color filter layers 2 are arranged at equal intervals.
The micro color filter layer 2 is formed of a dielectric layer formed in a strip shape so as to form one pixel with three colors of red, blue and green, and is colored by a pigment.

On the surface of the micro color filter layer 2,
A transparent resin layer 3 is applied and formed on the micro color filter layer 2 to smooth the unevenness of the film thickness of the micro color filter layer 2, and a band-shaped transparent electrode group 4 is further formed thereon.
Are arranged in a direction orthogonal to.

For the transparent electrode group 4, an oxide of indium and tin used in a normal liquid crystal panel is used. A reflection film 5 is formed on the second transparent substrate 1b by a sputtering method, and silver or aluminum can be suitably used as the material.

An acrylic resin, which is a transparent resin, is formed on the reflection film 5 as a transparent resin layer 6 with a thickness of about 1 μm. Further, a reflective electrode group 7 is formed thereon.
Like the reflection film 5, the reflection electrode group 7 is formed by depositing silver or aluminum by a sputtering method, and is patterned into the shape of a strip-shaped electrode group. Further, the reflective electrode group 7 may be formed by forming a titanium film under the aluminum film formed by the above-described sputtering method. With such a configuration, the moisture resistance reliability is improved.

The first transparent substrate 1 constructed as described above
a and the second transparent substrate 1b are bonded so that the transparent electrode group 4 and the strip-like reflective electrode group 7 are opposed to each other so as to be orthogonal to each other, and a liquid crystal is injected between them to form a liquid crystal layer 8, thereby forming a liquid crystal panel. It is made.

The liquid crystal layer 8 is oriented parallel to the first transparent substrate 1a and the second transparent substrate 1b so as to have no twist. Then, a retardation plate 9 and a polarizing plate 10 are sequentially laminated on the surface of the first transparent substrate 1a of the liquid crystal panel.

The retardation plate 9 is set so that its slow axis is orthogonal to the alignment direction of the liquid crystal layer 8. Further, the retardation plate 9 and the liquid crystal layer 8 are designed to have substantially the same retardation.

With the configuration described above, the polarizing plate 1
The light that has entered from the 0 side passes through the liquid crystal layer 8 from the phase difference plate 9, and the light that has reached the reflective electrode group 7 is reflected in the same linear polarization state as the incident light, and is further reflected by the polarizing plate 10. At the point of arrival, the light enters a so-called normally white mode in which the light is again emitted in the state of incident linear polarization.

The light passing through the transmitting portion formed in the gap between the reflecting electrode group 7 and the reflecting electrode group 7 is reflected by the reflecting film 5 provided below the transmitting portion and returned to the observer side again. Therefore, a clear display can be obtained.

Further, since the transparent resin layer 6 provided on the second transparent substrate 1b is as thin as about 1 μm, deterioration of visibility due to parallax can be eliminated, and the reflection film 5 is provided inside the liquid crystal panel. As a result, the incident light does not pass through the second transparent substrate 1b, so that poor color due to color mixing can be eliminated.

Further, the retardation plate 9 and the liquid crystal layer 8 are designed to have substantially the same retardation, so that optical compensation can be performed. Further, by forming the micro color filter layer 2 in a shape corresponding to the reflection electrode group 7 and forming a gap, a clear color display can be achieved.

In the above (Embodiment 1), the micro color filter layer 2 has a shape corresponding to the reflective electrode group 7, but the micro color filter layer 2 may have a shape corresponding to the transparent electrode group 4. Good.

As described above (Embodiment 1),
Even in a reflection type liquid crystal display device, it is possible to provide a liquid crystal display device having high reflection luminance, good visibility, and suitable for clear color display.

A specific example of the reflection type liquid crystal display device in the above (Embodiment 1) is shown below. (Example 1) In the above (Embodiment 1), the reflection film 5
The reflection electrode group 7 was formed by sputtering aluminum. The reflective electrode group 7 had a thickness of about 2,000 Å and was formed in a pattern of a strip-like electrode group.

The retardation of the liquid crystal layer 8 and the phase difference plate 9 is 385 nm, and the anisotropy Δ
n was set to 0.09, and the thickness d of the liquid crystal layer was set to 4.3 μm. The light incident from the side of the polarizing plate 10 passes through the liquid crystal layer 8 from the phase difference plate 9, and the light that reaches the reflective electrode group 7 is reflected in the same linearly polarized state as the incident light. When the light reaches the side, the light enters a so-called normally white mode in which the light is again emitted in the state of incident linear polarization.

Further, since the light that has passed through the light transmitting region formed in the gap between the reflective electrode groups 7 is returned to the observer side by the reflective film 5, a clear display can be obtained. Specifically, the integrated reflectance of the liquid crystal panel of this (Example 1) was 15%, and the integrated reflectance of the conventional example was 12%.

By applying a voltage to the liquid crystal layer 8 separately from the above structure, light passing through the liquid crystal layer 8 can be modulated, and the effective retardation of the liquid crystal layer 8 decreases with the applied voltage. .

When the difference in retardation between the liquid crystal layer 8 and the retardation plate 9 becomes １ ／ of the light wavelength, the reflection surface becomes a circularly polarized state. The state becomes a linearly polarized state in the orthogonal direction, and at this time, a dark state can be realized.

As described above, by electrically controlling the brightness in correspondence with the RBG of the micro color filter, a reflective liquid crystal display device capable of displaying a clear color was obtained.

(Embodiment 2) FIG. 2 is a sectional view of a reflective liquid crystal display device according to (Embodiment 2) of the present invention. The configuration is almost the same as the above (Embodiment 1), except that a white film 11 is used instead of the reflection film 5 in (Embodiment 1).

As a constituent material of the white film 11, magnesium oxide, barium sulfate, and zinc oxide can be preferably used. Even with such a configuration, the above (Embodiment 1)
Similarly to the above, the light that has passed through the light transmission region in the gap between the reflective electrode groups is diffusely reflected by the white film 11 toward the observer.

As a result, the gap between the electrodes, that is, the area other than the pixel electrodes can be made whiter, and the paper white display performance can be improved as the visibility of the liquid crystal display panel.
It can be improved in terms of whitening of the reflected light.

In each of the above embodiments, an example in which the electric field control birefringence effect is used as the liquid crystal operation mode has been described. However, as described above, the number of polarizing plates used is one by using a reflective electrode. Operation modes that can be displayed below can be similarly implemented.

It is apparent that the contents of the present invention can be applied to any of simple matrix driving and driving by a switching element such as a TFT. Further, in each of the above embodiments, the case where color display is realized using a micro color filter has been described. However, even in the case of black and white display without using a micro color filter, this method is used to increase the reflection luminance. It is an effective means.

[0057]

As described above, according to the present invention, since the reflection means is provided between the second substrate and the belt-like reflection electrode group via a transparent resin film, the reflection means passes through the gap between the reflection electrode groups. The light is reflected by the reflection means, and the reflection electrode group itself can also reflect the incident light, so that a necessary and sufficient reflection luminance can be obtained without using a backlight even when performing color display.

Further, by arranging the reflection means inside the second substrate via the transparent resin film, the deterioration of visibility can be solved. Further, by forming the reflection means inside the liquid crystal display panel, color mixture caused by the thickness of the glass substrate is eliminated, and a reflection type liquid crystal display device with good color display can be obtained.

Therefore, according to this configuration, it is possible to realize a reflective liquid crystal display device capable of displaying a clear color even if a color filter layer is formed on the inner surface of the panel. In this way, the reflection brightness is increased by a relatively simple method of forming the reflection film inside the liquid crystal panel and located in the light transmission area, and the reflection type that does not cause color mixture even when a micro color filter layer is used. A liquid crystal display device is obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a reflective liquid crystal display device in Embodiment Mode 1.

FIG. 2 is a cross-sectional view of a reflective liquid crystal display device in Embodiment Mode 2.

FIG. 3 is a cross-sectional view of a conventional reflective liquid crystal display device.

FIG. 4 is a cross-sectional view of another conventional reflective liquid crystal display device.

[Explanation of symbols]

 Reference Signs List 1a first transparent substrate 1b second transparent substrate 2 micro color filter layer 4 transparent electrode group 5 reflective film 6 transparent resin layer 7 reflective electrode group 8 liquid crystal layer 11 white film

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hisanori Yamaguchi 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A liquid crystal is interposed between a first substrate and a second substrate, a band-shaped transparent electrode group is disposed on the first substrate, and the band-shaped transparent electrode group is disposed on the second substrate. A reflective liquid crystal display device in which a strip-shaped reflective electrode group aligned in a direction orthogonal to a transparent electrode group is disposed, wherein a transparent and thin layer is provided between the second substrate and the strip-shaped reflective electrode group. A reflection type liquid crystal display device in which reflection means is provided via a resin film. 2. The reflection type liquid crystal display device according to claim 1, wherein the reflection film as the reflection means is disposed below the light transmission region formed in the gap between the belt-like reflection electrode groups. 3. A color filter layer formed so as to have a light transmitting region in a shape and a position corresponding to one of the band-shaped transparent electrode group and the band-shaped reflection electrode group. 3. The reflective liquid crystal display device according to 2. 4. A reflective liquid crystal display according to claim 1, wherein at least one of the constituent materials of the reflective electrode group and the reflective surface of the reflective film as the reflective means contains any of silver and aluminum. apparatus. 5. The reflection type liquid crystal display device according to claim 1, further comprising a white film instead of the reflection film. 6. A white film comprising magnesium oxide,
6. The reflection type liquid crystal display device according to claim 5, wherein the reflection type liquid crystal display device is at least one of barium sulfate and zinc oxide.