JPH10171379A - Reflection type guest-host liquid crystal display device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the contrast and lightness of a display of the reflection type guest-host liquid crystal display device which has a light reflecting layer and a 1/4-wavelength plate layer inside. SOLUTION: In the gap between an incidence-side 1st substrate 2 and an opposite- side 2nd substrate 3, guest-host liquid crystal 4 is arranged on the side of the 1st substrate 2 and the 1/4-wavelength plate layer 7 is arranged on the side of the 2nd substrate 3. Further, electrodes 8 and 16 are formed on the sides of the 1st substrate 2 and 2nd substrate 3 to apply a voltage to the guest-host liquid crystal 4. On the side of the 2nd substrate 3, light reflecting layer 9 is provided and reflects incident light 1 by a nearly mirror surface to convert it into reflected light 11. On the side of the 1st substrate 2, a light diffusion layer 10 is arranged and scatters or diffuses the reflected light 11 from behind to the front to convert it into projection light 12. A flattening film 20 is formed filling unevenness of the surface of the light diffusion layer 10 and the surface is smoothed and polished. AN electrode 8 is formed on the surface of the smoothed and polished flattening film 10. Or the electrode 8 may be provided by roughening the surface of the flattening film 20 into a rough surface according to circumstances.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reflection type guest-host liquid crystal display device. More specifically, the present invention relates to a structure in which a quarter-wave plate layer and a light reflection layer are incorporated in a panel to improve the use efficiency of incident light. More specifically, the present invention relates to a technique for efficiently diffusing and emitting reflected light to increase display brightness.

[0002]

2. Description of the Related Art A liquid crystal display device has various modes.
At present, a TN mode or an STN mode using a nematic liquid crystal which is twist-oriented or super-twist-oriented is mainly used. However, these modes require a pair of polarizers due to the principle of operation, and because of their light absorption, low transmittance and a bright display screen cannot be obtained. Cannot be realized. In addition to these modes, a guest-host mode using a dichroic dye has also been developed. The guest-host mode liquid crystal display device performs display using the anisotropy of light absorption of a dichroic dye added to liquid crystal. When a dichroic dye having a rod-like structure is used, the dye molecules have a property of being arranged in parallel with the liquid crystal molecules. Therefore, when an electric field is applied to change the molecular orientation of the liquid crystal, the orientation direction of the dye also changes. Since this dye is colored or not depending on the direction, it is possible to switch between coloration and colorlessness of the liquid crystal display device by applying a voltage.

FIG. 6 shows Heilmeyer.
(A) shows the state of no voltage application, and (B) shows the state of voltage application. The liquid crystal display device is p-type dye and dielectric anisotropy are using positive nematic liquid crystal (N _p LCD). The p-type dichroic dye has an absorption axis substantially parallel to the molecular axis, strongly absorbs the polarized component Lx parallel to the molecular axis, and hardly absorbs the polarized component Ly perpendicular to the molecular axis.
In the state where no voltage is applied as shown in (A), the polarization component Lx contained in the incident light is strongly absorbed by the p-type dye, and the liquid crystal display is colored. In contrast, in the voltage application state (B), the dielectric anisotropy rises in response positive N _p liquid crystal in an electric field, p-type dye is also vertically aligned accordingly. Therefore, the liquid crystal display device is almost colorless, because the polarized light component Lx is only slightly absorbed. The other polarization component Ly contained in the incident light is hardly absorbed by the dichroic dye in both the voltage applied state and the voltage non-applied state. Therefore, in the Heilmeier type guest-host liquid crystal display device, one polarizing plate is interposed in advance, and the other polarization component Ly is removed to improve the contrast.

In a guest-host liquid crystal display device using a nematic liquid crystal, a dichroic dye added as a guest to the liquid crystal of the host is oriented similarly to the nematic liquid crystal. Although the polarized light component parallel to the liquid crystal alignment direction is absorbed, the polarized light component orthogonal to the direction is hardly absorbed. Therefore, in order to obtain a sufficient contrast, one polarizing plate is arranged on the incident side of the liquid crystal display device, and the polarization direction of the incident light is made to coincide with the orientation direction of the liquid crystal. However, in this case, 50% of the incident light is lost in principle by the polarizing plate.
The display becomes dark as in the TN mode. As a method of solving this problem, simply removing the polarizing plate is not appropriate because the on / off value of the absorbance is remarkably reduced, and various measures have been proposed. For example, as shown in FIG. 7, a reflection-type guest-host liquid crystal display device has been proposed in which a polarizing plate is removed from the incident side and a quarter-wave plate and a reflecting plate are attached to the emission side. In this scheme,
The two orthogonal polarization components Lx and Ly are rotated by 90 degrees in the forward and backward directions by the quarter-wave plate, and the polarization components are switched. Therefore, in the off state (absorption state) shown in (A), each of the polarization components Lx and Ly is absorbed in either the incident optical path or the reflected optical path. Further, in the ON state (transmission state) shown in (B), almost none of the polarization components Lx and Ly is absorbed. This can significantly improve the efficiency of use of incident light,
The display device becomes brighter.

[0005]

However, in this structure, since the quarter-wave plate and the reflection plate are externally provided, the liquid crystal display device itself needs to be of a transmission type. In particular, when an active matrix type structure is adopted to enable high-definition and moving image display, a thin film transistor for driving a pixel electrode is integrally formed on a substrate. A considerable part is cut off. Therefore, even if the polarizing plate is removed, the screen of the display device cannot be remarkably brightened. In view of this point, a structure in which a quarter-wave plate and a reflector are built in a display device has been proposed.
For example, it is disclosed in JP-A-6-222351. This is shown in FIG. In the present invention, a structure incorporating a quarter-wave plate and a reflector is referred to as an “integrated polarization conversion guest-host liquid crystal display device”. As shown, this integrated polarization conversion guest-host liquid crystal display device has an
00 side of the first substrate 101 and the first substrate 101
From the second substrate 102 disposed rearward with a predetermined gap
It is composed of The guest host liquid crystal 103 located on the first substrate 101 side and the second substrate 102
And a quarter-wave plate layer 104 located on the side. Further, first and second electrodes 105 and 106 are formed on both the first substrate 101 and the second substrate 102, respectively, and a voltage is applied to the guest-host liquid crystal 103.
Further, a light reflection layer 107 is provided integrally with the electrode 106 on the second substrate 102 side. The light reflecting layer 107 is interposed between the second substrate 102 and the quarter-wave plate layer 104 and substantially reflects the incident light 101 to specular reflection, and emits reflected light 108. Note that a protective layer 109 is interposed between the liquid crystal 103 and the quarter-wave plate layer 104.

In a reflection type guest-host liquid crystal display device, in order to obtain a bright display, it is common to use a reflection electrode such as an aluminum metal film in which the light reflection layer 107 and the electrode 106 are integrated and the aperture ratio is maximized. However, a flat metal film electrode causes specular reflection, so that the viewing angle is extremely limited, and the display becomes metallic rather than paper white. In order to prevent this, it has been proposed that the surface of the light reflection layer of the metal film be finely undulated and have a wide distribution of reflection angles. However, a problem with this method is that a fine undulation process is required. Further, in the integrated polarization conversion guest-host liquid crystal display device, it is necessary to control the quarter-wave plate layer 104 to have a uniform film thickness accurately following the undulation. However, this is very difficult in practice. Further, it is necessary to control the inclination angle distribution of the undulations to set an optimum viewing angle range, but this is also extremely difficult in practice. As described above, forming fine undulations on the surface of the light reflection layer made of a metal film has many difficulties in device manufacturing.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, an object of the present invention is to provide an integrated polarization conversion guest-host liquid crystal display device having a bright and wide viewing angle. The following measures have been taken to achieve this objective. That is, according to the first aspect of the present invention, the reflective guest-host liquid crystal display device has, as a basic configuration, a transparent first substrate on which light is incident from the front, and a predetermined gap from the first substrate. A second substrate disposed rearward. In this gap, a guest-host liquid crystal located on the first substrate side and a quarter-wave plate layer located on the second substrate side are provided.
Furthermore, first and second electrodes are formed on the first substrate side and the second substrate side, respectively, and a voltage is applied to the guest-host liquid crystal. In addition, a light reflection layer is provided integrally with or separately from the second electrode on the second substrate side. The light reflecting layer substantially specularly reflects the light incident thereon between the second substrate and the quarter-wave plate layer. Further, a light diffusion layer is disposed between the first substrate and the first electrode, and scatters and emits light reflected from behind toward the front. As a characteristic feature, the light diffusion layer is made of a film in which a resin in which fine particles are dispersed is applied to the first substrate at a constant thickness, and further coated so as to fill irregularities on the surface of the light diffusion layer and is polished smoothly. And a flattening film. The first electrode is formed on the surface of the flattened film polished smooth. The reflective guest-host liquid crystal display device having such a configuration is manufactured by the following steps. First, a resin in which fine particles are dispersed is applied to the first substrate at a predetermined thickness to form the light diffusion layer. Next, a flattening film is applied so as to fill irregularities on the surface of the light diffusion layer, and the surface is polished smoothly. Subsequently, the first electrode is formed on the surface of the flattened film that has been smooth-polished.

According to the second aspect of the present invention, the reflection type guest-host liquid crystal display device basically has a transparent first substrate on which light is incident from the front and a predetermined gap from the first substrate. And a second substrate disposed rearward. In this gap, a guest-host liquid crystal located on the first substrate side and a quarter-wave plate layer located on the second substrate side are provided. Furthermore, first and second electrodes are formed on the first substrate side and the second substrate side, respectively, and a voltage is applied to the guest-host liquid crystal. In addition, a light reflection layer is provided integrally with or separately from the second electrode on the second substrate side. The light reflecting layer substantially specularly reflects the light incident thereon between the second substrate and the quarter-wave plate layer. In addition, a light diffusion layer is provided between the first substrate and the first electrode, and scatters and emits light reflected from behind toward the front. As a characteristic feature, the light diffusion layer is made of a film in which a resin in which fine particles are dispersed is coated on the first substrate, and further has a roughened surface coated and roughened on the light diffusion layer. With membrane. The first electrode is formed along a rough surface of the flattening film. Preferably, an alignment film for aligning the guest-host liquid crystal is interposed at an interface between the first electrode and the guest-host liquid crystal. The alignment film has a thickness sufficient to cover and smooth the first electrode formed on the rough surface of the planarization film. Also preferably, the flattening film has a surface roughness of 1 μm to 2 μm. The reflective guest-host liquid crystal display device having such a configuration is manufactured by the following steps. First, a resin in which fine particles are dispersed is applied to the first substrate to form the light diffusion layer. continue,
A flattening film is applied on the surface of the light diffusion layer, and the surface is roughened and ground to be processed into a rough surface. Subsequently, the first electrode is formed along the rough surface of the planarization film.

According to the present invention, the light diffusion layer is provided on the first substrate on the incident side and the emission side, and the mirror-reflecting layer is provided on the second substrate on the reflection side. The light reflected from the rear second substrate side is diffused and emitted by the front light diffusion layer.
For this reason, the angle distribution of the emitted light can be widened, the viewing angle can be improved, and a display having a paper-white appearance instead of metallic can be obtained. In particular, according to the first aspect of the present invention, the light diffusion layer is formed by mixing fine particles having different refractive indices in a resin (polymer matrix), and then coating the fine particles on the first substrate to form a film. I have. Further, a flattening film is coated so as to fill the unevenness of the light diffusion layer, and the flattening film is mechanically polished to smooth the surface. With such a structure,
It is possible to stably manufacture a light diffusion layer having a constant diffusion property and flatness. According to the second aspect of the present invention, the flattening film applied on the light diffusion layer has a roughened surface. The electrodes are formed along the rough surface of the flattening film. That is, the boundary between the light diffusion layer and the electrode has a fine rough surface structure. As a result, unnecessary reflected light due to a mismatch in refractive index between the electrode and the flattening film located below the light diffusion layer is reduced.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic partial sectional view showing a first embodiment of a reflective guest-host liquid crystal display device according to the present invention. This device is a so-called integrated polarization conversion guest-host liquid crystal display device, and incorporates a light reflection layer and a quarter-wave plate layer. The present apparatus includes a transparent first substrate 2 on which incident light 1 is incident from the front, and a second substrate 3 disposed rearward from the first substrate 2 via a predetermined gap. In this gap, the guest host liquid crystal 4 is provided with the first substrate 2.
Located on the side. The guest host liquid crystal 4 is composed of, for example, a mixture of a nematic liquid crystal 5 and a dichroic dye 6.
In the same gap, a quarter-wave plate layer 7 is arranged on the second substrate 3 side. Further, first and second electrodes 8 and 16 are formed on both the first substrate 2 side and the second substrate 3 side, respectively, and a voltage is applied to the guest-host liquid crystal 4. Further, a light reflecting layer 9 is provided separately from the electrode 16 on the second substrate 3 side, and the incident light 1 is interposed between the second substrate 3 and the quarter-wave plate layer 7 so as to be substantially specular. reflect. By using the light reflection layer 9 as an electrode, the second electrode 16 can be omitted. In other words, the electrode 16 on the second substrate 3 side and the light reflection layer 9 can be provided integrally. In this embodiment, the electrode 16 is formed on the quarter-wave plate layer 7 having a flat surface. An orientation film 13 is interposed between the guest-host liquid crystal 4 and the electrode 16. The alignment film 13 has been subjected to a rubbing treatment, and aligns the guest-host liquid crystal 4 horizontally, for example. Also, the substrate 2 on the incident side
The surface of the first electrode 8 formed on the inner surface of the
It is covered with.

A light diffusion layer 10 is provided between the first substrate 2 and the first electrode 8, and scatters and outputs reflected light 11 from behind toward the front. This light diffusion layer 10 is composed of fine particles 10b.
Is formed on the first substrate 2 by applying a resin 10a having a predetermined thickness to the first substrate 2. A flattening film 20 is applied so as to fill irregularities on the surface of the light diffusion layer 10. The surface of the flattening film 20 is smooth-polished. The above-mentioned first electrode 8 is formed on the surface of the flattened film 20 that has been smooth-polished. In the integrated polarization conversion guest-host liquid crystal display device having such a configuration, the light reflection layer 9 having a mirror surface is formed on the rear second substrate 3 side, while the light diffusion layer is formed on the inner surface of the front first substrate 2. 10 are formed. The reflected light 11 is diffused by the light diffusion layer 10 and emitted light 12 is emitted forward. The outgoing light 12 has a relatively wide angular distribution due to the diffusing or scattering action of the light diffusing layer 10, so that the viewing angle is improved. Further, since the reflected light 11 is converted into the scattered emission light 12 via the light diffusion layer 10, the display has a metallic white appearance and a paper white appearance.

Here, a method of manufacturing the present display device will be described in detail with reference to FIG. First, the second substrate 3 made of glass or the like is washed, and then a metal film such as aluminum is applied to the surface thereof by sputtering or vacuum evaporation, for example, to a thickness of 40 mm.
The light reflecting layer 9 is formed with a thickness of nm. The light reflecting layer 9 thus obtained is covered with a base layer 15. For example, a solution in which a polyimide resin is dissolved is applied by spin coating and dried to form the underlayer 15. The surface of the underlayer 15 is rubbed with a cloth. Further, a polymer liquid crystal material is applied on the underlayer 15. The polymer liquid crystal is, for example, a side-chain polymer liquid crystal using a benzoate ester mesogen as a pendant. The polymer liquid crystal is dissolved in a solution in which cyclohexanone and methyl ethyl ketone are mixed at a ratio of 8: 2 by 3 to 5% by weight. This solution is for example 10
Spin coating is performed at a rotation speed of 00 rpm to form a polymer liquid crystal film on the second substrate 3. After this, the substrate is heated,
Once the polymer liquid crystal is heated to an optically isotropic state. Subsequently, the heating temperature is gradually lowered to return to a room temperature state through a nematic phase. In the nematic phase, the polymer liquid crystals are arranged along the rubbing direction of the underlayer 15, and a desired uniaxial orientation can be obtained. This uniaxial orientation is fixed by returning the second substrate 3 to room temperature. By such an annealing treatment, liquid crystal molecules contained in the polymer liquid crystal material are uniaxially oriented,
The desired quarter-wave plate layer 7 is obtained. Further, a transparent conductive film such as ITO is formed on the quarter-wave plate layer 7 by sputtering or the like, and an electrode 16 is provided. Further, an orientation film 13 is provided by spin-coating polyimide or the like so as to cover the electrode 16. By subjecting the orientation film 13 to rubbing along a predetermined direction, horizontal orientation of the guest-host liquid crystal 4 in contact therewith can be realized.
The rubbing direction of the alignment film 13 and the rubbing direction of the underlayer 15 intersect at an angle of 45 degrees.

On the other hand, for the substrate 2 on the incident side,
First, a light diffusion layer 10 is formed by applying a resin 10a in which fine particles 10b are dispersed to a predetermined thickness. Specifically, after dispersing fine particles having a refractive index different from that of the resin (for example, silica fine particles or polymer fine particles) in a gel-like polymer adhesive liquid or a polymer solution in which a resin is dispersed or dissolved in a solvent,
The light diffusion layer 10 is formed by coating the mixture on the glass substrate 2 by a predetermined method. The refractive index of the resin (polymer matrix) is, for example, 1.5, and the refractive index of the fine particles is, for example, 1.6. Further, the thickness of the light diffusion layer 10 is uniformly controlled to, for example, 15 μm. next,
In order to fill irregularities on the surface of the light diffusion layer 10, a polymer flattening film 20 is coated with a thickness of 10 to 20 μm. After smooth polishing of the polymer flattening film 20, the electrode 8 is formed thereon. For example, a transparent conductive film such as ITO is formed by sputtering or the like to form the electrode 8. A polyimide resin or the like is applied so as to cover the electrode 8, and the surface is rubbed. Thereby, the alignment film 14 is formed. The pair of glass substrates 2 and 3 that have been subjected to a series of film forming processes in this manner are joined to each other with a predetermined gap by an adhesive or the like. In this gap, a black dichroic dye 6
, For example, is introduced by vacuum injection.

The reflection type guest-host liquid crystal display device is expected to be widely used as a display of a portable information terminal in the future because of its low power consumption and easy portability. In particular, in the integrated polarization conversion guest-host liquid crystal display device, one substrate on which a quarter-wave plate layer and an aluminum light reflection layer are formed, and a light diffusion layer in which fine particles having different refractive indices are dispersed in a polymer matrix are provided. The configuration is such that a guest-host liquid crystal is held between the other coated glass substrate. This display device controls the difference in the refractive index between the polymer matrix that constitutes the light diffusion layer located in front and the particles dispersed therein, the particle size of the particles, and the density of the particles dispersed in the polymer matrix. By doing so, it is possible to impart sufficient diffusivity to the light incident on the panel in a desired angle range, and the incident light is reflected toward the observer without loss, and a bright display can be realized. As shown in FIG. 2A, the front light diffusion layer 10 provided for diffusing light is formed by dispersing the fine particles 10b in a polymer gel or a polymer solution, and then placing the mixture on the substrate 2 in a predetermined manner. And formed by coating. However, the film-like light diffusion layer 10 formed by this method
The projections 10c and the depressions 10d are generated on the surface due to inadequate preparation environment and uneven dispersion of fine particles. In addition, there is also a problem of a coating method, and it is impossible to form the light diffusion layer 10 whose surface is practically completely smooth.
10c appears. For this reason, as shown in (B), after coating the light diffusion layer 10, it is conceivable that the surface is directly polished and flattened, and an electrode is formed thereon. However, when the light diffusion layer 10 is directly polished,
As shown in (B), the state of the polishing machine or the light diffusing layer 1
Depending on the surface state of 0, the thickness of the film to be polished in a predetermined processing time greatly varies. Therefore, the light diffusion layer 10 having stable diffusion characteristics cannot be formed.

Therefore, in the present invention, as shown in FIG. 3, a transparent flattening film 2 having no diffusivity is formed on the light diffusing layer 10.
0 is provided to fill the irregularities on the surface of the light diffusion layer 10, and then the flattening film 20 is polished. Since the light diffusion layer 10 thus formed is not directly polished at all, its thickness becomes constant, and its surface is smoothed by the flattening film 20. Specifically, as shown in (A), a coating material in which 20% of silica fine particles (refractive index 1.6) 10b is mixed with ultraviolet curing epoxy resin (refractive index 1.5) 10a,
After coating the surface of the glass substrate 2 with a blade coater, the substrate is cured by irradiation with ultraviolet light at an energy density of 1000 mj / cm ² . After that, the same UV-curable epoxy resin is applied with a blade coater at 20 μm,
Ultraviolet rays are irradiated at an energy density of 1000 mj / cm ^{2 in} the same manner as described above to form a flattened film 20. The surface of the flattening film 20 thus formed has some irregularities due to aggregation and generation of bubbles. As shown in (B), the surface of the planarizing film 20 is polished to remove the irregularities. For example, the glass substrate 2 is placed on a polishing board rotating at 60 rpm, and polished for 3 minutes while applying a load of 110 kg / 300 × 350 mm ² and supplying alumina polishing powder having a particle size of 0.8 μm. I have.

FIG. 4 is a schematic partial sectional view showing a second embodiment of the reflection type guest-host liquid crystal display device according to the present invention, and corresponds to a portion corresponding to the first embodiment shown in FIG. Reference numbers are given to obtain understanding.
Also in this embodiment, the light diffusion layer 10 is formed of a film in which the resin 10a in which fine particles 10b are dispersed is applied to the first substrate 2. The flattening film 20 is coated on the light diffusion layer 10 and has a roughened surface whose surface is roughened. The electrode 8 is formed along the rough surface of the flattening film 20. As described above, by making the boundary between the light diffusion layer 10 and the electrode 8 a rough surface structure, it is possible to reduce unnecessary reflected light due to the mismatch between the refractive indexes of the flattening film 20 and the electrode 8. Electrode 8 made of ITO etc.
Has a refractive index of 1.9, and the flattening film 20 has a refractive index of 1.9.
5 Therefore, if no countermeasure is taken, the incident light does not reach the light reflection layer 9 on the second substrate 3 side and the planarizing film 20
The light is reflected at the interface between the electrode and the electrode 8. The surface roughness of the rough surface of the planarizing film 20 is about several times the wavelength of the incident light. Further, after the electrode 8 is formed on the rough surface, when the alignment film 14 is formed, the surface becomes flat and sufficient alignment is given to the guest host liquid crystal 4. It is preferable to control between 1 μm and 2 μm. As a method of forming a rough surface, for example, a flattening film 20 is coated on the light diffusion layer 10 and then mechanically ground. At this time, a desired surface roughness can be realized by polishing using a polishing powder having a large particle diameter. For example, it is desirable to set the particle size of the polishing powder used for polishing between 2 μm and 6 μm. Alternatively, instead of mechanical grinding, the planarizing film 2 is formed by chemical etching.
The surface of 0 may be roughened.

FIG. 5A shows a reference example of a reflection type guest-host liquid crystal display device, in which only main components are shown. This display device has two upper and lower glass substrates 2,
3 is a structure in which a guest host liquid crystal 4 is held. A light reflection layer 9 is formed on the lower glass substrate 3. The upper glass substrate 2 is coated with a film in which fine particles having different refractive indices are mixed in a polymer matrix, and forms a light diffusion layer 10. After the surface of the light diffusion layer 10 is flattened, ITO is sputtered to form the electrode 8.
Is formed. An alignment film 14 is formed thereon. However, in such a configuration, a part of the incident light is reflected by the interface between the light reflection layer 10 and the electrode 8, and travels backward through the light diffusion layer 10 as it is without reaching the liquid crystal 4 below, and is emitted toward the observer. I will. The image due to the unnecessary reflected light covers an image formed by the reflected light from the light reflecting layer 9 located behind the guest-host liquid crystal 4.
Causes the black level to float when in the black display state. High contrast cannot be expected for such reasons.

On the other hand, FIG. 5B schematically shows the second embodiment shown in FIG. In this display device, a flattening film 20 is formed under a light diffusion layer 10, a rough surface having fine undulations is formed on the surface, and then an electrode 8 and an alignment film 14 are formed. Thereby, unnecessary reflection at the interface of the electrode 8 is suppressed. In order to roughen the surface of the flattening film 20, for example, the flattening film is
After forming with a thickness of m, the surface is mechanically polished with an abrasive having a particle size of 2 μm to 6 μm. For example, when polishing is performed with Ce ₂ O ₃ polishing powder having a particle size of 3 μm, unnecessary reflection can be almost completely suppressed. On the other hand, 0.8μ
In the case of polishing with an abrasive having a particle size of m, unnecessary reflection could not be completely suppressed.

Next, the operation of the second aspect of the present invention will be described in detail with reference to FIGS.
In the reference example shown in (A), a flat interface of the electrode 8 exists immediately below the light diffusion layer 10, and the incident light I0 is partially reflected due to a refractive index mismatch. This unnecessary reflected light is reflected by the light reflecting layer 9.
The light enters the observer's eyes at an emission angle θ1 following a path exactly the same as that of the reflected light from. In this case, the contrast is (I1 + I
2) It is given by / (I1 + I). I1 indicates the amount of unnecessary reflected light from the interface of the electrode 8, I2 indicates the amount of reflected light from the light reflecting layer 9 during white display, and I indicates the light reflecting layer 9 during black display.
Represents the amount of light reflected from the. On the other hand, as shown in (B), in the present invention, since the interface of the electrode 8 is in a rough state, I1 is scattered in the forward direction, and the light amount when viewed from θ1 is almost 0. Therefore, the contrast in this case is given by (I1 + I2) / I. As is clear from comparison between the two formulas, the contrast of the display device according to the present invention is remarkably improved as compared with the display device of the reference example.

[0020]

As described above, according to the first aspect of the present invention, a flattening film is coated on a light diffusion layer,
By polishing this, it is possible to form a flat light diffusion layer suitable for the orientation of liquid crystal without changing the thickness of the light diffusion layer. Further, according to the second aspect of the present invention, by making the boundary between the light diffusion layer and the electrode a rough surface, it is possible to suppress the amount of unnecessary reflected light in the case of displaying black, and it is possible to remarkably improve the contrast. . When color display is performed by combining this with a color filter, a clearer color image can be obtained as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a first embodiment of a reflection type guest-host liquid crystal display device according to the present invention.

FIG. 2 is a schematic view showing a reference example of a method for manufacturing a reflective guest-host liquid crystal display device.

FIG. 3 is a schematic view illustrating a method for manufacturing the reflective guest-host liquid crystal display device shown in FIG.

FIG. 4 is a partial sectional view showing a second embodiment of the reflective guest-host liquid crystal display device according to the present invention.

FIG. 5 is a schematic diagram for explaining the operation of the second embodiment.

FIG. 6 is a schematic view showing an example of a conventional transmission type guest host liquid crystal display device.

FIG. 7 is a schematic diagram showing an example of a conventional reflective guest-host liquid crystal display device.

FIG. 8 is a schematic view showing another example of a conventional reflective guest-host liquid crystal display device.

[Explanation of symbols]

1 ... incident, 2 ... substrate, 3 ... substrate, 4 ...
Guest host liquid crystal, 5 ... nematic liquid crystal, 6 ...
· Dichroic dye, 7 · · · quarter-wave plate layer, 8 · · · electrode, 9 · · · light reflective layer, 10 · · · light diffusion layer, 11 · · · ·
・ Reflected light, 12 ・ ・ ・ Outgoing light, 13 ・ ・ ・ Alignment film, 14
... Orientation film, 15 ... Underlayer, 16 ... Electrode, 2
0: flattening film,

Claims (6)

[Claims] 1. A transparent first substrate on which light is incident from the front, and a second substrate disposed rearward from the first substrate via a predetermined gap.
A substrate; a guest-host liquid crystal positioned on the first substrate side in the gap; a quarter-wave plate layer positioned on the second substrate side in the gap; formed on the first substrate side and the second substrate, respectively. First and second electrodes for applying a voltage to the guest-host liquid crystal; and a second substrate and the quarter-wave plate layer provided integrally with or separately from the second electrode on the second substrate side. A light-reflecting layer that is disposed between the first substrate and the first electrode and that scatters and emits light reflected from the rear toward the front; Wherein the light diffusion layer comprises a film in which a resin in which fine particles are dispersed is applied to the first substrate with a constant thickness, and the unevenness of the surface of the light diffusion layer is provided. And a flattened film polished and polished so as to fill in the first electrode. Reflective guest-host liquid crystal display device characterized by being formed on the polished surface of the planarizing film. 2. A transparent first substrate on which light is incident from the front, and a second substrate disposed rearward from the first substrate via a predetermined gap.
A substrate; a guest-host liquid crystal positioned on the first substrate side in the gap; a quarter-wave plate layer positioned on the second substrate side in the gap; formed on the first substrate side and the second substrate, respectively. First and second electrodes for applying a voltage to the guest-host liquid crystal; and a second substrate and the quarter-wave plate layer provided integrally with or separately from the second electrode on the second substrate side. A light reflection layer that intervenes between the first substrate and the first electrode and substantially reflects the light, and a light diffusion layer that is disposed between the first substrate and the first electrode and scatters and emits light reflected from behind toward the front. A reflection type guest-host liquid crystal display device comprising: a light diffusion layer comprising a film in which a resin in which fine particles are dispersed is applied to the first substrate, and the light diffusion layer is coated on the light diffusion layer; A flattening film having a roughened surface whose surface is roughened, wherein the first electrode has a roughened surface of the flattening film. Reflective guest-host liquid crystal display device characterized by being along formed. 3. An alignment film for aligning the guest-host liquid crystal is interposed at an interface between the first electrode and the guest-host liquid crystal, and the alignment film is formed on a rough surface of a planarization film. 3. The reflective guest-host liquid crystal display device according to claim 2, wherein the reflective guest-host liquid crystal display device has a film thickness sufficient to cover and smooth the first electrode. 4. The flattening film has a rough surface of 1 μm to 2 μm.
3. A surface roughness of .mu.m.
The reflective guest-host liquid crystal display device as described in the above. 5. A transparent first substrate on which light is incident from the front, a second substrate disposed rearward from the first substrate via a predetermined gap, and a guest located on the first substrate side in the gap. A host liquid crystal, a quarter-wave plate layer located on the second substrate side in the gap, and first and second layers formed on the first substrate side and the second substrate, respectively, for applying a voltage to the guest host liquid crystal. And an electrode which is provided integrally with or separate from the second electrode on the second substrate side and which is interposed between the second substrate and the quarter-wave plate layer and substantially reflects the incident light. A method for manufacturing a reflective guest-host liquid crystal display device, comprising: a reflective layer; and a light diffusion layer disposed between the first substrate and the first electrode and scattered and emitted forward to reflect light reflected from behind. A step of coating the first substrate with a resin in which fine particles are dispersed to a predetermined thickness to form the light diffusion layer; A step of applying a flattening film so as to fill irregularities on the surface of the light diffusion layer and polishing the surface smoothly; and a step of forming the first electrode on the surface of the flattened film polished smooth. A method for manufacturing a reflective guest-host liquid crystal display device, comprising: 6. A transparent first substrate on which light is incident from the front, a second substrate disposed behind the first substrate via a predetermined gap, and a guest located on the first substrate side in the gap. A host liquid crystal, a quarter-wave plate layer located on the second substrate side in the gap, and first and second layers formed on the first substrate side and the second substrate, respectively, for applying a voltage to the guest host liquid crystal. And an electrode which is provided integrally with or separate from the second electrode on the second substrate side and which is interposed between the second substrate and the quarter-wave plate layer and substantially reflects the incident light. A method for manufacturing a reflective guest-host liquid crystal display device, comprising: a reflective layer; and a light diffusion layer disposed between the first substrate and the first electrode and scattered and emitted forward to reflect light reflected from behind. Applying a resin in which fine particles are dispersed to the first substrate to form the light diffusion layer; Coating a flattening film on the surface, roughening and grinding the surface to form a rough surface, and forming the first electrode along the rough surface of the flattening film. Of manufacturing a reflective guest-host liquid crystal display device.