JPH1090674A - Reflection type guest-host liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve display brightness of a reflection type guest-host liquid crystal display device. SOLUTION: This reflection type guest-host liquid crystal display device consists of a pair of substrates 1, 2, a guest-host liquid crystal layer 3, a quarter wavelength plate layer 10 and a light-diffusing and reflecting layer 9. On the lower substrate 2 where light enters, matrix type pixel electrodes 11 and thin film transistors 8 which drive the pixels are formed as integrated. On the substrate 1 where the light reflects has a counter electrode 6 and is joined with the lower substrate 2 at a specified distance. The guest-host liquid crystal layer 3 is held between substrates 1, 2 and contains a dichroic dye 5. The quarter wavelength plate layer 10 is formed between the reflection side substrate 1 and the guest-host liquid crystal layer 3. The light-diffusing and reflecting layer 9 is formed between the reflection side substrate 1 and the quarter wavelength plate layer 10 and it diffuses and reflects the incident light entering through the incident side substrate 2 and the quarter wavelength plate layer 10.

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 technology for improving the efficiency of use of incident light by incorporating a quarter-wave plate layer and a light diffusion / reflection layer in a device.

[0002]

2. Description of the Related Art A reflection type guest-host liquid crystal display device having a built-in quarter-wave plate layer and a mirror-like light reflection layer is disclosed in, for example, Japanese Patent Application Laid-Open No. 6-222351, and FIG. Is shown. The reflective guest-host liquid crystal display device 101 includes a pair of upper and lower substrates 102 and 103, a guest-host liquid crystal layer 104 containing a dichroic dye 105, a pair of upper and lower transparent electrodes 106 and 110, and a pair of upper and lower alignment layers 1.
07 and 111, a mirror-surface light reflecting layer 108, and a quarter-wave plate layer 109. A pair of substrates 102
And 103 are made of an insulating material such as glass, quartz, or plastic. At least the upper substrate 102 located on the incident side is transparent. A guest-host liquid crystal layer 104 including a dichroic dye 105 is held in a gap between the pair of substrates 102 and 103. This guest-host liquid crystal layer 104 is composed of nematic liquid crystal molecules 104a.
As a main component. The dichroic dye 105 is a so-called p-type dye having a transition dipole moment substantially parallel to the long axis of the molecule. Although not shown, a switching element such as a thin film transistor is integrally formed on the inner surface 102a of the upper substrate 102 located on the incident side. Also, the transparent electrode 10
6 is patterned as a pixel electrode in a matrix, and is driven by a corresponding switching element. Further, the inner surface of the upper substrate 102 is covered with an alignment layer 107 made of a polyimide resin or the like. The surface of the alignment layer 107 is, for example, subjected to a rubbing treatment, so that the nematic liquid crystal molecules 104a are horizontally aligned. On the other hand, on the inner surface 103a of the lower substrate 103 located on the reflection side, a light reflection layer 108 made of aluminum or the like and a quarter-wave plate layer 109 made of a polymer liquid crystal or the like are formed in this order. The light reflection layer 108 has a mirror surface and specularly reflects incident light. Further, on the quarter-wave plate layer 109, a transparent electrode 110 serving as a counter electrode and an alignment layer 111 are formed in this order.

Next, a brief description will be given of the operation in the case of performing monochrome display using the reflective guest-host liquid crystal display device 101. In the state where no voltage is applied, the nematic liquid crystal molecules 104a are horizontally aligned and the dichroic dye 1
05 is also horizontally oriented according to this. Upper substrate 102
When light incident from the side proceeds to the guest-host liquid crystal layer 104, components of the incident light having a vibration plane parallel to the major axis direction of the molecules of the dichroic dye 105 are absorbed by the dichroic dye 105. . A component of the dichroic dye 105 having a vibration plane perpendicular to the major axis direction of the molecule passes through the guest-host liquid crystal layer 104 and is formed on the surface 103 a of the lower substrate 103 by a quarter wavelength. The light is circularly polarized by the plate layer 109 and is specularly reflected by the light reflecting layer 108. At this time, the polarization of the reflected light is reversed, passes through the quarter-wave plate layer 109 again, and becomes a component having a vibration plane parallel to the major axis direction of the molecules of the dichroic dye 105. Since this component is absorbed by the dichroic dye 105, a complete black display is obtained. On the other hand, when a voltage is applied, the nematic liquid crystal molecules 104a are vertically aligned along the direction of the electric field, and the dichroic dye 105 is vertically aligned following the direction. Light incident from the upper substrate 102 side passes through the guest-host liquid crystal layer 104 without being absorbed by the dichroic dye 105, and further passes through the light reflection layer 108 without being affected by the quarter-wave plate layer 109. reflect. The reflected light passes through the quarter-wave plate layer 109 again, and is emitted without being absorbed by the guest-host liquid crystal layer 104. Therefore, white display is obtained.

[0004]

In the conventional structure described above, the light reflection layer 108 is made of, for example, a metal film sputtered with aluminum and has a mirror surface. Therefore, the incident light is substantially specularly reflected. Therefore, when the reflective guest-host liquid crystal display device is observed from the front, only vertically incident light is specularly reflected and reaches the observer's eyes. Oblique incident light other than normal incident light does not reach the observer's eyes, resulting in a very dark screen when viewed directly from the front.

[0005]

The following means have been taken in order to solve the above-mentioned problems of the prior art. That is, the reflection type guest-host liquid crystal display device according to the present invention basically includes a pair of substrates, a guest-host liquid crystal layer, a quarter-wave plate layer, and a light diffusion reflection layer. One substrate is located on the incident side, and is integrally formed with matrix-shaped pixel electrodes and switching elements for driving the same. The other substrate is located on the reflection side, has a counter electrode formed thereon, and is joined to the one substrate via a predetermined gap.
The guest host liquid crystal layer is held in the gap and contains a dichroic dye. The quarter-wave plate layer is interposed between the other substrate located on the reflection side and the guest-host liquid crystal layer. As a characteristic feature, the light diffusion / reflection layer is interposed between the other substrate located on the reflection side and the quarter wavelength plate layer, and the quarter wavelength plate is located on the incident side from the one substrate. Incident light that has entered through the plate layer is diffusely reflected. In one embodiment, the light diffusion / reflection layer has a composite structure including a light reflection layer formed on the surface of the other substrate and a light diffusion layer formed thereon. In another embodiment, the light diffusion / reflection layer includes an uneven layer formed on the surface of the other substrate, and a light reflection layer formed on the surface of the uneven layer.

According to the present invention, a light diffusion reflection layer is used in place of the conventional light reflection layer having a mirror surface. Whereas the conventional mirror light reflection layer reflects the incident light substantially specularly, the light diffusion reflection layer of the present invention diffusely or diffusely reflects the incident light. Therefore, when the reflective guest-host liquid crystal display device is directly viewed from the front, not only the specular reflection component but also the irregular reflection component reaches the observer's eyes, so that a brighter screen than before can be obtained.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred 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 reflection type guest-host liquid crystal display device according to the present invention. Only one pixel is shown for easy understanding. As shown, the reflective guest-host liquid crystal display device includes a pair of upper and lower substrates 1 and 2, a guest-host liquid crystal layer 3, a quarter-wave plate layer 10, a light-diffusing reflective layer 9, and the like. . The lower substrate 2 is made of a transparent insulating material such as glass or quartz, and is located on the incident side. On the incident side substrate 2, a matrix of pixel electrodes 11 and switching elements for driving the pixel electrodes 11 are integrally formed. In this example, a thin film transistor 8 is used as a switching element. The surfaces of the pixel electrode 11 and the thin film transistor 8 are covered with an alignment layer 15. The upper substrate 1 is located on the reflection side and is made of an insulating material, but need not be transparent. A counter electrode 6 is formed on the reflection side substrate 1 and is joined to the incident side substrate 2 via a predetermined gap. The surface of the counter electrode 6 is aligned with the alignment layer 7.
It is covered with. The guest host liquid crystal layer 3 is held in a gap between a pair of upper and lower substrates 1 and 2 and contains a dichroic dye 5. In the present embodiment, the guest-host liquid crystal layer 3 includes nematic liquid crystal molecules 4 having a negative dielectric anisotropy.
As a main component, and is vertically aligned (homeotropically aligned) by the upper and lower alignment layers 7 and 15. Following this, the dichroic dye 5 is also vertically aligned. Therefore, when no voltage is applied, the incident light is not absorbed by the dichroic dye 5, but is reflected as it is, and a white display is obtained. Compared with the horizontal alignment (homogeneous alignment) shown in FIG. 5, the adoption of the homeotropic alignment increases the brightness of the screen in white display. However, the present invention is not limited to the homeotropic alignment, and it goes without saying that a homogeneous alignment may be adopted. When homeotropic alignment (vertical direction) is employed as in the present embodiment, the thickness of the guest-host liquid crystal layer 3 is preferably set to 3 to 10 μm.
The thickness of the guest-host liquid crystal layer 3 is a pair of upper and lower substrates 1,
2 is defined by the gap size.

The quarter-wave plate layer 10 is interposed between the reflection-side substrate 1 and the guest-host liquid crystal layer 3. Specifically, the quarter-wave plate layer 10 is formed on the reflection-side substrate 1, and the above-described counter electrode 6 is formed thereon. If the quarter-wave plate layer 10 is to be formed on the incident side substrate 2, it must be interposed between the thin film transistor 8 and the pixel electrode 11. In this case, in order to connect the pixel electrode 11 and the thin film transistor 8 to each other, a contact hole must be opened in the intervening quarter-wave plate layer 10, which complicates the manufacturing process. Further, in order to open the contact hole, photolithography or etching must be performed, and the quarter-wave plate layer 10 is damaged. On the other hand, in the present embodiment, the quarter-wave plate layer 10 is formed on the reflection-side substrate 1, so that no additional processing such as opening of a contact hole is required, and the quarter-wave plate layer 10 is simply formed on the incidence-side substrate 1. What is necessary is just to form a film.

Further, the light diffusion / reflection layer 9 which is a characteristic element of the present invention is interposed between the reflection-side substrate 1 and the quarter-wave plate layer 10. The light diffuse reflection layer 9 is a quarter-wave plate layer 1
The incident light that enters through 0 is diffusely or diffusely diffusely reflected. In the present embodiment, the light diffusion / reflection layer 9 has a composite structure including a light reflection layer 9a formed on the surface of the reflection side substrate 1 and a light diffusion layer 9b formed thereon. The light reflection layer 9a is made of, for example, a sputtered film or a vacuum deposited film of aluminum, and has a substantially mirror surface. The light diffusion layer 9b is formed, for example, by dispersing transparent fine particles in a transparent resin. The refractive index of the transparent fine particles is significantly different from that of the transparent resin, and strongly diffuses or scatters light. As described above, by overlapping the light reflection layer 9a and the light diffusion layer 9b, the light diffusion reflection layer 9 having excellent light scattering properties can be obtained. By using such a light diffusion / reflection layer 9, the brightness of the screen during white display can be remarkably improved. If a black dye is used as the dichroic dye 5, a desired black and white display can be obtained. If a micro color filter is provided on one of the upper and lower substrates 1 and 2, full-color display can be performed instead of monochrome display. The micro color filter is made up of a set of segments that match the individual pixel electrodes 11 and are colored in three primary colors. The segments are colored in three primary colors of red, green and blue.
In some cases, a micro color filter colored in three primary colors of yellow, cyan, and magenta may be used.
This micro color filter can be provided between the quarter-wave plate layer 10 and the light diffusion layer 9b. Alternatively, the light diffusion layer 9b itself may be colored in three primary colors corresponding to each pixel electrode 11. Alternatively, a micro color filter may be provided directly below the pixel electrode 11 formed on the lower substrate 2.

Referring to FIG. 1, a method of manufacturing a reflection type guest-host liquid crystal display device according to the present invention will be described.
First, the thin film transistor 8 is integratedly formed on the surface of the substrate 2 located on the incident side. Specifically, after a high melting point metal film is formed on the surface of the substrate 2 made of glass, quartz, or the like, the gate electrode 16 is processed by patterning in a predetermined shape. Silicon oxide or silicon nitride is deposited by CVD or the like so as to cover the gate electrode 16 to form a gate insulating film 17. Further, a semiconductor thin film 18 made of polycrystalline silicon or the like is formed thereon by CVD or the like. This semiconductor thin film 18 is patterned in an island shape according to the shape of the element region of the thin film transistor 8. A stopper 19 made of silicon oxide or the like is patterned on the semiconductor thin film 18 in alignment with the gate electrode 16. Using this stopper 19 as a mask, impurities are implanted into the semiconductor thin film 18 by ion doping or ion implantation. Thus, a thin film transistor 8 having a bottom gate structure is obtained. Note that the present invention is not limited to this, and a thin film transistor having a top gate structure may be used as a switching element instead of a thin film transistor having a bottom gate structure. Or,
A two-terminal element such as a MIM may be used instead of the thin film transistor (TFT). PSG or the like is deposited so as to cover the thin film transistor 8 to form an interlayer insulating film 20. afterwards,
A pair of contact holes are opened in the interlayer insulating film 20.
Next, after sputtering aluminum or the like, the wiring 21 is processed by patterning in a predetermined shape. This wiring 2
1 is electrically connected to the source region of the thin film transistor 8 and supplies an image signal. Subsequently, a transparent conductive film such as ITO is formed by sputtering, and then patterned into a predetermined shape to process the pixel electrode 11. This pixel electrode 11 is electrically connected to the drain region of the thin film transistor 8 via a contact hole. After that, the alignment layer 15 is formed so as to cover the pixel electrode 11. For example, a desired alignment layer 15 can be obtained by forming a polyimide film for vertical alignment. In some cases, a silane coupling agent for vertical alignment may be used instead of the polyimide film.
As described above, the substrate 2 on the incident side is formed. The substrate 2 is divided into a pixel electrode 11 serving as an effective aperture of the pixel and a thin film transistor 8 for blocking incident light. In some cases, a light-shielding pattern may be formed on the back surface of the substrate 2 to shield the thin film transistor 8 from incident light.

Next, a process of manufacturing the substrate 1 on the reflection side will be described. First, a light reflection layer 9a is formed on the surface of the substrate 1 by sputtering aluminum or the like. The light reflection layer 9a simply reflects the incident light on a specular surface. Next, the light diffusion layer 9b is formed so as to overlap the light reflection layer 9a. For example, an optical material in which transparent fine particles are dispersed in a transparent resin such as an acrylic resin is applied to form the light diffusion layer 9b. The transparent resin and the transparent fine particles have significantly different refractive indexes, and have excellent light diffusing properties. The light diffusion / reflection layer 9 is obtained by the composite structure of the light reflection layer 9a and the light diffusion layer 9b. The light diffusion / reflection layer 9 diffusely reflects incident light entering from the periphery during white display, and provides a bright display. Thereafter, the process proceeds to the process of forming the quarter-wave plate layer 10 on the light diffusion layer 9b. First, the surface of the light diffusion layer 9b is rubbed along a predetermined direction. The rubbing direction is such that the liquid crystal molecules 4
Is set to form an angle of 45 ° with the direction in which it falls horizontally. A polymer liquid crystal is applied in a predetermined thickness on the rubbed light diffusion layer 9b. This polymer liquid crystal is a material capable of phase transition between a high temperature side nematic liquid crystal phase and a low temperature side glass solid phase at a predetermined dislocation point. For example, this polymer liquid crystal is in a glassy state at room temperature, and is preferably a main chain type or a side chain type having a dislocation point at 100 ° C. or higher.
This polymer liquid crystal is a transparent substance that does not optically absorb in the visible region. After dissolving this polymer liquid crystal in an organic solvent (for example, a mixed solution of cyclohexane and n-butanone),
It is applied to the surface of the light diffusion layer 9b by spin coating. In addition, you may apply by using dipping (immersion) or screen printing etc. instead of spin coating. When spin coating is performed, conditions such as the concentration of the solution and the number of spin rotations are appropriately set so that the thickness of the formed thin film causes a phase difference of λ / 4 in the visible light region. Here, λ is the wavelength of the incident light. Generally, the thickness of this thin film is calculated for normally incident light. Therefore, for obliquely incident light, the phase difference slightly deviates from λ / 4. Thereafter, a temperature treatment is performed, and the substrate 1 is once heated to a temperature equal to or higher than the dislocation point, then cooled to room temperature equal to or lower than the dislocation point, and the formed polymer liquid crystal is aligned in the above-described rubbing direction to form a quarter-wave plate layer. Form 10. For example, heating and cooling are performed on a polymer liquid crystal material having a dislocation point of 100 ° C. or higher and liquid crystal molecules introduced into the main chain or side chain of the polymer. In the film formation stage, the liquid crystal molecules contained in the polymer liquid crystal are in a random state, but after slow cooling, the liquid crystal molecules are aligned along the rubbing direction, and a desired uniaxial optical anisotropy can be obtained. Specifically, the substrate 1 on which the polymer liquid crystal has been formed is put into an oven set to a nematic phase temperature or an isotropic phase temperature in advance and heated. Then, cool slowly and return to room temperature. As a result, the coated polymer liquid crystals are aligned in the rubbing direction. Thereafter, a transparent conductive film such as ITO is entirely formed on the quarter-wave plate layer 10 by sputtering or the like to form the counter electrode 6. Further, the surface is covered with an alignment layer 7 for vertical alignment such as a polyimide film. The reflection-side substrate 1 thus processed is joined to the incident-side substrate 2 via a predetermined gap. When the guest-host liquid crystal layer 3 containing the dichroic dye 5 is injected into the gap between the two substrates 1 and 2, the reflection-type guest-host liquid crystal display device is completed.

Next, the operation of the reflective guest-host liquid crystal display device according to the present invention will be described with reference to FIG. FIG. 2 shows a voltage application state, in which the pixel electrode 11 and the counter electrode 6
And the liquid crystal molecules 4 and the dichroic dye 5 interposed between them have shifted from the vertical alignment state to the horizontal alignment state. Light incident from the substrate 2 side passes through the opening region where the pixel electrode 11 is formed, while is blocked in the region where the thin film transistor 8 is formed. The incident light passing through the pixel electrode 11 enters the guest-host liquid crystal layer 3 containing the dichroic dye 5 inclined substantially horizontally by the electric field. Among the incident light, a component having a vibration component parallel to the long axis of the dichroic dye 5 is absorbed by the dichroic dye 5 and vibrates in a direction perpendicular to the long axis direction (perpendicular to the paper). The components pass through the guest-host liquid crystal layer 3. Further, this component is reflected by the light diffusion / reflection layer 9 after passing through the quarter-wave plate layer 10, passes through the quarter-wave plate layer 10 again, and returns to the guest-host liquid crystal layer 3. The vibration direction rotates 90 °. The rotated vibration direction matches the vibration direction absorbed by the dichroic dye 5, and is absorbed here, so that a black display is obtained.

FIG. 3 is a schematic diagram showing a reflection state of incident light. 4A shows a case where the light diffusion layer 9b is not used, and the incident light is specularly reflected by the light reflection layer 9a via the quarter-wave plate layer 10. FIG. When the reflection type liquid crystal display device is directly viewed from the front, only vertically incident light is specularly reflected and reaches the eyes of the observer. Since the obliquely incident light does not reach the observer's eyes, the screen becomes very dark. As shown in the figure, only reflected light included in the range indicated by the solid angle Ω is effective for display. However, in this case, since the effective reflected light passes vertically through the approximately quarter-wave plate layer 10, no error occurs in the polarization conversion function. In other words, the quarter-wave plate layer 10 is generally designed so as to correctly give a phase difference of λ / 4 to vertically incident light. Since the obliquely incident light deviates from this design value, an ideal polarization conversion cannot be obtained. As shown in (A),
If only specular reflection is used for display, only light that has undergone substantially ideal polarization conversion when viewed directly from the front reaches the eyes of the observer.

FIG. 2B shows a light diffusion layer 9b interposed between the light reflection layer 9a and the quarter-wave plate layer 10 according to the present invention. In this case, since the light that reaches the observer's eyes includes the irregular reflection component in addition to the irregular surface reflection component in the solid angle Ω,
The display becomes very bright. However, in this case, since oblique light in addition to vertical light also reaches the observer's eye, an error occurs in polarization conversion for the oblique light. In general, in order to perform polarization conversion for rotating the oscillation direction of incident light by 90 °, it is necessary to accurately impart a phase difference of λ / 4 to the incident light. In other words, d is set so that the retardation (Δn × d) of the quarter-wave plate layer 10 becomes λ / 4.
Note that d is the thickness of the quarter-wave plate layer 10, and Δn indicates the refractive index anisotropy. If only the vertically reflected light is used for the display as shown in (A), there is no change in retardation. However, in the case of (B), in addition to the vertically reflected light, the obliquely reflected light also reaches the observer's eye, so that the value of d that defines the retardation takes various values, so that the effect of the polarization conversion on the incident light is obtained. Slightly fades. However, when the light diffusing layer 9b was actually interposed, the effect of the effect of the polarization conversion was almost inconspicuous, and the brightness of the display screen was significantly improved. It is presumed that this is because the viewing angle of the polymer liquid crystal constituting the quarter-wave plate layer 10 is wide. As described above, according to the present invention, by interposing the light diffusion layer 9b, the brightness of the white display can be significantly increased without lowering the contrast of the black display.

FIG. 4 is a schematic partial sectional view showing a second embodiment of the reflective guest-host liquid crystal display device according to the present invention. Parts corresponding to those in the first embodiment shown in FIG. 1 are denoted by corresponding reference numerals to facilitate understanding. In the present embodiment, the light diffusion / reflection layer 9 includes an uneven layer 9 c formed on the surface of the substrate 1, a light reflection layer 9 a formed on the surface of the uneven layer 9 c, and a planarization formed thereon. And a layer 9d. The uneven layer 9c can be formed by, for example, etching or sandblasting the surface of the substrate 1. A metal such as aluminum is vapor-deposited thereon to form a light reflecting layer 9.
a is formed. In this case, the light diffusion / reflection layer can be formed more easily than the light diffusion / reflection layer shown in FIG. Note that the formation of the quarter-wave plate layer 10 is facilitated by forming the flattening layer 9d on the light reflecting layer 9a having unevenness. The depth dimension of the unevenness is, for example, several μm
, Good light scattering characteristics can be obtained, and the light diffusion / reflection layer 9 exhibits white.

[0016]

As described above, according to the present invention,
A light-diffusing reflective layer is provided between the reflection-side substrate and the quarter-wave plate layer, and diffusely reflects incident light entering from the incident-side substrate through the quarter-wave plate layer. . As a result, the display brightness of the reflective guest-host liquid crystal display device can be significantly improved. In the present invention, the substrate on which the thin film transistor and the pixel electrode are formed is set to the incident side, and the substrate on which the counter electrode is formed is positioned on the reflection side. Since the quarter-wave plate layer is formed on the reflection-side substrate, the manufacturing process can be extremely simplified as compared with the case where the quarter-wave plate layer is formed on the incident-side substrate.

[Brief description of the drawings]

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

FIG. 2 is a partial cross-sectional view for explaining the operation of the first embodiment shown in FIG.

FIG. 3 is a schematic view for explaining a function of a light diffusion reflection layer.

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 cross-sectional view illustrating an example of a conventional reflective guest-host liquid crystal display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reflection side substrate, 2 ... Incident side substrate, 3 ... Guest host liquid crystal layer, 4 ... Liquid crystal molecule, 5 ... Dichroic dye, 6 ... Counter electrode,
Reference Signs List 8: thin film transistor, 9: light diffusion reflection layer, 9a: light reflection layer, 9b: light diffusion layer, 9c: uneven layer, 10: quarter wavelength plate layer, 11: pixel electrode, 18: semiconductor thin film

Claims (3)

[Claims] A first substrate on which a matrix-shaped pixel electrode and a switching element for driving the pixel electrode are located on an incident side; and a counter electrode located on a reflection side is formed. The other substrate bonded to the one substrate through the gap, the guest-host liquid crystal layer held in the gap and containing a dichroic dye, and the other substrate positioned on the reflection side. A quarter-wave plate layer interposed between the guest-host liquid crystal layer and a quarter-wave plate layer interposed between the other substrate positioned on the reflection side and the quarter-wave plate layer and positioned on the incident side A reflection-type guest-host liquid crystal display device comprising: a light-diffusing reflection layer that diffusely reflects incident light that has entered from the one substrate through the quarter-wave plate layer. 2. The reflection type according to claim 1, wherein the light diffusion / reflection layer has a composite structure including a light reflection layer formed on the surface of the other substrate and a light diffusion layer formed thereon. Guest host liquid crystal display. 3. The reflection type guest according to claim 1, wherein the light diffusion / reflection layer comprises an uneven layer formed on the surface of the other substrate, and a light reflection layer formed on the surface of the uneven layer. Host liquid crystal display.