JPH11184389A - Reflection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give a reflection type display device a lighting structure which makes it possible to observe an image in a dark environment without spoiling image quality in a light environment. SOLUTION: The reflection type display device consists of a panel 0, a light guide plate 20, a light source 30, and a light refracting layer 40. The light guide plate 20 is arranged outside the panel 0. The light source 30 is arranged at the end part of the light guide plate 20 and emits illumination light when needed. The light guide plate 20 normally transmits external light and makes it incident on the panel 0 and projects its reflected external light, and also guides and makes the illumination light at need incident on the panel 0 and projects its reflected illumination light. The light refracting layer 40 which has an uneven surface is interposed between the light guide plate 20 and panel 0 and diffuses and refracts the illumination light. Consequently, a moire is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type display device which performs display using external light such as natural light. More specifically, the present invention relates to an illumination structure of a reflective display device which is used as an auxiliary when external light is scarce.

[0002]

2. Description of the Related Art There are various modes in a display device, and a TN mode or an STN mode using a nematic liquid crystal which is twist-oriented or super-twist-oriented is mainly used at present. However, these modes require a pair of polarizing plates in terms of operation principle, and because of their light absorption, a low transmittance and a bright display screen cannot be obtained. 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 anisotropy of the absorption coefficient 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 to the liquid crystal molecules, so 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. 11 shows HEILMEI.
1A shows the structure of an ER) type guest-host liquid crystal display device, wherein FIG. 1A shows a state where no voltage is applied, and FIG. This liquid crystal display device uses a p-type dye and a nematic liquid crystal (Np liquid crystal) having a positive dielectric anisotropy. The p-type dichroic dye has an absorption axis substantially parallel to the molecular axis, strongly absorbs the polarized light component Lx parallel to the molecular axis,
The polarized light component Ly perpendicular thereto is hardly absorbed.
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. On the other hand, in the voltage application state shown in (B), the Np liquid crystal having a positive dielectric anisotropy rises in response to an electric field, and the p-type dye is aligned in the vertical direction accordingly. For this reason, the liquid crystal display device is almost colorless only by slightly absorbing the polarization component Lx. 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 polarized component Ly is removed to improve the contrast.

The guest-host liquid crystal display device shown in FIG. 11 is of a transmission type, but a reflection type is also known. For example, FIG.
As shown in FIG. 2, 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 reflector are attached to the output side. In this system, two polarization components Lx and Ly orthogonal to each other are rotated by 90 degrees in the forward and backward directions by a quarter-wave plate, and the polarization components are switched. Therefore (A)
In the off state (absorption state) shown in FIG.
y will be absorbed in either the incident light path or the reflected light path. In the ON state (transmission state) shown in FIG. 2B, neither of the polarization components Lx and Ly is hardly absorbed. Thereby, the utilization efficiency of incident light can be improved.

[0005]

In the transmission type display device shown in FIG. 11, a panel holding a liquid crystal as an electro-optical material is formed between a pair of transparent substrates, and a light source for illumination (back) is provided on the back surface. Light) and observe the image from the front of the panel. In the case of the transmission type, a backlight is indispensable and, for example, a cold cathode tube or the like is used. For this reason, when viewed as a whole display, the backlight displays most of the power, which is not suitable for a display of a portable device. On the other hand, in the reflection type shown in FIG.
While a reflector is disposed on the back of the panel, external light such as natural light is incident on the panel from the front, and the reflected light is used to observe an image from the front. Unlike the transmissive type, which does not use a light source for backlighting, the reflective type requires relatively low power consumption and is suitable for a display of a portable device. However, the reflective display device cannot observe an image in an environment where external light is poor, such as at night, and is a problem to be solved.

[0006]

The following means have been taken in order to solve the above-mentioned problems of the prior art. That is, the reflective display device according to the present invention includes a panel, a light guide plate, and a light source as a basic configuration. The panel includes a transparent first substrate located on the side of incidence of external light,
A second substrate joined to the substrate and positioned on the reflection side, an electro-optical material held in the gap, and an electrode formed on at least one of the first and second substrates and applying a voltage to the electro-optical material; I have. The light guide plate is made of a transparent material and is disposed outside the first substrate. A light source is disposed at an end of the light guide plate,
Generates illumination light as needed. As a characteristic feature, the light guide plate normally passes through the external light, enters the first substrate, and emits the external light reflected from the second substrate, and guides the illumination light as necessary to form the second light. The illumination light is incident on one substrate and reflected from the second substrate. The light guide plate has a flat portion divided into a strip shape and an inclined step portion located between the flat portions, and the thickness gradually decreases from the end where the light source is located toward the front. ing. The light guide plate reflects the illumination light guided toward the front at each step portion and enters the first substrate, and emits the illumination light reflected from the second substrate from each plane portion. As a further feature,
A light refraction layer having an uneven surface is interposed between the light guide plate and the first substrate, and diffusely refracts illumination light.

The refraction layer is made of, for example, an optical sheet in which microprisms or microlenses are arranged in stripes. The angle of inclination of the uneven surface is set so that the refraction layer refracts the illumination light at an angle larger than the first-order diffraction of the illumination light by the light guide plate. In an embodiment of the present invention,
The panel uses a guest-host liquid crystal layer in which a dichroic dye serving as a guest is added to liquid crystal serving as a host as an electro-optical material. In this case, the panel has a light reflection layer located on the second substrate side and reflecting external light, and a quarter-wave plate layer interposed between the guest host liquid crystal layer and the light reflection layer.

According to the present invention, the light guide plate is arranged on the surface of the reflection type panel, and the light source is arranged at the end. In a dark environment, the light source is turned on, and illumination light is incident on the panel side via the light guide plate to display an image. In a bright environment, the light source is turned off, and an image is projected using external light directly through a transparent light guide plate. The light guide plate is basically transparent and does not hinder the observation of an image even in a bright environment. As described above, according to the present invention, the light source only needs to be turned on when necessary, and the power consumption of the entire display can be significantly reduced, which is suitable for a display of a portable device. In addition to the basic functions described above, the present invention devises to enhance the image quality especially in a dark environment. That is, a light refraction layer having an uneven surface is interposed between the light guide plate and the panel, whereby the illumination light is refractively diffused. This light refraction layer can suppress interference fringes caused by the periodic prism structure (diffraction grating) of the light guide plate, and enables high quality display.

[0009]

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 an embodiment of the reflective display device according to the present invention.
As shown in the drawing, the reflective display device includes a panel 0, a light guide plate 20, a light source 30, and a light refraction layer 40 as a basic configuration. The panel 0 is a transparent first substrate 1 located on the outside light incident side, is bonded to the first substrate 1 via a predetermined gap, and is held in the gap between the second substrate 2 and the two substrates 1 and 2 on the reflection side. And an electrode 1 formed on each of the first substrate 1 and the second substrate 2 for applying a voltage to the electro-optical material.
0 and 11 are provided. Depending on the driving method, an electrode may be formed on at least one of the two substrates 1 and 2. The light guide plate 20 is made of, for example, an injection-molded product made of a transparent material such as an acrylic resin, and is disposed outside the first substrate 1.
The light source 30 is provided at an end of the light guide plate 20 and generates illumination light as needed. The light source 30 is formed of, for example, a cold cathode tube, and is called a so-called edge light. In order to improve the illumination efficiency of the edge light, a reflecting mirror 31 is arranged behind the cylindrical light source 30. In such a configuration, the light guide plate 2
0 means that normal light is transmitted through the first substrate 1 and the second
The external light reflected from the substrate 2 is emitted, and the illumination light is guided as needed to be incident on the first substrate 1 and the illumination light reflected from the second substrate 2 is emitted.

The light guide plate 20 has a flat portion 2 divided into strips.
2 and the inclined step portion 21 located between the flat portions 22
And the thickness gradually decreases from the end where the light source 30 is located toward the front. The light guide plate 20 totally reflects the illumination light guided in the horizontal direction toward the front at each step portion 21 and enters the first substrate 1, and also applies the illumination light reflected from the second substrate 2 to each plane portion 22. Emitted from The step portion 21 of the light guide plate 20 is, for example, 45
It is inclined at an angle of °. In the drawing, this inclination angle is represented by θ. FIG. 1 shows a use state of a reflective display device in a dark environment, and a light source 3 constituting an edge light.
0 is lit. The illumination light emitted from the light source 30 illuminates the panel 0 via the light guide plate 20. That is, the light guide plate 20
The illumination light that travels in the horizontal direction inside the light guide plate 20 is totally reflected by the inclined step portion 21 and is incident on the first substrate 1 side, while the illumination light reflected from the second substrate 2 is 2
2 is emitted.

The light refraction layer 40 has an uneven surface, is interposed between the light guide plate 20 and the first substrate 1, and diffusely refracts illumination light. The light refraction layer 40 is made of, for example, an optical sheet in which micro prisms or micro lenses are arranged in a stripe shape. The light refraction layer 40 can remove moiré by refracting illumination light totally reflected from the light guide plate 20 to the panel 0. In this moire, the light guide plate 20 is
It has one periodic structure and is generated to function as a diffraction grating. Moire is removed with a light refraction layer 40 interposed in order to significantly reduce the image quality. That is, since the illumination light totally reflected from the step portion 21 of the light guide plate 20 is refracted on the uneven surface of the light refraction layer 40, the correlation is reduced and moire is not formed.

The panel 0 uses a guest-host liquid crystal layer 3 in which a dichroic dye 5 serving as a guest is added to a liquid crystal 4 serving as a host as an electro-optical material. However, the present invention is not limited to the guest-host liquid crystal, and other materials can be used as the electro-optical material. The panel 0 includes a light reflection layer 8 and a quarter-wave plate layer 9. The light reflection layer 8 is located on the second substrate 2 side and scatters and reflects external light. The quarter-wave plate layer 9 is interposed between the guest host liquid crystal layer 3 and the light reflection layer 8. Hereinafter, the structure of the panel 0 will be described in detail. The guest host liquid crystal layer 3 is composed of a mixture of a nematic liquid crystal 4 and a dichroic dye 5, and is homogeneously aligned by upper and lower alignment films 6 and 7. A light reflection layer 8 is provided in the gap between the two substrates 1 and 2 on the second substrate 2 side. Further, a quarter-wave plate layer 9 is interposed between the guest host liquid crystal layer 3 and the light reflection layer 8. Electrodes 10 and 11 for applying a voltage to the guest-host liquid crystal layer 3 are formed on the first substrate 1 side and the second substrate 2 side, respectively.

The light reflecting layer 8 has irregularities on the surface and has light scattering properties. Accordingly, not only is the paper white appearance preferable as a display background, but also the incident light is reflected in a relatively wide angle range, so that the viewing angle is enlarged, the display is easy to see, and the brightness of the display is increased in a wide viewing angle range.
A transparent flattening layer 12 that fills in irregularities is interposed between the light reflecting layer 8 and the quarter-wave plate layer 9. The quarter-wave plate layer 9 is made of a polymer liquid crystal material 13 uniaxially oriented along the surface of the planarizing layer 12. Note that a base alignment film 14 is provided between the flattening layer 12 and the quarter-wave plate layer 9 in order to uniaxially align the polymer liquid crystal material 13. The light reflecting layer 8 is composed of a resin film 15 having unevenness and a metal film 16 such as aluminum formed on the surface thereof. The resin film 15 is a photosensitive resin film having irregularities patterned by photolithography.

The photosensitive resin film 15 formed on the surface of the second substrate 2 is made of, for example, a photoresist and is applied to the entire surface of the substrate. This is exposed through a predetermined mask, and is patterned into, for example, a cylindrical shape. Then, by heating and performing reflow, the uneven shape can be formed stably. A metal film 16 made of aluminum or the like having a desired film thickness and good light reflectivity is formed on the surface of the concavo-convex shape thus formed. If the depth dimension of the unevenness is set to several μm, good light scattering characteristics can be obtained, and the light reflection layer 8 exhibits white. A flattening layer 12 is formed on the surface of the light reflecting layer 8 to fill the irregularities. The flattening layer 12 is preferably made of a transparent organic material such as an acrylic resin. With the planarization layer 12 interposed, the formation of the base alignment film 14 and the rubbing process can be stably performed. Therefore, the quarter-wave plate layer 9 can be formed with high accuracy. An alignment film 7 is formed on the quarter-wave plate layer 9. The guest-host liquid crystal layer 3 is homogeneously aligned (horizontally aligned) by the alignment film 7 formed on the second substrate 2 side and the alignment film 6 formed on the first substrate 1 side. Alternatively, the guest-host liquid crystal layer 3 may be homeotropically aligned (vertical alignment).

Next, a brief description will be given of the operation when black-and-white display is performed using this reflective guest-host liquid crystal display device. When no voltage is applied, the nematic liquid crystal 4 is horizontally oriented, and the dichroic dye 5 is similarly oriented.
When the illumination light incident from the upper first substrate 1 advances to the guest-host liquid crystal layer 3, a component of the illumination light having a vibration plane parallel to the long axis of the molecules of the dichroic dye 5 becomes a dichroic dye. Absorbed by 5. The component of the dichroic dye 5 having a vibration plane perpendicular to the major axis direction of the molecule passes through the guest-host liquid crystal layer 3 and forms a quarter formed on the surface of the lower second substrate 2. The light is converted into circularly polarized light by the wavelength plate layer 9 and is reflected by the light reflecting layer 8.
At this time, the polarization of the reflected light is reversed, passes through the quarter-wave plate layer 9 again, and becomes a component having a vibration plane parallel to the major axis direction of the molecules of the dichroic dye 5. Since this component is absorbed by the dichroic dye 5, an almost complete black display is obtained. On the other hand, when a voltage is applied, the nematic liquid crystal 4 is vertically oriented along the direction of the electric field, and the dichroic dye 5 is similarly oriented. Illumination light incident from the upper first substrate 1 side passes through the guest-host liquid crystal layer 3 without being absorbed by the dichroic dye 5, and is not substantially affected by the quarter-wave plate layer 9. The light is reflected by the light reflection layer 8. The reflected light passes through the quarter-wave plate layer 9 again and exits without being absorbed by the guest-host liquid crystal layer 3. Therefore, white display is obtained.

FIG. 2 shows how the reflective guest-host liquid crystal display device shown in FIG. 1 is used in a bright environment. In a bright environment, since there is sufficient external light such as natural light, display is performed using this. Therefore, the light source 30 is turned off. Thereby, the power consumption of the entire display can be reduced. The light guide plate 20 transmits external light incident from the viewer side as it is, enters the first substrate 1, and emits external light reflected from the second substrate 2 from the flat portion 22.
The light guide plate 20 is basically transparent and does not hinder any observation of the display.

As described above, the reflection type display device requires less power consumption and is expected as a display of an information terminal. However, unlike a transmissive display device using a backlight, a reflective display device cannot see a screen in a dark environment. In order to solve this problem, the present invention uses a light guide plate. FIG. 3 shows a typical structure of the light guide plate according to the present invention. As described repeatedly, this light guide plate 2
0 is set on the front glass substrate of the reflective panel. The light guide plate 20 has a stepped portion 21 having an inclination angle of, for example, 45 °.
And a plane portion 22 parallel to the glass substrate of the panel, and is a diffraction grating having a periodic structure.

FIG. 4 schematically shows a reference example in which the light guide plate 20 shown in FIG. In the vicinity of the end surface 25 of the light guide plate 21, a light source such as a cold cathode tube is disposed. The illumination light generated from the cold-cathode tube enters horizontally from the end face 25, and is almost totally reflected vertically downward by the stepped portion 21 having a 45 ° inclined surface. The reflected light can illuminate the reflective panel 0 from the front side. In a bright place, the screen is observed with environmental illumination (external light), while in a dark environment, the cold cathode fluorescent lamp is turned on to illuminate the panel 0 and the screen can be observed. However, when the light guide plate 20 is directly installed on the front surface of the reflective panel 0, interference fringes occur due to the periodic structure of the light guide plate 20, and the screen becomes difficult to see. When the illumination light emitted from the light source is totally reflected vertically downward by the light guide plate 20, it is diffracted due to the periodic structure of the light guide plate 20, and primary light, secondary light, etc. are generated in addition to zero-order light. . The illumination light reflected from the panel 0 passes through the light guide plate 20 again, but is also diffracted at this time to generate zero-order light, primary light, and so on. Zero-order light and first-order light generated by the two diffractions interfere with each other, and bright and dark stripes are visually recognized as overlapping on the screen. As a result, the visibility of the display is impaired. In particular, when the screen is observed at a position inclined from the front of the panel 0 to the side opposite to the light source, the interference fringes become noticeable. That is, when the line of sight of the observer is inclined to the side facing the inclined surface of the step portion 21, the interference fringes become conspicuous. The greater the inclination of the line of sight, the sharper the interference fringes.

FIG. 5 schematically shows the occurrence of moire. (A) shows a first substrate 1 made of glass or the like and ITO
1/10 interface with the electrode 10 made of a transparent conductive film such as
(B) is a diagram focusing on the original illumination light reflected by the light reflection layer 8 formed on the second substrate. In each case, the light guide plate 20 is represented as if it were folded back on the reflection surface, which facilitates understanding. As shown in FIG. 1A, the light guide plate 20 has a step portion 21 and a plane portion 22 periodically arranged to form a kind of diffraction grating 201. The illumination light that has passed through the diffraction grating 201 undergoes specular reflection at the interface 1/10, and passes through the light guide plate 20 again. At this time, the light guide plate 20 functions as the diffraction grating 202. The pair of diffraction gratings 201 and 202 are complementary to each other. When viewed equivalently, the illumination light passes through the diffraction gratings 201 and 202 before reaching the observer.
The first diffracted light and the second diffracted light interfere with each other to form moire. For example, the illumination light is split by the diffraction grating 201 into zero-order diffracted light and first-order diffracted light. These diffracted lights are diffracted again by the diffraction grating 202 and split into zero-order diffracted light and first-order diffracted light. In particular, the first-order diffracted light generated from the first zero-order diffracted light and the zero-order diffracted light obtained from the first first-order diffracted light have the same total order, and strongly interfere with each other. The parallel incident light from the cold cathode tube is reflected by the step 22 of the light guide plate and proceeds to the interface 1/10 as it is. The light specularly reflected at this interface is parallel light. The parallel incident light and the parallel reflected light pass through almost the same path and interfere with each other. This interference is what causes moiré.

On the other hand, as shown in FIG. 2B, the illumination light reflected by the light reflecting layer 8 having a high diffusivity has no interference. The illumination light reflected by the light reflection layer 8 is a mixture of the zero-order diffracted light and the first-order diffracted light, has no coherence, and does not cause moire.

In order to suppress the above-mentioned moiré, the present invention employs the structure of the light guide plate 20 shown in FIG. That is, the step portion 22 and the flat portion 21 are periodically formed on the front surface side of the light guide plate 20, while the light refraction layer 40 is provided on the rear surface side. In the present embodiment, the light guide plate 20 and the light refraction layer 40 have an integral structure.
May be separated from each other so as to overlap each other. The light refraction layer 40 has an uneven surface 41, and the light guide plate 2
It intervenes between 0 and the panel and diffusely refracts the illumination light. The light refraction layer 40 is formed by arranging microprisms 42 or microlenses in a stripe shape. Light guide plate 2
Zero step portions 22 are also arranged in a stripe shape. The stripes of the step 22 and the stripes of the microprism 42 are orthogonal to each other.

FIG. 7 is an explanatory view schematically showing an optical function of the light refraction layer-integrated light guide plate 20 shown in FIG.
The parallel incident light (illumination light) from the light source passes through the step 21 of the light guide plate.
Is totally reflected vertically downward. The parallel reflected light is refracted by the inclined surface 41a of the micro prism 42. Since the traveling direction after refraction changes in various ways, it becomes pseudo diffused light. When the light reaches the interface between the glass substrate and the transparent electrode, the coherence disappears. Theoretically, specularly reflected light from any interface has no coherence and no moiré occurs. On the other hand, the light guide plate 20 of the reference example shown in FIG. 8 does not include the light refraction layer, and the parallel incident light from the light source enters the panel as parallel reflected light via the step portion 21. Interference is maintained.

The light refraction layer can be an optical sheet separate from the light guide plate. FIG. 9 shows an optical sheet in which microprisms are arranged in a stripe shape. (A) shows a cross-sectional shape of the optical sheet 40a, and (B) shows a planar shape.
As shown in the figure, the optical sheet 40a has an anisotropic structure in which microprisms 42 extending in a stripe shape are arranged at a predetermined pitch along a direction orthogonal to the stripes. The thickness of the optical sheet 40a is, for example, about one hundred and several tens μm. The optical sheet 40a is used by being inserted between the light guide plate and the panel.

FIG. 10 shows an embodiment of the reflection type display device according to the present invention, in which the optical sheet 40a shown in FIG. The light guide plate 20 is 90 mm × 120 according to the screen size.
mm. The maximum thickness is 3.2 mm and the minimum thickness is 0.2 mm. The acrylic resin plate was machined with a diamond cutter having a tilt angle of 135 °. The light guide plate 20 thus formed has a step portion 21 inclined at 45 ° with respect to the bottom surface, and a flat portion 22 parallel to the bottom surface. The arrangement period of the step portions 21 is, for example, 120 μm. On the other hand, as the optical sheet 40a, a prism film BEF manufactured by Sumitomo Chemical Co., Ltd. was used. An adhesive 60 having a refractive index of 1.47 is attached to the flat surface of the optical sheet 40a on the back surface of the light guide plate 20.
And the mirror reflection at the interface was almost suppressed. The surface of the optical sheet 40a on which the microprisms 42 were formed was bonded to the glass surface of the panel using an adhesive having a refractive index of 1.56. With such a configuration, illumination free of interference fringes could be performed. The inclination angle of the uneven surface 41a of the microprism 42 is set so that the optical sheet 40a refracts the illumination light at an angle larger than the first-order diffraction of the illumination light by the light guide plate 20. The illumination light U is diffracted by the light guide plate 20. The first-order diffracted light at this time is represented by V. The diffraction angle is α. The first-order diffracted light V is refracted by the uneven surface 41a of the microprism 42. Refracted light is represented by W,
The angle of refraction is represented by β. The inclination angle of the uneven surface 41a is set so that the refraction angle β is larger than the diffraction angle α. Thereby, the coherence of the diffracted light can be almost eliminated.

[0025]

As described above, according to the present invention,
A light guide plate is provided on a reflective panel, and a light source for auxiliary illumination is provided at an end of the light guide plate. The light guide plate normally transmits external light to enter the panel and emits external light reflected from the panel, and, if necessary, guides illumination light to enter the panel and emits illumination light reflected from the panel as necessary. . In a dark environment, the light source is turned on so that an image can be observed even with a reflective panel. On the other hand, in a bright environment with abundant external light, the light source is turned off to save power. The light guide plate has a step portion divided into strips and a flat portion located between the step portions, and has a periodic structure. The light refraction layer having an uneven surface is interposed between the light guide plate and the panel, and the illumination light is refractively diffused. As a result, interference fringes (moire) caused by the periodic structure of the light guide plate can be suppressed, and the quality of the display screen can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic partial cross-sectional view showing an embodiment of a reflective display device according to the present invention, and shows a use state in a dark environment.

FIG. 2 is a schematic partial sectional view showing a use state in a bright environment.

FIG. 3 is a schematic cross-sectional view showing a reference example of a light guide plate used for a reflective display device.

FIG. 4 is a schematic diagram for explaining a method of using and a function of the light guide plate shown in FIG.

FIG. 5 is an explanatory diagram showing a cause of occurrence of moiré.

FIG. 6 is a schematic view showing an example of a light guide plate used in the present invention.

FIG. 7 is a functional explanatory view of the light guide plate shown in FIG.

FIG. 8 is a functional explanatory view of the light guide plate shown in FIG.

FIG. 9 is a cross-sectional view and a plan view showing an optical sheet used for a light refraction layer.

FIG. 10 is a schematic partial sectional view showing an embodiment of the present invention.

FIG. 11 is a schematic diagram showing an example of a conventional transmission type display device.

FIG. 12 is a schematic diagram illustrating an example of a conventional reflective display device.

[Explanation of symbols]

0 ... Panel, 1 ... First substrate, 2 ... Second substrate, 3 ... Guest host liquid crystal layer, 8 ... Light reflection layer,
9 ... quarter wave plate layer, 10 ... electrode, 11 ...
・ Electrode, 20 ・ ・ ・ Light guide plate, 21 ・ ・ ・ Step, 22 ・
..Planar part, 30 light source, 40 light refraction layer

Claims (5)

[Claims] 1. A transparent first substrate located on an incident side of external light, a second substrate joined to the first substrate via a predetermined gap and located on a reflection side, and electro-optic held in the gap. A panel provided with a substance and an electrode formed on at least one of the first and second substrates to apply a voltage to the electro-optical substance; a transparent light guide plate disposed outside the first substrate; A light source that is disposed at an end of the light guide plate and generates illumination light as needed. The light guide plate normally passes through external light, enters the first substrate, and reflects from the second substrate. While emitting external light, if necessary, illumination light is guided to be incident on the first substrate and the second
A reflection type display device that emits illumination light reflected from a substrate, wherein the light guide plate has a flat portion divided into strips and an inclined step portion located between the flat portions, and the light source The thickness of the illumination light decreases forward from the end where is located, and the illumination light guided forward is reflected by each of the steps to be incident on the first substrate and the illumination light reflected from the second substrate A light refraction layer having an uneven surface is interposed between the light guide plate and the first substrate to diffusely refract illumination light. 2. The reflection type display device according to claim 1, wherein the light refraction layer is made of an optical sheet in which micro prisms or micro lenses are arranged in a stripe shape. 3. The light refraction layer has an inclination angle of the uneven surface set so that the illumination light is refracted at an angle larger than first-order diffraction of the illumination light by the light guide plate. 2. The reflective display device according to 1. 4. The reflection type display device according to claim 1, wherein the panel uses a guest-host liquid crystal layer in which a dichroic dye serving as a guest is added to liquid crystal serving as a host as an electro-optical material. 5. The panel according to claim 1, further comprising: a light reflection layer located on the second substrate side and reflecting external light; and a quarter-wave plate layer interposed between the guest host liquid crystal layer and the light reflection layer. The reflective display device according to claim 4, further comprising: