JPH1195201A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to embody display images which are clear and high in contrast without the occurrence of clouding even if illumination is executed in the nighttime by removing the vibration component perpendicular to a substrate electrode surface from illumination light by a polarizing element. SOLUTION: If there is no polarizing element 107, the light of the vibration component in a C direction and the vibration component in a D direction is included in incident light 201. If the angle θformed by the incident light 201 and an A direction is small, the light of the Cx direction is small, but the light of the Cx direction component increases with an increase in θ. The refractive index of liquid crystal molecules with respect to the light of the Cx direction is different from the refractive index of a high-polymer matrix 114 and, therefore, the light is scattered at the boundary between liquid crystal molecule droplets 110 and the high-polymer matrix 114 and the clouding arises. If, however, the polarizing element 107 is disposed before the incidence of the illumination light of an illumination device is made incident on a display panel, the incident light 201 on a PDLC layer 103 turns to the D direction component and, therefore, the clouding does not occur as there is no light of the Cx direction component even if the angle θincreases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer-dispersed liquid crystal display.

[0002]

2. Description of the Related Art Projection display devices and paper-like monochrome reflection type display devices have been mainly used as display devices of polymer dispersed liquid crystal (hereinafter referred to as PDLC). P
DLC is obtained by dispersing liquid crystal molecules in a transparent polymer matrix. A PDLC layer having a thickness of about 10 μm is formed. When a voltage is applied in the thickness direction, the liquid crystal molecules are oriented in an electric field direction and the PDLC layer becomes transparent. .

On the other hand, when the liquid crystal molecules are not aligned, the liquid crystal becomes cloudy. A projection-type display device that applies the cloudy state and the transparent state as a shutter is a black and white reflective display that forms a display image with a white transparent background and a black transparent part with a black transparent background. It is.

As a third application of the PDLC, a see-through display device has been developed which positively utilizes the fact that the PDLC layer becomes transparent when a voltage is applied. FIG. 11 and FIG.
It is a conventional example of a see-through display using LC. When sufficient external light is obtained, such as in the daytime, the PDLC layer can obtain sufficient display luminance due to scattered external light. However, when sufficient external light cannot be obtained, such as at night, the display panel is illuminated using an illuminator as shown in FIGS. FIG.
In No. 1, the light from the light source (cold cathode tube) placed below and behind the PDLC panel was stopped down by a cylindrical lens, and the PDLC
Light the layers.

By disposing the light source below and behind the panel as shown in FIG. 11, the light source deviates from the field of view of the observer, and a see-through display can be realized.

In FIG. 12, a light guide plate is closely attached to the back of the PDLC panel, and a light source (cold cathode tube) is arranged at the lower end of the light guide plate. The light from the light source passes through the light guide plate and the PDLC panel,
Light is guided while repeating total reflection at the interface with air.

However, the light that has reached the cloudy part of the PDLC is scattered there and observed as a white display image by an observer. In FIG. 12, since the light source is completely invisible to the observer, a complete see-through display can be configured.

[0008]

In order to make the light source invisible to the observer, the light source is placed at a position far away from the line of sight of the observer watching the display, and the illumination light is applied to the PDLC layer therefrom. Must be irradiated.

Therefore, the illumination light enters the display panel at a shallow angle (the angle between the PDLC surface and the illumination light is small). Considering the transparent portion of the PDLC layer, since the liquid crystal molecules are oriented perpendicular to the display panel surface by the electric field, a large amount of illumination light on the vibration plane parallel to the optical axis of the liquid crystal molecules is incident on the transparent portion. PDLC is transparent because the refractive index of the liquid crystal molecules in the direction perpendicular to the optical axis matches the refractive index of the polymer matrix.

Conversely, since the refractive index of the liquid crystal molecules in the optical axis direction and the refractive index of the polymer matrix do not match, the illumination light on the vibrating surface parallel to the optical axis of the liquid crystal molecules is scattered by the PDLC layer. As a result, a thin cloudiness called haze appears in the transparent portion.

For the reasons described above, in a conventional see-through display with an illuminator using PDLC, haze generated in a transparent portion during nighttime illumination deteriorates the sense of clearness and lowers contrast. It was also a cause.

[0012]

In order to solve the above-mentioned problems, in the first display device, a vibration component perpendicular to the substrate electrode surface is removed from the illumination light applied to the display panel by using a polarizing element.

In the second display device, a polarizing element is provided at an incident portion of the light guide type illuminator for illuminating the display panel to the light guide plate, and light guide of a vibration component perpendicular to the light guide surface is removed.

In the third display device, a light absorbing layer is provided on an end face other than the incident portion in the light guide plate of the light guide type illuminator of the second display apparatus so as to absorb light reaching the end face.

In the fourth display device, an antireflection layer is provided on an end face of the light guide plate of the light guide type illuminator of the second display device, and the light reaching the end face is radiated out of the light guide plate.

In the fifth display device, in the light guide plate of the light guide type illuminator of the second display device, the spread of light in the direction parallel to the display surface of the display unit and perpendicular to the light guide direction is controlled at the entrance. The optical system was attached.

In the sixth display device, a louver film was attached as an optical element for controlling the light guide direction of the fifth display device so that the louver direction was perpendicular to the light guide plate surface.

In the seventh display, a prism sheet is attached as an optical element for controlling the light guide direction of the fifth display so that the ridge direction of the prism is perpendicular to the light guide plate surface.

In the eighth display device, a lenticular lens is attached as an optical element for controlling the light guide direction of the fifth display device so that the axial direction of the cylinder is perpendicular to the light guide plate surface.

In the ninth display, a Fresnel lens is attached as an optical element for controlling the light guide direction of the fifth display.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 1 shows the configuration of a display panel and an illuminator of a liquid crystal display according to Embodiment 1. FIG.
The display panel 100 shown in FIG. 1 includes two glass substrates 101 and a PDLC layer 103 interposed therebetween, and a transparent electrode 102 is provided on a surface of the glass substrate 101 facing the PDLC layer 103.

An AC power source 108 is connected to the transparent electrode 102.
Is connected. An illuminator 113 is provided below and below the display panel 100. This is to ensure the see-through property without a dazzling of the light source directly into the observer's field of view. At night, the display panel 100 is
To illuminate. The illuminator 113 includes the cold cathode tube 104 and the reflector 1
05. It comprises a cylindrical lens 106. The polarizing element 107 is placed on the front of the illuminator 113.

Next, the operation of the liquid crystal display according to the first embodiment will be described. When a voltage is applied to the transparent electrode 102 by the AC power supply 108, an electric field is applied to the PDLC layer 103 in the A direction. Since the transparent electrode 102 is patterned (not shown), the PDLC layer 103 has a portion to which an electric field is applied and a portion to which no electric field is applied. The liquid crystal molecules in the PDLC layer 103 are oriented in the direction A in the portion where the electric field is applied, and the direction of the liquid crystal molecules is at random in the portion where the electric field is not applied. When the display panel 100 is observed from the A direction, the liquid crystal molecules in the portion where the electric field is applied are oriented in the A direction. In this portion, the polymer around the liquid crystal molecule and the liquid crystal molecule have matching refractive indexes, so that the portion becomes transparent.

However, there are liquid crystal molecules that are not oriented in the direction A in the portion where no electric field is applied, and the polymer and liquid crystal molecules around the liquid crystal molecules do not have a matching refractive index. It becomes cloudy to scatter light. As described above, in the panel using PDLC, a display image is formed by a white image 112 in a transparent back 111, or a display image is formed by a transparent image in a white back.

A case where nighttime illumination is performed will be described with reference to FIG. FIG. 2 is a partially enlarged view of the PDLC layer 103, and shows a positional relationship between the display panel 100 and incident light 201 from an illuminator. The PDLC layer 103 has a structure in which liquid crystal molecule droplets 110 are dispersed in a transparent polymer matrix 114.

When a voltage is applied to the transparent electrode 102 by the AC power supply 108, an electric field is applied to the PDLC layer 103 in the A direction, and the optical axes of the liquid crystal molecules in the liquid crystal molecule droplet 110 are oriented in the A direction. The refractive index of the liquid crystal molecules with respect to the light on the vibration surface in the direction of the optical axis is different from the refractive index with respect to the light on the vibration surface in the direction perpendicular to the optical axis. Equal to the refractive index for

Considering the vibration plane of the incident light 201 on the PDLC layer 103, if the polarizing element 107 is not provided, the incident light 20
1 includes light of a vibration component in the C direction and light of a vibration component in the D direction (perpendicular to the paper surface). The vibration component in the C direction can be further decomposed into a Cx direction component and a Cy direction component. The Cx direction is the A direction, and the Cy direction is perpendicular to the A direction. As can be seen from FIG. 2, assuming that the angle between the incident light 201 and the direction A is θ, when θ is small, the Cx direction component is also small, but as θ increases, the light in the Cx direction component increases. Since the refractive index of the liquid crystal molecules with respect to the light in the Cx direction is different from the refractive index of the polymer matrix 114, the liquid crystal molecules are scattered at the interface between the liquid crystal molecule droplet 110 and the polymer matrix 114 to cause white turbidity.

Here, considering the layout of the illuminator in the see-through display in FIG. 1, in order to prevent the illuminating light from directly entering the field of view of the observer of the display panel 100, the incident light from the illuminator 113 must be The angle in the direction A must be increased. That is, θ in FIG. 2 increases, and the light in the Cx direction component increases.

However, if the polarizing element 107 having the polarization direction 109 is provided before the illumination light from the illuminator 113 shown in FIG. 1 is incident on the display panel 100, the PDLC layer 10 shown in FIG.
Since the incident light 201 to 3 becomes a component in the D direction, even if the angle θ becomes large, there is no light in the Cx direction, so that white turbidity does not occur. That is, it is possible to realize a see-through display device that does not cause cloudiness due to nighttime illumination.

(Embodiment 2) FIG. 3 shows a configuration of a display panel and an illuminator of a liquid crystal display according to Embodiment 2. The display panel 100 has the same structure as that of FIG. 1, and an AC power supply 108 is connected to the transparent electrode 102. The illuminator of FIG. 3 is a light guide type, in which a transparent light guide plate 301 is attached to the back of the display panel 100, and a polarizing element 307 whose polarization direction is perpendicular to the A direction is attached to the lower end surface of the light guide plate 301. A cold cathode tube 104 as a light source and a reflection plate 305 are attached below. By using such a light guide type illuminator, the light source can be completely invisible to an observer, and the display panel 100 and the illuminator can be integrated, so that a compact see-through display can be realized.

Next, the operation of the liquid crystal display according to the second embodiment will be described. The mechanism by which the PDLC layer 103 of the display panel 100 becomes transparent is exactly the same as that described in the first embodiment.

Here, only the illumination system will be described. Since the light 302 emitted from the cold cathode tube 104 is non-polarized,
Light of a direction component and light of a D direction component perpendicular to the A direction are also included. The component in the C direction includes a vibration component in a direction A perpendicular to the display panel surface. The light 302 exiting the cold cathode tube 104 passes through the polarizing element 307 and becomes polarized light 303 having only a component in the D direction, and becomes a light guide plate 301 and the PDLC layer 10 of the display panel 100.
The light is guided through the transparent area 3 while repeating reflection. The relationship between the PDLC layer 103 and the light guide 303 incident on the PDLC layer 103 at this time will be considered with reference to FIG. Here, the light guide 303 corresponds to the incident light 201.

At this time, since the light guide 303 is guided through the relatively thin thickness of the light guide plate 301 and the display panel 100, the angle θ between the direction A and the incident light 201 increases. However, as shown in FIG. 3, when the light is incident on the light guide plate 301, the light in the C-direction component causing the white turbidity is removed by the polarizing plate 307. For this reason, the light guide 303 has a small amount of light in the C-direction component, so that white turbidity due to illumination light can be significantly reduced, and a see-through display that is more compact than the structure shown in FIG.

(Embodiment 3) FIG. 4 shows a configuration of a display panel and an illuminator of a liquid crystal display according to Embodiment 3. The display device shown in FIG. 4 is a see-through liquid crystal display device provided with a light guide type illuminator, similarly to the second embodiment.
The display panel 100 has exactly the same configuration as that of the second embodiment. A light guide plate 301 is provided on the back surface of the display panel 100, and a polarizing element 303, a cold cathode tube 104 and a reflector 305 are provided on the lower end surface of the light guide plate 301. Are attached in the same manner as in the second embodiment. However, unlike the second embodiment, the light absorbing layer 401 is provided on an end surface of the light guide plate 301 other than the lower end surface where the polarizing element 307 is attached.

Next, the operation of the third embodiment will be described. In the third embodiment, the operations of the display panel 100, the polarizing element 303, and the cold cathode tubes 104 are exactly the same as those in the second embodiment. However, the movement of the illumination light from the cold cathode tube 104 will be described more precisely here. As described in the second embodiment, the illumination light is guided through the light guide plate 301 and the transparent region of the PDLC layer 103 of the display panel 100. Since the total thickness of the light guide plate 301 and the display panel 100 is considerably smaller than the area of the back surface of the light guide plate 301 and the display surface of the display panel 100, most of the illumination light from the cold cathode tubes 104 The light is reflected and guided only on a plane including the polarization axis of the polarizing element 307, such as the front and back surfaces of the display device 301 and the display surface of the display panel 100.

In this case, since the direction of polarization of the guided light is preserved in the direction of polarization by the polarizing plate 307, the angle θ in FIG.
No cloudiness occurs regardless of the size of the. However, since the light generated by the cold-cathode tube 104 is considered to be scattered light from the surface of the cold-cathode tube, the light that enters the light guide plate 301 like the incident light 403 and then reaches the lateral end surface 404 of the light guide plate 301. Exists.

If the incident light 403 is reflected by the lateral side surface 404, the polarization direction E at the time of incidence becomes the F direction after reflection, the polarization direction is not preserved, and there is a possibility that white turbidity may occur. This opacity is a level that does not cause any problem during normal nighttime, but special conditions such as when the display is placed in complete darkness or when the light source uses a high-intensity light source different from a normal cold-cathode tube Then it becomes a real problem.

This situation will be described with reference to FIG. The incident light 501 in FIG. 5 corresponds to the incident light 403 in FIG. 4, the reflection surface 503 corresponds to the lateral end surface 404, the polarization direction 505 corresponds to the E direction, and the polarization direction 506 after reflection corresponds to the F direction. The YZ plane is the direction of the display surface of the display panel 100, and 504 is the plane of incidence of the incident light 501 on the reflection plane 503.

The polarization direction 505 of the incident light 501 and the incident surface 5
04 is not 0 or 90 degrees, the incident light 50
One vibration component is decomposed into a P-wave component parallel to the incident surface and S perpendicular to the incident surface. Generally, since the reflectance of the P-wave component and the reflectance of the S-wave component are different, the polarization direction 506 of the reflected light 502 is
It rotates with respect to the polarization direction 505 of 01. Returning to FIG. 4, the angle between the plane of incidence of the obliquely incident light 403 on the lateral end surface 404 and the polarization direction E is generally 90 degrees even at 0 degrees.
If the incident light 403 is reflected by the lateral end surface 404, the polarization direction changes and white turbidity occurs.

However, since the light-absorbing layer is provided on the portions other than the lower end surface of the light guide plate 301, the light reaching the lateral end surface is absorbed without being reflected, so that white turbidity does not occur. By providing the light absorbing layer on the end face of the light guide plate 301, the display may be placed in complete darkness, or a special light source such as a high-intensity light source different from a normal cold cathode tube may be used. Under these conditions, a see-through liquid crystal display that does not cause cloudiness can be realized.

(Embodiment 4) Similarly, Embodiment 4 will be described with reference to FIG. In the third embodiment, the incident light 403
When the photoconductor reached the lateral end face 404, a light absorbing layer 401 was provided to eliminate reflection. However, if the reflected light is eliminated, the discussion of the third embodiment holds as it is. In the fourth embodiment, reflected light can be eliminated by providing a non-reflective layer 402 instead of the light absorbing layer 401, and when the display is placed in complete darkness, or when the light source is a normal cold cathode. Even under special conditions such as using a high-intensity light source different from a tube, a see-through liquid crystal display that does not cause white turbidity can be realized.

(Embodiment 5) FIG. 6 shows a configuration of a display panel and an illuminator of a liquid crystal display according to Embodiment 5. The display device shown in FIG. 6 is a see-through liquid crystal display device provided with a light guide type illuminator, similarly to the second embodiment.
The display panel 100 has exactly the same configuration as that of the second embodiment. A light guide plate 301 is provided on the back surface of the display panel 100, and a polarizing element 303, a cold cathode tube 104 and a reflector 305 are provided on the lower end surface of the light guide plate 301. Are attached in the same manner as in the second embodiment. The difference from the second embodiment is that the polarizing element 3
The point is that the diffusion suppressing optical element 601 is provided between the cold cathode fluorescent lamp 103 and the cold cathode tube 104.

Next, the operation of the fifth embodiment will be described. As described in the third embodiment, the illumination light from the cold-cathode tube 104 is scattered light, and when the incident light obliquely incident on the light guide plate 301 is reflected on the lateral end face, the polarization direction is rotated. Cloudiness occurs.

As described above, the light emitted from the point P on the surface of the cold cathode tube 104 is considered. Since the light emitted from the cold-cathode tube is scattered light, it also spreads in the direction perpendicular to the direction A. Therefore,
The light spreading in the direction perpendicular to the direction A is transmitted to the diffusion suppressing optical element 6.
When the spread of the incident light 602 is suppressed by 01, the incident light reaching the lateral end surface 404 of the light guide plate 301 can be greatly reduced. The characteristics of the diffusion suppressing optical element 601 will be described. First, the characteristics as viewed from the direction (A) are shown in FIG. The light emitted from the point P on the cold cathode tube 104 to the left and right is controlled almost in parallel to the light guide direction by the diffusion suppressing optical element 601, and enters the lower end surface of the light guide plate 301 via the polarizing element 303.

On the other hand, FIG. 6- (A) shows the characteristics when viewed from the direction (A). The characteristics shown in FIG. 6A are characteristics in the thickness direction of the display device. As can be seen from the figure, the diffusion suppressing optical element 601 does not control light in the thickness direction of the display. This is because the light that spreads in the thickness direction reaches a plane parallel to the display surface, and does not cause cloudiness because the polarization direction of the light guide does not rotate.

As described above, by providing the diffusion suppressing optical element 601 for suppressing the spread of light in the horizontal direction on the display surface between the polarizing element 303 and the cold cathode tube 104, the light reflected on the lateral end face of the light guide plate is eliminated. A see-through liquid crystal display that does not produce white turbidity even when the display is placed in complete darkness or under special conditions such as using a high-intensity light source different from a normal cold-cathode tube. realizable.

(Embodiment 6) FIG. 7 shows a configuration of a light guide type illuminator of a liquid crystal display according to Embodiment 6. The configuration of the illuminator is the same as that of the fifth embodiment.
A polarizing element 303 is provided on the lower end surface of the device 1, and a cold cathode tube 104 and a reflector (not shown) are provided below the polarizing element 303. A louver film 701 is provided between the polarizing element 303 and the cold cathode tube 104. The louver film is an optical element having a structure in which light absorbing microlouvers 702 are arranged at equal intervals in a transparent resin 703. And the louver film 70
The mounting of 1 is performed so that the microlouver 702 is in the thickness direction of the display.

Next, the operation of the sixth embodiment will be described. Scattered light (incident light) 704 having a spread in the Y direction is emitted from the cold cathode tube 104. When this incident light enters the louver film 701, the micro louver 70
Light 705 substantially parallel to 2 passes through the louver film 701 through the transparent resin 703, is polarized in the Y direction by the polarizing element 303, and then enters the light guide plate 301 as incident light 706. However, light incident on the louver film 701 obliquely in the Y direction is absorbed by the microlouver 702 and does not pass through the hoover film 701.

Therefore, the polarization incident on the light guide plate 301 is Y
Since the spread in the direction is very small, the amount of light reflected on the lateral end surface 404 of the light guide plate 301 is very small, and white turbidity due to rotation of the polarization direction does not occur. Therefore, it is possible to realize a see-through liquid crystal display that does not cause white turbidity even when the display is placed in complete darkness or under special conditions such as using a high-luminance light source different from a normal cold-cathode tube.

(Embodiment 7) FIG. 8A shows a configuration of a light guide type illuminator of a liquid crystal display in Embodiment 7. The configuration of the illuminator is the same as that of the fifth embodiment. A polarizing element 303 is provided on the lower end surface of the light guide plate 301, and a cold cathode tube 104 and a reflector (not shown) are provided below the polarizer. Also,
There is a prism sheet 801 between the polarizing element 303 and the cold cathode tube 104. The prism sheet is an optical element having a structure in which irregularities on a triangular prism are formed in a stripe shape at equal intervals on one surface of a transparent resin sheet. Prism sheet 80
The mounting of 1 is performed so that the ridge line 802 of the prism is in the thickness direction of the display.

Next, the operation of the seventh embodiment will be described. Scattered light 704 having a spread in the Y direction is emitted from the cold cathode tube 104. When the scattered light 704 enters the prism sheet 801, transmitted light 805 having a small spread in the Y direction is emitted from the prism surface of the prism sheet 801, is polarized in the Y direction by the polarizing element 303, and then enters the light guide plate 301. Light 806 is incident. This is shown in FIG. Incident light 704 is incident on the lower surface of the prism sheet 801 in various directions.

However, from the prism surface, ψ
Only the light 805 having the spread of the light is emitted. Light 807 in the other direction is reflected on the prism surface as shown in the figure, and is emitted from the lower surface of the prism sheet 801. The spread angle ψ of the light emitted from the prism surface can be set by the vertex angle of the prism.

As described above, by reducing the spread of the polarized light incident on the light guide plate 301 in the Y direction by the prism sheet, the reflected light on the lateral end surface 404 of the light guide plate 301 can be reduced. As a result, generation of cloudiness due to rotation of the polarization direction can be suppressed.

Therefore, a see-through liquid crystal display which does not cause white turbidity even when the display is placed in complete darkness or under special conditions such as using a high-luminance light source different from a normal cold-cathode tube is used. realizable.

(Eighth Embodiment) FIG. 9A shows a configuration of a light guide type illuminator of a liquid crystal display according to an eighth embodiment. The configuration of the illuminator is the same as that of the fifth embodiment. A polarizing element 303 is provided on the lower end surface of the light guide plate 301, and a cold cathode tube 104 and a reflector (not shown) are provided below the polarizer. Also,
There is a lenticular lens 901 between the polarizing element 303 and the cold cathode tube 104. The lenticular lens has a structure in which semi-cylindrical irregularities are formed on one surface of a transparent resin sheet, and a large number of cylindrical lenses are arranged at equal intervals. The lenticular lens 901 is attached so that the axial direction of the cylindrical lens is in the thickness direction of the display.

Next, the operation of the eighth embodiment will be described. Scattered light (incident light) 704 having a spread in the Y direction is emitted from the cold cathode tube 104. When the incident light 704 is incident on the lenticular lens 901, transmitted light 905 having a small spread in the Y direction is emitted from the lens surface of the lenticular lens 901, and is polarized by the polarizing element 303 in the Y direction. Light is incident as incident light 906.

FIG. 9A shows this state. Since the lenticular lens 901 has a convex lens shape in the Y direction, if the cold cathode tubes 104 are arranged at the focal positions of the individual cylindrical lenses, parallel light can be extracted from the lenticular lens 901 in the Y direction in principle. Although it is actually difficult to realize perfect parallel light, transmitted light 905 having a very small spread in the Y direction with respect to incident light in various directions.
Can be obtained.

On the other hand, since the lenticular lens has no light condensing ability in the thickness direction of the display, the incident light 704 is radiated as it is as it is.

As described above, by reducing the spread of the polarized light incident on the light guide plate 301 in the Y direction by the lenticular lens, the reflected light on the lateral end surface 404 of the light guide plate 301 can be reduced. As a result, generation of cloudiness due to rotation of the polarization direction can be suppressed. Therefore, it is possible to realize a see-through liquid crystal display that does not cause white turbidity even when the display is placed in complete darkness or under special conditions such as using a high-luminance light source different from a normal cold-cathode tube.

Ninth Embodiment FIG. 10 shows the configuration of a light guide type illuminator of a liquid crystal display according to a ninth embodiment. The configuration of the illuminator is the same as that of the fifth embodiment.
A polarizing element 303 is provided on the lower end surface of the device 1, and a cold cathode tube 104 and a reflector (not shown) are provided below the polarizing element 303. Here, the lower end surface of the light guide plate 301 is inclined toward the display panel by an angle α. A Fresnel lens 1001 is provided between the polarizing element 303 and the cold cathode tube 104.

Next, the operation of the ninth embodiment will be described. Scattered light (incident light) 704 having a spread in the Y direction is emitted from the cold cathode tube 104. When the incident light 704 enters the Fresnel lens 1001, transmitted light 1005 having a small spread in the X direction and the Y direction is emitted from the lens surface of the Fresnel lens 1001.
After being polarized in the direction, the light enters the light guide plate 301 as incident light 1006.

The Fresnel lens 1001 used here is X
Since the cold cathode tube 104 is arranged at the focal point of each convex lens, parallel light can be extracted from the Fresnel lens 1001 in principle because both the direction and the Y direction are convex lens shapes. Although it is difficult to realize perfect parallel light in reality, the radiation light 1 having a very small spread with respect to incident light in various directions.
005 can be obtained. This Fresnel lens 100
1 also has a light condensing ability also in the X direction.

Therefore, the display surface can be uniformly illuminated by tilting the Fresnel lens 1001 in the direction of the mounting surface 1002 of the display panel. Conversely, the illuminance distribution in the Z direction can be changed by adjusting the tilt angle α.

As described above, the spread of the polarized light incident on the light guide plate 301 is reduced by the Fresnel lens, and the lens is inclined in the direction of the display surface, so that the light reflected on the lateral end surface 404 of the light guide plate 301 can be reduced. As a result, generation of cloudiness due to rotation of the polarization direction can be suppressed.

Therefore, a see-through liquid crystal display that does not cause white turbidity even when the display is placed in complete darkness or under special conditions such as using a high-luminance light source different from a normal cold-cathode tube is used. realizable.

[0066]

As described above, according to the present invention, P
Even when the see-through liquid crystal display panel using DLC is illuminated, there is a remarkable effect that a clear and high-contrast display image can be realized without causing white turbidity.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view of a liquid crystal display according to Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram of a cause of occurrence of white turbidity and a solution principle.

FIG. 3 is an explanatory diagram of a configuration of a liquid crystal display according to Embodiment 2 of the present invention.

FIG. 4 is a configuration explanatory view of a liquid crystal display according to Embodiment 3 of the present invention.

FIG. 5 is an explanatory view of the principle of white turbidity countermeasures according to a fourth embodiment of the present invention.

FIG. 6 is a configuration explanatory view of a liquid crystal display according to a fifth embodiment of the present invention.

FIG. 7 is a structural explanatory view of a liquid crystal display according to a sixth embodiment of the present invention.

FIG. 8 is a structural explanatory view of a liquid crystal display according to a seventh embodiment of the present invention.

FIG. 9 is a diagram illustrating a configuration of a liquid crystal display according to an eighth embodiment of the present invention.

FIG. 10 is a configuration explanatory view of a liquid crystal display according to a ninth embodiment of the present invention.

FIG. 11 is a diagram showing a first configuration example of a liquid crystal display in a conventional example.

FIG. 12 is a diagram showing a second configuration example of a liquid crystal display in a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Display panel 101 Glass substrate 102 Transparent electrode 103 PDLC layer 104 Cold cathode tube 105 Reflector 106 Cylindrical lens 107 Polarization element 108 AC power supply 109 Polarization direction of polarization element 110 Liquid crystal droplet 111 Transparent part 112 Cloudy part 113 Illuminator 114 Polymer Matrix 201 Incident light 301 Light guide plate 302 Incident light from cold-cathode tube 303 Incident light to light guide plate 305 Reflector 307 Polarizing element 401 Light absorption layer 402 Anti-reflection layer 403 Incident light to light guide plate in oblique direction 404 Horizontal end face 501 Incident light 502 Reflected light 503 Reflective surface 504 Incident surface 505 Polarized direction of incident light 506 Polarized direction of reflected light 601 Diffusion suppressing optical element 602 Light incident on light guide plate 603 Light incident on light guide plate 701 Louver film 702 Microlouver 703 Transparent resin 704 Incident light from a cold cathode tube 705 Transmitted light from a louver film 706 Incident light to a light guide plate 801 Prism sheet 802 Prism ridgeline 805 Transmitted light from a prism sheet 806 Incident light to a light guide plate 807 Inside prism sheet 901 Lenticular lens 905 Transmitted light from lenticular lens 906 Light incident on light guide plate 1001 Fresnel lens 1002 Display panel mounting surface 1005 Transmitted light from Fresnel lens 1006 Incident light on light guide plate

Claims (9)

[Claims] 1. A liquid crystal display comprising: a liquid crystal display having a structure in which a polymer dispersed liquid crystal is sandwiched between two substrates having electrodes on one side; and an illuminator for illuminating the display. A liquid crystal display device comprising: a polarizing element that removes illumination light on a vibration plane perpendicular to an electrode surface on the substrate on an optical path of illumination light from the device to the display. 2. A light guide comprising: a liquid crystal display having a structure in which a polymer dispersed liquid crystal is sandwiched between two substrates having electrodes on one side; and a light source disposed at an end of a light guide plate adjacent to the display. A liquid crystal display device having a illuminator of a system, characterized in that a polarizing filter having a polarization axis parallel to a surface of the light guide plate facing the display portion is provided at an entrance of the light of the light source to the light guide plate. Liquid crystal display. 3. A liquid crystal display having a light guide type illuminator, wherein a light absorbing layer is provided on an end surface of the light guide plate of the illuminator other than the illumination light entrance. Liquid crystal display device. 4. The liquid crystal display device according to claim 2, wherein the liquid crystal display device has a light guide type illuminator, and further comprises an anti-reflection layer on an end face of the light guide plate of the illuminator. 5. A liquid crystal display having a light guide type illuminator, wherein an optical system for suppressing spread of light in a direction perpendicular to the light guide direction in the light guide plate is provided as an entrance of illumination light to the light guide plate. The liquid crystal display device according to claim 2, wherein the liquid crystal display device is provided in a unit. 6. A liquid crystal display having a light guide type illuminator, wherein a louver film is attached to an entrance of illumination light to a light guide plate such that a direction of a louver is perpendicular to a display surface of a display unit. 3. The liquid crystal display device according to claim 2, wherein: 7. A liquid crystal display having a light guide type illuminator, wherein a prism sheet is attached to an entrance of illumination light to a light guide plate such that a ridge direction of the prism is perpendicular to a display surface of a display unit. 3. The liquid crystal display device according to claim 2, wherein: 8. A liquid crystal display having a light guide type illuminator, wherein a lenticular lens is attached to an entrance of illumination light to a light guide plate such that an axial direction of a cylinder is perpendicular to a display surface of a display unit. 3. The liquid crystal display device according to claim 2, wherein: 9. The liquid crystal display according to claim 2, wherein a condensing Fresnel lens is attached to an entrance of illumination light to the light guide plate in a liquid crystal display having a light guide type illuminator. Display device.