JP2003007114A - Front light and reflection type display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance visibility of a display surface by making a optimized design of a prism shape of a light guide plate easy with fixed polarization of incident light into the light guide plate, with achieving low power consumption by enhancing an efficiency of utilization of light from a light source through recombination of polarization and reflection. SOLUTION: This front light has a point light source 51, a guide rod 62 that converts light from the point light source to a uniform linear light source and a transmissive light guide plate 12 that has unevenness on one surface, and the front light outputs lighting light through the other surface of the light guide plate 12. A prism sheet 64 that reduces light to parallel light and a reflection-polarization film 65 that gives fixed polarization are located between the guide rod 62 and the light guide plate 12. Furthermore, a scattering reflector 66 that encloses the periphery of the guide rod 62 is arranged and reflectors 16 is arranged on three side surfaces other than the side surface opposite the light source of the light guide plate 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front light for supplementarily irradiating a reflection type display panel for displaying by utilizing external light such as natural light when the external light is scarce. The present invention relates to a reflective display device using.

[0002]

2. Description of the Related Art A flat panel type display device typified by a liquid crystal display device includes a transmissive display device for displaying by transmitting light incident on the display panel and a light transmission type display device for reflecting light incident on the display panel. It is roughly classified into a reflection type display device for displaying.

A transmissive liquid crystal display device, which is a typical transmissive display device, has a liquid crystal display element in which a liquid crystal layer is held between two glass substrates provided with transparent electrodes. Liquid crystal display panels are configured by arranging polarizing plates on both sides of. In this transmissive liquid crystal display device, the liquid crystal display panel is irradiated with light by an illuminating device arranged on the back surface of the liquid crystal display panel, and linearly polarized light is incident on the liquid crystal layer through the polarizing plate. Then, by applying a voltage between the transparent electrodes provided on the two glass substrates, the polarization state of the linearly polarized light incident on the liquid crystal layer is modulated, and a display image is formed by the light transmitted through the liquid crystal layer. .

The backlight as the illuminating device is an indispensable constituent element of the transmissive liquid crystal display device, and must be constantly turned on during display. Therefore, there is a problem that a large amount of power is consumed by the backlight with respect to the power consumption of the entire display device. In such a transmissive liquid crystal display device, various methods have been developed to improve brightness and reduce power consumption. But,
Since the backlight consumes most of the electric power of the entire display device, the transmissive liquid crystal display device is not suitable as a display device for a mobile device which needs to be driven by a battery for a long time.

On the other hand, a reflection type liquid crystal display device, which is a typical reflection type display device, has a reflection plate arranged on the back surface of a liquid crystal display element and a polarizing plate and a retardation plate on the front surface (display surface) side. A liquid crystal display panel is configured. In this reflective liquid crystal display device, external light such as natural light enters the liquid crystal display panel from the front surface (display surface) side of the liquid crystal display panel. Then, by applying a voltage between the transparent electrodes provided on each of the two glass substrates, the polarization state of the linearly polarized light incident on the liquid crystal layer of the liquid crystal display element is modulated, and the linearly polarized light is transmitted through the liquid crystal layer and reflected by the reflection plate. A display image is formed by the light reflected at.

Since the reflective liquid crystal display device does not use a backlight for irradiating light from the back surface of the liquid crystal display panel, power consumption can be reduced as compared with the transmissive liquid crystal display device. Therefore, the reflective liquid crystal display device is suitable as a display device for mobile devices, and in recent years, various types of reflective display devices have been developed.

The reflective display device has the advantages as described above as compared with the transmissive display device, but it may not be easy to observe a display image in an environment where external light is scarce. In order to solve such a problem, a reflective display device using a front light, which is a planar lighting device, has been developed. The front light used in this reflection type display device includes a light guide plate (planar light guide) having a light transmitting property on the front surface of the reflection type display panel and a light source arranged near the periphery of the light guide plate. The light emitted from the light source enters the light guide plate, and the light is emitted from the surface of the light guide plate to the reflective display panel.

In the reflection type display device provided with the front light which is such a planar illumination device, the illumination light is emitted to the display panel by turning on the front light even in the environment where the external light is scarce. The displayed image can be easily viewed. Further, in an environment in which sufficient external light exists, the display image can be visually recognized through the light guide plate without turning on the light source, so that power consumption can be reduced.

[0009]

In the above-mentioned transmission type liquid crystal display device, the light emitted from the backlight arranged on the back surface of the liquid crystal display panel is reflected by the polarizing plate arranged on the light incident side of the liquid crystal display element. There is a problem that more than half is absorbed. Therefore, in the transmissive liquid crystal display device, it is necessary to increase the illuminance of the backlight in order to improve the display brightness. In order to increase the illuminance of the back light, a large amount of electric power is required, and there is a problem that power consumption increases.

On the other hand, in the reflection type liquid crystal display device, it is not necessary to turn on the front light in an environment in which a sufficient amount of outside light exists, so that the power consumption can be sufficiently reduced. Furthermore, in an environment where external light is scarce, the display panel is illuminated with light by turning on the light source of the front light, so that the display image can be easily viewed. However, even in the reflective liquid crystal display device, the emitted light from the front light is absorbed by more than half by the polarizing plate arranged on the light incident side of the liquid crystal display element, and therefore, like the backlight in the transmissive liquid crystal display device. However, there is a problem that the utilization efficiency of light is low. Therefore, also in the reflective liquid crystal display device, in order to improve the display brightness, it is necessary to increase the illuminance of the front light, which requires a large amount of electric power. Therefore, also in the reflective liquid crystal display device, it is required to reduce the power consumption of the front light.

In a transmissive liquid crystal display device, in order to solve the problem that the backlight consumes a large amount of power as described above, for example, in Japanese Patent Laid-Open No. 9-258221, illumination light from a light source is used as a polarization plane. Are separated into two linearly polarized light directions that are orthogonal to each other, one linearly polarized light is rotated by 90 ° to match the other polarized light plane, and then the polarized light is provided with a means for merging both lights having the same polarized light planes. A configuration using a backlight is disclosed. With such a configuration, the illumination light has its polarization plane aligned with that of the polarizing plate arranged on the light incident side of the liquid crystal display element, so that light loss corresponding to one polarizing plate does not occur and the light utilization efficiency is improved. .

Further, in Japanese Unexamined Patent Application Publication No. 10-253830, a polarization separation / recombination film is provided on the light emitting surface side of the planar light guide, and this film allows the illumination light from the light source to have a polarization plane with respect to each other. Polarization backlight that splits into orthogonal linearly polarized light or splits the illumination light from the light source into right-handed circularly polarized light and left-handed circularly polarized light, and reflects one polarized light by a reflector to match the other polarized light. Is disclosed. With such a configuration, the illumination light has its polarization plane aligned with that of the polarizing plate arranged on the light incident side of the liquid crystal display element, so that light loss corresponding to one polarizing plate does not occur and the light utilization efficiency is improved. .

However, the above-mentioned Japanese Patent Laid-Open No. 9-2582.
In the configuration disclosed in Japanese Patent Publication No. 21, although the utilization efficiency of the light emitted from the back light is improved, a means for separating the light into a linear polarization direction, a means for polarizing the polarization direction, and a means for combining the light with the backlight. Therefore, there is a problem that the size of the display device becomes large.

Further, it is conceivable to apply the backlight disclosed in Japanese Patent Laid-Open No. 10-253830 as a front light of a reflective liquid crystal display device. In this case, a display image is displayed via a light guide plate. Since it is visible, the polarization separation / recombination film must be provided on the light exit surface side of the light guide body, which may deteriorate the visibility of the displayed image.

Further, in Japanese Patent Laid-Open No. 11-218757, a prism-shaped unevenness is provided on the display surface side of a light guide in a front light, and total reflection of light at the sloped surface of the unevenness is utilized to remove light from a light source. A configuration is disclosed in which the light incident on the light guide body is irradiated to the display panel side.

However, in this structure, there is a risk that light leaks to the display surface side depending on the angle of the incident light entering the sloped surface of the unevenness and the prism shape, and the light leaks to the display surface side. Therefore, there is a problem in that the visibility of the display image is deteriorated. Further, when the user observes the display light of the reflective liquid crystal display device, the specularly reflected light from the front light overlaps with each other, which causes a problem that the contrast of the display image deteriorates.

The present invention has been made to solve the problems of the prior art as described above, and it is possible to reduce the power consumption by improving the utilization efficiency of the light from the light source.
An object of the present invention is to provide a front light in which the visibility of a display image is improved and a reflective display device using the same.

[0018]

In order to solve the above-mentioned problems, a front light according to the first aspect of the present invention is arranged so that a light source and light emitted from the light source enter one side surface thereof. One surface is flat, and the other surface has a gentle slope portion that totally reflects the light totally reflected by the flat surface and a steep slope portion that specularly emits the light from the other surface. It has a light guide plate formed in a concave and convex shape and a polarization means for making light incident on the light guide plate from the light source into a predetermined polarization state.

According to the above configuration, the first embodiment described later
As shown in FIG. 5, the light emitted from the light source can be made to enter the light guide plate in a predetermined polarization state by the polarization means provided between the light guide plate and the light source. Optimized prismatic uneven shape provided on the side (display surface side) where external light of the light guide plate is incident compared to when general light source light whose polarization state is not constant is incident on the light guide plate To facilitate the design. That is, in this case, since it is necessary to consider only the case where the incident light has a specific polarization state, the design becomes easy, and the optimization design is performed to determine the angle of the incident light to the inclined surface portion of the light guide plate and the prism. It is possible to reduce the light leaked to the display surface side depending on the shape. As a result, it is possible to prevent the visibility of the display image from being deteriorated due to the leaked light. Further, in the light guide plate, the incident light travels while maintaining the polarization plane, so that a predetermined polarized light can be emitted from the light guide plate. Therefore, by matching the polarization plane of the polarizing plate provided on the light incident side of the reflective display panel with the polarization axis of a predetermined polarized light, almost all of the predetermined polarized light is used for display, and the light utilization efficiency is improved. Can be improved.

By using, as the polarization means, a polarization means for converting the light incident on the light guide plate from the light source into linearly polarized light, the linearly polarized light can be made incident on the light guide plate.

The front light according to the second aspect of the present invention comprises a point light source, a guide rod for converting the light incident from the point light source into uniform linear light and making it enter the light guide plate, and a guide rod from the guide rod. Arranged so that light enters from one side surface, one surface is flat and the other surface is a gentle slope and a regular reflection that totally reflects the light that is totally reflected by the flat surface. And a light guide plate formed in a concavo-convex shape having a steep surface portion to be emitted from the other surface, and a polarization means for making light incident on the light guide plate from the guide rod into a predetermined polarization state.

According to the above configuration, a second embodiment described later
As shown in, the light emitted from the point light source can be made uniform like the light from the linear light source and incident on the light guide plate by the guide rod. Furthermore, the polarization means provided between the light guide plate and the guide rod allows the light incident from the point light source via the guide rod to enter the light guide plate in a predetermined polarization state. Compared to the case where general light source light whose polarization state is not constant is incident on the light guide plate, the prism-shaped concavo-convex shape formed on the side of the light guide plate on which the external light is incident (display surface side) is optimal. It is possible to reduce the amount of light leaked to the display surface side depending on the angle of light incident on the inclined surface portion of the light guide plate and the prism shape by performing an optimized design. As a result, it is possible to prevent the visibility of the display image from being deteriorated due to the leaked light. Further, in the light guide plate, the incident light travels while maintaining the polarization plane, so that a predetermined polarized light can be emitted from the light guide plate. Therefore, by matching the polarization plane of the polarizing plate provided on the light incident side of the reflective display panel with the optical axis of a predetermined polarized light, most of the predetermined polarized light is used for display and the light utilization efficiency is improved. Can be made.

The front light according to the third aspect of the present invention comprises a point light source, a guide rod for converting the light incident from the point light source into uniform linear light and making it enter the light guide plate, and a guide rod from the guide rod. It is arranged so that light is incident from one side surface to the inside, and one surface is flat and the other surface is a gentle slope portion that totally reflects the light totally reflected by the flat surface. The light guide plate is formed in an uneven shape having a steeply inclined surface portion that is specularly reflected and emitted from the other surface, and a polarization unit that makes the light incident on the guide rod from the point light source into a predetermined polarization state. .

According to the above configuration, the third embodiment described later
As shown in FIG. 3, the guide rod can make the light emitted from the point light source uniform like a linear light source and enter the light guide plate. Furthermore, the polarization means provided between the point light source and the guide rod allows the light incident from the point light source through the guide rod to enter the light guide plate in a predetermined polarization state. Compared to the case where general light source light whose polarization state is not constant is incident on the light guide plate, the prism-shaped concavo-convex shape formed on the side of the light guide plate on which the external light is incident (display surface side) is optimal. Design is easy,
By optimizing the design, it is possible to reduce the light leaked to the display surface side depending on the angle of the light incident on the inclined surface portion of the light guide plate and the prism shape. As a result, it is possible to prevent the visibility of the display image from being deteriorated due to the leaked light. Further, in the light guide plate, the incident light travels while maintaining the polarization plane, so that a predetermined polarized light can be emitted from the light guide plate. Therefore, by matching the polarization plane of the polarizing plate provided on the light incident side of the reflective display panel with the optical axis of a predetermined polarized light, most of the predetermined polarized light is used for display and the light utilization efficiency is improved. Can be made. Further, as the polarizing means for obtaining the predetermined polarized light, other than a plate-like or film-like one such as a beam splitter can be used.

As the polarizing means, a reflection type polarizing plate which transmits a predetermined linearly polarized light and reflects other light can be used. Further, the reflection light reflected by the reflection type polarizing plate is random light or 90 By providing the polarization converting means for converting the light into the polarized light, the reflected light reflected by the reflective polarizing plate is converted by the polarization converting means and re-enters the reflective polarizing plate.

According to the above construction, the light reflected by the reflection type polarizing plate can be converted by the polarization converting means and re-incident on the reflection type polarizing plate to be used, so that the light incident on the light guide plate can be predetermined. It is possible to increase the brightness of linearly polarized light and improve the light utilization efficiency.

By providing a scattering plate as the polarization converting means, random light can be re-incident on the reflective polarizing plate. Alternatively, as the polarization conversion means, 1 /
By providing a four-wave plate and a reflector, the reflected light
The rotated light can be re-incident on the reflective polarizing plate.

As the polarizing means, a cholesteric liquid crystal film, a 1/4 wavelength plate and a polarizing plate can be used, and the predetermined circularly polarized light transmitted through the cholesteric liquid crystal film is the 1/4 wavelength plate and the polarizing plate. The light reflected by the cholesteric liquid crystal film is reflected by the reflection plate by providing a reflection plate that reflects light reflected by the cholesteric liquid crystal film to the cholesteric liquid crystal film side into a predetermined linearly polarized light. After the rotation direction of the circularly polarized light is converted, the light is transmitted through the cholesteric liquid crystal film and re-incident on the quarter wavelength plate and the polarizing plate.

According to the above structure, the light reflected by the cholesteric liquid crystal film is reflected by the reflecting plate and the rotation direction is reversed to allow the light to pass through the cholesteric liquid crystal film and re-enter the ¼ wavelength plate and the polarizing plate. Since it can be used by making it possible to increase the brightness of the predetermined linearly polarized light incident on the light guide plate, it is possible to improve the light use efficiency.

By providing a condensing means for collimating the light on the light incident side of the polarizing means, the collimated light can be incident on the light guide plate. Since the incident angle in the thickness direction of the light guide plate can be narrowed down, the light utilization efficiency can be improved and the design for optimizing the prism shape can be facilitated.

As the polarization means, a beam splitter for polarization-separating the light from the light source into transmitted light and reflected light can be used, and the predetermined polarized light transmitted through the beam splitter is incident on the guide rod, Further, a reflecting plate for reflecting the reflected light reflected by the beam splitter in the direction of the guide rod, and a polarization conversion means for converting the light reflected by the reflected light into the same linear polarized light as the transmitted light are provided. Thus, the reflected light reflected by the beam splitter is reflected by the reflector in the direction of the guide rod, converted into the same linear polarized light as the transmitted light by the polarization conversion means, and incident on the guide rod. Alternatively, the reflected light reflected by the beam splitter is converted by the polarization conversion means to be converted into the same linearly polarized light as the transmitted light, and the converted light is reflected by the reflecting plate in the guide rod direction to guide the light. It may be incident on the Lloyd. According to the above configuration, the light having a high degree of polarization separated by the beam splitter can be incident on the light guide plate via the guide rod, so that the light utilization efficiency can be improved.

By providing a half-wave plate as the polarization conversion means, the reflected light reflected by the beam splitter is rotated by 90 °, converted into the same linear polarized light as the transmitted light, and incident on the light guide plate. Therefore, the light utilization efficiency can be improved.

By providing a condensing means for collimating the light on the light incident side of the polarizing means, the collimated light can be incident on the guide rod and the light guide plate. Since the incident angle in the thickness direction of the guide rod and the light guide plate can be narrowed, it is possible to improve the light utilization efficiency and facilitate the design for optimizing the prism shape.

At least one of the surface on the light guide plate side and the surface on the opposite side of the guide rod is provided with an uneven portion for uniformizing the light incident on the light guide plate, so that the light is incident on the light guide plate. The emitted light can be made into a uniform linear light.

A front light according to the fourth aspect of the present invention is a point light source, a guide rod for converting light incident from the point light source into uniform linear light and outputting the linear light, and one of the light from the guide rod. It is arranged so that it is incident on the inside from the side surface, and one surface is flat and the other surface is specularly reflected with a gentle slope part that totally reflects the light totally reflected by the flat surface. And a light guide plate formed in an uneven shape having a steep slope portion to be emitted from the other surface, the guide rod,
It has a polarization function of making the light from the point light source enter the light guide plate in a predetermined polarization state.

According to the above configuration, the fourth embodiment described later
As shown in FIG. 3, the guide rod can make the light emitted from the point light source uniform like a linear light source and enter the light guide plate. Furthermore, by the guide rod itself,
Since the light incident from the point light source through the guide rod can be made to enter the light guide plate in a predetermined polarization state, the number of parts can be reduced as compared with the first to third inventions. Compared to the case where general light source light whose polarization state is not constant is incident on the light guide plate, the prism-shaped concavo-convex shape formed on the side of the light guide plate on which the external light is incident (display surface side) is optimal. It is possible to reduce the amount of light leaked to the display surface side depending on the angle of light incident on the inclined surface portion of the light guide plate and the prism shape by performing an optimized design. As a result, it is possible to prevent the visibility of the display image from being deteriorated due to the leaked light. Furthermore, in the light guide plate, the incident light travels while maintaining the polarization plane,
Predetermined polarized light can be emitted from the light guide plate, and most of the predetermined polarized light is displayed by aligning the polarization plane of the polarizing plate provided on the light incident side of the reflective display panel with the optical axis of the predetermined polarized light. Can be used to improve the efficiency of light utilization.

As the guide rod, a plurality of translucent light guides each having an inclined surface inclined at a predetermined angle with respect to the light incident direction are formed by joining the inclined surfaces to each other. By using a light source configured to convert the light from the point light source into the predetermined linearly polarized light, the guide rod itself can have a polarization function for obtaining the predetermined polarized light. Alternatively, as the guide rod,
A plurality of light-transmitting light guides each having an inclined surface inclined at a predetermined angle with respect to the light incident direction are configured by joining the inclined surfaces to each other, and the light from the point light source is provided in a predetermined manner. It has a pair of rod bodies configured to be linearly polarized light, and the inclination directions of the inclined surfaces of the translucent light guide body in each rod body are opposite to each other. By using the light from which the light from each of the light sources is incident, the guide rod itself can have a polarization function for obtaining a predetermined polarization.

As the light source, a light emitting diode (LE
By using D), lower power consumption can be achieved as compared with the case where a cold cathode tube is used. Further, unlike a cold cathode tube including a plurality of emission spectra, an LED emits light having a specific spectrum. Therefore, a design for optimizing the prism shape on the surface of the light guide plate and a polarization function of the guide rod are required. Design for optimization becomes easy.

At the periphery of the light guide plate, a reflection plate is provided on at least one side surface other than the side surface facing the light source or the guide rod, so that light leakage from the side surface of the light guide plate is reduced and light utilization efficiency is improved. Can be improved.

A polarizing plate is provided on the light exit side of the light guide plate,
By aligning the polarization axis of the predetermined polarized light emitted from the light emitting surface of the light guide plate with the polarization plane, compared with the case of transmitting general light source light whose polarization state is unspecified, after passing through the polarizing plate It is possible to reduce the decrease in the brightness of.

A polarizing plate is provided on the outside light incident surface side (display surface side) of the light guide plate, and the polarization axis of a predetermined polarization emitted from the light emission surface of the light guide plate is made to coincide with the polarization plane. It is possible to reduce unnecessary leakage light to the display surface side and improve the visibility of the display image. Alternatively, a polarizing plate and a retardation plate are provided on the outside light incident surface side of the light guide plate, and a polarization axis of a predetermined polarization emitted from the light exit surface of the light guide plate, and the outside light of the polarizing plate and the retardation plate. Unnecessary leaked light to the display surface side can also be reduced by matching the polarization axis of the polarized light obtained by passing through the retardation plate.

A polarizing plate is provided on the outside light incident surface side (display surface side) of the light guide plate, and a predetermined polarized light emitted from the light exit surface of the light guide plate is made to be orthogonal to the polarized light surface. It is possible to further reduce the unnecessary leakage light to the display and improve the visibility of the display image. With this configuration, it is possible to obtain a display function in which the negative and positive are reversed depending on whether the illumination light emitted from the light source through the light guide plate is used or the external light is used.

The reflection type display device of the present invention has the front light and the reflection type display panel of the present invention, and displays light by irradiating the reflection type display panel with light emitted from the front light or external light. It can be carried out.

Further, a polarizing plate is provided on the outside light incident surface side (display surface side) of the light guide plate so that the polarization axis of a predetermined polarization emitted from the light exit surface of the light guide plate is orthogonal to the polarization plane. In the configuration, by inverting the drive signal when performing display using the emitted light from the front light and the drive signal when performing display using external light, the light source emits light through the light guide plate. It is possible to obtain a display in which the negative and positive are the same when the illumination light is used and when the external light is used.

By irradiating the reflection type display panel with the light emitted from the front light or the external light and reflecting the light in a direction deviated from the regular reflection direction, as shown in Embodiment 5 described later, Since the display light that is incident on the mold display panel and reflected therefrom and the specularly reflected light are not mixed, a decrease in contrast is suppressed and the visibility of the display image can be improved.

In the reflective display panel, a reflective hologram can be used as a means for reflecting the light emitted from the front light or the external light in a direction deviated from the regular reflection direction. Alternatively, a reflective plate provided with a plurality of inclined surfaces inclined with respect to the display surface can be used.

[0047]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a perspective view for explaining a schematic configuration of a front light which is an embodiment of the present invention. The front light 10 has a light guide plate 12 made of a translucent resin such as an acrylic resin or a polycarbonate resin.

FIG. 2 is a sectional view of the main part of the light guide plate 12.
Concavities and convexities are provided on one surface of the light guide plate 12.
The concavities and convexities provided on the surface of the light guide plate 12 are adjacent to a plurality of mutually parallel first slopes (slow slopes) 12a arranged along the width direction of the light guide plate 12 at appropriate intervals. And a plurality of second slopes (steep slopes) 12b that are arranged in parallel with each other and that are respectively arranged between the first slopes 12a. Each of the second slopes 12b is inclined in a direction opposite to that of the first slope 12a at an inclination angle larger than that of the first slope 12a. The back surface of the light guide plate 12 is a flat illumination light emitting surface 12c. A cylindrical linear light source 11 formed of a cold cathode tube or the like is arranged on the side of the light guide plate 12 so as to face one side surface along the width direction.

FIG. 3 is a sectional view of the linear light source 11 and its surroundings in the front light 10. Linear light source 11
On the side surface of the light guide plate 12 facing the reflection polarizing film 1
4 is provided over the entire surface, and this reflective polarizing film 1
A prism sheet 13 as a light condensing unit is laminated on the surface 4. Further, a scattering reflection plate 15 is provided so as to surround the linear light source 11, and light emitted from the linear light source 11 and traveling in a direction different from the light guide plate 12 is scattered and reflected by the scattering reflection plate 1.
The light is scattered by 5 and reflected toward the light guide plate 12. Further, as shown in FIG. 1, the linear light source 1 in the light guide plate 12 is provided.
The reflector plate 1 is provided on the other three side surfaces except the side surface facing 1.
6 are provided on the respective side surfaces of the light guide plate 12 with the reflecting surfaces facing each other.

FIG. 4 is a sectional view showing a schematic structure of a reflection type display device which is an embodiment of the present invention provided with a front light having such a structure. This reflection type display device has an external light incident side (display surface side) of the reflection type display panel 20.
The light guide plate 12 of the front light 10 shown in FIG. The light guide plate 12 has a surface provided with concavities and convexities facing the side opposite to the reflective display panel 20, and external light is incident on the surface. The reflective display panel 20 includes a first substrate 21 having a light-transmitting property, which is disposed on a display surface side which is an incident side of external light, and a second light-transmitting substrate which is disposed on a side opposite to the display surface side. The substrate 22 and the substrate 22 are arranged at a predetermined interval. An electro-optical material 23 such as a liquid crystal is held in the space between the two substrates 21 and 22, and the substrates 21 and 2 are
2 has a transparent electrode 24 and 25 for applying a voltage to the electro-optical material 23.
Are provided respectively. The reflecting plate 26 has a reflecting surface on the surface of the second substrate 22 opposite to the electrode forming surface.
It is provided to face. Further, a quarter wave plate 28 is provided on the display surface of the first substrate 21, and a polarizing plate 27 is provided on the quarter wave plate 28.

When displaying an image in such a reflective display device, in order to change the electro-optical characteristics of a predetermined region of the electro-optical material 23, the translucent electrode 2 is used.
A voltage is applied to 4 and 25. As a result, the electro-optical characteristics of the electro-optical material 23 change. In this case, external light is incident on the reflective display panel 20 through the light guide plate 12 of the front light 10, and the incident light is transmitted through the electro-optical material 23 having the changed electro-optical characteristics and reflected by the reflection plate 26. It The reflected light is reflected by the quarter-wave plate 28, the polarizing plate 27, and the light guide plate 12 of the front light 10.
It is possible to visually recognize it as a display image by being emitted through. On the other hand, when external light is scarce when visually recognizing the display image, the linear light source 11 of the front light 10 is used.
Is lit. In this case, as shown in FIG. 2, the light source light 31 emitted from the linear light source 11 is in a randomly polarized state, and is directly or reflected by the scattering reflection plate 15 and transmitted through the prism sheet 13 as the light converging means. Then, the light is incident on the reflective polarizing film 14 as the polarizing means. Of this incident light, only the P-polarized component 32 is reflected by the reflective polarizing film 14
The S-polarized component 33 orthogonal to the P-polarized component is transmitted to the light guide plate 12 and reflected by the reflective polarizing film 14 toward the light source 11. The S-polarized light component 33 reflected in the direction of the light source 11 is scattered by the scattering reflection plate 15 as the polarization conversion means or the cold cathode tube of the linear light source 11 to be converted into light having a random polarization state (random light) and reflected. It is re-incident on the polarizing film 14. Then, the reflective polarizing film 14
Thus, of the re-incident light 34, only the P-polarized component 35 is incident on the light guide plate 12.

The light guide plate 1 is transmitted through the reflective polarizing film 14.
The light incident on the first light source 2 enters the first slope 1 of the surface provided with the unevenness.
It is totally reflected by 2a and the illumination light emitting surface 12c on the back surface and travels in the light guide plate 12. At this time, when the light traveling in the light guide plate 12 enters the second inclined surface 12b on the surface,
The traveling direction changes due to regular reflection on the slope 12b,
The light is emitted as illumination light through the illumination light emission surface 12c without being totally reflected by the illumination light emission surface 12c. Light guide plate 1
The light traveling in 2 travels in the light guide plate 12 by repeating the total reflection by the first inclined surface 12a and the illumination light emitting surface 12c, so that the polarization plane is maintained.

In this way, the illumination light in a state of being almost linearly polarized is incident on the polarizing plate 27 provided so that the polarization axis of the illumination light and the polarization plane coincide with each other. Accordingly, most of the light emitted from the light guide plate 12 as the illumination light is used for visually recognizing the display image. As a result, the utilization efficiency of the light emitted from the front light 10 is significantly improved.

Incidentally, the front light 1 of the first embodiment
In 0, the cylindrical linear light source 11 arranged along the side surface of the light guide plate 12 was used, but instead of this configuration, as shown in FIG. 5, an LED (light emitting diode) 51 which is a point light source.
It is also possible to use a plurality of. In this case, each LED
51 is arranged facing the side surface of the light guide plate 12 with an appropriate interval. By using the plurality of LEDs 51 in this way, low power consumption can be achieved.

Further, the linear light source 11 serves as a polarization conversion means.
Although the scattering reflection plate 15 that surrounds the LED is used, as shown in FIG. 5, between the adjacent LEDs 51, a quarter-wave plate 52 arranged so as to face the side surface of the light guide plate 12, and this quarter wave plate 52 are arranged.
You may use the reflection plate 53 laminated on the opposite side to the light guide plate 12 of the wave plate 52. In this way, by using the quarter-wave plate 52 and the reflection plate 53 as the polarization conversion means, the light reflected by the reflective polarization film 14 is converted into the light rotated by 90 °, and is re-incident on the reflective polarization film 14. Can be made. In this case, the illumination light having a higher degree of polarization can be obtained as compared with the case where the scattering reflector is used.

(Second Embodiment) FIG. 6 is a perspective view for explaining a schematic configuration of a front light which is another embodiment of the present invention. The front light 60 has the light guide body 12 having the same configuration as that of the first embodiment. Light guide 1
On the side of 2, facing one side surface along the width direction,
A guide rod 62 is arranged along the side surface.
The guide rod 62 is made of a translucent resin such as an acrylic resin or a polycarbonate resin and has a quadrangular cross section, and the LED 51 as a point light source is arranged on each end face. The light emitted from each point light source 51 and incident on the guide rod 62 is converted into a uniform linear light source by the guide rod 62, and the side surface of the light guide plate 12 facing the guide rod 62 is irradiated with the light.

On the side surface of the light guide plate 12 irradiated with the light from the guide rod 62, a reflective polarizing film 14 is provided over the entire surface, and the prism sheet 13 as a condensing means is laminated on the reflective polarizing film 14. ing.
Further, a scattering reflection plate 66 is provided so as to surround the periphery of the guide rod 62, and the light that is incident on the guide rod 62 from the point light source 51 and that travels in the guide rod 62 is scattered and directed toward the light guide plate 12. Is reflected. Reflecting plates 16 are provided on the other three side surfaces of the light guide plate 12 excluding the side surface facing the guide rod 62, with the reflecting surfaces facing the respective side surfaces of the light guide plate 12.

FIG. 7 is a plan sectional view of the point light source 51 and its surroundings in the front light 60. On the side surface of the guide rod 62 of the front light 60 facing the light guide plate 12, a plurality of V grooves 62a having a V-shaped cross section are formed.
Are arranged along the up-down direction, with appropriate intervals in the longitudinal direction. The side surface of the guide rod 62 provided with each V groove 62a is a light scattering / transmitting portion 62b except for each V groove 62a. In addition, each V groove 62
The side surface facing the side surface of the guide rod 62 provided with a is a scattering reflection portion 62c that reflects light in a scattered state over the entire surface.

The front light 60 having such a structure is
The light guide plate 12 is arranged on the polarizing plate 27 on the outside light incident side (display surface side) of the reflection type display panel 20 shown in FIG. 2 to form a reflection type display device.

In such a reflection type display device, the light source light emitted from the point light source 51 of the front light 60 is incident on the guide rod 62 in a randomly polarized state. The light incident on the guide rod 62 is directly or in the V groove 62a.
And is incident on the scattering reflection portion 62c on the side surface facing the V groove 62a. Then, this scattering reflection unit 62
The light reflected by c is transmitted through the scattering / transmitting portion 62b in a scattered state. The light transmitted through the scattering / transmitting portion 62b is transmitted through the prism sheet 13 as a condensing unit and is incident on the reflective polarizing film 14 as a polarizing unit. Of this incident light, only the P-polarized component passes through the reflective polarizing film 14 and enters the light guide plate 12, and the S-polarized component orthogonal to the P-polarized component is reflected by the reflective polarizing film 14 toward the guide rod 62. S reflected in the direction of the guide rod 62
The polarized component is transmitted through the scattering / transmitting unit 62b, is reflected by the scattering / reflecting unit 62c as a polarization converting unit, is converted into light having a random polarization state (random light), and is re-incident on the reflective polarizing film 14. Then, the reflective polarizing film 14
Therefore, only the P-polarized component of the re-incident light is guided to the light guide plate 12.
Is injected inside.

The light guide plate 1 is transmitted through the reflective polarizing film 14.
The light that has entered inside 2 is emitted as illumination light from the illumination light emission surface 12c with the polarization plane maintained, as in the first embodiment. Then, the illumination light in a state of being substantially linearly polarized enters the polarizing plate 27 provided so that the polarization axis of the illumination light and the polarization plane coincide with each other. Thereby, most of the light emitted as the illumination light can be used for visually recognizing the display image.

In the second embodiment, the reflective polarizing film 14 is used to make the light incident on the light guide plate 12 from the guide rod 62 into a predetermined linearly polarized light.
The light reflected by 4 was converted into random light by the scattering reflector 62c. Instead of this configuration, as shown in FIG.
A cholesteric liquid crystal film 84 as a polarizing means,
Quarter-wave plate 85 and polarizing plate 8 as polarization converting means
It is also possible to use a laminate in which 6 and 6 are sequentially laminated. In the laminated body, the polarizing plate 86 is laminated on the side surface of the light guide plate 12,
The liquid crystal film 84 is opposed to the guide rod 62.

In this case, the predetermined circularly polarized light transmitted through the cholesteric liquid crystal film 84 is made incident on the quarter-wave plate 85 and the polarizing plate 86, and is made incident on the light guide plate 12 as the predetermined linearly polarized light. Further, the reflected light reflected by the cholesteric liquid crystal film 84 is reflected by the reflecting plate 16 provided on the side surface of the guide rod 62 facing the light guide plate 12, passes through the cholesteric liquid crystal film 84, and is ¼
The light is re-incident on the wave plate 85 and the polarizing plate 86. In this way, a predetermined linearly polarized light can be finally made incident on the light guide plate 12, and illumination light having a higher degree of polarization can be obtained. Moreover, in this case, the scattering reflector 62
Since the brightness of light having a predetermined polarization state can be increased as compared with the case where c is used, the light utilization efficiency can be improved.

(Third Embodiment) FIG. 9 is a top view for explaining a schematic structure of a front light which is another embodiment of the present invention. The front light 90 has the light guide 12 similar to that of the first embodiment. A wedge-shaped light guide 96 as a guide rod for converting the light from the point light source into a uniform linear light source and entering the light guide plate is arranged opposite to the side surface of the light guide 12. The wedge-shaped light guide 96 is made of a translucent resin such as acrylic resin or polycarbonate resin. The wedge-shaped light guide 96 is the opposite light guide 1.
The two side surfaces are in close contact with each other, and the far side surface of the light guide 12 is inclined with respect to the facing side surface of the light guide pair 12. Then, the inclined side surface substantially coincides with the opposite side surface of the light guide plate 12 at one end portion, and thus the planar shape is wedge-shaped.

An LED 51, which is a point light source, is arranged on the end surface of the wedge-shaped light guide 96 via a beam splitter 93 and a prism sheet 92. The beam splitter 92 splits the light emitted from the LED 51 into P-polarized light that directly enters the wedge-shaped light guide 96 and S-polarized light that is used in the direction away from the light guide plate 12. On the side of the beam splitter 92, a reflection plate 94 that reflects the S-polarized light separated by the beam splitter 93 so as to irradiate the end face of the wedge-shaped light guide 96 is provided.
4 is provided so as to be inclined with respect to the end face. Further, on the end surface of the wedge-shaped light guide 94 facing the reflection plate 94,
1 / for converting the polarization of the light reflected by the reflector 94
A two-wave plate 95 is provided.

FIG. 10 is a plan sectional view of the point light source 51 and its surroundings in the front light 90. On the side surface of the wedge-shaped light guide 96 which is arranged on the far side of the light guide plate 12 in an inclined state, a flat surface portion 96a parallel to the side surface facing the light guide plate 12 is arranged with an appropriate interval, and A plurality of slope portions 96b having an angle of 135 ° with each flat portion 96a are provided between the adjacent flat portions 96a, and the flat portions 96a and the slope portions 96b form irregularities.

The front light 60 having such a structure also
The light guide plate 12 is arranged on the polarizing plate 27 on the outside light incident side (display surface side) of the reflection type display panel 20 shown in FIG. 2 to form a reflection type display device.

In such a reflective display device, the light source light emitted from the LED 51, which is a point light source, is incident on the prism sheet 92 in a randomly polarized state, converted into substantially parallel light, and incident on the beam splitter 93. The polarized light is separated into P-polarized light and S-polarized light. The P-polarized light is transmitted through the beam splitter 93 and is incident on the light-transmitting wedge-shaped light guide 96, and the S-polarized light is reflected by the beam splitter 93 in the direction of 90 ° with respect to the incident direction (left side in FIG. 10). It The S-polarized light reflected by the beam splitter 93 is reflected by the reflection plate 94 toward the end face of the wedge-shaped light guide 96, rotated by 90 ° by the ½ wavelength plate 95 serving as a polarization conversion means, and guided by the wedge-shaped light. The light enters the light body 96.

The light that has entered the wedge-shaped light guide 96 is flat on the far side of the light guide plate 12 on the inclined side surface 9.
6a and the side surface facing the light guide plate 12, while being repeatedly totally reflected, are specularly reflected by the inclined surface portions 96b arranged between the respective flat surface portions 96a and pass through the side surface facing the light guide plate 12. And enters the light guide plate 12. The light thus entering the light guide plate 12 is emitted from the illumination light emitting surface 12c while maintaining the polarization plane. Then, the illumination light in a state of being substantially linearly polarized enters the polarizing plate 27 provided so that the polarization axis of the illumination light and the polarization plane coincide with each other. Thereby, most of the light emitted as the illumination light is used for visually recognizing the display image.

In the third embodiment, the S-polarized light reflected by the beam splitter 93 is reflected by the reflecting plate 94 toward the end face of the wedge-shaped light guide 96, and then ½.
Although the wavelength plate 95 converts the same polarized light as the transmitted light (P polarized light) and re-enters the wedge-shaped light guide 96, the S reflected by the beam splitter 93 is replaced with this structure.
The same polarization as the transmitted light (P
After being converted into polarized light, the wedge-shaped light guide 96 is converted by the reflection plate 94.
You may make it re-inject.

In the third embodiment, the illumination light emitted from the front light 90 is a linearly polarized light having a higher degree of polarization than that of the second embodiment. Therefore, as shown in FIG. Instead of the polarizing plate 27 provided, a polarizing plate 29 may be provided on the display surface side. In this case, by matching the polarization axis of a predetermined linearly polarized light emitted from the light guide plate 12 of the front light 90 with the polarization plane of the polarizing plate 29, only the same linearly polarized light as the illumination light is present on the display surface side. Are transmitted, so that unnecessary light not related to display is prevented from leaking to the display surface side, and a display image with high contrast can be obtained.

Further, a polarizing plate and a retardation plate are provided on the display surface side, and predetermined linearly polarized light emitted from the light guide plate 12 of the front light 90 and external light are passed through the polarizing plate and the retardation plate. By setting the obtained polarized light so that it matches the polarized light, the light leaked to the display surface side can be reduced, so that a display image with high contrast can be obtained.

Furthermore, when a polarizing plate is provided on the display surface side, the polarization axis of a predetermined linearly polarized light emitted from the light guide plate 12 of the front light 90 is set to be orthogonal to the polarizing surface of the polarizing plate. Thus, only the linearly polarized light whose polarization axis is orthogonal to the predetermined linearly polarized light is transmitted to the display surface side. This makes it possible to block light that is not emitted from the light guide plate 12 of the front light 90 to the reflective display panel 20 side and is directly emitted to the display surface side, so that unnecessary light not related to display is displayed on the display surface side. It is possible to obtain a display image with higher contrast by suppressing the leakage of the liquid crystal into the display image.

Further, in this configuration, since the external light is transmitted through the polarizing plate and is applied to the reflection type display panel, when the external light is used, in order to display an image, a straight line orthogonal to the illumination light is used. Polarized light is used. Therefore, a display image in which the negative and the positive are reversed is obtained depending on whether the image is displayed by using the illumination light from the light guide plate 12 of the front light 90 or when the image is displayed by using the external light. By inverting the drive signal applied to the electrodes when displaying an image using illumination light and the drive signal applied to the electrodes when displaying an image using external light, Even when using the light of, it is possible to obtain a display image in which the negative image and the positive image are the same.

Further, when a polarizing plate is provided on the display surface side (the frontmost surface of the reflection type display device), the display surface is hard-coated and non-reflective as used in the conventional reflection type display device. The coating process, touch panel technology, etc. can be used as they are.

(Embodiment 4) FIG. 12 is a plan view for explaining a schematic structure of a front light which is another embodiment of the present invention. The front light 120 has the light guide 12 similar to that of the first embodiment. Light guide 12
A guide rod 123 is arranged laterally on the side of the one side, facing one side surface along the width direction. As shown in FIG. 13, the guide rod 123 has a block-shaped translucent light guide 123a made of acrylic resin, polycarbonate resin, or the like. Each translucent light guide 123
a has inclined surfaces that are inclined at 45 ° with respect to the side surfaces of the light guide plate 12, and by attaching the inclined surfaces provided on each translucent light guide 123a to each other with an adhesive 123b, The guide rod 123 has a rectangular cross section.

LE, which is a point light source, is provided on one end surface of the guide rod 123 via a prism sheet 122.
D51 is arranged. The light emitted from the LED 51 is converted into parallel light by the prism sheet 122 and enters the guide rod 123. Further, on the other end surface of the guide rod 123 facing the point light source 51,
A quarter-wave plate 125 is provided, and a reflection plate 126 is laminated on the outside thereof. Further, a reflecting plate 16 is provided on each of the other three side surfaces of the light guide plate 12 excluding the side surface facing the guide rod 123 and the side surface of the guide rod 123 opposite to the side surface facing the light guide plate 12. There is. The reflecting surface of each reflecting plate 16 faces the side surfaces of the light guide plate 12 and the guide rod 123.

The front light 120 having such a configuration
Also, the light guide plate 12 is arranged on the polarizing plate 27 on the outside light incident side (display surface side) of the reflection type display panel 20 shown in FIG. 2 to form a reflection type display device.

In such a reflection type display device, the light source light emitted from the LED 51, which is a point light source, is incident on the prism sheet 122 in a randomly polarized state, converted into substantially parallel light, and incident on the guide rod 62. To be done. Of the light that has entered the guide rod 123, the S-polarized component is reflected at the interface between each translucent light guide 123a and the adhesive 123b, and is emitted toward the light guide plate 12. On the other hand, the P-polarized light transmitted through the inside of the guide rod 123 from the end on the incident side to the end on the opposite side, the quarter-wave plate 125 arranged at the end.
The light is rotated by 90 ° by the reflection plate 126, reflected as S-polarized light, and re-incident on the guide rod 123. The light that is re-incident on the guide rod 123 receives the light-transmitting light guide 12.
The light partially transmitted at the interface between 3a and the adhesive 123b, partially reflected at the interface, and reflected at the interface is once reflected by the reflection plate 127 and then emitted toward the light guide plate 12. The light that has entered the light guide plate 12 is emitted from the illumination light emission surface 12c with the polarization plane maintained.

In this way, as in the first embodiment,
Illumination light emitted from the light guide plate 12 in a state of being almost linearly polarized enters the polarizing plate 27 provided so that the polarization axis of the illumination light and the polarization plane coincide with each other. Thereby, most of the light emitted as the illumination light is used for visually recognizing the display image.

As described above, the guide rod 123 of the front light 120 has a polarization function for obtaining a predetermined polarization. In addition, the guide rod 123 makes the difference between the refractive index of the block-shaped light-transmitting light guide 123a and the refractive index of the adhesive 123b inclined at 45 ° with respect to the side surface of the light guide 12 within 3%. Bring the Brewster angle closer to 45 °
I have to. In addition, the reflectance is increased by providing a large number of boundary surfaces between the light-transmitting light guides 123a, and the reflectance due to the approach of the refractive indexes of the light-transmitting light-guide 123a and the adhesive 123b. Is prevented from falling. Furthermore, since a large number of boundary surfaces are provided between the translucent light guide members 123a, the distribution of the emitted light is made uniform.

In this embodiment, as the guide rod, similar to the above-mentioned guide rod 123, the block-shaped light-transmitting light guides each having an inclined surface inclined at 45 ° with respect to the side surface of the light guide plate 12. The body may be configured by a pair of rod bodies configured by joining the respective inclined surfaces. In this case, the end faces of each rod body are ¼
It is joined via a wave plate and a reflector. In addition, the inclined surfaces of the translucent light guides of the rod bodies are inclined in opposite directions. Then, the LEDs 51 as point light sources are arranged on the end faces located on the outside of each rod body, and the light emitted from each LED 51 is incident on each rod body.

(Fifth Embodiment) FIG. 14 is a cross-sectional view for explaining a schematic structure of a reflection type display device which is another embodiment of the present invention. This reflective display device 140 is different from the reflective display device of the first embodiment in that instead of the reflective plate 26 arranged outside the second substrate 22 of the reflective display panel 20 shown in FIG. Is used. Other configurations are the same as those of the first embodiment shown in FIG.
It is similar to the reflection type display device. This hologram reflection plate 141 is produced, for example, by irradiating a hologram recording film manufactured by DuPont with a laser beam of two light fluxes to perform interference exposure. The light incident on the hologram reflection plate 141 is reflected in a direction deviated from the regular reflection direction. In addition, the light guide plate 1 in the front light 10
By controlling the inclination angle of the uneven shape provided on the surface of 2,
The illumination light 140A emitted from the illumination light emission surface 12c is configured to be inclined about 30 ° from the normal line direction of the display surface. With such a configuration, the reflective display panel 20
The display light 140B that is transmitted through the hologram reflection plate 141 and reflected by the hologram reflection plate 141 is reflected in the normal direction of the display surface, and the light 140C specularly reflected by the surface of the reflective display panel 20 is the normal direction of the display surface. Is reflected in a direction inclined by about 30 °.
As a result, the display light 140B and the light 140C unnecessary for display are not mixed.

In the reflection type display device 140 according to the fifth embodiment, the front light 10 is turned on when the display image is visually recognized and external light is scarce, and the reflection type display panel 2 is displayed.
0 is irradiated with light. In this case, since the display light 140B and the light 140C unnecessary for display are not mixed, it is possible to obtain a display image with high contrast. Further, when there is sufficient external light, a bright and easily visible display image can be obtained even if the front light 10 is turned off.

In the fifth embodiment, the hologram reflection plate 141 is used as the reflection plate, but the front light 1
It is not limited to this as long as it can reflect the light emitted from 0 or the external light in the direction deviated from the regular reflection direction. For example, a combination of a large number of fine reflection surfaces inclined with respect to the display surface is combined. It is also possible to use a reflector. Furthermore, in the fifth embodiment, the reflector is installed on the back surface of the reflective display panel 20, but the reflector may be installed inside the reflective display panel 20.

[0087]

As described in detail above, according to the reflection type display device of the present invention, when the external light is scarce, the front light of the present invention which emits a predetermined polarized light as the illumination light is turned on. The use efficiency of light from the light source can be improved. Therefore, the display brightness of the reflective display device can be improved. Further, if the reflective display device has the same display brightness, the power consumption can be reduced. further,
Since light leaking to the display surface side can be reduced, display with high contrast can be obtained. Furthermore, by making the polarization axis of the predetermined linearly polarized light emitted from the light source through the light guide plate coincide with the polarization plane of the polarizing plate, it is possible to further reduce unnecessary leakage light to the display surface side. According to this configuration, it is possible to perform the display in which the negative and the positive are inverted depending on whether the display is performed by using the illumination light or the external light. Furthermore, by disposing a polarizing plate on the display surface side of the reflective display panel, it is possible to use the conventionally used hard coating treatment, non-reflection coating treatment, touch panel technology, etc.
Further, the front light is turned on by combining the reflection type display panel which reflects the light emitted from the front light or the external light in the direction deviated from the regular reflection direction for display and the front light of the present invention. Not only the time, but also when the front light is turned off, a bright display with high contrast can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view for explaining a schematic configuration of a front light according to a first embodiment.

FIG. 2 is a cross-sectional view for explaining a detailed configuration of the front light according to the first embodiment.

FIG. 3 is a cross-sectional view for explaining a detailed configuration of a light guide plate in the front light according to the first embodiment.

FIG. 4 is a partial cross-sectional view for explaining the schematic configuration of the reflective display device according to the first embodiment.

FIG. 5 is a perspective view for explaining a schematic configuration of a front light using the LED according to the first embodiment.

FIG. 6 is a perspective view for explaining a schematic configuration of a front light according to a second embodiment.

FIG. 7 is a top view for explaining the detailed configuration of the front light according to the second embodiment.

FIG. 8 is a partial top view for explaining another configuration example of the front light according to the second embodiment.

FIG. 9 is a top view for explaining the schematic configuration of the front light according to the third embodiment.

FIG. 10 is a top view for explaining the detailed configuration of the front light according to the third embodiment.

FIG. 11 is a partial cross-sectional view for explaining another configuration example of the reflective display device according to the third embodiment.

FIG. 12 is a top view for explaining the schematic configuration of the front light according to the fourth embodiment.

FIG. 13 is a partial top view for explaining a detailed configuration of a guide rod having a polarization function in the front light according to the fourth embodiment.

FIG. 14 is a partial cross-sectional view for explaining the schematic configuration of the reflective display device according to the fifth embodiment.

[Explanation of symbols]

10 front lights 11 Linear light source 12 Light guide plate 12a gentle slope of light guide plate 12b The steep slope of the light guide plate 12c Illumination light exit surface of light guide plate 13 Prism sheet 14 Reflective polarizing film 15 Scatter reflector 16 Reflector 20 reflective display panel 21 First substrate 22 Second substrate 23 Electro-optical material 24, 25 translucent electrode 26 Reflector 27 Polarizer 28 1/4 wave plate 29 Polarizer 31 light source 32 P polarization component 33 S polarization component 34 Reincident light 35 P polarization component 51 LED 52 1/4 wave plate 53 Reflector 60 front light 62 Guide rod 62a V groove 62b Scattering / transmitting part 62c scattering reflector 66 Scatter reflector 84 Cholesteric liquid crystal film 85 quarter wave plate 86 Polarizer 90 front light 92 Prism sheet 93 Polarizing beam splitter 94 reflector 95 1/2 wave plate 96 Wedge type light guide 96a Flat part of wedge-shaped light guide 96b Wedge type light guide slope 120 front lights 122 Prism sheet 123 Guide rod 123a Small block light guide forming guide rod 123b Adhesive forming guide rod 125 quarter wave plate 126 reflector 127 reflector 140 reflective display device 140A illumination light 140B display light 140C specular light 141 hologram reflector

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/13357 G02F 1/13357 G09F 9/00 336 G09F 9/00 336B // F21Y 101: 02 F21Y 101: 02 F term (reference) 2H038 AA55 BA06 2H091 FA10X FA23X FA41X FA45X LA16 5G435 AA03 BB12 BB16 DD11 DD13 EE22 FF02 FF03 FF05 FF06 FF08 GG23 GG26 HH04

Claims (28)

[Claims] 1. A light source and a light source are arranged so that light emitted from the light source enters from one side surface to the inside. One surface is flat and the other surface is a flat surface. And a light guide plate formed in a concave-convex shape having a gentle slope that totally reflects the light that is totally reflected and a steep slope that specularly reflects and emits from the other surface; and light that enters the light guide plate from the light source. And a polarization means for bringing the light into a predetermined polarization state. 2. The frontlight according to claim 1, wherein the polarization means converts the light incident on the light guide plate from the light source into linearly polarized light. 3. A point light source, a guide rod for converting light incident from the point light source into uniform linear light and incident on the light guide plate, and light from the guide rod is directed from one side surface to the inside. It is arranged so as to be incident, and one surface is flat and the other surface is specularly reflected by a gentle slope portion that totally reflects the light totally reflected by the flat surface, and is emitted from the other surface. A front light, comprising: a light guide plate having a steep slope portion and formed in an uneven shape; and a polarization unit that makes light entering the light guide plate from the guide rod into a predetermined polarization state. 4. A point light source, a guide rod for converting light incident from the point light source into uniform linear light and incident on the light guide plate, and light from the guide rod is directed from one side surface to the inside. It is arranged so as to be incident, and one surface is flat, and the other surface is specularly reflected by a gentle slope portion that totally reflects the light totally reflected by the flat surface and from the other surface. A front light, comprising: a light guide plate formed in a concave-convex shape having a steep slope portion for emitting light; and a polarizing means for making light incident on the guide rod from the point light source into a predetermined polarization state. 5. The polarizing means is a reflective polarizing plate that transmits a predetermined linearly polarized light and reflects other light. Further, the reflected light reflected by the reflective polarizing plate is random light or 90 °. 5. A polarization conversion means for converting into polarized light is provided, and the light reflected by the reflection type polarizing plate is converted by the polarization conversion means and re-enters the reflection type polarizing plate. Front light according to any one of. 6. The front light according to claim 5, wherein the polarization conversion means is a scattering plate. 7. The front light according to claim 5, wherein the polarization conversion unit includes a quarter-wave plate and a reflection plate. 8. The polarizing means has a cholesteric liquid crystal film, a quarter-wave plate and a polarizing plate, and predetermined circularly polarized light transmitted through the cholesteric liquid crystal film is formed by the quarter-wave plate and the polarizing plate. It has a predetermined linearly polarized light and has a reflecting plate that reflects the light reflected by the cholesteric liquid crystal film to the cholesteric liquid crystal film side, and the light reflected by the cholesteric liquid crystal film is reflected by the reflecting plate to form a circle. The front light according to any one of claims 1 to 4, wherein the front light is transmitted through the cholesteric liquid crystal film and re-incident on the quarter-wave plate and the polarizing plate after the rotation direction of polarized light is changed. 9. The frontlight according to claim 1, wherein a condensing unit for collimating the light is provided on the light incident side of the polarization unit. 10. The polarization means has a beam splitter for polarization-separating the light from the light source into transmitted light and reflected light, and predetermined linearly polarized light transmitted through the beam splitter is incident on the guide rod, Further, a reflection plate for reflecting the reflected light reflected by the beam splitter in the direction of the guide rod, and a polarization conversion means for converting the light reflected by the reflection plate into the same linearly polarized light as the transmitted light are provided. The light reflected by the beam splitter is reflected by the reflector in the direction of the guide rod, is converted into the same linear polarized light as the transmitted light by the polarization conversion means, and is incident on the guide rod. Front light as described. 11. The polarization means has a beam splitter for polarization-separating the light from the light source into transmitted light and reflected light, and predetermined linearly polarized light transmitted through the beam splitter is incident on the guide rod, Further, the beam splitter has a polarization conversion means for converting the light reflected by the beam splitter into the same linearly polarized light as the transmitted light, and a reflecting plate for reflecting the converted light toward the guide rod. 5. The front according to claim 4, wherein the reflected light is converted by the polarization conversion means to be converted into the same linearly polarized light as the transmitted light, and the converted light is reflected by the reflection plate and incident on the guide rod. Light. 12. The front light according to claim 10, wherein the polarization conversion means is a half-wave plate. 13. The condensing means for collimating light is provided on the light incident side of the polarizing means.
The front light according to claim 12. 14. The guide rod has a concavo-convex portion for equalizing incident light to the light guide plate on at least one of a surface on the light guide plate side and a surface on the opposite side thereof. The front light according to any one of 13. 15. A point light source, a guide rod that converts the light incident from the point light source into uniform linear light and outputs the linear light, and the light from the guide rod enters the inside from one side surface. The one surface is flat and the other surface is a gentle slope that totally reflects the light that is totally reflected by the flat surface and a steep slope that specularly emits the light from the other surface. And a light guide plate having a concave and convex shape, the guide rod having a polarization function of causing light from the point light source to enter the light guide plate in a predetermined polarization state. 16. The guide rod is configured such that a plurality of translucent light guides each having an inclined surface inclined at a predetermined angle with respect to a light incident direction are joined to each other. The front light according to claim 15, wherein the front light is configured to convert light from the point light source into a predetermined linearly polarized light. 17. The guide rod is configured such that a plurality of translucent light guides each having an inclined surface inclined at a predetermined angle with respect to a light incident direction are joined to each other. , Having a pair of rod bodies configured to make the light from the point light source into a predetermined linearly polarized light, and the inclination directions of the inclined surfaces of the translucent light guide body in each rod body are in opposite directions. The front light according to claim 15, wherein light from a point light source is incident on each rod body. 18. The front light according to claim 1, wherein the light source is a light emitting diode. 19. The front according to claim 18, wherein a reflective plate is provided on at least one side surface other than the side surface facing the light source or the guide rod in the peripheral edge of the light guide plate. Light. 20. A polarization plane is provided on the light exit side of the light guide plate,
20. The frontlight according to claim 1, further comprising a polarizing plate that matches a polarization axis of a predetermined linearly polarized light emitted from the light emitting surface of the light guide plate. 21. A polarizing plate is provided on the light incident surface side of the light guide plate, the polarization plane of which is aligned with the polarization axis of a predetermined linearly polarized light emitted from the light exit surface of the light guide plate. 1 to
The front light according to claim 19. 22. A polarizing plate and a phase difference plate are provided on the outside light incident surface side of the light guide plate, and a polarization axis of a predetermined polarization emitted from the light exit surface of the light guide plate and outside light are provided. 20. The polarization axes of the polarized light obtained by passing through the polarizing plate and the retardation plate are set to coincide with each other.
Front light according to any one of. 23. A polarizing plate having a polarization plane orthogonal to a polarization axis of a predetermined polarization emitted from the light exit surface of the light guide plate, on the side of the light guide plate on which the external light enters. Front light according to any one of 19. 24. A front light according to any one of claims 1 to 23, and a reflective display panel, wherein the reflective display panel is irradiated with light emitted from the front light or external light. A reflective display device that displays images. 25. A reflection type display comprising the front light according to claim 23 and a reflection type display panel, wherein display is performed by irradiating the reflection type display panel with light emitted from the front light or external light. In a display device, a reflection-type display in which a drive signal when performing display using light emitted from a front light and a drive signal when performing display using external light are in an inverted state. apparatus. 26. A means for irradiating the reflection type display panel with light emitted from the front light or external light and reflecting the light in a direction deviated from a regular reflection direction.
The reflective display device according to claim 4 or claim 25. 27. The reflection type display panel according to claim 26, wherein the reflection type display panel has a reflection type hologram as means for reflecting light emitted from the front light or external light in a direction deviated from a regular reflection direction. Display device. 28. The reflection type display panel is provided with a plurality of inclined surfaces inclined with respect to a display surface as means for reflecting light emitted from the front light or external light in a direction deviated from a regular reflection direction. 27. A reflective plate
The reflective display device according to.