JPH11174214A - Directional reflector and reflective display using the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a reflective display device capable of sufficiently brightening a display viewed from the front. A first light guide member having a plurality of rows of groove-shaped recesses having a V-shaped cross section is opposed to a reflection surface of a reflection member behind a display panel.
4, a second light guide member 15 having a smaller refractive index than the first light guide member 13 is provided, and an interface between the first light guide member and the second light guide member 15 is moved to the surface thereof. Optical interfaces 16a and 16b for reflecting or transmitting the incident light according to the incident angle
The incident light within a predetermined incident angle range incident on the front surface of the first light guide member 13 and the reflected light reflected by the reflecting member 12 are refracted by the optical interfaces 16a and 16b, and the reflected light is converted to the first light. The directional reflector 11 that emits light from the front surface of the light guide member 13 in the front direction is disposed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional reflector and a reflective display using the same.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a reflection type display device has a transmission type display panel 1 such as a liquid crystal display panel.
And a scattering reflector 2 arranged opposite to the rear surface of the display panel 1.

In this reflective display device, external light such as natural light or room light entering from the front of the display panel 1 is reflected by the scattering reflector 2, and the reflected light illuminates the display panel 1 from the back to display. The external light incident from the front is transmitted through the display panel 1 and reflected by the scattering reflector 2 as shown by the arrow in the figure, and becomes light diffused over a wide range, and thereafter, is transmitted to the display panel 1. The light enters from the surface and exits in front of the display panel 1.

In general, a reflective display device is inclined in the direction of the upper edge of the screen (left side in FIG. 4) with respect to the normal of the front screen so that external light is mainly taken in from the upper edge of the screen. Is used in a direction in which bright external light can be obtained, and the display is observed from a front direction, that is, a direction near the normal of the screen, or a direction slightly inclined to the lower edge side of the screen.

[0005]

However, the conventional reflective display device using the scattering reflector 2 has a problem that the display is dark. This is because the light reflected by the scattering reflector 2 diffuses widely in a direction that does not enter the display panel 1, and reflected light that can be used as illumination light is only light in a diffusion range that enters the display panel 1. In addition, even when the light enters the display panel 1, the spread angle of the light emitted in front of the display panel 1 is large, and the brightness of the light emitted in the display observation direction is low.

That is, the display of the display device is usually observed from the front direction (near the direction perpendicular to the screen) as described above. The divergence angle of the light emitted to the observer is large, and some of the emitted light that is emitted toward the front is observed by the observer, and the light that is emitted toward the other oblique directions is hardly observed by the observer. Since it cannot be seen, the display to be observed becomes dark.

The present invention provides a directional reflector capable of emitting reflected light of high luminance in a predetermined direction, and a reflective display capable of sufficiently brightening a display viewed from a predetermined direction. It is intended to provide a device.

[0008]

SUMMARY OF THE INVENTION A directional reflector according to the present invention includes a reflecting member having a flat reflecting surface, a flat front surface,
A first light guide member having a plurality of rows of groove-shaped recesses formed in a rear surface thereof extending in a predetermined direction, and the rear surface facing the reflection surface of the reflection member; and each groove of the first light guide member. A second light-guiding member having a lower refractive index than the first light-guiding member occupying the inside of the first light-guiding member. Optics having at least two inclined surfaces having different inclination angles with respect to a line, wherein a boundary surface between the inclined surface and the second reflecting member reflects or transmits light incident on the boundary surface according to the incident angle. An interface is formed, and light incident from a front surface of the first light guide member in a predetermined incident angle range is emitted in a predetermined direction at a spread angle smaller than the incident angle range of the incident light. According to this directional reflector, reflected light of high luminance is emitted in a predetermined direction. It can be.

Further, the reflection type display device of the present invention reflects incident light from the transmission type display panel and the front surface, which is disposed opposite to the rear surface of the display panel, and reflects the reflected light in a predetermined direction. And a directional reflector that emits toward the front with a divergence angle smaller than the incident angle range of the incident light. According to this reflective display device, a display that is observed from a predetermined direction is provided. Can be made sufficiently bright.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the directional reflector of the present invention has a rear surface of a first light guide member having a plurality of rows of groove-shaped recesses along a predetermined direction on a rear surface of the reflection member. Are opposed to each other, and the first light guide member is provided in each groove-shaped recess.
A second light guide member having a smaller refractive index than the light guide member is provided, and the interface between the first light guide member and the second light guide member is changed to the incident light on the surface by the incident angle. And an optical interface that reflects or transmits according to the optical member, and the optical interface is an inclined surface that is inclined at different directions and inclination angles with respect to a normal line of the reflective surface of the reflective member. The light reflected from the reflection member is refracted at the optical interface, with respect to the normal to the reflection surface of the first light guide member, from the front surface of the first light guide member within a predetermined incident angle range and the reflection light reflected by the reflection member. From the front surface of the first light guide member at a spread angle smaller than the incident angle range of the incident light in a predetermined direction, and emits reflected light of high brightness in a predetermined direction. .

In the directional reflector according to the present invention, the groove-shaped concave portion of the first light guide member may be a groove-shaped concave portion having a V-shaped cross section having two side surfaces inclined at different directions and inclined angles. Has a trapezoidal cross-section having two side surfaces inclined at different directions and inclination angles and a bottom surface substantially parallel to the reflection surface of the reflection member.
If the interface between one side surface and the second light guide member is the selective reflection surface, and the interface between the bottom surface and the second light guide member is the transmission surface, the number of light refraction surfaces increases, First
Using a material having a relatively small refractive index for the light guide member, and emitting the light incident on the front surface of the first light guide member in a predetermined direction at a spread angle smaller than the incident angle range of the incident light. Can be.

Further, the reflection type display device of the present invention reflects incident light from the front of the display panel facing the rear surface of the transmission type display panel, and reflects the reflected light in a predetermined direction. By arranging a directional reflector that emits light in front of the display panel at a divergence angle smaller than the angle range, the display viewed from a predetermined direction is made sufficiently bright.

In this reflective display device, as described above, the directional reflector has a plurality of rows of groove-shaped recesses along a predetermined direction on a rear surface of the reflection member. A second light guide member having a lower refractive index than the first light guide member is provided in each groove-shaped concave portion of the first light guide member with the rear surfaces facing each other. The interface with the second light guide member is an optical interface that reflects or transmits light incident on the surface in accordance with the angle of incidence, and the optical interfaces on both sides of the groove-shaped recess are respectively the reflection member. With respect to the normal of the reflecting surface, the inclined surface is inclined at a different direction and an inclined angle from each other, so that the incident light within a predetermined incident angle range and the reflecting member incident from the front surface of the first light guide member. Refracting the reflected light at the optical interface, From the front surface of the first light guide member, it is emitted at a small spread angle than the incident angle range of the incident light in a predetermined direction, preferably those adapted to emit high intensity of the reflected light in a predetermined direction.

[0014]

1 and 2 show a first embodiment of the present invention. FIG. 1 is a side view of a reflection type display device provided with a directional reflector, and FIG. 2 is a side view of the directional reflector. It is a partially expanded side view.

As shown in FIG. 1, the display device of this embodiment comprises a transmissive display panel 10 and a directional reflector 11 arranged opposite the rear surface of the display panel 10. The display panel 10 is, for example, a liquid crystal display panel. The liquid crystal display panel may be any of an active matrix type, a simple matrix type, a segment type, and the like, and its display method is TN (twisted nematic). System, STN (super twisted nematic) system, ECB (birefringence effect) system,
Any display method for controlling light transmittance, such as a dynamic scattering effect method or a method using a ferroelectric liquid crystal, may be used.

The directional reflector 11 is shown in FIGS.
As shown in FIG. 3, a flat reflecting surface 12a that performs specular reflection.
A reflection member 12 having a flat front surface and a plurality of groove-shaped concave portions 14 formed in a rear surface parallel to each other in a predetermined direction,
A first light guide member 13 having the rear surface opposed to the reflection surface 12a of the reflection member 12, and the first light guide member provided in each groove-shaped recess 14 of the first light guide member 4; The second light guide member 15 has a smaller refractive index than the light guide member 13. The reflecting member 12 is, for example, a flat-surface reflecting film in which silver or aluminum is deposited or plated on at least one entire surface of a resin film, and the reflecting surface 12a is a mirror surface.

The first light guide member 13 is made of a transparent resin material such as acryl or triacetyl cellulose (TAC) (preferably a transparent resin material having no optical anisotropy). A groove-like recess 1 having a length extending over the entire width thereof (the width in the front and back directions of the paper surface in the figure).
A plurality of rows 4 are formed in parallel with each other.

In this embodiment, the first light guide member 13 is bonded to a front transparent plate 13a having a flat plate shape and a rear transparent plate 13b having the groove-shaped recess 14 formed on one surface. Structure.

In the case where the first light guide member 13 is bonded as described above, the front transparent plate 13a and the rear transparent plate 13b are made of a resin material having the same refractive index or a very small difference. And the transparent plates 13a and 13b are
It is desirable that the adhesive is bonded using an adhesive having substantially the same refractive index as that, and in this case, the first light guide member 13 hardly refracts light at the interface between the transparent plates 13a and 13b. It can have a light guiding property that is almost the same as that of an integrally molded article.

The groove-shaped recess 14 formed on the rear surface of the first light guide member 13 is a groove-shaped recess having a V-shaped cross section having two side surfaces inclined in opposite directions. Both side surfaces of the concave portion 14 are inclined at different inclination angles toward the depth direction of the groove-shaped concave portion 14 with respect to the normal of the front surface of the first light guide member 13.

These groove-shaped concave portions 14 are formed parallel to each other at predetermined intervals, and the rear surfaces of the flat portions between the groove-shaped concave portions 14 of the first light guide member 13 are respectively The light guide member 13 has a surface parallel to the front surface.

In FIG. 1, the first light guide member 1 is provided for convenience.
3, the width of each groove-shaped recess 14 formed on the rear surface of the first light guide member 13 (the widest width of the V-shaped groove, for example) ) Is 40 ~
The width is set to an extremely small width of about 100 μm, and at that time, each groove-shaped concave portion 14 is set in parallel at an interval of 50 to 150 μm, and the width of each rear surface of a portion in contact with the reflecting member is:
The width is set to about 凹 部 to の of the width of the groove-shaped recess 14.

The first light guide member 13 has a surface between the respective groove-shaped recesses 14 which is formed on the reflection surface 12 of the reflection member 12.
a, and is adhered on the reflection member 12 with a transparent adhesive (not shown) (a double-sided adhesive tape may be used).

Further, the second light guide member 1 provided so as to occupy the inside of each groove-shaped recess 14 of the first light guide member 13 is provided.
5 is, for example, an air layer. Therefore, the refractive index of the second light guide member 15 is smaller than the refractive index of the first light guide member 13.

The interface between the first light guide member 13 and the second light guide member 15 has an optical interface 16a, which reflects or transmits light incident on the surface according to the angle of incidence.
16b.

The optical interfaces 16a and 16b are respectively
The inclination angle θ1 of one optical interface 16a with respect to the normal line of the front surface of the first light guide member 13 and the reflection surface 12a of the reflection member 12 and the inclination angle θ2 of the other optical interface 16b are θ.
1> θ2.

In the directional reflector 11, as shown in FIG. 1, the optical interfaces 16a, 16a on both sides of the groove-shaped recess 14 are provided.
6b, the optical interface 16a having the larger inclination angle with respect to the normal of the reflection surface 12a of the reflection member 12 (the inclination angle θ
1) is directed toward the upper edge side (left side in FIG. 1) of the screen (the front surface of the display panel 10) which is the main external light capturing direction of the display device, and the optical interface 16b having the smaller inclination angle (the inclination angle) θ2) is arranged behind the display panel 10 toward the observer located on the lower edge side of the screen.

This display device displays the screen of the display device,
In other words, external light such as natural light or room light incident on the front surface of the display panel 10 is reflected by the directional reflector 11, and the reflected light is used to illuminate the display panel 10 from the rear surface for display. The external light incident on the front surface of the display panel 10 is transmitted through the display panel 10 and reflected by the directional reflection plate 11 as shown by an arrow in the figure, and is incident on the display panel 10 again from the rear surface thereof, and the display panel 10 Out of the front of the device.

In this case, the reflection type display device observes the direction inclined to the upper edge of the screen with respect to the direction perpendicular to the screen toward the direction in which bright external light can be obtained, from the direction inclined to the lower edge. Therefore, external light is mainly taken in from the upper edge side of the screen.

In the case of the reflection type display device of this embodiment, the first light guide member 13 of the directional reflection plate 11 is provided.
Of the optical interfaces 16a, 16b on both sides of the groove-shaped concave portion 14, the optical interface 16a having the larger inclination angle with respect to the normal line of the reflection surface 12a of the reflection member 12 is arranged in a state facing the upper edge side of the screen. Optical interface 16b with smaller inclination angle
Is directed to the lower edge side of the screen, so that light incident on the front surface of the display panel 10 and transmitted through the display panel 10
The light mainly enters the optical interface 16a having the larger inclination angle with respect to the normal to the front surface of the first light guide member 13 constituting the directional reflection plate 11.

Light incident on the directional reflector 11 from the above-described direction is reflected at various angles of incidence as shown by arrows in FIG.
And is refracted at the interface between the front surface and the outside air (air).

The light that has entered the first light guide member 13 passes through the inside of the light guide member 13 toward the rear surface, and of the light, goes toward the surface where the rear surface is in contact with the reflection member 12. Light is transmitted from the rear surface of the first light guide member 13 to the reflection member 1.
The light enters the second reflection surface 12a and is reflected in the front direction. Light traveling toward each groove-shaped recess 14 on the rear surface of the other first light guide member 13 is transmitted to the optical interfaces 16 a and 16 on both sides of the groove-shaped recess 14.
b.

Of the light, the optical interfaces 16a, 16a
The light incident on the light guide b at an incident angle larger than the critical angle for total reflection is totally reflected at the optical interfaces 16b and 16a, travels in the first light guide member 12, and moves toward the inside of the first light guide member 12. The light enters the rear surface and / or the opposing optical interfaces 16b and 16a, and is similarly reflected repeatedly and emitted toward the front surface of the first light guide member 13. Light incident on the optical interfaces 16a and 16b at an incident angle smaller than the total reflection critical angle (nearly perpendicular) passes through the optical interfaces 16a and 16b,
The light is refracted in the rear direction and enters the second light guide member 15.

The reason why the light incident on the second light guide member 15 is refracted toward the rear surface is that the optical interfaces 16a and 16b of the first light guide member 13 are respectively refracted by the first light guide member 13. Are inclined toward the depth direction of the groove-shaped recess 14 with respect to the normal of the reflection surface 12a of the reflection member 12 and the front surface of the first light guide member 13 at the optical interfaces 16a and 16b. This is because light is incident from the direction and the refractive index of the second light guide member 15 is smaller than the refractive index of the first light guide member 13.

The light reflected by the optical interfaces 16a and 16b and refracted toward the rear surface of the first light guide member 13 is reflected from the rear surface of the first light guide member 13 according to the refraction direction. To the reflection surface 12a and reflected in the front direction, or to the opposite optical interfaces 16b and 16a.

Light incident on the optical interfaces 16b and 16a on the opposite side is changed according to the incident angle.
The light is reflected at b, 16a and refracted in the front direction, or passes through the optical interfaces 16b, 16a and enters the second light guide member 15. Further, the light incident on the second light guide member 15 passes through the second light guide member 15, enters the reflection surface 12a of the reflection member 12, and is reflected in the front direction.

Further, the reflection surface 12a of the reflection member 12
Of the light reflected by the first light guide member 13, the reflected light of the light incident on the reflection member 12 from the rear surface between the groove-shaped recesses 14 of the first light guide member 13 travels in the first light guide member 13 in the front direction. And is emitted from the front surface. Note that, of the reflected light, the light reflected toward the optical interfaces 16a and 16b is reflected at the optical interfaces 16a and 16b, refracted toward the front, and emitted from the front of the first light guide member 13. I do.

The reflected light transmitted through the second light guide member 15 and incident on the reflection member 12 is incident on the optical interfaces 16a and 16b from the second light guide member 15 and is reflected by the optical interface. The light is refracted in the front direction at 16a and 16b, enters the first light guide member 13, passes through the inside of the first light guide member 13 toward the front direction, and exits to the front surface. In the light refracted by the optical interfaces 16a and 16b and incident on the first light guide member 13, the opposite optical interfaces 16b and 1
The light traveling toward 6a is transmitted to the opposite optical interfaces 16b and 16b.
The first light guide member 13 is reflected by the first light guide member 13 and refracted in the front direction.
Out to the front of

As shown in FIG. 1, the light emitted from the front surface of the first light guide member 13 has a divergence angle smaller than the incident angle range of the light incident on the front surface of the first light guide member 13. The emission direction is determined by the refractive indexes of the first and second light guide members 13 and 15 and the inclination angles θ1 and θ2 of the optical interfaces 16a and 16b on both sides of the groove-shaped concave portion 14.

That is, the directional reflector 11 is provided with the first
The light incident on the front surface of the light guide member 13 in a predetermined incident angle range and the light reflected by the reflection member 12 are reflected by the interface between the first light guide member 13 and the second light guide member 15. The light is refracted at certain optical interfaces 16a and 16b, and the reflected light is emitted from the front surface of the first light guide member 13 in a predetermined direction at a divergence angle smaller than the incident angle range of the incident light. Optical interfaces 16a on both sides of the concave portion 14,
The reflected light of light incident at various incident angles from the inclination direction of the optical interface 16a having a larger inclination angle with respect to the normal line of the reflection surface 12a of the reflection member 12 of the reflection member 12 is condensed in a predetermined direction and emitted. .

The direction of emission of the reflected light from the directional reflector 11 is, as described above, the direction of the first and second light guide members 1.
3, 15 and the optical interfaces 16a, 16 on both sides.
The light is emitted in the front direction of the directional reflection plate 11, that is, in the direction near the normal to the front surface of the first light guide member 13, by appropriately selecting these angles. be able to.

The directional reflector 11 shown in FIGS. 1 and 2
Is that the second light guide member 15 is an air layer having a refractive index of 1, and the refractive index of the first light guide member 13 is 1.63 ± 0.0.
5. Optical interfaces 16a, 16b on both sides of the groove-shaped recess 14
One optical interface 1 inclined in the main light incident direction
6a has an inclination angle θ1 of 30 ° ± 5 °, and the other optical interface 1
6a has an inclination angle θ2 of 20 ° ± 5 °, and the directional reflector 11 reflects reflected light of light incident at various incident angles from the inclination direction of the optical interface 16a having the larger inclination angle. The light is focused and emitted in the front direction.

The light transmitted through the inside of the first light guide member 13 toward the front surface passes through the interface between the front surface of the light guide member 13 and the outside air (air), and exits. Since the light transmitted through the light guide member 13 is incident on the interface at an angle substantially perpendicular to or near the interface, the refraction of the outgoing light at the interface is little or very slight.

The reflection type display device of the above embodiment is
The directional reflector 11, which faces the rear surface of the display panel 10 to reflect incident light from the front surface and emits the reflected light to the front surface in a predetermined direction at a divergence angle smaller than the incident angle range of the incident light. Since they are arranged, the display viewed from a predetermined direction can be made sufficiently bright.

In other words, the directional reflector 11 has the optical interface 16a having the larger inclination angle with respect to the normal line of the reflection surface 12a of the reflection member 12 among the optical interfaces 16a and 16b on both sides of the groove-shaped recess 14. Reflected light of light incident at various angles of incidence from the tilt direction is condensed in a predetermined direction and emitted. In the reflection type display device, the directional reflection plate 11 is arranged such that the tilt angle is larger. Since the inclination direction of the optical interface 16a is arranged toward the upper edge side of the screen, which is the main external light capturing direction of the display device, the light incident from the main external light capturing direction and transmitted through the display panel 10 is not reflected. The optical interface 1 having the larger inclination angle is provided on the directional reflector 11.
6a is taken in from the inclination direction, and the reflected light is emitted in a predetermined direction and enters the display panel 10 from the rear surface.

Therefore, according to this reflective display device, external light can be made to enter the display panel 11 from a predetermined direction, and reflected light with a smaller divergence angle can be emitted to the observer. The display viewed from the direction can be made sufficiently bright.

The direction of emission of the reflected light from the directional reflector 11 is determined by the first and second light guide members 1 as described above.
3, 15 and the optical interfaces 16a, 16 on both sides.
Since they are determined by the inclination angles θ1 and θ2 of b, by selecting these so as to emit light in the front direction of the directional reflector 11, the light incident on the display panel 10 from the rear surface and emitted to the front surface can be obtained. The emission direction is set to the display panel 10
The direction near the normal to the front of the display can be obtained, and a display with high front luminance can be obtained.

The directional reflection plate 1 of the first embodiment is described.
1 has a groove-shaped recess 14 provided on the rear surface of the first light guide member 13 formed in a V-shaped cross section having two side surfaces inclined in opposite directions. At least both side surfaces are inclined surfaces, and these side surfaces and the second
The optical interfaces 16a and 16b respectively reflect and transmit incident light in accordance with the incident angle.
Any cross-sectional shape may be used as long as it is a polygonal shape.

FIG. 3 is an enlarged side view of a part of a directional reflector according to a second embodiment of the present invention. The directional reflector 11 of this embodiment has a rear surface of a first light guide member 13. The groove-shaped concave portion 14 to be provided has a trapezoidal cross section having two side surfaces inclined in opposite directions and a bottom surface substantially parallel to the reflection surface 12a of the reflection member 12, and the two side surfaces and the second light guide member 15 are provided. And the optical interfaces 16a and 16
b, the interface between the bottom surface and the second light guide member 15
6c.

The directional reflector 11 of this embodiment is
The groove-shaped concave portion 14 has a trapezoidal cross section, and the interface between the bottom surface and the second light guide member 15 is a transmission surface 16c. Other configurations are the same as those of the first embodiment. Therefore, the same description is given to the drawings and the duplicate description is omitted.

According to the directional reflector 11 of this embodiment,
Not only the optical interfaces 16a and 16b on both sides of the groove-shaped recess 14 but also the bottom surface of the groove-shaped recess 14 and the second light guide member 15
The transmission surface 16c which is an interface with
Is refracted as shown by the arrow in the figure, so that the number of refracting surfaces of the light increases. Therefore, the first light guide member 13 is made of a material having a relatively small refractive index, and The light incident from the front surface of the light guide member can be emitted in a predetermined direction at a spread angle smaller than the incident angle range of the incident light.

The directional reflector 11 of this embodiment is
The incident light within a predetermined incident angle range incident on the front surface of the first light guide member 13 and the reflected light reflected by the reflective member 12 are:
The optical interface 16a, 16b on both sides of the groove-shaped recess 14 of the first light guide member 13 and the transmission surface 16c on the bottom surface of the groove-shaped recess 14 refract the reflected light of the first light guide member 13. The light is emitted from the front surface in a predetermined direction at a divergence angle smaller than the incident angle range of the incident light. The reflected light of the light incident at various incident angles from the inclination direction of the optical interface 16a having the larger inclination angle with respect to the reflected light can be collected and emitted in a predetermined direction.

In the directional reflector 11 shown in FIG. 3, the second light guide member 15 is an air layer having a refractive index of 1, and the first light guide member 13 has a refractive index of 1.49 ± 0. .05, one of the optical interfaces 16a and 16b on both sides of the groove-shaped recess 14 having an inclination angle θ1 of 30 ° ± 5 with respect to the vertical direction of the front surface of the first light guide member. °, the inclination angle θ2 of the other optical interface 16a is 20 ° ± 5 °, and the directional reflection plate 11 is incident at various incident angles from the inclination direction of the optical interface 16a having the larger inclination angle. The reflected light of the light is collected in the front direction and emitted.

The directional reflectors 11 of the first and second embodiments correspond to the respective groove-shaped recesses 14 of the first light guide member 13.
Although the second light guide member 15 provided inside is an air layer,
The light guide member 15 of the festival 2 is not limited to the air layer, and may be a transparent resin layer having a smaller refractive index than the first light guide member 13.

In this case, the directional reflection plate 11 is formed on the reflection surface 12a of the reflection member 12 by forming a plurality of second light guide members 15 made of the transparent resin layer or the like, and a refractive index is formed thereon. It is also possible to apply a method of forming a first light guide member 13 in which a portion covering the second light guide member 15 is a groove-shaped concave portion 14 by applying a transparent resin or the like having a large size.

In the first and second embodiments,
The larger angle of inclination of the optical interface was arranged on the upper edge side of the screen of the display device, and the smaller angle of inclination was arranged on the lower edge side. However, the angle of inclination of each optical interface, the first light guide member and The refractive index of the second light guide member and the dimension of the groove-shaped recess provided in the first light guide member are such that the intensity of light emitted from the display panel is slightly lower from the front of the display device. It can be appropriately set to be higher in the inclined direction. For example, an optical interface with a small inclination angle may be arranged on the upper edge side.

In the directional reflection plate 11 of each of the above embodiments, the first light guide member 13 is replaced with the flat front transparent plate 1.
3a and the rear transparent plate 13b having the groove-shaped concave portion 14 formed on one surface are bonded to each other.
The light guide member 13 may be an integrated member made of one transparent plate.

Further, the reflection type display device of the above embodiment is
Although a liquid crystal display panel is used for the display panel 10, the display panel 10 may be another electro-optical display element, a light-transmitting image printing film, or the like.

[0059]

According to the directional reflector of the present invention, the rear surface of the first light guide member having a plurality of rows of groove-shaped recesses formed in a predetermined direction on the rear surface is opposed to the reflection surface of the reflection member, A second light guide member having a smaller refractive index than that of the first light guide member is provided in each groove-shaped recess of the first light guide member, and the first light guide member and the second light guide member are provided. The interface with the optical member is an optical interface that reflects or transmits incident light on the surface in accordance with the angle of incidence, and the optical interfaces are different from each other with respect to the normal to the reflection surface of the reflection member. Since the inclined surface is inclined with the direction and the inclination angle, the first
The light incident on the front surface of the light guide member of a predetermined incident angle range and the reflected light reflected by the reflective member is refracted at the optical interface, the reflected light from the front surface of the first light guide member, The incident light can be emitted in a predetermined direction at a spread angle smaller than the incident angle range of the incident light, and high-luminance reflected light can be emitted in a predetermined direction.

The direction in which the reflected light from the directional reflector is emitted is determined by the refractive indexes of the first and second light guide members and the inclination angles of the optical interfaces on both sides, and these are appropriately selected. Thus, light can be emitted in the front direction of the reflection plate, that is, in the front direction near the normal to the front surface of the first light guide member.

In the directional reflector according to the present invention, the groove-shaped recess of the first light guide member may be a groove-shaped recess having a V-shaped cross section having two side surfaces inclined in opposite directions. The groove-shaped recess has a trapezoidal cross section having two side surfaces inclined in opposite directions and a bottom surface substantially parallel to the reflection surface of the reflection member, and an interface between the two side surfaces and the second light guide member. If the optical interface and the interface between the bottom surface and the second light guide member are respectively transmission surfaces, the number of refraction surfaces of light increases, so that the first light guide member has a material having a relatively small refractive index. The light incident from the front surface of the first light guide member can be emitted in a predetermined direction at a divergence angle smaller than the incident angle range of the incident light.

Further, the reflection type display device of the present invention reflects the incident light from the front surface, facing the rear surface of the transmission type display panel, and makes the reflected light in a predetermined direction smaller than the incident angle range of the incident light. Since the directional reflection plate that emits light to the front at the spread angle is arranged, the display viewed from a predetermined direction can be made sufficiently bright.

The direction in which the reflected light from the directional reflector is emitted is determined by the refractive indexes of the first and second light guide members and the inclination angles of the optical interfaces on both sides as described above. By selecting these so as to emit light in the front direction of the reflection plate, the emission direction of light that enters the display panel from the rear surface and emits to the front surface is set to the front direction near the normal to the front surface of the display panel. Thus, a display with high front luminance can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view of a reflective display device provided with a directional reflector according to a first embodiment of the present invention.

FIG. 2 is an enlarged side view of a part of the directional reflector.

FIG. 3 is a side view of a part of a directional reflector according to a second embodiment of the present invention.

FIG. 4 is a side view of a conventional reflective display device.

[Explanation of symbols]

 10. Display panel. DESCRIPTION OF SYMBOLS 11 ... Directional reflection plate 12 ... Reflection member 12a ... Reflection surface 13 ... First light guide member 14 ... Groove-shaped recess 15 ... Second light guide member (air layer) 16a, 16b ... Optical interface 16c ... Transmission surface

Claims (4)

[Claims] 1. A reflecting member having a flat reflecting surface and a plurality of rows of groove-shaped concave portions formed on a rear surface of the reflecting member having a flat front surface and extending in a predetermined direction on a rear surface of the reflecting member. A first light guide member disposed, and a second light guide member having a smaller refractive index than the first light guide member occupying each groove-shaped recess of the first light guide member; The groove-shaped recess of the first light guide member has at least two inclined surfaces having different inclination angles with respect to a normal line of a reflection surface of the reflection member, and a boundary surface between the inclination surface and the second reflection member. Forms an optical interface that reflects or transmits light incident on the boundary surface in accordance with the angle of incidence, and directs light incident within a predetermined incident angle range from the front surface of the first light guide member in a predetermined direction. A directional response, wherein the incident light is emitted at a spread angle smaller than the incident angle range. Plate. 2. The groove-shaped recess of the first light guide member has two inclined surfaces having different inclination angles and one bottom surface substantially parallel to the reflection surface of the reflection member. The directional reflector according to claim 1, wherein a boundary surface between a surface and the bottom surface and the second light guide member forms the optical interface. 3. A transmissive display panel, which is disposed so as to face a rear surface of the display panel, and transmits incident light from the front of the transmissive display panel in a predetermined direction from an incident angle range of the incident light. A directional reflector that emits light in front of the transmissive display panel at a small divergence angle, wherein the directional reflector has different inclination angles with respect to the normal of the reflection surface of the flat-shaped reflection member, and And a light guide member having at least two optical interfaces for refracting or reflecting the light according to an incident angle. 4. The directional reflector includes a reflecting member having a flat reflecting surface, and a plurality of rows of groove-shaped recesses having a flat front surface and extending along a predetermined direction on a rear surface. A first light guide member disposed so as to face the reflection surface of the first light guide member, and a second light guide member having a smaller refractive index than the first light guide member occupying each groove-shaped recess of the first light guide member. The groove-shaped concave portion of the first light guide member has at least two inclined surfaces having different inclination angles with respect to a normal line of a reflection surface of the reflection member. 4. The reflection type display device according to claim 3, wherein the boundary surface with the reflection member forms an optical interface that reflects or transmits light incident on the boundary surface according to the incident angle.