JP2002150822A - Lighting device utilizing outside light, and display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device which uniformly and brilliantly lights a display surface by efficiently utilizing the light from outside, and to provide a display device utilizing above lighting device. SOLUTION: The lighting device comprises a light collecting area 10 collecting outer light 30, a light guiding area 11 guiding the collected light, and a lighting area 12 making the collected light go out. The light collecting area has the first transparent plate 1 and a reflection deflection element 3 formed at the backside of the first transparent plate 1. The reflection deflection element 3 reflects and deflects the light of incidence getting in from the front surface of the first transparent plate 1, and makes the light get in the front surface of the first transparent plate 1 with an angle exceeding the critical angle. The lighting area is composed of the second transparent plate 1 guiding the light guided from the light guiding area and a deflection element 8 arranged at the front surface or the back surface of the second transparent plate, and the deflection element makes the light guided by the total reflection in the second transparent plate get out from the front surface or the back surface of the second transparent plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device using external light and a display device using the illuminating device. The present invention relates to a lighting device used and a display device using the lighting device.

[0002]

2. Description of the Related Art A typical type of display device that illuminates using external light is a reflection type liquid crystal display device. The reflection type liquid crystal display device is used for a display device such as a notebook PC, a portable information terminal, and a mobile phone, but it is difficult to observe or display brightly depending on the incident direction of external light.

[0003] On the other hand, some of such display devices of portable equipment use a lighting device using a light source and a light guide plate or a lighting device including an EL light source. There is a problem in that these portable devices cannot be used for a long time because of their necessity.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a lighting device capable of efficiently taking in external light to uniformly illuminate a screen. An object of the present invention is to provide a device and a display device using the same.

[0005]

According to the present invention, there is provided a lighting device utilizing external light according to the present invention, wherein the external light is used as illumination light. A light-guiding region, a light-guiding region for guiding the light collected by the light-gathering region, and an illumination region for emitting the light guided by the light-guiding region. And a reflection / deflection element provided on the back surface of the first transparent plate, wherein the reflection / deflection element reflects and deflects at least a part of the light incident from the front surface of the first transparent plate to produce the first light. The light is incident on the front surface of the transparent plate at an angle exceeding the critical angle, and the illumination region is a second transparent plate that guides light guided from the light guide region, and the front surface of the second transparent plate or A deflecting element provided on the back surface, wherein the deflecting element is It is characterized in that the light is guided by total internal reflection is intended to emit from the front or back surface of the second transparent plate with a transparent plate in.

In this case, the reflection / deflection element in the daylighting area is provided on the transmission type volume hologram and the back surface thereof, regardless of whether it is composed of an inclined reflection surface or a blazed mirror surface or a reflection type volume hologram. It may be composed of a reflective layer, or may be composed of a relief hologram and a reflective layer provided on a relief surface on the back surface.

The light guide region may include a third transparent plate integrated with the first transparent plate and the second transparent plate, or may include an optical fiber or a bundle of optical fibers. Good.

The illuminating device using external light according to the present invention displays a display pattern on a screen by illuminating from the front of the display surface, and displays a display pattern on the screen by illuminating from behind the display surface. It can be used for any of the display devices.

[0009] In this case, in the configuration in which illumination is performed from behind the display surface, in the illumination area of the illumination device, if a deflecting element is provided on the front surface of the second transparent plate, the deflecting element is provided on the back surface of the second transparent plate. When the deflecting element is provided on the back surface, a reflective layer may be provided on the back surface of the deflecting element.

[0010] In the present invention, there is provided a daylighting region for picking up external light, a light guide region for guiding light picked up in the daylighting region,
An illumination area for emitting the light guided by the light guide area, and the lighting area includes a first transparent plate and a reflection / deflection element provided on the back surface of the first transparent plate. The deflecting element reflects and deflects at least a part of the light incident from the front surface of the first transparent plate and makes the light incident on the front surface of the first transparent plate at an angle exceeding a critical angle. And a deflecting element provided on the front or back surface of the second transparent plate, and the deflecting element is guided by total reflection in the second transparent plate. Since the light to be emitted is emitted from the front or back surface of the second transparent plate, external light can be efficiently taken in and uniformly illuminated, and power can be consumed as a lighting device for display of a portable device. It can be brightly illuminated without the need.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a lighting device using external light and a display device using the lighting device according to the present invention will be described based on embodiments.

FIG. 1 is a schematic sectional view showing an illuminating device according to an embodiment of the present invention and a transmissive liquid crystal display device incorporating the illuminating device. The illuminating device is a transparent plate made of a transparent material such as plastic. The transparent plate-like body 1 includes a body 1, and is composed of three parts 10, 11 and 12. The part 10 is a lighting area, the part 11 is a light guide area, and the part 12 is an illumination area. The transparent plate 1 is divided into three parts, and the light guide area 11 connects the lighting area 10 and the illumination area 12. The front surface of the transparent plate-like body 1 is composed of a common plane 2, and the back surface thereof is a lighting region 10 and a light guide region 1
1. The illumination area 12 has a different shape. The back surface of the daylighting area 10 is formed by connecting a band-shaped inclined surface 3 as shown in a sawtooth cross section, and the outer surface thereof is provided with a mirror coat 4 to form a blazed mirror surface. The direction of the inclination of the inclined surface 3 is such that the distance between the inclined surface 3 and the surface of the transparent plate 1 increases toward the light guide region 11 as shown in the figure. The back surfaces of the light guide region 11 and the illumination region 12 are formed by a common plane 5. The transmission hologram 8 is closely or adhered to the plane 2 of the surface of the illumination area 12.

The transmission type hologram 8 is disclosed in Japanese Patent Application Laid-Open No. 11-109338 (Japanese Patent Application No. 9-26949) by the present applicant.
Similarly to the transmission hologram of No. 5), light guided inside the transparent plate 1 in the illumination area 12 and incident on the transmission hologram 8 at a predetermined angle equal to or greater than the critical angle is applied to the surface of the transparent plate 1. It has the property of diffracting out as diffracted light 32.
The diffraction efficiency of the transmission hologram 8 is set lower on the average closer to the light guide region 11 and higher as the distance from the light guide region 11 increases. One way to provide such a distribution of diffraction efficiency is to provide a distribution so that the desired diffraction efficiency can be obtained for the light intensity of the object light and the reference light at the time of hologram imaging. Alternatively, the transmission hologram 8 may be an aggregate of fine holograms patterned in a halftone dot pattern, and the area ratio of the fine hologram may be reduced as the distance from the light guide region 11 increases and increased as the distance from the light guide region 11 increases. do it. For details, see JP-A-11-109338.

With such a configuration, the lighting area 10
When the external light 30 is incident on the surface, the light is refracted by the flat surface 2 of the surface and enters the transparent plate-shaped body 1, reflected by the inclined surface 3 on the back surface, and again incident on the flat surface 2 of the lighting area 10. At this time, since the inclined surface 3 on the back surface is inclined such that the distance between the inclined surface 3 and the surface of the transparent plate-shaped body 1 increases toward the light guide region 11 as described above, the incident light incident on the plane 2 from inside is The angle is larger than the angle of refraction (the inclination of the inclined surface 3 is θ
Then, the incident angle becomes 2θ larger than the refraction angle. ). Since the external light 30 has a component that enters from a certain spread angle, the external light 30 refracted from the surface of the daylighting region 10 is reflected by the inclined surface 3 and reenters the surface from the inside. When there is a component whose incident angle is equal to or greater than the critical angle causing total reflection, and the component is reflected again by the inclined surface 3 on the back surface, the incident angle incident from the inside on the surface of the lighting area 10 becomes larger, and total reflection occurs. Is done. Therefore, the external light component totally reflected on the surface of the lighting area 10 becomes light 31 guided in the transparent plate-like body 1, enters the light guide area 11 adjacent to the lighting area 10, and forms the light on the front and back surfaces. Planes 2 and 5
The light travels while repeating total reflection, and enters the illumination area 12.

Since the transmission hologram 8 closely or adhered to the surface of the illumination area 12 has the above-described configuration, light is guided from the light guide area 11 while repeating total reflection in the transparent plate 1. During this time, the light 31 is diffracted by the transmission hologram 8 and becomes the diffracted light 32 as the illumination area 12.
Is diffracted forward, and becomes illumination light for uniformly illuminating the entire surface of the transmissive liquid crystal display element 20 closely contacted with the transmissive hologram 8 from the back side.

Here, the transmission type liquid crystal display element 20 is, for example, a TN liquid crystal display element, and a liquid crystal layer 23 is sandwiched between transparent substrates 21 and 22 and sealed. This transparent substrate 2
A transparent pixel electrode is provided on the inner surface of one of the liquid crystal layers 23 on the side of the liquid crystal layer 1, 22, and a transparent counter electrode is provided on the other, and an alignment film or the like is provided thereon. The polarizing plates 24 and 25 are arranged in a state of parallel Nicols or orthogonal Nicols. In the case of color display, a color filter is arranged on the transparent counter electrode.

With such a configuration, by combining the above-described lighting device 15 of the present invention, which includes the daylighting region 10, the light-guiding region 11, and the lighting region 12, with the transmissive liquid crystal display element 20 as a backlight source, In addition, it is possible to configure a transmissive liquid crystal display device that can efficiently take in external light to uniformly illuminate the screen and illuminate the screen, and that can perform bright display.

In the above embodiment, the light guide region 1
Mirror coat may be applied to the planes 2 and 5 on both sides of 1.
Further, a mirror coat may be applied to the flat surface 5 on the back surface of the illumination area 12.

Further, instead of the transmission hologram 8 being adhered or adhered to the surface of the illumination area 12, a reflection hologram is adhered or adhered to the back surface thereof, and the total reflection is repeated within the transparent plate 1. The light 31 guided from the light guide region 11 may be diffracted by a reflection hologram during that time and may be emitted to the front of the light guide region 11 to be used as illumination light. This reflection hologram is disclosed in
Similarly to the reflection hologram of No. 9338, the illumination area 12
And has the property of diffracting light guided inside the transparent plate-shaped object 1 and incident on the reflection hologram at a predetermined angle equal to or greater than the critical angle as diffracted light 32 outside the surface of the transparent plate-shaped object 1. For details, see JP-A-11-109338.

Further, when a reflection type hologram is adhered to or adhered to the back surface of the illumination area 12 having the configuration shown in FIG. 1 or a modification thereof, the reflection type hologram provided on the back surface 5 of the illumination area 12 or the plane 5 is provided. A mirror coat may be applied to the mirror to reflect external light transmitted through the transmissive liquid crystal display element 20 and function as a reflective liquid crystal display by external light illumination. Light illumination and illumination by the external light 30 taken in from the daylighting area 10 may be used in combination.

Next, FIG. 2 is a schematic cross-sectional view when the same illuminating device as that of FIG. 1 is incorporated in a reflection type liquid crystal display device. Only the difference from FIG. That is, the transmission hologram 8 is closely attached or adhered to the flat surface 5 on the back surface of the illumination area 12.

The reflection type liquid crystal display element 20 'is closely attached to the transmission type hologram 8.

The reflection type liquid crystal display element 20 'is, for example, TN
This is a liquid crystal display element, in which a liquid crystal layer 23 is sandwiched and sealed between transparent substrates 21 and 22. This transparent substrate 21, 2
2, a transparent pixel electrode is provided on the inner surface of one of the liquid crystal layers 23, a transparent counter electrode is provided on the other, and an alignment film or the like is provided thereon. The plates 24 and 25 are arranged in parallel Nicols or orthogonal Nicols. Further, a reflection layer 26 is provided on the back surface of the polarizing plate 24 on the back surface side. In the case of color display, a color filter is arranged on the transparent counter electrode.

With such a configuration, in this case,
Since the transmission hologram 8 is adhered or adhered to the back surface of the illumination area 12, the light 31 guided from the light guide area 11 while repeating total reflection in the transparent plate 1 is transmitted by the transmission hologram 8 during that time. The light is diffracted and diffracted behind the illumination area 12 as the diffracted light 32, and becomes illumination light for uniformly illuminating the entire surface of the reflective liquid crystal display element 20 ′ closely contacted with the transmission hologram 8 from the front side. The diffracted light 32
Is reflected by the reflective layer 26 on the rear surface of the reflective liquid crystal display element 20 ′ according to the display state of the reflective liquid crystal display element 20 ′.
The light exits from 0 'to the front side, passes through the transmission type hologram 8 and the transparent plate 1 disposed in front of it, and becomes display light 33. The external light is efficiently taken in, and the screen can be illuminated uniformly brightly and bright. A reflective liquid crystal display device capable of displaying is obtained. In this case, the lighting device 15 of the present invention functions as a front light source.

In the case of this example, the planes 2 and 5 on both sides of the light guide area 11 may be mirror-coated.
The mirror coat cannot be applied to the plane 2 of the surface 2.

In the case of FIG. 2, as in the case of FIG. 1, instead of the transmission hologram 8 on the back surface of the illumination area 12, a reflection hologram is adhered or adhered to the surface thereof to form a transparent plate. The light 31 guided from the light guide region 11 may be diffracted by the reflection hologram during this period while repeating total reflection within the body 1 and output as diffracted light 32 behind the light guide region 11.

By the way, in FIGS. 1 and 2, an illumination light source 7 is arranged so as to face the end 6 of the transparent plate 1 on the side of the daylighting area 10, and this illumination is used when the external light is dark. The light source 7 is turned on, and the illumination light from the light source 7 is made to enter the transparent plate 1 from the end 6 and is guided into the light guide region 11 across the daylighting region 10 in the same manner as when using external light. The diffracted light 32 is diffracted forward or backward of the illumination area 12 so that the transmissive liquid crystal display element 20 or the reflective liquid crystal display element 2
0 'may be uniformly illuminated.

As a reflection / deflection element provided on the back surface of the lighting area 10 for reflecting and deflecting the direction of incident light to cause total reflection, an inclined reflection surface or a blazed mirror surface as shown in FIGS. Instead of 3, a reflection type hologram, a transmission type hologram provided with a reflection layer, a relief hologram provided with a reflection layer, or the like may be used. FIG. 3 is a schematic sectional view of the daylighting region 10 in those cases.

FIG. 3A shows that the back surface of the lighting area 10 is a plane that is an extension of the plane 5, and that the reflection type volume hologram 4
1 and a reflection type volume hologram 41
Is reflected and diffracted so that the external light 30 within a predetermined angle range, which is refracted on the surface of the daylighting region 10 and enters the transparent plate 1, has an angle equal to or greater than the critical angle at which total reflection occurs in the transparent plate 1. It is created to have diffraction characteristics that Therefore, in the external light 30 that has been refracted from the surface of the lighting area 10 and entered,
The light is reflected and diffracted by the reflection type volume hologram 41, enters the transparent plate-shaped body 1 again from the inside thereof at an angle of incidence that is equal to or greater than the critical angle, is totally reflected, re-enters the reflection type volume hologram 41 on the back side, and so on. The light 31 that is diffracted into the light or totally reflected at the interface of the reflection type volume hologram 41 with the air is present in the transparent plate-shaped body 1 in the daylighting region 10, and FIG. As in the case of FIG. 2, the light enters the light guide region 11 adjacent to the daylighting region 10, proceeds while repeating total reflection between the front and rear planes 2 and 5, and enters the illumination region 12.

FIG. 3B shows a rear surface of the lighting area 10 as an extension of the plane 5 and a transmission volume hologram 4 on the surface.
This is an example in which a reflective layer 43 is provided on the back surface of the reflective hologram 2 and has the same reflection and diffraction characteristics as the reflective volume hologram 41 of FIG. 3A, and the operation is the same. Further, FIG. 3C shows a case where the back surface of the daylighting region 10 is a plane extending from the flat surface 5 and a relief hologram 44 is provided on the surface and a reflection layer 45 is provided on the relief surface on the back surface. This is an example in which a reflection-diffraction characteristic similar to that of the mold volume hologram 41 is attached, and the operation is the same.

In the case of FIGS. 1 and 2, the inclined surface 3 provided on the back surface of the daylighting area 10 may be made one, so that the cross section of the transparent plate 1 in the daylighting area 10 becomes wedge-shaped.

By the way, in the case of the lighting device 15 of the present invention as shown in FIGS.
Since the lighting device 5 is used as a lighting device for a portable display device such as a notebook PC, a portable information terminal, or a mobile phone, the lighting area 10 may be protruded, and the size may be increased. Therefore, the light guide region 11 may be configured by an optical fiber or an optical fiber bundle, and the light collection region 10 and the light guide region 11 may be configured to be foldable. In this case, the lighting device 15 is not composed of the single transparent plate 1, but the lighting region 10, the light guide region 11, and the lighting region 1.
2 need to be composed of different transparent bodies and connected to each other.

The lighting device using external light and the display device using the lighting device of the present invention have been described based on the embodiments. However, the present invention is not limited to these embodiments, and various modifications are possible. It is.

[0034]

As is clear from the above description, according to the lighting device using external light and the display device using the lighting device of the present invention, the light is collected in the lighting region for collecting the external light and the lighting region. And a lighting area for emitting light guided by the light guiding area. The lighting area is provided on a first transparent plate and a back surface of the first transparent plate. Reflective deflecting element, the reflective deflecting element being the first
At least a part of the light incident from the front surface of the transparent plate is reflected and deflected to be incident on the front surface of the first transparent plate at an angle exceeding the critical angle, and the illumination region is guided from the light guide region. A second transparent plate that guides light; and a deflecting element provided on the front surface or the back surface of the second transparent plate. The deflecting element transmits light guided by total reflection in the second transparent plate. (2) Since the light is emitted from the front or back surface of the transparent plate, external light can be efficiently taken in and uniformly illuminated, and bright illumination without consuming power as a display illuminating device for a portable device. It is possible.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a lighting device according to an embodiment of the present invention and a transmission type liquid crystal display device incorporating the lighting device.

FIG. 2 is a schematic cross-sectional view when the same lighting device as that of FIG. 1 is incorporated in a reflective liquid crystal display device.

FIG. 3 is a schematic cross-sectional view of a lighting area showing a modified example of a reflective deflecting element provided in the lighting area.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Transparent plate 2 ... Plane of the transparent plate surface 3 ... Incline 4 ... Mirror coat 5 ... Plane of the back of a transparent plate 7 ... Illumination light source 8 ... Transmission hologram 10 ... Lighting area 11 ... Light guide area DESCRIPTION OF SYMBOLS 12 ... Illumination area 15 ... Illumination device 20 ... Transmissive liquid crystal display element 20 '... Reflection type liquid crystal display element 21, 22 ... Transparent substrate 23 ... Liquid crystal layer 24, 25 ... Polarizing plate 26 ... Reflective layer 30 ... External light 31 ... Conduction Light light 32 ... Diffraction light 33 ... Display light 41 ... Reflection type volume hologram 42 ... Transmission type volume hologram 43 ... Reflection layer 44 ... Relief type hologram 45 ... Reflection layer

Claims (10)

[Claims] 1. A lighting device that collects external light and uses it as illumination light, wherein the lighting device includes: a lighting region for collecting external light; a light guiding region for guiding light collected in the lighting region; An illumination area for emitting light guided by the light guide area, wherein the lighting area includes a first transparent plate and a first transparent plate.
A reflective deflecting element provided on a back surface of the transparent plate, wherein the reflective deflecting device reflects and deflects at least a part of light incident from the front surface of the first transparent plate to the front surface of the first transparent plate. It is incident at an angle exceeding the critical angle,
The illumination region includes a second transparent plate that guides light guided from the light guide region, and a deflecting element provided on a front surface or a back surface of the second transparent plate. 2 the light guided by total reflection in the transparent plate
An illumination device using external light, wherein the illumination device emits light from a front surface or a back surface of a transparent plate. 2. The illumination device using external light according to claim 1, wherein the reflection / deflection element in the daylighting area comprises an inclined reflection surface or a blazed mirror surface. 3. The reflection deflecting element in the daylighting area comprises a reflection type volume hologram.
A lighting device using the external light described in the above. 4. The illumination device using external light according to claim 1, wherein the reflection / deflection element in the daylighting area comprises a transmission type volume hologram and a reflection layer provided on a back surface thereof. 5. The illumination device according to claim 1, wherein the reflection / deflection element in the daylighting region comprises a relief hologram and a reflection layer provided on a relief surface on a back surface thereof. 6. The light guide region according to claim 1, wherein the light guide region includes a third transparent plate integrated with the first transparent plate and the second transparent plate. Lighting device using external light. 7. The illuminating device using external light according to claim 1, wherein the light guide region is formed of an optical fiber or a bundle of optical fibers. 8. A display device for displaying a display pattern on a screen by illuminating from the front of a display surface, wherein the illuminating device using external light according to claim 1 is used as the illuminating device. A display device, which is used. 9. A display device for displaying a display pattern on a screen by illuminating from behind a display surface, wherein the illuminating device using external light according to claim 1 is used as the illuminating device. A display device, which is used. 10. When the deflecting element is provided on the front surface of the second transparent plate in the illumination area of the illuminating device, the deflecting element is provided on the back surface of the second transparent plate and on the back surface of the second transparent plate. 10. The display device according to claim 9, wherein a reflection layer is provided on a back surface of the deflection element.