JPH1050124A - Lighting device and liquid crystal display device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the thickness of a planar illumination device and to reduce the thickness of a liquid crystal display device including the same. SOLUTION: An organic electroluminescence (EL) light source 10 is arranged close to a light incident end face 16 of a light guide plate 15. The organic EL light source 10 includes an organic EL element 19 composed of a transparent electrode film 12, an organic light emitting layer structure 13, and a reflective electrode film 14 sequentially laminated on a glass substrate 11. Organic EL device 1
Reference numeral 9 denotes a light guide plate 15 having a width we of about 0.1 mm and a length of 15
The width Wg of the glass substrate 11 can be reduced to about 1 mm, and the thickness of the light guide plate 15 can be reduced to about 1 mm. Light guide plate 15
The structure of the light guide plate is optimized so that light incident on the light exit surface 18 is uniformly emitted, and can be used for illumination of a liquid crystal display element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for reducing the thickness of a planar illumination device by reducing the size of a light source used in a planar illumination device for uniformly illuminating an object to be illuminated having a planar spread. .

[0002]

2. Description of the Related Art A conventional planar illumination device, particularly a planar illumination device for illuminating a direct-view type liquid crystal display device, has a fluorescent tube disposed on an end face of a transparent light guide plate made of acrylic or the like.

[0003]

However, in the conventional planar lighting device, it is technically difficult to reduce the outer diameter of the fluorescent tube to 1.5 mm or less, and it is thinner than the outer diameter of the fluorescent tube. If the light guide plate is used, the amount of light incident on the end face of the light guide plate from the fluorescent tube is reduced, so that it is difficult to reduce the thickness of the entire lighting device including the fluorescent tube to 1.5 mm or less.

Also, since the vicinity of the electrodes at both ends of the fluorescent tube does not contribute to light emission, it is necessary to make the length of the fluorescent tube longer than the length of the light-entering end face of the light guide plate. The use thereof has a problem in that the size of the planar lighting device is hindered. This problem is particularly remarkable when the planar shape of the planar illumination device is small, for example, about 20 mm × 30 mm.

The present invention solves such a problem. An electroluminescent device (hereinafter, referred to as an EL device), in particular, an organic EL device using an organic thin film as a light emitting layer structure is used as a light source. It is an object of the present invention to provide a thin planar light source that can be illuminated by a light source.

[0006]

According to a first aspect of the present invention, there is provided a light source comprising a plate-shaped light guide made of a transparent member, and an electroluminescent element disposed on at least one end face of the light guide. And characterized by the following.

According to a second aspect of the present invention, there is provided an electroluminescent device disposed in the vicinity of a plate-shaped light guide made of a transparent member and facing at least one end face of the light guide via an air layer. And a light source comprising an element.

[0008] The third lighting device of the present invention is the first lighting device of the present invention.
Alternatively, in the second lighting device, an emission optical axis of the electroluminescent element is arranged in parallel with the end face of the light guide, and a part of a transparent substrate constituting the light source including the electroluminescent element is provided. An element for deflecting the emission optical axis is formed.

A fourth lighting device according to the present invention is the first lighting device according to the first invention.
In the third to third illumination devices, the light guide plate has a light emitting side provided with an uneven shape formed by a surface substantially parallel to a surface substantially parallel to the light emitting side plane.

The fifth lighting device of the present invention is the first lighting device of the present invention.
In the fourth to fourth lighting devices, the electroluminescent element has a structure in which the organic thin film emits light by an applied electric field.

A sixth lighting device of the present invention is the first lighting device of the present invention.
In the fifth to fifth illumination devices, the light emitting surface shape of the electroluminescent element is a linear shape along a longitudinal direction of the end face of the light guide.

A seventh lighting device according to the present invention is the first lighting device according to the first invention.
The sixth to sixth lighting devices are characterized in that the electroluminescent element has a structure capable of simultaneously emitting a red wavelength, a green wavelength, and a blue wavelength.

An eighth lighting device according to the present invention is the first lighting device according to the first invention.
In the seventh to seventh lighting devices, the electroluminescent element includes at least three independent electroluminescent elements arranged in a plane, the first electroluminescent element emits light at a wavelength in a red region, and the second electroluminescent element emits light at a wavelength in a red region. The electroluminescent device emits light at a wavelength in the green region, and the third electroluminescent device emits light at a wavelength in the blue region.

The ninth lighting device of the present invention is the eighth lighting device of the present invention.
The lighting device according to any one of claims 1 to 3, wherein the first electroluminescent element, the second electroluminescent element, and the third electroluminescent element repeatedly light up sequentially.

A first liquid crystal display device according to the present invention is characterized in that the first to eighth lighting devices according to the present invention are arranged on the back of a transmissive liquid crystal display element.

According to a second liquid crystal display device of the present invention, in the first liquid crystal display device of the present invention, a half mirror is arranged between the illumination device and the transmission type liquid crystal display element. The device is turned off and the lighting device is turned on in a dark environment.

In a third liquid crystal display device according to the present invention, the ninth illuminating device according to the present invention is disposed on the back surface of a transmissive liquid crystal display device having no color filter layer, and the first electroluminescent device and the ninth lighting device are arranged. A color image is displayed by sequentially presenting a red image, a green image, and a blue image in synchronization with lighting of the second electroluminescent element and the third electroluminescent element.

A fourth liquid crystal display device according to the present invention is characterized in that the first to eighth lighting devices according to the present invention are arranged on the front surface of a reflective liquid crystal display device.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a lighting device according to the present invention will be described with reference to FIG. FIG. 1A is a cross-sectional view, and FIG. 1B is a plan view of the lighting device as viewed from a light emitting side.

An organic EL light source 10 is arranged opposite one end of a light guide plate 15 made of a transparent flat plate. The organic EL light source 10 has a transparent electrode film 12 on one surface of a glass substrate 11 which is a transparent substrate, and an organic light emitting layer structure 13 composed of an organic thin film.
And an organic EL element 19 on which the reflective electrode film 14 is laminated. Although the organic light emitting layer structure 13 constituting the organic EL element 19 is illustrated as a single layer for easy viewing, a plurality of layer structures such as an organic hole transport layer, an organic light emitting film, and an organic electron transport layer are actually used. Often composed of When a voltage is applied to the transparent electrode film 12 and the reflective electrode film 14 and an electric field is applied to the organic light emitting layer structure 13, the organic thin film layer 13 emits light, and light is emitted toward the glass substrate 11. Note that the drawing of the voltage application wiring is omitted for easy understanding of the drawing, and is similarly omitted in the following drawings.

The organic EL element has the characteristics that it can be driven at a lower voltage and has higher luminance than the inorganic EL element conventionally used as a planar light source, and is suitable as a light source for a liquid crystal display device. ing.

Light emitted through the glass substrate 11 of the organic EL light source 10 enters the light guide plate from the light incident end face 16 of the light guide plate 15, and propagates in the light guide plate while repeating total reflection. Scattering dots 17 for scattering light are formed on the back surface of the light guide plate 15, and the light reaching the scattering dots 17 is scattered and emitted from the light exit surface 18 of the light guide plate 15. By optimizing the arrangement of the scattering dots 17, light emitted from the light emitting surface 18 can be made uniform.

In order to make the intensity of light emitted from the light exit surface 18 of the light guide plate 15 uniform over the light exit surface, an organic E
The shape of the light emitting surface of the L element 19, that is, the transparent electrode film 1
2. It is effective that the light emitting layer structure including the organic light emitting layer structure 13 and the reflective electrode film 14 is formed in a stripe shape long in the longitudinal direction of the light incident end face 16 of the light guide plate.

As a configuration of the organic EL light source, a configuration as shown in a cross section in FIG. 13 can be considered. On the glass substrate 132,
An organic EL element 131 is formed in which a transparent electrode film 133, an organic light emitting layer structure 134, and a reflective electrode film 135 are sequentially laminated. The normal line of the light emitting surface of the organic EL element 131 is parallel to the incident end face of the light guide plate 139.
Light from the element does not enter the light guide plate. Accordingly, a mirror element 136 is formed on a part of the glass substrate 132 which is a component of the organic EL light source, and a metal thin film is formed on the mirror element 136 to form a reflection film 137.
Light emitted from the element 131 is deflected in the direction of the light guide plate 139 so as to be incident on the light guide plate 139.

With such a light source configuration, the thickness t of the glass substrate 132 constituting the organic EL light source 130 can be reduced.
Although the thickness is small, the width w of the glass substrate can be increased to some extent, so that the organic EL element is more organic than the configuration in which the emission optical axis of the organic EL element is orthogonal to the incident end face of the light guide plate as shown in FIG. Handling at the time of mounting the EL light source becomes easy.

It is desirable for a lighting device for illuminating an object to be displayed in color to emit white light. The structure of an organic EL device that emits white light is as follows: 1) FIG.
In the organic EL device structure as shown in (2), the same organic light-emitting film contains a dye that emits light at each wavelength of red, green, and blue. 2) Between the transparent electrode film and the reflective electrode film A red light emitting film made of organic molecules emitting red light, a green light emitting film made of organic molecules emitting green light, and a blue light emitting film made of organic molecules emitting blue light are sequentially laminated, and an electric field applied between the electrodes. 3) a structure in which these three light emitting films emit light simultaneously; 3) a structure as shown in FIG. 4, an organic EL element 32R that emits red light, an organic EL element 32G that emits green light, and a light that emits blue light. Organic EL
A structure in which the elements 32R are independently and closely arranged is conceivable.

As the structure of the light guide plate for converting the light emitted from the linear light source into the planar illumination light, in addition to the structure in which the scatterer is formed on the back surface of the transparent flat plate as shown in FIG. FIG.
The light guide plate 20 can be used in which the surface of the light exit surface 21 is provided with an irregular shape having a rectangular or slightly trapezoidal cross section as shown in FIG. The structure of such a light guide plate has already been disclosed in JP-A-6-289391 and JP-A-6-324331.

In the light guide plate 20 having such a structure, the light incident from the light incident end face 22 propagates in the light guide plate by total reflection, and reaches the side face of the convex shape 23 formed on the surface of the light output face 21. Only is taken out of the light guide plate.

Next, the difference between the configuration in which the organic EL light source is adhered to the light incident end face of the light guide plate and the configuration in which the organic EL light source is arranged on the light incident end face of the light guide plate via an air layer is as follows.
This will be described with reference to FIG. FIG. 4A is a cross-sectional view when the glass substrate 11 of the organic EL light source 10 is bonded to the light incident end face 41 of the light guide plate 40 with an optical adhesive, and FIG.
Glass substrate 11 of light source 10 and light incident end surface 41 of light guide plate 40
FIG. 4 is a cross-sectional view in the case where an air layer is interposed therebetween.

If the material of the light guide plate 40 is acrylic, the critical angle at which light propagating in the light guide plate is totally reflected is 42.
2 °. Assuming that the refractive index of the glass substrate 11 of the organic EL light source 10 is 1.51, light having a radiation angle θ1 = 40 ° emitted from the light emitting layer structure in the organic EL light source 10 is shown in FIG.
In the case of (a), the incident angle θa1 = 4 on the flat surface 42 of the light guide plate.
At 9 °, the light is totally reflected, and also in the case of FIG. 4B, the light enters the flat surface 42 of the light guide plate at an incident angle θb1 = 49 ° and is totally reflected.

On the other hand, in the organic EL light source 10, light having a radiation angle θ2 = 50 ° emitted from the light emitting layer structure is shown in FIG.
In the case (a), the incident angle θa2 = 3 on the flat surface 42 of the light guide plate.
The light enters at 9 ° and is refracted by the flat surface 42 and goes out of the light guide plate 40. In the case of FIG. 4B, since the light is totally reflected on the surface of the glass substrate 11, it does not enter the light guide plate 40.

When the organic EL light source is directly connected to the light-entering end face of the light guide plate as shown in FIG. 4A, light leaks out without being totally reflected by the light guide plate and propagated. 4 (a) and 4 (b) depending on factors such as whether the light that leaks out can be tolerated or whether the organic EL light source can be mounted with a space from the light incident end face of the light guide plate as shown in FIG. 4 (b). You can decide which arrangement to choose.

The illumination device having the above configuration can be used for illumination of a direct-view type liquid crystal display device.

FIG. 5 is a sectional view showing an example of a liquid crystal display device for illuminating a transmission type liquid crystal display element from the back. The organic EL light source 10 is arranged via an air layer so as to face the light incident end face of the light guide plate 15 having the scattering dots 17 formed on the back surface.
The liquid crystal display element 50 includes a glass substrate 52 on which a liquid crystal driving transistor and a color filter are formed and a polarizing plate 53 sandwiching a liquid crystal layer 51. Light emitted from the light exit surface 18 of the light guide plate 15 is diffused by the diffusion sheet 55, and the directivity is enhanced by the prism sheet 54 to illuminate the liquid crystal display element 50. Will be able to see. A reflection sheet 56 is disposed on the back of the light guide plate 15.

FIG. 7 shows an example of a liquid crystal display device for illuminating a transflective liquid crystal display element from the back. This is a structure in which a half mirror is formed on the liquid crystal display device shown in FIG. The half mirror layer 71 is formed on the back surface of the lower polarizing plate 72 constituting the liquid crystal display element 70. In a bright environment, the illuminating device is turned off, and ambient light 73 such as sunlight or room light entering from the front of the liquid crystal display element 70 is reflected by the half mirror layer 7.
An image displayed on the liquid crystal display element 70 after being reflected at 1 is viewed. On the other hand, when the ambient light is insufficient and ambient light reflected by the half mirror layer makes it difficult to display the image, such as at night, the illumination device, that is, the organic EL light source is turned on and half of the light emitted from the light guide plate 15 is emitted. The display is made visible by the illumination light 74 transmitted through the mirror layer 71.

In such a transflective liquid crystal display device,
Since the half mirror layer 71 is used, only a part of the incident ambient light can be used when the ambient light is reflected by the half mirror layer, and the light guide plate is also used when the lighting device is turned on. There is a problem that only a part of the light emitted from the light source can be used, and a reflective liquid crystal display device described below solves this problem.

FIG. 11 shows an example in which the illumination device of the present invention is applied to a reflection type liquid crystal display device. An illumination device is arranged on the viewer side with respect to the liquid crystal display element 113. Light guide plate 11
Numeral 0 has a structure as described in FIG. 2, and a convex shape 111 is formed on the light emitting surface of the light guide plate. Liquid crystal display element 113
Is formed on the back surface of the lower polarizing plate 117 constituting the
Are formed. In a bright environment, the organic EL light source 10 is turned off, the light enters the liquid crystal display element 113, and the diffuse reflection layer 11
The display is made visible with ambient light 73 reflected at 8. In this case, an image displayed on the liquid crystal display element is viewed through the light guide plate 110. However, if the convex shape 111 does not interfere with the pixels of the liquid crystal display element, the display image is less deteriorated. On the other hand, when the ambient light is insufficient and the display is difficult to see only with the ambient light reflected by the diffuse reflection layer such as at night, the lighting device, that is, the organic EL light source 10 is turned on.
Illumination light 120 emitted from the convex shape 111 of the light guide plate 110 and illuminating the liquid crystal display element from the front is reflected by the diffuse reflection layer so that the display can be viewed. In a liquid crystal display device having such a configuration, both the ambient light and the illumination light of the illumination device are ideally 1 light.
00% available.

The organic EL light source can be arranged not only on one end face of the light guide plate but also on two orthogonal end faces, two opposing parallel end faces, and three U-shaped end faces. .

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.

(Embodiment 1) FIG. 1 shows the configuration of a first embodiment of the lighting apparatus of the present invention. FIG. 1A is a sectional view, and FIG.
(B) is a plan view.

The organic EL element 19 includes a transparent electrode film 12 made of a transparent conductive thin film of ITO (indium tin oxide), a hole injection layer, a red light emitting layer, a green light emitting layer, and a glass substrate 11 having a thickness of 1 mm. It is formed by sequentially laminating an organic light-emitting layer structure 13 on which a blue light-emitting layer is laminated, and a reflective electrode film 14 composed of a metal thin film of MgAg.

The hole injection layer constituting the organic light emitting layer structure 13 is a triphenyldiamine derivative (TPD), the red light emitting layer is a material obtained by adding a red fluorescent dye to a quinolinol aluminum complex, and the green light emitting layer is a quinolinol aluminum As the complex and the blue light emitting layer, an oxazole complex of zinc can be used. Such an organic EL device structure is disclosed in IEICE technical report OME94-78.

The light guide plate 15 is an acrylic plate having a thickness of 1 mm, and has scattering dots 17 formed by printing a light-scattering paint in the form of dots on the back surface. The planar outer shape of the light guide plate 15 has a width W of 30 mm and a length L of 40 mm.

The shape of the organic EL element 19 is such that the width we is 0.
1 mm, the length is approximately equal to the width W of the light guide plate and approximately 30 mm, and the width wg of the glass substrate 11 is approximately equal to the thickness of the light guide plate 15 and approximately 1 mm.

When an electric field is applied to the organic EL element 19, red, green, and blue light are emitted at the same time, and a white light source is obtained. Light emitted from the organic EL light source 10 is incident on the light guide plate 15, is scattered by the scattering dots 17, exits from the light exit surface 18 of the light guide plate, and emits light from the entire light exit surface 18 of the light guide plate 15. Becomes

(Embodiment 2) FIG. 2 shows the configuration of a lighting apparatus according to a second embodiment of the present invention. FIG. 2A is a sectional view, and FIG.
(B) is a plan view.

The organic EL light source 10 is the first embodiment shown in FIG.
It has the same structure as.

The light emitting surface 21 of the light guide plate 20 is formed with a linear convex shape 23 having a rectangular cross section and extending in a direction parallel to the longitudinal direction of the organic EL element 19. The width and height of the convex shape are both 20 μm. In the figure, the cross-sectional shape of the convex shape is enlarged to make it easier to see, and the number of convex shapes is drawn to be much less than the actual one. In the light guide plate 20 having such a structure, the light incident from the light incident end face 22 propagates in the light guide plate by total reflection, and the convex shape 2 formed on the surface of the light exit surface 21.
Only the light that reaches the side surface of No. 3 is extracted out of the light guide plate.

The external dimensions of the light guide plate 20 are 1 mm, the width W is 30 mm, and the length L is 40 mm, as in the first embodiment.
It is. In order to make the light emitted from the light emitting surface 21 of the light guide plate uniform over the entire surface of the light guide plate, it is desirable that the density of the convex shapes 23 be increased as the distance from the organic EL light source 10 increases.

The light emitted from the light guide plate 20 emerges from the side surface of the convex shape 23,
The light in the direction of about ° is stronger. By making the side surface of the convex shape 23 an inclined surface instead of a vertical surface, that is, making the cross-sectional shape of the convex shape trapezoidal, the directivity of emitted light can be controlled to some extent.

In the present embodiment, a linear pattern is shown as the pattern of the convex shape 23.
It is possible to apply the pattern disclosed in Japanese Patent No. 324331 or another pattern.

(Embodiment 3) FIG. 3 shows the configuration of a third embodiment of the lighting apparatus of the present invention. FIG. 3A is a sectional view, and FIG.
(B) is a perspective view of the light source unit.

The structure of the light guide plate of this embodiment is the same as that of the light guide plate of the second embodiment described with reference to FIG.

The organic EL light source 30 includes, on a glass substrate 31, an organic EL element 32R that emits red light, an organic EL element 32G that emits green light, and an organic EL element 3 that emits blue light.
2B are arranged independently and in a plane.

The organic EL element 32R has an organic light emitting layer structure 34R that emits red light when an electric field is applied.
The organic EL element 32G has a structure in which an organic light emitting layer structure 34G that emits green light by applying an electric field is sandwiched between a transparent electrode film 33G and a reflective electrode film 35G. And the organic EL element 32
B has a structure in which an organic light emitting layer structure 34B that emits blue light by application of an electric field is sandwiched between a transparent electrode film 33B and a reflective electrode film 35B.

As the transparent electrode films 33R, 33G, 33B, an ITO transparent conductive film and reflective electrode films 35R, 35G, 35
As B, an MgAg metal thin film can be used.

The organic light emitting layer structures 34R, 34G, and 34B include a poly (N-vinylcarbazole) (PVK) light emitting layer serving as a hole transport layer and a (1,2,4-triazole derivative (TAZ) serving as an electron transport layer. ) / Aluminum complex (Alq)) can be used.
Alternatively, by adding a blue fluorescent dye, organic light emitting layer structures having different emission colors can be formed. Such an organic light emitting layer structure has already been disclosed.

Each of the organic EL elements 32R, 32G,
32B has a width of 0.1 mm, a length of 30 mm, and an interval of 0.15 mm. The area where the three organic EL elements are formed has a width of 0.4 mm and a length of 30 mm.

By applying an electric field to these three organic EL elements simultaneously, red, green and blue lights are emitted simultaneously,
It becomes a white light source.

(Embodiment 4) FIG. 13 is a sectional view of a fourth embodiment of the lighting device of the present invention. Unlike the organic EL light source used in the lighting devices described in the first to third embodiments, light emitted from the organic EL element is once deflected and then incident on the light guide plate.

An organic EL light source 130 includes an organic EL element 131 formed on a glass substrate 132 having a thickness t = 1 mm,
And a mirror element 136 that deflects light emitted from the organic EL element 131.

The organic EL element 131 is a transparent electrode film 13
3, an organic light emitting layer structure 134 that emits light of three primary colors by applying an electric field, and a reflective electrode film 135.

The mirror element 136 is composed of a plurality of inclined slopes like a Fresnel lens and a reflection film 137 made of a metal thin film deposited on the slope, and the light radiated from the organic EL element 131 is applied to the glass substrate 132. In the direction of the exit end face 138.

The organic EL light source 130 has an emission end face 138.
The light is emitted from the light guide plate 139, and the light is incident on the light guide plate by disposing the emission end surface 138 so as to face the light input end surface of the light guide plate 139.

If necessary, the organic EL of the glass substrate 132
A metal reflection film may be formed on the surface on which the element is formed.

The planar shape of the organic EL element 131 is 0.1 m.
Even if mx 30 mm, the width w of the glass substrate 132 is 2 m
m. Example 1 to Example 3
Since the width of the glass substrate of the organic EL light source of Example 1 could not be thicker than the thickness of the light guide plate and was about 1 mm, the cross-sectional area of the glass substrate was 1 mm × 1 mm. The cross-sectional area can be increased to 1 mm × 2 mm, and handling during mounting becomes easy.

(Embodiment 5) FIG. 14 is a sectional view of a fifth embodiment of the illumination device of the present invention. Organic E as in Example 4.
This is another embodiment of the configuration in which the light emitted from the L element is deflected to enter the light guide plate.

The organic EL light source 140 comprises: an organic EL element 141 formed on a glass substrate 142 having a thickness t = 1 mm;
And a curved mirror element 143 that deflects light emitted from the organic EL element 141.

The glass substrate 142 having such a curved mirror element 143 can be manufactured by molding glass using a mold having a curved surface and depositing a metal thin film to be the reflection film 144. After forming such a glass substrate, the organic EL element 141 is formed.

(Embodiment 6) FIG. 15 is a sectional view of a sixth embodiment of the lighting device of the present invention. This is another embodiment in which light emitted from the organic EL element is deflected and incident on the light guide plate as in the fourth and fifth embodiments.

The organic EL light source 150 includes: an organic EL element 151 formed on a glass substrate 152 having a thickness t = 1 mm;
And a reflection film 154 made of a metal thin film.

The reflection film 154 has the exception of the exit end face 153.
The organic EL element 151 is formed over the entire area that does not electrically affect the organic EL element 151.

The organic EL light source of this embodiment has a simple structure in which light emitted from the organic EL element 151 is reflected anyway and emitted from the emission end face 153 of the glass substrate 152.

In Embodiments 4, 5, and 6, only one organic EL device is used. However, as shown in FIG. 3, three organic EL devices for red, green, and blue are used. An element may be used.

(Embodiment 7) FIG. 5 is a sectional view of a transmission type liquid crystal display device which is a first embodiment of the liquid crystal display device of the present invention.

The organic EL light source 1 which emits white light to the light incident end face 16 of the light guide plate 15 having the scattering dots 17 formed on the back surface
0 is adhered.

The liquid crystal display element 50 includes a glass substrate 52 on which a transistor for driving liquid crystal and a color filter are formed and a polarizing plate 53 sandwiching a liquid crystal layer 51. Although elements such as a retardation film are actually used, they are omitted in the figure.

The light emitted from the light exit surface 18 of the light guide plate 15 is diffused by the diffusion sheet 55, and the directivity is enhanced by the prism sheet 54 to illuminate the liquid crystal display element 50. The displayed image can be viewed.

On the back surface of the light guide plate 15, there is disposed a reflection sheet 56 that reflects the light emitted on the back surface of the light guide plate and returns it to the liquid crystal display element side.

(Embodiment 8) FIG. 6 is a sectional view of a transmission type liquid crystal display device which is a second embodiment of the liquid crystal display device of the present invention.

As the light guide plate 20 of the illuminating device, a light guide plate having a projecting shape 23 formed on the light exit surface as described with reference to FIG. 2 is used. The organic EL light source 10 that can emit white light through an air layer is disposed opposite the light incident end face 22 of the light guide plate 20.

Light emitted from the light exit surface of the light guide plate 20 in the oblique direction with high directivity is deflected by the prism sheet 60 having a vertex angle corresponding to the directivity of the light emitted from the light guide plate, and illuminates the liquid crystal display device 50 from the back. I do.

On the back surface of the light guide plate 20, there is disposed a reflection sheet 61 for reflecting the light emitted on the back surface of the light guide plate and returning it to the liquid crystal display element side.

(Embodiment 9) FIG. 7 is a sectional view of a transflective liquid crystal display device according to a third embodiment of the present invention.

The lower polarizing plate 72 constituting the liquid crystal display element 70
Half mirror layer 7 with a very thin metal thin film deposited on the back of the mirror
1 is formed.

In a bright environment, the organic EL light source 10 is turned off, and ambient light 73 such as sunlight or room light entering from the front of the liquid crystal display element 70 is reflected by the half mirror layer 71 and displayed on the liquid crystal display element 70. See the image that is

On the other hand, when the ambient light is insufficient and ambient light reflected by the half mirror layer makes it difficult to view a display, such as at night, the organic EL light source 10 that emits white light is turned on and emitted from the light guide plate 15. The display is made visible by the illumination light 74 transmitted through the half mirror layer 71 among the light.

(Embodiment 10) FIG. 8 is a sectional view of a transflective liquid crystal display device according to a fourth embodiment of the present invention.

As the light guide plate 20 of the illuminating device, a light guide plate having a projecting shape 23 formed on the light exit surface as described with reference to FIG. 2 is used. The organic EL light source 10 that can emit white light through an air layer is disposed opposite the light incident end face 22 of the light guide plate 20.

As in the tenth embodiment, the surroundings are dark and the ambient light 7
The organic EL element 19 is turned on when the display is difficult to see with only 3.

(Embodiment 11) FIG. 9 is a sectional view of a transmission type liquid crystal display device which is a fifth embodiment of the liquid crystal display device of the present invention.

The organic EL light source 30 includes organic EL elements 32R, 32G, 32B formed side by side on a glass substrate 31.
It has. An organic EL element 32R that emits red light, an organic EL element 32G that emits green light, and an organic EL element 32B that emits blue light are formed in a stripe shape as in the structure shown in FIG.

The three organic EL elements 32R, 32G, 32
By causing B to emit light simultaneously, the transmissive liquid crystal display element can be illuminated with white light from the back.

(Embodiment 12) In a sixth embodiment of the liquid crystal display device of the present invention, a color filter is removed from the liquid crystal display element 50 in the liquid crystal display device of Embodiment 11 shown in FIG. The liquid crystal display device displays the color image by lighting the EL elements 32R, 32G, and 32B sequentially instead of simultaneously.

The three organic EL elements 32R, 32G, 32
B is sequentially turned on as shown in FIG. 10, and one color image is displayed in one cycle T.

Since the liquid crystal display device of this embodiment does not require a color filter, the resolution can be improved three times as compared with a liquid crystal display device in which color filters are arranged in correspondence with each pixel.

An organic EL element has a width of 0.1 mm and a length of 30 with respect to a liquid crystal display element having a screen size of 30 mm × 40 mm.
If the blinking cannot be performed at high speed due to the capacity of the organic EL element, the stripe-shaped organic EL element may be divided and driven.

(Embodiment 13) FIG. 1 is a sectional view of a reflection type liquid crystal display device which is a seventh embodiment of the liquid crystal display device of the present invention.
It is shown in FIG.

The lower polarizing plate 1 constituting the liquid crystal display element 113
17, a diffuse reflection layer 118 is formed.

An illumination device is arranged on the viewer side with respect to the liquid crystal display element 113.

The light guide plate 110 has the structure as described with reference to FIG. 2, and has a convex shape 111 formed on the light exit surface of the light guide plate.

In a bright environment, the organic EL element 19 is turned off, and the display is made visible by the ambient light 73 incident on the liquid crystal display element 113 from the front and reflected by the diffuse reflection layer 118. In this case, an image displayed on the liquid crystal display element is viewed through the light guide plate 110. However, if the interval between the convex shapes 111 does not interfere with the pixels of the liquid crystal display element, the display image is less deteriorated.

On the other hand, when the ambient light is insufficient and ambient light reflected by the diffuse reflection layer makes it difficult to display a display, such as at night, the organic EL element 19 that emits white light is turned on and emitted from the light guide plate 110. The illuminating light 120 is diffused to
To make the display visible. In the liquid crystal display device having such a configuration, 100% of the ambient light and the illumination light of the illumination device can be ideally used.

The arrangement of the illuminating device on the viewer side of the liquid crystal display device means that the liquid crystal display element is disposed at least by the thickness of the light guide plate from the front of the display device to the back even though the light guide plate is transparent. That is, there is a possibility that the display becomes difficult to see especially when viewed from an oblique direction. From this point, it is better that the thickness of the light guide plate is thinner. In the present invention, a stripe-shaped organic EL element is used as a light source. Can be reduced to about 1 mm.

(Embodiment 14) FIG. 1 is a sectional view of a reflection type liquid crystal display device according to an eighth embodiment of the present invention.
It is shown in FIG.

The basic structure is the same as that of the embodiment 13 shown in FIG. 11, except that the organic EL light source 30 emits three stripes of organic EL light emitting in red, green and blue, respectively.
It is composed of L elements 32R, 32G, 32B.

The embodiments of the illumination device and the liquid crystal display device according to the present invention have been described above. For example, FIG. 13, FIG.
There are various ways of combining the organic EL element with the light guide and the liquid crystal display element, for example, the illumination apparatus using the organic EL light source having the structure of No. 5 can be used as the illumination apparatus of the liquid crystal display device described in the above embodiment. Can be considered, and the present invention is not limited to the configuration of the above embodiment.

When white light is not required for the illuminating device, a configuration in which all three primary color light emitting elements are not provided, such as providing only red and blue light emitting elements in the light source, can be considered.

[0109]

The lighting device of the present invention uses an organic EL element, particularly a linear organic EL element, as a light source, introduces its radiated light into the light guide plate from the end face of the light guide plate, and generates a planar light from the light exit surface of the light guide plate. 1 m, which could not be realized with a conventional light guide plate lighting device using a fluorescent tube as a light source.
It is possible to realize a lighting device that emits light in a planar shape having a thickness of not more than m, and has the effect that the entire liquid crystal display device can be made thinner.

Further, by utilizing the effect of forming a light guide plate type planar illumination device having a thickness of 1 mm or less, an illumination device of one form of the illumination device of the present invention is arranged on the observer side of the reflection type liquid crystal display element. By doing so, there is an effect that a reflection-type liquid crystal display device having high light use efficiency and excellent visibility can be formed both when the lighting device is turned on and when it is not turned on.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of a lighting device according to the present invention, in which (a) is a cross-sectional view and (b) is a plan view.

FIGS. 2A and 2B are diagrams showing a configuration of a second embodiment of the lighting device of the present invention, wherein FIG. 2A is a cross-sectional view and FIG.

FIGS. 3A and 3B are diagrams showing the configuration of a third embodiment of the lighting device of the present invention, wherein FIG. 3A is a cross-sectional view and FIG.

FIG. 4 is a cross-sectional view illustrating an arrangement of a light source with respect to a light guide plate end surface in the lighting device of the present invention.

FIG. 5 is a sectional view of a transmission type liquid crystal display device which is a first embodiment of the liquid crystal display device of the present invention.

FIG. 6 is a sectional view of a transmission type liquid crystal display device which is a second embodiment of the liquid crystal display device of the present invention.

FIG. 7 is a sectional view of a transflective liquid crystal display device according to a third embodiment of the liquid crystal display device of the present invention.

FIG. 8 is a sectional view of a transflective liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 9 is a sectional view of a transmission type liquid crystal display device which is a fifth embodiment of the liquid crystal display device of the present invention.

FIG. 10 is a diagram showing timing for turning on three light sources in a sixth embodiment of the liquid crystal display device of the present invention.

FIG. 11 is a sectional view of a reflection type liquid crystal display device which is a seventh embodiment of the liquid crystal display device of the present invention.

FIG. 12 is a sectional view of a reflection type liquid crystal display device which is an eighth embodiment of the liquid crystal display device of the present invention.

FIG. 13 is a sectional view of a fourth embodiment of the illumination device of the present invention.

FIG. 14 is a sectional view of a fifth embodiment of the lighting device of the present invention.

FIG. 15 is a sectional view of a lighting device according to a sixth embodiment of the present invention.

[Explanation of symbols]

 10, 30, 130, 140, 150 Organic EL light source 11, 31, 132, 142, 152 Glass substrate 12, 133 Transparent electrode film 13, 134 Organic light emitting layer structure 14, 135 Reflective electrode film 15, 20, 40, 110, 139 Light guide plate 16, 22, 41 Light incident end face 17 Scattering dot 18, 21, Light emitting surface 19, 131, 141, 151 Organic EL element 23, 111 Convex shape 32R, 32G, 32B Organic EL element 33R, 33G, 33B Transparent electrode film 34R, 34G, 34B Organic light emitting layer structure 35R, 35G, 35B Reflective electrode film 42, 112 Flat surface 50, 70, 113 Liquid crystal display element 51, 114 Liquid crystal layer 52, 115 Glass substrate 53, 116 Polarizing plate 54, 60 Prism sheet 55 Diffusion sheet 56, 61 Reflection sheet 71, 117 Half mirror layer 2 lower polarizing plate 73 surrounding light 74,80,120 illumination light 118 diffuse reflection layer 136 mirror elements 138,153 emitting facet 137, 144, 154 reflective film 143 curved mirror elements

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location H05B 33/00 H05B 33/00

Claims (13)

[Claims] 1. A lighting device comprising: a plate-shaped light guide made of a transparent member; and a light source made of an electroluminescent element disposed on at least one end face of the light guide. 2. A light guide comprising: a plate-shaped light guide made of a transparent member; and a light source made of an electroluminescent element disposed close to an at least one end face of the light guide via an air layer. A lighting device, comprising: 3. An emission optical axis of the electroluminescent element is disposed parallel to the end face of the light guide, and the emission optical axis is provided on a part of a transparent substrate constituting the light source composed of the electroluminescent element. The lighting device according to claim 1, wherein an element for deflecting light is formed. 4. The light guide plate according to claim 1, wherein a light emitting side surface of the light guide plate is provided with an uneven shape formed by a surface substantially parallel to the light emitting side surface and a surface substantially perpendicular to the light emitting side surface. Lighting equipment. 5. The lighting device according to claim 1, wherein the electroluminescent element has a structure in which an organic thin film emits light by an applied electric field. 6. The lighting device according to claim 1, wherein a shape of a light emitting surface of the electroluminescent element is a linear shape along a longitudinal direction of the end face of the light guide. 7. The electroluminescent device according to claim 1, wherein the electroluminescent device comprises a red region, a green region,
7. The lighting device according to claim 1, wherein the lighting device has a structure capable of simultaneously emitting light of wavelengths in the blue and blue regions. 8. The electroluminescent device comprises at least three independent electroluminescent devices arranged in a plane, the first electroluminescent device emits light at a wavelength in the red region, and the second electroluminescent device emits light at a wavelength in the red region.
The lighting device according to claim 1, wherein the electroluminescent device emits light at a wavelength in a green region, and the third electroluminescent device emits light at a wavelength in a blue region. 9. The lighting device according to claim 8, wherein the first electroluminescent element, the second electroluminescent element, and the third electroluminescent element repeatedly light up sequentially. 10. A liquid crystal display device, wherein the lighting device according to claim 1 is arranged on a rear surface of a transmissive liquid crystal display element. 11. A method according to claim 11, further comprising disposing a half mirror between said lighting device and said transmissive liquid crystal display element to turn off said lighting device in a bright environment and to turn on said lighting device in a dark environment. Item 11. The liquid crystal display device according to item 10. 12. The lighting device according to claim 9, wherein the lighting device according to claim 9 is disposed on a rear surface of a transmission type liquid crystal display device having no color filter layer, wherein the first electroluminescent device, the second electroluminescent device, and the third electroluminescent device are arranged. A liquid crystal display device displaying a red image, a green image, and a blue image sequentially in synchronization with lighting of the electroluminescent element. 13. A liquid crystal display device, wherein the lighting device according to claim 1 is arranged on a front surface of a reflection type liquid crystal display device.