JP3900567B2 - Illumination device and liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lighting device and a liquid crystal display device having a lighting function.
[0002]
[Prior art]
As shown in FIG. 8A, the conventional surface illumination device has the illumination device 101 disposed on the back surface of the object to be illuminated such as the liquid crystal display panel 102, and normally the illumination is always on. Further, as shown in FIG. 8B, a liquid crystal display device having a reflection function has a reflector 103 disposed on the back surface of the liquid crystal display panel 102 or the like, and is used by illumination with external light. In order to properly use reflection when the outside is bright and use backlight illumination when it is dark, a transflective plate 104 and an illumination device 101 are arranged on the back surface of the liquid crystal display panel 102 or the like as shown in FIG. It was. (For example, JP-A-57-042771, JP-A-57-054926, JP-A-58-095780, etc.).
[0003]
[Problems to be solved by the invention]
However, a conventional liquid crystal display device or the like having only an illumination function has a problem that it consumes a large amount of power because the light source is always turned on, and cannot be used for a long time, for example, as illumination for portable equipment. Further, a conventional liquid crystal display device having only a reflection function has a problem that it cannot be used in a dark place where the contrast is low. Furthermore, when a transflective plate and a lighting device are used, the problem that the display is dark both when used for reflection and when used for backlighting inevitably occurs. There is no actual situation.
[0004]
The present invention solves such problems, and an object of the present invention is to provide an illuminating device or a liquid crystal display device that can illuminate without lowering the reflection function.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the lighting device of the present invention is
(1) An illuminating device disposed on an observer side of an object to be illuminated, the transparent electrode layer, a net-like light emitting layer, and the light emitting layer on a surface of the transparent flat plate on the observer side An electroluminescent element is formed by sequentially forming a net-like metal thin film electrode layer that substantially matches, and a transparent substrate or a transparent sheet is placed between the net-like metal thin film electrode layer and the transparent flat plate on the viewer side. It arrange | positions through an air layer, It is characterized by the above-mentioned.
[0006]
(2) An illuminating device disposed on the observer side of the object to be illuminated, the transparent electrode layer, the net-like light emitting layer, and the light emitting layer on the surface of the observer on the transparent flat plate An electroluminescent element is formed by sequentially forming substantially matching mesh-like metal thin film electrode layers, and the electroluminescent element is sealed with a transparent plate or a transparent sheet, and the transparent plate is placed on the viewer side of the electroluminescent element. Alternatively, a transparent plate or a transparent sheet different from the transparent sheet is disposed without being in close contact with the transparent plate or the transparent sheet.
[0012]
(8) An organic electroluminescent element is used as the electroluminescent element. In the liquid crystal display device of the present invention, the illuminating device is disposed in front of a display surface of a liquid crystal display body.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1A, a net-like electroluminescent element 12 is formed on the surface of a transparent plate 11. Details of the electroluminescent element 12 are shown in FIG. The metal thin film electrode layer 13, the light emitting layer 14, and the transparent electrode layer 15 are sequentially formed on the transparent plate 11, and the light emitting layer 14 emits light by applying a voltage between the metal thin film electrode layer 13 and the transparent electrode layer 15. At this time, since the observer has the metal thin film electrode layer 13 in front of the light emitting layer 14, the illumination light does not reach the observer directly, and the illuminated body 16 can be efficiently illuminated. Further, as described above, since the electroluminescent element 12 is net-like, a portion where no element is formed is transparent, and an observer can observe the illuminated body 16 through the illumination device.
[0014]
The transparent plate 11 may be anything as long as it is a transparent material, such as a transparent resin plate or sheet such as an acrylic resin, a polycarbonate resin, or an amorphous polyolefin resin, a transparent sheet such as a polyethylene terephthalate (PET) resin, or an inorganic transparent plate such as a glass plate. Materials etc. are used. In the case where a resin sheet is used for the transparent plate 11, a flexible lighting device with high tolerance to bending can be realized. The electroluminescent element 12 has a structure in which a light emitting layer 14 is sandwiched between a metal thin film electrode layer 13 such as silver or aluminum and a transparent electrode 15 such as ITO (indium tin oxide). The light emitting layer 14 is inorganic or organic. An electroluminescent material is used. In particular, organic electroluminescent materials have high luminance and high efficiency can be expected. As organic light emitting materials, quinolinol aluminum complex (light emission color is green), zinc oxazole complex (same blue), zinc 2- (2-hydroxyphenyl) benzothiazole complex (same white), etc. are known, These can be used.
[0015]
Although the electroluminescent element 12 is formed in a thin line shape and has a net-like shape as a whole, this portion obstructs the visibility of the illuminated body 16 somewhat. When used for a display body or the like, it is desirable to form with a width of 100 μm or less. The electroluminescent element 12 can be set with an arbitrary area ratio with respect to the area of the entire illumination unit. However, by increasing the area ratio of the electroluminescent elements, the illumination intensity can be increased, but the ratio of vertically transmitted light is reduced and visibility is lowered. In practice, it is not practical to set the area ratio to exceed 50%, and it is appropriate to set the area ratio to 20% or less for part-time illumination in the dark.
[0016]
As shown in FIG. 2, the shape of the electroluminescent element 12 can be arbitrarily selected depending on the combination with the object to be illuminated, such as a lattice shape.
[0017]
(Second Embodiment)
Hereinafter, another embodiment of the present invention will be described with reference to the drawings. In FIG. 3A, a net-like electroluminescent element 12 is formed on the surface of the transparent plate 11. Details of the electroluminescent element 12 are shown in FIG. A transparent electrode layer 15, a light emitting layer 14, and a metal thin film electrode layer 13 are sequentially formed on the transparent plate 11, and a voltage is applied between the metal thin film electrode layer 13 and the transparent electrode layer 15 to cause the light emitting layer 14 to emit light. At this time, since the observer has the metal thin film electrode layer 13 in front of the light emitting layer 14, the illumination light does not reach the observer directly, and the illuminated body 16 can be efficiently illuminated. Further, as described above, since the electroluminescent element 12 has a net shape, a portion where no element is formed is transparent, and an observer can observe the illuminated body 16 through the illumination device.
[0018]
In this case, the transparent electrode layer 15 does not necessarily have a net shape. When the transparent electrode layer 15 is formed on the entire surface of the transparent plate 11, the resistance value can be kept low, which is advantageous for improving the efficiency. In addition, the shape, size, and the like of the electroluminescent element 12 are the same as those in the first embodiment.
[0019]
In FIG. 4, a transparent plate or a transparent sheet 17 is disposed on the observer side of the transparent plate 11. The light guide plate 11 and the transparent plate or the transparent sheet 17 are not in close contact with each other, and an air layer exists. Since the light emitted from the light emitting layer 14 is transmitted through the transparent plate 11 and illuminates the illuminated body 16, there is a light beam that is also guided into the transparent plate 11. Therefore, if there is even a slight scratch on the surface of the transparent plate 11, the light beam that guides the inside of the transparent plate 11 is reflected, and can be confirmed from the observer side as a bright spot or bright line. These are not only unsightly for transmissive illumination, but also remarkably lower visibility such as a decrease in contrast. Since the transparent plate or the transparent sheet 17 has an air layer with respect to the transparent plate 11, the light flux from the transparent plate 11 does not enter, and even if a scratch is made here, no bright spot or bright line is generated. . Further, in this case, since the relative area of the scratch is small, the influence on the visibility with respect to the illuminated body 16 is very small. In order to use the illuminating device of this embodiment as the front surface illumination, the presence of the transparent plate or the transparent sheet 17 is essential. As the transparent plate or transparent sheet 17, an acrylic resin, a polycarbonate resin, an amorphous polyolefin resin, a transparent resin such as polyethylene terephthalate (PET) resin, an inorganic transparent material such as glass, or the like is used.
[0020]
(Third embodiment)
Hereinafter, another embodiment of the present invention will be described with reference to the drawings. 5A and 5B, the electroluminescent element 12 formed on the transparent plate 11 has a sealed structure with a transparent plate or a transparent sheet 18. Since the electroluminescent element is vulnerable to hydrolysis, the lifetime can be extended by adopting a laminate structure. FIG. 5A corresponds to the first embodiment, and FIG. 5B corresponds to the second embodiment. The transparent plate or transparent sheet 18 is made of an inorganic transparent material such as a transparent resin plate or sheet such as acrylic resin, polycarbonate resin or amorphous polyolefin resin, a transparent sheet of polyethylene terephthalate (PET) resin, or a glass plate.
[0021]
FIGS. 6 (a) and 6 (b) are examples in which the transparent plates 17 are arranged adjacent to each other corresponding to the embodiment of FIGS. 5 (a) and 5 (b). Since the light is guided into the transparent plate 11 and the transparent plate or the transparent sheet 18 by the laminate structure described above, the transparent plate or the transparent sheet 17 is disposed adjacently because it is vulnerable to scratches and dirt in accordance with the above-described contents. .
[0022]
(Fourth embodiment)
Hereinafter, another embodiment of the present invention will be described with reference to the drawings. FIG. 7 shows an example in which a liquid crystal display panel is used as an object to be illuminated as another embodiment. The illumination device 101 is disposed on the front surface of the liquid crystal display panel 102. A reflective plate 103 is disposed on the back surface of the liquid crystal display panel 102 to constitute a reflective liquid crystal display device. The illuminating device 101 has a function of projecting a light beam toward the liquid crystal display panel 102 and transmitting the light beam reflected by the reflecting plate 103 with almost no dispersion. This is used by turning off the illumination when there is sufficient external light. In this case, the illumination device 101 acts as a simple transparent plate and does not deteriorate the visibility and is effective in not affecting the display quality. When the lighting device 101 is turned on and used in a dark place where the outside light is not sufficient, the liquid crystal display panel 102 is illuminated, and the reflected light from the reflecting plate 103 is merely a transparent plate as when the lighting device 101 is turned off. Since it functions and transmits as it is, it is effective to maintain high visibility.
[0023]
Further, in the transmissive liquid crystal display device in which the illuminating device is arranged on the back surface of the liquid crystal display panel, light rays from the illuminating device are transmitted only once through the liquid crystal display panel to generate contrast in bright and dark areas. In the reflective liquid crystal display device in which the illumination device as described above is arranged on the front surface of the liquid crystal display panel, the light from the illumination device is transmitted through the liquid crystal display panel once, then reflected by the reflector and transmitted again, so that the contrast is higher. It becomes effective in order to obtain high visibility by becoming high.
[0024]
【The invention's effect】
According to the present invention, as described above, it is possible to provide a thin surface illumination suitable for a posting, a display body and the like using outside light.
[0025]
Further, in applications such as portable computer terminals, a liquid crystal display device with low power consumption and high contrast can be provided without reducing display quality even when the light is turned off in a bright place for power saving.
[Brief description of the drawings]
1A and 1B are a perspective view and a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is a perspective view showing another embodiment of the present invention.
FIG. 3 is a perspective view and a sectional view showing another embodiment of the present invention.
FIG. 4 is a cross-sectional view showing another embodiment of the present invention.
FIG. 5 is a sectional view showing another embodiment of the present invention.
FIG. 6 is a sectional view showing another embodiment of the present invention.
FIG. 7 is a cross-sectional view showing another embodiment of the present invention.
FIG. 8 is a cross-sectional view showing a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Transparent plate 12 ... Electroluminescent element 13 ... Metal thin film electrode layer 14 ... Light emitting layer 15 ... Transparent electrode layer 101 ... Illumination device 102 ... Liquid crystal display panel 103 ... Reflector plate

Claims (4)

An illuminating device that is disposed on an observer side of an object to be illuminated,
A transparent electrode layer, a net-like light-emitting layer, and a net-like metal thin film electrode layer that substantially matches the light-emitting layer are sequentially formed on the surface of the observer on the transparent flat plate to constitute an electroluminescent device,
A lighting device, wherein a transparent substrate or a transparent sheet is disposed on the viewer side of the net-like metal thin film electrode layer with an air layer between the transparent flat plate and the transparent flat plate. An illuminating device that is disposed on an observer side of an object to be illuminated,
A transparent electrode layer, a net-like light-emitting layer, and a net-like metal thin film electrode layer that substantially matches the light-emitting layer are sequentially formed on the surface of the observer on the transparent flat plate to constitute an electroluminescent device,
The electroluminescent device has a sealing structure with a transparent plate or a transparent sheet,
An illumination device, wherein a transparent plate or a transparent sheet different from the transparent plate or the transparent sheet is disposed on the viewer side of the electroluminescent element without being in close contact with the transparent plate or the transparent sheet.   The lighting device according to claim 1, wherein an organic electroluminescent element is used as the electroluminescent element.   4. A liquid crystal display device comprising the illuminating device according to claim 1 disposed in front of a display surface of a liquid crystal display body.

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