Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2002-02-27
2003-09-30
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S169100, C313S506000, C313S520000, C257S040000, C257S103000
Reexamination Certificate
active
06628086
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a light emitting body, light emitting element and light emitting display device using the same and more particularly to the light emitting body and light emitting element which can secure practical light emission lasting time and to the light emitting display device using the light emitting body and light emitting element.
The present application claims priority of Japanese Patent Application No.2001-051410 filed on Feb. 27, 2001, which is hereby incorporated by reference.
2. Description of the Related Art
Generally, as a self-emitting body used for a display device, a field mission device and an electroluminescence (EL) device are available. The EL device can be classified into two types of devices, one being an organic EL device using an organic material as a light emitting layer and another being an inorganic EL device using an inorganic material as the light emitting layer.
The organic EL device is generally made up of an anode, a cathode and a super-thin film organic EL layer made of an organic light emitting compound and being sandwiched between the anode and the cathode. When a voltage is applied between the anode and cathode, a hole is injected from the anode into the organic EL layer and an electron is injected from the cathode into the organic EL layer where the hole and electron are re-bonded to each other. By energy occurring at this time, a molecule in the organic light emitting compound making up the organic EL layer is excited. A light emitting phenomenon occurs when the excited molecule is deactivated while being put into a ground state. The organic EL device is a light emitting body using this light emitting phenomenon.
The organic EL layer has a single-layer structure or a multi-layer structure including an organic layer called a light emitting layer in which light is emitted when the hole and electron are re-bonded together and at least one layer out of an organic layer called a hole transporting layer where the hole is easily injected into the organic EL layer and the electron is not easily moved therein and an organic layer called an electron transporting layer where the electron is easily injected into the EL layer and the hole is not easily moved therein.
In recent years, the organic EL device is under rapid development and becomes commercially practical. Such the organic El device is basically constructed so that a thin film made of a hole injecting material such as triphenyldiamine (TPO) or a like is grown, by a deposition method, on a transparent electrode (serving as a hole injecting electrode, that is, as an anode) made from indium tin oxide (ITO) or a like and then on the thin film is formed, in a stacked manner, a light emitting layer made from a fluorescent substance such as alumi-quinolinol complex (Alq
3
) or a like and on the light emitting layer is further formed a metal electrode (serving as an electron injecting electrode, that is, as a cathode) using such as silver (Ag), magnesium (Mg), or a like which provides a small work function. Such the organic EL device can provide very high luminance of hundreds cd/m
2
to ten-thousands cd/m
2
by application of a voltage as low as about 10 V, it is expected to be used in electrical components and/or display devices for household electrical appliance, automobiles, two-wheelers, airplanes, or a like. In such the above organic EL device, for example, an organic layer serving as a light emitting layer is put between a scanning (common line) electrode serving as the electron injecting electrode and a data (segment line) electrode serving as the hole injecting electrode, that is, the transparent electrode.
Moreover, the display device using the organic EL device described above can be roughly classified into two types of display devices, one being a matrix-type display device and another being a segment-type display device. In the matrix-type display device, a dot-matrix display is performed by arranging the scanning electrode and data electrode in a matrix form in which information such as an image, character or a like is displayed in a form of an aggregate of pixels made up of dots. In the segment-type display device, a predetermined content for a specified purpose is displayed as an individual and independent display unit having a predetermined shape and size. The segment-type display can be operated by a static driving method to cause the display unit to display individually and separately, however, the dot-matrix display device has to be operated by a dynamic driving method which causes each of the data lines and scanning lines to be driven in a timeshared manner.
The light emitting body making up a light emitting element portion in the organic EL device can be also classified into two types of light emitting bodies, one being a substrate surface light emitting body type and another being a film surface light emitting body type. The substrate surface light emitting body, is so constructed that a transparent electrode is formed on a transparent substrate and a light emitting layer is formed on the transparent electrode and a metal electrode is further formed on the light emitting layer and that light produced in the light emitting layer is transmitted and transferred through the transparent electrode and the transparent substrate to an outside. On the other hand, the film surface light emitting body is so constructed that a metal electrode is formed on a substrate and a light emitting layer is formed on the metal electrode and a transparent electrode is further formed on the light emitting layer and that light produced in the light emitting layer is transmitted and transferred through the transparent electrode and then from a side of a film being placed opposite to a surface of the substrate to the outside. An example of the substrate surface light emitting body is disclosed in a collection of articles titled “Appl. Phys. Lett., No. 51, pp. 913-915 (1987)”. An example of the film surface light emitting body is disclosed in the “Appl. Phys. Lett., No.65, pp. 2636-2638 (1994)”.
However, a fluorescent organic body used as a material for the light emitting layer in the conventional organic EL device used as the light emitting body or light emitting element is susceptible to moisture, oxygen, or a like. Moreover, a characteristic of the conventional electrode (hereinafter being called a facing electrode) being placed directly on the light emitting layer or with a hole injecting layer or an electron injecting layer being interposed between the light emitting layer and the facing electrode is easily deteriorated by oxidation. Because of this, when the conventional organic EL device is operated in the atmosphere, a characteristic of its light emission is rapidly deteriorated. If oxygen or moisture exists in the vicinity of the conventional organic EL device, organic materials are deteriorated easily by oxidation which causes peeling of the film and growth of a dark spot (non-emitting portion) and, as a result, a phenomenon with which no light is emitted occurs. This presents a problem in that a life of the organic EL device is shortened.
Therefore, in order to obtain a practical organic EL device, some improvements are necessary so that moisture or oxygen does not invade its light emitting layer and so that its facing electrodes are not oxidized.
To solve this problem, a method of encapsulating the organic EL device to seal out the oxygen is disclosed in, for example, Japanese Patent Application Laid-open No. Hei 5-182759, in which an organic EL device is covered with a moisture-resistant light curing resin layer and with a small and low water-permeable substrate being adhered on an upper portion of the light curing resin layer. Another method for encapsulating an organic EL device is disclosed in Japanese Patent Application Laid-open No. Hei 5-41281 in which the organic EL device is put into an inert liquid produced by using a fluorocarbon oil containing a dehydrating agent such as a synthetic zeolite. Still another met
Fujieda Ichiro
Fukuchi Takashi
Hayashi Kazuhiko
Tsuboi Shinzo
Philogene Haissa
Scully Scott Murphy & Presser
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