Matsushita Electric Industrial Co., Ltd.

Yosuke Fujita

Tomizo Matsuoka

Atsushi Abe

Tsuneharu Nitta

Takao Tohda

Jun Kuwata

Masahiro Nishikawa

Fumio Fukushima

Yoji Fukuda

A dielectric thin film element comprising a dielectric substrate and a dielectric thin film formed on the substrate. The thin film is made of a perovskite type oxide and formed by sputtering in an atmosphere containing nitrogen, by which the dielectric constant and the breakdown electric field strength are greatly improved. Thin film devices using the film and a method for making the thin film are also described.

Dielectric thin film, and method for making the thin film

In a thin film EL display device wherein a transparent electrode, a first dielectric layer, an EL emission layer, a second dielectric layer and a back electrode are laminated in order on a transluscent substrate, a 10 nm-200 nm thickness of thin film made of calcium sulfide or a mixture containing calcium sulfide which is formed by an electron beam vapor deposition method provided between the first dielectric layer and the EL emission layer and between the EL emission layer and the second dielectric layer, thereby obtaining a thin film EL display device which maintains a stable operation for a long period even when it is driven by A.C. pulses which are a symmetric with respect to the time relationship of the driving pulses (e.g., the time period between the start of a positive pulse and the start of the subsequent negative pulse is different than the time period between the start of a negative pulse and the start of the subsequent positive pulse) or are different in amplitude in a positive side and a negative side.

Thin film electroluminescence display device

An electroluminescent display panel formed of phosphor and dielectric layers sandwiched between opposing mutually intersecting arrays of drive electrodes, has the thickness of the phosphor layer set to a value which provides minimum power consumption, for a given level of display brightness. This is achieved by determining a value of capacitance per unit area of the panel which results in a maximum allowable value of time being required to charge each display element, then determining a value of phosphor layer thickness providing minimum power consumption, using the latter value of capacitance and the known value of light emission efficiency of the display.

Electroluminescence display panel configured for minimized power

An electroluminescent display device comprising an electroluminescent emitting layer including zinc oxide containing a luminescent active material, an insulating layer formed on one surface of the electroluminescent emitting layer and a pair of energizing means for applying signal voltages corresponding to an information to be displayed to a multilayer assembly including the said two layers, characterized in that a plurality of semiconductor layers each containing at least one chemical compound selected from the group consisting of chemical compounds of the II-VI groups and tin oxide are arranged as one of the energizing means arranged on the side of the electroluminescent emitting layer or between the energizing means arranged on the side of the electroluminescent emitting layer and the electroluminescent emitting layer. This device features that it requires only a reduced drive voltage for image displaying purposes and ensures an increased luminescent brightness.

Electroluminescent display device

Electroluminescence display device containing a zinc sulfide emission

New black color insulator thin films comprising Pr oxide, composite oxides of Pr-Mn, Pr-Ni, Pr-Co or Mn oxide are used to constitute at least one part or all parts of interface film between a phosphor film and a back electrode film of an AC thin film EL panel; and the panel with such a high contrast as 5:1 even at an illumination of 400 lux has been obtained.

Thin film EL panel

An electroluminescent element, especially a thin-film electroluminescent element in which the dielectric film layer provided on at least one side of an electroluminor layer is essentially composed of the materials represented by the following compositional formula:

Thin-film electroluminescent element

The development of a dielectric thin-film which is high (140 MV/cm or above) in product of dielectric constant .epsilon..sub.i and dielectric breakdown field strength E.sub.ib is essential for realizing an EL element which can operate stably at a low voltage. Such dielectric film is also required which can withstand heat treatments at high temperatures above 500.degree. C. and is proof against clouding and in which the electrical breakdown caused by a minute fault produced in the process of film formation is self-healed. A film material which satisfies all of these requirements could be obtained from a TiO.sub.2 -BaO based composition by partially substituting the position of Ti with Sn, Zr or Hf and also partially substituting the position of Ba with Ca or Mg. By using these dielectric films, it is possible to obtain a low-voltage drive thin-film electroluminescent element which are high in production yield and reliability.

Thin film electroluminescent element

A ceramic luminescent device, in which a luminescent screen of zinc sulfide layer with luminescent impurities is formed on a translucent zinc oxide sintered body, and the luminescent light emitted from said luminescent screen is derived through said zinc oxide body. The device can be constructed in a manner that said luminescent screen is excited either by an electric field or electron beam.

Ceramic luminescent device

Highly densed zinc sulfide ceramic materials, which essentially comprise zinc sulfide and alkali metals and/or alkaline earth metals and impurities acting as luminescent center, and which show a high brightness of cathode luminescence under irradiation of electron beam having a low energy, are easily made in the form of the sintered material, by heating the mixture of the said materials in inert or sulfuring atmosphere.

Growing community of inventors

Ashiya, Japan

Yosuke Fujita