Hitachi, Ltd.

Hiroshi Fukushima

Takao Kawamura

Hisashi Ando

Ko Soeno

Hiroshi Sakamoto

Akira Misumi

Toshiyuki Aida

Shigehiko Yamamoto

Yukio Honda

Ushio Kawabe

Isamu Yuito

Tetsuo Kumazawa

Sadanori Taguchi

Yukihiro Izumida

Teruo Fujii

Yoshito Ohmura

Tatsuo Baba

Testuo Oyama

Yoshio Degawa

Takeo Takemoto

Masaru Nakazawa

Nobuo Nakai

Hideo Fukuma

A remote control system which is suitable for selective execution of any one of a plurality of functions of an automatic answering telephone apparatus by means of remote control over a telephone line. In the system, questioning speeches corresponding to the individual functions respectively are sequentially transmitted to the user of the apparatus, and the answer of the user to a specific question is detected to execute the specific function.

Remote control system

A directly heated cathode for electron tube having a stable electron emission characteristic is provided. The cathode comprises a base metal of Ni-W alloy consisting essentially of 20-30% by weight of tungsten, the balance being nickel and incidental impurities, said alloy being free from a reducing agent, and a layer of thermoelectron emission oxides laid directly and baked onto the flat part at the front side of the base metal. The layer of thermoelectron emission oxides is in direct contact with the flat part of the base metal.

Directly heated cathode for electron tube

A directly heated cathode for an electron tube comprising a base plate made of an alloy containing 20 to 30% by weight of W, 0.12 to 0.28% by weight of Zr and the remainder being Ni and an electron emissive oxide layer disposed directly on the base plate shows good and stable electron emission properties and when it is installed in a television picture tube, the picture tube shows excellent initial properties.

An electron tube cathode has a composite suppression layer structure interposed between the base metal and the electron-emitting material to suppress an interface layer formed through the reaction of the base metal with the electron emissive material. The composite layer structure includes a thin layer of Pt or Re and a layer of oxide of Zr and/or Hf. As a result, the formation of the interface layer is prevented so that the useful life of the electron tube cathode is prolonged.

Electron tube cathode

There is disclosed a direct-heated cathode structure which comprises an insulating substrate; a pair of conductive supporting rods penetrating the substrate in the direction substantially perpendicular to the surface of the substrate and fixed tightly to the substrate; and a conductive member made of a single metal plate and including a first portion which is arranged in a plane spaced apart from the surface of the substrate by a predetermined distance and substantially parallel to the surface of the substrate and is coated with an electron emissive material, second portions which are extended from the first portion in the above-mentioned parallel plane substantially symmetrically with respect to the first portion, third portions which are extended from the end of extension of each of the second portions in the direction substantially perpendicular to the surface of the substrate toward the substrate, and fourth portions which are extended from the ends of the third portions in the direction substantially parallel to the surface of the substrate in the same plane as the third portions and are fixed to the supporting rods in the neighborhood of the end of extension of the fourth portions. Each of the first, second and third portions has a side wall provided along at least a part of the edges of these portions and extending in the direction substantially perpendicular to the surfaces of these portions.

Direct-heated cathode structure

A directly heated cathode for electron tube having a stable electron emission characteristic and a low cut-off voltage is provided. The cathode comprises a base metal of an alloy consisting essentially of 20-30% by weight of tungsten and a trace amount to 0.25% by weight of zirconium, the balance being nickel, binder dots of metallic nickel powders distributed on a flat part at the front side of the base metal, and a layer of thermoelectron emission oxides laid on the flat part at the front side of the base metal. The layer of thermoelectron emission oxides is in direct contact with the flat part through clearances among the binder dots of the metallic nickel powders.

The output signal of an l-f (low-frequency) power amplifier is supplied to an electroacoustic transducer, through an inductive element for preventing parasitic oscillation, to cause the inductive element to generate a magnetic flux whose density depends on the output current signal of the power amplifier while a current according to the magnitude of the output voltage signal of the power amplifier is supplied to the current input terminals of a Hall-effect element disposed in the magnetic field induced by the inductive element, so that a voltage according to the output power of the l-f power amplifier is taken out of the output terminals of the Hall-effect element. When the voltage exceeds a predetermined level, the l-f signal supplied to the electroacoustic transducer is attenuated by a signal attenuating circuit so that the transducer is prevented from being damaged.

Protective circuit for electroacoustic transducer with hall element and

Growing community of inventors

Chiba, Japan

Hiroshi Fukushima