Hitachi, Ltd.

Hitachi Displays, Ltd.

Other

Hitachi Nisshin Electronics Co., Ltd.

Sachio Koizumi

Toshifumi Komiya

Norio Iwamura

Terutoshi Ichihara

Kenji Suzuki

Hisao Nakamura

Yukio Suzuki

Sadanori Taguchi

Hiroshi Takanobu

Hiroshi Takakura

Akio Yamaguchi

Toshio Kawashima

A heat generating portion of a heater which is incorporated in an indirectly heated cathode structure of an electron gun for a cathode ray tube is formed by joining a first winding portion and a second winding portion which differ in the number of coil winding layers and by twisting and winding a joined body in a double helical structure. The present invention allows a cathode temperature to have a high temperature and hence, it is possible to enhance the electron irradiation characteristics even when a degree of in-tube vacuum is lowered.

Cathode ray tube

The indirectly heated cathode structure includes a base metal having a thermal electron emitting material layer, a cylindrical sleeve holding the base metal at one end portion thereof and housing a heating heater in the inside thereof, an support having a large-diameter portion and g a small-diameter portion, and a cathode disc having a large-diameter portion at the leg-portion-side of the heating heater and having a small-diameter portion at the heater-main-portion side of the heating heater, wherein an outer surface of another end portion of the sleeve and an inner surface of the small-diameter portion of the support are fixed to each other, and an outer surface of the large-diameter portion of the support and an inner surface of the small-diameter portion of the cathode disc are fixed to each other.

A cathode ray tube has a cathode and plural grid electrodes fixed by insulating support rods. The cathode is supported within an eyelet disposed within and bonded to a cup-shaped support by a crystallized glass. The cup-shaped support is fixed by the insulating support rods. The crystallized glass is formed by firing a glass composition composed chiefly of zinc oxide, boron oxide, silicon oxide, and magnesium oxide. The crystallized glass exhibits a ratio in intensity of a diffraction peak A to a diffraction peak B in a range from 0.25 to 0.80 in an X-ray diffraction analysis using X-rays of 0.154 nm in wavelength, where the diffraction peak A is in the vicinity of 2&thgr;&equals;25.5&deg;, the diffraction peak B is in the vicinity of 2&thgr;&equals;26.5&deg;, 2&thgr;is an angle which a diffracted X-ray beam from a specimen surface makes with an incident X-ray beam.

Cathode ray tube having improved indirectly heated cathode

A color cathode ray tube has an electron gun in its neck portion. Its focus electrodes and anode are fixed by two insulating support rods. A voltage-dividing resistor is disposed in the vicinity of one of the insulating support rods for producing an intermediate voltage applied to a first one of the focus electrodes adjacent to the anode by dividing an anode voltage. The voltage-dividing resistor includes an insulating film, a resistance pattern, an insulating substrate, and a second film containing an oxide of transition metal, in the order named from the insulating film toward the inner wall of the neck portion. A metal conductor surrounding the voltage-dividing resistor and the one of the insulating support rods is fixed to a second one of the focus electrodes which is disposed upstream of the first one of the focus electrodes in a path of the electron beams.

Color cathode ray tube having an internal voltage-dividing resistor

A cathode ray tube has a phosphor screen and an electron gun including an indirectly heated cathode structure and a plurality of electrodes disposed downstream of the indirectly heated cathode structure for projecting an electron beam toward the phosphor screen, and a deflection yoke for scanning the electron beam on the phosphor screen. The indirectly heated cathode structure includes: a base metal having an electron emissive material coating on an outer top surface thereof; a metal sleeve having the base metal attached to an end of the metal sleeve; a heater housed partly within the metal sleeve which includes a major heating portion formed of a spirally wound heating wire and leg portions formed of heating wires wound spirally in a plurality of layers; an insulating film covering the major heating portion and a portion of each of the leg portions continuous with the major heating portion; and a black coating film covering a portion of the insulating film extending from the major heating portion toward each of the leg portions, the whole of the black coating film being housed within the metal sleeve.

Cathode ray tube having an improved indirectly heated cathode structure

A cathode ray tube has an electron gun including an indirectly heated cathode structure having a heater therein. The heater has a major heating portion formed of a spirally wound heating wire and two leg portions connected to opposite ends of the major heating portion. The two leg portions are welded to electrical conductors for applying voltages thereto at portions in the vicinity of open ends of the two leg portions, respectively, and the heater is covered with an insulating film except for the portions for welding. The two leg portions includes at least five layers of winding formed by spirally winding heating wires identical with the heating wire of the major heating portion, and the numbers of turns per unit length in each of the at least five layers of winding are smaller than a number of turns per unit length of the heating wire of the major heating portion.

Cathode ray tube having an improved heater

A color cathode ray tube having at least an evacuated envelope comprising a panel portion having a phosphor screen formed on an inner surface thereof, a neck portion, and a funnel portion connecting the panel portion and the neck portion. A shadow mask is spaced from the phosphor screen and suspended within the panel portion, an in-line type electron gun is housed in the neck portion and include three cathodes, a first grid electrode spaced from the three cathodes and a plurality of electrodes spaced between the first grid electrode and the shadow mask for generating and directing three electron beams toward the phosphor screen. A deflection yoke is mounted in the vicinity of the junction between the neck portion and the funnel portion. The three cathodes are supported within three eyelets, respectively, and each of the three eyelets has a large-diameter upper portion facing the first grid electrode, a small-diameter lower portion for supporting the three cathodes and a funnel portion for connecting the large-diameter upper portion and the small-diameter lower portion, and being disposed within and bonded to a tubular cathode support at the large-diameter upper portion thereof by a bonding glass contained within the tubular cathode support. The bonding glass provides a protrusion beyond an upper open end of the tubular cathode support, and the protrusion is provided with a depressed step around a top edge thereof.

Cathode ray tube having an improved cathode structure

A color cathode ray tube has an electron gun in its neck portion. The electron gun includes plural focus electrodes and an anode fixed in axially spaced relationship by two support rods. The electron gun also includes a voltage-dividing resistor for producing a voltage applied to a first focus electrode by dividing a voltage applied to the anode, and a metal conductor surrounding the resistor and fixed to a second focus electrode upstream of the first focus electrode. The resistor is disposed in the vicinity of one of the support rods, is formed of an insulating film, a resistance pattern, and a substrate disposed in the order named from the insulating film toward the neck portion. The resistance pattern is such that a potential difference between the metal conductor and a portion of the resistance pattern facing the metal conductor is equal to or smaller than 4 kV.

A cathode ray tube is provided with a phosphor screen and an electron gun including a cathode having an electron-emissive material layer formed on a surface of a cathode base metal. The electron-emissive material layer includes a first layer made of an alkaline earth metal oxide on the surface of the cathode base metal, a second layer on a surface of the first layer which is an alkaline earth metal oxide layer containing at least one rare earth metal oxide in a range of 0.1 to 10 weight percent, the at least one rare earth metal oxide having a particle size distribution in which the number of particles having a maximum diameter over 5 &mgr;m m is one or none, the number of particles having a maximum diameter in a range of from 1 &mgr;m to 5 &mgr;m is in a range of from 2 to 30, as measured in an area of 45 &mgr;m&times;45 &mgr;m at a center of a top surface of the second layer, the maximum diameter being defined as a perpendicular projection, onto a horizontal direction, of tangents to extremities of a profile of each of the particles. The cathode base metal is made chiefly of nickel and containing at least one reducing agent, and a thickness of a portion of the cathode base metal in contact with the electron-emissive material layer is in a range of 0.10 to 0.16 mm.

Cathode ray tube having an improved cathode

A cathode ray tube includes a phosphor screen and an electron gun. The electron gun includes an indirectly heated cathode structure and plural grid electrodes in axially spaced relationship. The cathode structure includes a base metal having an electron emissive material coating and a heater for heating the base metal. The heater includes a major heating portion having a spirally wound heating wire and leg portions disposed at ends of the major heating portion, and each of the leg portions includes a first multilayer winding portion having heating wires wound spirally in plural layers and a second multilayer winding portion disposed intermediate between the major heating portion and the first multilayer winding portion and having heating wires wound in plural layers. The major heating portion and at least a portion of the second multilayer winding portion are covered with an insulating coating, the heater is welded to electrical conductors for applying a voltage thereto at the first multilayer winding portion, and the number of layers in the second multilayer winding portion is at least three and the number of layers in the first multilayer winding portion is larger than that in the second multilayer winding portion.

Cathode ray tube having an improved indirectly heated cathode

An electron gun for a cathode-ray tube for image display including a cathode having a sleeve made of a refractory metal, a support provided at one end of the sleeve and made of a refractory metal containing a reducing element, a heater arranged in a space defined by the sleeve and the support, and an electron emissive material layer for emission of electrons. The electron emissive material layer is mainly made of an oxide of an alkaline earth metal and contains an oxide of a rare earth metal. The electron emissive material layer is prepared by forming a first layer on the support by spraying, and forming a second layer on the first layer by spraying. A dispersion amount of an oxide of a rare earth metal in the second layer is larger than that in the first layer and a first grid electrode is provided adjacent the cathode. The grid electrode has an electron beam passage hole for the electrons from the electron emissive material layer, and the electron beam passage hole has a diameter which is less than 0.4 mm.

ELECTRON GUN FOR CATHODE-RAY TUBE FOR IMAGE DISPLAY HAVING AN ELECTRODE WITH REDUCED ELECTRON BEAM PASSAGE HOLE AND A CATHODE WITH AN ELECTRON EMISSIVE LAYER MAINLY MADE OF AN OXIDE OF AN ALKALINE EARTH METAL AND CONTAINING AN OXIDE OF A RARE EARTH METAL

A cathode ray tube include phosphor screen and an electron gun. The electron gun includes an indirectly heated cathode structure and plural grid electrodes arranged in axially spaced relationship. The cathode structure includes a base metal having an electron emissive material coating and a heater for heating the base metal. The heater includes a major heating portion having a spirally wound heating wire and a pair of leg portions connected to opposite ends of the major heating portion. The major heating portion and an inner portion of each of the leg portions on a major-heating-portion side thereof are covered with an insulating coating, and the heater is welded to electrical conductors for applying a voltage thereto at an outer portion of each of the leg portions, the outer portion not being covered with the insulating coating. The outer portion of each of the leg portions includes a first multilayer winding portion having heating wires wound spirally in plural layers, and the inner portion of each of the leg portions includes a second multilayer winding portion having heating wires wound spirally in plural layers. The number of turns per unit length in the first multilayer winding portion is smaller than that in the second multilayer winding portion.

Cathode ray tube having an indirectly heated cathode provided with a heater having a structure which substantially prevents cracks in an insulating coating thereof

A cathode ray tube includes a phosphor screen and an electron gun. The electron gun includes an indirectly heated cathode structure and plural grid electrodes in axially spaced relationship. The cathode structure includes a cap-shaped base metal having an electron emissive material coating and a heater for heating the cap-shaped base metal. The heater includes a major heating portion having a spirally wound heating wire and leg portions, and each of the leg portions includes a first multilayer winding portion having heating wires wound spirally in plural layers and a second multilayer winding portion intermediate between the major heating portion and the first multilayer winding portion and having heating wires wound in plural layers. The major heating portion and at least a portion of the second multilayer winding portion are covered with an insulating coating, the heater is welded to electrical conductors for applying a voltage thereto at the first multilayer winding portion, and a number of turns per unit length in the first multilayer winding portion is smaller than that in the second multilayer winding portion.

A color cathode ray tube includes an electron gun having a plurality of cathodes and a cup-shaped first grid electrode spaced from the cathodes. The plurality of cathodes are supported within a plurality of eyelets corresponding to the number of the cathodes, respectively. The eyelets are disposed within and bonded to a tubular cathode support by bonding glass contained within the tubular cathode support, and satisfy the following relationship: (1.4 times a beam spacing S between two electron beams from the two adjacent cathodes divided by an outside radius of the eyelets-1.4 mm).gtoreq.(a height of the eyelets protruding beyond the top surface of the bonding glass).gtoreq.(0.98 times the beam spacing S divided by the outside radius of the eyelets-1.4 mm).

A cathode-ray tube is provided with an electron gun having a cathode and a control electrode and some other electrodes. The cathode includes an electron emissive material layer for emission of electrons through a hole in the control electrode. The hole in the control electrode has a diameter substantially in a rage of from 0.3 mm to 0.4 mm. The electron emissive material layer has a first layer made of an oxide of an alkaline earth metal formed on a support and containing no oxide of a rare earth metal, and a second layer made of an oxide of an alkaline earth metal formed on the first layer and containing an oxide of a rare earth metal substantially in an amount of from 0.8 wt % to 5.0 wt %.

Growing community of inventors

Mobara, Japan

Sachio Koizumi