Matsushita Electric Industrial Co., Ltd.

Other

Matsushita Electric Co., Ltd.

Hideharu Ohmae

Masahiko Konda

Ryuichi Murai

Mitsuhiro Ohtani

Katuyoshi Yamashita

Yoshikazu Demi

Masatoshi Kudoh

Masayuki Ohmori

Shinji Tsuge

Noriaki Nagao

Tatsuo Yoshii

Susumu Okuji

Makoto Okuji

Hirotoshi Watanabe

Mitsunori Yokomakura

Nozomu Arimoto

Hideaki Etou

Masayoshi Ozaki

Toshiharu Hoshi

This invention provides a mask frame for a color CRT made from a steel composition consisting essentially of, in mass %, C: 0.03-0.30%, Si: at most 0.30%, Mn: 0.05-1.5%, P: at most 0.05%, S: at most 0.02%, Mo: 0.02-0.50%, V: 0.02-0.20%, Al: at most 0.10%, N: 0.0040-0.0200%, Cu: at most 1.0%, Ni: at most 1.0%, Cr: at most 2.0%, W: at most 1.0%, B: at most 0.003%, Ti: at most 0.030%, and Nb: at most 0.030%, and a balance of iron and unavoidable impurities, with Al&lE;(7.0)N, and having a metal structure in which the ferrite grain size is at most 15 micrometers and the ferrite volume ratio is at most 90%.

Color CRT mask frame, a steel sheet used therefor and a manufacturing method for the steel sheet, and a color CRT equipped with the frame

A metal material is rolled to form a strip plate material having a middle part and thinner thickness-deviation portions on both sides of the middle part. After that, this strip plate material is bent and deformed in its width direction by roll forming, thus forming a bent and deformed portion in the middle part. The processing method includes a rolling step and a roll forming step, which enables the metal material to be processed economically using relatively simple steps. No annealing step is included and therefore an excellent final product is obtained. Particularly, the rolling step and the roll forming step are carried out successively, so that the roll forming can be carried out with high efficiency using processing heat generated in the rolling step. The bent and deformed portion is thick and the thickness-deviation portions are thinner, which contributes to the reduction in weight of a final product while the same strength as that of a conventional product is maintained.

Method of processing bent and deformed portion of metal material

This invention provides a steel sheet for a mask frame which maintains a tension-type color CRT shadow mask under tension. The steel sheet has a steel composition consisting essentially of, in mass %, C: 0.03-0.30%, Si: at most 0.30%, Mn: 0.05-1.5%, P: at most 0.05%, S: at most 0.02%, Mo: 0.02-0.50%, V: 0.02-0.20%, Al: at most 0.10%, N: 0.0040-0.0200%, optionally one or two or more of Cu: at most 1.0%, Ni: at most 1.0%, Cr: at most 2.0%, W: at most 1.0%, B: at most 0.003%, Ti: at most 0.030%, and Nb: at most 0.030%, and a balance of iron and unavoidable impurities, with Al&lE;(7.0)N, and having a metal structure in which the ferrite grain size is at most 15 micrometers and the ferrite volume ratio is at most 90%. The steel sheet is manufactured by hot rolling of a slab having the above-described steel composition under the conditions of a finishing temperature of 820-950&deg; C. and a coiling temperature of 400-700&deg; C.

Steel sheet used for color CRT mask frame and a manufacturing method for the steel sheet

An electron gun that can provide a desired electron beam modulation effect without preventing a modulation magnetic field from passing from an exterior of the vacuum portion is provided. A part of a tubular G3 electrode in an electron gun is formed into a coiled portion to allow the modulation magnetic field to pass through the clearances between parts of a wire composing the coiled portion.

Electron gun comprising a tubular electrode having a coiled portion formed therein

A cathode ray tube capable of reducing the doming amount and suppressing the occurrence of moire stripes at the same time with improved effects to suppress the occurrence of moire stripes even more is provided. The protruding portions are protruding from the ends of the horizontal direction of the aperture to the inside of the aperture . With regard to the horizontal cross sections of the protruding portions , the portions facing each other left and right via the aperture are formed to be asymmetrical to the center line in order to reduce or block the incident electron beam. By forming the protruding portions , the doming amount can be reduced and the occurrence of moire stripes can be suppressed at the same time. Furthermore, by forming the portions facing each other left and right of the protruding portions asymmetrically, the effects to suppress the occurrence of moire stripes can be improved even more.

Cathode ray tube

A cathode ray tube capable of reducing the doming amount and suppressing the occurrence of moire stripes at the same time, which also can prevent the so-called persimmon stone phenomenon from occurring, is provided. In the apertures, the protruding portions that are protruding from end faces in the horizontal direction of the apertures to the inside of the apertures are formed. The protruding portion in the aperture located on the right side of the phosphor surface from the vertical center line of the shadow mask is protruding in the direction toward the peripheral portion on the right side, while the protruding portion in the aperture located on the left side of the phosphor surface is protruding toward the peripheral portion on the left side. Accordingly, the doming amount can be reduced and the occurrence of moire stripes can be suppressed at the same time, while the persimmon stone phenomenon in which the beam spot of an electron beam on the phosphor surface is cut partially can be prevented from occurring.

Cathode ray tube having apertured shadow mask

A cathode ray tube includes a pair of plate members ( ) facing each other, a pair of supporters ( ) adhered to the respective plate members ( ) to support the plate members ( ), and a shadow mask ( ) adhered to the respective plate members ( ) while being applied with tensile force. The supporters ( ) have crank-shaped steps ( ) formed to protrude toward the shadow mask ( ). Thereby, an internal moment of a shadow mask structure can be decreased, and thus, displacement of the shadow mask ( ) in the axial direction is suppressed even when the shadow mask ( ) is expanded by heat generated by impact of electron beams, and q-value deviation is suppressed as well. Moreover, since the crank-shaped steps ( ) are helpful in blocking a transverse clearance with a ferrous material, the magnetic properties can be improved.

Cathode ray tube with supporters having crank-shaped steps

In a color cathode-ray tube with a shadow mask stretched and held by supporters while being provided with a tensile force, a member with a substantially L-shaped cross-section is used for each of the supporters, which is obtained by forming of a strip plate material having a middle part and thinner thickness-deviation portions on both sides of the middle part by rolling of a metal material; and then bending and deforming of the strip plate material in its width direction by roll forming to form a bent and deformed portion in the middle part. The supporter obtained by such a method can be reduced in weight while maintaining substantially the same strength as that of a conventional product, can be processed economically in relatively simple steps, and has less thickness variation. Therefore, an inexpensive color cathode-ray tube having stable qualities and causing less color unevenness can be provided.

Color cathode-ray tube

A cathode ray tube capable of reducing a doming amount and suppressing an occurrence of moire stripes by providing protruding portions in a slot aperture of a tension type shadow mask. In a cathode ray tube including a mask frame formed in the form of a frame, and a shadow mask made of a flat plate containing a plurality of slot apertures, which is stretched and held onto the mask frame with a tension force applied in the longitudinal direction of the apertures, the shadow mask is provided with bridges linking the slot apertures arranged neighboring in the longitudinal direction, and the slot aperture is provided with protruding portions facing each other and protruding from the both ends in the lateral direction of the slot aperture into the inside of the slot aperture. Thus, it is possible to reduce the doming amount and to suppress an occurrence of moire stripes, while securing the mechanical strength and luminous intensity.

Method and apparatus for manufacturing an electron gun. A beam spot coefficient is obtained from an electrostatic lens magnification and a spherical aberration coefficient of a set resistance distribution. Then, a first process loop is executed to select another resistance distribution that provides an approximate minimum value of the beam spot coefficient. It is then determined whether the beam spot coefficient is an approximate minimum value. The first process loop is repeatedly executed until the beam spot coefficient is determined to be equal to the approximate minimum value. At this point, a second process loop is executed to confirm the minimum value of the beam spot coefficient using an aberration-independent function that is dependent upon the electrostatic lens magnification and is not dependent upon the spherical aberration coefficient. Processing returns to the first process loop using still another resistance distribution as a selected resistance distribution when the beam spot coefficient is not the approximate minimum value.

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Osaka, Japan

Hideharu Ohmae