Kabushiki Kaisha Toshiba

Tsutomu Takekawa

Hirofumi Ueno

Kazunori Satou

Noriyuki Miyamoto

Shigeru Sugawara

Tomonari Ishihara

Masatane Jida

A prefocus lens section is formed by a screen electrode and an additional electrode. A main lens section is formed by a focus electrode, an anode electrode and an intermediate electrode that is disposed between the focus electrode and the anode electrode. Each of the focus electrode and the intermediate electrode has a cylindrical electrode on at least one of opposed faces thereof. The intermediate electrode and the anode electrode have cylindrical electrodes on opposed faces thereof. A voltage with a level higher than a focus voltage and lower than an anode voltage is applied to the additional electrode and the intermediate electrode.

Cathode-ray tube apparatus

A prefocus lens section is formed by a second grid and a third grid in a substantially rotation-symmetric fashion. A sub-lens section is formed by the third grid and a first segment. A main lens section is formed by a fourth grid and a fifth grid. The third grid is supplied with a voltage that is higher than a focus voltage and lower than an anode voltage. An electron beam, which is prior to entering the main lens section, is shaped to have a greater horizontal dimension than a vertical dimension.

At least one of the electrodes of an electron gun assembly is constructed by coupling at least first and second electrode members arranged in a direction of passing of electron beams. The first electrode member has a projecting portion on an end face thereof, which is to be coupled to the second electrode member disposed adjacent to the first electrode member. The first electrode member is coupled to the second electrode member via the projecting portion.

In an electron gun for a color cathode ray tube apparatus of this invention, one intermediate electrode is arranged between a final acceleration electrode and a focus electrode that make up a main lens, and a voltage divided by a voltage dividing resistor for dividing a voltage to be applied to the final acceleration electrode is applied to the intermediate electrode. A dynamic voltage which increases along with an increase in deflection amount of an electron beam is applied to the focus electrode, and a dielectric portion is formed between the final acceleration electrode and the focus electrode. This dielectric portion is formed on the intermediate electrode. Hence, elliptical distortion of electron beam spots is decreased on the entire surface of a phosphor screen, thereby providing a color cathode ray tube apparatus with a good performance on the entire surface of the phosphor screen.

Color cathode ray tube apparatus with an electron gun having an intermediate electrode

An electron gun assembly in a cathode-ray tube apparatus includes a quadrupole lens that is created in accordance with deflection of electron beams. The quadrupole lens is created by two mutually opposing grids. The two grids have non-circular electron beam passage holes in their mutually facing surfaces. Each electron beam passage hole has a waist portion which minimizes a horizontal or vertical dimension of a region for passing the associated electron beam.

An electron gun structure applied to a color cathode-ray tube comprises a focus electrode, an ultimate acceleration electrode and at least one intermediate electrode disposed between the focus electrode and the ultimate acceleration electrode, the focus electrode, the ultimate acceleration electrode and the at least one intermediate electrode forming a main lens. The electron gun structure also comprises a voltage application unit for applying to the focus electrode a dynamic voltage increasing in accordance with an increase in a degree of deflection of the electron beams, and applying to the intermediate electrode a voltage obtained by dividing a voltage applied to the ultimate acceleration electrode by means of a voltage dividing resistor. The electron gun structure further comprises at least one cylindrical additional electrode electrically insulatively covering a part of the electrode constituting the electron lens, the at least one cylindrical additional electrode being electrically connected to the intermediate electrode.

Color cathode-ray tube apparatus with multi-lens electron focusing and yoke deflection

A color cathode-ray tube apparatus comprises an electron gun structure having a plurality of electrodes for constituting a plurality of electron lenses including a main lens for focusing an electron beam on a phosphor screen, and a deflection yoke for producing deflection magnetic fields for deflecting the electron beam emitted from the electron gun structure in a horizontal direction and a vertical direction. An electron beam passage hole formed in at least one of the electrodes constituting the main lens has a waist portion substantially acting on formation of the electron lenses. The waist portion minimizes a horizontal dimension of a region where the electron beam passes.

Color cathode-ray tube apparatus

An electron gun assembly has at least one additional electrode located along the equipotential plane of a potential distribution formed between a focusing electrode and anode electrode forming a main lens. In a no-deflection state, the additional electrode receives a voltage of a predetermined level corresponding to the potential of the equipotential plane on which the additional electrode is located. In a deflection state, letting Vf be the application voltage of the focusing electrode, Eb be the application voltage of the anode electrode, and Vs be the application voltage of the addition electrode, a value (Vs&minus;Vf)/(Eb&minus;Vf) changes with an increase in electron beam deflection amount, while the additional electrode forms an electron lens having different focusing powers in the horizontal direction and vertical direction.

Color cathode ray tube apparatus

An electron gun assembly forms an electron beam generator, pre-focusing lens, sub-lens, and main lens. The sub-lens has a weaker horizontal focusing power than the vertical one, and the main lens has a stronger horizontal focusing power than the vertical one. When the electron beam is not deflected, a first quadrupole lens is formed between the pre-focusing lens and sub-lens, and a second quadrupole lens is formed between the sub-lens and-main lens. At least one grid forming each of the first and second quadrupole lenses receives a dynamic focusing voltage which parabolically changes in synchronism with the deflection magnetic field and becomes higher when the electron beam is deflected than when it is not deflected.

Cathode ray tube apparatus

A cathode structure comprises a cathode, a cathode sleeve, a cathode holder and a cathode strap. The cathode sleeve contains a heater. A hold structure includes a cylindrical cathode support cylinder for holding the cathode structure, and a cathode support strap having an elongated plate shape and having a cylindrically curved portion engaging the cathode support cylinder. An opening portion is formed in the cylindrically curved portion of the cathode support strap. The cathode support cylinder of the hold structure and the cathode holder of the cathode structure are welded through the opening portion, and the cathode structure is held by the hold structure.

Electron gun structure including cathode support strap with opening portion

In a self-convergent type color cathode ray tube apparatus, three in-line electron beams emitted from an electron gun assembly are deflected by non-uniform magnetic fields generated by a deflection yoke and thus self-converged onto a screen. The electron gun assembly has a second grid and a third grid. First and second auxiliary grids are disposed between the second and third grids. A dynamic voltage varying in synchronism with deflection of the electron beams is applied to the first auxiliary grid situated on the second grid side. A fixed voltage is applied to the second auxiliary grid situated on the third grid side. Accordingly, the second grid, the first and second auxiliary grids and the third grid form an electron lens such that a higher astigmatism is provided by focusing in a direction perpendicular to a direction of arrangement of the three electron beams than by focusing in the direction of arrangement of the three electron beams and the degree of the astigmatism is dynamically varied. A color cathode ray tube apparatus capable of performing uniform focusing over the entire screen with a relatively low dynamic voltage is provided.

Color cathode ray tube apparatus having auxiliary grid electrodes

A color cathode-ray tube apparatus comprises an electron gun structure for generating three electron beams arranged in line, the three electron beams comprising a center beam and a pair of side beams. The electron gun structure forms a main lens for ultimately focusing the three electron beams on a phosphor screen. The main lens is formed by a focus electrode, an additional electrode and an anode electrode which are arranged in a direction of traveling of electron beams. A voltage application unit applies a voltage to each of the electrodes such that a voltage higher than a voltage applied to the focus electrode and lower than a voltage applied to the anode electrode is applied to the additional electrode, and in synchronism with deflection of the three electron beams by the deflection yoke, a value S varies: S&equals;&lsqb;(applied voltage to the additional electrode)&minus;(applied voltage to the focus electrode)&rsqb;/&lsqb;(applied voltage to the anode electrode)&minus;(applied voltage to the focus electrode)&rsqb;. An angle of emission of each of the side beams emanating from the main lens varies in synchronism with a variation of the value S.

An electron gun comprises a supplementary grid applied with a voltage which dynamically changes in synchronization with a magnetic field generated by a deflection yoke, between a second grid and a third grid. Further, by the second grid, the supplementary grid, and the third grid, an electron is constructed which has an astigmatic aberration in which a focusing force in the horizontal direction is stronger than a focusing force in the vertical direction. The intensity of the astigmatic aberration of the electron lens is dynamically changed by a voltage applied to the supplementary grid.

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Fukaya, Japan

Tsutomu Takekawa