Matsushita Electric Industrial Co., Ltd.

Matsushita Electronics Corporation

Masahiko Sukeno

Yasuyuki Ueda

Kazunori Ohta

Masahide Yamauchi

Takashi Watanabe

Takashi Itoh

A color picture tube apparatus having an inline electron gun that allows technology for applying a dynamic voltage to an OLF lens to be implemented, while avoiding design difficulties. Eave-shaped electrode plates are attached, parallel with each other in a horizontal scan direction, to a field-correction electrode plate, which is a horizontally long, flatten plate in which three holes are provided, and whose shape is similar to that of an aperture in a circumferential electrode. This structure allows quadrupole lenses to be formed as auxiliary lenses having strong focusing action horizontally and divergent action vertically, and thus an HV differential can be increased. As a result, it is possible to reduce the dynamic voltage without any of the design difficulties accompanying the prior art, in which eave-shaped electrode plates are not provided.

Color picture tube apparatus

A set of three cathodes, a control electrode, an accelerating electrode, a first focus electrode, a second focus electrode, a third focus electrode, a fourth focus electrode, a final accelerating electrode and a shield cup electrode are provided successively in an electron beam travelling direction. The shield cup electrode has a pair of screen-shaped electrodes that sandwich electron-beam through-holes in a vertical direction. A quadrupole lens that has a horizontal convergent action and a vertical divergent action is generated by an electrical potential difference between the screen-shaped electrodes and the final accelerating electrode. Accordingly, even if vertical and horizontal convergence power difference in a main lens formed by the fourth focus electrode and the final accelerating electrode is not large, a composite lens formed through a combination of the quadrupole lens and the main lens has strong horizontal convergence power and weak vertical convergence power.

Electron gun and color picture tube apparatus that attain a high degree of resolution over the entire screen

The present invention provides a high-resolution color picture tube device with a decreased beam spot diameter. The color picture tube device has an electron gun including cathodes, a control electrode, an accelerating electrode, a G electrode, a first focusing electrode, a second focusing electrode, and a final accelerating electrode that are arranged in this order. A voltage applied to the G electrode is obtained by dividing with a resistor a voltage applied to the final accelerating electrode, and when an electron beam is a non-deflection state, a relationship represented as Va>Vg >Vfoc is satisfied where Va, Vg , and Vfoc denote voltages respectively applied to the final accelerating electrode, the G electrode and the second focusing electrode. Thereby, the G electrode is applied with a high voltage independently for forming a prefocus lens.

Color picture tube device

A CRT device with an electron gun provided therein includes control means for controlling voltages applied to a cathode and a control electrode constituting the electron gun. The control means exerts control on each electrode voltage so that the difference between the cutoff voltage of the cathode and the voltage of the control electrode is greater when the luminance level of a luminance signal separated from picture signal is higher, thereby minimizing a spot diameter.

CRT device with improved resolution

In order to increase the horizontal diameter of the lens and reduce the horizontal diameter of the peripheral spot for improving the resolution along the periphery of the phosphor screen of an in-line color picture tube, the focusing grids are so formed that the focusing force of the lens action on low voltage side is weaker in horizontal direction than in vertical direction and the diverging force of the lens action on high voltage side is weaker in horizontal direction than in vertical direction. As a result, the horizontal lens diameter increases, and the horizontal diameter of the peripheral spot is reduced even in the case where the laterally elongated distortion becomes conspicuous due to the increasing trend toward the flattening or the increased deflection angle of the panel.

Color picture tube having reduced picture distortion

A color picture tube apparatus comprises cathodes, a control electrode, an accelerating electrode, a first focusing electrode, a second focusing electrode and a final accelerating electrode, a voltage applying means which applies a dynamic voltage which increases with increasing deflection angle to the second focusing electrode, a resistor which is connected between the first and second focusing electrodes. Electron beam through holes that are vertically oblong are provided at the facing sides of the second focusing electrode and the final accelerating electrode. A quadrupole electric field lens is formed wherein a focusing effect is obtained in the horizontal direction and a diverging effect is obtained in the vertical direction when the potential level of the second focusing electrode is higher than that of the first focusing electrode. A compensating means generates a combined focusing effect of the electric field lenses formed between the cathodes and the final accelerating electrode stronger in the horizontal direction than in the vertical direction when the potential levels of the first and second focusing electrodes are the same.

An in-line color picture tube compensates for the distortion in the illuminated spot at the peripheral portion of the screen in a horizontally oblong shape. In particular, with an increase in the beam diameter under large current, or flattening of the panel or increase in the deflection angle, the beam distorted easily. However, such distortion is made to be small by providing a quadrupole lens with strong power. The in-line color picture tube has an electron gun comprising three cathodes that are in-line arranged in horizontal direction, a control electrode, an accelerating electrode and a focusing electrode system. The focusing electrode system comprises a couple of focusing electrodes having the facing portion on which non-circular beam through holes are provided. A predetermined focus voltage is applied to the first focusing electrode. A voltage changing in accordance with a deflection angle of the beam is applied to the second focusing electrode. A beam through holes that are oblong vertically are provided on the control electrode facing the cathode; and the beam through holes that are oblong horizontally are provided on the control electrode facing the accelerating electrode.

Color picture tube

In a color picture tube having a wide and flat screen, one set of in-line three electron beam through holes on an end face of a first focusing electrode facing a second focusing electrode are formed with a vertically oblong rectangular shape, and the other set of in-line three electron beam through holes on an end face of the second focusing electrode facing the first focusing electrode are formed with a horizontally oblong rectangular shape, a pair of protrusions is provided on a pair of longer sides of each of the electron beam through holes. Therefore, intensive quadrupole fields, by which deflection distortion can be cancelled, can be generated. Fluctuation of the quadrupole fields due to interference of a dynamic voltage and focusing voltage, which are to be applied to the focusing electrodes, can be prevented.

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Takatsuki, Japan

Masahiko Sukeno