Kabushiki Kaisha Toshiba

Kazunori Nakane

Kiyoshi Tokita

Masatsugu Inoue

Toshinao Sone

Takeshi Fujiwara

Hiroshi Urata

Ryuichi Murai

Tetsuo Hasegawa

Kazunori Satou

In a method of testing a color cathode ray tube, an electron gun assembly is energized to emit electron beams and only a horizontal deflection magnetic field is applied to the electron beams so that a line image is displayed on a screen. A degaussing coil is located in front of the panel and a degaussing magnetic field having a frequency the same as that of a commercial power source. Thereafter, the degaussing coil is moved in a direction away from the panel and is deenergized when the coil is removed from the panel at a predetermined distance. A vertical deflecting coil is energized to display an image and a picture quality of the tube is tested.

Method of degaussing a color cathode ray tube

A color cathode-ray tube apparatus comprising a video signal generator, a delay circuit, an electron gun assembly, a deflection yoke, a shadow mask, and a phosphor screen. The signal generator generates three video signals simultaneously. The delay circuit delays the first and second video signals with respect to the third video signal. The screen has phosphor elements regularly arranged. The electron gun assembly generates three electron beams at different times, in response to the three signals output by the delay means. These beams are applied to the phosphor screen, and the phosphor elements of the screen emit red light, green light and blue light. Any three electron beams the gun assembly emits simultaneously form three beam spots on the screen. These spots overlap for a distance longer than half the horizontal diameter of a beam spot formed by an electron beam of the greatest current which the gun assembly can generate. The shadow mask, located between the phosphor screen and the gun assembly, controls the beams, making them land at desired positions on the phosphor screen. The deflection yoke deflects the beams in the horizontal and vertical directions, such that the electron beams scan the entire screen. The beams, deflected in the horizontal direction, land at substantially the same point on the screen, forming a color pixel thereon.

Color cathode-ray tube apparatus

A degaussing current whose frequency is L Hz is supplied to a degaussing apparatus, and a constant amplitude vertical deflection current whose frequency is M Hz is supplied to a deflection yoke. The degaussing current is an A.C. current, and its frequency L Hz is determined such that the value of M/L is not an integer.

Color cathode ray tube set

A color picture tube of this invention has a CRT envelope having a substantially rectangular front panel, a phosphor screen formed on an inner surface of the front panel, a shadow mask which is detachably mounted on the panel adjacent to the phosphor screen by a supporting assembly, and a frame surrounding the shadow mask. The supporting assembly has a plurality of stud pins which project from the four corners of the front panel and leaf springs which are fixed at one end to a corresponding corner of the frame are detachably engaged at the other end with a corresponding stud pin. Each leaf spring has an elastically deformable portion between one end portion fixed to the frame and the other end portion engaged with the corresponding one of the stud pins. Angle .beta., defined by the axis of the elastically deformable portion a central line axis of the CRT envelope, and angle .alpha., defined by a line connecting an end portion of the elastically deformable portion on the side of the frame and the stud pin and the central line axis of the CRT envelope, have the following relation: .beta.&lt;.alpha.

Color picture tube with shadow mask support assembly

In a color cathode ray tube, a shadow mask and/or a panel is formed into the following shape. In the shadow mask and/or the panel, a radius of curvature at a central portion in a section taken along an X-Z parallel plane is larger than that at an effective diameter edge portion on the Y axis, and a radius of curvature at an effective diameter edge portion on the X axis is smaller than that at a diagonal effective diameter edge portion. In the panel, a difference between a thickness at an effective diameter edge portion and a thickness on the X axis in a section of the panel taken along a Y-Z parallel plane is maximum at a position between the center of the panel and the effective diameter edge portion on the X axis.

Color cathode ray tube

In a color picture tube in which a shadow mask is placed close to a phosphor screen inside an envelope which has an oblong-shaped panel, the shadow mask is supported at the four corners of the panel by plate spring members. The spring members are each constructed from a 1st member which is fixed so that it is easily mounted on and dismounted from the stud pins on the panel and a 2nd member which is welded to the mask frame of the shadow mask. These members are incorporated as one by face-welding together at their ends. In this type of spring member structure, the members work together to alleviate the bending deformation which is applied to the members through the repeated mounting of the shadow mask panel which accompanies production.

Growing community of inventors

Fukiage, Japan

Kazunori Nakane