Hitachi, Ltd.

Teruo Matsuo

Atsushi Yoshida

Toshio Asano

Kazuo Majima

Jun Mochizuki

Yoshinori Oyamada

Daisuke Katsuta

Masao Taniguchi

Kinuyo Hagimae

Tadayoshi Ihara

An apparatus for identifying positions of pixel defects on a display screen, such as a cathode-ray tube or a liquid crystal display, operates to pick up an image signal of a display screen representing a predetermined image with an imaging camera, shift the image signal of the imaging camera by one pixel in one and another directions with respect to the display screen, and obtain a difference of a signal level between a defective portion and a normal portion on the screen, based on the signals obtained when the image signal of the imaging camera is shifted in one and another directions. The apparatus also serves to calculate a relative inclination between the imaging camera and the display screen for obtaining a difference of a signal level between a defective portion and a normal portion of each pixel. The results make it possible to clearly identify the difference of the signal level between the defective portion and the normal portion.

Method and apparatus for checking defect on display screen

For aging a cathode-ray tube which has a cathode capable of emitting an electron beam, a first electrode for limiting the electron beam, a second electrode for accelerating electrons of the limited electron beam, a third electrode for focusing the accelerated electron beam and an anode, the cathode is energized so that an electron beam is emitted therefrom while D.C. rated voltages are applied to the first and second electrodes, respectively, and first and second voltages are applied to the third electrode and the anode, respectively, for a predetermined time. The first and second voltages are time-varying within first and second zones each of which is between a first level lower than the D.C. rated voltage on the second electrode and a second level higher than the highest one of the voltages on the third electrode with which an electric current flows in the second electrode with the electron beam emitted from the cathode. The first time-varying voltage is in phase with and lower than the second time-varying voltage. The first time-varying voltage is varying so as to be at a level between the first and second levels at least for a part of the above-mentioned predetermined time.

Method of aging cathode-ray tube

Growing community of inventors

Mobara, Japan

Teruo Matsuo