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US 6,605,898 B2Granted
CRT device with improved resolution
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsMasahide Yamauchi, Kazunori Ohta, Masahiko Sukeno, Takashi Itoh
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Abstract
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.
Claims18
A color CRT device, comprising:
- an electron gun including a control electrode and three cathodes, each cathode corresponding to a different color;
- and
- spot diameter control unit operable to control a spot diameter by varying, for each color, a difference between a cutoff voltage of a corresponding cathode and a voltage applied to the control electrode in accordance with a luminance signal that has the highest luminance level among luminance signals corresponding to the three colors.
A color CRT device, comprising:
- an electron gun including a control electrode and three cathodes, each cathode corresponding to a different color;
- and
- spot diameter controlling unit operable to control a spot diameter by varying, for each color, a difference between a cutoff voltage of a corresponding cathode and a voltage applied to the control electrode in accordance with a luminance signal of the color.
Dependencies are inferred from the claim text.