| 摘要 |
PURPOSE:To reduce scattering of brightness and swinging of an image and so on by linearly extending cathode electrodes in an electron beam generator and besides varying heating currents of the cathode electrodes as time passes. CONSTITUTION:Respective linear cathodes 1a to 1c are connected with tension of springs disposed on both ends or one sided ends of the cathodes. The one- sided ends of the cathodes 1a to 1c are connected with diodes 30a to 30c, respectively, and the one-sided ends of the diodes are jointed together and connected with an output of a modulation circuit 31. In the circuit 31, high frequency of a pulse signal 33 outputted from a cathode-heating pulse generating circuit 32 is modulated by a low-frequency modulated signal 35 outputted from an oscillation circuit 34. When a temperature of the linear cathodes changes as time passes, in such composition, the amount of thermal expansion in the linear cathodes is varied and so the intrinsic oscillation changes. Therefore, a resonance state of a frequency component involved in the beam modulation signal is not continued, so that scattering of brightness and swinging of an image and so on are reduced.
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