JPS556962A - X-ray television equipment - Google Patents

Abstract

PURPOSE: To avoid occurrence of the inappropriate exposure such as the overexpsure or the like caused by covering of the image formed with the negative image forming agent, by carrying out the X-ray control through amplification of the video signals corresponding to the entire photometric viewfield given from the television camera controller.

CONSTITUTION: The subject image formed by the X-rays emitted from the X-ray source is converted into an optical image and then picked up through TV camera 7 to be displayed on TV monitor 11. In this case, the video signals corresponding to the entire photometric viewfield are extracted from TV camera controller 10 through automatic exposure controller 12. Thise video signals are then integrated, and integrated value A is held. At the same time, the video signal integrates independently the signals of the fixed levles for the period in the fixed level range, and integrated value B is held. Then value A is amplified with variation of the amplification factor in accordance with value B, and the X-ray volume of X-ray tune 1 is controlled by the amplification output and through X-ray controller 13. In other words, the ratio of the area is detected for the part which is not covered by the negative image forming agent in the entire photometric viewfield in proportion to the ratio between the major and minor parts of the signal level of the video signal. And according to this ratio, a correction is given to the control output given to controller 13.

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