Automatic calibration circuit for monitoring device

摘要

An automatic calibration circuit for a monitoring device in which a static image, such as may be derived from an X-ray camera or an ultrasonic imaging device, is displayed as a static image on CRT and the image projected and recorded on film. A uniform pattern is displayed on the CRT by setting a contrast control signal to a minimum value and a brightness control signal to a reference level. Then, the light outputted from the face of the CRT is measured at any arbitrary point on the face of the CRT. The value so measured is used to correct the brightness signal and contrast signal so as to maintain initially set brightness and contrast values for images displayed on the CRT.