Abstract: A method and apparatus for determining a line start writing position of a scanning light beam in a scanning light beam writing system. A first detector and a second detector are positioned in the scan path of the scanning light beam for detection of the scanning light beam. The information obtained from the detector is used to determine the line start for commencing writing on a media and for monitoring and controlling the power level of the scanning light beam.

Abstract: A method and apparatus for detecting a scanning light beam used for writing onto a media. A detector is disposed in the scanning path for sending a signal to a first amplifier. A second amplifier is provided for providing a feed back loop to the first amplifier so as to maintain the first amplifier a predetermined level. A time delay circuit provided between the output of the second amplifier and first amplifier for delaying the signal from said second amplifier to said positive input of said first amplifier such that the output of the first amplifier is forced to a predetermined value when no signal is being produced by the detector.

Abstract: A method and apparatus for automatically compensating for variations in recording medium, performance of the recording/playback head and the efficiency of the head/medium interface during video recording is disclosed. Automatic compensation in the recording of the video signal is accomplished by first recording a test signal on the recording medium, reproducing the recorded test signal from the recording medium, measuring one or more characteristics of the test signal, modifying recording parameters based on the measured characteristics, erasing the recorded test signal, and recording a video image signal using the modified recording parameters.

Abstract: A manual AFT switch and a manual FINE TUNE switch are configured so that whenever the FINE TUNE switch is engaged the AFT detector output is automatically disconnected from the AFT input of a tuning voltage control circuit. Furthermore a loading circuit coupled to the AFT input and driven by either the AFT switch or FINE TUNE switch assures the desired impedance at the AFT input whenever the output of the AFT detector is so disconnected.Automatically defeating the AFT circuit during manual fine tuning tends to optimize fine tuning by eliminating a component of correction voltage contributed by the AFT system, a face of which the lay viewer is likely to be unaware.