Video disc player
AssigneeUniversal Pioneer Corporation
InventorMinoru Kosaka
Life of this patent
Estimating the term…
Abstract
A video disc player featuring a signal correcting device capable of compensating for the attenuation of the signal level of high frequency components of the reproducing signal read out from an optically electromagnetically or electrostatically scanned video disc, a device for detecting the presence or absence of recorded information on a video disc being played back, or a tracking servo system which can be locked in reliably and in a stable condition when the servo loop is to be closed from an open condition.
Claims13
A video-disc information reading and reproducing apparatus including a source of a reproducing signal read out from a video disc, comprising in combination;
- gain control means having an input terminal connected to said source and a control terminal and operative to automatically regulating the signal level of said reproducing signal in response to a control signal supplied to said control terminal;
- equalizer means having an input terminal connected to said gain control means and a control terminal and operative to produce an output signal having a gain which has a frequency characteristic variable in response to a control signal supplied to the control terminal of the equalizer means;
- first filter means for passing therethrough a frequency modulated video carrier component contained in the output signal from said equalizer means;
- second filter means for passing therethrough a frequency modulated audio carrier component contained in the output signal from said equalizer means;
- first signal level detector means for supplying to the control terminal of said equalizer means control signal variable only with the signal level of said video carrier component;
- and
- second signal level detector means for supplying to the control terminal of said gain control means a control signal variable only with the signal level of said audio carrier component.
In a video-disc information reading and reproducing apparatus including a source of a reproducing signal read out from a video disc scanned by a detecting point which is deflected radially of the video disc and a signal correcting device which is operative to compensate for the attenuation of the signal level of high frequency components of said reproducing signal and which includes signal level detector means operative to produce an output signal variable with the signal level of a frequency modulated audio carrier component contained in the reproducing signal, a tracking servo system for deflecting said detecting point radially of said video disc, the tracking servo system comprising
- error signal producing means operative to produce a tracking error signal which is continuously variable in magnitude with the distance between the center line of a target track on said video disc and said detecting point to be placed on said target track and which has polarities respectively corresponding to the directions in which the said detecting point is to be deflected radially of the video disc,
- comparing means for comparing the output signal having a predetermined level for producing a track existance signal when the former is higher in level than the latter,
- control signal producing means responsive to said tracking error signal and said output signal from said comparing means and operative to produce a loop closure control signal when said tracking error signal has a predetermined level in the presence of said track existance signal from the comparing means, and
- switch means provided in the servo loop of said tracking servo system and operative to make operative the servo loop in response to the loop closure control signal so as to perform quick and smooth lock-in operation.
Dependencies are inferred from the claim text.