Signal seeking type auto-tuning television receiver

Claim 1

In a signal seeking type auto-tuning television receiver having a tuning means including a reversely biased voltage variable capacitance diode in a signal selection circuit and which converts a selected television signal to picture and sound intermediate frequency signals, an intermediate frequency amplifier which is coupled to said tuning means and is provided with a predetermined band pass characteristic within which said picture and sound carrier signals are correctly converted to intermediate frequency signals, a stable D.C. power supply, and a sound intermediate frequency amplifier, the combination comprising: a scanning means coupled to said tuning means, said scanning means having means for supplying a sweep voltage to said voltage variable capacitance diode for scanning through the frequency spectrum of a television band; a driving means coupled to said scanning means for driving said scanning means; a control circuit means coupled to said driving means for controlling said driving means; a main signal detecting circuit means connected with said IF amplifier, said means including a limiter having a filtering circuit for rejecting undesired signal components and further including a frequency discriminator having a resonant circuit tuned to a first predetermined frequency for detecting sound IF carrier signals which are in said predetermined frequency and for developing a main control signal at the output of said frequency discriminator; a subsidiary signal detecting means connected in parallel with said main signal detecting circuit means, said means including a tuned amplifier tuned to a second predetermined frequency, a detector coupled to said tuned amplifier and having a resonant circuit tuned to a synchronizing signal frequency for detecting the picture IF carrier signal at said second predetermined frequency, and a rectifier connected with said detector through said resonant circuit and for developing a subsidiary control signal; a gate circuit means connected between said main signal detecting means and said control circuit means, said means being controlled by said subsidiary control signal for feeDing said main control signal to said control circuit means; and a mechanical switching means coupled to said control circuit means, said control circuit means starting and stopping a signal seeking action through an action of said driving means according to the operation of said mechanical switching means and developing said main and subsidiary control signals.