The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 29, 1984
Filed:
Jul. 31, 1981
Kazuhiro Kamemoto, Kumagaya, JP;
Tokyo Shibaura Denki Kabushiki Kaisha, Kawasaki, JP;
Abstract
A frequency synthesizer type of the channel selecting device using a PLL wherein the local oscillation output is frequency-divided by a predetermined frequency dividing ratio according to a channel and compared in phase with a reference oscillation output, a signal corresponding to the phase difference is supplied to a tuner to change the local oscillation frequency thereof. A horizontal synchronizing signal is detected to determine whether or not a broadcast signal is transmitted through the channel, and when no broadcast signal is transmitted through the channel. Other channels are searched successively until a channel through which a broadcast signal is transmitted is found. The channel selecting device shifts the local oscillation output of the tuner from the predetermined frequency dividing ratio at the time of channel searching to thereby make the local oscillation frequency lower than the normal local oscillation frequency and returns the lowered local oscillation of frequency to the predetermined frequency dividing ratio when the presence of the broadcast signal is detected.