Television tuning system with precision substrate switch assembly
AssigneeZenith Radio Corporation
InventorJohn Y. Ma
Life of this patent
Estimating the term…
Abstract
A VHF television tuner system has four tunable circuits each including an abrupt junction varactor diode having a predictable capacitance-tuning voltage characteristic. The VHF frequency spectrum is divided into Lo and Hi bands encompassing television channels 2-6 and 7-13, respectively. A pair of voltage divider networks comprising precisely trimmed resistive material on a ceramic substrate provide tuning voltage terminals corresponding to the VHF television channels. The end terminals of each divider network are coupled to adjustable potentiometers for setting the tuning voltage at each extreme of the voltage divider. A substrate mounted switch accesses the tuning voltage points, supplies bandswitching voltages and provides AFC defeat between channels.
Claims17
An electronic television tuner system without a fine tuning control, for receiving and translating television signals in a fixed frequency range, having a plurality of tunable stages, each including an abrupt junction varactor diode displaying a capacitance-to-tuning voltage characteristic which is predictable from diode to diode, and means supplying the varactor diodes with tuning voltages for tuning said tuner to individual television signals in said fixed frequency range comprising:
- a source of regulated potential;
- a substrate including a stable voltage divider network comprising deposited resistors whose junctions form voltage terminals at which respective ones of said tuning voltages are developed;
- means on said substrate selectively connecting said voltage terminals to said tunable stages;
- and
- setting means on said substrate coupled between said source and said voltage divider network for establishing the tuning voltage at one of said voltage terminals to enable reception and translation of a corresponding one of said television signals.
A switch assembly for use with any of a plurality of abrupt junction varactor diode tuners for tuning television channel signals in a predetermined frequency range, said tuners including a plurality of varactor diodes having capacitance-tuning voltage characteristics which are predictable from diode to diode comprising:
- a substrate including terminals connectable to a source of regulated DC potential;
- a voltage divider network, coupled to said terminals, including a plurality of resistors formed on said substrate and having junctions corresponding to different ones of said television channel signals;
- a plurality of channel switch contacts formed on said substrate, each coupled to a respective one of said junctions;
- a channel wiper movably mounted on said substrate for sequentially connecting said channel switch contacts to the tuner;
- and
- setting means interposed between said terminals and said voltage divider network for adjusting the tuning voltage of an end junction of said network to correspond to a limit television channel signal in said range.
Dependencies are inferred from the claim text.