Telecommunications – Receiver or analog modulated signal frequency converter – Signal selection based on frequency
Patent
1980-05-29
1984-08-14
Chin, Tommy P.
Telecommunications
Receiver or analog modulated signal frequency converter
Signal selection based on frequency
455195, 455217, H03J 708, H04B 116
Patent
active
044661266
ABSTRACT:
A television tuner comprises a tuning circuit including a voltage controlled variable capacitance diode. The tuning circuit is housed within a shield casing. The shield casing is provided with a terminal for electrical connection to the variable capacitance diode and the terminal is supplied with a tuning voltage from a channel selecting apparatus. A Zener diode is connected between the tuning voltage terminal and the shield casing, whereby the upper limit of the tuning voltage being applied to the variable capacitance diode is restricted. A predetermined voltage determinable dependent on the Zener diode is selected such that the tuning frequency established by the tuning circuit when the predetermined voltage is applied to the variable capacitance diode may be a predetermined upper limit frequency of a desired receiving frequency band. The lower limit of the tuning voltage is also restricted so as not to become lower than a predetermined voltage. Accordingly, the tuning frequency is prevented from being changed toward a higher or lower frequency deviating from the corresponding variation range of the desired receiving frequency band.
REFERENCES:
patent: 3559076 (1971-01-01), Worcester
patent: 3639840 (1972-02-01), Shekel
patent: 3828257 (1974-08-01), Puskas
patent: 3965427 (1976-06-01), Ma
patent: 3968440 (1976-07-01), Ehni
patent: 4081752 (1978-03-01), Sumi
patent: 4110693 (1978-08-01), Evans
patent: 4137502 (1979-01-01), Maddaloni
patent: 4189678 (1980-02-01), Sakamoto
A System Approach to Low-Cost Electronic Tuning Address, by Howell, IEEE Transactions on Consumer Electronics, vol. CE-24, No. 3, 8/78, pp. 408-416.
Chin Tommy P.
Sanyo Electric Co,. Ltd.
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