US3971991A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Television tuning system with varactor malfunction detection
Assignee: Zenith Electronics LLC
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Filing: 1974-09-04
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Granted: 1976-07-27
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Expires: 1994-09-04
Abstract
Abstract An all channel television varactor diode tuning system has a presettable counter for deriving the number of the receivable television channel by counting pulses indicative of the tuner local oscillator frequency, which is varied by a voltage ramp circuit under the control of a comparator. The derived channel number is supplied to one input of the comparator, and a channel number selector supplies an encoded desired channel number to the other comparator input and to a frequency band decoder. The band decoder supplies signals to establish appropriate preset counts for the counter in accordance with the frequency band. Malfunction detection circuitry for detecting an improper number of pulses for the presettable counter, when in the low VHF frequency bands, is coupled to the channel number selector and connected through the comparator to force the tuning voltage circuit to drive the varactor in a direction opposite to that indicated by the comparator. This is done by monitoring the tens digit in the counter for occurrence of an 8 or 9.
Inventors
- 👤 Akio Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:16
CPC Classifications
H; H03; H03J; H03J5/00; H03J5/02; H03J5/0245; H03J7/00; H03J7/18; H03J7/20; H03J7/28
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
146 words
A television tuning control system comprising: a tuner having a varactor diode tuning element operating in several predetermined discrete frequency bands containing a plurality of fixed bandwidth signals indentified by assigned channel numbers; tuning frequency counting means, employing preset counts corresponding to said frequency bands and sampling the frequency of said varactor diode tuning element, for deriving from the frequency of said tunable element, information indicative of the channel number of the corresponding receivable television channel; channel number selection means; comparison means coupled between said tuning frequency counting means and said channel number selection means for comparing desired channel number information from said channel number selection means with derived channel number information from said tuning frequency counting means; tuning voltage means coupled between said varactor diode tuning element and said comparison means, for driving said tuning element to change frequency in response to said comparison means;
Claim 2
Dependent Claim
146 words
A television tuning control system comprising: a tuner having a varactor diode tuning element operating in several predetermined discrete frequency bands containing a plurality of fixed bandwidth signals indentified by assigned channel numbers; tuning frequency counting means, employing preset counts corresponding to said frequency bands and sampling the frequency of said varactor diode tuning element, for deriving from the frequency of said tunable element, information indicative of the channel number of the corresponding receivable television channel; channel number selection means; comparison means coupled between said tuning frequency counting means and said channel number selection means for comparing desired channel number information from said channel number selection means with derived channel number information from said tuning frequency counting means; tuning voltage means coupled between said varactor diode tuning element and said comparison means, for driving said tuning element to change frequency in response to said comparison means;
Claim 3
Dependent Claim
93 words
channel band determination means coupled between said channel number selection means and said tuning frequency counting means for segregating selected channel numbers according to their location in said several predetermined discrete frequency bands and establishing said preset counts for said tuning frequency counting means; and malfunction detection means coupled between said counting means and said tuning voltage means for detecting an improper number of pulses from said counting means and forcing said tuning voltage means to drive said varactor diodes tuning element in a direction opposite to that indicated by said comparison means.
Claim 4
Dependent Claim
93 words
channel band determination means coupled between said channel number selection means and said tuning frequency counting means for segregating selected channel numbers according to their location in said several predetermined discrete frequency bands and establishing said preset counts for said tuning frequency counting means; and malfunction detection means coupled between said counting means and said tuning voltage means for detecting an improper number of pulses from said counting means and forcing said tuning voltage means to drive said varactor diodes tuning element in a direction opposite to that indicated by said comparison means.
Claim 5
Dependent Claim
41 words
The television tuning control system of claim 1 wherein said malfunction detection means is also coupled to an output of said channel band determination means and enabled by said channel band determination means only for certain of said discrete frequency bands.
Claim 6
Dependent Claim
38 words
The television tuning control system of claim 2 wherein said improper number of pulses results from the occurrence of a low voltage condition for said varactor diode when in the first or lowest of said discrete frequency bands.
Claim 7
Dependent Claim
28 words
The television tuning control system of claim 3 wherein said malfunction detection means determines when said tuning frequency counting means has been advanced sufficiently beyond its preset value.
Claim 8
Dependent Claim
45 words
The television tuning control system of claim 4 wherein said channel number selection means includes means for binary encoding the individual digits of two digit channel numbers, and said malfunction detection means is responsive to one of said individual digits of the derived channel number.
Claim 9
Dependent Claim
24 words
The television tuning control system of claim 5 wherein said malfunction detection means is responsive to the tens digit of said derived channel number.
Claim 10
Dependent Claim
32 words
The television tuning control system of claim 6 wherein said malfunction detection means is responsive only to the highest order bit of said binary encoded tens digit of the derived channel number.
Claim 11
Dependent Claim
35 words
The television tuning control system of claim 7 wherein said malfunction detection means determines equality between the said highest order bit of said binary encoded tens digit and the corresponding bit of the preset count.
Claim 12
Dependent Claim
59 words
The television tuning control system of claim 8 wherein said comparison means includes a ramp increase and a ramp decrease output corresponding respectively to the comparison conditions for increasing and decreasing the frequency of said tunable element and said malfunction detection means includes logic means interconnected with said ouputs for overriding the normal signals generated by said comparison means.
Claim 13
Dependent Claim
91 words
The television tuning control system of claim 9 wherein said malfunction detection means comprises: a first AND gate accepting a signal indicative of the selection of a first band channel and a signal representing said highest order bit of said tens digit of a derived channel number, a second AND gate accepting an inverted signal from said first AND gate and a ramp decrease signal from said comparison means, said first and second AND gates being interconnected with said comparison means to override the normal signals generated by said comparison means.
Claim 14
Dependent Claim
107 words
The television tuning control system of claim 10 wherein said malfunction detection means further comprises: an OR gate accepting the output of said first AND gate and a ramp increase signal from the tens digit section of said comparison means, and wherein said second AND gate accepts an inverted signal from said first AND gate and a ramp decrease signal from the tens digit section of said comparison means, said first and second AND gates being interconnected with said comparison means to inhibit the generation of the normal tens section ramp decrease signal with the output of said OR gate supplying the tens section ramp increase signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-07-27 | 1980-01-26 | 1980-07-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-07-27 | 1984-01-26 | 1984-07-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-07-27 | 1988-01-26 | 1988-07-27 | $7700.00 | Window Closed / Lapsed |