US3750028A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tuning system
Assignee: Panasonic Holdings Corp
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Filing: 1971-06-21
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Granted: 1973-07-31
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Expires: 1991-06-21
Abstract
Abstract A tuning system comprising a tuning circuit for selecting a channel, by the impedance of a variable capacitance diode, a power supply for generating a tuning voltage, and an AFT circuit for generating an AFT (automatic fine tuning) voltage. The power supply and the AFT circuit are connected in parallel with each other so that the tuning voltage and the AFT voltage are superimposed one on the other and applied to one of the terminals of the variable capacitance diode, while the other terminal of the variable capacitance diode may be grounded in order to check the increase in floating capacitance and tune in, to a wide range of frequencies.
Inventors
- 👤 K Uchida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:37
CPC Classifications
H; H03; H03J; H03J7/00; H03J7/02; H03J7/04; H03J7/08; H03J7/10; H03J5/00; H03J5/02; H03J5/0209; H03J7/12
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
219 words
Apparatus for maintaining the sensitivity of a multifrequency tuning circuit uniform over a wide range of received frequencies, comprising: a voltage source; a tuning voltage selecting circuit coupled to said voltage source for selecting a tuning voltage corresponding to a desired channel frequency; an automatic fine tuning circuit for providing a corresponding fine tuning voltage; a main tuning circuit, including at least one variable capacitance diode, said main tuning circuit being tuned to said desired channel frequency in correspondence with the impedance of said variable capacitance diode; a first resistance circuit coupled to the output of said tuning voltage selecting circuit; a second resistance circuit coupled to the output of said automatic fine tuning circuit; said first and second resistance circuits being coupled to each other at their respective outputs so that the output of each resistance circuit is superimposed onto that of the other, the coupled outputs of said first and second resistance circuits being coupled to the input of said main tuning circuit; and means for adjusting the ratio of the composite impedance of said tuning voltage selecting circuit and said first resistance circuit to the composite impedance of said automatic fine tuning circuit and said second resistance circuit to thereby maintain the sensitivity of said tuning circuit uniform over a predetermined range of desired channel frequencies.
Claim 2
Dependent Claim
219 words
Apparatus for maintaining the sensitivity of a multifrequency tuning circuit uniform over a wide range of received frequencies, comprising: a voltage source; a tuning voltage selecting circuit coupled to said voltage source for selecting a tuning voltage corresponding to a desired channel frequency; an automatic fine tuning circuit for providing a corresponding fine tuning voltage; a main tuning circuit, including at least one variable capacitance diode, said main tuning circuit being tuned to said desired channel frequency in correspondence with the impedance of said variable capacitance diode; a first resistance circuit coupled to the output of said tuning voltage selecting circuit; a second resistance circuit coupled to the output of said automatic fine tuning circuit; said first and second resistance circuits being coupled to each other at their respective outputs so that the output of each resistance circuit is superimposed onto that of the other, the coupled outputs of said first and second resistance circuits being coupled to the input of said main tuning circuit; and means for adjusting the ratio of the composite impedance of said tuning voltage selecting circuit and said first resistance circuit to the composite impedance of said automatic fine tuning circuit and said second resistance circuit to thereby maintain the sensitivity of said tuning circuit uniform over a predetermined range of desired channel frequencies.
Claim 3
Dependent Claim
23 words
The apparatus according to claim 1, wherein said second resistance circuit has a resistance value higher than that of said first resistance circuit.
Claim 4
Dependent Claim
73 words
The apparatus according to claim 1, wherein one of said first and second resistance circuits comprises one fixed resistor, the other comprising variable resistance means, the resistance value of said variable resistance means being varied in response to the operation of said tuning voltage selecting circuit, whereby the ratio of the superimposed automatic fine tuning voltage applied to one terminal of said variable capacitance diode is changed and the sensitivity is made uniform.
Claim 5
Dependent Claim
245 words
Apparatus for maintaining the sensitivity of a multi-frequency television receiver tuning circuit uniform over a wide range of received frequencies, comprising: a voltage source; a tuning voltage selecting circuit including voltage dividing resistance means coupled to said voltage source for selecting a tuning voltage corresponding to a desired channel frequency; an automatic fine tuning circuit for providing a corresponding fine tuning voltage, said automatic fine tuning circuit including means for frequency discriminating video intermediate frequency carriers of the received television signal; a main tuning circuit, including at least one variable capacitance diode, said main tuning circuit being tuned to said desired channel frequency in correspondence with the impedance of said variable capacitance diode; a first resistance circuit coupled to the output of said tuning voltage selecting circuit; a second resistance circuit coupled to the output of said automatic fine tuning circuit; said first and second resistance circuits being coupled to each other at their respective outputs so that the output of each resistance circuit is superimposed onto that of the other, the coupled outputs of said first and second resistance circuits being coupled to the input of said main tuning circuits; and means for adjusting the ratio of the composite impedance of said tuning voltage selecting circuit and said first resistance circuit to the composite impedance of said automatic fine tuning circuit and said second resistance circuit to thereby maintain the sensitivity of said tuning circuit uniform over a predetermined range of desired channel frequencies.
Claim 6
Dependent Claim
245 words
Apparatus for maintaining the sensitivity of a multi-frequency television receiver tuning circuit uniform over a wide range of received frequencies, comprising: a voltage source; a tuning voltage selecting circuit including voltage dividing resistance means coupled to said voltage source for selecting a tuning voltage corresponding to a desired channel frequency; an automatic fine tuning circuit for providing a corresponding fine tuning voltage, said automatic fine tuning circuit including means for frequency discriminating video intermediate frequency carriers of the received television signal; a main tuning circuit, including at least one variable capacitance diode, said main tuning circuit being tuned to said desired channel frequency in correspondence with the impedance of said variable capacitance diode; a first resistance circuit coupled to the output of said tuning voltage selecting circuit; a second resistance circuit coupled to the output of said automatic fine tuning circuit; said first and second resistance circuits being coupled to each other at their respective outputs so that the output of each resistance circuit is superimposed onto that of the other, the coupled outputs of said first and second resistance circuits being coupled to the input of said main tuning circuits; and means for adjusting the ratio of the composite impedance of said tuning voltage selecting circuit and said first resistance circuit to the composite impedance of said automatic fine tuning circuit and said second resistance circuit to thereby maintain the sensitivity of said tuning circuit uniform over a predetermined range of desired channel frequencies.
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) | 1976-07-30 | 1977-01-29 | 1977-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-30 | 1981-01-29 | 1981-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-30 | 1985-01-29 | 1985-07-31 | $7700.00 | Window Closed / Lapsed |