US3813615A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Local oscillator for television tuner having reduced oscillation voltage variation between high and low frequency bands
Assignee: Alps Alpine Co Ltd
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Filing: 1973-07-13
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Granted: 1974-05-28
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Expires: 1993-07-13
Abstract
Abstract A local oscillator circuit for a television tuner or the like includes a transistor and an oscillatory circuit connected thereto. Selector means are connected to the oscillatory circuit to cause the oscillatory circuit to operate at low and high band frequencies respectively. Separate biasing means are provided to bias the transistor at first and second voltage levels respectively, and bias control means are connected to the selector means to connect the appropriate biasing means to the transistor when the selector means adapts the oscillatory circuit to operate at a high band or a low band frequency. The bias control means comprises a switching diode connected between ground and the dividing point of high and low frequency band coils of the oscillatory circuit. A negative voltage source is connected through a high resistance to an end of the low band coil. The selector means comprises a switch controlled by the channel selector shaft of the tuner and is disposed between the end of the low band coil and a power source to control the switching diode such that the transistor bias voltage is regulated in accordance with the mode of operation of the circuit.
Inventors
- 👤 M Okazaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 04:55
CPC Classifications
H; H03; H03J; H03J5/00; H03J5/24; H03J5/242; H03J5/244; H03B; H03B5/00; H03B5/08; H03B5/12; H03B5/1203; H03B5/1231; H03B5/1237; H03B5/124; H03B5/1243; H03B5/1262; H03B2200/00; H03B2200/003; H03B2200/004; H03B2200/0048; H03B2200/0056; H03B2201/00; H03B2201/02; H03B2201/0208
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
125 words
A local oscillator circuit for a television tuner or the like comprising a transistor and an oscillatory circuit operatively connected thereto, selector means operatively connected to said oscillatory circuit and active to cause said circuit to operate in first and second frequency bands respectively, first and second biasing means adapted to be operatively connected to said transistor to bias the latter at first and second voltage levels respectively, and bias control means operatively connected to said selector means and effective to connect said first and second biasing means respectively to said transistor when said selector means adapts said oscillatory circuit to operate in said first and second frequency bands respectively, thereby to minimize variations in oscillator output amplitude as between one band and the other.
Claim 2
Dependent Claim
125 words
A local oscillator circuit for a television tuner or the like comprising a transistor and an oscillatory circuit operatively connected thereto, selector means operatively connected to said oscillatory circuit and active to cause said circuit to operate in first and second frequency bands respectively, first and second biasing means adapted to be operatively connected to said transistor to bias the latter at first and second voltage levels respectively, and bias control means operatively connected to said selector means and effective to connect said first and second biasing means respectively to said transistor when said selector means adapts said oscillatory circuit to operate in said first and second frequency bands respectively, thereby to minimize variations in oscillator output amplitude as between one band and the other.
Claim 3
Dependent Claim
28 words
The circuit of claim 1 wherein said oscillatory circuit comprises a low band inductance coil and a high band inductance coil, said coils being connected through a node.
Claim 4
Dependent Claim
34 words
The circuit of claim 2 wherein said bias control means comprises a diode operably connected between said node and ground, and means for biasing said diode between a conducting state and a nonconducting state.
Claim 5
Dependent Claim
48 words
The circuit of claim 3 wherein said diode biasing means comprises a negative voltage source operably connected to the end of said low band inductance coil other than the end connected to said node and a high resistance interposed between said source and said lOw band inductance coil.
Claim 6
Dependent Claim
26 words
The circuit of claim 4 wherein said selector means comprises a switch operably connected between said end of said low band inductance coil and said transistor.
Claim 7
Dependent Claim
26 words
The circuit of claim 5 further comprising a rotatable channel selector shaft, the switch being opened or closed in accordance with the rotation of said shaft.
Claim 8
Dependent Claim
17 words
The circuit of claim 5 wherein said input current of said transistor is controlled by said switch.
Claim 9
Dependent Claim
17 words
The circuit of claim 3 wherein the base of said transistor is operably connected to said diode.
Claim 10
Dependent Claim
40 words
The circuit of claim 1 further comprising a power source, a first and a second resistor connected in series between said said power source and ground, the base of said transistor being operably connected between said first and second resistors.
Claim 11
Dependent Claim
39 words
The circuit of claim 3 further comprising a power source and wherein said regulating means comprises a resistor for biasing the collector of said transistor, said resistor being connected between said power source and the collector of said transistor.
Claim 12
Dependent Claim
33 words
The circuit of claim 10 wherein said diode is operably connected between said biasing resistor and the collector of said transistor such that said biasing resistor is bypassed when said diode is conducting.
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) | 1977-05-27 | 1977-11-26 | 1978-05-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-27 | 1981-11-26 | 1982-05-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-27 | 1985-11-26 | 1986-05-28 | $7700.00 | Window Closed / Lapsed |