US3593154A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Frequency-selective coupling network for a television tuner
Assignee: Zenith Electronics LLC
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Filing: 1969-01-28
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Granted: 1971-07-13
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Expires: 1989-01-28
Abstract
Abstract Tuning to a desired television channel, while rejecting its image channel, is accomplished by a novel coupling network combining a frequency selector and an image rejection trap simultaneously tunable to different frequencies by means of a single common tuning element. By the adjustment of a variable air capacitor, shunt connected to the primary inductor of a transformer, the frequency selector may be tuned to maximize the response of the coupling network to a selected television channel. The image rejection trap is formed by the mutual inductance and capacity coupling between the primary inductor and a secondary inductor of the transformer. Variations of the air capacitor effect changes in the coefficient of capacitive coupling between the inductors, with the result that the trap tracks the frequency selector; namely, as the frequency selector is tuned to a different selected channel the trap is automatically tuned to that channel''s image frequency to achieve image signal suppression.
Inventors
- 👤 David A Blass
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 11:14
CPC Classifications
H; H03; H03D; H03D7/00; H03D7/18
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
319 words
A frequency-selective coupling network for use in a superheterodyne television tuner for selecting a predetermined television channel for conversion into a desired intermediate frequency signal and for rejecting the image channel of said predetermined channel displaced in frequency above said predetermined channel, said coupling network comprising: a tunable frequency selector comprising a first inductor and a second inductor disposed adjacent thereto and establishing a mutual inductance therebetween for translating a component of signal energy at the frequency of said predetermined selected channel and for translating a component of signal energy at the frequency of said image channel, said first and second inductors further establishing a relatively fixed capacitance therebetween for effecting a capacitive coupling between said inductors for translating a component of signal energy at the frequency of said predetermined channel and also for translating a component of signal energy at the frequency of said image channel, an adjustable tuning capacitor shunted across said first inductor for resonating said first inductor to maximize the response of said coupling network to said predetermined channel, one terminal of said tuning capacitor and one terminal of said first inductor establishing a common terminal; a tunable image channel rejection trap comprised of said second inductor and said coupling capacitance effectively arranged in series and coupled across at least a portion of said first inductor; a load circuit comprising a heterodyning device coupled between the effective juncture of said second inductor and said coupling capacitance and said common terminal; and means for adjusting said tuning capacitor to permit said frequency selector to select any television channel within the range of said tuner while simultaneously varying the effective capacitance coupling between said inductors so that the resultant image frequency energy component appearing at the effective juncture of the second inductor and said coupling capacitance is minimized and substantially only signal energy at the frequency of said predetermined selected channel is applied to said heterodyning device.
Claim 2
Dependent Claim
319 words
A frequency-selective coupling network for use in a superheterodyne television tuner for selecting a predetermined television channel for conversion into a desired intermediate frequency signal and for rejecting the image channel of said predetermined channel displaced in frequency above said predetermined channel, said coupling network comprising: a tunable frequency selector comprising a first inductor and a second inductor disposed adjacent thereto and establishing a mutual inductance therebetween for translating a component of signal energy at the frequency of said predetermined selected channel and for translating a component of signal energy at the frequency of said image channel, said first and second inductors further establishing a relatively fixed capacitance therebetween for effecting a capacitive coupling between said inductors for translating a component of signal energy at the frequency of said predetermined channel and also for translating a component of signal energy at the frequency of said image channel, an adjustable tuning capacitor shunted across said first inductor for resonating said first inductor to maximize the response of said coupling network to said predetermined channel, one terminal of said tuning capacitor and one terminal of said first inductor establishing a common terminal; a tunable image channel rejection trap comprised of said second inductor and said coupling capacitance effectively arranged in series and coupled across at least a portion of said first inductor; a load circuit comprising a heterodyning device coupled between the effective juncture of said second inductor and said coupling capacitance and said common terminal; and means for adjusting said tuning capacitor to permit said frequency selector to select any television channel within the range of said tuner while simultaneously varying the effective capacitance coupling between said inductors so that the resultant image frequency energy component appearing at the effective juncture of the second inductor and said coupling capacitance is minimized and substantially only signal energy at the frequency of said predetermined selected channel is applied to said heterodyning device.
Claim 3
Dependent Claim
41 words
A frequency-selective coupling network according to claim 1 in which said first inductor is a coil having a plurality of winding turns and in which at least a portion of said second inductor lies between adjacent ones of said winding turns.
Claim 4
Dependent Claim
20 words
A frequency-selective coupling network according to claim 2 in which said portion of said second inductor constitutes a coupling loop.
Claim 5
Dependent Claim
34 words
A frequency-selective coupling network according to claim 2 in which one extremity of said second inductor is connected to one of said winding turns, while the other extremity is connected to said heterodyning device.
Claim 6
Dependent Claim
16 words
A frequency-selective coupling network according to claim 1 in which said heterodyning device comprises a diode.
Claim 7
Dependent Claim
45 words
A frequency-selective coupling network according to claim 1 in which said tuner is a UHF tuner with said frequency selector and said image rejection trap are enclosed within a compartment, and in which said frequency selector is tunable to any channel in the UHF band.
Claim 8
Dependent Claim
69 words
A frequency-selective coupling network according to claim 1 in which said first inductor is a coil having a plurality of winding turns, wherein one terminal of said second inductor is coupled to one of said winding turns at one end of said first inductor, and in which a portion of said second inductor lies between adjacent ones of said winding turns at the other end of said first inductor.
Claim 9
Dependent Claim
44 words
A frequency-selective coupling network according to claim 1 in which said first inductor constitutes an autotransformer having a tap thereon connected to one extremity of said second inductor, and in which the other extremity of said second inductor is connected to said heterodyning device.
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) | 1974-07-12 | 1975-01-11 | 1975-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-07-12 | 1979-01-11 | 1979-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-07-12 | 1983-01-11 | 1983-07-13 | $7700.00 | Window Closed / Lapsed |