Patent US3852813A successfully refreshed from Google Patents.
US3852813A
Expired / Lapsed
US
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Method and circuit for recording audio signals on magnetic tape
Assignee: Polaroid Corp
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Filing: 1972-09-11
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Granted: 1974-12-03
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Expires: 1992-09-11
Abstract
Abstract A method and circuit for recording an audio signal on magnetic tape wherein a bias signal in the form of a square wave is superimposed upon the audio signal before the latter is fed to a magnetic head for recording to cause the audio signal to operate on a linear portion of the transfer characteristic curve for the tape.
Inventors
- 👤 C Petersen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 14:26
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/02; G11B5/027; G11B5/03
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
120 words
Recording apparatus of a low package volume variety comprising: speaker-microphone means having a record mode for receiving an audio signal and having an output corresponding thereto; amplifier means connected to said speaker-microphone for amplifying said output; means coupled between the input and output of said amplifier means providing automatic gain control over said amplifier means when said speaker-microphone is in said record mode; free-running multivibrator means having an output generatinG a bias signal having a repeating, symmetrical, substantially rectangular wave form; a magnetic recording head; circuit means for amplitude summing said bias signal with said amplified output and applying said summated signal to said recording head, said bias signal being selected to cause said audio signal to be recorded linearly.
Claim 2
Dependent Claim
120 words
Recording apparatus of a low package volume variety comprising: speaker-microphone means having a record mode for receiving an audio signal and having an output corresponding thereto; amplifier means connected to said speaker-microphone for amplifying said output; means coupled between the input and output of said amplifier means providing automatic gain control over said amplifier means when said speaker-microphone is in said record mode; free-running multivibrator means having an output generatinG a bias signal having a repeating, symmetrical, substantially rectangular wave form; a magnetic recording head; circuit means for amplitude summing said bias signal with said amplified output and applying said summated signal to said recording head, said bias signal being selected to cause said audio signal to be recorded linearly.
Claim 3
Dependent Claim
30 words
The recording apparatus of claim 1 in which said amplifier means, said automatic gain control means, said free-running multiibrator means and said circuit means are fabricated as an integrated circuit.
Claim 4
Dependent Claim
35 words
The recording apparatus of claim 1 further including resistor means within said circuit means intermediate said amplifier means output and the output of said multivibrator means for presenting a high impedance to said bias signal.
Claim 5
Dependent Claim
43 words
The recording apparatus of claim 3 further including capacitor means within said circuit means intermediate said multivibrator means output and said recording head for providing a low impedance to said bias signal and a high impedance to the output of said amplifier means.
Claim 6
Dependent Claim
56 words
The recording apparatus of claim 1 further including switching means connected with said circuit means and having one orientation for operating said apparatus in said record mode and switchable to another orientation to electrically couple said recording head with the input of said amplifier means and the output of said amplifier means with said speaker-microphone means.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-02 | 1978-06-03 | 1978-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-02 | 1982-06-03 | 1982-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-02 | 1986-06-03 | 1986-12-03 | $7700.00 | Window Closed / Lapsed |