US3563492A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Capstan acceleration control system for wideband instrumentation magnetic tape transports
Assignee: Ampex Corp
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Filing: 1969-09-10
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Granted: 1971-02-16
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Expires: 1989-09-10
Abstract
Abstract A system for controlling capstan acceleration to prevent the tape loops from pulling out of or bottoming in the vacuum chambers during extreme speed change modes such as stop, start, and fast wind. The system is particularly applicable where relatively small, low power supply and takeup reel motors, and relatively short vacuum chambers are employed in conjunction with a low inertia, high acceleration, capstan system capable of detrimentally altering tape loop position in the vacuum chambers before the reel servos can effect equalization.
Inventors
- 👤 Herman A Ferrier Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 13:46
CPC Classifications
G; G11; G11B; G11B15/00; G11B15/18; G11B15/46; G11B15/48; G11B15/56; G11B15/58
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
336 words
In a magnetic tape transport of the type including tape supply and takeup reels, capstan means for controlling the movement of tape past record and reproducing means intermediate said supply and takeup reels, a pair of vacuum chambers respectively disposed between said capstan means and said supply and takeup reels, said tape extending into said vacuum chambers in the form of variable length open loops, supply and takeup reel motors coupled in driving relation to said supply and takeup reels, tape loop position-sensing means associated with each of said chambers for developing signals representative of the position of said tape loop therein, a tape loop position error detector coupled to each of said loop position-sensing means for developing a bipolar loop position error signal indicative of displacements of said loop from the center of said chamber, reel servo means respectively coupled to said loop position error detectors and to said reel motors to control the rotations of said supply and takeup reels in compensatory relation to said loop position error signals, a capstan motor coupled in driving relation to said capstan means, a capstan motor drive amplifier coupled in energizing relation to said capstan motor, and capstan servo equalizer means coupled to said capstan motor drive amplifier for applying a capstan error signal thereto to control the rotation of said capstan means in compensating relation to said capstan error signal, a capstan acceleration control system comprising a pair of negative feedback paths respectively coupled between said tape loop position error detectors and said capstan motor drive amplifier, means within each of said feedback paths for establishing a transfer characteristic having a dead zone extending between predetermined limits of said loop position error signals, and combining means within said feedback paths for combining said loop position error signals and said capstan error signal for application to said capstan motor drive amplifier, said loop position error signals applied to said combining means to control the acceleration of the capstan in compensating relation to said loop position error signals.
Claim 2
Dependent Claim
336 words
In a magnetic tape transport of the type including tape supply and takeup reels, capstan means for controlling the movement of tape past record and reproducing means intermediate said supply and takeup reels, a pair of vacuum chambers respectively disposed between said capstan means and said supply and takeup reels, said tape extending into said vacuum chambers in the form of variable length open loops, supply and takeup reel motors coupled in driving relation to said supply and takeup reels, tape loop position-sensing means associated with each of said chambers for developing signals representative of the position of said tape loop therein, a tape loop position error detector coupled to each of said loop position-sensing means for developing a bipolar loop position error signal indicative of displacements of said loop from the center of said chamber, reel servo means respectively coupled to said loop position error detectors and to said reel motors to control the rotations of said supply and takeup reels in compensatory relation to said loop position error signals, a capstan motor coupled in driving relation to said capstan means, a capstan motor drive amplifier coupled in energizing relation to said capstan motor, and capstan servo equalizer means coupled to said capstan motor drive amplifier for applying a capstan error signal thereto to control the rotation of said capstan means in compensating relation to said capstan error signal, a capstan acceleration control system comprising a pair of negative feedback paths respectively coupled between said tape loop position error detectors and said capstan motor drive amplifier, means within each of said feedback paths for establishing a transfer characteristic having a dead zone extending between predetermined limits of said loop position error signals, and combining means within said feedback paths for combining said loop position error signals and said capstan error signal for application to said capstan motor drive amplifier, said loop position error signals applied to said combining means to control the acceleration of the capstan in compensating relation to said loop position error signals.
Claim 3
Dependent Claim
40 words
The combination of claim 1 wherein said loop position error signals and said capstan error signal are applied to said capstan motor drive in relative proportions to override said capstan error signal with one of said loop position error signals.
Claim 4
Dependent Claim
41 words
The combination of claim 2, further defined by said means within each of said feedback paths for establishing a transfer characteristic having a dead zone including a bipolar breakdown discharge device having a negligible output over a range of bipolar inputs.
Claim 5
Dependent Claim
16 words
The combination of claim 3, further defined by said discharge device beiNg a bipolar Zener diode.
Claim 6
Dependent Claim
80 words
The combination of claim 2, further defined by said means within each of said feedback paths for establishing a transfer characteristic either a dead zone comprising a bipolar Zener diode coupled to each of said loop position error detectors, a pair of parallel back-to-back crystal diodes connected between said Zener diode and said combining means, and a resistor connected at one end to the common junction of said Zener diode and crystal diodes and at the other end to ground.
Claim 7
Dependent Claim
96 words
The combination of claim 2, further defined by said combining means comprising an operational amplifier and a resistor connected between the output and an input of said operational amplifier, second and third resistors respectively coupling the transfer characteristic establishing means in said feedback paths to said input of said operational amplifier, and a fourth resistor coupling said capstan servo equalizer means to said input of said operational amplifier, said second and third resistors having small resistances relative to that of said first resistor, said fourth resistor having a resistance comparable to that of said first resistor.
Claim 8
Dependent Claim
139 words
The combination of claim 6, further defined by said means within said feedback paths for establishing transfer characteristics having dead zones comprising a bipolar Zener diode coupled to a first of said loop position error detectors, a pair of parallel back-to-back crystal diodes connected between said Zener diode and said second resistor, a fifth resistor connected at one end to the common junction between said Zener diode and crystal diodes and at the other end to ground, a second bipolar Zener diode coupled to a second of said loop position error detectors, a second pair of parallel back-to-back crystal diodes connected between said second Zener diode and said third resistor, and a sixth resistor connected at one end to the common junction between said second Zener diode and second pair of crystal diodes and at other end to ground.
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) | 1974-02-15 | 1974-08-17 | 1975-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-15 | 1978-08-17 | 1979-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-15 | 1982-08-17 | 1983-02-16 | $7700.00 | Window Closed / Lapsed |