US3721882A
Expired / Lapsed
US
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Positioning system
Assignee: Unisys Corp
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Filing: 1971-06-25
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Granted: 1973-03-20
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Expires: 1991-06-25
Abstract
Abstract A system useful in a magnetic disc storage unit for rapidly and accurately positioning a magnetic head over a selected disc track. The system includes a linear motor for driving a carriage structure supporting a head carrying arm assembly. The motor is selectively energized by a control unit in response to new track command information provided thereto. The control unit includes a velocity transducer for yielding carriage velocity information and a displacement transducer for yielding track count information. A counter, responsive to said track count information, at all times stores a count representative of the actual head track position for comparison with the track command information. The difference between the actual head track position and command track position determines the magnitude of velocity command signal introduced into a velocity servo loop for driving the motor. As the difference decreases, the velocity command signal magnitude is reduced to progressively reduce motor velocity. When the difference reaches a predetermined small value (e.g., zero), the velocity command signal is reduced to zero and a position servo loop, responsive to information provided by the displacement transducer, is enabled to bring the carriage to rest in a position at which the error signal provided by the displacement transducer to the position servo loop is nulled.
Inventors
- 👤 C Helms
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 20:42
CPC Classifications
G; G05; G05D; G05D3/00; G05D3/12; G05D3/14; G05D3/1445; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/19; G05B19/21; G05B19/23; G05B19/231; G05B19/232; G05B19/39; G11; G11B; G11B5/00; G11B5/48; G11B5/54; G11B5/55; G11B5/5521; G11B5/5526; G11B5/553; G11B5/5547; G11B5/5552; G11B5/5556; G05B2219/00; G05B2219/30; G05B2219/42; G05B2219/42114; G05B2219/43; G05B2219/43179
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
285 words
A system for rapidly and accurately positioning a carriage juxtaposed a desired location on a memory device, said system comprising: a carriage, drive means connected to the carriage for imparting movement thereto, amplifier means for actuating said drive means, said amplifier means having an input for receiving a plurality of input signals, address register means identifying a desired carriage position, counter means identifying an actual position of said carriage, arithmetic means for producing a plurality of signals indicative of direction and of the difference between the desired carriage position and the actual carriage position, velocity decoder means connected to said arithmetic means for producing a plurality of input signals proportional to the difference between the desired and the actual carriage position, said velocity decoder means being connected through a normally closed switch to said input of said amplifier means, tachometer feedback means coupled to said carriage and providing an input signal at said input of said amplifier means proportional to the velocity of said carriage, displacement transducer means coupled to said carriage and providing a plurality of output signals, at least one output signal being connected to said counter means and another output signal being connected through a normally open switch to said input of said amplifier means and having a voltage change characteristic which coincides with the exact center location of the memory device, and switch means actuated by said arithmetic means when the carriage approaches the desired position, said switch means being connected to open said normally closed switch and to close said normally open switch whereby said drive means is controlled to a final position by an input signal from said tachometer feedback means and an output signal from said displacement transducer.
Claim 2
Independent Claim
285 words
A system for rapidly and accurately positioning a carriage juxtaposed a desired location on a memory device, said system comprising: a carriage, drive means connected to the carriage for imparting movement thereto, amplifier means for actuating said drive means, said amplifier means having an input for receiving a plurality of input signals, address register means identifying a desired carriage position, counter means identifying an actual position of said carriage, arithmetic means for producing a plurality of signals indicative of direction and of the difference between the desired carriage position and the actual carriage position, velocity decoder means connected to said arithmetic means for producing a plurality of input signals proportional to the difference between the desired and the actual carriage position, said velocity decoder means being connected through a normally closed switch to said input of said amplifier means, tachometer feedback means coupled to said carriage and providing an input signal at said input of said amplifier means proportional to the velocity of said carriage, displacement transducer means coupled to said carriage and providing a plurality of output signals, at least one output signal being connected to said counter means and another output signal being connected through a normally open switch to said input of said amplifier means and having a voltage change characteristic which coincides with the exact center location of the memory device, and switch means actuated by said arithmetic means when the carriage approaches the desired position, said switch means being connected to open said normally closed switch and to close said normally open switch whereby said drive means is controlled to a final position by an input signal from said tachometer feedback means and an output signal from said displacement transducer.
Claim 3
Dependent Claim
47 words
A system for rapidly and accurately positioning a carriage as set forth in claim 1 which further includes direction indicating means connected to said velocity decoder means and said arithmetic means, said direction indicating means being capable of directing said drive means in a plurality of directions.
Claim 4
Dependent Claim
39 words
A system for rapidly and accurately positioning a carriage as set forth in claim 2 wherein said tachometer feedback means produces an input signal which is opposite in polarity to the input signal produced by said velocity decoder means.
Claim 5
Dependent Claim
45 words
A system for Rapidly and accurately positioning a carriage as set forth in claim 3 wherein said tachometer feedback means supplies an input signal which is effective to brake or retard the direction of carriage movement when said switch means opens said normally closed switch.
Claim 6
Dependent Claim
37 words
A system for rapidly and accurately positioning a carriage as set forth in claim 1 wherein said voltage change characteristic comprises a slope shape which passes through zero coincident with the exact location of said memory device.
Claim 7
Dependent Claim
23 words
A system for rapidly and accurately positioning a carriage as set forth in claim 1 wherein said arithmetic means comprises a subtraction register.
Claim 8
Dependent Claim
56 words
A system for rapidly and accurately positioning a carriage as set forth in claim 1 wherein said velocity decoder means comprises an electronic switch coupled to a plurality of transistor circuits each having a dropping resistor in series with a power supply to provide a plurality of voltage levels to the input of said amplifier means.
Claim 9
Independent Claim
222 words
A system for gross and fine positioning a magnetic head supported on a carriage opposite to the exact center of a track on a memory device, comprising means for rapidly positioning a magnetic head to the boundry edge defining a pre-selected track of a memory device, said means including a closed loop servo having a power source connected to a drive motor which is actuated by digital decoding means producing a voltage output proportional to the distance the magnetic head must travel to reach the boundry edge defining said pre-selected track said means further including an address register connected to said digital decoding means, displacement transducer means connected to said carriage and providing first and second signals indicative of the position of said magnetic head, said first signal providing a track count pulse to the digital decoding means, and switch means actuated by said address register for disconnecting said digital decoding means from said closed loop servo and connecting fine positioning means in said servo loop, said fine positioning means being responsive to said second signal which provides an analog voltage slope characteristic having a null or zero voltage output to said drive motor when said magnetic head is at the exact center of said track and having voltage outputs of opposite polarity at opposite sides of the center of said track.
Claim 10
Independent Claim
222 words
A system for gross and fine positioning a magnetic head supported on a carriage opposite to the exact center of a track on a memory device, comprising means for rapidly positioning a magnetic head to the boundry edge defining a pre-selected track of a memory device, said means including a closed loop servo having a power source connected to a drive motor which is actuated by digital decoding means producing a voltage output proportional to the distance the magnetic head must travel to reach the boundry edge defining said pre-selected track said means further including an address register connected to said digital decoding means, displacement transducer means connected to said carriage and providing first and second signals indicative of the position of said magnetic head, said first signal providing a track count pulse to the digital decoding means, and switch means actuated by said address register for disconnecting said digital decoding means from said closed loop servo and connecting fine positioning means in said servo loop, said fine positioning means being responsive to said second signal which provides an analog voltage slope characteristic having a null or zero voltage output to said drive motor when said magnetic head is at the exact center of said track and having voltage outputs of opposite polarity at opposite sides of the center of said track.
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) | 1976-03-19 | 1976-09-18 | 1977-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-19 | 1980-09-18 | 1981-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-19 | 1984-09-18 | 1985-03-20 | $7700.00 | Window Closed / Lapsed |