US4721895A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multi-speed analog servo
Assignee: Qume Corp
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Filing: 1983-11-22
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Granted: 1988-01-26
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Expires: 2003-11-22
Abstract
Abstract An analog servo system suitable for accurately controlling the carriage speed of a high speed printer over a relatively wide range. The system includes an analog tachometer with circuit means which enables the tachometer to operate in either a high gain mode (used at normal or lower carriage speeds) or a low gain mode (used at higher carriage speeds). The tachometer gain mode (or "electronic gear") is controlled by an external command signal such as a single bit supplied by the control microprocessor of the printer. The state of the command signal controls a time constant in the tachometer circuit means which determines the gain mode.
Inventors
- 👤 Kenneth W. Cocksedge
- 👤 William N. Thanos
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:44
CPC Classifications
H; H02; H02P; H02P23/00; H02P23/16
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
109 words
In an analog tachometer circuit for generating a tachometer signal in response to a sinusoidally varying encoder signal whose frequency is proportional to the speed being measured and which includes analog differentiating means responsive to said encoder signal and a predetermined time constant to generate a differential signal whose magnitude is representative of said speed, the improvement comprising: first means for establishing a first time constant corresponding to a first speed range; second means for establishing a second time constant corresponding to a second speed range; and switching means responsive to an external command for selectively providing said first or said second time constant to said analog differentiating means.
Claim 2
Dependent Claim
109 words
In an analog tachometer circuit for generating a tachometer signal in response to a sinusoidally varying encoder signal whose frequency is proportional to the speed being measured and which includes analog differentiating means responsive to said encoder signal and a predetermined time constant to generate a differential signal whose magnitude is representative of said speed, the improvement comprising: first means for establishing a first time constant corresponding to a first speed range; second means for establishing a second time constant corresponding to a second speed range; and switching means responsive to an external command for selectively providing said first or said second time constant to said analog differentiating means.
Claim 3
Dependent Claim
119 words
The servo of claim 1 further comprising a digital-to-analog converting means responsive to a plurality of digital velocity bits to produce a resultant analog reference output and analog comparing means for comparing said reference output with said tachometer signal to produce a servo error output, wherein said improvement further comprises means for coordinating a change in said differential signal in response to said external command being applied to said switching means with the change in said analog reference output in response to a change in said plurality of velocity bits whereby said servo error output signal will be essentially unaffected when said tachometer is switched from one of said speed ranges to a different one of said speed ranges.
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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) | 1991-01-25 | 1991-07-27 | 1992-01-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-25 | 1995-07-27 | 1996-01-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-25 | 1999-07-27 | 2000-01-26 | $7700.00 | Window Closed / Lapsed |