US3928772A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Time dependent fault detector
Assignee: Xerox Corp
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Filing: 1974-03-14
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Granted: 1975-12-23
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Expires: 1994-03-14
Abstract
Abstract The RC time constant of a timer in a time dependent fault detector is automatically varied so that the timer may be used to monitor a plurality of mutually exclusive routines to which different maximum permissible periods of time are alloted. For example, the detector may be advantageously used to interrupt the operation of a xerographic copier if any one of a plurality of operating sequences of the copier is not completed on a timely basis.
Inventors
- 👤 Thomas J Mooney
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:01
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/55
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
142 words
In combination with a xerographic copier having a plurality of mutually exclusive routines each alloted a different amount of time, a time dependent fault detector for interrupting the operation of said copier whenever any one of said routines fails to be completed within the time alloted thereto; said detector comprising a timing capacitor, a resistive path for supplying charging current for said capacitor, a shunt path coupled in parallel with said capacitor for bypassing said charging current around said capacitor until one of said routines is initiated, means responsive to the initiation of any one of said routines for disabling said shunt path to thereby trigger said timer into operation, and means for selectively bypassing a portion of the resistance in said path to thereby adjust the time out period of said timer to match the time alloted to said one routine.
Claim 2
Dependent Claim
142 words
In combination with a xerographic copier having a plurality of mutually exclusive routines each alloted a different amount of time, a time dependent fault detector for interrupting the operation of said copier whenever any one of said routines fails to be completed within the time alloted thereto; said detector comprising a timing capacitor, a resistive path for supplying charging current for said capacitor, a shunt path coupled in parallel with said capacitor for bypassing said charging current around said capacitor until one of said routines is initiated, means responsive to the initiation of any one of said routines for disabling said shunt path to thereby trigger said timer into operation, and means for selectively bypassing a portion of the resistance in said path to thereby adjust the time out period of said timer to match the time alloted to said one routine.
Claim 3
Dependent Claim
35 words
The combination of claim 1 wherein said timer further includes a thyristor which switches from one state to another when said capacitor charges to a predetermined voltage level, thereby marking time out of said timer.
Claim 4
Dependent Claim
62 words
The combination of claim 2 wherein said thyristor is a programmable unijunction transistor having an anodecathode circuit and a gate-cathode circuit, and said capacitor is coupled across said anode-cathode circuit; and further including means for applying a bias voltage to said gatecathode circuit, whereby said programmable unijunction transistor switches from a non-conductive state to a conductive state when said timer times out.
Claim 5
Dependent Claim
41 words
The combination of claim 3 wherein said bypass means includes a transistor having a collector-emitter circuit connected in parallel with said resistance, whereby the time out period of said timer is adjusted by switching said transistor into and out of conduction.
References Cited (Backward Citations)
US3734604A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-22 | 1979-06-23 | 1979-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-22 | 1983-06-23 | 1983-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-22 | 1987-06-23 | 1987-12-23 | $7700.00 | Window Closed / Lapsed |