US3928772A - Time dependent fault detector - Google Patents

Time dependent fault detector Download PDF

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Publication number
US3928772A
US3928772A US45095974A US3928772A US 3928772 A US3928772 A US 3928772A US 45095974 A US45095974 A US 45095974A US 3928772 A US3928772 A US 3928772A
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US
United States
Prior art keywords
timer
time
capacitor
routines
alloted
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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English (en)
Inventor
Thomas J Mooney
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xerox Corp
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Xerox Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xerox Corp filed Critical Xerox Corp
Priority to US45095974 priority Critical patent/US3928772A/en
Priority to CA220,414A priority patent/CA1028002A/fr
Priority to GB1053575A priority patent/GB1495761A/en
Priority to BE154334A priority patent/BE826690A/fr
Application granted granted Critical
Publication of US3928772A publication Critical patent/US3928772A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/55—Self-diagnostics; Malfunction or lifetime display

Definitions

  • the detector n a I I I I I v I e e u e I [58] new of Search f:i 1; of a xerographic copier if any one of a plurality of opcrating sequences of the copier is not completed on a [56] References Cited tlmely basls' UNITED STATES PATENTS 4 Claims, 3 Drawing Figures 3,734,604 5/1973 Szostak et al 355/14 SCAN JAM JAM Sheet 1 of 2 U.S. Patent Dec. 23, 1975 Sheet 2 of2 3,928,772
  • This invention relates to failure detectors and, more particularly, to time dependent failure detectors.
  • time dependent failure detection is a relatively straightforward technique for monitoring any routine which normally advances from one identifiable point to another within a predetermined amount of time.
  • a timer having a time out period selected to equal the maximum time period required by a particular routine under normal operating conditions, means for triggering the timer into operation when the routine reaches the first or reference point, and means for resetting the timer when the routine reaches the other or termination point.
  • one of the important objects of the present invention is to provide a time dependent fault detector which may be utilized to monitor a plurality of mutually exclusive routines, even if those routines are alloted different amounts of time.
  • Another object of this invention is to provide a method and means for automatically adjusting the time out period of a time dependent fault detector to match the maximum amount of time alloted to any one of a plurality of mutually exclusive routines.
  • a further object of this invention is to provide a time dependent fault detector for automatically interrupting the operation of a xerographic copier if any one of a plurality of mutually exclusive operating sequences is not completed on a timely basis.
  • Still another object of the present invention is to provide a reliable and economical time dependent fault detector having the above-mentioned characteristics and capabilities.
  • means are provided in accordance with this invention for automatically adjusting the time out period of a timer in a time dependent fault detector.
  • Mutually exclusive routines to which different maximum time periods are alloted can, therefore, be monitored by a single detector since the time out period of the timer may be adjusted to match any one of them.
  • Adjustment of the time out period is conveniently accomplished by switching a transistor into and out of conduction to thereby vary the RC time constant of the timer.
  • FIG. 1 is a perspective view of a xerographic copier with which the present invention may be advantageously utilized;
  • FIG. 2 is a simplified schematic of the processor section of the copier shown in FIG. 1;
  • FIG. 3 is a schematic of a time dependent fault detector constructed in accordance with the present invention.
  • FIGS. 1 and 2 there is a xerographic copier 10 having a charging station 11, an exposure station 12, a development station 13, a transfer station 14 and a cleaning station 15 disposed about the periphery of a drum 16 which is coated with a photoreceptor 17.
  • a charging station 11 an exposure station 12
  • a development station 13 a transfer station 14
  • a cleaning station 15 disposed about the periphery of a drum 16 which is coated with a photoreceptor 17.
  • an original document is placed image side down on a transparent platen 18, a dial 19 is set to the desired number of copies, and a print button 21 is depressed to initiate the copying process.
  • Copying starts with the energization of a corona generator 22 at the charging station 11 to uniformly charge the photoreceptor 17.
  • the original document is flood illuminated by a suitable lamp (not shown) and is then scanned by a moving optics system 23 so that light reflected from the document is focused on the photoreceptor 17 at the exposure station 12.
  • the reflected light discharges the photoreceptor 17 in an imagewise configuration to thereby provide a latent electrostatic image.
  • the latent image is developed at the development station 13 by the application of an electroscopic toner powder, and the developed image is then transferred at the transfer station 14 to a copy sheet 24 which is fed from a cassette-type supply tray 25.
  • the toner image is permanently affixed to the copy sheet 24 at a fuser station 26 and residual toner is removed from the photoreceptor 17 at the cleaning station 15.
  • the time dependent fault detector 31 which is capable of monitoring mutually exclusive routines, even if they are alloted different amounts of time.
  • the capabilities of the detector 31 have been synergistically extended in accordance with this invention by including a timer 32 having an automatically adjustable time out period.
  • the timer 32 comprises a three terminal thyristor 33 which is switched from one state of conduction to the other when a timing capacitor 34 charges to a predetermined voltage level.
  • the charging time con stant for the capacitor 34 is adjusted under the control of a transistor 35 to thereby match the time out period of the timer 32 to the particular routine being monitored, and the timer 32 is triggered into operation and reset under the control of an inverter 36.
  • current is drawn from a dc. power supply through a resistor 37 and the parallel combination of collectoremitter circuit of the transistor 35 and another resistor 38.
  • the output of the inverter 36 is connected in parallel with the series combination of the timing capacitor 34 and a further resistor 39 in the ground return path for that current flow.
  • the current drawn from the dc. power supply is returned to ground through the timing capacitor 34 and it series resistor 39 or through the output of the inverter 36 depending on the logic level of the input signal applied to the input of the inverter 36. Specifically, if that signal is at a high (1) logic level, the timer 32 is triggered into operation because the current is routed through the timing capacitor 34 to charge it toward the critical voltage level. If, on the other hand, a low logic level signal is applied to the inverter 36, its output provides a relatively low impedance shunt path to ground for the current drawn from the dc. power supply and for any discharge current drawn by the capacitor 34.
  • the timer 32 when the timer 32 is triggered into operation, its time out period depends on the state of conduction of the transistor 35. If that transistor is in a nonconductive state, the RC charging time constant for the timing capacitor 34 is relatively long and the time out period of the timer 32 is, therefore, relatively long. But, if the transistor 35 is in a conductive state, the resistor 37 is effectively bypassed and, consequently, the charging time constant for the capacitor 34 is reduced to thereby reduce the time out period of the timer 32.
  • the thyristor 33 is a programmable unijunction transistor (PUT). As shown, the PUT 33 has its anode-cathode circuit coupled across the timing capacitor 34 and the resistor 39 and its gate coupled to a junction between a pair of voltage dividing resistors 41 and 42 which, in turn, are connected across the dc. supply source. As a result, there is a gate-cathode bias voltage which holds the PUT 33 in a non-conductive state until the timer 32 times out.
  • PUT programmable unijunction transistor
  • the PUT 33 switches into conduction because there then is sufficient voltage across the timing capacitor 34 to cause the anode-cathode voltage on the PUT 33 to exceed its gate-cathode bias voltage. In other words, time out of the timer 32 is marked by a significant drop in the gate-cathode voltage of the PUT 33.
  • the input and output interfaces 43 and 44, respectively, for the detector 31 are more or less tailored to its particular application to the copier 10 (FIGS. 1 and 2). That is, they are selected, together with the values of the capacitor 34 and of the resistors 37-39 and 41-42, to interrupt the operation of the copier 10 if the microswitch 28 (l) is not actuated within six seconds or so after the print button 21 is depressed or (2) remains actuated for more than about six tenths of a second at any time during a copying cycle.
  • the input interface relies on certain signals that are supplied by the copier 10 viz., (a) an initializing signal (INIT) which drops from a high l) logic level to a low (0) logic level approximately 20 milliseconds after the print button 21 is depressed, (b) a scan signal (SCAN) which is at a high (1) or a low (0) logic level depending on whether the microswitch 28 is actuated or not, and (c) a run signal (INIT BJAMF) which is herein assumed to simply be the complement of the initializing signal (INIT).
  • an initializing signal IIT
  • SCAN scan signal
  • IIT BJAMF run signal
  • the present invention provides a time dependent fault detector suitable for monitoring a plurality of mutually exclusive routines, even if different amounts of time are alloted to those routines.
  • 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 6 circuit; and further including means for applying a bias voltage to said gatecathode circuit, whereby said programmahle unijunction transistor switches from a nonconductive state to a conductive state when said timer times out.
  • 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.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Control Or Security For Electrophotography (AREA)
  • Accessory Devices And Overall Control Thereof (AREA)
US45095974 1974-03-14 1974-03-14 Time dependent fault detector Expired - Lifetime US3928772A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US45095974 US3928772A (en) 1974-03-14 1974-03-14 Time dependent fault detector
CA220,414A CA1028002A (fr) 1974-03-14 1975-02-19 Detecteur de panne temporelle
GB1053575A GB1495761A (en) 1974-03-14 1975-03-13 Xerographic copier with time dependent fault detector
BE154334A BE826690A (fr) 1974-03-14 1975-03-14 Detecteur de defectuosite dependant du temps

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US45095974 US3928772A (en) 1974-03-14 1974-03-14 Time dependent fault detector

Publications (1)

Publication Number Publication Date
US3928772A true US3928772A (en) 1975-12-23

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Application Number Title Priority Date Filing Date
US45095974 Expired - Lifetime US3928772A (en) 1974-03-14 1974-03-14 Time dependent fault detector

Country Status (4)

Country Link
US (1) US3928772A (fr)
BE (1) BE826690A (fr)
CA (1) CA1028002A (fr)
GB (1) GB1495761A (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4125326A (en) * 1977-03-11 1978-11-14 Pako Corporation Paper feed cut off for photographic printer
DE3133619A1 (de) * 1980-08-25 1982-06-24 Canon K.K., Tokyo Bilderzeugungseinrichtung
US4490035A (en) * 1981-08-20 1984-12-25 Minolta Camera Kabushiki Kaisha Abnormality detecting device for the original carriage of a copying machine
USD286887S (en) 1982-07-22 1986-11-25 Ricoh Company, Ltd. Electrostatic copier
US20080095196A1 (en) * 2006-10-20 2008-04-24 Rockwell Automation Technologies, Inc. Unit to unit transfer synchronization
US20080098401A1 (en) * 2006-10-20 2008-04-24 Rockwell Automation Technologies, Inc. Module arbitration and ownership enhancements
US20080097623A1 (en) * 2006-10-20 2008-04-24 Rockwell Automation Technologies, Inc. Standard mes interface for discrete manufacturing
US20080097628A1 (en) * 2006-10-20 2008-04-24 Rockwell Automation Technologies, Inc. Automatic fault tuning
US20080098351A1 (en) * 2006-10-20 2008-04-24 Rockwell Automation Technologies, Inc. Module class subsets for industrial control

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3734604A (en) * 1970-09-22 1973-05-22 Agfa Gevaert Ag Failsafe system for electrostatic copying apparatus

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3734604A (en) * 1970-09-22 1973-05-22 Agfa Gevaert Ag Failsafe system for electrostatic copying apparatus

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4125326A (en) * 1977-03-11 1978-11-14 Pako Corporation Paper feed cut off for photographic printer
DE3133619A1 (de) * 1980-08-25 1982-06-24 Canon K.K., Tokyo Bilderzeugungseinrichtung
US4490035A (en) * 1981-08-20 1984-12-25 Minolta Camera Kabushiki Kaisha Abnormality detecting device for the original carriage of a copying machine
USD286887S (en) 1982-07-22 1986-11-25 Ricoh Company, Ltd. Electrostatic copier
US20080095196A1 (en) * 2006-10-20 2008-04-24 Rockwell Automation Technologies, Inc. Unit to unit transfer synchronization
US20080098401A1 (en) * 2006-10-20 2008-04-24 Rockwell Automation Technologies, Inc. Module arbitration and ownership enhancements
US20080097623A1 (en) * 2006-10-20 2008-04-24 Rockwell Automation Technologies, Inc. Standard mes interface for discrete manufacturing
US20080097628A1 (en) * 2006-10-20 2008-04-24 Rockwell Automation Technologies, Inc. Automatic fault tuning
US20080098351A1 (en) * 2006-10-20 2008-04-24 Rockwell Automation Technologies, Inc. Module class subsets for industrial control
US7844349B2 (en) 2006-10-20 2010-11-30 Rockwell Automation Technologies, Inc. Standard MES interface for discrete manufacturing
US7894917B2 (en) * 2006-10-20 2011-02-22 Rockwell Automation Technologies, Inc. Automatic fault tuning
US8392008B2 (en) 2006-10-20 2013-03-05 Rockwell Automation Technologies, Inc. Module arbitration and ownership enhancements
US8601435B2 (en) 2006-10-20 2013-12-03 Rockwell Automation Technologies, Inc. Module class subsets for industrial control

Also Published As

Publication number Publication date
BE826690A (fr) 1975-06-30
GB1495761A (en) 1977-12-21
CA1028002A (fr) 1978-03-14

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