US3783235A - Fuser low voltage sensor for photocopy machine - Google Patents

Fuser low voltage sensor for photocopy machine Download PDF

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Publication number
US3783235A
US3783235A US00302588A US3783235DA US3783235A US 3783235 A US3783235 A US 3783235A US 00302588 A US00302588 A US 00302588A US 3783235D A US3783235D A US 3783235DA US 3783235 A US3783235 A US 3783235A
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US
United States
Prior art keywords
line voltage
fuser
photoconductor
voltage
monitoring
Prior art date
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
Application number
US00302588A
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English (en)
Inventor
R Sprague
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.)
Unisys Corp
Original Assignee
Sperry Rand Corp
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Filing date
Publication date
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current 
    • G05F1/12—Regulating voltage or current  wherein the variable actually regulated by the final control device is AC
    • G05F1/40—Regulating voltage or current  wherein the variable actually regulated by the final control device is AC using discharge tubes or semiconductor devices as final control devices
    • G05F1/44—Regulating voltage or current  wherein the variable actually regulated by the final control device is AC using discharge tubes or semiconductor devices as final control devices semiconductor devices only
    • G05F1/45—Regulating voltage or current  wherein the variable actually regulated by the final control device is AC using discharge tubes or semiconductor devices as final control devices semiconductor devices only being controlled rectifiers in series with the load
    • G05F1/455—Regulating voltage or current  wherein the variable actually regulated by the final control device is AC using discharge tubes or semiconductor devices as final control devices semiconductor devices only being controlled rectifiers in series with the load with phase control
    • 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
    • G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
    • G03G15/2003—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat
    • G03G15/2007—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using radiant heat, e.g. infrared lamps, microwave heaters
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current 
    • G05F1/12—Regulating voltage or current  wherein the variable actually regulated by the final control device is AC
    • G05F1/40—Regulating voltage or current  wherein the variable actually regulated by the final control device is AC using discharge tubes or semiconductor devices as final control devices
    • G05F1/44—Regulating voltage or current  wherein the variable actually regulated by the final control device is AC using discharge tubes or semiconductor devices as final control devices semiconductor devices only
    • G05F1/445—Regulating voltage or current  wherein the variable actually regulated by the final control device is AC using discharge tubes or semiconductor devices as final control devices semiconductor devices only being transistors in series with the load

Definitions

  • ABSTRACT A fuser system for a xerographic photocopy machine.
  • the fuser system comprises primary and secondary fuser heating resistors connected in parallel legs across an AC. line voltage.
  • the primary fuser heating resistor is connected directly across the line voltage and continuously produces fusing heat.
  • a triac is connected in series with the secondary fuser resistor and a monitoring-and-controlling circuit is connected in parallel with the first and second parallel legs, across the line voltage, for monitoring the line voltage and controlling the triac so as to cause electrical current flow through the secondary fuser heating resistor when the line voltage drops below a predetermined value.
  • the monitoring-and-controlling circuit comprises a lamp and a photoconductor, each being connected in parallel across the line voltage. Light from the lamp controls the voltage across the photoconductor and the voltage across the photoconductor is used to control current flow through the triac.
  • This invention relates broadly to the art of photocopying machines and more specifically to photocopy ing machines which employ fuser heating units for fusing developer powder to copy sheets.
  • fuser heating units of xerographic-type photocopying machines produce heating temperatures which fall within fixed ranges. In this regard, if the heating temperatures are unduly high they may damage copy sheets which are processed by the fuser heating units. On the other hand, if temperatures are excessively low they do not produce the proper fusing of developer powder to the copy sheets.
  • a problem which is sometimes encountered in the use of photocopying machines is that A.C. line voltages decrease, thereby causing heating resistors of fuser heating units to radiate decreasing amounts of heat, which, in turn, produces decreasing fusing temperatures.
  • a line voltage which is normally 120 volts
  • drops below 105 volts a fuser heating unit produces insufficient heat to effect proper fusing.
  • FIG. 1 there is shown a simplified side elevation of a xerographic photocopying machine comprising a photoconductive drum 11, a developerpowder unit 13, a cleaning brush 15, an optical system 17, an image transfer unit 19, and a fuser heating unit 21.
  • the manner in which the xerographic photocopying machine of FIG. 1 produces developer-powder images on copy sheets 23 is well known in the art and therefore not explained here.
  • the copy sheets 23, having developer-powder images thereon, are transported under the fuser heating unit 21 which applies heat for fusing the developer powder to the copy sheets 23.
  • the fuser heating unit 21 has a primary heating element 25 and a secondary heating element 27.
  • FIG. 2 the schematic electrical diagram of FIG. 2, it can be seen that the primary heating element 25 and the secondary heating element 27 are connected in parallel legs across an A.C. line voltage 29. Connected in series with the secondary heating element 27 is an electronic valve 31 in the form of a triac.
  • the electronic valve 31 is controlled by the voltage appearing at a valve-control voltage point 33.
  • the voltage appearing at the valvecontrol point 33 is established by a voltage divider and control circuit 35 which comprises a fixed resistor 37, and a photoconductor 39 and capacitor 41 connected in parallel.
  • the conductanceof the photoconductor 39 is increased by increasing the light radiating upon the photoconductor.
  • a lamp 43 is also connected across the A.C. line voltage 29.
  • the lamp senses or monitors the line voltage and produces lumination proportional to the magnitude of the line voltage.
  • a potentiometer 45 is connected in series with the lamp 43 for adjusting the sensitivity of the lamp 43.- It can be seen in FIG. 2 that the lamp 43 and the photoconductor 39 are positioned relative to each other such that light from the lamp 43 falls on the photoconductor 39 and thereby causes an increase in conductance of the photoconductor 39.
  • the primary heating element 25 conducts a normal current and thereby dissipates a planned amount of energy in the form of heat; thus, the fuser heating unit 21 provides a desired amount of heat for fusing developer powder to copy sheets 23.
  • the lamp 43 produces a suffi' cient amount of light to make the conductance of the photoconductor 39 relatively high so that the peaks of the voltage control signal at the valve-control voltage point 33 are at relatively low amplitude.
  • the electronic valve (triac) 31 is not fired during A.C. cycles in either direction and, therefore, no current flows through the secondary heating element27.
  • the lamp 43 provides less light on the photoconductor 39 and the resistance of the photoconductor increases. This causes the peak amplitudes of the voltage control signal at the valve control voltage point 33 to increase.
  • the voltage at control voltage point 33 fires the electronic valve (triac) 31 and current flows through the secondary heating element 27, element 27 therefore dissipates energy which is added to the energy dissipated by the primary heating element 25 to increase the amount of heat produced by the fuser heating unit 21.
  • the triac is turned on so that element 27 may generate additional heat.
  • the control of triac 31 is essentially binary or ON-OFF in character. Over a l or 2 volt variation in the A.C. line voltage, in the region of about 108 volts, the triac 31 may, as is well known, be fired for only a portion of the cycle. However, the components of the monitoring and controlling circuit are chosen such that the range of line voltages over which this type of operation takes place is limited. Thus, in a typical embodiment there may be no current flow through element 27 when the line voltage is above about 108 volts, but there will be current flow through the element 27 throughout each cycle when the line voltage is below 107 volts.
  • a fuser heating system for a photocopying machine comprising:
  • primary and secondary fuser heating elements connected respectively in first and second parallel legs across said line voltage leads;
  • a monitoring-and-controlling circuit connected in parallel with said first and second parallel legs across said line voltage leads for monitoring said line voltage and controlling said electronic valve so as to cause an increase in electrical current flow through said valve in response to a decrease in line voltage.
  • a fuser heating system as claimed in claim 1 wherein said monitoring-and-controlling circuit comprises a lamp which is connected across said line voltage leads, and a photoconductor, the conductance of which varies in response to light emitted by said lamp, connected across said line voltage leads.
  • monitoring-and-controlling circuit further comprises a resistor in series with said photoconductor, a capacitor in parallel with said photoconductor, and means for applying a voltage developed at the junction point between said photoconductor, said resistor, and said capacitor, to said triac as a control voltage.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Fixing For Electrophotography (AREA)
  • Control Of Resistance Heating (AREA)
  • Resistance Heating (AREA)
  • Control Or Security For Electrophotography (AREA)
  • Control Of Temperature (AREA)
US00302588A 1972-10-31 1972-10-31 Fuser low voltage sensor for photocopy machine Expired - Lifetime US3783235A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US30258872A 1972-10-31 1972-10-31

Publications (1)

Publication Number Publication Date
US3783235A true US3783235A (en) 1974-01-01

Family

ID=23168397

Family Applications (1)

Application Number Title Priority Date Filing Date
US00302588A Expired - Lifetime US3783235A (en) 1972-10-31 1972-10-31 Fuser low voltage sensor for photocopy machine

Country Status (9)

Country Link
US (1) US3783235A (enExample)
JP (1) JPS4978561A (enExample)
BR (1) BR7305132D0 (enExample)
CA (1) CA996991A (enExample)
DE (1) DE2335718C3 (enExample)
FR (1) FR2204822B1 (enExample)
GB (1) GB1376553A (enExample)
IT (1) IT995340B (enExample)
NL (1) NL7314489A (enExample)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3881085A (en) * 1972-12-06 1975-04-29 Xerox Corp Fuser control circuit for copying apparatus
US4161644A (en) * 1976-09-24 1979-07-17 Ricoh Co., Ltd. Electrophotographic apparatus comprising improved thermal fixing means
US4180721A (en) * 1976-09-22 1979-12-25 Ricoh Company, Ltd. Method of controlling fixing temperature of powder image in electrophotographic copying machine

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3040158A (en) * 1960-12-01 1962-06-19 Hewlett Packard Co Proportional temperature controller
US3419708A (en) * 1966-04-06 1968-12-31 Whirlpool Co Electronic heat control for dryer
US3532855A (en) * 1968-12-30 1970-10-06 Ibm Power regulating circuit for xerographic fusing apparatus

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1329941A (fr) * 1962-07-27 1963-06-14 Générateur régulé pour basse tension
FR1439059A (fr) * 1965-02-04 1966-05-20 Centre Nat Rech Scient Perfectionnements aux dispositifs pour contrôler les circuits électriques à haute tension
GB1187569A (en) * 1966-04-28 1970-04-08 Arlside Ltd Reprographic Apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3040158A (en) * 1960-12-01 1962-06-19 Hewlett Packard Co Proportional temperature controller
US3419708A (en) * 1966-04-06 1968-12-31 Whirlpool Co Electronic heat control for dryer
US3532855A (en) * 1968-12-30 1970-10-06 Ibm Power regulating circuit for xerographic fusing apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3881085A (en) * 1972-12-06 1975-04-29 Xerox Corp Fuser control circuit for copying apparatus
US4180721A (en) * 1976-09-22 1979-12-25 Ricoh Company, Ltd. Method of controlling fixing temperature of powder image in electrophotographic copying machine
US4161644A (en) * 1976-09-24 1979-07-17 Ricoh Co., Ltd. Electrophotographic apparatus comprising improved thermal fixing means

Also Published As

Publication number Publication date
NL7314489A (enExample) 1974-05-02
IT995340B (it) 1975-11-10
JPS4978561A (enExample) 1974-07-29
DE2335718C3 (de) 1979-08-23
DE2335718B2 (de) 1975-04-30
BR7305132D0 (pt) 1974-07-25
FR2204822B1 (enExample) 1977-02-11
GB1376553A (en) 1974-12-04
DE2335718A1 (de) 1974-05-09
CA996991A (en) 1976-09-14
FR2204822A1 (enExample) 1974-05-24

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