US3826569A - Exposure safeguarding device for photocopying machine - Google Patents

Exposure safeguarding device for photocopying machine Download PDF

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Publication number
US3826569A
US3826569A US00336377A US33637773A US3826569A US 3826569 A US3826569 A US 3826569A US 00336377 A US00336377 A US 00336377A US 33637773 A US33637773 A US 33637773A US 3826569 A US3826569 A US 3826569A
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United States
Prior art keywords
exposure
sensing element
temperature sensing
time
temperature
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Expired - Lifetime
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US00336377A
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English (en)
Inventor
H Sakamaki
Y Kimura
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Canon Inc
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Canon Inc
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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
    • G03G15/04—Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material
    • G03G15/04036—Details of illuminating systems, e.g. lamps, reflectors
    • 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
    • G03G15/04—Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material
    • G03G15/043—Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material with means for controlling illumination or exposure

Definitions

  • the present invention relates generally to a safety device for an electrophotographic copying machine and more particularly an exposure safeguarding device for preventing under-exposure which would result in a poor'quality copy.
  • the photocopying machines of the type generally used in offices and the like are required to be compact in size, easy and simple in maintenance and free from noise and heat so, that the environmental conditions may not be adversely affected. Therefore, the above method which requires heating and cooling means has a defect that the photocopying machine becomes inevitably large in size and complex in construction.
  • the above method may be used in'a large-sized photocopying machine, but when it is applied to a small-sized photocopying machine for office use the cost and the dimensions are increased, the maintenance becomes complex, and the office environment is adversely affected because heat is generated.
  • an effective method for compact photocopying machines for office use for overcoming the problem caused by the variation in rising time of a light source reaching a predetermined threshold level.
  • One of the objects of the present invention is there fore to provide an exposure safeguarding device for an electrophotographic copying machine of the type using fluorescent-lamps as a light source for exposure,'which is simple in construction and may prevent underexposure which would result in poor quality copies.
  • Another object of thepresent invention is to provide an exposure safeguarding device for an electrophotographic copying mahcine which permits the photocopying operation to start at the optimum time depending upon the environmental temperature.
  • Another object of the present invention is to provide an exposure safeguarding device best adapted to be incorporated in a compact photocopying machine.
  • the present invention provides an exposure safeguarding device for a photocopying machine of the type using an exposure light source such asfluorescent lamps in which the time delay obtained by a time-delay circuit for delaying the start of the driving system of the photocopying machine is varied in response to the detected environmental temperature so that when the brightness of a light source reaches the optimum level the photocopying operation may be started.
  • FIG. 1 is a graph used for the explanation of variations in rise time of the brightness of a light source of a photocopying machine depending upon the environmental temperature;
  • FIG. 2 is a sectional view of a small-sized electrophotocopying machine to which is applied an exposure safeguarding device in accordance with the present invention
  • FIGS. 3 and 4 are diagrams of an electric circuit of the electrophotographic copying machine shown in FIG. 1 including an electric circuit of the exposure safeguarding device;
  • FIG. 5 is an electric circuit diagram of another em- 'bodiment of the'present invention adapted for continuously controlling the delay time.
  • FIG. 2 illustrating a compact-sized electrophotographic copying machine
  • an original which is transported over a glass plate 2 in an illumination stage 1 is illuminated by lamps 3 so that the image of the original may be focused upon a sensitive drum 7 through an exposure stage 6 consisting of a reflecting mirror 4 and a mirror lens 5.
  • the photosensitive member upon the surface of the drum 7 comprises a photosensitive layer coated with a transparent insulating layer.
  • the sensitive drum 7 which is rotated in the direction indicated by the arrow is charged positively by a first charger 9 electrically connected to a high-voltage source 8.
  • an AC discharging operation is performed by means of a discharger 10 to which is applied high AC voltage from the power source 8. Then, the drum is subjected to whole-surface-exposure by means of a lamp 11, whereby an electrostatic latent image may be formed upon thesurface of thesensitivedrum 7.
  • An electrostatic latent image may be also formed by the first DC charging, the simultaneous projection of the 3 original image with a second charging of opposite polarity, and the whole-surface-exposure or'application of the second charging is applied justafter projection of the original image.
  • the latent image is developed by a developing agent 13 in a developer 12, and then applied with corona discharge by the high negative voltage applied to a post charger 14 so that the excess developing agent may be removed without the developed image being adversely affected.
  • a copysheet P which is fed from a copy sheet I stand or the like by a feed roller 15 is brought into contact with the sensitive drum 7 so that the developed image thereupon may be transferred to the copy sheet P when positive corona discharge is applied by a charger IGQThereaft er the copy sheet P is separated from the sensitive drum 7 by a separating belt 17, and is transported into a fixing stage 19 by means of an endless belt conveyer 18.
  • the copy sheet P in the fixing stage -19 is heated by a heater 20 and by the heated air discharged from a duct 21 through a discharge port 21 around the heater 20 so that the copy sheet P is fixed and dried. Thereafter the charge'remaining on the copy sheet P is removed by a discharger 22, 'andthe copy sheet is deposited upona tray 26 through a discharge opening 24 and a shoot 25 by a discharge roller 23.
  • FIGS 3 and 4 are the diagrams of an electric circuit of the photocopying machine-shown in FIG. 2 including a safeguarding device in accordance with the present invention.
  • Door switches 27 and 28 connected to AC lines are closed when a doorof the housing of the photocopying sult the transistorQ6 may conduct, but its conduction is also controlled by the thyristor 02 so that only when the latter conducts. after the time delay, the transistor Q6 conducts and a relay K2 is energized.
  • the main motor M1, the high-voltage sources 8(AC) and 8(DC) and the lamp 11 for the whole-surface illumination are then energized so that the photocopying operation can commence.
  • FIG. 5 is a circuit diagram of another embodiment of a temperature detector in which is used a temperaturesensitive element such as thermistor Th whose resistance R(t) is substantially linearly varied in response to temperature variations so that the time required for charging a capacitor C2 in a time-delay circuit may be varied.
  • the time delay To(T) is dependent upon the resistance R(T) of the thermistor, and the resistances of a variable resistor VR3 and a fixed resistor R1, and the capacitance Cl as in the case'of the first embodiment described above.
  • thermoswitch SM2 is set to. 15 C.
  • thermoswitch SM2 is opened, and the setting time T1 is dependent upon the values of and the capacitor and resistances VRl VR2 R connected in series therewith.
  • the thermoswitch SM2 is closed so that the resistor VRl is short-circuited. Therefore, the setting time T2 is dependent upon the resistance VR2 R1 and the capacitance Cl.
  • an N-gate thyristor Q1 is cut off and a diode D1 is sufficiently biased so that as soon as the switch SW is closed the capacitor C3 is immediately charged through a resistor R7, the diode D1 and a resistor R9. Since the time constant (R7 R9) C3 is sufficiently smaller than that of the delay circuit, transistors Q3 and 04 connected through a resistor R11 to the capacitor C3 are made to conduct so that a relay K1 is energized and the illumination or exposure lamps 3 which are operatively coupled to the relay K1 are turned on.
  • a transistor 05 when the relay K1 is energized a transistor 05 is cut off so that the base of a transistor O6 is forward biased through the device RLl and resistors R15, R16, and R17.
  • a rephotocopying operation may be started only after the brightness of the fluorescent lamps has risen above a predetermined level. Therefore, an image-of desired quality may be obtained from a first copy by utilizing and the exposure safeguarding devicei'n accordance with the present invention, which device is simple in construction.
  • an electrophotographic copying machine of the type comprising an original holder, an exposure light source, a sensitive member upon which is reproduced the image of an original placed upon said original holder, an optical system for focusing said original upon said sensitive member, processing means disposed around said sensitive means for producing a copy of said original, means for driving said 'machine to effect copy processing, and means for controlling energization of said driving means, an improvement comprising an exposure safeguarding device having a tempera-. ture.
  • time-delay means coupledto said temperature sensing element and having an output for producing a signal after a delay time t which commences with actuation of said exposure light source, and which changes in response to temperature variationssensed by said temperature sensing element, and means coupled between said time-delay means output and said driving means for controlling the energization of said driving means.
  • thermosensor comprises switch means adapted to turn on or off at a predetermined threshold temperature.
  • time-delay means comprises a time constant circuit consisting of resistor means and capacitor means and said temperature sensing element is connected in parallel with one of said resistor means.
  • said temperature sensing element comprises switch means adapted to turn on or off at a predetermined threshold temperature
  • said time-delay means comprises a time constant circuit including capacitor means and a plurality of resistor means and has said temperature sensing element connected in parallel with one of said resistor means

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Control Or Security For Electrophotography (AREA)
  • Light Sources And Details Of Projection-Printing Devices (AREA)
  • Exposure Or Original Feeding In Electrophotography (AREA)
  • Control Of Exposure In Printing And Copying (AREA)
US00336377A 1972-03-03 1973-02-27 Exposure safeguarding device for photocopying machine Expired - Lifetime US3826569A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2214072A JPS5724529B2 (enrdf_load_stackoverflow) 1972-03-03 1972-03-03

Publications (1)

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US3826569A true US3826569A (en) 1974-07-30

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Application Number Title Priority Date Filing Date
US00336377A Expired - Lifetime US3826569A (en) 1972-03-03 1973-02-27 Exposure safeguarding device for photocopying machine

Country Status (3)

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US (1) US3826569A (enrdf_load_stackoverflow)
JP (1) JPS5724529B2 (enrdf_load_stackoverflow)
DE (1) DE2310394C3 (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3976374A (en) * 1974-04-18 1976-08-24 Rank Xerox Ltd. Elimination of redundant image
US4095890A (en) * 1975-06-24 1978-06-20 Oce-Van Der Grinten N.V. Xerographic copying apparatus
US4133420A (en) * 1977-07-15 1979-01-09 Copylite, Inc. Coin operated coin device for a copy machine
US4202623A (en) * 1979-01-08 1980-05-13 The Perkin-Elmer Corporation Temperature compensated alignment system
US4297616A (en) * 1980-03-17 1981-10-27 Xerox Corporation Fluorescent lamp with incandescent ballasting systems
US4463284A (en) * 1981-07-28 1984-07-31 Konishiroku Photo Industry Co., Ltd. Method and apparatus for controlling luminous intensity of fluorescent lamp of reproducing apparatus
US4536681A (en) * 1983-07-19 1985-08-20 Minnesota Mining And Manufacturing Company Temperature compensated time exposure control circuit
US4827306A (en) * 1984-10-17 1989-05-02 Sharp Kabushiki Kaisha Discharging apparatus and method for use in a copying machine
US20020024595A1 (en) * 1999-12-23 2002-02-28 Spence Stuart T. Optical design for film conversion device
US6724420B2 (en) * 1999-12-23 2004-04-20 Dfr2000, Inc. Portable film conversion device

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5456711A (en) * 1977-10-14 1979-05-08 Nippon Telegr & Teleph Corp <Ntt> Photoelectric converter
JPS5740276A (en) * 1980-08-23 1982-03-05 Ricoh Co Ltd Exposure stabilizing device
JPS60177216A (ja) * 1984-02-22 1985-09-11 Seiritsu Kogyo Kk 機械的変位を電気信号に変換する装置
JPS60230017A (ja) * 1984-04-27 1985-11-15 Tokyo Keiki Co Ltd 光電型変位量検出装置
JPH07111540B2 (ja) * 1986-05-12 1995-11-29 カシオ計算機株式会社 画像形成装置

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3330180A (en) * 1964-10-14 1967-07-11 Xerox Corp Illumination control system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3330180A (en) * 1964-10-14 1967-07-11 Xerox Corp Illumination control system

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3976374A (en) * 1974-04-18 1976-08-24 Rank Xerox Ltd. Elimination of redundant image
US4095890A (en) * 1975-06-24 1978-06-20 Oce-Van Der Grinten N.V. Xerographic copying apparatus
US4133420A (en) * 1977-07-15 1979-01-09 Copylite, Inc. Coin operated coin device for a copy machine
US4202623A (en) * 1979-01-08 1980-05-13 The Perkin-Elmer Corporation Temperature compensated alignment system
US4297616A (en) * 1980-03-17 1981-10-27 Xerox Corporation Fluorescent lamp with incandescent ballasting systems
US4463284A (en) * 1981-07-28 1984-07-31 Konishiroku Photo Industry Co., Ltd. Method and apparatus for controlling luminous intensity of fluorescent lamp of reproducing apparatus
US4536681A (en) * 1983-07-19 1985-08-20 Minnesota Mining And Manufacturing Company Temperature compensated time exposure control circuit
US4827306A (en) * 1984-10-17 1989-05-02 Sharp Kabushiki Kaisha Discharging apparatus and method for use in a copying machine
US20020024595A1 (en) * 1999-12-23 2002-02-28 Spence Stuart T. Optical design for film conversion device
US6611293B2 (en) 1999-12-23 2003-08-26 Dfr2000, Inc. Method and apparatus for synchronization of ancillary information in film conversion
US20040071445A1 (en) * 1999-12-23 2004-04-15 Tarnoff Harry L. Method and apparatus for synchronization of ancillary information in film conversion
US6724420B2 (en) * 1999-12-23 2004-04-20 Dfr2000, Inc. Portable film conversion device
US6829012B2 (en) * 1999-12-23 2004-12-07 Dfr2000, Inc. Method and apparatus for a digital parallel processor for film conversion
US6864913B2 (en) 1999-12-23 2005-03-08 Harry L. Tarnoff Method and apparatus for a reconfigurable digital processor for film conversion
US6891562B2 (en) 1999-12-23 2005-05-10 Stuart T. Spence Optical design for film conversion device

Also Published As

Publication number Publication date
JPS4890536A (enrdf_load_stackoverflow) 1973-11-26
DE2310394A1 (de) 1973-09-13
DE2310394C3 (de) 1975-11-13
JPS5724529B2 (enrdf_load_stackoverflow) 1982-05-25
DE2310394B2 (de) 1975-04-03

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