US3807854A - Drive mechanism for photsensitive web in an image transfer type electrophotographic copier - Google Patents

Drive mechanism for photsensitive web in an image transfer type electrophotographic copier Download PDF

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Publication number
US3807854A
US3807854A US00326360A US32636073A US3807854A US 3807854 A US3807854 A US 3807854A US 00326360 A US00326360 A US 00326360A US 32636073 A US32636073 A US 32636073A US 3807854 A US3807854 A US 3807854A
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United States
Prior art keywords
photosensitive element
suction
roller
suction box
electrophotographic copier
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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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US00326360A
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English (en)
Inventor
T Fujiwara
S Tanaka
Y Enoguchi
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Minolta Co Ltd
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Minolta Co Ltd
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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
    • G03G15/75—Details relating to xerographic drum, band or plate, e.g. replacing, testing
    • G03G15/754—Details relating to xerographic drum, band or plate, e.g. replacing, testing relating to band, e.g. tensioning
    • 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
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G03G15/28—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which projection is obtained by line scanning
    • G03G15/283—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which projection is obtained by line scanning using a reusable recording medium in form of a band

Definitions

  • ABSTRACT An apparatus comprising a photosensitive element made of a flexible sheet to be moved reciprocally for each image transfer cycle, a suction box fixedly supporting one end of the photosensitive element at its inlet portion and subjected to a reduced pressure in its interior by pressure reducing means to draw in the photosensitive element along its inner wall and to thereby tension the element to a planar form at an exposure station, and drive means for defining the path of advance of the photosensitive element and defining the direction of movement of the same.
  • the present invention relates to electrophotographic copiers of the image transfer type, more particularly to an apparatus for driving a photosensitive element to be used repeatedly in electrophotographic copiers of the image transfer type such as the electrostatic latent image transfer type, powder image transfer type and the like.
  • the photosensitive element used in electrophotographic copiers of the image transfer type has a photoconductive film which is electrostatically charged by a charger and then exposed to reflected light from the surface of document to form the image of the document as an electrostatic latent image.
  • Suchphotoconductive film is generally adhered to a drum or belt for repeated use.
  • the photosensitive element gets deteriorated due to repeated use over a long period, the photosensitive element has to be replaced along with the drum or belt. The replacing procedure is therefore very cumbersome and expensive.
  • a drum of a large diameter for providing the photosensitive element on its surface has in its interior a supply roll and a takeup roll, and the photosensitive element wound on the.supply roll is paid out over the drum surface, with the leader end of the element wound on the takeup roll.
  • the photosensitive portion on the drum surface has been deteriorated, the deteriorated portion is wound up on the takeup roll to pull out a fresh photosensitive portion.
  • the photosensitive element extending around the drum surface is subjected all the time to mechanical tension exerted by the takeup roll.
  • the photosensitive elementof this apparatus is driven by the rotation of the drum to pass through a corona unit, exposure station, developing unit and transfer station which are disposed around the drum for the transfer copying operation already known.
  • a roll of flexible photosensitive element is paid out from a supply roll and the leader end is wound on a takeup roll, the photosensitive element extending between the two rolls in a taut planar fashion. If the extending portion gets deteriorated, the deteriorated portion is wound up on the takeup roll to pull out a fresh portion from the supply roll for use.
  • the photosensitiveelement is always subjected to mechanical tension, with the two rolls kept spaced apart by a constant distance, and the rolls and the photosensitive elements in this state are moved reciprocally in a horizontal direction.
  • Various means for transfer copying operation are disposed in series along the path of the reciprocation to conduct the copying operation already known.
  • the two examples described have the drawback that the photosensitive element is susceptible to fatigue due to stress, hence a short service life and marked wear of the element inasmuch as the flexible photosensitive element is subjected to mechanical tension all the time. Moreover, since the photosensitive element is driven on the support drum or is reciprocated over a distance several times the space between the rolls while being supported on the rolls, the construction requires a large space for driving the photosensitive element, making the copier greater in size to occupy an increased floor space.
  • An object of this invention is to subject a flexible photosensitive element to a minimum of requisite tension when it is driven reciprocally for a transfer copying operation so as to keep the element planar at the exposure station and to thereby prevent the shortening'of its service life and cost increase due to its wear.
  • Another object of this invention is to simplify the construction of a mechanism for driving the photosensitive element to the greatest possible extent and to reduce the space volume required for driving the photosensitive element so as to provide a compact electrophotographic copier of the type described.
  • Still another object of this invention is to provide an apparatus of a very simple construction capable of returning the photosensitive element quickly for reciprocation.
  • the apparatus of this invention is characterized by suction means for moving the photosensitive element along its inner wall by drawing the same in one direction so as to subject the element to tension and means for defining the direction of movement of the photosensitive element.
  • the suction to be exerted on the photosensitive element to keep the same planar at the exposure station is given by suction means which produces a very low negative pressure of the order of 30 mm Aq'. and it has become possible to greatly reduce the tension on'the photosensitive element as compared with the known apparatus, this consequently making it possible to materially reduce the stress to be produced in the photosensitive sensitive element by the tension.
  • the invention simplifies the mechanism for driving the photosensitive element and reduces the space volume required for the reciprocation of the element.
  • FIG. 1 is a view partly in vertical section showing the principal part of an embodiment of this invention
  • FIGS. 2(a) and (b) are views illustrating the operation of a photosensitive element in the embodiment of FIG. 1;
  • FIG. 3 is a view partly in vertical section showing the principal part of another embodiment of this invention.
  • FIG. 4 is a view partly in vertical section showing the principal part of another embodiment of this invention.
  • FIGS. (a) and (b) are views illustrating the operation of a photosensitive element in the embodiments of FIGS. 3 and 4.
  • FIG. 1 shows an electrophotographic copier of the electrostatic latent image transfer type.
  • a document table 1 made of a transparent material such as a glass plate is fixedly positioned at the top of a frame A.
  • a document B to be copied is placed face down on the table 1 and is illuminated by a lamp L of an illuminating system 2.
  • the illuminating system 2 has a first movable system comprising the lamp L and a reflecting mirror M 21 second movable system comprising reflecting mirrors M and M a stationary system comprising an imageforming lens 3 and a reflecting mirror M and an exposure slit 4 for projecting the reflected light from the surface of the document to an exposure station E.
  • first movable system comprising the lamp L and a reflecting mirror M 21
  • second movable system comprising reflecting mirrors M and M
  • a stationary system comprising an imageforming lens 3 and a reflecting mirror M and an exposure slit 4 for projecting the reflected light from the surface of the document to an exposure station E.
  • the first movable system travels at a velocity of v while the second movable system travels at a velocity of v/2 so that the reflected light from the surface of the document illuminated by the lamp L is projected, by means of the first and second movable systems and the reflecting mirror and lens of the stationary system, onto a flexible photosensitive element P moving at the same velocity v in synchronism with the first movable system so as to form an electrostatic latent image on the photosensitive element P.
  • a suction box 5 has at its one end an inlet portion 5a where a stock roller 6, serving to fix one end of the photosensitive element P, is removably mounted.
  • the suction box 5 has at the'other end thereof an exhaust fan 7 or like suction means, with cloth 5b such as silicone cloth adhered to the inner surface of the box.
  • the flexible photosensitive element P has one end se cured to the stock roller 6 and the other end secured to a take-up roller 8 which is always urged by an unillustrated spiral coiled spring or the like toward a direction to wind up the photosensitive element P.
  • a guide roller 9 positioned between the stock roller 6 and the take-up roller 8 defines the path of movement of the photosensitive'element.
  • a drive roller 10 is out of contact with the'photosensitive face of the element P but is in elastic contact with the widthwise opposite edges of the element P or with the opposite ends of the guide roller 9 and rotates the roller 9 to drive the photosensitive element P at the same velocity as the first movable system in synchronism with the exposure making operation of the illuminating system 2.
  • the drive roller 10 rotates in the normal direction to advance the photosensitive element P in synchronism with the first movable system and rotates in the reverse direction upon completion of a transfer operation to move the element P backward.
  • unillustrated electromagnetic means or suitable mechanical means may separate the drive roller 10 from the photosensitive element P or from the guide roller 9 as shown in FIG. 2(b) to permit the photosensitive element P to be returned by the suction of the suction box 5.
  • the stock roller 6 is formed with a cavity for accommodating the unused portion (with fresh photosensitive face) of the element and the takeup roller 8 is formed with a cavity for housing the used portion (with deteriorated photosensitive face) of the photosensitive element.
  • the rollers are provided with slits for paying out and for drawing in the photosensitive element respectively, the slits having means for securing the opposite ends of the operative portion of the photosensitive element respectively.
  • the operative portion i.e. the portion in use
  • the deteriorated portion is wound up into the take-up roller 8, with a fresh photosensitive portion paid out from the stock roller 6.
  • Such winding and unwinding operations can be conducted by any desired means automatically or manually.
  • a roll of copy paper 15 is cut to a predetermined copy size by a cutter 16 and pressed by the belt 12 against the surface of the photosensitive element P for the transfer of the electrostatic latent image.
  • the copy paper bearing the electrostatic latent image thereon is separated from the photosensitive element P by a separator 17, led to developing means 18 for development, passed under a heater 19 by a fixing belt 19a and sent out from the frame through a copy outlet 20.
  • the photosensitive element is driven in the following manner.
  • the exhaust fan 7 is driven to exhaust the air from the suction box 5, with the result that the photosensitive element P is drawn into the box along its inner wall as shown in FIG. 1 (by solid line) and FIG. 2(a) and thereby subjected to predetermined tension.
  • the document B is placed on the table 1 and an unillustrated start switch is depressed, whereupon the lamp L is lighted and the first and second movable systems of the illuminating system 2 are initiated into travel from the solid line position in FIG. 1 toward the broken line position while maintaining the aforesaid relationship therebetween.
  • the photosensitive element P is driven in synchronism with the first movable system against the suction of the box 5.
  • the charging, exposure and transfer of the image are conducted and the element P is wound up on the takeup roller 8.
  • the image transfer operation will be completed upon the first and second movable system and the photosensitive element P reaching the broken line position of FIG. 1.
  • the photosensitive element P has reached the broken line position of FIG. 1 (i.e. the position shown in FIG. 2(b)
  • the drive roller 10 is driven in the reverse direction to return the photosensitive element P or, as shown in FIG. 2(b), the
  • the biasing force of the spiral coiled spring acting on the take-up roller 8 is of course set at a lower level than the suction of the I box 5. Further during the return movement of the photosensitive element P, the transfer belt 12 is of course released from the photosensitive surface.
  • the first and second movable systems of the illuminating system 2 are returned to the solid line position of FIG. 1 simultaneously with the completion of the image transfer operation or upon completion of exposure.
  • the movable systems and the photosensitive element are stopped when they have travelled a distance corresponding to the smaller copy size before reaching the broken line position of FIG. 1 and are then returned to the respective solid line positions.
  • the silicone cloth5b provided on the inner wall of the suction box 5 serves to automatically clean the photosensitive surface of the element P by sliding contact therewith during the movement of the element P, eliminating the need to incorporate a special cleaner in the copier to simplify the construction.
  • the cloth further serves to protect the photosensitive surface from scratching.
  • the suction box prevents the lateral deflection of the photosensitive element with its side wall during the reciprocal movement of the element so as to enable the element to advance straight.
  • the suction box 5 further serves to guide the photosensitive element with its upper wall and eliminates the vertical shake or the photosensitive element along with the guide roller 9.
  • the assembly .of the rollers including the roll of photosensitive element P accommodated in the stock roller 6 may be constructed in the form of a cassette, this making it possible to replace the photosensitive element P very easily and quickly. Since the tension acting on the photosensitive element during the copying operation is very small, the element is almost free of fatique and deterioration due to the tension. Thus one photosensitive surface is able to conduct several tens of thousands of copying cycles.
  • the roll of photosensitive element loaded in the stock roller is so adapted that a fresh photosensitive portion can be paid out when the preceeding portion gets fatigued, one roll of photosensitive element will be able to perform hundreds of thousands of copying cycles, with troubles reduced for the replacement of the photosensitive element.
  • FIG. 3 shows an electrophotographic copier of the electrostatic image transfer type as described in which a suction box 30 has two reduced pressure chambers 31 and 32.
  • a stock roller 6 is positioned at an inlet portion 31a of the first reduced pressure chamber 31 and a take-up roller 8a is disposed at an inlet portion 32a of the second reduced pressure chamber 32.
  • the rollers are removably but fixedly mounted in place.
  • the take-up'roller 8a need not be provided with a spiral coiled spring or the like for winding up the operative photosensitive portion during the advance of the element as in the embodiment of FIG. 1.
  • the take-up roller 8a remains stationary against rotation.
  • the same parts as those shown in FIG. 1 are referred to by the same reference numerals.
  • the suction box 30 is divided by a partition wall 30a into upper and lower sections, i.e. into the first reduced pressure chamber 31 and second reduced pressure chamber 32, and both chambers 31 and 32 are given suction by a common exhaust fan 7 through passages 31b and 32b.
  • Cleaning cloth 320 such as silicone cloth is adhered to a portion to be in sliding contact with the photosensitive surface of the element P.
  • the stock roller 6 and the take-up roller 8a are disposed at the inlet portions 31a and 32a of the first and second reduced pressure chambers 31 and 32 respectively.
  • the photosensitive element P held at its opposite ends to the rollers 6 and 8a has a portion thereof to be exposed passed around guide rollers 9 and 21 and is driven forward by a drive roller 10. Between the guide rollers 9 and 21, the photosensitive element P is in contact with a transfer belt 12.
  • FIG. 4 shows the suction box 30 of FIG. 3 as it is incorporated in a frame A of an electrophotographic copier of the powder image transfer type to apply this invention to the copier.
  • the parts similar I to those shown in FIG. 3 are referred to by the same reference numerals.
  • a transfer charger 22 Disposed along the path of movement of the photosensitive element P are a transfer charger 22 in place of the transfer belt of FIG. 3 and a developing and cleaning box 23 in place of the developing means.
  • the developing and cleaning box 3 is supported on the frame A in upwardly and downwardly movable manner.
  • developing means 24 is rotated at the illustrated position near the path of movement of the photosensitive element P to supply toner from a toner feeder 25 to the photosensitive element P to form an electrostatic latent image on the photosensitive surface into a visual powder image.
  • the visual image is then transferred by the transfer charger 22 to copy paper.
  • the copy paper with the transferred image thereon is carried by a belt 26a to fixing means 26 for fixing and then sent out from the frame through the copy outlet 20.
  • the developing and cleaning box 23 is moved upward as indicated by the arrow to bring a cleaner 27 to the path of movement of the photosensitive element P, and the cleaner 27 is driven to clean the photosensitive surface.
  • the dust is drawn into a dust box 29 by a dust fan 28.
  • the photosensitive element P in the embodiments of FIGS. 3 and 4 is driven as illustrated in FIGS. 5(a) and (b).
  • the first chamber 31 and the second chamber 32 are given interior reduced pressure by the common exhaust fan 7 to draw in the photosensitive element P along their inner walls.
  • the passage 31b between the first chamber 31 and the exhaust fan 7 is larger than the passage 32b between the second chamber 32 and the exhaust fan 7 to give a greater suction to the first chamber 31 than to the second chamber 32.
  • the photosensitive element P When the exhaust fan 7 is initiated into operation by depressing the main switch, the photosensitive element P is drawn into the first reduced pressure chamber 31 as illustrated in FIG. (a) and is subjected to tension in contact with the inner wall face thereof under the suction of the first and second chambers 31 and 32.
  • the depression of the start switch causes the drive roller to rotate the guide roller 9, forcing the photosensitive element P to start from the position of FIG. 5(a) against the suction of the first chamber 31, followed by exposure and image transfer as previously described.
  • the element P reaches the position of FIG. 5(b) (if the copy size is maximum). More specifically, the photosensitive element P is drawn into the second chamber 32 along its inner wall. At this time, the photosensitive surface is cleaned by the cleaning cloth 32c.
  • the drive roller 10 Upon completion of the transfer operation, the drive roller 10 is driven reversely or is released from the guide roller 9 as shown in the drawing, whereupon the photosensitive element P is returned quickly from the position of FIG. 5(b) to the position of FIG. 5(c) inasmuch as the first chamber 31 has greater suction than the second chamber 32.
  • the passages 31b and 32b may alternatively be provided with a changeover valve or throttle valve to give greater suction to the second chamber 32 than to the first chamber 31 during the advance of the photosensitive element P and further to give greater suction to the first chamber 31 than to the second chamber 32 during the backward movement of the element P.
  • the drive roller 10 may then act simply to control the velocity of movement of the photosensi tive element P.
  • An electrophotographic copier of the image transfer type comprising:
  • a photosensitive element made of a flexible sheet to be used repeatedly by being driven reciprocally for each image transfer cycle
  • a suction box having means for securing one end of the photosensitive element to its inlet portion and subjected to a reduced pressure in its interior by pressure reducing means, the suction box being operable to exert suction on the photosensitive element to draw in the element along the inner wall of the box upon actuation of the pressure reducing means and to thereby tension the element to a planar form at an exposure station,
  • exposure means for forming an image of an original on the charged face of the photosensitive element in the exposure station forward of the charging means to form a latent electrostatic image of the original on the photosensitive element face
  • the electrophotographic copier as set forth in claim 1 wherein the means for fixedly supporting the other end of the photosensitive element comprises a take-up roller so biased all the time as to wind up the photosensitive element in a direction opposite to the direction of suction of the suction box.
  • the means for fixedly supporting the other end of the photosensitive element comprises a second suction box having means for securing the other end of the photosensitive element to its inlet portion and subjected to a reduced pressure in its interior by pressure reducing means for exerting suction on the photosensitive element in a direction opposite to the direction of suction of the first-mentioned suction box, the second suction box being operable to draw in the photosensitive element along the inner wall of the box during the advance of the element.
  • the drive means for the photosensitive element comprises a guide roller for passing the photosensitive element thereon to define the path of advance of the same and a drive roller for defining the movement of the photosensitive element in cooperation with the roller.
  • the photosensitive element is a roll of flexible sheet having an unused roll portion accommodated in a stock roller mounted at the inlet portion of the suction box, another portion in use one end of which is fixedly supported on the stock roller and a used roll portion wound up on a take-up roller, the other end of the portion in use being fixedly supported on the take-up roller.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Discharging, Photosensitive Material Shape In Electrophotography (AREA)
US00326360A 1972-02-07 1973-01-24 Drive mechanism for photsensitive web in an image transfer type electrophotographic copier Expired - Lifetime US3807854A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP47013699A JPS4883836A (US07576130-20090818-C00114.png) 1972-02-07 1972-02-07

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US3807854A true US3807854A (en) 1974-04-30

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US00326360A Expired - Lifetime US3807854A (en) 1972-02-07 1973-01-24 Drive mechanism for photsensitive web in an image transfer type electrophotographic copier

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US (1) US3807854A (US07576130-20090818-C00114.png)
JP (1) JPS4883836A (US07576130-20090818-C00114.png)
DE (1) DE2305684A1 (US07576130-20090818-C00114.png)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4218026A (en) * 1978-06-23 1980-08-19 Xerox Corporation Paper web buffer system
US4355882A (en) * 1981-02-26 1982-10-26 Xerox Corporation Multiple function reproduction apparatus
US4367942A (en) * 1980-03-26 1983-01-11 Fuji Photo Film Co., Ltd. Xerographic copying machine
US4396274A (en) * 1979-12-03 1983-08-02 International Business Machines Corporation Electrophotographic copier configuration
EP0124375A2 (en) * 1983-04-28 1984-11-07 Xerox Corporation Electrostatographic apparatus
US4970551A (en) * 1988-09-16 1990-11-13 International Business Machines Corporation Cartridge containing a reciprocating photoconductor ribbon for serial electrophotographic printing

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4511237A (en) * 1982-04-08 1985-04-16 Konishiroku Photo Industry Co., Ltd. Electrophotographic reproducing machine
JPS59192280A (ja) * 1983-04-15 1984-10-31 Ricoh Co Ltd 複写装置
EP0333157B1 (en) * 1988-03-16 1993-12-08 Sharp Kabushiki Kaisha Method of controlling transport of photoreceptive sheet

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3646866A (en) * 1967-10-16 1972-03-07 Addressograph Multigraph Photoelectrostatic copier having a single station for simultaneously applying toner particles and cleaning the photoconductive medium
US3650622A (en) * 1970-03-09 1972-03-21 Eastman Kodak Co Apparatus for control of bias potential in an electrophotographic copier
US3697160A (en) * 1969-04-30 1972-10-10 Xerox Corp Continuous imaging apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3646866A (en) * 1967-10-16 1972-03-07 Addressograph Multigraph Photoelectrostatic copier having a single station for simultaneously applying toner particles and cleaning the photoconductive medium
US3697160A (en) * 1969-04-30 1972-10-10 Xerox Corp Continuous imaging apparatus
US3650622A (en) * 1970-03-09 1972-03-21 Eastman Kodak Co Apparatus for control of bias potential in an electrophotographic copier

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4218026A (en) * 1978-06-23 1980-08-19 Xerox Corporation Paper web buffer system
US4396274A (en) * 1979-12-03 1983-08-02 International Business Machines Corporation Electrophotographic copier configuration
US4367942A (en) * 1980-03-26 1983-01-11 Fuji Photo Film Co., Ltd. Xerographic copying machine
US4355882A (en) * 1981-02-26 1982-10-26 Xerox Corporation Multiple function reproduction apparatus
EP0124375A2 (en) * 1983-04-28 1984-11-07 Xerox Corporation Electrostatographic apparatus
US4490033A (en) * 1983-04-28 1984-12-25 Xerox Corporation Reproducing apparatus with scrolled imaging web
EP0124375A3 (en) * 1983-04-28 1985-11-21 Xerox Corporation Electrostatographic apparatus
US4970551A (en) * 1988-09-16 1990-11-13 International Business Machines Corporation Cartridge containing a reciprocating photoconductor ribbon for serial electrophotographic printing

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JPS4883836A (US07576130-20090818-C00114.png) 1973-11-08
DE2305684A1 (de) 1973-08-16

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