FR2498778A1 - PHOTOCOPIER EQUIPPED WITH A SHEET DETACHER APPARATUS AND PROCESS FOR REMOVING A SHEET FROM THE PHOTOSENSIBLE SURFACE OF SAID PHOTOCOPIER - Google Patents

Abstract

THE INVENTION CONCERNS PHOTOCOPIERS. IT RELATES TO A SHEET DETACHING MECHANISM IN WHICH A DETACHING BODY HAVING A TIP 86 CONSTANTLY IN CONTACT WITH THE PHOTOSENSITIVE SURFACE 15 SPREADS A CORNER OF A PRINT SHEET 40 WHICH IS IMMEDIATELY ENTERED BETWEEN ROLLS 64 AND 74 THE IMAGE IT WEARS CANNOT BE DIRTY BY THE DETACHING ORGAN. THIS IS MOVING CROSS-CALLS IN A PROGRESSIVE AND ALTERNATIVE MANNER. APPLICATION TO LIQUID DEVELOPER PHOTOCOPIERS.

Description

The present invention relates generally

  photocopiers and in particular a process and a

  intended to detach the leaves from a photo-surface

  sensitive fragile, after transfer of a developed image of this surface to a sheet of print.

  A photocopier implements a photo-surface

  sensitive mobile that is electrically charged and then exposed

  to an image formed by an energy, most often a

  sin formed by light energy obtained by scanning

  an original document. Energy is focused on the over-

  charged side so that it forms an electrostatic image

  the tent. The latter is developed, then the image develops.

  lopped is carried on a sheet of material

  carried out in close contact with the surface area

which brings the developed image.

  The leaf is then detached from the photo-

  sensitively and then transported away from the surface along an exit path. A fix or fusion station is

  usually arranged along its exit path.

  The drawing sheet, when put in contact

  of the photosensitive surface, usually adheres to

  in a narrow way given the electrostatic fields

  created during photocopying and copying operations.

  port and, in addition, in the case of copying machines

  liquid, because of the surface tension due to the

  liquid. The sheet must be detached from the surface with minimal disturbance of the developed image which is generally fragile, and with minimal or no deterioration of the fragile photosensitive surface. In at least one commercially available dry copier, a short draft is projected between the sheet

  the photosensitive surface so that the

  interior of this sheet is separated and can be

  tight or may fall away from the photosen-

  sible. The print sheet is then transported to the fuser or fuser station. This air-blasting method has the disadvantage of being able to disturb the particles of coloring matter which adhere to the printing sheet and to be very sensitive to the different parameters controlling

  the operation of the entire apparatus.

  There are also many different devices in which a mechanical organ comes in contact material

  with the fragile photosensitive surface. A process, particularly

  particularly useful in the case of photocopiers with developer

  described in more detail in the US Pat.

  United States of America No. 4,000,942, implements a set of

  detachment with a long blade in contact with a mar-

  ginal of the photosensitive surface. As the drawing sheet advances this surface, a marginal edge of the sheet slides along the detaching blade. This directs a front portion of the front edge of the sheet in cooperation with the roll grip. A disadvantage of this method is that the entire marginal edge of the sheet can not be in contact with the photosensitive surface and is therefore unavailable for reproduction. The pressure of the blade on the photosensitive surface can also cause wear

  or a deterioration of the surface placed below.

  In another method generally used only in dry copying machines, an organ is either constantly in contact with the surface or placed in contact with it in a synchronized manner without loss of image on the printing sheet so that the risks of deterioration of the surface are reduced. In each case, the loose paper can generally "fall" on a conveyor system intended to drive it to an exit station where it is directed to rollers placed at a distance from the surface. This device has the disadvantage of being able to deteriorate the image and, when the movement is synchronized on the print sheet, to require a suitable synchronization and a precise position of the device so that it does not deteriorate

  the photosensitive surface or fragile image and that the

  sheet is performed reliably.

  The literature also discloses a sheet detaching apparatus in which the detachment mechanism is moved transversely to a limited portion of the drum so that it more surely avoids deterioration of the photosensitive surface of the drum. In such an apparatus (U.S. Patent No. 4,168,902), the sheet detachment member constantly moves alternately oscillating on a limited portion of the width of the surface of the

  photosensitive drum. The real element of leaf detachment

  is intended to move away from the surface of the drum by means of

  Votively when the sheet, which is a relatively rigid organ according to this patent, comes to strike it. In a second document, U.S. Patent No. 4,252,310,

  a sheet detachment mechanism is intended to

  place transversely to a limited part of the drum, in small steps. The steps are controlled by a ratchet assembly and a smooth cam surface.For example,

  the sheet detachment element operates in synchronism

  me with the arrival of the image transfer sheet so that the detachment element pivots down, in contact

  the surface of the drum just before the sheet arrives.

  ve and pivots away from the drum when the sheet has been detached from it. In both cases, the sheet can fall on what appears to be equivalent to a conveyor belt system intended to ensure the displacement

to the exit station.

  The device that uses a leaf detachment

  back-and-forth movement seems to be used with a revelation

  dry and be used for the removal of the detacher mechanism from the surface of the drum whenever this is

  necessary. It requires mechanisms and synchronization

  additional requirements that increase the complexity and cost of the sheet release mechanism. In addition, these known mechanisms with back and forth movement do not allow sufficient adjustment of the positioning of the element.

  leaf detachment on the surface of the photosensitive member.

  The invention essentially relates to minimizing the disruption of the photocopying process and reducing the potential formation of stains or soiling on the image of the printing sheet in producing a reliable sheet peeling apparatus

  and long lasting. The invention also relates to the

  the maximum available sheet area for the print run. It also relates to a sheet peeling apparatus which has a precise, stable, inexpensive, durable and simple construction, the installation of which is simple and requires virtually no maintenance. It also relates to a sheet detachment apparatus and method particularly suitable for liquid developer copiers. The invention relates to a method and an apparatus

  removal of a printing sheet from the photo-surface

  sensitive, in a photocopying machine. This device has

  a movable member having a photosensitive surface, elements

  means for forming a developed image on the photosensitive surface, and an apparatus for advancing a print material intended to contact the photosensitive surface at a station at which the transfer of the developed image is effected.

on the drawing material.

  The sheet removal assembly includes a sheet detachment member having a work portion resiliently urged against the photosensitive surface to contact an anterior edge of the copy sheet upon passage to the element. leaf detachers, and that it detaches this anterior edge of the leaf of the

  photosensitive surface. The set also comprises a first

  first movable deflection surface which has a superficial

  very close to the working part of the sheet detachment element and which is on the path of the detached front edge so that it deviates this detached edge

  away from the sheet detachment member and preferably

  to a second moving friction surface. The invention further implements driving elements of at least one of the first and second movable surfaces so that the copy sheet is directed to an exit path.

  that removes it from the photosensitive surface.

  The invention also relates to a method of removing a printing sheet from the photosensitive surface of a photocopier. The latter has elements intended to form a developed image on the photosensitive surface, elements intended to advance the drawing sheet so that it is in contact with the photosensitive surface at a transfer station to which the developed image is postponed. on the printing sheet, and removal elements of the transfer sheet of the photosensitive surface. This process includes

  resilient return of a leaf detachment member,

  that an active part of it is placed against

  the photosensitive surface and come into contact with an

  inside the print sheet when it moves

  to the leaf detachment element. The process

  further includes detaching the leading edge of the printing sheet from the photosensitive surface with the active portion of the detachment member, and disposing of a movable deflection surface near the active portion of the detent detachment member so that the detached front edge of the sheet is deviated substantially instantaneously and is kept away from the detachment member and directed to the exit path. The method further comprises driving the movable deflection surface so that it moves away

  the printing sheet of the photosensitive surface, preferably

  at a speed greater than the peripheral speed of the photosensitive surface. Thus, the sheet is diverted

  far from the photosensitive surface, far from the detachment

and to the exit route.

  The invention also relates to a sheet removal assembly having a detachment element, an active part of which is resiliently pushed against the photosensitive surface.

  so that it is in contact with an anterior edge of the

  when it moves towards the detachment element, and detaches the front edge of the sheet from the surface

  photosensitive. The set includes a set of training

  detachment element intended to move gradually

  the element in a direction substantially parallel to the

photosensitive surface.

  The invention also relates to the implementation, in

  this embodiment, a first circumferential surface

  having several separate but related positions during operation, intended to maintain a surface area

  positioning, at several positions chosen successively

  is lying. The invention also relates to an assembly intended to re-

  bind the detachment element to the positioning surface during operation so that it moves into the

  same as the detachment element, and a body of

  camming device for driving a second circumferential surface such that the detacher element moves

  towards a new position with respect to the photo-

  sensitive. The invention also relates to an apparatus for actuating the cam drive member when a limit

predetermined has been reached.

  In an advantageous embodiment, the invention relates to a drive assembly having a cam member and a plurality of separate position-holding surfaces, operatively connected, for positioning purposes.

  of a cam surface at several positions chosen succes-

  and an elastic member for biasing the detaching member in the direction of its movement against the cam surface. The drive assembly also includes a drive member connected to a second set of position holding surfaces and for moving the cam member.

  so that the detachment element moves to a new

  position relative to the photosensitive surface. Linen-

  The invention also relates to a mechanism for actuating the driving cam after a predetermined number of draws has been performed, so that the detaching element does not remain supported in an axial position of the surface.

  long enough to disturb the photosensitive surface

  during the expected useful life of the

area.

  Other features and advantages of the invention

  tion will become more apparent from the following description,

  made with reference to the accompanying drawings in which Figure 1 is a schematic elevation of a photocopier made according to the invention;

  FIG. 2 is an elevation of the surface area

  tosensitive and sheet detachment apparatus according to the invention, the drawing sheet being at the post office;

  FIG. 3 is an elevation showing the sur-

  photosensitive face and the sheet detachment apparatus according to

  invention, while the printing sheet was just

  the photosensitive surface by its anterior edge;

  FIG. 4 is an elevation showing the sur-

  photosensitive face and the sheet detachment apparatus according to the invention while the sheet is moving along the output path; Figure 5 is an enlargement of the circled portion of Figure 2;

  FIG. 6 is an elevation showing the sur-

  photosensitive face and the detaching apparatus according to a second embodiment of the invention while the printing sheet is at the transfer station;

  FIG. 7 is a diagrammatic elevation

  sensing the position of the sheet detachment member relative to the xerographic drum, in a particular embodiment of the invention;

  FIG. 8 is an elevation of the clipping mechanism

  progressive advance according to an advantageous embodiment

  tageux of the invention; Fig. 9 is a section showing the connection of the ratchet assembly and the side cam assembly

  according to an advantageous embodiment of the invention.

  tion; Fig. 10 is an almost completely sectional elevation showing the ratchet drive mechanism of Fig. 8; Figure 11 is a section of the support member

  and alternative movement of the sheet detacher assembly

the, elastically recalled; and

  FIG. 12 is a graph showing the range of

  the relative position of the stripper

  sheet, in ordinate, according to the position of the

seems to ratchet, rotating.

  The invention is described with reference to FIG. 1 applied to a liquid developer photocopier 12 having

  a rotary drum 14 which itself has a photosensitive surface

  15. The invention also applies to a device without

  bour, for example a copier whose photosensitive surface has the configuration of a belt. The drum shown has a photosensitive surface layer of selenium deposited on an aluminum substrate and is rotated in a counter-clockwise direction as indicated by the arrow 16, by a motor 17. A device 18 charging corona

  charges the photosensitive surface 15 of the drum at 1000 V

  about tinus. The charged surface is exposed to an image,

  at an exhibition post. In the embodiment

  presented, the image is transmitted to the drum by an arrangement

  lens 22 including a lens and mirrors,

  nance of a document 24 illuminated by lamps 26.

  The image is focused on the photosensitive surface of the drum and, on it, the surface charge progressively forms a latent electrostatic image. The latter, carried by the surface, is transmitted to a post

  30 of development to which a liquid developer 32, containing

  negatively charged particles of a co-

  lorante, comes into contact with the electrostatic image so that it is developed. The development station shown is provided with developer reservoir 34 and development electrode 36. The developer 32 is introduced between the electrode and the surface 15 so that the electrostatic image is developed. The surface 15 of

  drum which is then wet and which carries the image developing

  loppée moves in front of a metering roll 38 which adjusts and limits the thickness of liquid developer carried by the

drum surface.

  A print sheet 40 is transmitted to the

  surface 15, at a post 42 of report. Sheet 40 is trans-

  brought to the surface, in particular by means of rollers 44 for positioning in a marked position, in a well-known manner, and it is

  in contact with the surface of the drum, in the mode of

  shown, just before a device 46 of

  port by effluvium. A positive charge arising from the

  Figure 46 is applied to the back of the sheet 40 so that the dye particles of the developed image on the surface of the drum are carried on the sheet 40. This is detached from the surface of the drum by an assembly 48. according to the invention which directs the sheet 40 along an exit path to driven rollers 54.

  transport the sheet to a heating element

  for fixing the wet liquid image, then to

  a copy receiving tray (not shown).

  After postponement, an unwanted residue of liquid remains on the surface of the drum, and is removed by a

  roll 56 and a blade 58 which are in contact with the surface.

  After cleaning and before the next charge, the surface of the

  drum is electrically neutralized by a

  the alternative neutralization voltage applied by a

  device 59 for forming corona.

  As indicated in FIGS. 2 to 4, the illustrated depot 48 for picking up sheets according to the invention is progressively displaced transversely to the surface of the drum, parallel to this surface. Translation

  of the whole is achieved, in the mode of

  considered at the beginning of a reproduction cycle.

  The depicted assembly 48 of sampling has a square 60

  mounting plate formed by a flat plate and attached to a

  me 61 alternative workout or following a movement

  back and forth and on which is mounted an element de-

  Tacheur 62 which is elastically repulsed and can pivot, a first and a second roll roll 64 and 65 elastically pushed and connected by connecting rods 66 and 67 so that they move around the same pivot axis 68, and a third and a fourth neck roll 70 and 72 having fixed positions. The rolled rollers 64 and 65 are resiliently biased against a rubber-coated driven roller 74 and the rollers 70 and

  72 are placed at a distance from the roller 74.

  In the embodiment shown, the element 62 is a planar element mounted so that it can pivot in a plane substantially perpendicular to the axis of the rotary drum, that is to say aligned with the direction of displacement of the drum. photosensitive surface at their point of contact. Similarly, in the embodiment shown, the axes of rotation of the rollers are parallel to each other.

  to the others and the axis 68 of pivoting.

  In its normal operating position, the element

  detacher 62 cooperates elastically with the surfaze photosen-

  15 of the drum 14. The element 62 is pushed back elastically

  around the axis 80 of pivoting under the action of a spring 82. It is fixed at one end to the mounting bracket and is wound on a screw 63 shoulder and bears, at a second extremity, in a throat 84

  of the element 62. This detacher element 62 is thus repouss-

  se in the clockwise direction (in FIG. 2) about the axis so that an end 86 of the element 62 comes elastically

  in contact with the light-sensitive surface 15. The pressure exerted

  end 86 against the surface 15 is regulated by the

spring 82.

  In a preferred embodiment of the invention,

  vention, the pressing force of the tip 86 against the surface 15

  is in the order of 0.03 to 0.04 N. In other modes of

  and, depending on the device parameters during operation, a lower force can be used in practice. In the embodiment considered, the angle formed by the contact surface 86a of the tip 86, upstream or forward, with a tangent to the drum at the point of contact of the tip 86 and the surface of the drum, is understood

  between about 52 and 73 and in the embodiment

  felt, he is 62. The location of the pivot axis 80 with respect to the center of the drum does not have to be adjusted with great precision; in the embodiment considered, the whole of the axis corresponds to an inclination, beyond the upper part of the drum, of 21.780 and 14.98 above the tangent to the point of contact. Figure 7 shows in detail the blade-shaped element. The rollers 70 and 72 of the assembly 48 have a fixed position as indicated above, and are mounted accurately on the plate 60 so that they are spaced from the surface 87 of the roll 74. The illustrated roller 74

  has a coating 88 of rubber on a metal core 88a.

  The rolled rollers represented 64 and 65 are pushed back

  elastically, as indicated previously, so that they can

  move independently of the surface 87 of the roll 74. Each roll 64 and 65 is guided by a

  slot 89, 89a formed in the respective mounting part 60

  tively. An elastic restoring force is applied to the roller 64 by a spring 90 which is mounted between the bracket 60 and the connecting rod 66. The rotation of the connecting rod 66 causes translation of the roll 64 in the slot 89 about the axis 68. Similarly, the roller 65 is pushed back

  towards the surface 87 by a spring 93 which is fixed between the

  60 and the connecting rod 67. The rotation of the connecting rod 67 pro-

  the movement of the roller 65 in the slot 89a, about the axis 68. The rollers 64 and 65 are driven by the roller 74. All the rollers 64, 65, 70 and 72 are preferably rolls with normalized surface and knurling

  medium (no 21) and are commercially available.

  The roller 74 is driven at a sensible speed

  constant by connecting to the drum drive system. Preferably, this connection is set so that the surface 87 of the roll has a peripheral speed

  barely greater than that of the photosensitive surface 15.

  For example, the speed of the photosensitive surface 15 may

  being 12.5 m / min and that of surface 87 13.1 m / min.

  (If the peripheral speed of surface 87 is approximately equal to that of the photosensitive surface, it may appear

  a wrinkling that can cause a stain of the image).

  However, in a second embodiment of the invention

  described in the following, the peripheral speed

  surface 87 is selected so that it is clear

  higher than that of the surface 15 so that a pull sheet is removed from the detachment member 62 after

  the edge of the leaf was grasped by the right of way

  64 and 74, after the removal of the photosen-

  sible. In this latter embodiment, the roller 74 is driven for example by a clutch which can slide so that the sheet is not removed from the drum before the transfer of the image. Thus, the anterior edge of the sheet is driven at an initial speed substantially greater than that of the photosensitive surface and, after turning on, the speed of the leading edge of the sheet decreases.

  at a value substantially equal to that of the photo-surface

  sensitive. In addition, in this latter embodiment,

  adjusting the location of the roll 64 with respect to the

  socket 86 can be fixed with greater freedom.

  As indicated previously, during normal operation according to the invention, the tip 86 of the detachment element bears gently against the photosensitive surface 15

  of the drum under the action of the return spring 82. In con-

  Sequence, in this embodiment, the pressure exerted by the end 86 against the surface of the drum can be adjusted easily and independently. In addition, the detachment member 62 has a configuration such that the tip 86 bears against the photosensitive surface at its end (see FIG. 7) so that a sheet which adheres to the surface of the drum

  can be more easily detached. Element 62 represents

  is a plane organ of "Mylar" having a thickness of

  0.35 mm and being in a substantially perpendicular plane

  to the photosensitive surface. In other embodiments, the element 62 may be formed of any sufficiently rigid material (armed if necessary as in the embodiment shown) not deteriorating the surface of the drum. Examples of suitable materials are polypropylene, "Lexan", "nylon", "Teflon", etc.

  Thickness does not seem essential but it is advantageous

  as little as possible (while giving a

  long-term use) so that the risk of accumu-

  the coloring matter on the end of the blade is reduced, this accumulation may cause a marking

  of the sheet during the detachment operation.

  The detachment element 62 is advantageously positioned so that it is in contact with the surface 15 and that it raises above it an anterior edge of a drawing sheet, by a wedge, by deflection of the remote corner of the photosensitive surface and direction of this corner almost immediately to the roller 64 (see Figure 3). The size of the tip 86, i.e., the angle "a" shown in FIG. 7, is preferably about 55. As indicated previously, the position of the tip with respect to a tangent to the point of contact, that is to say

  the downstream angle "b" is preferably of the order of 1280.

  As shown in FIG. 7, the detachment member 62 in the form of a flat sheet is preferably

  ence placed between two thin metallic elements 200 support (only one is shown in the figure). The detachment member shown 62 (in this configuration) has its

  end 86 which protrudes from the metal support member 200.

  In this way, the coloring matter can hardly be

  emulate on metal support members. In the embodiment considered, the angle a is equal to 55 as

  indicated previously. Other angles may be appropriate

  the particular position of the detacher element by

  relative to the photosensitive surface of which the sheet is

lifted.

As previously indicated, the detachment member 62 is preferably mounted so that it can move in a direction perpendicular to the normal displacement.

  of the photosensitive surface, parallel to this surface.

  In the embodiment shown, this movement is

  in the direction parallel to the drum axis of the photo-

  copier. As the detailed description that follows,

  the sheet detachment member is reciprocated in reciprocating motion, in small distances transversely to the photosensitive surface, by resiliently pressing the member against an element forming an open lateral cam which is progressively rotating around of its axis. In this way, the element represented 62 under

  shape of a blade pushed back by a spring, moves

  to the photosensitive surface by precisely set small increments approximately equal to twice the width of the blade. In addition, in an advantageous embodiment of the invention, the displacement of the blade takes place beforehand.

  collection of each leaf and in particular the movement

  progressive movement of the blade transversely to the surface

  takes place during the breeding cycle but before

  removal, that is, the blade is moved close to the

  start of each reproduction cycle. In other

  embodiments of the invention, the blade can be

  held in each fixed position for a predetermined number of operations, for example, a number of reproduction cycles greater than one, and can be moved whenever this limit is reached. When the 1i = ite frozen

  is temporal, the detachment element can remain at a location

  given for a fixed time of operation got not during a given number of cycles). In addition, the elementary displacement may be larger or smaller.

  that of the embodiment described.

  As the blade moves at the beginning of each cycle of reproduction, it appears that, during the usual duration of a drum, which corresponds to more than 100,000 copies, a limit beyond which the blade can not be moved in the same direction, must be reached, even if the distance of movement is low. In fact, in this advantageous embodiment of the invention, this limit is set to a value approximately equal to 7.5 mm. So,

  when the blade has moved in a direction of about 7.5 mm

  it changes direction (by proper change of the surface of the side-sided cam which regulates the displacement of the blade in the embodiment shown) and the

  blade then moves in opposite directions. In addition, according to

  tion and as described in more detail in the following

  memory, we obtain a better adjustment of the movement of the blade by displacement of the latter in interleaved form.

  that is, the positions occupied by the blade when

  that it moves in one direction are nested between

  positions it occupies when moving in opposite directions

  se (as shown in Figure 12).

  Referring now to Figures 8 and 9 in which the position of the detaching assembly is adjusted by the position of the surface 201 of an open side cam 202. This cam 202 is fixed to a threaded hollow shaft 204 at one end. 205 the keying end 207 of the shaft 204 carries a set 208 ratchet having a ratchet wheel 210 with two surfaces, fixed to the shaft by a screw 212. The cam 202 and the ratchet wheel 210 thus rotate together. The shaft 204 passes through an orifice 213 formed in a metal element 214 of the support frame, by a self-lubricating and leak-proof bearing 216,

and he turns in this hole.

  We first consider the mechanism for rotating the ratchet wheel 210 and more precisely the figures

  8 and 10; the rotational position of the wheel 210 is now

  naked by a series of circular cavities 220 that are es-

  periodically paced to the surface of an annular portion 222 of reduced diameter formed on the ratchet wheel 210. In the embodiment shown, the circular cavities 220 are placed every 180 so that there are 20 separate cavities around the circumference of the annular portion 222. An axis 226 attached to a shaft 228 pivoting about an axis 230, holds the ratchet wheel in position under the action of the force applied by a spring 232. A second arm

234 also pivots on the axis 230.

  The lever arm 234 is part of the actuation mechanism that rotates the ratchet wheel 210 to a next position (determined by the cavities 220). The arm 234 has a camming flange 236 which exceeds it and which

  is displaced in translation at the beginning of a reproductive cycle.

  by a cam control element 238, controlled

  in synchronism with the paper advance part of the

  mera. Thus, when the paper feed portion of the apparatus is operating, the element 238 represented by its outline

  in the figure, moves the lever 234 about the axis 230.

  As a result, a ratchet movement arm 240 moves

  this alternately and pulls, by its end 242 of trac-

  tion, a tooth 244 of the ratchet wheel 210. The resulting movement of the tooth 244 causes the wheel 210 to rotate about its axis 246 in the counter-clockwise direction in FIG. 8. As the wheel 210 rotates, the arm 228 is resiliently biased and in particular the axis 226 is driven radially away from the axis 246, when the arm 228 rotates clockwise about its axis 230. The axis

  226 thus enters a cavity 220. When the

  234 returns to its original position "de re, 0s", the ex-

  traction trough 242 "climbs" on the tooth 244. The axis 226 which is in the cavity 220, holds the ratchet wheel

in stable position.

  As shown in Figure 8, when the arm 240 moves to the left under the action of the arm 234 and rotates the wheel 210 in the counterclockwise direction, the arm 240 slides on a stud 248. When the organ 238 of the cam returns to its original position, the arms 234 and 240 are similarly urged back to their respective starting positions under the action of the restoring force of the spring 23. Thus, when the cam contact returns to this original position, the arm 234 rotates clockwise about the axis 230 and the arm 240 moves to a new cavity 250. The end 242 of the arm 240 which

  hook the ratchet wheel is tilted so that it

  place more easily over the tooth 244. The arm 234 has an elongated orifice 254 which allows movement of an axis 256 of the arm 240 when the end 242 rises above the tooth. A corresponding slot 258 of the arm allows the stud 248 to move. The entire ensemble

  259 & ratchet is carried by a metal plate

  than 214 of support, on studs 248 and 260. The arm 240

  is placed at a distance from the plate 214 which constitutes a

  261, 262. In FIG. 9, the cam 202 with lateral face rotates

  or moves in synchronism with the ratchet assembly 208.

  This cam is pushed against the metal support 214 by an end 263 of an elongate cam member 264 (FIG. 11) as will be described in more detail later in this specification. The cam 202 has, at its contact surface forming a support, an annular section 265 of reduced surface in contact with the member 214, along a small ring so that the friction in contact with the cam

  202 and the support 214 is reduced. In this way, the

  the friction between the cam and the forces of

  rotational drag is significantly reduced.

  The free face of the side cam 202 has a sur-

  very precise face 201 intended to move the detachment element

  leaf from one work position to another, on

  the surface of the drum. As shown in Figure 11, the

  seems of leaf removal is mounted so that it moves

  parallel to the axis of the drum. The distance between the

  detacher 62 and for example a fixed lateral member 280 of the frame of the copier, is controlled by the position of the

  lateral cam 202. The distance adjusting mechanism com-

  takes the flap 263 (Figures 9 and 11) which is pushed elastically in contact with the side cam at its cam surface 201. The cam contact 263 is integral with the elongate member 264 and is supported and guided by a sleeve 284 in which the member can slide in the direction of an axis 286. The latter is parallel to the axis of rotation of the drum. The sleeve 284 is screwed into a

  molded member 288 as indicated by reference 290. The

  molded handle forms a fixed surface element of the apparatus

  leaf removal. The elongated member 264 which is

  felt extends and supports one of the rolls,

  the roller 72, and is attached to the mounting bracket 60 of the applica-

  such a leaf detacher by an end cap 302

and a nut 304.

  A spring 306 is held between one end of the sleeve 284 and an elastic ring 308 attached to the element

  lying 264, in a groove previously formed in this

  ci for this purpose. Thus, the sheet removal apparatus elements are pushed down (in FIG. 11)

  so that the camming end 263 of the

  canism is pushed back against the free lateral face 201 of

the cam 202.

  During the normal operation of the mechanism of

  and forth, the ratchet wheel 210 progresses at the beginning of each reproduction cycle as previously described. The surface

  of the lateral cam is shown in FIG.

  angular position of the cam. (The curve looks like

  up and down stairs). It should be noted generally that the maximum displacement of the surface of

  cam is equal to a distance of two steps (it obviously exists

  differences and, in an advantageous embodiment,

  geux, one step is equal to 0.38 mm of displacement). The direction of rotation of the cam 202 does not have to be changed so that the movable element transversely returns to its original position. In an exemplary operation of the detachment portion of the sheet of the mechanism according to the invention, in an advantageous embodiment of the invention, the neck roll 64 comes into contact with the front edge of the print sheet, almost immediately after the detachment. from the anterior edge of the photosensitive surface, and the anterior border

  is then diverted and directed by the roll-neck into the envelope.

  take 98 of this roll and the roller surface 87

  led rubber. The roll, as indicated before

  previously, is pushed independently against the surface of the rubber roll and its position with respect to the photosensitive surface 15 and the end 86 is chosen so

  that the anterior edge of the detached leaf comes

  that immediately in contact with the roller 64 (Figure 3). The

  roll that is driven, in the embodiment of

  represented by the roller 74, directs the leading edge

  the sheet not only to the right-of-way 98 of the

  64 and 74 but also away from the stripper element

  62 (and end 86) so that the image adhering to the inside face

  the leaf can not be disturbed. For example, the tread roll 63 bears against the roller 74 with a force of 0.28 to 1.7 N, and is placed close to the surface 15, for example 1.6 mm thereof. Of this

  way, the roller 64 deviates much the sheet and the distance

  the paper-peeling element and to an advance mechanism so that the remainder of the paper is pulled away from the photosensitive surface and is directed and guided by the tread rollers 65, 70 and 72. These re-direct

  efficiently the sheet towards the post of fixing and pre-

  They keep it at a safe distance from an edge 100 of the mounting plate 60 (FIG. 4). (For example, the roll bears against the roller 74 with a force of

  0.56 to 2 N, and the rollers 70 and 72 are separated from the roll.

  water 74 from a distance of about 0.38 to 2.11 mm). Only the front edge of a print sheet must be able to come into contact with edge 100 if the fidelity of the image must be retained. In this way, the image

  which adheres to the leaf is not disturbed.

  In advantageous embodiments, the routers

  64, 65, 70 and 72 are rolled rollers which are not

  not the fragile image of coloring matter carried by the leaf. In other embodiments, the number of rollers used may be larger or smaller, and / or other moving surfaces, for example two belts, may be used to the extent that they do not disturb the developed image. by the sheet and o the function

  of the roll 64, which is to deviate substantially

  tantant the sheet and away from the detacher element 62, is obtained. Similarly, the roller 74 can

  be replaced by a belt or other moving surface.

  In the embodiment described above, the speed

  The surface 87 of the roll 74 is chosen to be slightly larger than the photosensitive surface of the drum 14. In other embodiments, the position and surface characteristics of the roll 64 are not required. are implemented so that the copy sheet is effectively separated from the detaching member 62. Thus, as shown in Figure 6, in another particular embodiment of the invention, the roller 74 is driven through of a slip clutch 102, at an angular speed which is sufficient for the

  peripheral surface 87 has a significantly higher velocity than

  re to that of the photosensitive surface. In this way, the copy sheet tends to wrap more tightly around the rubber roller 74 and is evacuated to

distance from detaching member 62.

  In the illustrated embodiment, a reciprocating detacher unit 48 is used at a marginal edge of the sheet to initially detach and seize a corner of the sheet and then direct it along a path Release. In other embodiments, a plurality of reciprocating assemblies 48 may be used, and may for example be spaced on

along the width of the drum.

  We now consider the advantages of the invention

  tion and its characteristics of non-obviousness. The device

  leaf detachment advantageously has a mechanism for pre-

  sheet removal for a photocopier and having few pieces, reliable, avoiding jamming

  paper by removing all the leaves in

  both of the photosensitive surface, especially the leaves

  duplicates, the apparatus being of simple fabrication and mounting

  from the technical point of view and able to use

  inexpensive so that its manufacturing price is low. In addition, the apparatus according to the invention does not soil the image carried by the sheet and does not deteriorate the photosensitive surface; moreover, it does not implement

  complex synchronization mechanisms for separa-

  of the sheet of the fragile photosensitive surface.

  The detachment element pushed back elastically, when

  it has suitable dimensions and a position, allows, in cooperation with the progressive transverse displacement, the formation of a mechanism in which the suppression of an image edge or even a small corner is not necessary

  and avoids undesirable deterioration of the surface area

  tosensitive, for practically the entire duration of

photoconductor.

  The various known sampling members are more complex and have no member that is always resting against the photosensitive drum. Known devices,

  described for example in the United States patent of

  that No. 3,649,115, are essentially precisely synchronized devices having mechanical structures

  precision to prevent deterioration of the sur-

  photosensitive face. The invention has the advantage of not requiring synchronization mechanisms which are in general very elaborate, for example controlled by cams

  or mechanically or electrically controlled, in

known.

  It should also be noted about these known devices in which a mechanical structure is maintained

  in contact with or rests on the photosensitive drum

  ci, that there is no device either which allows the formation of a reproduction on the whole surface or which advantageously implements a mechanism of deviation

  in cooperation ensuring a virtually

  tane of the printing sheet at a distance from the

  leaf to an exit path. Thus, the documents

  The known compositions do not describe either the method or the apparatus according to the invention. The various sampling members described in the known documents relating to reciprocating sensors (for example described in US Pat. Nos. 4,168,902 and 4,252,310) do not have

  organ that is still in contact with the photosensitive drum

  corn. In devices in which a mechanical structure

  that is maintained at least temporarily in contact with the drum.

  b for photosensitive or bearing against it and which further ensures a lateral displacement relative to the drum as described in the prior patent of the United States of America No. 4,252,310, no device allows a progressive and precise operation such as described under the command

  of a lateral cam, nor the positioning by axes

  putting a precise adjustment of the relative position of the blade

and the photosensitive surface.

  In addition, documents such as United States Patent Nos. 3,992,000, 3,885,786, 3,820,776,

  3,450,402, 3,578,859, 3,844,252, 3,938,950, 3,991,999,

  4,060,320, 4,072,307 and 4,261,560 describe neither the method

nor the apparatus according to the invention.

Claims (30)

CLAIMS Photocopier, of the type which comprises a movable member (14) having a photosensitive surface   1. sible (15), a device for forming a latent image developed on the photosensitive surface (15), a device (44) for advancing a drawing sheet (40) so that it is in contact with the photosensitive surface   a postponement (42) of the image developed on the sheet.   the drawing device, and a device (48) for removing the scanning sheet from the photosensitive surface, characterized in that the sheet removal device comprises a sheet detachment member (62) having a   active part pushed back elastically against the surface   tosensitive (15) and intended to be in contact with an   the interior of the sheet (40) as it moves towards the element   leaf detachment so that the front edge of the foil   it is detached from the photosensitive surface (15), a movable deflection surface (64) placed near the active part of the detachment element and intended to deviate substantially immediately the detached front edge away from the stripper element and to an exit path, this movable surface thus keeping the sheet out of contact with the detachment member, and a movable surface driving device (74) so that the sheet is deflected towards the travel path.   output and remote from the photosensitive surface.   2. Photocopier according to claim 1, characterized in that the deflection surface is the surface of a roll, and in that it comprises   a driven roller (74) which is in driving contact with   with the surface of the deflection roll, and an elastic member (90) for   active part of the sheet detachment element towards the over-   photosensitive face and in contact with it.   A photocopier according to claim 1, characterized in that it comprises a driven surface (87) which is in contact leading to the deflection surface, and the driving device drives the deflection surface or the driven surface at a speed higher   at the peripheral speed of the photosensitive surface <4).   4. Photocopier according to claim 3, characterized in that the drive device comprises a sliding element (102) for driving the driven surface to   a speed much higher than that of the surface area   tosensible. 5. Photocopier according to claim 1, characterized in that it comprises a driven surface (87) in contact with the deflection surface, and the driving device drives the deflection surface or the driven surface at a speed clearly   greater than the peripheral speed of the photo-   sensitive (15) so that the detached sheet is tensioned and is removed at a lower speed after being put under voltage.   6. Photocopier, of the type that includes   a movable member (14) having a photosensitive surface   ble (15), a device for forming a latent image developed on the photosensitive surface (15), a device (44) for advancing a printing sheet   (40) so that it is in contact with the photosensitive surface   to a transfer station (42) of the developed image on the printing sheet, and a device (48) for removing the printing sheet from the photosensitive surface, characterized in that the sheet removal device (48) includes a sheet detachment member (62) having a tip (86) resiliently biased against the photosensitive surface to contact an anterior edge of the pull sheet (40) as it moves toward the detachment element and that the front edge of the sheet is detached from the photosensitive surface (4), a deflection surface (64) mounted near the end (86) of the detachment element and intended to deflect the detached front edge to distance from the detachment member and to a right-of-way formed by the deflection surface (64) and a movable friction surface (82), and a device (102) for driving the deflection surface or the movable friction surface at least so that the drawing sheet transmitted in the right-of-way and directed to an exit route, away from the photosensitive surface.   7. Photocopier according to claim 6, characterized in that the deflection surface is that of a roller rotary deflection.   A photocopier according to claim 7, characterized in that the movable friction surface is formed by the surface of a driven roller (74), the deflection roller is a hollowing roll, and   a first (82) and a second (90) elastic element   that are intended to repel the end (86) of the element de-   leaf stain towards the photosensitive surface and the roughness   the water (64) to the friction surface.   A photocopier according to claim 8, characterized in that it further comprises a second hug roll (65), a device for mounting the sheet detachment member and the first and second hob rolls, and a third elastic device (93) for urging the second tread roll (65) toward the friction surface, the second tread guiding the draw sheet   from the right-of-way and along the exit path.   Photocopier according to claim 7, characterized in that the driving device drives the deflection roller or the friction surface or both at a speed   greater than the peripheral speed of the photosen-   sible. A photocopier according to claim 10, characterized in that the driving device comprises a sliding drive member (102) for moving the friction surface at a speed substantially greater than that of the photosensitive surface. Photocopier according to claim 7, characterized in that the driving device drives the roller   deflection or the driven surface or both at a net speed   higher than the peripheral speed of the photosensitive surface (15) so that the detached sheet is energized and pulled at a higher speed.   low when the sheet has been turned on.   A photocopier according to claim 8, characterized in that it comprises a third (70) and a fourth (72) neck roll, these two rollers being separated from the driven roll (74) and being intended to guide the draft sheet along the exit path.   14. Photocopier, of the type that includes   a movable member (14) having a photosensitive surface   sible (15), a device for forming a latent image developed on the photosensitive surface (15), a device (44) for advancing a printing sheet   (40) so that it is in contact with the photosensitive surface   to a transfer station (42) of the developed image on the printing sheet, and a device (48) for removing the printing sheet from the photosensitive surface, characterized in that the sheet removal device (48) includes a sheet detachment member (62) having a tip (86) elastically urged between the photosensitive surface to contact an anterior edge of the sheet   (40) as it moves towards the   and that the leading edge of the print sheet is detached from the photosensitive surface (15), a rotatable roll (64) having a fluff surface adjacent the end (86) of the detachment member to   the detached anterior edge is deviated in a practical way   instantaneously away from the detachment member (62),   the fluffy surface holding the flip-flop   of the stripper element, a roller (74) having a friction surface (87)   juxtaposed with the smooth surface and intended to grip   pressing the deflected anterior edge of the pulling sheet (40) and guiding the leading edge along an exit path, and a device (102) for rotating the roll at a speed sufficient to the developed image   worn by the print sheet is not soiled.   Photocopier according to claim 14, characterized   in that it comprises a first (82) and a second (90) element   elastically designed to repel the tip respectively   from the sheet detachment element to the photosensitive surface   sible roll and the roll to the friction roll.   A photocopier according to claim 15, characterized in that the driving device drives the roller (74) at a speed greater than the peripheral speed of the photosensitive surface, and it comprises a plurality of rolled rollers (65, 70, 72) of drawing sheet guide, each roll being mounted in working position in front of the surface of the roll (87).   A photocopier according to claim 16, characterized in that it comprises at least two draw sheet guiding rollers one of which (65) is resiliently biased in cooperation with the surface of the friction roll and a second (70, 72) is remote from this surface of the roll and is not to his touch.   The photocopier according to claim 15, characterized in that it comprises a device for mounting the sheet removal assembly on the path of the marginal edge of the drawing sheet. 24987-78   A photocopier according to claim 15, characterized in that the sheet detachment member comprises a planar member (62), and the sheet detachment assembly further comprises a device for mounting the planar member in a substantially plane direction.   perpendicular to the photosensitive surface.   Photocopier according to claim 19, characterized   in that the planar member has a composition based on "Mylar".   21. Method of removing a printing sheet (40)   of the photosensitive surface (15) of a photocopier,   being of the type which comprises a device for forming a developed image on the photosensitive surface (15), a device (44) for advancing the printing sheet so that it is in contact with the photosensitive surface   a post (42) to postpone the image developed on the sheet.   the drawing device, and a device (48) for removing the printing sheet from the photosensitive member, said method being characterized in that it comprises the elastic return of a sheet detachment member (62) by its end (86) against the photosensitive surface so that it contacts an anterior edge of the pull sheet (40) as it moves toward the sheet detachment member, detaching the leading edge of the printing sheet (40) of the photosensitive surface using the tip (86) of the sheet detachment member,   the almost immediate deviation of the ante-   loosely detached from the leaf and keeping this edge   the detachment member (62) and along an exit path, and   driving a movable surface (64) from   drawing of the distance sheet from the photo-   sensing and detaching member and to the exit path.   22. The method of claim 21, characterized in that it comprises the direction of the detached drawing sheet and deflected between a plurality of guide rollers (65,   , 72) so that it reaches an exit path.   23. The method of claim 21, characterized in that the driving step comprises driving the deflection surface by a led surface (87) placed in contact with it, the deflection surface and the driven surface.   forming a right-of-way intended to receive the   rage. 24. The method of claim 23, characterized in that the driving step comprises driving the driven surface at a speed greater than the speed of the photosensitive surface.   25. Photocopier, of the type that includes   a movable member (14) having a photosensitive surface   sible (15), a device for forming a latent image developed on the photosensitive surface (15), a device (44) for feeding a printing sheet (40) so that it is in contact with the photosensitive surface. (15) at a transfer station (42) of the developed image on the printing sheet, and a device (48) for removing the printing sheet from the photosensitive surface, said copier being characterized in that the device removal includes a sheet detachment member (62) having a   active part (86) elastically pushed against the over-   photosensitive face (15) so that it contacts an anterior edge of the pull sheet (40) when   moves to the leaf detachment element, and that it de-   stain the front edge of the print sheet of the   photosensitive face, and a drive device of the detachment element so that this element is displaced in a direction substantially parallel to the photosensitive surface, said training device comprising   a first circumferential surface having several   different positions (220) whose functions are   nexes and maintaining a positioning surface (201)   at several successive selected positions.   a device (61) for connecting the element de-   (62) to the positioning surface during operation.   in order to move the element in the direction intended for its displacement, a cam drive (259) for driving a second circumferential surface so that the detachment member is moved to a new position relative to the surface. photosensitive, and   a device (238) for controlling the device   camming after a predetermined limit has been reached. 26. Photocopier, of the type that includes   a movable member (14) having a photosensitive surface   ble (15), a device for forming a latent image developed on the photosensitive surface (15), a device (44) for feeding a print sheet (40) so that it is in contact with the photosensitive surface at a transfer station (42) of the image developed on the print sheet, and a device (48) for removing the printing sheet from the photosensitive surface, said copier being characterized in that the device removal comprises a sheet detachment member (62) having an active portion (86) resiliently biased against the photosensitive surface (15) and arranged to contact an anterior edge of the print sheet (40) as it advances toward the sheet detachment member and detaching the anterior edge of the printing sheet from the photosensitive surface, and a detachment member driving device so that this member is moved in a direction substantially parallel to the phoInsensible surface; driving device comprising a cam (202) having a plurality of separate surfaces (220) for determining positions having related functions so that a cam surface (201) is maintained at a plurality of selected successive positions, an elastic device (306) for biasing the detachment member in the direction of its movement against the cam surface, a driver (259) connected to a second set of position-holding surfaces for driving the cam so that the element detacher be moved   towards a new position in relation to the photosen-   a device (238) for actuating the training device when a predetermined number of copies has been been executed.   A photocopier according to claim 26, characterized in that the sheet removal device comprises a movable deflection surface (64) located near the active portion of the sheet detachment member and for substantially immediately deflecting the an anterior edge detached away from the detachment member and to an exit path, the movable surface thereby holding the pulling sheet out of contact with the sheet detachment member, and a second driving device (74) for driving the moving surface so that it deflects the pull sheet to the exit path and away from the photosensitive surface. 28. A photocopier according to claim 27, characterized in that the cam comprises a plurality of discrete surfaces (201) having associated functions and forming the cam surface, and the surfaces are arranged successively about a circumference of the cam, each surface having at least one neighboring surface such as the distance between the associated force surfaces, in the direction of travel,   is at least twice the width of the element leaf hunter.   The photocopier according to claim 28, characterized in that the device further comprises an elongate support member (264) having a longitudinal axis parallel to the direction of travel,   a device (302, 304, 60) for mounting the element   sheet detacher in spatial relation determined with respect to the elongated member, a device (280, 284, 288) for positioning said elongate member to cooperate with the cam surface, and the elastic device for pushing an end   (263) forming the flange of the elongate member against the sur- cam face.   30. Photocopier according to claim 26, characterized   in that the cam surface (201) has a plurality of surfaces   these distant and connected successively, having a configura-   staircase so that the detachment element is moved   in positions forming an interlaced pattern.