JPS6245554B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a means to improve the meltability of a meltable material by compensating for changes between the speed for transfer and the speed for welding of the support surface before the transfer of the image of the fusible material is completed. The present invention relates to an electrostatographic image reproduction machine in which an image of a similar material can be welded to a support surface.

An image pattern of dry, powdered, unfused toner material is transferred to a final image-bearing surface, such as from an initial support surface, such as a toner-developed charged receiver surface, to a copy sheet. In electrostatic transfer processes such as transfer electrophotography, the transferred toner only loosely adheres to the final support surface after transfer, and this toner is removed during the process of stripping the final support surface from the initial support surface. This toner is also easily disturbed by the process of transporting the final support surface to a toner user station. The final support surface passes through a user station as soon as possible after transfer to permanently fuse the toner image to the final support surface, thereby protecting the toner image from being smeared or disturbed by mechanical agitation or electric fields. Preferably, it is designed to prevent For this reason, and to simplify and shorten the copier paper path and save space, it is desirable to keep the user station as close as possible to the transfer station. A particularly preferred user station is a roll-type user in which the copy sheet is passed through a pressure nip between two rollers, at least one of which is heated and at least One is considered to be elastic. Examples of this type of xerographic transfer, stripping, transport and user equipment are available at
No. 3,578,859 issued May 18, 1971 to Stallings. These and other references cited herein are incorporated by reference.

However, if such a user roll nip for the final support surface is located sufficiently close to the transfer station that the leading portion of the final support surface is within the user roll nip while the trailing portion of this same final support surface is A serious problem arises if the light is still allowed to be in contact with the photoreceptor, and it is to this problem that the present invention provides a solution. This problem is that the unfused toner image transferred or being transferred to the trailing edge of the final support surface becomes smeared or falls off. This condition is caused by relative movement or slippage between the initial and final support surfaces; in these areas these surfaces are in contact, i.e. these areas of the final support surface It has not yet been stripped away from its initial supporting surface. The cause of such slippage is a velocity mismatch between the surface velocity of the initial support surface and the nip velocity of the fuser roll (the velocity at which the fuser pulls the leading edge of the paper past it). If the user roll nip speed is slower, the final support surface can slide in the backward direction relative to the initial image support surface. If the user roll is faster, the final support can be pulled in the forward direction relative to the image on the initial support surface. In either case, this causes the aforementioned smearing, or shedding of the toner image transferred to the trailing edge region of the final support surface, or stretching of the image.

Maintaining exactly equal speed drive between the initial support surface and the user roll is difficult. Still further, there is the complication that the actual sheet drive speed of the user roll nip varies with changes in the effective diameter of the nip's drive rolls. This can occur due to roller replacement, and it also changes in the elastic deformation of the rollers due to applied nip pressure, material aging, temperature effects, and other changes. In commercially available devices, it is difficult to maintain equal speeds between the user roll nip and the receiver surface, and maintaining equal speeds increases maintenance requirements and requires speed adjustment mechanisms. do.

If the space between the user station and the transfer station is larger than the copy sheet dimensions, and if separate two-speed sheet transport is performed between the station and the transfer station, the user roll nip may Different speeds to G.A. Mahama February 26, 1974
As in U.S. Pat. However, this has the notable disadvantages of requiring extra space, increasing the number of processing steps for sheets with unfused images, and being complex and expensive due to the extra transport mechanism.

In electrostatographic reproduction technology, a copy sheet is moved through a copier to another location,
It is also known to form slack in order to perform other functions. For example, creating slack in the copy sheet by interfering with forward movement of the copy sheet by registration fingers and continuing to feed the copy sheet by a forward feed roller;
Aligning the leading edge of a copy sheet before it is fed to an image transfer station is described, for example, in U.S. Pat.
Known in No. 3601392. The creation or pre-forming of slack in the web material of copying material to compensate for damping of the web material during cutting operations, such as when the web is cut into individual sheets, has been described, for example, by Alan F. It is known from US Pat. No. 3,882,744, granted May 13, 1975. The latter patent also shows that the copy web material is preformed into the shape of an initial convex sag covering the aperture surface, and that when the web is stopped in the forward direction of the sag, air pressure is used to inflate the sag. Indicates that it is used.

U.S. Pat. No. 3,744,907, issued Nov. 27, 1973 to Stefan Borostyan, discloses a method for removing a copy sheet from an initial image support member and for feeding a copy sheet to a roll user and Discloses a vacuum sheet stripping device in which the sheet has a convex shape.
A vacuum member is utilized that has a rotating cylindrical aperture to which the copy sheet is attracted. During this period of rotation of the vacuum member, the vacuum is automatically shut off to the vacuum stripping member to release the copy sheet.

R.K. Reinbach and others 1970 4
U.S. Pat. No. 3,508,824, issued May 28, describes a conductive curved guide plate for attracting a copy sheet in a stripping area and guiding the copy sheet to a user station.

The present invention provides an apparatus for compensating speed disharmony;
This apparatus allows the user roll nip to be closely spaced from the transfer station of the electrostatographic copier at a distance less than the kinematic dimension of the individual copy sheets, and such apparatus This makes it possible to provide the above-mentioned advantages of a device and also to eliminate the above-mentioned disadvantages of such a device. The intermediate portion of the copy sheet is selectively supported and guided in such a manner as to permit a speed difference between the user roll nip speed and the initial support surface speed. Variations and differences in velocity are allowed between leading and trailing edges of the same final image bearing surface in such a way as to avoid disturbing the unfused toner image in any area on the final image bearing surface.

Other objects, features and advantages of the invention relate to special devices, steps and details for achieving the above-described concepts of the invention. Accordingly, the present invention may be better understood by reference to the following description of exemplary embodiments thereof, and by reference to the drawings, which form a part of this description and which are approximately to scale. will be done.

Now, if you refer to the drawings, especially Figures 1 to 3.
Referring to Example 10 of the Figure, the xerographic transfer stripping, vacuum manifold transport and roll user equipment shown therein is shown in our 4000 and
It can be seen that it is overall similar in many respects to the 4500 copier. The foregoing disclosures of US Pat. No. 3,578,859 or its related patents or other references further describe suitable conventional detailed examples of such devices. Accordingly, the following description is directed specifically to novel aspects of embodiments that compensate for the velocity disharmony described above.

However, to begin with a brief description of the general appearance of the apparatus 10 depicted in FIG.
The sheet 12 is continuously conveyed in contact with the initial image bearing surface 14 of the moving photoreceptor drum 16, and
It can be seen that it is transported at the same speed as . copy·
The sheet passes under a transfer corona generator 18 which applies an electrostatic transfer charge to the back side of the copy sheet and transfers the copy sheet to the light receiving surface 14.
Electrostatically adhere to the surface. The copy sheet 12 is then transported over the light receiving surface 14 below the static neutralizing corona generator 20, which generates a transfer onto the copy sheet by means of radiation, preferably alternating current corona radiation. Substantially reduces charge. The leading edge of copy sheet 12 is then stripped from light receiving surface 14 by mechanical stripping fingers 24 . (It should be understood that other stripping devices may be provided). Copy sheet leading edge 2
The stripping position of 2 is started as shown here by the dotted line position 22a.

As soon as the leading edge 22 of the copy sheet is peeled away from the photoreceptive surface 14, the copy sheet is attracted to a generally planar, smooth, stationary guide surface 26, shown in bottom view in FIG. 26. As shown by the solid line position of the copy sheet 12, the copy sheet 1 is brought into intimate and conformable contact with the guide surface 26.
It can be seen that guide surface 26 includes a plurality of vacuum apertures 30 capable of attracting and retaining 2.

The intermediate portion of the copy sheet 12 that is behind the leading edge of the copy sheet with respect to the surface 14 (the portion that changes)
The continuous electrostatic deposition of the particles provides a driving force to the copy sheet 12. The copy sheet is driven forward (downstream) at a speed equal to the speed of the light receiving surface. The copy sheet 12 slides in the forward direction over the guide surface 26 and then through a sheet guide member, such as the guide 32 shown here, toward the nip 34 of the roll user unit 36. The guide 32 is for correctly introducing the leading edge 22 of the copy sheet that has left the guide surface 26 into the nip 34. Without the guide 32, the leading edge 22 of the copy sheet in a free state would be inserted into the nip 34.
may collide with either roll of the roll user unit 36 and disturb the unfused toner image. Since the copy sheet has a certain degree of rigidity, if the guide surface 26 is tilted so that the leading edge of the copy sheet that has left the guide surface 26 is slightly in contact with the lower surface of the guide 32, the copy sheet The leading edge of the sheet is forcibly guided along the lower surface of the guide 32 to ensure that it is guided into the nip 34. The leading edge of the copy sheet that leaves the guide surface 26 may sag to some extent, and the guide 32
Without this, it is difficult to reliably guide the leading edge of a free copy sheet into the nip 34. Therefore, a design in which the guide surface 26 is made slightly more inclined, the leading edge of the copy sheet is first slightly brought into contact with the lower surface of the guide 32, and then the copy sheet is forcibly guided along the guide 32 to the nip 34 is proposed. Do it. Therefore, if the manifold guide surface 26 or an extension thereof extends close enough to the user roll nip, no additional guide 32 is needed. In the solid line position of the copy sheet 12 shown in FIG. 1, the copy sheet is shown with its leading edge 22 just entering the user nip 34. In this position, copy sheet 1
2 is seen to fully engage and contact substantially the entire guide surface of the vacuum manifold unit 28.

Now, considering some of the significant differences between device 10 and prior art devices of this type, the relationship between the drive speeds of user nip 34 and photoreceptor drum 16 must be discussed first. A common mechanical direct drive connection 38 is shown between one axis of the user roll and the axis of the photoreceptor drum 16. However, rather than designing linkage 38 to provide user roll nip 34 with a surface velocity equal to the velocity of photoreceiver surface 14, drive linkage 38 is configured to
The configuration is such that the pulleys or gears have suitably different diameters to provide a speed to the user roll nip that is slightly less than speed 4. In this way, copy sheet 12 is transferred to user nip 3.
4, the leading edge 22 of the copy sheet moves in the forward direction at a slightly slower speed than the intermediate and trailing edge regions of the same copy sheet are advanced in the forward direction by the receiving surface 14. . This creates the potential for slippage between copy sheet 12 and surface 14, causing smearing or shedding of the toner image. To prevent this, the intermediate portion of the copy sheet 12 between the user roll nip and the transfer station is provided with a low mechanical resistance to the vacuum manifold unit guide surface 26.
Apparatus 10 includes means for forming a slack or bridge portion away from the substrate. This sag or bulge is free to expand to its maximum position to take on and absorb the entire accumulated velocity difference across the copy sheet 12 until the trailing edge 23 of the copy sheet is separated from the photoreceptive surface 14. is possible. This slack or bridge portion of the copy sheet 12 is located at the dotted line position 12' in FIG.
It is shown by. Copy at position 12'
The positions of the leading edge and trailing edge of the sheet are 2 each.
Shown at positions 2' and 23'. For a fixed, generally planar guide surface 26, the sag is always convex and expands to become more convex as the copy sheet advances. The loosely toner image bearing side of the copy sheet faces away from vacuum manifold 28.

In this apparatus 10, the velocity disharmony is compensated for by the slack created by the receding copy sheet behind the slow user roll nip, and the slack is compensated for by the generally planar guide. Because it expands away from the passage 26,
The minimum dimension sag can be increased to compensate for the increase in velocity disharmony, and can be decreased to compensate for the decrease in velocity disharmony. Thus, this speed difference between the user roll nip and the photoreceptive surface is not significant and varies during operation, resulting in changes in the radius of the driven user roll, the leading edge of the copy sheet, etc. and trailing edges, etc., can be accommodated. The speed of the user roll nip should be set above any normal operating range or at a somewhat higher speed sufficient to compensate for changes, including changes that increase the speed of the nip (therefore always a minimum seat). It is preferable that the preset is such that it always provides a curvature. This allows the driving of a fixed, non-critical user roll that does not need to be adjusted to the driving of the receiving surface.

A sheet detector 40, of the suitable conventional mechanical switch (or optical) type shown here, is provided in the path of the copy sheet 12 when the leading edge 22 of the copy sheet is in the user roll nip 34.
2 is an example of a device that electrically indicates when the device was first held by As shown in FIG. 1, switch 40 is positioned within the vacuum manifold;
A switch finger 41 for actuating the switch passes through the bottom or guide surface 26.
Finger 41 is normally located in the path of the copy sheet and is moved by the passage of leading edge 22 of copy sheet 12 from the dotted line position to the solid line position shown. A delay circuit 42 is used to provide an electrical output signal after a period corresponding to the time required for the leading edge 22 of the copy sheet to be driven from the position of the switch finger 41 to the user nip.
can be used. The switch can be placed at various other locations along the path of the copy sheet. Alternatively, other available mechanical logic signals may be used instead, such as signals derived from the logic unit of the main cam bank or copier.

The controlled sag is created in the copy sheet without disturbing the toner image and without exerting forces on the copy sheet that would cause it to slide on the light receiving surface 14. This is accomplished here by the novel construction and operation of the vacuum manifold unit 28. first second
Referring to the figure, vacuum manifold unit 2
It can be seen that 8 comprises a one-piece metal casting or the like having a top cover 44, which is shown removed in FIG. 2 for clarity. FIG. 2 is a view from above of the vacuum manifold unit of the apparatus 10 shown in FIG. 1, with the right side of FIG.
The left side of the figure is inverted so that it is located on the right side of FIG. Internal dividing wall or vertical wall 4
6 extends the entire length inside the manifold,
The manifold is divided into two separate air chambers 48 and 49. The wall 46 extends approximately in the center of the lower guide surface 26 of the vacuum manifold, but slightly in a forward direction from the center and across the paper path. Both air chambers 48 and 49 have vacuum openings therein for holding the copy sheet, but at the first forward edge of the guide surface 26 such that the copy sheet is initially held by the vacuum manifold unit. It is preferred that the forward air chamber 48 has a greater number and larger diameter vacuum openings than the aft air chamber 49 along the . (See Figure 3). 3 is a view from below of the vacuum manifold unit of the apparatus 10 shown in FIG. 1, and the copy sheet advances from the right side to the left side in FIG. The two arms shown protruding to the left in FIG. 2 and to the right in FIG. 3 are for attaching the transfer corona generator 18 and static elimination corona generator 20 shown in FIG. be.

As shown in FIG. 2, vacuum is applied to the vacuum manifold unit 28 from a single vacuum pump 50, which is a simple axial fan or centrifugal blower motor unit. A suitable vacuum level inside the vacuum manifold is, for example, approximately 3.81 cm (one and one-half cm) of water column.
inches) or 3.8 g/cm ² . In this configuration, the vacuum pump 50 can be located at any suitable location within the machine and may be connected to the rear wall of the vacuum manifold unit, for example by a vacuum conduit 52. However, the vacuum connection is
It is important to note that only exists for 8. Wall 46 is formed to isolate the vacuum input from rear air chamber 49. The only connection between the two air chambers, hence the rear air chamber 49
The only source of vacuum for the airflow is through an airflow restriction slot 54 in the center of wall 46, as seen by the arrows indicating the airflow pattern in FIG.

With this vacuum arrangement, the vacuum is in the front air chamber 48
It can be seen that the internal vacuum opening 30 is held at all times and therefore always at the internal vacuum opening 30. This always prevents the copy sheet from falling off or sagging from the guide surface 26 of the vacuum manifold in the area of the front air chamber 48. In this manner, the toner image bearing surface of the copy sheet is prevented from contacting the stripping finger 24 or the light receiving surface at any time, and the path of the paper from the light receiving surface to the vacuum manifold is consistent. That is, after initial leading edge stripping, the path of the paper between the region where the body of the copy sheet is stripped from the receiver and the vacuum manifold is constant, and the shape of the backward region of the vacuum manifold surface and It is maintained by space. In this manner, once the leading edge of the copy sheet is captured by the vacuum manifold, the position at which the copy sheet is stripped from the receiver surface is changed and movement is prevented. This is important to prevent changes in the charge level of the copy sheet during the stripping step.
This is because the stripping stage uses static elimination corona generator 20.
This is because it takes place during the operation of

In contrast, as discussed below, the vacuum in the rear air chamber changes periodically during machine operation for each copy sheet. In particular, the vacuum pressure in air chamber 49 acting on the copy sheet is effectively removed for such a period that it is desired to form a speed compensating slack or bridge 12' in copy sheet 12. That is, the vacuum force is removed from the vacuum openings 30 in the forward half of the vacuum manifold, allowing slack to build up freely in the forward and not reverse directions of the manifold, and during slack formation, the vacuum forces are prevented from acting on the sheet in the desired sag region 12'. Also with this configuration, sag formation is facilitated by gravity such that the weight of the sheet in the sag region pulls the sheet in the forward direction away from the vacuum manifold and other guides 32. The formation of sag over such a large area is not prevented either pneumatically or mechanically, but rather is promoted. However, rearward expansion of the sag area is prevented by continuously holding the leading edge of the copy sheet against the vacuum opening 30 of the forward air chamber 48. By creating slack in the copy sheet, no substantial slipping forces are generated and transmitted through the copy sheet to the portion of the copy sheet that is in contact with the photoreceptor.

Referring to FIG. 1, the aforementioned rear air chamber 49
Periodic removal of vacuum from the air is accomplished by quickly actuating the bleed valve 56 by an electric solenoid 58. Paper detection switch 4
By receiving a suitably timed electrical signal, shown here by zero delay circuit 42 and solenoid 58, solenoid 58 is actuated to lift bleed valve 56 to the position shown in dotted lines; Thereby the manifold top cover 44
The air bleed opening of the tank is opened to the atmosphere (see Figure 2). As shown by the dotted airflow arrows in FIG.
It allows you to quickly drop it. Vacuum connection slot 5 through the wall of wall 46 between the two air chambers
4 continues to evacuate the interior, but this restriction slot 54 is very small compared to the bleed opening 60, so when the bleed opening 60 is opened by the bleed valve 56, it will evacuate the air chamber 49. You won't be able to do that. Although the relative proportions of areas shown in the drawings are suitable examples of relative values of these total areas, the shape, location, and spacing of the openings may be varied as desired.

When the solenoid 58 is not actuated, i.e. when the bleed valve 56 is closed, vacuum is applied from the vacuum blower 50 through the first air chamber 48 and the slot 54 in the wall 46, bringing the vacuum pressure level in the air chamber 49 to the air chamber 48. The vacuum pressure level is equivalent to the vacuum level of . The air flow restriction formed by the slot 54 or other suitable opening between the two air chambers may sufficiently restrict the air flow compared to the total air flow provided by the vacuum pump 50. The vacuum pressure in the air chamber 48 increases when the solenoid 58 is activated.
are not significantly affected by sudden loss of vacuum. However, if desired, a high vacuum can first be applied to the forward air chamber 48, for example by a blower of the same size, to facilitate the vacuum stripping stage.

If the copy sheet 12 covers the first large vacuum opening 30 along the leading edge of the vacuum manifold, this reduces the airflow drawn by the air chamber 48 through the vacuum opening 30. If you wish,
As the copy sheet moves in the forward direction from the area of the front air chamber 48, it can increase the vacuum pressure available to the rear air chamber 49.

It is desirable to maintain vacuum retention across the guide surface 26 of the vacuum manifold until the leading edge 22 of the copy sheet moves across the vacuum manifold and enters the nip 34 of the user roll. In particular, if this leading edge has a pre-formed tendency to curl up away from the guide surface of the manifold, the leading edge may
It is particularly desirable to maintain all the vacuum retention force on the leading edge of the sheet as it passes across the guide surface 26 of the sheet. In this way, the leading edge area of the copy sheet is fully supported by the receiver until it is guided to the user. It is desirable to remove the vacuum support from the copy sheet only after the leading edge of the copy sheet has been captured or supported by the user nip 34. Also copy/
The speed mismatch problem does not occur until the sheet reaches the user nip. The guide surface 26, which is preferably planar in shape, smoothly impedes the forward movement of the copy sheet 12 to a position as indicated by the solid line position of the copy sheet 12 in FIG. It gives a straight path.

When the leading edge 22 of the copy sheet 12 reaches the user nip 34, the bleed valve solenoid 58 is activated quickly to open the air chamber 49 to the atmosphere and cause the copy sheet to clear the bottom of the air chamber 49. allowing it to fall off i.e. bend. Because the user roll nip preset effective linear speed is slightly slower than the receiver drum speed, the copy sheet begins to sag and accommodate this speed disharmony. However, as previously discussed, the vacuum in the forward air chamber 48 is maintained, allowing sag to form between the user roll nip and the area near the vacuum bulkhead 46.

This condition persists while the copy sheet is fed forward through the nip. That is, the solenoid 58 holds the bleed valve 56 open and the sag continues to expand until it reaches its maximum sag position, which is the amount of velocity disharmony that the sag must absorb and the delivery. determined by the length of the copy sheet to be used.

Next, the trailing edge of copy sheet 12 is at position 2.
3' (i.e., as soon as the trailing edge of the copy sheet is removed from contact with the photoreceptive surface and before the trailing edge passes over the support surface of the front air chamber 48), the solenoid 58 release and close the bleed valve 56, thereby opening the aft air chamber 49.
Apply vacuum pressure again. This ensures that the trailing edge region of the copy sheet is held against the guide surface 26 below the rear air chamber 49, preventing any backward movement that could cause interference with the loose toner image on the copy sheet. The rear area of the copy sheet is prevented from bouncing back, falling off, or curling, i.e., the rear area of the copy sheet is placed over the entire vacuum manifold unit 28 and into the path of the copy sheet. This means that it will be retained.

The vacuum support force on the copy sheet still existing below the rear air chamber 49 is removed only to the intermediate region of the copy sheet where the desired slack is formed, and is removed from the leading or trailing edge of the copy sheet. It can be seen that none of these are excluded. If desired, the vacuum bleed valve 56 may be closed once the copy sheet exits the transfer zone below the transfer corona generator and before the trailing edge 23 of the copy sheet completely exits the receiving surface. It can also be seen that this same cycle repeats for each copy sheet.

Removal of the signal on solenoid 58 to reclose bleed valve 56 in response to stripping the trailing edge of a copy sheet from the photoreceiver is coupled to a suitable circuit, such as a delay circuit, for copying paper in the paper path. - Controlled by the sheet trailing edge detector. Alternatively, the delay time itself is preset based on a machine set signal responsive to the size of the copy sheet being used in the direction of the paper path.

Other features described herein relate to different desirable stripping positions of the leading edge of the copy sheet relative to the main portion after the leading edge of the copy sheet. In FIG. 1, the actual corona radiation member (wire) 21 of the static elimination corona generator 20 is connected to the receiver 16
A center line 62 is shown connecting the center line and the tangent line of. As mentioned above, the receiver surface 1
The position of the tip region of the vacuum manifold unit relative to 4 and its angle determine the angle and position of the copy sheet relative to the receiver surface and hence the actual stripping where the copy sheet is initially lifted away from the receiver. This is done so that the position, or line, can be controlled.

This stripping location is at or in close proximity to the center line 62 , i.e. at or directly adjacent to the actual corona emitting member of the static neutralizing corona generator 20 and of the ion emitting area of the static neutralizing corona generator 20 . It has been found that a central location is desirable. The conductive shield 63 of the corona generator 20 provides a discharge area on the copy sheet of substantially equal distance on either side of the corona discharge member 21. Of course, the power distribution is non-uniform, ie the actual ion current output increases as the corona emitting member approaches. This is because the corona radiating member is closest to the receiver and causes a higher electric field to act on the receiver in that region. If the stripping step is carried out under a static neutralizing corona member, while the static neutralizing process is in progress,
That is, the stripping step is performed before total charge neutralization occurs and while a substantial transferred charge still remains on the copy sheet from the front transfer corona generator 18.

However, it is important to note that this stripping position below the electrode 21 of the neutralizing corona generator is relative to the sheet body after the leading edge 22 has been stripped off, and not to the leading edge itself. . As shown by the dotted line position 22a of the leading edge at the first tip edge stripping position, this stripping position occurs after the tip edge has passed through the entirety of the static eliminating corona generator 20 and has been sufficiently exposed to the radiation of the static eliminating corona. It is desirable that the transfer charge is further sufficiently removed from the leading edge so that the leading edge can be completely neutralized more easily. The stripping finger 24 is positioned immediately aft of the neutralization corona generator 20 and directly below the forward (tip) end of the vacuum manifold unit 28, which front end forms the rear end of the neutralization zone. The stripping edge is closely spaced from the guide surface 26 and the trailing edge of the static eliminating corona generator 20 so that as little leading edge area of the copy sheet as possible is exposed to sufficient static eliminating radiation. It's summery. That is, the stripper quickly moves the leading edge up to the manifold guide surface 26 and thereby returns to the desired stripping position before the critical area of the copy sheet has passed beyond the neutralizing zone of the neutralizing corona generator 20. It moves to the position of .

It is important to note that in this apparatus 10 with a slow speed user roll, the vacuum manifold surface initially promotes convex deformation of the paper. That is, the shape of the copy sheet must initially be flat or slightly convex. This is because once the sag occurs in the opposite direction, it is difficult to change the direction of the sag in the sheet. The slightly convex area of the vacuum guide surface 26 is useful in initiating paper sag. Copy sheet sag provides the additional benefit that it increases the lateral beam strength of the copy sheet. This provides additional support to the copy sheet by providing firm contact under the guide surface.

If necessary, user role nip 36
The upper roll of the two rolls can be reoriented by moving its axis around the other roll in a more forward direction than shown. This provides extra space and gives the nip 34 a different orientation.

The entire unit described herein of a vacuum manifold with transfer and discharge corotron units mounted together is pivotable at one end but is capable of maintaining an adjustable fixed spacing from the receiver. It is preferably mounted to the xerographic apparatus in a conventional manner, such as by a three-point support arrangement with conventional screw-adjustable support pads on the machine frame. However, it is understood that these three units may be mounted separately if desired.

If desired, one or both ends of the integral unit or individual units may be placed outside the imaging area in sliding or riding shoes or rolls on a low friction drum that is stationary against the edge of the receiving surface. Therefore, it can also be supported directly from the light receiver surface. Photoreceptor drum riding supports are well known as other processing units in electrophotographic copiers. For example, U.S. Patent No. 11, 1975, issued to R.C.
No. 3,918,403 teaches a transfer corona generator having multiple rollers in contact with the backside of the paper during transfer. To Etsch O Ulrich December 5, 1961
U.S. Pat. No. 3,011,474, issued on Aug. The drum-riding mounting arrangement of the receiver allows the corona generator unit and/or vacuum manifold to maintain a preset, constant spacing relative to the receiver surface, independent of variations due to eccentricity or misalignment of the receiver or its support. make it possible to hold. However, the operating range of the unit can accommodate such normal tolerances for fixed mountings without the need to account for all relative motion between the unit and receiver.

It will be appreciated that vacuum may be selectively removed from selected areas of the vacuum manifold in other ways. For example, a sliding shutter can be used inside the bottom of the manifold to cover selected areas of the vacuum opening in the sheet guide surface. Properly setting the airflow will cause the shutter to selectively increase the vacuum pressure in the area of the opening that it does not cover, such as the leading edge or tear-off edge.

Now, if one considers the embodiments of FIGS. 4-6, it will be seen that there are many common parts that are commonly numbered. However, differences exist in velocity disharmony structure and operation. Regarding this apparatus 100, a vacuum manifold unit 10
2 has a concave outer shape on the guide surface 104. Additionally, roll user unit 36 is driven by a different drive combination 105 so that the speed of pulling the copy sheet at nip 34 is slower than in the embodiment of FIGS. 1-3. The speed of the light receiving surface 14 at the transfer station is greater than that of the light receiving surface 14.

The vacuum in vacuum manifold 102 is now also at least partially shut off and copy sheet 1
06 to move away from the manifold guide surface 104. However, as shown in FIG.
The copy sheet 106 is initially slackened by the vacuum holding the sheet, and the copy sheet 106 is pulled away from the guide surface 104 by overdriving the user roll nip 34 against the receiving surface. - The sheet 106 is now partially straightened at the dotted line 106'. That is,
The first curved surface of copy sheet 106 is
As long as a portion of the sheet remains above the receiver, it is pulled away from the vacuum shoe surface by the amount required to compensate for the velocity mismatch between the user and the receiver. Once the trailing edge of the copy sheet has left the receiver and support for the trailing edge has been ensured, the vacuum can be reapplied.

Vacuum manifold guide surface 104 with the same shape
The first elongated but shallow slack formed by the vacuum manifold 1, as shown in FIG.
02 by forming a concave surface of substantially uniform radius over substantially the entire bottom surface of the 02. The vacuum manifold 20 is not divided here into two separate air chambers having different vacuum levels during a portion of the machine's operating period. However, the front air chamber is small enough that the guide surface 1 under the rear air chamber
If it is considered that 04 has a sufficiently large curved surface, two chambers can be provided here as well.

Referring now to the vacuum system shown for this embodiment 100 shown in FIG. 5, the manifold itself is not provided with any air bleed. Rather, a butterfly valve 108, rotated centrally by a solenoid 110, is provided in the vacuum conduit 52 to quickly open and close the conduit to the vacuum source. However, the air bleed arrangement of FIG. 1 may also be provided here, assuming that air flow can be sufficiently restricted in the desired portion of manifold 102. The timing of activation of valve 108 by solenoid 110 for the leading and trailing edges of a copy sheet is similar to that previously described for the embodiment of FIGS. 1-3.

That is, a vacuum is applied to the vacuum manifold 102 for the entire guide surface 104 until the leading edge of the copy sheet is retained by the user roll nip 34. The vacuum is then quickly removed or reduced.

This allows the copy sheet to be moved with little mechanical or air resistance and therefore without pulling on the portion of the copy sheet that is on the receiver, thereby smearing the unfused toner image. User rolls the front portion of the copy sheet 106 at a faster rate than the trailing edge region is fed from the receiving surface 14 by pulling the extra length of the copy sheet out of the intermediate curved area. - The nip 34 is now ready to send. As soon as the trailing edge of the copy sheet 106 leaves the receiver, the valve 108 can reopen and provide vacuum support again to the copy sheet against the guide surface 104.

The speed difference between the user roll nip drive and receiver surface drive is set such that normal mechanical displacements or tolerances do not cause the user roll nip to be slower than the receiver. On the other hand, the preset user roll nip speed is so fast that if the longest copy sheet is used, all of the initial slack is
The trailing edge of the copy sheet is removed before leaving the receiver. There is a maximum speed difference that can be tolerated for a given length of copy sheet without removing all of the available first sheet slack. This is because if the sheet is pulled completely flat,
Second, the higher speed of the user roll pulls the entire sheet, including the portion in contact with the photoreceptor surface, at the same speed in the forward direction, and this higher speed also causes the problem of critical trailing edge toner smearing. It causes it. However, sufficient velocity compensation for normal machine tolerances provides only a slight concave displacement from the planar passage, from about 7.62 cm (3 inch) to 10.14 inch.
It has been found that this can be provided by a slack created in the sheet feed direction of 4 inches.
For example, velocity compensation is provided by a displacement of only 0.504 mm (0.02 inches), or by a semi-cylindrical surface with a larger radius, e.g. 19.05 cm (71/2 inches). This curved surface can be easily formed in manufacturing the vacuum manifold 102.

In this apparatus 100 using an overspeed user roll, the vacuum manifold surface 104 must first preform the paper into a concave shape, as opposed to the embodiment of FIGS. 1-3. It is important to note that the shape of the copy sheet must initially be flat or slightly convex. Once the sag starts in the opposite direction, it is very difficult to change the direction of the sheet sag.

Regarding the change in profile of the vacuum manifold 102 of the embodiment of FIGS. 4-6, the copy sheet leaves the guide surface 104 and the user nip 34
There may be a change in the approach angle of the copy sheet as it approaches. Also, the paper passage guide surface 10
4 is desired in order to increase the available slack space. If necessary, the two rolls of the user roll unit may be rearranged by moving the axes behind the top roll and around the other roll to provide extra space and allow for a different orientation of the nip 34. It is beginning to give.

It should be noted that the sagging of the copy sheet 106 provides the additional benefit that it increases the beam strength of the copy sheet. This provides additional support to the copy sheet from the contact beam portion below the guide surface 104.

The actual sag length area, or concave portion of the vacuum manifold guide surface 104, is determined by both the amount of velocity disharmony that can be expected and paper processing considerations. It is desirable that the length of the slack be as long as possible to provide maximum speed compensation. This is because, compared to a short sag, a longer radial sag reduces the sagging force, or force due to the beam strength of the copy sheet, that tends to cause the trailing edge of the copy sheet to slide forward on the receiver. . However, because it is desirable to keep the path length of the copy sheet to the user relatively short, this puts a practical limit on the length of the guide surface 104 in the direction of copy sheet feed, and Therefore, there is a practical limit to the length of the sheet slack that can be used.

The all-in-one unit shown here in both embodiments of the vacuum manifold with transfer and neutralization corotron units mounted together is a three-point suspension system with a conventional screw-adjustable support pad on the frame of the machine. Although it is pivotable at one end, it is preferably mounted to the xerographic apparatus in such a way that it can be maintained in an adjustable fixed position spaced from the receiver. However, it will be appreciated that these three units may be mounted separately if desired.

If desired, one or both ends of the integral unit or individual units can be mounted on a low-friction drum sliding or riding surface that rests against the edge of the receiving surface outside the area used for imaging. It can be supported directly by the light-receiving surface by a shoe or roll. Receiver drum riding supports are known as other processing units in electrophotographic copiers. For example, U.S. Pat. No. 3,918,403, issued Nov. 11, 1975 to R.C. Bock, teaches a transfer corona generator having a plurality of rollers that contact the backside of the paper during transfer. To Etsch O Ulrich
U.S. Pat. No. 3,011,474, issued Dec. 5, 1961, teaches a phenomenon electrode device with an attached receiver roll. The receiver drum riding mounting arrangement allows the corona generator unit and/or
The vacuum manifold can be held at a predetermined distance from the light receiving surface regardless of changes in the eccentricity or misalignment of the light receiver or its support. However, the operating range of this unit can tolerate such tolerances as are normal for fixed mountings without the need to account for all relative motion between the unit and receiver.

It will be appreciated that vacuum can be selectively removed from selected areas of the vacuum manifold in other ways, as shown in other embodiments for external vacuum manifold valves or flappers. For example, a sliding shutter can be used inside the bottom of the manifold to cover selected areas of the vacuum opening in the sheet guide surface.
With appropriate airflow, this can also selectively increase the vacuum pressure at the uncovered opening or leading edge or stripping area.

It will be appreciated that the invention may be used with many transfer and user device configurations other than those shown herein. For example, the additional sheet tensioning or motion damping device may be such as that disclosed in U.S. Pat. No. 3,893,760 to R.R. Thettu, issued June 8, 1975. This device was sold to Tay Meagher on December 1973.
As shown in U.S. Pat. No. 3,781,105, issued June 25, 1975, or U.S. Pat.
A pressure transfer roll may be used instead of the corona generator, and in these devices, the fuser
Closer spacing between the roll and transfer roll is desirable. U.S. Patent No. 8 June 1974 to R.P. Crowford
It is also possible to generate the desired vacuum force here by selectively acting different pressure nozzles to give a Bernoulli effect, as described in No. 3,784,190.

Various other stripping devices are utilized for the leading edge of the sheet. For example, if the air blower, vacuum stripper, or receiver is curved,
There are static electricity eliminators and the like that remove static electricity using only the strength of the sheet without any compensation.

With respect to the embodiment described herein, it is noted that the copy sheet is supported on a stationary guide member between the transfer station and the user station. This has the advantage of not requiring extra mechanisms and costly rotating sheet transport members. However, the described apparatus may also be applied to a copier in which a similar sag-controlling shuttable vacuum guide is provided on the non-fused side of the copy sheet. The surface allows the leading edge of the unfused copy sheet to be gripped by a mechanical gripper, vacuum belt or roller. Although this apparatus can also be applied to protect dry toner unfused images, the described apparatus is suitable for applications where a wet (undried) image on a copy sheet is removed from the original support surface. It can also be used in liquid image devices.

In conclusion, an improved image transfer device is described herein. Although the apparatus and steps described herein are preferred, it must be understood that many changes and modifications can be made by those skilled in the art without departing from the scope of the invention. The following claims are intended to cover all such changes and modifications that fall within the spirit and scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view of a typical electrophotographic copying apparatus according to the present invention, illustrating portions relevant to the description of the present invention. 2 is a top view of the exemplary vacuum manifold unit of FIG. 1 with the top cover removed to the right for clarity; FIG. Figure 3 shows
FIG. 2 is a bottom view of the vacuum manifold of FIGS. 1 and 2;
FIG. 4 is a side cross-sectional view similar to FIG. 1 of a different specific example. FIG. 5 is a top view of the vacuum manifold of the example shown in FIG. FIG. 6 is a bottom view of the manifold of FIG. 5. 12... Copy sheet, 14... Light receiving surface, 26...
Vacuum guide surface, 28... Vacuum manifold, 36...
Sheet transport device, 38...speed control device, 56...vacuum control device.

Claims (1)

Claims: 1. One side of the copy sheet from the initial image bearing surface to which an unfused image of imaging material moves as the copy sheet is superimposed on and moved with the initial image bearing surface. while a leading edge portion of the copy sheet carrying the transferred unfused image engages a rotating user roll nip spaced from said initial image bearing surface. , the trailing edge of this same copy sheet is still moving with the initial image support surface, and the copy
In a reproduction apparatus wherein a sheet is adapted to extend between the rotating user roll nip and an initial image support surface, a leading edge portion of the copy sheet engages the rotating user roll nip; The initial image support surface and the rotary frame are arranged such that the speed at which the leading edge portion of the copy sheet is moved is slower than the speed at which the trailing edge portion of the copy sheet is moved when the trailing edge portion is moving with the initial image bearing surface. user·
a speed adjustment device for moving the roll nip; and a speed adjusting device, which is planar or convex and positioned above the initial image support surface and between the initial image support surface and the rotating user roll nip. The copy sheet has a vacuum guide surface and a copy sheet is brought into contact with the vacuum guide surface, and the surface of the copy sheet opposite to the surface that supports the transferred unfused image is supported by vacuum pressure, and the copy sheet is a vacuum guide surface device for guiding a sheet to the rotating user roll nip; and reducing the vacuum applied to a portion of the vacuum guide surface proximate to the rotating user roll nip. a vacuum reduction device; activating the vacuum reduction device when a leading edge portion of a copy sheet reaches the rotating user roll nip;
The copy sheet is supported between the nip and the portion of the vacuum guide surface remote from the rotating user roll nip, allowing the copy sheet to sag downwardly therebetween, so that the trailing edge of the copy sheet is for deactivating the vacuum reduction device between the time the portion leaves the initial image support surface and the portion of the vacuum guide surface that is closer to the rotating user roll nip; A copying device comprising: a vacuum control device; 2. an unfused image of imaging material is transferred from the moving initial image-bearing surface to one side of the copy sheet as the copy sheet is moved in superimposition with the initial image-bearing surface; The leading edge portion of the copy sheet supporting this transferred unfused image also engages a rotating user roll nip spaced from the initial image supporting surface while this same copy sheet The rear edge is still moving with the initial image support surface, and the copy
In a reproduction apparatus wherein a sheet is adapted to extend between the rotating user roll nip and an initial image support surface, a leading edge portion of the copy sheet engages the rotating user roll nip; The initial image support surface and the rotary frame are arranged such that the speed at which the leading edge portion of the copy sheet is moved is faster than the speed at which the trailing edge portion of the copy sheet is moved when the trailing edge portion is moving with the initial image bearing surface. user·
a speed regulating device for moving the roll nip; and a vacuum guide surface that is concave and positioned between the initial image bearing surface and the rotating user roll nip and moves the copy sheet through the vacuum. for supporting by vacuum pressure the side of the copy sheet opposite to the side supporting the transferred unfused image in contact with the guide surface and guiding the copy sheet to the rotating user roll nip; a vacuum guide surface device; a vacuum reduction device for reducing the vacuum applied to the vacuum guide surface; and activating the vacuum reduction device when a leading edge portion of a copy sheet reaches the rotating user roll nip. and releasing the copy sheet supported along the concave vacuum guide surface to deactivate the vacuum reduction device when a trailing edge portion of the copy sheet leaves the initial image support surface. A copying apparatus comprising: a vacuum control device;