US3792925A

US3792925A - Preloading web cleaner

Info

Publication number: US3792925A
Application number: US00327404A
Authority: US
Inventors: G Milligan; J Toto
Original assignee: Sperry Rand Corp
Current assignee: Sperry Corp
Priority date: 1973-01-29
Filing date: 1973-01-29
Publication date: 1974-02-19
Anticipated expiration: 1991-02-19
Also published as: JPS49107542A; FR2328375A7; GB1427086A; NL7401130A; BR7307435D0; IT1006765B; DE2343134B2; DE2343134A1

Abstract

A xerographic copy machine is provided with an elongated web for wiping toner particles from the surface of a rotating xerographic drum. The web is supported by supply and take-up rolls carried on a pivotally mounted bracket. The bracket is spring biased to hold the web out of contact with the drum surface when the machine is idle. When the machine is turned on a electro-mechanical clutch is energized to rotate a latching mechanism including a cam and arm. The cam pivots the bracket to bring the web into wiping contact with the drum surface. The arm is rotated until it reaches a latching position where it operates a switch to deenergize the electro-mechanical clutch. A solenoid actuated latch holds the arm and cam in the rotated position until the machine power is turned off, at which time the latch releases the arm so that the arm and cam return to their initial position.

Description

United States Patent 1 Milligan et al.

[451 Feb. 19, 1974 PRELOADING WEB CLEANER [75] Inventors: Gordon L. Milligan, Norristown,

. Pa.; John A. Toto, Milford, Conn.

[73] Assignee: Sperry Rand Corporation, New

York I [22] Filed: Jan. 29, 1973 [21] Appl. No.: 327,404

[52] U.S.-Cl 355/15, 15/l.5, 15/256.52

[51] Int. Cl G03g 15/22 [58] Field of Search355/15; l5/1.5, 256.51, 256.52,

[56] References Cited UNITED STATES PATENTS 3,190,198 6/1965 Eichorn 355/15 3,625,605 12/1971 Schnall et a1. 355/15 3,712,734 1/1973 Jovanovic 355/15 3,717,409 2/1973 Hespenheide.. 355/15 3,728,016 4/1973 Harbour et al. 355/15 [5 7 ABSTRACT A xerographic copy machine is provided with an elongated web for wiping toner particles from the surface of a rotating xerographic drum. The web is supported.

by supply and take-up rolls carried'on a pivotally mounted bracket. The bracket is spring biased to hold the web out of contact with the drum surface when the machine is idle. When the machine is turned on a electro-mechanical clutch is energized to rotate a latching mechanism including a cam and arm. The cam pivots the bracket to bring the web into wiping contact with the drum surface. The arm is rotated until it reaches a latching position where it operates a switch to de-energize the electro-mechanical clutch. A solenoid actuated latch holds the arm and cam in the rotated position until the machine power is turned off, at which time the latch releases the arm so that the arm and cam return to their initial position.

10 Claims, 4 Drawing Figures PRELOADING WEB CLEANER BACKGROUND OF THE INVENTION In xerographic copy apparatus of the type employing a xerographic drum, it has been common practice to lay down a uniform charge on the drum, expose the charged drum surface to a light image of the document to be copied to thereby form an electrostatic image of the document on the drum surface, apply toner particles to the drum surface to thereby develop a visible image of the document on the drum surface, and transfer the image to a copy sheet. The image transfer operation does not transfer all of the toner particles from the drum surface to the copy sheet, so the remaining particles must be cleaned from the drum surface before it is ready for copying another document. The cleaning operation typically includes exposing the entire drum surface to light, applying a uniformcharge to the drum surface, the charge being of opposite polarity to the uniform charge initially placed on the drum, and, finally, wiping the drum surface with a brush or a weblike cleaning material to remove any toner particles still adhering to the drum surface. Cleaning brushes are quite expensive and have a very limited useful life so it is preferable to use cleaning Webs.

In prior art devices employing cleaning webs, it has been common practice to support the cleaning web so that it always remains in wiping contact with the drum surface, even when the machine is idling or off. However, it has been found that this results in a marking of the drum surface which is, typically, a layer of photoconductive insulating materialsuch as vitreous selenium. The marking of the drum by the cleaning web is more pronounced when the machine is in a high temperature environment and remains for an extended period of time with the web in wiping contact with a stationary drum.

Any marking of the drum is undesirable since it may result in spotting or streaking of copies made by the machine.

BRIEF SUMMARY OF THE INVENTION An object of the present invention is to provide an improvement in xerographic copy machines of the type employing a cleaning web to wipe the surface ofa xerographic drum, said improvement comprising means for moving said cleaning web into wiping contact with said drum when the copy machine is on, and means for retracting the cleaning web from the drum surface when the machine is off. I

An object of the present invention is to provide an improvement in xerographic machines of the type employing a cleaning web to wipe the surface of a xerographic drum, said improvement comprising first means for moving said cleaning web into wiping contact with said drum as driving power is applied to rotate said drum surface, second means for deactivating said first means and holding said cleaning web in wiping contact with said drum surface while said drum surface rotates, and third means for deactivating said second means and retracting said cleaning web from said drum surface the driving power rotating said drum surface is terminated.

A further object of the invention is to provide a pivotally mounted cleaning web support assembly pivotable between a first position where a cleeaning web supported by said assemblyis held out of contact with the surface of a rotating xerographic drum and a second position where the cleaning web is in wiping contact with the drum surface, a latching cam mechanism including a cam and an arm, means including a selectively energizeable clutch for rotating the latching cam mechanism whereby said cam pivots said cleaning web assembly from said first to said second position and said arm pivots to a latch position; a latch means including a solenoid operated latch lever for holding said arm in the latched position; switch means operated by said arm in said latch position for de-energizing said clutch. and bias means for pivoting said web assembly from said second to said first position when said solenoid is de-energized.

Other objects of the invention and its mode of operation will become evident upon consideration of the following description and the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 shows the position of various elements of the invention when the cleaning web is pivoted out of contact with the drum surface;

FIG. 2 shows the position of various elements of the invention when the cleaning web is pivoted into wiping contact with the drum surface;

FIG. 3 is a circuit diagram illustrating the electrical features of the invention; and,

FIG. 4 shows an alternate embodiment of the driving means.

DESCRIPTION OF A PREFERRED EMBODIMENT In order to better illustrate a preferred embodiment of the invention, FIG. 1 and 2 have been simplified to avoid the showing of structure not necessary to an understanding of the invention and its mode of operation. Thus, in FIG. 1 and 2 the reference numeral 10 represents a fixed support which may be the frame ofa xerographic copy machine or a fixed plate or other support rigidly attached, either directly or indirectly, to the machine frame.

A xerographic drum 12 is mounted for rotation about a shaft 14 supported by the fixed support 10. The drum 12 may be driven by means such as that shown in copending application Ser. No. 327,405 filed concurrently herewith. As explained in the co-pending application, the cylindrical surface of the drum comprises an insulating layer of photoconductive material responsive to light. The drum surface is first exposed to a corona discharge in order to place a unifrom charge on the drum surface. The drum surface is then exposed to the light image of a document to be copied to thereby selectively discharge certain portions of the drum surface and form thereon an electrostatic image of the document to be copied. Toner particles are then cascaded over the drum surface and these particles adhere to the areas of the drum that are still charged, thereby forming a visible image of the document to be copied. Subsequently, the drum is rotated through a transfer station where the visible image is transferred to a copy sheet.

As explained in the co-pending application, the transfer operation does not remove all of the toner particles from the drum. In order to clean the remaining particles from the drum the drum is rotated past a bank of lamps which illuminate the entire drum surface, past a further charging station which applies to the drum surface a charge opposite in polarity to the uniform charge initially laid down on the drum, and finally past a station where a cleaning web wipes the remaining toner particles from the drum surface.

FIG. 1 illustrates the position of various elements of the web cleaning station when no power is applied to rotate the drum 12. The web cleaning station'includes a web support means 16 for supporting an elongated cleaning web 17. The web support means includes two brackets 18, only one of whichis shown in FIG. 1.

The web support means further includes a web take up roll 22, a pressure roll 24, and a web supply roll 26. The pressure roll 24 and the supply roll 26 are supported between the brackets 18 by any conventional means which permits free rotation of the rolls. The take up roll 22 is driven by the shaft 20 and, as explained in the above mentioned co-pending application, the shaft 20 is driven by the same drive motor that drives the drum 12. As further explained in the co-pending application, a supply roll 26 containing a fresh or clean web roll thereon is mounted in the support means, drawn around periphery of the pressure roll 24, and attached to the take up spool 22. As long as the copy machine is on the drum 12 rotates in one direction and the web 18 is pulled in the opposite direction by the spool 22, the pressure roll 24 holding the web 18 in contact with the drum surface so as to wipe toner particles therefrom. Obviously, the width of the cleaning web 18 must be at least as wide as the width of the drum surface to be cleaned, and preferably the pressure roll 24 has a length at least as great as the width of the surface being cleaned so that the web is pressed with uniform pres sure against the drum surface along a line parallel to its axis of rotation.

A bias means such as a tension spring 28 is connected between one of the support brackets 18 and a fixed support 10. Because the entire web support means 16 is free to pivot about the shaft 20, the bias means 28 tends to rotate the support means in a clockwise direction about the shaft toward a first position whereat the web 17 is held out of contact with the surface of drum 12. A stop (not shown) may be provided to limit movement of the support means in response to the force exerted by the spring 28.

The web support means may be driven in a counterclockwise direction about the shaft 20 to a position whereat the cleaning web 17 is held in wiping contact with the surface of drum 12 of the pressure roll 24. This position is illustrated in FIG. 2 and represents the position of the various elements of the invention when the copy machine is ready for use or is in the process of making copies.

A shaft 30 is supported by a fixed support and is driven through conventional means by the same motor that drives the drum shaft 14 and the web take up shaft 20. The shaft 30 provides the mechanical input drive power to a conventional electro-mechanical spring clutch 32. A sprocket or toothed wheel 34 is freely mounted on the shaft 30 but is driven by the clutch 32 when the clutch solenoid 32a (FIG. 3) is energized. The sprocket 34 drives a chain 36 which is looped around a further sprocket 38 and a tension idler sprocket 40.

The sprocket 38 drives a shaft 42 supported by the fixed support 10. Affixed to the shaft 42 is a latching cam means including two earns 44, only one of which is shown, and a latch element or arm 46. The cams 44 have a caming surface 48. As the shaft 42 turns to rotate the latching cam means, the camming surfaces 48 engage the surfaces 50 on both brackets 48 and pivot the entire web support means in a counterclockwise direction about the shaft 20 so as to move the web support means from the first position shown in FIG. 1 t0 the second position shown in FIG. 2.

As the earns 44 pivot the web support means toward the second position, the latch element 46 moves towards a latching position illustrated in FIG. 2. A solenoid actuated latch means is provided for latching the latch element 46 in the position shown in FIG. 2. This latch means includes a latch lever 54 freely pivoted at one end on a fixed pivot 56. A solenoid 58 has an arma ture 60 connected by means of a tension spring 62 to a stud 64 on the latch lever 54. When the solenoid 58 is energized it pulls the lever 54 in a counterclockwise direction about the pivot 56 to move the lever into the latching position shown in FIG. 2. A bias means such as a torsion spring 66 is provided for biasing the lever 54 away from the latching position when the solenoid 58 is not energized.

The latch lever 54 is provided with a cut-out or notch 68 for capturing or latching the latch element 46. Furthermore, the lever 54 and/or the latch element 46 should be shaped in the

areas

70 and 72 to facilitate camming of the lever 54 upwardly as the latch element 46 moves into latching position. The reason for this will become evident from the subsequent description.

An electrical switch 74 is mounted on a fixed support and provided with a switch actuating arm 76. The actuating arm 76 is disposed in the path of movement of the latch element 46 and is adjusted so that contacts 7411 (FIG. 3) are actuated when the latch element 46 has pivoted sufficiently far in the clockwise direction to latch within the recess 68 in the latch lever 54.

FIG. 3 is a circuit diagram illustrating the electrical circuit associated with the present invention. Means such as a power source V is provided for selectively and concurrently energizing solenoid 58, the drive motor M and'the clutch coil 32a when switch contacts 80 are closed. The contacts 80 are normally open but are closed when the copy machine is turned on. The motor M comprises the drive means which provides the mechanical driving power for rotating the drum shaft 14, the web take up roll shaft 20, and the electromechanical clutch shaft 30. As long as the copy machine is not ready for operation, that is, as long as switch contacts 80 are open, the elements of the apparatus are in the position shown in FIG. 1.

When the switch contacts 80 are closed, the motor M, the solenoid 58, and the clutch solenoid 32a are all energized. When the motor is energized it begins driving the drum l2 and the

shafts

20 and 30. As the shaft 20 is rotated the take up spool 22 rotates and begins moving the cleaning web 17.

When the solenoid 58 is energized its armature 60 is pulled downwardly thus moving latch lever 54 from the position shown in FIG. 1 to the position shown in FIG. 2. At the same time, energization of clutch solenoid 32a couples driving power from shaft 30 to the sprocket 34 and the sprocket begins driving the chain 36. The chain 36, acting through sprocket 38, rotates shaft 42 thus pivoting cams 44 and latch element 46 in a clockwise direction. As cams 44 pivot, they engage the surfaces 50 and pivot the web support means 16 from the position shown in FIG. 1 to the position shown in FIG. 2. During this interval the surface 72 of latch element 46 engages the surface 70 of latch lever 54 and the lever 54 is pivoted upwardly as the latch element continues its clockwise rotation. This upward movement of the latch lever 54 is permitted by the tension spring 62 even though the solenoid 58 is energized at this time.

As the latch element 46 continues its clockwise rotation, it eventually reaches a point opposite the cutout 68 in the latch lever 54 and the spring 62 pulls the latch lever downwardly to latch the latch element 46 in its latching position as illustratedin FIG.v 2. When the latch element 46 has reached the latching position, it operates the arm 76 associated with the switch 74 to thus open the contacts 74a in FIG. 3. This de-energizes the solenoid 32a of the clutch 32 so that driving power is no longer applied to the gear 34. At this time all elements are in the position shown in FIG. 2 and the elements remain in this position as long as the machine is in operation.

When it is desired to stop the machine operation, the switch contacts 80 are opened to de-energize the motor M and the solenoid 58. The drum 12 and the web take up roll 22 stop rotation as does the clutch shaft 30. When the solenoid 58 is de-energized the bias means 66 pivots the latch lever upwardly thus releasing the latch element 46. The tension spring 28 acts on the bracket 18 to rotate the entire web support means 16 in the clockwise direction and as this rotation takes place the bracket surface 50 engages cam surface 48 to thus rotate earns 44 and latch element 46 toward the position shown in FIG. 1. The device is then ready for, a new cycle of operation when the copy machine is again readied for use by closing the switch contacts 80.

It should be noted that the latch element 46 and/or the cams 44 should be adjustably affixed to the shaft 42 to permit relative angular adjustment between the cams and the latch element. The adjustment should be such that when the latch element 46 is latched in its latching position as illustrated in FIG. 2, the cams 44 act against the web support means 16 with a force such that the pressure roller 24 presses the web 17 against the drum surface with a desired force. The adjustment should also be such that when the latch element 46 is in the latching position shown in FIG. 2, there is a slight clearance between cam stop 82 and the projection 50 on the bracket 18. This allows the latch element 46 to move slightly beyond the latching position before it operates the switch 74. The cam stop 82 is provided only to limit the clockwise pivotal movement of cam 44 and latch element 46 beyond the position where the latch element should operate the switch 74.

While a preferred embodiment of the invention has been described in detail, it will be obvious that various substitutions and modifications may be made in the preferred embodiment without departing from the spirit and scope of the invention as defined by the appended claims. For example, the chain or closed loop drive means need not encircle the sprocket 38 but may instead merely be pressed into engagement with the sprocket, as illustrated in FIG. 4.

The embodiments of the invention in which an exclusive property or privilege is claimed or defined as follows:

1. In a xerographic copier of the type wherein an elongated cleaning web engages in wiping contact with the surface of a rotating xerographic drum, the improvement comprising:

a support means for supporting the cleaning web;

a pivot on which said support means is mounted for pivotal movement between a first position whereat the cleaning web is held out of contact with the surface of said drum and a second position whereat the cleaning web is in wiping contact with the surface of said drum;

a selectively energizable clutch;

latching cam means including a cam means and a latch element, said cam means being positioned adjacent said support means;

means for energizing said clutch;

means responsive to said clutch for driving said latching cam means whereby said cam means pivots said support means from said first position to said second position, and said latch element is moved from an initial position to a latching position;

latch means at said latching position for latching said latch element; and,

switch means operated by said latch element when at said latching position for de-energizing said clutch.

2. The improvement as claimed in claim 1 wherein said latch means includes a latch lever and a solenoid for moving said latch lever into position to latch said latch element at said latching position.

3. The improvement as claimed in claim 2 and further comprising:

means for selectively energizing said solenoid to move said latch lever into position to latch said latch element;

first bias means tending to move said latch lever away from the position where it latches said latch element; and

second bias means for driving said support means toward said first position when said solenoid is deenergized.

4. The improvement as claimed in claim 3 wherein the means for selectively energizing said solenoid and for energizing said clutch comprises means for energizing said solenoid and clutch any time said drum rotates.

5. The improvement as claimed in claim 4 wherein said solenoid includes an armature, and a tension spring connecting said armature to said latch lever.

6. The improvement as claimed in claim 3 wherein said latch cam means is mounted on a shaft for pivotal movement.

7. The improvement as claimed in claim 6 wherein said support means engages said cam means and pivots said latch cam means when said support means is driven by said second bias means.

8. In a xerographic copier, the combination comprising:

a rotatable xerographic drum;

web support means mounted for pivotal movement between a first position whereat a cleaning web supported by said support means is held out of contact with said drum, and a second position whereat the web engages said drum in wiping contact;

a selectively energizable clutch means;

drive means for driving said drum and said web, and

said clutch means;

latchable cam means driven by said clutch means for pivoting said web support means from said first to said second position, said latchable cam means including a latch element which moves to a latching position as said web support means is pivoted to switch means operated by said latch element when it is in said latching position for de-energizing said clutch means and,

bias means normally biasing said support means toward said first position and said latch element away from said latching position when said solenoid is not energized.

9. The combination as claimed in claim 8 wherein said latchable cam means includes two cams, said cams and said latch element being mounted on a shaft for pivotal movement, and means including a closed loop drive element driven by said clutch'm'e'ans for imparting rotational movement to said shaft, said clutch means including an electro'mechanical clutch.

10. The combination as claimed in claim 9 wherein said latch means includes,

a latch lever, V

a tension spring connecting said lever to the armature of said solenoid, and,

a further bias means tending to move said latch lever to free said latch element when'said solenoid is not energized.

Claims

1. In a xerographic copier of the type wherein an elongated cleaning web engages in wiping contact with the surface of a rotating xerographic drum, the improvement comprising: a support means for supporting the cleaning web; a pivot on which said support means is mounted for pivotal movement between a first position whereat the cleaning web is held out of contact with the surface of said drum and a second position whereat the cleaning web is in wiping contact with the surface of said drum; a selectively energizable clutch; latching cam means including a cam means and a latch element, said cam means being positioned adjacent said support means; means for energizing said clutch; means responsive to said clutch for driving said latching cam means whereby said cam means pivots said support means from said first position to said second position, and said latch element is moved from an initial position to a latching position; latch means at said latching position for latching said latch element; and, switch means operated by said latch element when at said latching position for de-energizing said clutch.

3. The improvement as claimed in claim 2 and further comprising: means for selectively energizing said solenoid to move said latch lever into position to latch said latch element; first bias means tending to move said latch lever away from the position where it latches said latch element; and second bias means for driving said support means toward said first position when said solenoid Is deenergized.

8. In a xerographic copier, the combination comprising: a rotatable xerographic drum; web support means mounted for pivotal movement between a first position whereat a cleaning web supported by said support means is held out of contact with said drum, and a second position whereat the web engages said drum in wiping contact; a selectively energizable clutch means; drive means for driving said drum and said web, and said clutch means; latchable cam means driven by said clutch means for pivoting said web support means from said first to said second position, said latchable cam means including a latch element which moves to a latching position as said web support means is pivoted to said second position; a solenoid and means actuated by said solenoid for latching said latch element at said latching position; means selectively and concurrently energizing said drive means, said clutch means, and said solenoid to thereby drive said drum and said web, drive said latchable cam means to pivot said support means to said second position, actuating said latch means to latch said latch element; switch means operated by said latch element when it is in said latching position for de-energizing said clutch means and, bias means normally biasing said support means toward said first position and said latch element away from said latching position when said solenoid is not energized.

9. The combination as claimed in claim 8 wherein said latchable cam means includes two cams, said cams and said latch element being mounted on a shaft for pivotal movement, and means including a closed loop drive element driven by said clutch means for imparting rotational movement to said shaft, said clutch means including an electro-mechanical clutch.

10. The combination as claimed in claim 9 wherein said latch means includes, a latch lever, a tension spring connecting said lever to the armature of said solenoid, and, a further bias means tending to move said latch lever to free said latch element when said solenoid is not energized.