US3820888A - Mistrack interlock for selenium belt - Google Patents

Abstract

A switching assembly for an endless belt assembly of an electrostatographic machine is disclosed including two switches and a switch lever disposed therebetween is provided near the photoconductive belt assembly with the switch lever being in contact with a sensing ring of a tracking assembly for the endless belt assembly. The switching lever moves response to variations in positioning of the sensing arm and will de-activate the operational mode of the machine through the switching assembly should the tracking of the belt become irregular and uncontrollable. Additionally, the switching assembly may be opened by an adjusting means to prevent the unintentional startup of the belt assembly during replacement of a belt.

Description

United States Patent [19 Jordon 1 11] 3,820,888 June 28, 1974 MISTRACK INTERLOCK FOR SELENIUM [54] 3,646,866 3/1972 Baltazzi et al. 355/16 X BELT 3,726,588 4/1973 Moser 355/3 [75] Inventor: William E. Jordon, Penfield, N.Y. Examiner Robert R Greinel. [73] Assignee: Xerox Corporation, Stamford,

Conn. [57] ABSTRACT [22] Filed; 1, 1972 A switching assembly for an endless belt assembly of an electrostatographic machine is disclosed including PP 3119344 two switches and a switch lever disposed therebetween is provided near the photoconductive belt assembly 52 us. (:1 355/3 R, 355/16, 226/43, with the Switch lever being ih Contact with a Sensing 226/48, 226/2], 226/23, 198/202 ring of a tracking assembly for the endless belt assem- [51] Int CL" G03g 5 B651l 25/06 /26 bly. The switching lever moves response to variations 58] Field of Search 355/3, 16; 226/43, 48, in Positioning of the Sensing am and will tie-activate 2 2 2 2 99; 9 2 the operational mode of the machine through the switching assembly should the tracking of the belt be- [56] References Cited come irregular and uncontrollable. Additionally, the UNITED STATES PATENTS switching assembly may be opened by an adjusting means to prevent the unintentional start-up of the belt ginger}. assembly during replacement f a be 3:5l3:966 5/1970 561x151...........I...:I...:..I .198/202 1 Claim, 3 Drawing Figures /as v O 13a 0 PATENTEDJUNZB m4 sum 10F 3 206853 FIG 1 MISTRACK INTERLOCK FOR SELENIUM BELT BACKGROUND OF THE INVENTION This invention relates to electrostatography, and more particularly to improvements in a belt tracking system for an endless photoconductor belt whereby uncontrolled tracking of the belt is senses and the machine placed in an inoperational mode. The tracking system in accordance with thepresent invention is particularly adapted for use with selenium belts in auto matic copies/reproducers which are constructed for high speed operation and capable of having their timing sequence varied thereby permitting variable speeds of output.

In' the practice of xerography as described in US. Pat. No. 2,297,69l to Chester F. Carlson, a xerographic surface comprising a layer of photoconductive insulating material affixed to a conductive backing is used to support electrostatic images. In the usual method of carrying out the process,'the xerographic plate is electrostatically charged uniformly over its surface and then exposed to a light pattern of the image being reproduced to thereby discharge the charge in the areas where light strikes the layer. The undischarged areas of the layer thus form an electrostatic charge pattern in conformity with the configuration of the original light pattern.

The latent electrostatic image may then be developed by contacting it with a finely divided electrostatically attractable material, such as a resinous powder. The powder is held in the image areas by the electrostatic fields on the layer. Where the field is greatest, the greatest amount of material is deposited; and where the field is least, little or no material is deposited. Thus, a powder image is produced in conformity with the light image of the copy being reproduced. The powder is subsequently transferred to a sheet of paper or other surface and suitably fixed to thereby form a permanent print.

The latest machine concept for copiers utilizes high speed flash exposure of a document and the arrangement of a moving photoconductor material in the form of an endless belt including the continuously charging thereof together with provisions for solid coverage.

hotoconductor belts are very delicate, are easily damaged, and the movement thereof through processing stations in a reproduction machine must be accomplished with high precision and with as little irregular movement as possible. Should the tracking of the photoconductive belt become irregular and uncorrectable, the machine must be placed in an inoperative mode as quickly as possible to prevent irreparable damage to the photoconductive belt as well as the machine.

OBJECTS OF THE INVENTION An object of the present invention is to provide a position detecting assembly for a photoconductor belt of an electrostatographic machine.

Another object of the present invention is to provide a means for placing an electrostatographic machine in an inoperative mode should the tracking of a photoconductive belt positioned on a belt assembly become irby a switching assembly including two switches and a switch lever disposed therebetween is provided near the photoconductive belt assembly with the switch lever being in contact with a sensing ring of the tracking assembly for the endless belt'assembly of an electrostatographic machine. The switching lever moves in response to variations in positioning of the sensing arm and will deactivate the operational mode of the machine through the switching assembly should the tracking of the belt become irregular and uncontrollable.

DESCRIPTION OF THE DRAWINGS A better understanding of the present invention as well as other objects and further features thereof will become apparent upon consideration of the following detailed disclosure thereof, especially when taken with the accompanying drawings, wherein like numerals designate like parts throughout, and wherein.

FIG. 1 is a schematic sectional view of an electrostatic reproduction machine embodying the principles of the invention.

FIG. 2 is an isometric view of a portion of the belt assembly as seen from the other side of the machine of FIG. 1; and

FIG. 3 is a top view of the switching assembly associated with the tracking assembly.

For a general understanding of the illustrated copier reproduction machine in which the invention may be incorporated, reference is had to FIG. 1 in which the various system components for the machine are schematically illustrated. A document to be copied is placed upon a transparent support platen P fixedly arranged in an illumination assembly, generally indicated by the reference numeral 10, positioned at the left of the machine. Light rays from an illumination system areflashed upon the documents to produce image rays corresponding to the informational areas. The image rays are projected by means of an optical system onto the photoconductive surface of a xerographic plate in the form of a flexible photconductive belt 12 arranged on a belt assembly, generally indicated by the reference numeral 14.

The belt is comprised of a photoconductive layer of selenium which is the light receiving surface and imaging medium for the apparatus formed on a conductive backing. The surface of the photoconductive belt is made photosensitive by a previous step of uniformly charging the same by means of a corona generating device or corotron T3.

The belt is journaled for continuous movement upon three rollers 20, 21 and 22' positioned with their axes in parallel. The photoconductive belt assembly 14 is slidably mounted upon two support shafts 23 and 24 with the roller 22 rotatably supported on the shaft 23 which is secured to the frame of the apparatus and is rotatably driven by a suitable motor drive assembly (not shown) in the direction of the arrow as a constant rate. During exposure of the belt 12, the portion ex-,

posed is that portion of the belt running between rollers .20 and 211. During movement of the belt 12, the reflected light of the original document positioned on the platen is flashed on the surface of the belt to produce an electrostatic latent image thereon at exposure station A.

As the belt surface continues its movement, the electrostatic image is passed through a developing station B which there is positioned a developer assembly, generally indicated by the reference numeral 15, and which effects development of the electrostatic image by means of multiple magnetic brushes 16 as the image moves through the development zone.

The developed electrostatic image is transported by the belt to a transfer station C whereat a sheet of copy paper is moved between a transfer roller (of transport roller assembly 29) and the belt at a speed in synchronism with the moving belt in order to accomplish transfer of the developed image by an electrical bias on the transfer roller. There is provided at this station a sheet transport mechanism, generally indicated at 17, adapted to transport sheets of paper from a paper handling mechanism, generally indicated by the reference numeral 18, to the developed image on the belt at the station C.

After the sheet is stripped from the belt 12, it is conveyed into a fuser assembly, generally indicated by 19, wherein the developed and transferred xerographic powder image on the sheet material is permanently fixed thereto. After fusing, the finished copy is discharged fromthe apparatus at a suitable point for collection externally of the apparatus. The toner particles remaining as residue on the developed image, background particles and those particles otherwise not transferred are carried by the belt 12 to a clearing app aratus 26 positioned on a course of the belt between rollers 20 and 22 adjacent to charge device 25.

Further details regarding the structure of the belt assembly l4 and its relationship with the machine and support therefor may be found in the copending application Ser. No. 102,312, assigned to the same assignee.

' upper roller 20 and the tracking roller 21. The upper roller 20 is rotatably supported on a hollow shaft 32 journaled for rotation in bearings disposed in side plates (not shown) such as described in corresponding application Ser. No. 102,311 to David Roth Stokes et al., entitled BELT TRACKING SYSTEM, assigned to the same assignee. The tracking roller 21 is secured to a shaft 34 journaled for rotation in bearings (not shown) secured to the ends of parallel legs 36 and 38 of a yoke member 40.

At the mid point of the yoke member 40 and extending in an opposite direction relative to the legs 36 and 38, there is provided a shaft, generally indicated as 42, to support the yoke member 40 for limited rotational movement about the axis of the shaft 42 and to permit slight retraction. The shaft 42 is positioned within a cylinder 44 of relatively large diameter disposed within spaced bearings 46 mounted to a frame 48 and having a coaxial reduced portion 50 secured to the lower portion of the cylinder 44 and disposed within a suitable opening, formed in the blight portion of the yoke member 40. A relatively heavy coil spring encircles the portion 50 between the yoke member 40 and the lower surface of the lower bearing 46. The spring imparts a continuous downward force upon the yoke and consequently the roller 21, when the belt 12 is mounted on its supporting rollers thereby placing belt 12 under slight tension during operation. The structural connection between the yoke member and the portion 50 is slightly loose to allow for limited play between these parts to correct for circumferential variations in manufactured belts.

The upper portion of the cylinder 44 is formed with a tubular sleeve 52 axially aligned therewith. Suitable openings are formed in the sleeve 52 in diametrically opposed positions for supporting a pin 54 which is pivotally connected to one end of a toggle link 56 to the end of a cylinder 44. The link 56 is pivotally connected at the other end to one end of another toggle link 58 having its opposite end pivotally connected to the frame structure 48. It will be apparent that the toggle links 56 and 58 and their respective connections form a toggle assembly which when actuated into alignment will cause the cylinder 44 to move downwardly within the bearing 46 and when actuated into a buckled condition will cause the cylinder 44 to be retracted upwardly.

Actuation of the toggle assembly is produced by a drive link 60 which is pivotally connected at one end to the pivot connection between toggle links 56 and 58 extending transverse of the belt assembly 30 through an outer wall 62 and terminating in a pivotal handle 64 which moves drive link 60 axially to actuate toggle links 56 and 58. In order to remove or to replace a belt photoconductive 12, the handle 64 is suitably moved to cause buckling of the toggle links 56 and 58 which action draws the cylinder 42 upwardly within the bearings 46 to retract the roller 21. Sufficient slack is thereby provided to the belt 12 to permit an operator to move a belt relatively easily over the rollers 20, 21 and 22. After placing a belt over the rollers the handle 64 is moved in an oppostie direction to place the toggle links 56 and 58 in an aligned condition thereby forcing the roller 21 against the belt 12 and locking the roller 21 in such position.

A flat sensing ring is mounted for rotation about a bearing 72disposed on a support plate 74 having a diameter smaller than roller 20 and provided with a curved arm 76. The sensing ring 70 is preferably made of wear-resistant plastic material which will not become damaged when placed in contact with the relatively sharp edge of the photoconductive belt 12, and which will not cause fraying or other damage to the coacting edge of the belt 12. The support plate 74 is provided with a central opening 78 which allows the assembled structure comprising ring 70, bearing 72 and the plate 74 to accommodate and avoid the adjacent end of the shaft 32 and allow the ring 70 to engage the edge of the belt 12.

The curved arm 76 of the support plate 74 is provided with an orifice which fixedly receives the upper portion of an inclined shaft 80 mounted for rotation about its longitudinal axis within a fixed cylindrical casting 82 mounted by a spaced bracket 84 to the frame structure 8, such as by screws (not shown). Suitable bearings (not shown) are utilized within the casting 82 between the same and the shaft 80 in order to facilitate the rotating relationship therebetween. The lower end of the shaft 80 is formed with a reduced portion 86 to which is attached an arm 88 extending perpendicularly relative to the axis of the shaft 80 to swing in either direction upon corresponding rotational movement of the shaft 80.

The arm 88 is pivotally connected to a link member 90 including an externally threaded portion 92. Another link member 94 including an externally threaded portion 96 is secured to an arm 97 of ear 98 formed on the upper portion of the yoke member 40. A cylindrically shaped sleeve 100 including a sprocket 102 threadably engages the threaded portions 92 and 96 of each of the link members 90 and 94, respectively, thereby providing a turnbuckle assembly, generally indicated as 99, for altering the distance between the axis of the roller 21 and the axis of the shaft 80 by rotation of the sleeve 100, as more fully hereinafter described.

A spring 101 is provided over the threaded portion 96 of the member 94 between the sleeve 100 and the end of link member 94 to prevent the unintentional rotation of the sleeve 100, such as by vibrations. A support assembly 104 is mounted to the frame (not shown) and receives for rotation, a shaft 106 disposed within an opening formed in upturned legs 108 of the support assembly 104. A dial 110 is fixedly secured to an end of the shaft 106 extending outwardly from the frame. A sprocket 112 is fixedly secured to a mid portion of the shaft 106 between the legs 108 thereof.

A shoulder bearing assembly 114 is positioned over a shaft 116 mounted on the support assembly 104. An endless chain 118 is positioned about the sprocket 112 disposed on the shaft 106, the shouldered bearing assembly 114, and about the sprocket 102 formed on the sleeve 100. A tubular member is provided between the shoulder bearing means 114 and the sprocket 102 to guide the chain 118 between the shouldered bearing assembly114 and the sprocket 102. It will be readily appreciated that rotation of the dial 110 in either direction will cause the sleeve 100 to rotate, thereby varying the distance between the center line of the arm 88 and Minor variations of the tracking of a photoconductive belt 12 about the belt assembly 30 is corrected in the manner described in the aforementioned application Ser. No. 102,31 1. It will be appreciated that a replacement belt may be formed with a minor variation in the circumference thereof as compared with the photoconductive belt being replaced. Such a variation in circumference would result in mistracking and require excessive trial and error adjustment but may be readily compensated for by adjustment of the turnbuckle assembly 19 as disclosed in copending application of Jordan et a]. entitled TRACKING ASSEMBLY FOR AN ENDLESS BELT ELECTROSTATO- GRAPHIC MACHINE.

Referring now to E10. 3, there is illustrated an interlock adjustment assembly, generally indicated as 120 for providing, inter alia, a means for placing the machine in an inoperative mode should the tracking of the photoconductive belt 12 become irregular and vary beyond predetermined limits. The interlock adjustment assembly 120 includes a base member 122, a slide 124, switches 126 and 128, a sensing lever 130 and an adjusting cable 132. The base member 122 including slide receiving slots 134, is suitably mounted to the frame 48 of the machine, such as by bolts 136. The slide 124 is transversely disposed within the slots 134 of the base member 122 and is provided with switches 126 and 128 including inwardly extending switching arms 136 and 138 mechanically coupled to the respective movable contacts thereof. The sensing lever 130 is pivotally mounted to base member 122 about a shaft assembly 140 and is spring loaded in a clockwise direction by spring 142 affixed to the base member 122 on an extension area 144 thereof and to a shaft 146 disposed on the sensing lever 130. A

The switches 126 and 128 are closed and connected in series for marginal operation. Alternatively, switches 126 and 128 may be connected in parallel relationship. Accordingly, the coursing of the electrostatographic belt 12 is sensed by the arm'70 which in turn causes the sensing lever 130 to pivot in either direction about the shaft 140. Should the coursing become irregular, and not compensatable by the tracking assembly, the sensing lever eventually contacts the arm 136 or the arm 138 of switch 126 or 128 respectively which results in the interruption of (or alternatively, the generation of) a signal that is detected by the logic module of the control apparatus (not shown) to immediately effect the shut down of the electrostatographic apparatus. Upon properly retracking of the photoconductive belt 12 on the rollers, the sensing lever 130 is repositioned between the arms 136 and 138 of the switches 136 and 128 respectively, thereby closing the series circuit and permitting start-up of the machine.

While the invention has been described in connection with a preferred embodiment thereof, it will be understood that many modifications will be apparent to those of ordinary skill in the art; and-thatthis application is intended to cover any adaptations thereof. Therefore, it is manifestly intended that this invention I be only limited by the claims and the equivalents thereof.

What is claimed:

1. An improved reproduction machine comprising:

a. a plurality of rollers for supporting and guiding a flexible belt;

b. a flexible belt positioned on said rollers, said belt having a photoconductivearea thereon;

0. means including a sensing ring for sensing the position of one edge of said belt as the latter is moving over one of said rollers to detect any irregular coursing of said belt and for correcting said irregular coursing at another of said rollers; and

(1. means including a lever and two switches for placing said machine in an inoperative mode when said edge moves beyond a predetermined limit, said lever being mounted so as to pivot about an axis through the central portion thereof, one end of said lever being in contact with said sensing ring, and the other end of said lever being disposed between said switches and adapted to contact one of said switches when said lever is pivoted about said axis.

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Claims (1)

1. An improved reproduction machine comprising: a. a plurality of rollers for supporting and guiding a flexible belt; b. a flexible belt positioned on said rollers, said belt having a photoconductive area thereon; c. means including a sensing ring for sensing the position of one edge of said belt as the latter is moving over one of said rollers to detect any irregular coursing of said belt and for correcting said irregular coursing at another of said rollers; and d. means including a lever and two switches for placing said machine in an inoperative mode when said edge moves beyOnd a predetermined limit, said lever being mounted so as to pivot about an axis through the central portion thereof, one end of said lever being in contact with said sensing ring, and the other end of said lever being disposed between said switches and adapted to contact one of said switches when said lever is pivoted about said axis.

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