IL41129A - Electrostatic reproduction machine - Google Patents

Abstract

A pre-development exposure assembly is provided within an electrostatic reproduction machine transverse to the photoconductive surface thereof to selectively expose side portions of the photoconductive surface in response to a signal generated by a switch associated with the paper supply assembly responsive to paper size therein. [US3809472A]

Description

Electrostatic reproduction machine XEROX CORPORATION 59066 This relates to and particularly to an electrostatic reproduction the practice of xerography as described in Patent to Chester a xerographic surface comprising a layer of photoconductive insulating material affixed to a conductive backing is used to support electrostatic In the usual method of carrying out 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 The undischarged areas of the layer form an electrostatic charge patter conormity with the configuration of the light The latent electrostatic may then be developed by contacting it a finely divided electrostatically attractable such as a resinous The powder is held in the image areas by the electrostatic fields on the Where the field is the greatest amount of material is and where field is little or no material is Thus a in conformity the light image of the copy being The powder is subsequently transferred to a sheet of paper or other surface suitably afixed to thereby form a permanent The latest concept for utilizes exposure of a document and the arrangement of moving material in the form of an endless the photoconductive surface of such a machine is continuously order to effectively develop tine latent produced such machine with provision solid area a developing system is employed which supplies tone particles in relatively production rates are more readily achievable by passing the rectangular image receiving member sideways through the transfer and fixing stations as distinguished from transit as performed by most prior art means using a rectangular line copy original with the lines parallel to shorter dimension of the the machine would normally be arranged to operate so in the developed image would be parallel to the direction of rotation of the photoconductive Such machines are also being provided with image reducing Exposure of a translucent document on a platen to be reproduced in reduced results in there ore planes on opposed margins of the photoconductive which margins are on opposite sides of the of the photoconductive assuming alignment of the document so as to produce an image on a central portion of the width of the photoconductive as distinguished rom edge alignment on the Such after passage through a developing station designed for the development of solid would contain a high concentration of toner in developed solid are not in response to exposure of such area to light of an mage to be the photoconductive belt lis passed through a transfer station in contact with an image receiving member of a length measured across the width of the photoconductive belt equal to that of the original the top and bottom of the receiving is o a length corresponding to the of the reduced or particles will through transfer portion adhering the remaining portion of th toner is a cleanin assembly for prior to charging of the Such a would require excessive cleaning burden toner particle handling assemblies and result in excessive toner Paten a xerographic reproduction machine a first discharge adapted to illuminate the entire surface of the photoconductor after to assure complete discharge the background areas of image transfer of the to the copy paten also discloses a second lamp completely discharging the photoconductive cleaning thereof to remove any electrostatic charge which remain thereon before recharging the sur She patent does not discharging selective or strips on the photoconductive surface to prevent developmen thereof beyond the image area or outside of the corresponding to the size of copy paper utilised in the The present invention which prevents unwanted developmen of side portions of the is not taught or suggested by the Patent discloses a for discharging portions of a photoconductor when a copy machine operated reduction to prevent formation of black o developed borders on copy paper when the reduced linage is smaller than the size of receiver member or copy She patent is concerned solely the developmen problems encountered in reduction As it discloses a with image reduction lens to discharge portions of photoreceptor The present invention particularly points out the relationship between the photoreceptor discharge device and the size of the receiver member or copy paper to prevent development of the photoreceptive surface those areas of the photoreceptive surface that would extend beyond the edges of the receiver Patent concerned solel with the discharge of th photoconductive surface lying withi the area covered by the copy paper but without the reduced image Patent discloses a photographic machine with film film transport and film developer To eradicate undesirable edge a masking having single and multiple masking is Each masking area a and platen means to maintain film In the film in following exposed again along the periphery of the image by light from a lamp which strikes the film around and outside the edges of the believed evident from the above discussion of each of these newly cited they not disclose or tailoring the or configuration of area discharged in response to the size of the receiving According to the present Invention there is provided an electrostatic reproduction machine having a movable means to form an electrostatic latent image on the photoconductive developing means positioned at a development zone to develop said electrostatic latent and transfer means positioned at a transfer zone to effect a transfer of the developed electrostatic image onto an image receiving the machine including a discharge device adapted when activated substantially to discharge a charged area on at least one margin of said photoconductive surface prior to development of said latent and means operatively associated with said discharge device for controlling the activation of said discharge device in response to the size of said image receiving Preferably the discharge device is positioned substantially to discharge said charged area on said margin or margins after exposure of said photoconductive In a preferred said means for controlling the activation of said discharge device comprises control means coupled to said discharge device for activating said discharge device in response to a predetermined electrical and signal generating means responsive to the size of said image receiving member for generating said predetermined electrical signal when said image receiving member is of a predetermined said signal generating means being coupled to said control One electrostatic reproduction machine in which such an arrangement may be employed is one which includes an image receiving member supply and said signal generating means includes switch means positioned at said supply station for sensing a predetermined dimension of an image receiving member aosommodated at said supply said switch means developing said predetermined electrical signal when said predetermined dimension is less than a predetermined it is preferred that the discharge device should discharge charged areas on two opposed margins of the i photoconductive A convenient form of discharge device in an electrostatic reproduction machine in accordance with the invention is disposed adjacent to the photoconductive surface and includes a housing having a pair of slits adjacent ends of said housing and an illumination device positioned within said housing adjacent said said illumination device being activated by said control means for discharging charged areas on two opposed margins of said photoconductive A preferred form of discharge device in an electrostatic reproduction machine in accordance with the invention is disposed adjacent to the photoconductive surface and includes a housing having two pairs of the slits of each pair being adjacent opposed ends of said and a pair of illumination devices each positioned within said housing adjacent a different pair of said the reproduction machine further comprising a pair of said control means and an associated pair of said signal generating each of said illumination devices being activated by an associated one of said pair of control means for discharging charged areas on two opposed margins of said photoconductive the margins discharged by one of said illuminatio devices being of width different from the width of the margins discharged by the other of said illumination An electrostatic reproduction machine in accordance with the invention will now be described by way of example with reference to the accompanying drawings in Figure 1 is a schematic sectional view of an electrostatic reproduction in accordance with the inventio Figure 2 is a plan view of the exposure of the Figure Figure 3 is a the daveiopmeat assembly taken lines of of Figure For a general understanding of the illustrated machine in accordance with reference is to Figure 1 in which the various for the machine A document to be is placed upon a support platen fixedly arranged in an illumination generally indicated b the reference numeral positioned at the left end of the Light rays from an illuminatio system are the document to produce rays corresponding to th informational The rays are projected by of an optical system onto the photosensitive of a xerographic plate i the of a flexible photoconductive belt 12 arranged on a belt generally indicated by the reference belt 12 comprises a photoconductive layer of selenium which is the light receiving surface and stadium for the on conductive surface of the belt is photosensitive by a previous ste uniformly charging the same b means of a coron generating device or corotron The belt is journaled for continuous upon three rollers 21 and 22 positioned with in photoconductive y is mounted upon two support and 24 with the roller 22 supported on the shaft 23 which is secured frame of the apparatus and is rotatabl driven by a suitable exposed of belt running between rollers 20 and During such of the belt the reflected light of such original document positioned on the platen is flashed on the surface of the bel to produce an electrostatic latent image thereon at exposure station the belt surface continues its electrostatic passes through a developing B in which there is positioned a developer assembl generally indicated by reference numeral and whic of the electrostatic by of brushes 16 as the sieves through the The developed electrostatic image is by the belt to transfer station C whereat a sheet o cop paper is between a transfer roller and the belt at a speed in synchronism with the in order accomplish transfer of the developed image solel by an electrical on the transfer There is provided at this station a sheet transport mechanism generally indicated at 17 adapte to transport sheets of paper from a paper handling generally indicated by reference numeral 18 a paper suppl elevator to the developed on the belt at station After the sheet is stripped the bel it conveyed into a generally indicated by the reference numeral wherein the developed and xerographic image the sheet material permanently a After the finished copy is discharged from the apparatus at a suitable point for collection externall of the details the to which reader The exposure of the ejBbodiznent of the apparatus of the present Invention shovm in the generally indicated as is positioned within the lower portion of the reproduction machine between the exposure station A and the developing station as illustrated in Figure Referring now to Figures 2 and the assembly 30 is comprised of a molded housing a base 34 and discharge such as fluorescent lamps 36 and 38 activated by a conventional energising means The housing 32 formed with a top wall side walls 42 and and end walls 46 and Within the housing there provided an intermediate wall 50 forming chambers 52 and 54 in which lamps 36 and are The top wall 40 of the housing 32 formed with pairs of cooperating slits 56 and 58 which permit the passage of actinic radiation through from fluorescent lamps and The exposure assembly 30 provided with a bracket generally indicated as for mounting the assembly 30 within the electrostatic Each of the fluorescent lamps 36 and 38 may be provided with a control such as described in Patent Specification to which the reader each of which control circuits being energized a signal from a switch provided on the paper supply elevator as described la Patent Specification and in the specification of our Patent to both which specifications the is also operation of a hereinabove the pnotoconductive belt is continuously for by corona charging a such as disclosed in to If in one for the of paper i the assembly corresponds to that of the document to neither of the control circuits associated with the respective fluorescent lamps will be Should a signal be developed by a switch disposed the supply assembly sensing that the supply paper is of smaller dimension than the designed dimension of the supply a corresponding control system is energised thereby illuminating the respective fluorescent to expose continuously the opposed margins cylindrical planes at the roller of the photocondnctive of width determined by the width of the pair of through which the light It will be appreciated that in the absence of such develope particles would adhere to those being no image receiving surface of sufficient dimension at the transfer station some of the toner particles would attach to the transfer roller with the subsequent requirement of transfer roller while the remaining portion of the toner particles adherin to belt would be removed by a toner such as as 26 in Figure without the present it can be readily appreciated that excessive steps must be taken to provide for toner within such a machine thereby presenting a serious solids handling with a concomitant excessive consumption of toner While the present has been described with reference to th incorporation of two pairs of slits in it wil be stood that or three more pairs of may be provided depending on the design capabilities of it will be understood that a exposure be provided having at one end thereof instead of at both ends dependent on the reference positioning of the document on the platen as well as the optic system to be in the apparatus of the present while described by way of example with reference to a high speed machine an endless belt being continuously can also be in the form for a electrostatographic and furthermore the orientation in which the receiving members are transported through the apparatus of the invention can be varied in any suitable Discharge other than fluorescent lamps may be employed in the apparatus of the present While the present invention has bee described herein in terms of specific embodiments it is not desired to be limited bu it is intended to cover broadly within the scope of the appended insufficientOCRQuality

Claims (1)

1. 2. CLAIMS electrostatic reproduction machine a movable photoconductive to an static latent on the photoconductivo developing positioned at development to develop said electrostatic latent and transfer positioned at a transfer zone to effect transfer of the developed electrostatic image receiving the including discharge device adapted when activated discharge a area on least margin Of said photoconductive surface prio to development of said laten and means operatively associated with said discharge device for controlling activation of said discharge in response the size of said image receiving The electrostatic reproduction of discharge device positioned substantially discharge said charged on or margins afte exposure of said photoconductive electrostatic reproduction machine of Claim 1 or Claim wherein means for controlling the activation of discharge comprises control means coupled to said discharge device for activatin said discharge in response to predetermined electrical and signal generating responsive to the sire of said receiving member for generating said predetermined electrical image receiving member is of a predetermined said signal generating means being electrostatic reproduction machine of farther comprising an supply wherein said signal generating includes means positioned at supply station fo sensing a dimension of an image receiving accommodated said said switch means developing said electrical signal whe said predetermined is less than a electrostatic reproduction machine of any one of Claims 1 to said discharge device discharges charged areas on opposed margins of said photoconductive reproductio o any one of Claims 1 to wherein said discharge device is disposed adjacent to said photoconductive surface and includes housing having a pair of slits adjacent opposing ends of said housing and an illumination device positioned within said housing adjacent said said device being activated by said control means for discharging charged areas on two opposed margins of said photoconductive electrostatic reproduction machine of 3. Claim 3 or said discharge device is disposed adjacent to said photoconductive surface and includes a housing having two pairs of the slits of each pair being adjacent opposed ends said and a of illumination devices each positioned within said housing adjacent different pair of said the reproduction machine further comprising a pair of said control means and an associated pair of said signal generating of illumination devices being activated associated one of said pair of control means for discharging charged areas on two opposed said photoconductive the margins discharged by one of said devices being of different from width of discharged by the other of said illumination electrostatic reproduction substantially as hereinbefore described reference to the accompanying insufficientOCRQuality