CUTTER ASSEMBLY
United States Patent 3743409
Cutter assembly for an electrostatographic machine using a continuous web of transfer material in which the metering web of the cutter assembly is driven by the drive for the drum of the machine and the cutter is driven by the metering roll. In response to an increase in web tension, the metering roll is allowed to slip with respect to the drum to relieve tension, thereby providing uniform web tension without affecting the accuracy of the cut.
US Patent References:
Loop control fluid operated means for regulating the speed of a cutting means to cut uniform lengths
Rauline - May 1960 - 2934987
IMAGING APPARATUS
Egnaczak - September 1971 - 3609028
Rotary shearing apparatus
MacFarren - April 1940 - 2195653
Loop control fluid operated means for regulating the speed of a cutting means to cut uniform lengths
Rauline - May 1960 - 2934987
IMAGING APPARATUS
Egnaczak - September 1971 - 3609028
Rotary shearing apparatus
MacFarren - April 1940 - 2195653
Application Number:
05/152097
Publication Date:
07/03/1973
Filing Date:
06/11/1971
View Patent Images:
Export Citation:
Assignee:
Xerox Corporation (Stamford, CT)
Primary Class:
Other Classes:
83/336, 83/312
International Classes:
B26D1/38; B65H23/188; G03G15/00; B26D1/01; G03G15/00
Field of Search:
355/13,28,29 83/336,312,298
Primary Examiner:
Greiner, Robert P.
Claims:
1. The apparatus of claim 1 wherein the control means includes means selectively engaging and disengaging the driving connection between the metering means and the drive means to maintain said substantially uniform
Description:
This invention relates to cutting of a continuous web and more particularly to a cutter assembly which provides for uniform web tension. Still more particularly, this invention relates to the cutting of a continuous web from an electrostatographic machine having a developed image thereon.
In electrostatographic machines employing a continuous web as the support material to which the developed image is transferred, the web, after transfer of the image thereto, is preferably automatically cut by a cutter mechanism incorporated into or attached to the machine whereby the final copy is delivered from the machine in individual sheet form. In such machines, control means are provided to control the cutter whereby the cutter accurately cuts the web in relation to both the leading and trailing edge of the reproduction, as exemplified by U. S. Pat. No. 3,105,425 to Ceresani et al; U. S. Pat. No. 3,075,493 to Ceresani et al.
In machines for producing multiple copies of an original in order to maintain a desired repeat cut length along the web, the web should be introduced into the cutter under a substantially uniform predetermined tension, notwithstanding the tension varying effects of changes in other conditions. In addition, the maintenance of a predetermined web tension is important during the transfer of the powder image to the web in order to prevent smearing of the image on the web.
Accordingly, the principal object of the present invention is to provide a cutter assembly and control which maintains uniform web tension.
In accordance with one aspect of the present invention there is provided a cutting apparatus for cutting a web under substantially uniform web tension in which the web is metered from a feeding means to the cutter by a metering means and the web tension is maintained substantially uniform by selectively changing, in response to changes in web tension, the speed at which the metering means meters the web to the cutter with respect to the speed at which the feeding means feeds the web to the metering means. The means for feeding the web to the metering means and the metering means are preferably driven by a single drive means and the surface speed of the metering means is preferably changed by selectively engaging and disengaging the driving connection between the metering means and the drive to maintain a substantially uniform web tension.
More particularly, the cutting apparatus is specifically suited for cutting a continuous web, having a powder image thereon, fed to a metering means from an electrostatographic recording member. The drive means for the electrostatographic recording member also drives the metering means, preferably a metering roll, the drive means driving the metering means at a surface speed which is slightly greater than the surface speed of the recording member. In response to a change in web tension, the surface speed of the metering means is changed with respect to the surface speed of the recording member to maintain a predetermined substantially uniform web tension. The metering means preferably also drives the cutter, preferably a rotary cutter, at a predetermined surface speed ratio, which determines the length of the cut. In this manner, a change in the speed of the metering means, to provide for substantially uniform web tension, has no effect on the surface speed ratio between the metering means and the cutter and, accordingly, there is no change in the length of the cut.
The change of surface speed of the metering means with respect to the surface speed of the recording member may be effected by any of a wide variety of speed control means, preferably a clutch or an electric brake, more preferably an electric clutch, which decreases the surface speed of the metering roll, in response to an increase in web tension, by interrupting the driving connection between the metering means and its drive means, to thereby decrease the web tension and maintain a substantially uniform web tension.
The invention will be further described with respect to an embodiment thereof illustrated in the accompanying drawings wherein like numerals represent like parts and wherein:
FIG. 1 is a simplified schematic representation of an electrostatographic machine incorporating a cutter assembly of the present invention;
FIG. 3 is a top view of the cutter assembly of FIG. 2; and
FIG. 4 is a simplified schematic representation of an operating circuit for the embodiment of the cutter assembly illustrated in FIG. 2.
Referring to FIG. 1 of the drawings, there is illustrated an electrostatographic machine employing one embodiment of this invention. The machine includes an image forming member such as, for example, an electrophotographic cylinder designated 10 and generally comprising a photoconductive insulating layer disposed on a conductive backing. The cylinder is rotatably mounted on a suitable axle 11 or other bearing member and is adapted to be rotated by drive means such as, for example, an electric motor 12. Preferably the cylinder, and in particular its conductive backing, is electrically grounded. The image forming or image receiving surface of the electrophotographic cylinder 10 is adapted to be rotated past appropriate electrophotographic processing stations disposed and positioned to form an electrostatic image on the cylinder surface. For example, when used with a photoconductive insulating electrophotographic image surface, the electrophotographic processing stations may include means for charging or sensitizing, exposure means, and cleaning means. Illustrated in the figure is a charging station generally designated 14 at which is positioned a corona discharge electrode 15, desirably one or more high voltage corona discharge wires 16 mounted within a grounded shield 17 and adapted to be connected to a high voltage source such as, for example, a positive polarity direct current source of several thousand volts. In general the voltage applied to the corona discharge electrode will be sufficient to cause air ionization surrounding the corona wires and it is understood that such a corona discharge potential is generally in the order of several thousand volts and usually 5 to 10 thousand volts as disclosed, for example, in Walkup U. S. Pat. No. 2,777,957.
Positioned next adjacent to the charging station is an exposure station generally designated 18 and including suitable means for projecting or otherwise directing a light or optical image onto the surface of the electrophotographic drum. The exposure station may include a slit projection mechanism for exposing onto the drum surface a moving projected image of microfilm or the like, and may include means for projecting onto the surface documentary or other information or an image corresponding to the face of a cathode ray tube or the like. As is disclosed in Carlson U. S. Pat. No. 2,297,691, the combination of electric field and exposure to activating radiation forms on the drum surface an electrostatic image capable of being developed or made visible by deposition of finely divided charged particles.
A development station for developing the latent electrostatic image, generally designated as 21, is positioned at a subsequent location around the circumference of the drum. The development station, as shown, includes a sump 22 containing a two component developer material comprised of toner and carrier, for example of the type disclosed in U.S. Pat. No. 2,618,551 to Walkup; a conveyor 23, which is driven through suitable drive means by a motor 24; and a chute 25 for transporting developer released from the conveyor to the surface of the drum 10. In operation, the conveyor 23 transports the developer from the sump 22 to the chute 25, and the developer released from the chute 25 cascades over the surface of the drum 10, whereby the toner particles are attracted to the image areas previously formed thereon to render the image visible. The unused developer material which has cascaded over the surface of the drum 10 falls into the sump 22, and the developer material in the sump 22 is periodically provided with toner to replenish the toner used to develop the image.
Positioned subsequently around the surface of the electrophotographic drum is an image transfer station generally designated 27 including, for example, a supply roll 28 of transfer material such as, for example, a roll of paper together with guide means and the like to feed the image transfer material into contiguous relationship with the electrophotographic drum. As illustrated in FIG. 1, suitable guide rolls 30 may guide the transfer web into contact with the electrophotographic drum, and transfer means such as, for example, a corona discharge electrode 31 is positioned to transfer the developer image to the image web at the transfer station. The drum 10 in conjunction with the guide rolls functions as a feed means for feeding the web having the transferred image thereon to the fuser, hereinafter described. In this manner the rate of web movement is identical to the surface speed of the drum 10. Preferably, the transfer means is a corona discharge electrode of substantially the same construction as is located at the charging station 14 although other transfer means may be employed such as the means disclosed in U.S. Pat. No. 2,807,233. For the usual case of direct or positive-to-positive photographic copy the charging electrode 15 and the transfer electrode 31 are of the same polarity and for the opposite situation of photographic reversal the electrodes are of opposite polarity. Optionally positioned near the transfer station and along the line of travel of the transfer web subsequent to the transfer station is a d control means responsive to web tension for maintaining a substantially uniform web tension, said control means selectively changing the speed at which the metering means meters the web to the cutting means with respect to the speed at which the web is fed to the metering means from the recording member to thereby maintain a substantially uniform web tension.
In electrostatographic machines employing a continuous web as the support material to which the developed image is transferred, the web, after transfer of the image thereto, is preferably automatically cut by a cutter mechanism incorporated into or attached to the machine whereby the final copy is delivered from the machine in individual sheet form. In such machines, control means are provided to control the cutter whereby the cutter accurately cuts the web in relation to both the leading and trailing edge of the reproduction, as exemplified by U. S. Pat. No. 3,105,425 to Ceresani et al; U. S. Pat. No. 3,075,493 to Ceresani et al.
In machines for producing multiple copies of an original in order to maintain a desired repeat cut length along the web, the web should be introduced into the cutter under a substantially uniform predetermined tension, notwithstanding the tension varying effects of changes in other conditions. In addition, the maintenance of a predetermined web tension is important during the transfer of the powder image to the web in order to prevent smearing of the image on the web.
Accordingly, the principal object of the present invention is to provide a cutter assembly and control which maintains uniform web tension.
In accordance with one aspect of the present invention there is provided a cutting apparatus for cutting a web under substantially uniform web tension in which the web is metered from a feeding means to the cutter by a metering means and the web tension is maintained substantially uniform by selectively changing, in response to changes in web tension, the speed at which the metering means meters the web to the cutter with respect to the speed at which the feeding means feeds the web to the metering means. The means for feeding the web to the metering means and the metering means are preferably driven by a single drive means and the surface speed of the metering means is preferably changed by selectively engaging and disengaging the driving connection between the metering means and the drive to maintain a substantially uniform web tension.
More particularly, the cutting apparatus is specifically suited for cutting a continuous web, having a powder image thereon, fed to a metering means from an electrostatographic recording member. The drive means for the electrostatographic recording member also drives the metering means, preferably a metering roll, the drive means driving the metering means at a surface speed which is slightly greater than the surface speed of the recording member. In response to a change in web tension, the surface speed of the metering means is changed with respect to the surface speed of the recording member to maintain a predetermined substantially uniform web tension. The metering means preferably also drives the cutter, preferably a rotary cutter, at a predetermined surface speed ratio, which determines the length of the cut. In this manner, a change in the speed of the metering means, to provide for substantially uniform web tension, has no effect on the surface speed ratio between the metering means and the cutter and, accordingly, there is no change in the length of the cut.
The change of surface speed of the metering means with respect to the surface speed of the recording member may be effected by any of a wide variety of speed control means, preferably a clutch or an electric brake, more preferably an electric clutch, which decreases the surface speed of the metering roll, in response to an increase in web tension, by interrupting the driving connection between the metering means and its drive means, to thereby decrease the web tension and maintain a substantially uniform web tension.
The invention will be further described with respect to an embodiment thereof illustrated in the accompanying drawings wherein like numerals represent like parts and wherein:
FIG. 1 is a simplified schematic representation of an electrostatographic machine incorporating a cutter assembly of the present invention;
FIG. 3 is a top view of the cutter assembly of FIG. 2; and
FIG. 4 is a simplified schematic representation of an operating circuit for the embodiment of the cutter assembly illustrated in FIG. 2.
Referring to FIG. 1 of the drawings, there is illustrated an electrostatographic machine employing one embodiment of this invention. The machine includes an image forming member such as, for example, an electrophotographic cylinder designated 10 and generally comprising a photoconductive insulating layer disposed on a conductive backing. The cylinder is rotatably mounted on a suitable axle 11 or other bearing member and is adapted to be rotated by drive means such as, for example, an electric motor 12. Preferably the cylinder, and in particular its conductive backing, is electrically grounded. The image forming or image receiving surface of the electrophotographic cylinder 10 is adapted to be rotated past appropriate electrophotographic processing stations disposed and positioned to form an electrostatic image on the cylinder surface. For example, when used with a photoconductive insulating electrophotographic image surface, the electrophotographic processing stations may include means for charging or sensitizing, exposure means, and cleaning means. Illustrated in the figure is a charging station generally designated 14 at which is positioned a corona discharge electrode 15, desirably one or more high voltage corona discharge wires 16 mounted within a grounded shield 17 and adapted to be connected to a high voltage source such as, for example, a positive polarity direct current source of several thousand volts. In general the voltage applied to the corona discharge electrode will be sufficient to cause air ionization surrounding the corona wires and it is understood that such a corona discharge potential is generally in the order of several thousand volts and usually 5 to 10 thousand volts as disclosed, for example, in Walkup U. S. Pat. No. 2,777,957.
Positioned next adjacent to the charging station is an exposure station generally designated 18 and including suitable means for projecting or otherwise directing a light or optical image onto the surface of the electrophotographic drum. The exposure station may include a slit projection mechanism for exposing onto the drum surface a moving projected image of microfilm or the like, and may include means for projecting onto the surface documentary or other information or an image corresponding to the face of a cathode ray tube or the like. As is disclosed in Carlson U. S. Pat. No. 2,297,691, the combination of electric field and exposure to activating radiation forms on the drum surface an electrostatic image capable of being developed or made visible by deposition of finely divided charged particles.
A development station for developing the latent electrostatic image, generally designated as 21, is positioned at a subsequent location around the circumference of the drum. The development station, as shown, includes a sump 22 containing a two component developer material comprised of toner and carrier, for example of the type disclosed in U.S. Pat. No. 2,618,551 to Walkup; a conveyor 23, which is driven through suitable drive means by a motor 24; and a chute 25 for transporting developer released from the conveyor to the surface of the drum 10. In operation, the conveyor 23 transports the developer from the sump 22 to the chute 25, and the developer released from the chute 25 cascades over the surface of the drum 10, whereby the toner particles are attracted to the image areas previously formed thereon to render the image visible. The unused developer material which has cascaded over the surface of the drum 10 falls into the sump 22, and the developer material in the sump 22 is periodically provided with toner to replenish the toner used to develop the image.
Positioned subsequently around the surface of the electrophotographic drum is an image transfer station generally designated 27 including, for example, a supply roll 28 of transfer material such as, for example, a roll of paper together with guide means and the like to feed the image transfer material into contiguous relationship with the electrophotographic drum. As illustrated in FIG. 1, suitable guide rolls 30 may guide the transfer web into contact with the electrophotographic drum, and transfer means such as, for example, a corona discharge electrode 31 is positioned to transfer the developer image to the image web at the transfer station. The drum 10 in conjunction with the guide rolls functions as a feed means for feeding the web having the transferred image thereon to the fuser, hereinafter described. In this manner the rate of web movement is identical to the surface speed of the drum 10. Preferably, the transfer means is a corona discharge electrode of substantially the same construction as is located at the charging station 14 although other transfer means may be employed such as the means disclosed in U.S. Pat. No. 2,807,233. For the usual case of direct or positive-to-positive photographic copy the charging electrode 15 and the transfer electrode 31 are of the same polarity and for the opposite situation of photographic reversal the electrodes are of opposite polarity. Optionally positioned near the transfer station and along the line of travel of the transfer web subsequent to the transfer station is a d control means responsive to web tension for maintaining a substantially uniform web tension, said control means selectively changing the speed at which the metering means meters the web to the cutting means with respect to the speed at which the web is fed to the metering means from the recording member to thereby maintain a substantially uniform web tension.