US3902062A

US3902062A - Reverse path imaging and transfixing copying method

Info

Publication number: US3902062A
Application number: US428934A
Authority: US
Inventors: Roger H Eichorn
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1973-12-27
Filing date: 1973-12-27
Publication date: 1975-08-26
Anticipated expiration: 1992-08-26
Also published as: BE823656A; DE2453887A1; CA1028749A; NL7415558A; JPS5099555A; FR2256446B1; FR2256446A1

Abstract

Cut sheets of heat sensitive material are employed in carrying out a reverse path thermographic copying process wherein the imaging and fusing (a non-transfer mode of operation) or transfixing (a transfer mode of operation) are performed at a first station in response to radiant energy from a single source on a pre-development and post-development basis, respectively.

Description

United States Patent 1191 Eichorn, deceased [4 1 Aug. 26, 1975 REVERSE PATH IMAGING AND TRANSFIXING COPYING METHOD [75] Inventor: Roger H. Eichorn. deceased, late of Rochester, NY., by Lincoln First Bank of Rochester, executor [73] Assignee: Xerox Corporation, Stamford,

Conn.

22 Filed: Dec. 27, 1973 [21] Appl. No.: 428,934

52 US. (:1. ..250/318; 101/470;-250 319; 355/3 DD 51 Int. Cl. H0lj 37/26 [58] Field of Search ..250/316,317,31s,319; 101/470, DIG. 13-, 355/3 DD, 16

[56] References Cited UNITED STATES PATENTS 3,048,695 8/1962 Russell 250/3 l 8 Dulmagc 250/317 Jarvis l0l/470 Primary Examiner-James W, Lawrence Assistant Examiner--D. C. Nelms [57] ABSTRACT Cut sheets of heat sensitive material are employed in carrying out a reverse path thermographic copying process wherein the imaging and fusing (a nontransfer mode of operation) or transfixing (a transfer mode of operation) are performed at a first station in response to radiant energy from a single source on a pre-development and post-development basis, respectively.

8 Claims, 3 Drawing Figures PATENTEI] AUG 2 6 I975 SEIKU 1 BF 2 PATENTED Auszsms va \JilLLl REVERSE PATH IMAGING AND TRANSFIXING COPYING METHOD CROSS-REFERENCE TO RELATED APPLICATIONS This application is related to the following copending and commonly assigned applications:

Serial No.

Applicant Filing Date Lincoln First Bank of Rochester. Executor for Roger H. Eichorn James D. Rees et al. Lincoln First Bank of Rochester. Executor for Roger H.'Eichorn Myron .I. Lenhard Lincoln First Bank of Rochester. Exeuctor for Roger H. Eichorn Lincoln First Bank of Rochester Executor for Roger H. Eichorn DESCRIPTION OF THE INVENTION are conventionally carried out at separate stations.

If the imaging and fusing or transfixing stations are equipped with separate heat sources. separate control mechanisms and transport mechanisms must be provided, and those mechanisms must be synchronized so that the functions at each station are efficiently carried out. Obviously, this requires duplication of parts and a more complicated system.

When the same heat source is provided for both stations, one is limited to the same lamp intensity for both functions or the machine must be larger so that the lamp may be changed to a different intensity for either fusing or transfixing after imaging.

It is an object of this invention to provide a copying method which permits the use of an inexpensive, simple compact copying device utilizing a cut sheet heat sensitive material.

It is proposed to accomplish the above object by using the same lamp and station for the imaging and the fusing or transfixing functions.

Other objects of the invention will become apparent when the following description in conjunction with the drawings wherein:

FIG. 1 is a schematic view of a copying apparatus showing the imaging and developing step;

FIG. 2 is a partial view of the copying apparatus of FIG. 1 illustrating the position of a heat sensitive member after an image thereon has been developed; and

FIG. 3 is a view of the apparatus of FIG. I showing a developed image transfer step.

Referring to the drawings. a copying apparatus I0 has a guide slot 12 for receiving a sandwich of a heat sensitive sheet 14 and an original sheet 16 with an image thereon. The heat sensitive sheet 14 comprises a support with a heat sensitive coating. For example, the support may be anorganic film. such as a polyester film. cellulose acetate or triacetate film, coated with a delayed tack adhesive which is normally hard and nontacky at room temperature. but which, upon being activated by heat to a tacky condition and subsequently cooled to room temperature. thereafter remain tacky for considerable periods of time varying from at least 30 seconds to several days or more depending upon the particular composition involved. Such delayed tack coatings are well known and can be a mixture of discrete particles or resin, such as indene resin or esterfied resin, and discrete particles of crystalline plasticizer. such as diphenyl phthalate or N-cyclohexyl paratoluene sulfonamide. The particles are bound together into the supporting film by a binder. such as styrenebutadiene copolymer. Generally speaking. the crystalline plasticizer component of the mixture is in excess of the resin component.

A cylinder 18 having a highly reflective surface is rotatably mounted on the frame of the machine and a transparent belt 20 rotates around three

idler rolls

22, 24, 28 and a drive roll 26. The cylinder 18 and the drive roll 26 are driven by a reversible motor (not shown). The

rolls

24 and 26 are arranged so that the belt 20 is pressed against the cylinder 18 to form nips 25 and 27, respectively. A microswitch (not shown) is located in the slot 12 and is electrically connected to the reversible motor for starting the same and is arranged to be actuated upon insertion of sheets into the slot. Upon rotation of the cylinder 18, the belt 20 will be rotated therewith and pressed against the surface of the cylinder. A radiation source, such as an incandescent lamp 30, is arranged opposite the cylinder 18 to apply radiant heat to the region of the cylinder 18 which is opposite the lamp. A delay mechanism is employed to turn the lamp on and off at the proper time. Upon insertion of the original sheets 16 and the heat sensitive member 14 as a sandwich into the slot I2 and into engagement with the nip 27. the sandwich will be pulled past the lamp 30. A slot 31 is provided through which the original sheet 16 emerges after being separated from sheet 14. A sheet separator 33 is located at the entrance of the slot 31 and is under vacuum during a period necessary to attract the original thereto. thereby separating the same from the heat sensitive sheet 14.

A conveyor mechanism which comprises a belt 32 trained around a drive roll 34 and an idler roll 36. is located to coact with a roll 38 which forms a pressure nip therebetween to grip the leading edge 39 of the heat sensitive sheet I4 to drive the same along a guide member 40 to a developer station which comprises a housing 4] having ferromagnetic toner particles 42 therein. The drive roll 34 is driven by the same motor that drives the cylinder 18. A well known magnetic brush 44 is mounted on the housing 41 to have a portion rotatable in the toner bed 42 and a portion arranged to engage the heat sensitive sheet I4 to present toner thereto to develop the image thereon. The magnetic brush 44 is also connected to the reversible motor which drives the cylinder I8 and the drive roll 34. The toner parti cles 42 comprise thermoplastic particles pigmented with carbon black or other radiation absorbing dyes or pigments, and mixed with iron oxide particles.

A storage slot 50 is provided to receive the leading edge 39 of the heat sensitive sheet 14 after the same has passed the development station. The idler roll 36 is arranged relative to the surface 51 of the slot 50 that the belt 32 makes slight contact with the surface 51 to grip the heat sensitive sheet 14 therebetween to move the same. A microswitch 52 is located at the upper end of the storage slot 50 and is electrically connected to the reversible motor (not shown) which is connected to the cylinder 18, the drive roll 34 and the magnetic brush 44. The switch 52 is arranged to be engaged by the leading edge 39 of the heat sensitive sheet 14. The location of the idler roll 36 is such that the trailing edge 53 of the heat sensitive sheet 14 will be engaged by the belt 32 when the switch 52 is actuated by the leading edge 39. When the switch 52 is actuated, reversal of the motor is effected which in turn effects reversal of rotation of the drive roll 34, the magnetic brush 44 and the cylinder 18 to cause the reversal of movement of the heat sensitive sheet 14 out of the storage slot 50 past the development station and guide 40 up to the nip 27 and around the cylinder 18 past the lamp 30 and out of the machine through slot 12.

A supply of copy paper 54 is arranged on a paper tray 56 and a feed roll 58 is arranged to engage the uppermost one of the stack of copy papers 54 to drive the same away from the stack along a guide member 60 to a pair of nip rolls 62. A torsion spring 61 biases the paper tray 56 toward the feed roll 58 and thereby brings the stack of copy paper into engagement with the feed roll. The microswitch 52 is also electrically connected to a motor for driving the feed roll 58 and to another motor for driving the nip rolls 62 and to a motor for supplying vacuum to the separator 33. Upon actuation of the micro-switch 52 by the leading edge of the heat sensitive sheet 14, the vacuum motor is turned off, the motor for the feed roll 58 is actuated to drive the same and a delay mechanism (not shown) for starting the nip rolls 62 is actuated to start the nip rolls 62 after the leading edge of a copy sheet 54 is in engagement therewith and after the heat sensitive sheet 14 has moved in a reverse direction for a certain distance. A delay mechanism (not shown) is also employed for turning off the motors for the feed roll 58 and for the nip rolls 62 at the appropriate time. The nip rolls 62, drive the copy sheet 54 into a guide 64 which leads the copy sheet to the nip 27. This is so timed that the leading edge of the copy sheet 54 arrives just prior to the nip 27 at the same time as the former trailing edge 53, but now the leading edge, of the heat sensitive sheet 14 arrives thereat so that the two sheets will be aligned and moved by the cylinder 18 between the cylinder 18 and the belt past the lamp and out of the copying apparatus through slot 12 as a sandwich. A delay mechanism is timed to turn off the reversible motor for the cylinder 18 and the drive roll 34 after the

sheets

14 and 54 emerge from the slot 12.

In operation, referring to FIG. 1, a heat sensitive sheet 14 and an original sheet 16 having an image thereon to be copied are placed together to form a sandwich and inserted into slot 12 to actuate the switch in the slot 12 to start the cylinder 18, belt 32 and the magnetic brush 44 rotating in the direction shown. The sandwich is fed between the cylinder 18 and the belt 20 past the incandescent lamp 30 and is exposed to the lamp 30. The intensity of the lamp and the speed at which the sandwich passes thereby is such as to cause sufficient heat to create a tacky image on the heat sensitive member corresponding to the image on the origi nal sheet 16. As the leading edge of the sandwich emerges from between the belt 20 and the cylinder 18, the original is separated from the heat sensitive sheet 14 by vacuum separator 33 and is discharged from the copying apparatus through the slot 31. The heat sensitive sheet 14 continues to the development station whereby the magnetic brush 44 dusts toner particles 42 onto the tacky image. Referring to FIG. 2, the developed heat sensitive sheet 14 passes into the storage slot 50 and the leading edge 39 thereof engages the microswitch 52 which causes reversal of rotation of the belt 32, the magnetic brush 44, and the cylinder 18 and actuation of the paper feed roll 58 and the delay mechanism for actuating the nip rolls 62. Referring to FIG. 3, upon reversal of the belt 32, the heat sensitive sheet 14 is removed from the storage area 50 with the former trailing edge 53 now being the leading edge. The sheet 14 is passed through the developer station wherein magnetic brush 44 presents particles to the image to develop the image with more toner particles if necessary. At this point, the leading edge of a copy paper 54 has been moved to the nip rolls 62 and the delay mechanism now actuates the nip rolls 62 to drive the copy sheet 54 to arrive just prior to the nip 27 at the same time as the leading edge 52 of the heat sensitive sheet 14. The two sheets enter the nip 27 between the cylinder 18 and the belt 20 as a sandwich and are exposed to the incandescent lamp 30 for a sufficient amount of time to melt the toner particles whereby a substantial portion thereof transfer from the heat sensitive sheet to the copy sheet and are fixed thereto due to the slight pressure between the sheets caused by the pressure between the belt 20 and cylinder 18. Then the sandwich is passed out of the copying apparatus through the slot 12 whereupon an operator takes the sandwich and sep-' arates the sheets to obtain the copy of the image on the original.

Inasmuch as the imaging and transfixing functions are separated not only by the development step but also by the storage of the heat sensitive sheet, provision may be made, if desired, to change the rate at which the heat sensitive sheet is advanced past the lamp and/or the intensity of the lamp during the interval of time that separates the imaging and transfixing operations.

Rather than employing a transfer mode of operation, a non-transfer mode may be used wherein, the developed image is fused directly on the heat sensitive sheet 14 with the heat sensitive sheet being the copy itself. In that event, the cylinder 18, which will be contacted by the toner particles during the fixing or fusing step, must comprise a material to which melted toner particles will not stick. Alternatively, a stack of release sheets could be placed on the paper tray 56 and fed past the lamp 30 in contact with the developed image. In this latter case, the release sheet will be of a material to which the toner particles will not stick.

The control system and the components thereof for operating the machine as described are all well known and well within the grasp of one having ordinary skill in the art and therefore have not been shown.

What is claimed is:

l. A thermographic copying method comprising the steps of bringing a cut sheet of heat sensitive material into contact with an original bearing an image. to form a sandwich;

moving the sandwich in a first direction along a predetermined path extending through a first station and a remotely spaced development station;

exposing said sandwich at said first station to radiation from a radiant source to thermally impart said image to said sheet;

separating said original from said sheet at a point between said first station and said development station;

passing said sheet through said development station to at least partially develop said image while continuing to move said sheet in said first direction along said path;

moving said sheet in the opposite direction along said path back through said development station and said first station; and

re-exposing said sheet at said first station to radiation from said source to fix said image.

2. The method as recited in claim 1 wherein said image is further developed as said sheet moves back through said development station in said opposite direction.

3. The method as recited in claim I wherein one edge of said sheet is leading when said sheet is moving in said one direction and trailing when said sheet is moving in said opposite direction.

4. The method as recited in claim 1 wherein said image is developed by applying resinous toner thereto.

5. The method as recited in claim 1 further including the additional step of depositing said sheet in a storage area after said sheet is moved through said development station in said one direction and before said sheet is moved back through said development station in said opposite direction.

6. The method as recited in claim 1 wherein resinous toner is applied to the image imparted to said sheet as said sheet is moved through said development station in said first direction and said opposite direction to thereby develop said image.

7. The method as recited in claim 1 further including the step of bringing said heat sensitive sheet into contact with a copy sheet at a point between said first station and said development station while said heat sensitive sheet is moving in said opposite direction along said path; and wherein said heat sensitive sheet is re-exposed while in contact with said copy sheet whereby said image is transfixed onto said copy sheet.

8. A method as recited in claim 1 wherein said image is fixed onto the heat sensitive sheet by the re-exposure step.

Claims

1. A thermographic copying method comprising the steps of bringing a cut sheet of heat sensitive material into contact with an original bearing an image, to form a sandwich; moving the sandwich in a first direction along a predetermined path extending through a first station and a remotely spaced development station; exposing said sandwich at said first station to radiation from a radiant source to thermally impart said image to said sheet; separating said original from said sheet at a point between said first station and said development station; passing said sheet through said development station to at least partially develop said image while continuing to move said sheet in said first direction along said path; moving said sheet in the opposite direction along said path back through said development station and said first station; and re-exposing said sheet at said first station to radiation from said source to fix said image.

3. The method as recited in claim 1 wherein one edge of said sheet is leading when said sheet is moving in said one direction and trailing when said sheet is moving in said opposite direction.

7. The method as recited in claim 1 further including the step of bringing said heat sensitive sheet into contact with a copy sheet at a point between said first station and said development station while said heat sensitive sheet is moving in said opposite direction along said path; and wherein said heat sensitive sheet is re-exposed while in contact with said copy sheet, whereby said image is transfixed onto said copy sheet.