US3053175A

US3053175A - Thermocopying machine

Info

Publication number: US3053175A
Application number: US775548A
Authority: US
Inventors: Otto R Urbach
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1958-11-21
Filing date: 1958-11-21
Publication date: 1962-09-11
Anticipated expiration: 1979-09-11
Also published as: DE1878291U

Description

p 1962 o. R. URBACH 3,053,175

THERMOCOPYING MACHINE Filed NOV. 21, 1958 F/ci.

Arrows 5m United States Patent Oflice 3,653,175 Patented Sept. 11, 1962 3,053,175 THERMOCOPYING MACHINE Otto R. Urbach, Hosel, near Dusseldorf, Germany, assignor to Minnesota Mining and Manufacturing Company, St. Paul, Minn., a corporation of Delaware Filed Nov. 21, 1953, Ser. No. 775,548 Claims. (Cl. 101-131) This invention relates to the reproduction of graphic originals of the nature of printed or written matter, sketches, drawings and the like, and more. particularly relates to an improved machine for accomplishing such reproduction.

Thermocopying involves the reproduction of graphic Originals by subjection of the original to brief intense irradiation while in heat conductive pressure contact with a sheet of heat sensitive copying paper. One method of thermocopying is disclosed in Miller Patent No. 2,740,- 896, and apparatus for carrying out such methods is described therein, as well as in Miller Patent No. 2,740,895. Typical heat sensitive copying paper which has found particular utility in connection with thermographic reproduction of the type with which the present invention is concerned is described in Miller and Clark Patents Nos. 2,663,654, 2,663,655, 2,663,656 and 2,663,657.

Certain prior art thermocopying machines, for example such as are described in Kuhrmeyer et al. U.S. application Serial No. 497,136, filed March 28, 1955, now U.S. Patent No. 2,891,165, utilize means including a unidirectionally driven endless type of belt or web of flexible transparent material for the purpose of conveying a composite of a graphic original and a copy sheet to and from a copy station at which said composite is subjected to brief intense irradiation applied through the transparent belt. An endless type of belt suitable for use in thermocopying machines of the aforementioned type must be optically uniform, and therefore irregularities such as splice marks therein cannot be tolerated. This requirement of optical uniformity limits the availability of suitable belts to specialized sources of supply which may not be readily accessible in certain localities. Moreover in endless belt type thermocopying machines, means must be provided for continuous correction of any misalignment which may occur between the belt and the rolls or drums on which the belt is supported, otherwise such misalignment may tend to be compounded on continuous operation to the extent of jamming the machine with resultant wrinkling and stoppage of the belt and possible burning of the belt under the intense radiation.

Thermocopying machines constructed in accordance with the present invention are characterized by novel means, including an inexpensive and readily available web or belt of the type having spaced end portions, as distinguished from an endless type of belt or web, for conveying a composite original-copy sheet to and from the copy station. More specifically the improved thermocopying machines have embodied therein conveying means including a reciprocating web or belt which during an operational cycle is advanced along a prescribed path in one direction, and following irradiation of the composite, is returned along the same path to its initial position. completing the operational cycle.

The form of the invention selected for illustration can best be described with reference to the drawing accompanying and forming a part of this specification, in which:

FIGURE 1 is semi-diagrammatic vertical sectional view taken from front to back through one form of thermocopying machine constructed in accordance with the inventive concept; and

FIGURE 2 is a fragmentary vertical sectional view of the thermocopying machine of FIGURE 1, viewed from the direction opposite the direction in which FIGURE 1 is viewed, and showing the brake mechanism associated with the take-up roll.

Referring now to FIGURE 1, the improved thermocopying machine is provided with a housing or casing 5 formed in the front thereof with an entrance channel 6 and an exit channel 7. Suitably mounted within the casing 5, for rotation on parallel axes in the special relationship shown, are a storage roll 8, a copy roll 9, an idler roll 10 and a take-up roll 11. The rolls 8 to 11 support and provide guiding means defining a prescribed path for a transparent flexible carrier or conveyor web 12 which has its opposite ends fixed at 13 and 14 to the rolls 8 and 1-1 as shown. The storage roll 8 is rotatably mounted on a fixed shaft 15, and shown coaxially surrounding the shaft 15 is a helical torsion type spring 16 having one end anchored to the shaft 15 and the other end anchored to the roll 8. The spring 16 exerts a bias on the roll 8 tending to rotate the latter in a direction to wind the web 12 thereon for storage as shown.

A tubular line-filament lamp 17 is disposed within an open elliptical reflector 18 which is parallel to the copy roll 9, the open face of the reflector being disposed closely adjacent the portion of the web 12 overlaying the roll 9. The filament of the lamp 17 is located along one of the focal lines of the elliptical cross section reflector, the position of the other focal line falling just in front of the surface of the copy roll 12. The lamp 17 and refiector 18alford a copy station at which a composite of a graphic original and a heat-sensitive copy sheet can be strongly and briefly irradiated while being held firmly and smoothly together under pressure contact between the web 12 and copy roll 9. The web .12, in cooperation with the copy roll 9, affords means for conveying the aforementioned composite from the entrance channel 6 into which it is fed, to and from the copy station, discharging said composite from the exit channel 7.

Advancement of the web 12 along its prescribed path in order to afford conveyance of the composite original copy sheet past the copy station in the manner described is afforded by a releasable drive means which is operable to rotate the take-up roll 11 in a direction to wind said web thereon and simultaneously to cause like rotation of the storage roll against the bias of the torsion spring 16 as the web is unwound therefrom. When the web 1.2 has been advanced sufiiciently to effect conveyance of a composite original-copy sheet from the entrance channel 6 past the copy station and out the exit channel, the drive means releases the take-up roll 11 to permit reverse rotation thereof and return of the web 12 to its initial position on storage roll 8 under the bias of the spring 16.

The illustrated drive means is of the variable speed type and includes an electric motor 19 drivingly connected to a shaft 23 having fixed thereon driving gear 20 which is disposed in driving relationship with a driven gear 21. The driven gear 21 is fixed on shaft 22 on which the take-up roll 11 is also fixedly mounted. The driving gear 20 has a peripheral escapement portion 24 which is devoid of gear teeth, and when the portion 24 is presented to the driven gear 21 as shown, the gear 21 and take-up roll 11 are free to rotate independently of the driving gear 20.

1 Control of the drive means and of the lamp 17 is afforded by a master switch 25 interposed in a line conductor 26 connected to one terminal of a line voltage source through a plug 27. The other terminal of the plug 27 is connected to the terminal 19a of the motor 19 by a line conductor 28. Connected in parallel circuit relation with each other between the terminal 1% of the motor 19 and the line conductor 26 are a biased-open start switch 29 and the contacts 30b of a double pole biased-closed stop switch 30. The start switch 29 is interposed in a conductor 31 connected to motor terminal 19b and intersecting the conductor 26 at 51. The stop switch contacts 30b are interposed in a conductor 45 intersecting the

conductors

31 and 26 at 52 and 53 respeclively. The line conductor 26 is also connected to the contacts 30a of stop switch 30 as shown, and a conductor 32 connects the contacts 30ato the motor terminal 19a as shown. High voltage current is supplied to the lamp 17 by a transformer 47 which in the illustrated embodiment is an autotransformer having its common terminal connected to the conductor 32 as at 54 and having a line voltage tap 48 connected to the conductor 31. A condoctor 49 connects one terminal of the lamp 17 in circuit with the conductor 32. A conductor 50 connects the high voltage terminal of the transformer 47 with the other terminal of the lamp 17 and has normally open contacts 44b of relay 44 interposed therein. The energizing winding 44a of relay 44 is interposed in conductor 32.

The start switch 29 has a contact arm 33 crossing the entrance channel 6 in position for actuation to switch closing position by insertion of a composite original-copy sheet into said entrance channel. The stop switch 30 has a; contact arm 34 which is biased into engagement with a cam 35 fixed on the shaft 23 and having a raised peripheral portion or lobe 36. The contact arm 34 is actuated to switch-opening position by engagement of the lobe 36 therewith substantially simultaneously with release of the driven gear 21 by the escapement portion 24 of driving gear 20. Upon movement of the lobe 36 out of engagement with the contact arm 34, said contact arm returns to its normal switch closing position.

Means is provided for retarding the rotation of the take-up roll 11 and thereby the return movement of the web 12 toward the storage roll 8 upon release of the driven gear 21 from the driving gear 20. Referring to FIGURE 2, the end of the shaft 22 opposite that shown in FIGURE 1 has a bushing 37 pressed thereon. Frictionally engaging the bushing 3-7 is the lining 38 of a brake band 39 which has one end anchored at 40. Brake band 39 is biased into engagement with the bushing 37 by a compression spring 41 surrounding an ad ustment screw 42 which is threaded into a fixedly mounted L- shaped bracket 43*.

The operation of the improved thermocopymg machine is as follows:

To ready the machine for operation, the master switch 25 is manually actuated to closed position completing an electrical circuit from one'terminal of the source 27 through the conductor 26 including switch 25, conductor 31, the portion of the transformer winding between tap 48 and common terminal 54, conductor 32 and conductor 28 and thereby energizing the transformer 47. The graphic original, of which a copy is desired, is placed 111 contact with a suitable heat-sensitive copying paper, and

. the composite is fed into the machine through the entrance channel 6. Contact of the composite with the contact arm 33 actuates the start switch 29 to closed position, completing and additional electrical circuit from one terminal of the source 27 to the other through the condoctor 26 including master switch 25, conductor 31 including start switch 29, motor 19, and conductor 28.

This initiates operation of the motor 19 which drives the driving gear 20 and cam 35 in a clockwise direction to move the toothed periphery of the gear 20 into driving relation with the driven gear 21. The resulting counter clockwise rotation of the takeup roll causes winding of the web 12 thereon and simultaneous unwinding of said web from the storage roll 8 as the latter is thereby rotated in a counter clockwise direction against the bias of the torsion spring 16. The composite is drawn between the web 12 and the copy roll 9 and is moved toward the copy station in front of the lamp 17.

Clockwise rotation of the cam 35 moves the lobe 36 out of engagement with the arm 34 of stop switch 30, permitting said arm to raise and contacts 30a and 30b to close. Closure of switch contacts 30a effects energizetion of the relay winding 44a and closure of relay contacts 44b. Closure of relay contacts 44b effects energization of the lamp 17 with high voltage electrical energy. By the time the composite reaches the copy station, the lamp 17 has reached full operating temperature to afford strong and brief irradiation of the composite as it moves through the copy station. During irradiation the sheets of the composite are held firmly and smoothly together under pressure contact between the web 12 and copy roll 9.

As the composite moves out of engagement with the start switch contact arm 33, said contact arm raises to switch opening position. Opening of the switch 29, however, does not shut off the motor 19, since current is now supplied to said motor through the alternate current path through the conductor 45 and switch contacts 30b paralleling that through the conductor 31 and start switch ,29. Thus, advancement of the belt 12 continues, and the composite is conveyed by the web from the copy station at the lamp into the exit channel 7 from which it may be removed.

The radiant energy provided by the lamp 17 and concentrated at the surface of the composite by the reflector 18 is differentially absorbed at the printed surface of the original to provide a differential heat pattern corresponding to the graphic character of the original. This heat pattern develops a reproduction of the original in the heat-sensitive copying paper with which it is in contact. 1

Variations between graphic originals or between types of heat-sensitive copying papers, or in ambient temperatures or line voltages, or other variations such as heat build-up within the machine, require that the rate of passage of the composite past the source of irradiation be controllable in order to maintain proper exposures. T 0 this end, the control knob of the master switch 25 also affords control of suitable electroresponsive or mechanical speed control means (not shown) for varying as required the speed of the motor 19, and hence of the takeup roll 11 and web 12'.

Advancement of the web 12 sufiicient to convey the composite to and-from the copy station and out the exit channel 7 requires substantially one complete revolution of the driving gear 20. At the end of one complete revolution the escapement portion 24 of the driving gear 20 is presented to the driven gear 21, releasing the gear 21, whereupon the torsion spring 16 of the storage roll 8 becomes operative to rewind the web 12 thereon, caus ing reverse travel of said web and reverse rotation of the take-up roll 11. During such release, the brake mechanism shown in FIGURE 2 operates to retard the rotation of the take-up roll and the return movement of the web 12 to its initial position shown in FIGURE 1.

Substantially simultaneously with release of the driven gear 21 by the driving gear 20, the cam lobe 36 moves into engagement with and actuates the contact arm 34 of the stop switch 30, to switch-opening position, terminating operation of the motor 19 and deenergizing relay coil 44a to open the contacts 44b and thereby deenergize the lamp 17. The lamp is thus deenergized during return movement of the web 12, which movement completes one operational cycle of the illustrated machine. The motor 19 and lamp 17 remain deenergized until another composite is inserted at the entrance channel 6 to actuate the start switch 29 and begin a succeeding operational cycle.

While in the illustrated embodiment of the invention one operational cycle of the machine is effective to complete a copy cycle, it is within the concept of the invention to so dimension the various parts that more than one copying cycle are carried out in each operational cycle. In a machine of the latter type only a partial rotation of the driving gear 20 would be required to advance the web an amount sufficient for conveyance of a composite from the entrance channel 6 to and from the copy station and out the exit channel 7. Such a machine may be provided with interchangeable cams 35 having addition-al lobes 36 thereon to interrupt operation of the motor 19 and lamp 17 at predetermined shorter intervals each defining the end of a copying cycle, as well as to interrupt the motor and lamp circuits upon return of gear 20 to its initial position completing an operational cycle of the machine.

The embodiment of the invention shown in' the drawing is for illustrative purposes only, and it is to be expressly understood that said drawing and the accompanying specification are not to be construed as a definition of the limits or scope of the invention, reference being bad to the appended claims for that purpose.

What is claimed as the invention is:

1. Apparatus for reproducing graphic originals comprising means defining a copy station, and means for conveying a composite of a graphic original and a copy sheet to and from said copy station, comprising a web,

guiding means defining a prescribed path for said web, electroresponsive means for advancing a portion of said web along said prescribed path from an initial position toward a second position, first switch means in circuit with said electroresponsive means positioned for actuation by placement of a composite in position for conveyance by said web and operable when actuated to initiate operation of said electroresponsive means, second switch means in circuit with said electroresponsive means and operatively associated therewith for actuation upon predetermined advancement of said web, said second switch means being operable when actuated to terminate operation of said electroresponsive means, and means responsive to said predetermined advancement of said web for effecting return movement of said web along said path toward said initial position.

2. Apparatus for reproducing graphic originals comprising means defining a copy station, and means for conveying a composite of a graphic original and a copy sheet to and from said copy station, comprising a Web, guiding means defining a prescribed path for said Web, means biasing said web in one direction toward an initial position, and electroresponsive drive means for advancing a portion of said web along said prescribed path against the bias of said biasing means toward a second position, said drive means including an escapement type driving gear in driving relation with a driven gear, said driving gear having an escapement portion eifecting interruption of said driving relation upon disposition of said web in said second position, releasing said web for return movement along said path toward said initial position under the bias of said biasing means, first switch means in circuit with said electroresponsive drive means positioned for actuation by placement of a composite in position for conveyance by said web and operable when actuated to initiate operation of said drive means, and second switch means in circuit with said electroresponsive drive means and operatively associated with said driving gear for actuation upon predetermined advancement of said web, said second switch means being operable when actuated to terminate operation of said electroresponsive drive means.

3. Apparatus for reproducing graphic originals comprising means defining a copy station, and means for conveying a composite of a graphic original and a copy sheet to and from said copy station, comprising a storage roll, a take-up roll, a web having one end wound on said storage roll and the opposite end wound on said take-up roll, guiding means defining a prescribed path for said web between said rolls, means biasing said storage roll in a direction tending to wind the web thereon, electroresponsive means operatively associated with said takeup roll for rotating the latter in a direction to withdraw a portion of said web from said storage roll and advance the same along said prescribed path against the bias of said biasing means from an initial position toward a second position, first switch means in circuit with said electroresponsive means positioned for actuation by placement of a composite in position for conveyance by said web and operable when actuated to initiate operation of said electroresponsive means, second switch means in circuit with said electroresponsive means and operatively associated therewith for actuation upon advancement of said web to said second position, said second switch means being operable when actuated to terminate operation of said electroresponsive means, and said drive means being responsive to advancement of said web to said second position to release said take-up roll and thereby permit rewinding of said web on said storage roll under the bias of said biasing means for return of said web along said path toward said initial position.

4. Apparatus for reproducing graphic originals comprising means defining a copy station, and means for conveying a composite of a graphic original and a copy sheet to and from said copy station, comprising a storage roll, a take-up roll, a web having one end wound on said storage roll and the opposite end Wound on said take-up roll, guiding means defining a prescribed path for said web between said rolls, means biasing said storage roll in a direction tending to wind the web thereon, electroresponsive drive means operatively associated with said take-up roll for rotating the latter in a direction to withdraw a portion of said web from said storage roll and advance the same along said prescribed path against the bias of said biasing means from an initial toward a second position, said drive means including an escapement type driving gear in driving relation with a driven gear, said driving gear having an escapement portion effecting interruption of said driving relation upon disposition of said web in said second position, releasing said take-up roll to permit reverse rotation thereof and rewinding of said web on said storage roll under the bias of said biasing means for return of said web along said path toward said initial position, first switch means in circuit with said electroresponsive drive means positioned for actuation by placement of a composite in position for conveyance by said web and operable when actuated to initiate operation of said drive means, and second switch means in circuit with said electroresponsive drive means and operatively associated with said driving gear for actuation upon disposition of said web in its said second position, said second switch means being operable when actuated to terminate operation of said electroresponsive drive means.

5. Apparatus for reproducing graphic originals comprising means defining a copy station, and means for conveying a composite of a graphic original and a copy sheet to and from said copy station, comprising a web,

guiding means defining a prescribed path for said web, means biasing said web in one direction toward an initial position, and electroresponsive drive means for advancing a portion of said web along said prescribed path against the bias of said biasing means toward a second position, said drive means including a driving member in driving relation with a driven member, at least one of said driving and driven members being provided with escapement means efiecting interruption of said driving relation upon disposition of said web in said second position, releasing said web for return movement along said path toward said initial position under the bias of said biasing means, first switch means in circuit with said eiectroresponsive drive means positioned for actuation by placement of a composite in position for conveyance by said web and operable when actuated to initiate operation of said drive means, and second switch means in circuit with said electroresponsive drive means and operatively associated with the latter for actuation upon predetermined advancement of said web, said second switch means being operable when actuated to terminate operation of said electroresponsive drive means.

6. Apparatus for reproducing graphic originals comprising means defining a copy station, and means for conveying a composite of a graphic original and a copy sheet to and from said copy station, comprising a storage roll, a take-up roll, a web having one end wound on said storage roll and the opposite end wound on said takeup roll, guiding means defining a prescribed path for said web between said rolls, means biasing said storage roll in a direction tending to wind the webthereon, electroresponsive drive means operatively associated with said take-up roll for rotating the latter in a direction to withdraw a portion of said web from said storage roll and advance the same along said prescribed path against the bias of said biasing means from an initial toward a second position, said drive means including a driving memher in driving relation with a driven member, at least one of said driving and driven members being provided with escapement means effecting interruption of said driving relation upon disposition of said web in said second position, releasing said take-up roll to permit reverse rotation thereof and rewinding of said web on said storage roll under the bias of said biasing means for return of said web along said path toward said initial position, first switch means in circuit with said electroresponsive drive means positioned for actuation by placement of a composite in position for conveyance by said web and operable when actuated to initiate operation of said drive means, and second switch means in circuit with said electroresponsive drive means and operatively associated with the latter for actuation upon disposition of said web in its said second position, said second switch means being operable when actuated to terminate operation of said electroresponsive drive means.

7. Apparatus for reproducing graphic originals comprising means defining a copy station, and means for conveying a composite of a graphic original and a copy sheet to and from said copy station, comprising a storage roll, a take-up roll, a web having one end portion wound on said storage roll and the opposite end wound on said take-up roll, guiding means defining a prescribed path for said web between said rolls and including a copy roll at said copy station over which said web is trained in continuous frictional engagement effecting corresponding rotation of said copy roll by movement of said web along said path in either direction, said web and copy roll being adapted to receive a composite therebetween on the periphery of said copy roll, means biasing said storage roll in a direction tending to wind said web thereon, and releasable drive means operatively associated with said take-up roll for rotating the latter in a direction to withdraw a portion of said web from said storage roll and advance the same along said prescribed path against the bias of said biasing means from an initial toward a second position to thereby rotate said copy roll in a composite-advancing direction, said drive means including release means operable in response to operation of said drive means sufficient to advance said web to said second position to release said take-up roll and thereby permit rewinding of said Web on said storage roll under the bias of said biasing means for return of said web along said path toward its initial position.

8. Apparatus for reproducing graphic originals comprising means defining a copy station, and means for conveying a composite of a graphic original and a copy sheet to and from said copy station, comprising a storage roll, a take-up roll, a web having one end portion wound on said storage roll and the opposite end wound on said take-up roll, guiding means defining a prescribed path for said web between said rolls and including a copy roll at said copy station over which said web is trained in continuous frictional engagement etfecting corresponding rotation of said copy roll by movement of said web along said path in either direction, said web and copy roll being adapted to receive a composite therebctween on the periphery of said copy roll, means biasing said storage roll in a direction tending to wind said web thereon, releasable drive means operatively associataed with said take-up roll for rotating the latter in a direction to withdraw a portion of said web from said storage roll and advance the same along said prescribed path against the bias of said biasing means from an initial toward a second position to thereby rotate said copy roll in a compos'ite-advancing direction, said drive means including release means operable in response to operation of said drive means suflicient to advance said web to said second position to release said take-up roll and thereby permit rewinding of said web on said storage roll under the bias of said biasing means for return of said web along said path to its initial position, and brake means operatively associated with said take-up roll for retarding the return movement of said web.

9. Apparatus for reproducing graphic originals comprising means defining a copy station, and means for conveying a composite of a graphic original and a copy sheet to and from said copy station, comprising a storage roll, a take-up roll, a web having one end portion wound on said storage roll and the opposite end wound on said take-up roll, guiding means defining a prescribed path for said web between said rolls and including a copy roll at said copy station over which said web is trained in continuous frictional engagement effecting corresponding rotation of said copy roll by movement of said web along said path in either direction, said web and copy rol-l being adapted to receive a composite therebetween on the periphery of said copy roll, means bias ing said storage roll in a direction tending to wind said web thereon, and drive means including escapement type gearing operatively associated with said take-up roll for rotating the latter in a direction to withdraw a portion of said web from said storage roll and advance the same along said prescribed path against the bias of said biasing means from an initial toward a second position to thereby rotate said copy roll in a composite-advancing direction, the escapement of said gearing being arranged to disengage said drive means from said take-up roll in response to rotation of said take-up roll sutficient to advance said web to said second position, thereby permitting reversal of said take-up roll and rewinding of said web on said storage roll under the bias of said biasing means for return of said web along said path to its initial position.

10. Apparatus for reproducing graphic originals comprising means defining a copy station, and means for conveying a composite of a graphic original and a copy sheet to and from said copy station, comprising a storage roll, a take-up roll, a web having one end portion wound on said storage roll and the opposite end wound on said take-up roll, guiding means defining a prescribed path for said web between said rolls and including a copy roll at said copy station over which said web is trained in continuous frictional engagement effecting corresponding rotation of said copy roll by movement of said web along said path in either direction, said web and copy roll being adapted to receive a composite therebetween on the periphery of said copy roll, means biasing said storage roll in a direction tending to wind said web thereon, drive means including escapement type gearing operatively associated with said take-up roll for rotating the latter in a direction to withdraw a portion of said web from said storage roll and advance the same along said prescribed path against the bias of said biasing means from an initial toward a second position to thereby rotate said copy roll in a composite-advancing direction, the escapement of said gearing being arranged to disengage said drive means from said take-up roll in response to rotation of said take-up roll sufficient to advance said web to said secondposition, thereby permit- 10 ting reversal of said take-up roll and rewinding of said web on said storage roll under the bias of said biasing means for return of said web along said path to its initial position, and brake means operatively associated with said take-up roll for retarding rotation thereof in said reverse direction and thereby retarding the return movement of said web.

References Cited in the file of this patent UNITED STATES PATENTS 519,390 Rawdon May 8, 1894 854,703 Rankin May 21, 1907 871,412 Johnston Nov. 19, 1907 1,535,784 Koerner Apr. 28, 1925 2,028,813 Stuart Jan. 28, 1936 2,411,335 Prezioso Nov. 19, 1946 2,522,033 Graham Sept. 12, 1950