US2951442A

US2951442A - Printing machines

Info

Publication number: US2951442A
Application number: US645798A
Authority: US
Inventors: Charles H Schwebel
Original assignee: Multigraphics Inc
Current assignee: AB Dick Co
Priority date: 1957-03-13
Filing date: 1957-03-13
Publication date: 1960-09-06
Anticipated expiration: 1977-09-06

Description

Sept. 6, 1960 c H. SCHWEBEL PRINTING MACHINES 3 Sheets-Sheet 1 Filed March 13, 1957 m lwm mm n r In. O max s mm P aw m a 5 Sept. 6,. 1960 c. H. SCHWEBEL 2,951,442

PRINTING MACHINES Filed March 15, 1957 5 Sheets-Sheet 2 Inventor Charges H. Schwebel Zfzfm Moi, W

' :R-Hornagfi P 1950 c. H. SCHWEBEL 2,951,442

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22%.; MM Imlent Charles H.5chweBe i56f i) J52, M W I vq+iorne s United States Patent 2,951,442 PRINTING MACHINES Charles H. Schwebel, Euclid, Ohio, assignor to Addressagraph-Multigraph Corporation, Cleveland, Ohio, a corporation of Delaware Filed Mar. 13, 1957, see. No. 645,798 '6 Claims. (Cl.101149.5)

This invention relates to printing machines and to printing methods. More specifically, the invention relates to a method and apparatus for transfer printing, by heat and pressure, from a master to a copy sheet.

In the printing arts, it is often desirable to print a number of images from a single master sheet or strip. For example, mailing strips or the like including a plurality of individual addresses representative of a mailing list are sometimes utilized for a series of diflerent mailing operations. Preparation of a complete mailing strip for each mailing operation is highly undesirable from an 2,951,442 Patented Sept. 6, 1960 inc mailing operations without requiring preparation of a completely new master strip.

A principal object of the invention, therefore, is a new and improved method of heat-and-pressure transfer print ing but which affords a substantially greater number of usable copies than can be obtained with previously known processes of this kind.

A further important object of the invention is a new and improved transfer printing machine for imprinting a copy sheet with image data from a master strip by a heat-and-pressure transfer process which effectively prohad to a master mailing strip upon which the individual addresses are formed as mirror or reverse images and from which the individual addresses are duplicated or transferred onto copy sheets which may comprise either independent mailing strips or the material to be mailed. Such transfer printing operations are commonly used in the mailing of magazines, periodicals of various types, premium notices, and the like. A printing machine of this kind is described and claimed in Patent No. 2,740,- 354 to John H. Gruver, issued April 3, 1956 on an application filed July 22, 1950; that particular machine utilizes a master strip bearing image data which may be transferred to a copy sheet or copy sheets either by lithographic or hectographic techniques.

Another transfer printing machine suitable for addressing and similar applications is described and claimed in a co-pending application of John H. Gruver, Ser. No. 480,032, filed January 5, 1955; now Patent No. 2,844,094, issued July 22, 1958, in the printing machine described in that application, transfer printing is effected by positioning a copy sheet at a printing station and pressing a master strip bearing an image to be transferred against the copy sheet. In this instance, however, lithographic, hectographic, and similar duplication processes are not employed; rather, the image on the master is transferred to the copy sheet solely by the simultaneous action of heat and pressure. The machine of the Gruver application utilizes a heated platen in conjunction with a master strip comprising a relatively thin porous carrier bearing an image formed from thenno-softening ink.

For many applications, the heat-and-pressure transfer technique and apparatus described in the aforementioned Gruver application affords substantial advantages as compared with transfer printing arrangements utilizing lithographic, hectographic or other more conventional image transfer procedures. For some applications, how ever, it is desirable to obtain a greater number of images or impressions from a single master strip than can be realized with the Gruver machine. In most instances, it is not possible to obtain more than five acceptable copies from the master strip ina machine utilizing the heat and pressure technique set forth in the aforementioned application, whereas, particularly in the preparation of mailing lists and the like, it may be desirable to utilize a single master address Strip, for as many as eight or ten longs the useful life of the master strip and permits utilization of a single strip in printing a relatively large number of copies.

Another object of the invention is a method and apparatus for heat-and-pressure transfer printing which substantially increases the number of copies which may be realized from a single master image without requiring a substantial increase in the cost of the printing equipment.

A corollary object of the invention is a method and apparatus for heat-and-pressure transfer printing which materially improves the quality of the printed image, particularly on prints made after the master image has been utilized a number of times.

Another important object of the invention is a method and apparatus for increasing the number of copies which may be obtained in a heat-and-pressure transfer printing process with a minimum of maintenance cost and without requiring the use of expensive operating supplies.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying'drawings which, by way of illustration, show preferred embodiments of the present invention and the principles thereof and what I now consider to be the best mode in which I have contemplated applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may'be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

Fig. l is a front elevation view of the printing station and associated elements of a transfer printing machine constructed in accordance with one embodiment of the present invention, a part of the machine having been broken away;

Fig. 2 is a detail perspective view taken at the forward right-hand corner of the printing machine shown in Fig. 1;

Fig. 3 is a plan view of a portion of the printing machine of Figs. 1 and 2 showing certain of the details thereof;

Fig. 4 is a sectional view taken along line 4-4 in' Fig. 3;

Fig. 5 is a front elevation view, similar to the righthand portion of Fig. l, of a printing machine constructed in accordance with another embodiment of the invention; Fig. 6 is a plan view of a part of the printing machine of Fig. 5 taken along line 6-6 therein; s

Fig. 7 is an enlarged detail view showing a coupling device utilized in the moistening apparatus of Fig. 6;

Fig. 8 shows the coupling device in an alternate position; and

Fig. 9 is a simplified schematic diagram of a control circuit for the apparatus of Fig. 6..

The transfer printing machineltl shown in Fig. 1 comprises a printing head 11 which is utilized to suspend a claimed in the aforementioned Gruver application; acoordingly, only a relatively brief description of the platen and anvil construction is included herein.

A pair of

spacer blocks

14 and 15 are mounted upon the undersurface of printing head 11 and are utilized to support a horizontal mounting plate 16 in fixed spaced relation to the printing head. Mounting plate 16, in turn, supports the platen 12, a pair of suspension springs 17 and 18 being utilized for this purpose and being connected between the mounting plate 16 and a leveling plate 19 which forms a part of the platen. The platen 12 further includes a base plate 20 which is separated from the leveling plate 19 by an asbestos or other insulating pad 21; The base plate 20 and pad '21 are mounted upon the leveling plate 19 by means of a mounting bolt 22 which passes through a mounting block 23 afiixed to leveling plate 19 and is threaded into the base plate 20.

The printing station structure in the embodiment of Fig. 1 further includes a pair of hollow bushings 25 and 26 which are anchored at their lower ends to the leveling plate 19. A pair of fixed guide pins 27 and 28 are disposed within bushings 25 and 26 respectively; the guide pins are afiixed at their upper ends to the mounting plate 16 and thus serve to guide the platen 12 for vertical movement with respect to the mounting plate 16. A vertical stop pin 30 is affixed to the mounting plate 16 and extends downwardly toward the platen 12 in a position to engage an adjustable stop member 31 which is afiixed :to theplaten 12.

' The printing station of printing machine 19 further includes means for guiding a master image strip 33 therethrough.' This master strip guide comprises a frame 35 having a central opening 36 therein which conforms in dimensions to the individual image areas on the master strip 33. Frame 35 is mounted upon a pair of

guide fingers

37 and 38 which in turn are supported from a pivotally mounted mounting block 40. A further pair of guide -fingers 41 and 42 are afiixed to the

fingers

37 and 38 respectively and are utilized in conjunction with

fingers

37 and 38 to guide the movement of the master strip 33 through the printing station. Mounting block is yieldably connected to the platen 12 for vertical movement therewith, the connection between these elements not being shown in the drawings. The frame 35 is normally maintained in spaced relation to the platen by means comprising an adjustable stop pin 45 which is afiixed to and extends downwardly from an arm 46 being attached to a portion of the printing machine frame. An angled spring plate 47 is attached to the pivotally movable mounting block 40 at one side thereof just above the

guide fingers

37 and 41. This angled plate 47 has one arm 47A which engages the lower end of an adjustable screw 49 which extends downwardly from a plate 50 attached to the forward corner of the platen leveling plate 19.

.Printing machine 10 further includes a supply spindle 52 upon which the supply reel 53 for the master strip 33 is mounted. From the supply reel 53, the master strip is directed around an idler roller 54 and over a second idler 55 to engage a diabolo roller 56, the diabolo roller being supported at the end of an arm 57 which is pivotal 1y mounted upon the frame of the printing machine as indicated at 58. From the diabolo roller 56, the master strip is directed around a feed spindle 60 and over a guide roller 61, through the aperture between fingers 37 and'41, across the opening 36 in the frame 35 of the printing station, and out through the slot between fingers 38 and 42. From the printing station, the master strip 33 extends over a guide roller 62 into engagement with a second feed spindle 63 and then into engagement with a second diabolo roller 64. From the diabolo roller 64, the master strip is directed over a further guide roller 65 to a rewinding or supply-reel 66. e

In order to Ieacha full understandiugof the operation of the transfer printing machine 10, it is necessary to consider the nature of the master strip 33. The image master 33 comprises a relatively thin porous carrier, usually a relatively inexpensive grade of paper. The addresses or other image data which are to be reproduced are imprinted upon this carrier with a thermo-softening ink; a preferred form of thermo-softening ink suitable for heat-and-pressure transfer printing is described in the co-pending application of John H. Gruver, Ser. No. 480,070, filed January 5, 1955, now abandoned. The ink described in that application comprises, in its preferred form, a mixture of gilsonite, a wax selected from the group consisting of carnauba wax, parafiin, and beeswax, and a non-drying liquid selected from the group consisting of castor oil, mineral oil, and oleic acid. An ink of this general type afiords excellent impressions, for a limited number of copies, in a flat platen machine of the kind described hereinabove when the platen temperature is of the order 015300 F.

Operation of the printing machine 10, as thus far described, is essentially similar to that of the printing apparatus described in the aforementioned Gruver application Ser. No. 480,032. Thus, a strip of copy sheets 70 which are to be imprinted with the image data from the master strip 33 are advanced step-wise through the machine in the direction indicated in Fig. 2 by the arrow A to locate the copy sheets successively in printing position above the anvil or impression plate '13 and beneath the aperture 36 in the frame 35. At the same time, the master strip 33 is advanced step-wise through the printing position beneath platen 20 and in registry with the aperture 36. The master strip feeding arrangement is maintained in registry with the means utilized for feeding the copy through the printing station so that as each copy sheet is positioned on the impression pad 13 the image carried by the master 33 next subsequent to the last one printed is positioned over the new copy sheet. A synchronized dual-feed arrangement suitable for use in the printing machine 10 is described in detail in the aforementioned Gruver Patent No. 2,740,354; inasmuch as the means selected for this portion of the printing machine are not critical to the present invention, the driving arrangement has not been illustrated in the drawings.

The platen base plate 20 is maintained at an elevated temperature, preferably by heating elements embedded in the base plate 20 thereof (not shown); a suitable thermostatic control arrangement may be provided for the platen heaters. Each time a new address on the master strip 33 is positioned over a new copy sheet in the strip 70, the printing machine is actuated to impel platen 12 downwardly with respect to the mounting plate 16; a suitable drive linkage is illustrated in the above-noted Gruver application, Ser. No. 480,032.

As the platen20 starts its downward movement, the mounting block 40 is pivoted, moving the frame 35 and the portion of the master strip 33 in the printing position toward the copy sheet 70 and impression plate 13. When the master sheet 33 engages the copy sheet 70, it can no longer move downwardly; the continued downward movement of the platen 12 brings the base plate 20' into engagement with the reverse or upper surface 71 of the master strip and presses the master against the copy sheet. At the same time, heat from the heated platen base plate 20 softens the ink on the lower or obverse face 72 of the master strip and deposits 3. portion of the ink on the copy sheet, thereby transferring some of the ink to the copy sheet. Subsequently, the platen 12 is returned to its normal or retracted position as illustrated in Figs. 1 and 2 and the master strip 33 and copy sheet strip 70 are both advanced to bring a subsequent address into-registry with the next copy sheet. The process is then repeated to transfer the next address or other portion of image data to the subsequent copy sheet.

.In the transfer printingmcthod set-forth in the two above-identified Gruver applications, heat and pressure alone are utilized to transfer the thermo-softening ink from the master strip 33 to the desired portion of the copy sheet strip 70. In the transfer printing method of the present invention, these factors are also of paramount importance in the transfer of the image to the copy sheet. In accordance with the present invention, however, the reverse or uninked surface 71 of the master strip 33 is moistened before the transfer impression is made. For this purpose, a liquid reservoir 75 is incorporated in the printing machine 10, being mounted upon a bracket 76 aflixed to the frame of the machine. As best shown in Figs. 2-4, the liquid reservoir 75 has an outlet 77 which connects the reservoir to a moistening pad 78 which is also supported from the bracket 76. Pad 78 may be fabricated from felt, sponge, or other suitable material capable of retaining and transferring liquid to the reverse surface 71 of the master strip without depositing undue quantities of liquid thereon and without leaking the liquid onto the machine parts.

As indicated in the drawings, the pad 78 is aligned with the master strip 33 as the latter extends between guide roller 61 and the guide slot between

fingers

37 and 41; as indicated in each of Figs. 1-4, the pad 78 is in contact with the reverse surface 71 of strip 33 whenever the master strip is under tension and is being moved through the printing machine. Whenever movement of the master strip is arrested, however, the accompanying reduction in tension on the master strip permits the master strip to sag to the position indicated by the phantom outlines 33A in Figs. 1, 2 and 4. Consequently, whenever the master strip 33 is not being pulled through the printing machine, it does not remain in contact with the moistening pad 78. This feature of the mounting arrangement for the moistening device comprising reservoir 75 and the moistening pad 78 is highly desirable in carrying out the inventive method, since otherwise the master strip might well become saturated with the moistening liquid or might at least become wet enough that it would tend to tear or break when tension was again applied thereto to continue movement through the machine.

Any one of a number of different moistening agents may be employed in carrying out the inventive method, since it is not a hectographic or lithographic process and does not require that the moistening liquid react in any manner with the thermo-softening ink comprising the image to be transferred to and imprinted upon the strip of copy sheets 70. The intrinsic effect of the moistening liquid, insofar as the master image on the strip 33 is concerned, is not known; it is known, however, that the moistening of the reverse surface of the strip 33 permits utilization of the master strip to produce a far greater number of copies than is possible in the dry heat-and-pressure arrangement set forth in the above identified Gruver applications. As of the present time, a number of different moistening agents have been tried and all have given approximately equivalent performance. For example, water, ethyl alcohol, and carbon tetrachloride have all been tried with equal success in conjunction with an image master using an ink of the kind described in the aforementioned Gruver application, Ser. No. 480,070.- These highly diverse moisten- .ing agents make it possible to utilize the master strip to obtain approximately twice as many impressions as the same master strip affords when utilized in a dry heatand-pressure transfer process. It is thus apparent that no chemical action as such is involved.

Moreover, it is by no means necessary or even desirable that the liquid employed be a solvent for the ink on the master strip. Indeed, the very reverse appears to be true, since the preferred thermo-softening ink is insoluble in water, alcohol, and carbon tetrachloride. It is possible that the liquid, when subjected to the heat utilized as the moistening agent.

from the heated platen 12 and vaporized thereby, fund tions as an emulsifying agent for the thermo-softening ink, although this is by no means certain. Another possible theory is that the moistening agent, once having been .volatilized, performs some catalytic action in aiding the softening of the ink, although this is perhaps questionable in view of the diverse nature of the liquids which have been found to be-efficacious in carrying out the inventive method. In any event, the effect achieved is similar to one of catalysis in that neither the ink nor the moistening liquid is apparently changed in chemical form to any extent in the printing process. Indeed, the improved results achieved with the method of the invention may be purely mechanical in nature; the steam or other vapor, in penetrating the pores of the paper strip normally used as a carrier for the thermo-softening ink, may in effect simply add to the total pressure applied to the ink and thereby enable the reproduction of usable images with a strip which has otherwise lost its useful ness.

From an economic standpoint, the method of the invention presents the greatest advantage when water is This is easily understandable in view of the price difierential between water and virtually any other liquid which might be employed for this purpose. Moreover, it is equally important to note that the inventive method may be carried out completely by a conventional heat-and-pressure transfer printer with only the addition of the extremely simple and inexpensive moistening device comprising reservoir 75, bracket 76, and moistening pad 78.

Figs. 5-9 illustrate another embodiment of the invention which in many respects is essentially similar to the printing machine 10 described hereinabove in connection with Figs. 14. Thus, the portion of the printing machine illustrated in Fig. 5 includes a printing head 11 which is utilized to support a vertically movable heated platen 12 at the printing station of the machine. and printing head structure may be essentially similar to that described in connection with Fig. 1 and may include the mounting plate 16 suspended from the printing head 11 as indicated at 14, the platen 12 being vertically movably supported beneath the mounting plate. As before, the platen may comprise a heated base member 20 suspended from the leveling plate 19 and separated therefrom by the insulating layer 21. The same mounting arrangement comprising the mounting block 23 may be utilized in this embodiment, along with the vertical guide 26 and the return spring 18.

The feeding system for the master strip 33 may be essentially similar to that shown in the first-described embodiment; the web 33 is guided over the

rollers

54 and 55 and over the diabolo roller 56 into engagement with the feed spindle 60; the diabolo roller 56, as before, may be supported upon a support member 57 pivotally mounted on the frame of the machine as indicated at 58. As it leaves the feed spindle 60, the master strip 33 is guided between the

guide fingers

37 and 41 into the printing station of the machine. The remaining unillustrated portion of the printing machine 100 may be essentially similar to the corresponding portion of the printing machine 10 shown in Fig. 1.

Printing machine 100, however, includes a moistening device 101 which is in some respects substantially different from that of the previously described embodiment. The moistening device 101, as. shown in Figs. 5 and 6, comprises a support bracket 102 which is affixecl to the frameof the printing machine and which extends upwardly therefrom to a location adjacent the portion of the master strip 33 intermediate roller 55 and diabolo roller 56. liquid reservoir 104 is mounted at the upper end of the bracket 102 and is provided with an outlet 105 which connects the reservoir to a moistening pad 106; the reservoir 104, outlet 105 and moistening pad 106 maybe essentially similar in-construction to the reservoir 75,

The platen outlet 77, and moistening pad 78 of the first-described embodiment.

. In this instance, however, the moistening pad 106 is not supported in a fixed position with respect to the master strip 33. Rather, pad 106 is mounted upon a support member 107 which is pivotally supported upon a transverse extension 108 of the bracket 102. This mounting arrangement, which is best shown in Fig. 6, permits movement of the support member 107 and the moistening pad 106 between the operative position shown in solid lines in Fig. 6 and the inactive position indicated by the dash outlines 106A-and 167A therein.

The transverse extension 108 of bracket 102 is also utilized to support a solenoid 110 and a coupling device 111; the coupling device is utilized to connect the solenoid tothe upper portion 112 of the-moistening pad support member 1137. The coupling device'111, which is shown in detail in Figs. 6-8, includes a U-shaped bracket 113 which is afiixed to the transverse portion 108 of the principal mounting bracket 102. A double notched cam 115 is included in the coupling device 111 and is joumaled upon a post 114 afiixed to the bracket 113. The coupling device further includes a-transverse coupling link 116 which extends across the bracket 113 through suitable apertures in the end portions or legs of the bracket. Coupling link 116 is connected at one end to the upper extension 112 of the moistening pad support member 107 and the other end of the coupling link is suitably connected to the shaft or plunger of the solenoid 110. This arrangement is best shown in Figs. 7 and 8. The coupling link 116 further includes a pair of downwardly extending

dogs

118 and 119; as indicated in Figs. 7 and 8, dog 118 extends substantially parallel to the axis of movement 129 of the coupling device, whereas dog 119 is oriented at an acute angle with respect to the axis 120. Figs. 7 and 8 also illustrate the configuration of the cam 115, which is provided with a pair of

notches

123 and 124 at the opposite ends thereof.

When the solenoid 110 is energized, the plunger 117 is driven in the direction indicated in Fig. 7 by the arrow A against the biasing force provided by a spring 125. This movement of the solenoid plunger drives the coupling link 116 in the same direction and brings the dog 119 into engagement with one surface 127 of the cam 115, rotating the cam counterclockwise through a minor arc to the position illustrated in Fig. 8. When the solenoid 110 is subsequently de-energized, the plunger 117 and connecting link 116 move in the direction opposite arrow A in response to the biasing force erected by the spring 125. Upon this return movement, the dog 113 engages a second surface 128 of the cam 115 and arrests the movement of the coupling link 116 in the position illustrated in Fig. 8. In this position, with the coupling link 116 extending farther to the left from bracket 113 (as seen in Figs. 68) than its original location, the moistening pad support member 167 is established in its operating or actuated position in contact with the uninked or reverse surface of the master strip 33.

The coupling device 111 and the moistening pad 166 remain in the actuated or operative position shown in Figs. 6 and 8 until the solenoid 111 is energized a second time. When this is done, the solenoid again drives the plunger 117 and the coupling link 116 in the direction of arrow A. The dog 119 engages another surfiace 130 of the cam 115 and rotates the cam to a position approximately perpendicular to the center line 120 of the coupling device. Subsequently, when solenoid 110 is deenergized and the plunger 117 and coupling link 116 begin their return movement in the direction opposite arrow A, the dog 118 engages the surface 131 of cam 115 and returns it to the position shown'inFig. 7, except that the cam 115 has now been rotated through an arc of 180. Thus, the'coupling device 111 establishes. a predetermined actuationsequence for the movement ofrnois- T tening pad 106 between its operative or actuated position and its normal or unactuated position, the latter being indicated by the dash outline 106A in Fig. 6.

Fig. 9 illustrates, in an extremely simplified form, a control circuit for the solenoid 110. In this figure, the solenoid operating coil is illustrated by the inductance A, one end of which is connected to one terminal of a power supply. The other end of the coil 110A is returned to the power supply through a pair of switches 135 and 1 36 which are connected in parallel with each other. Switch 135 is mechanically or electrically coupled to the starting switch of the printing machine, whereas switch 136 is suitably coupled to the stop switch of the printing machine.

In operation, the printing machine 190 shown in Figs. 59 is in most respects similar to the previously described embodiment. At the outset, it may be assumed that the coupling device 111 is in its unactuated or normal position as shown in Fig. 7 and maintains the moistening device 1196 in its inactive position as indicated in Fig. 6 by the dash outline 106A. Thus, when the starting switch of the printing machine is closed, switch 135 (see Fig. 9) is also closed and energizes the operating coil 110A of solenoid 111). Energization of the solenoid actuates the coupling device 111 to its second or actuated position as shown in Fig. 8 and consequent- 1y pivots the support member 197 to bring the moistening pad 106 into contact with the uninked or reverse surface of the master strip 33. When the operator of the printing machine releases the starting switch, the coil 110A is de-energized, since switch 135 returns to its normal or open position. As indicated hereinabove, however, the coupling device 111 does not return to its initial position as shown in Fig. 7 but remains in the actuated position of Fig. 8 so that the master strip 33 is continuously moistened as it moves through the printing machine.

Subsequently, whenever the operator finds it necessary or desirable to stop the operation of the printing machine, the stop switch of the machine is actuated and, consequently, the switch 136 is closed, again energizing solenoid coil 116A. This second energization of the solenoid and subsequent opening of switch 136 when the stop switch of the machine is released returns the coupling mechanism 111 to its initial position (see Fig. 7) and, accordingly, returns the moistening pad 106 to its initial position 1116A out of contact with the master strip 3 3.

It is thus apparent that the printing machine shown in Figs. 5 9 efiectively carries out the inventive transfer printing method by moistcning the reverse surface of the master 33 before the thermo-softening inkimage on the master is transferred to a copy sheet. As in the previously described embodiment of the invention, it

i is preferred that the moistening liquid utilized be water in view of the obvious economic advantages thereof. The printing machine 1% further avoids excess moistening of the master strip by maintaining the moistening device out of contact with the master strip whenever the. machine is shut down. Moreover, this objective is accomplished without requiring continuous energization of any electrical operating device such as the solenoid 110, which is enengized only at the times that the machine is started and stopped.

it will be obvious to those skilled in the art that the apparatus embodiments of Figs. 1-4 and of Figs. 5 -9 represent only two of many possible -means for carrying out the inventive method, although they afford substantial advantages as compared with other apparatus arrangements. Moreover, the method itself may be accomplished completely and effectively by hand in a relatively low-speed transfer printing procedure. Whether carried out by hand or by either of the two preferred apparatus embodiments of the invention illustrated .and described herein by any other suitable means, the

transfer printing method of the invention affords substantially greater numbers of copies, in a transfer printing process using a thermo-softening ink and heat-andpressure transfer, than can be obtained with previously known techniques. Consequently, the useful life of the master strip or other master image member is considerably prolonged. The apparatus embodiments of the invention are quite inexpensive with respect to the additional equipment required for the printing machines; both of the apparatus embodiments afiord substantial advantages in that they effectively minimize maintenance cost. In this respect the apparatus embodiment of Figs. 1-4 is preferable in that it entails utilization of somewhat simpler equipment that the positively-actuated arrangement of Figs. 5-9, although the latter may be preferable in some applications.

Hence, while I have illustrated and described the preferred embodiments of my invention, it is to be understood that these are capable of variation and modification, and I therefore do not Wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

1. A transfer printing method for imprinting a copy sheet with image data from a master comprising a relatively thin porous carrier having a thermo-softening ink image deposited on a given surface thereof, said transfer printing method comprising the following steps: moistening the reverse surface of the master; bringing the master and the copy sheet into pressure contact with each other, the image-bearing surface of the master being in contact with the image-receiving surface of the copy sheet; and heating the moistened master while in pressure contact with the copy sheet to soften the ink and deposit a portion thereof upon the copy sheet.

2. A transfer prin' g method for imprinting a copy sheet with image data from a master comprising a relatively thin porous carrier having a thermo-softening ink image deposited on a given surface thereof, said transfer printing method comprising the following steps: moistening the reverse surface of the master with a volatilizable liquid in which the ink is insoluble; bringing the master and the copy sheet into pressure contact with each other, the image-bearing surface of the master being in contact with the image-receiving surface of the copy sheet; and heating the moistened master while in pressure contact with the copy sheet to volatilize the moistening liquid and to soften the ink, thereby depositing a portion of the ink upon the copy sheet.

3. A transfer printing method for imprinting a copy sheet with image data from a master comprising a relatively thin porous carrier having a thermo-softening water-insoluble ink image deposited on a given surface thereof, said transfer printing method comprising the following steps: moistening the reverse surface of the master with water; bringing the master and the copy sheet into pressure contact with each other, the imagebearing surface of the master being in contact with the 10 image-receiving surface of the copy sheet; and heating the moistened master while in pressure contact with the copy sheet to vaporize the Water and to soften the ink, thereby depositing a portion of the ink upon the copy sheet.

4. A transfer printing method for imprinting each of a plurality of copy sheets with image data from a single master comprising a relatively thin porous carrier having a thermo-softening ink image deposited on a given surface thereof, said transfer printing method comprising the following steps: moistening the reverse surface of the master; bringing the master and the individual copy sheets successively into pressure contact with each other, the imagebearing surface of the master in each instance being in contact with the image-receiving surface of the copy sheet; and heating the moistened master, while in pressure contact with each copy sheet, to soften the ink and deposit a portion thereof upon each copy sheet.

5. A transfer printing method for imprinting each of a plurality of copy sheets with image data from a single master comprising a relatively thin porous carrier having a thermo-softening ink image deposited on a given surface thereof, said transfer printing method comprising the following steps: moistening the reverse surface of the master; bringing the master and one copy sheet into pressure contact with each other, the imagebearing surface of the master being in contact with the image-receiving surface of the copy sheet; heating the moistened master while in pressure contact with the copy sheet to soften the ink and deposit a portion thereof upon the copy sheet; and repeating the recited steps with each copy sheet to imprint the image thereon.

6. A transfer printing method for imprinting each of a plurality of copy sheets with image data from a single master comprising a relatively thin porous carrier having a thermo-softening ink image deposited on a given surface thereof, said transfer printing method comprising the following steps: moistening the reverse surface of the master; bringing the master and one copy sheet into pressure contact with each other, the image-bearing surface of the master being in contact with the image-receiving surface of the copy sheet; heating the moistened master while in pressure contact with the copy sheet to soften the ink and deposit a portion thereof upon the copy sheet; and repeating only the last two steps with succeeding copy sheets to imprint the image thereon.

References Cited in the file of this patent UNITED STATES PATENTS 1,049,741 Lichtenstein Jan. 7, 1913 1,281,781 Jean Oct. 15, 1918 2,057,696 Sherman Oct. 20, 1936 2,068,268 Francis Ian. 19, 1937 2,398,288 Collins Apr. 9, 1946 2,501,495 Carroll et a1 Mar. 21, 1950 2,503,185 Wright Apr. 4, 1950 2,740,354 Gruver Apr. 3, 1956