US2934007A - Duplicating machines - Google Patents

Description

ApriI'ZG, 1960 F. s. FRANCIS EIAL 2,93

DUPLICATING MACHINES Filed ma 2?, 195a 25/ A V 7 7 I \ATTORNEY United States atent I DUPLICATING MACHINES Frederick George Francis, Old Southgate, London, and Robert James Monlton, Cranham, England, assignors to Caribonurn Limited, London, England, a company of Great Britain Application May 27, 1958, Serial No. 738,141

Claims priority, application Great Britain May 29, 1957 2 Claims. (Cl. 101-131) The present invention relates to duplicating machines.

Duplicating systems or processes are known in which a reversed positive master sheet is prepared by the action of writing upon a sheet of paper superimposed upon a sheet of carbon paper with its transfer-coated side upwards. The master sheet is .then used for duplicating by wrapping it round a cylinder which contacts a pressure roller and feeding copy sheets between the cylinder and roller. In these duplicating systems, it is common practice for the carbon paper used for preparing the master sheet to be coated with a transfer composition which includes a high proportion of a dye or other colouring material which is soluble in water, methylated spirit or some other copying fluid and the duplicating machine is provided with arrangements for moistening the copy sheets with a suitable fluid as they are fed between the cylinder and the pressure roller, so that a portion of the dye on the reversed positive master sheet is dissolved and transferred to the copy sheets as an ordinary positive copy.

An improvement in duplicating systems of this known kind, which are cornrnonly referred to as spirit duplicating systems, is disclosed in the co-pending application Serial No. 719,704, filed March 7, 1958, of F. G. Francis and G. C. Phillpotts wherein the use of methylated spirit or other copying fluid is eliminated and the disadvantages attendant upon the use of sheets bearing quantities of highly coloured and soluble dyes are also avoided. Furthermore, with certain papers, methylated spirit may cause creasing or, if used in excess, can destroy the effective life of the master copy.

According to the invention disclosed in the aforesaid specification, a dry duplicating method comprises the steps of (1) providing a master sheet having thereon a substantially colourless reversed positive of written matter to be duplicated, the reversed positive comprising a colourless acid-sensitive dyestufi derivative, (2) subjecting the master sheet to pressure contact with a copy sheet carrying an acid fixing substance for forming and then fixing the dyestuii derivative to form an undeveloped copy of the written matter on the copy sheet and (3) thereafter exposing the copy sheet to a source of heat sufficient to cause substantially immediate colour-forming and colourfixing reactions between the colourless dyestuif derivative and the acid fixing substance, thereby to form a fixed, legible, developed, positive copy of the written matter upon the copy sheet. The colour-forming reaction can occur in about 1 to 2 seconds or even less, depending upon the intensity of the heating of the copy sheet.

Itis an object of the present invention to provide a duplicating machine for use in operating a duplicating system of the kind disclosed in the aforesaid application.

According to the present invention, a completely dry duplicating machine consists essentially of a rotatable cylinder, means for rotating the cylinder, means on the cylinderfor supporting a reversed positive master sheet in wrapped relationship about the rotatable cylinder for rotation therewith, the reversed positive master sheet com ice prising mirror-script written matter to be duplicated constituted by a pressure-transferable composition containing a colourless acid-sensitive dyestufi derivative, a pressure roller adjacent the rotatable cylinder, means for driving the pressure roller, copy sheet guide means forguiding copy sheets between the pressure roller and the rotatable cylinder, thereby to subject the copy sheets successively to pressure contact with the reversed positive master sheet, each copy sheet carrying on the surface thereof to be pressure contacted with the reversed positive master sheet a non-transferable coating containing an acid fixing substance capable of reacting with the dyestuff derivative at an elevated temperature to convert the dyestuff derivative into the dyestufi, the pressure contact of the copy sheets with the reversed positive master sheet serving to transfer some of the pressure-transferable composition from the master sheet to each successive copy sheet and also serving to advance each successive copy sheet away from the rotatable cylinder and the reversed positive master sheet, and a source of heat disposed beyond the rotatable cylinder in the direction of advance of the successive copy sheets for heating each copy sheet to an elevated temperature substantially immediately afterits pressure contact with the master sheet thereby to cause a colour-forming reaction to occur between the colourless acid-sensitive dyestuff derivative and the acid fixing substance to form a fixed, legible, developed, positive copy of the written matter upon each successive copy sheet in the absence of any means for moistening the copy sheets. I

In order that the invention may be readily understood, certain preferred embodiments are described below by way of example in conjunction with the accompanying drawing, in which:

Fig. 1 shows a diagrammatic sectional view of one form of dry duplicating machine;

Fig. 2 shows a diagrammatic sectional view of a second form of dry duplicating machine;

Fig. 2a shows a detail of Fig. 2 in side elevational view;

Fig. 3 shows a diagrammatic sectional view of a third formof dry duplicating machine.

Referring to Fig. l, the duplicating machine includes a rotatable cylinder 10 which is mounted for rotation, as by means of a crank handle or an electric motor (not shown), upon a horizontal shaft 11. The surface of the cylinder includes means for grip-ping one edge of a reversed positive master sheet, of the kind which carries a pressuretransferable coating comprising a colourless acid-sensitive dyestuii derivative, as described in the aforesaid application. These sheet-gripping means conveniently comprise a hinged or otherwise movable portion 12 of the cylinder surface, which portion 12 can be clamped down upon the edge of the master sheet, which is then wrapped around the surface of the cylinder 10 so as to be supported thereby, the opposite edge of the master sheet being left free or secured by suitable means (not shown) in a manner known per se, for instance, in conventional spirit-duplicating machines. The rotatable cylinder 10 lies above and in pressure contact with a rubber-covered or other resiliently-surfaced pressure roller 14, which is driven by the cylinder 10 on rotation of the latter and thereby serves to subject copy sheets to pressure contact with the master sheet, as the copy sheets are fed to the nip between the cylinder 16 and the roller 14. Due to the pressure and rotation of the cylinder 10, which causes the roller 14 to rotate, the copy sheets are fed towards a pair of rollers, indicated at 15 and 16. The roller 14, which is mounted upon a spindle 14a thus serves both to advance the copy sheet through the machine and to bring it into pressure contact with the reversed positive master sheet.

The roller 15 serves as a counterpressure roller for the heatable roller 16 and is drivingly coupled with the roller 14, as by means of a belt 33 further described'below. The roller 15 thus serves to support and advance the copy sheet in contact with the roller 16, which contacts the upper surfaceof the copy sheet, namely the surface which was pressed against the master sheet. The roller 16 is heated as by means of an internal electric heating coil indicated at 17 and the heat and pressure to which the copy sheet is then subjected are sufiicient to cause a colour-forming reaction to occur, as described'in more detail in the aforesaid prior application, In this embodiment of the invention, the source of heat, i.e. the heatable roller 16, raises the temperature of the copy sheet by conduction. r

The cylinder 10 and the rollers '14, and 16 are arranged in a suitable housing 18, which comprises a part enclosing the source of heat and a part'enclosing the rotatable cylinder and may include to this end a base portion 19, a hinged cover portion 20 over the cylinder 10 and a louvred cover portion 21 over the heating roller 16. The purpose of the louvres in the cover portion 21 is to assist in dissipating heat from the machine The hinged cover portion 20, comprising part of the housing'18 enclosing the cylinder 10, is provided so that it can be removed to give access as required'to'the cylinder 10, such as for removing or locating the master sheet thereon. The housing 18 is conveniently made generally symmetrical and includes two opposing side walls, one of which is indicated at 22, uponwhich the cylinder 14), the rollers 14, Hand 16 and other'parts of the machine are conveniently mounted. The machine may also include end walls 24 and 25 and the end wall 24 carries a feed platform 26 for directing'the copy sheet to the nip between the cylinder 10 and the roller 14, the platform 26 and the hinged cover portion 20 forming between them an inletslot 27 for the copy sheet adjacent the cylinder 14 A copy sheet support 28 is provided between the rollers 15 and 14, which are spaced so that the leading edge of the copy sheet reaches the nip between the rollers 15 and 16 as or before the trailing edge leaves the nip be: tween thecylinder 10 and the roller 14. A further guide or support platform 29 is provided for receiving the copy sheet and directing it to an outlet slot 3% provided in the end wall 25 and can lead to a platform 31 on to which the finished, i.e. developed, copy sheets are discharged and collected. A bafiie plate 32 may be provided above the sheet support 28 to divide the two main parts of the machine housing 18 from one another, to assist in directing hot air to the louvred cover portion 21 and, especially, 'to=prevent orat'least diminish the passage of heat from the heatable roller.16 to the master sheet. The pair of rollers 15 and 16 are driven in any suitable way, as by means of a driving belt 33 connecting the roller 15 to the roller 14 by means of belt pulleys 15a and 14b mounted on the ends thereof,

:as a set of tapes or an endless belt 41, and a super- :posed pressure roller 42, which rollers 40 and '42 feed the "copy sheet on to the upper run of the tapes or belt 41 towards a roller 44, forming the other turning point for the endless belt 41, and its superposed pressure roller'45, from where the copy sheet passes to the support platform 29 and the outlet slot 30. The pressure roller 42 is preferably made of india-rubber and its surface includes a plurality of pointed members, such as the projections 42a, for causing the paper to come into contact with the copy paper, while coming into contact as little as possible with the written matter, so as to avoid undeveloped matter offsetting on the roller 42.; A copy sheet support 28' is ,provided for guiding the copy sheet fromthe roller 14 to the conveyor tapes or belt 41, which is driven in anysuitnumber is not limiting).

able way, as by means of a driving belt or chain 46 connecting the roller 14 to the belt roller 40 in such a manner that the surface speed of the belt 41 is the same as that of the roller 14.

It is found convenient to arrange the resilientpressure roller 14 so that it can be moved toward-and away from the cylinder 10.- Suflicient freedom of movement of the roller 14 is provided such that it can be taken out ofcontact with the cylinder 10, when required. This permits the master copy to be wrapped round the cylinder 10 in a convenient way, after removal of the hinged'cover portion 20, as by turning the cylinder 10 without coming into contact with the roller 14. This is conveniently provided for, as shown in Fig. 2a, by mounting the spindle 14a on the roller 14 upon a lever 13 having a cam 13a integral therewith and acting upon the spindle 14a of the roller 14, so as to move the latter toward and away from the cylinder 10 as the lever 13 is pivoted. This arrangement also allows the pressure between the roller 14 and the cylinder 10 to be adjusted to suit the particular reversed positive master sheet being used;

In this embodiment, the source of heat for causing the colour-forming reaction to occur in the copy sheet while it is upon the endless belt 41 operates by radiation and is constituted by one or more 'infra-red'lamps or heaters, shown diagrammatically at 47. If desired, a radiant heating element 47a may additionally be located under the belt 41, so as to provide an additional efiect by convection and/or radiation. For greater efliciency, the infra-red lamps and/or heaters 47 may be focussed on the copy sheets, if desired. The heating apparatus may consist of infra-red tubular quartz lamps disposed transversely of the movement of the paper, preferably backed by reflectors. These lamps are conveniently associated with a controlling microswitch arranged so that the lamps are only energised when a copy sheet is passing through the machine.

A particularly useful type of heatergwhich may replace that shown in Fig. 2, is an open coiled wire heater, which is suitably fenced against contact. Eight coils extending across the machine are a suitable number (though this This has the advantage that the machine becomes rapidly heated to the desired operating temperature. With radiant heating of this kind and also with infra-red heating, it is convenient for the base upon which the paper is carried and also the inside upper surfaces of the housing cover to be covered with polished aluminum foil or sheeting or some other heat-reflecting surface, so as to intensify the heating efiect. It is also an advantage in this embodiment of the invention, to enclose the heater and the transporting surfaces for the copy sheets in a separate shield or cover lower than that shown in the drawing, so that a hot air atmosphere is created under the shield or lower cover through which the copy sheets must pass. e

In a further embodiment, the heating of the copy shee ts is effected by means of one or more jets of very hot air which are directed, as by means of a fan, ducts and heaters, on to the surface of the copy sheet as it passes through the machine. A suitable temperature for the air is from 200 to 350 C.

Referring now to Fig. 3, the cylinder 10 in this embodiment is mounted beneath its pressure roller, shown at 14', which is enclosed in a fixed portion 20'. of the housing 18' and the housing portion represented by the end wall, 7

shown at 24, is hinged to the base 19 or is otherwise removable to give the necessary access to the cylinder 10. As in the embodiment shown in Fig. 2, the copy sheet is supported upon an endless conveyorbelt 41 driven by means of rollers 40 and 44, which latter roller 44 may itself be driven from the cylinder 10 by a driving belt 46'. The source of heat for heating the copy sheet is provided ,by a hot plate 50 including a radiant electric heating element 51 and mounted above the endless belt 41 under the louvred portion 21 of the housing 12.

The mode of operation of the duplicating machine, in any of the embodiments described above, is as follows:

Access to the cylinder it? is obtained by opening the portion 20 or 20' (Fig. 3) of the housing 18 and the master sheet is secured to the cylinder 18 by means of securing arrangements comprising the movable portion 12. The heating means, e.g. the coil 17 (Fig. 1), the infra-red lamps 47 (Fig. 2), the additional heater 47a (Fig. 2) or the coil 51 (Fig. 3), are energised and the cylinder is rotated by hand or by operating an electric or other power drive. Copy sheets are fed to the inlet slot 27, preferably by means of some known form of sheet feeding mechanism, pass through the successive stages of pressure contact with the master sheet and heating, as previously described, and then emerge through the outlet slot 30 as clear, fully developed and lighbfast copies of the written matter to be duplicated.

It will be appreciated that the invention provides a relatively simple machine for duplicating which may be constructed in a variety of different forms and operation of which can merely involve energising the source of heat, wrapping the master sheet round the cylinder and rotating a crank handle to feed the acid-coated copy sheets from the inlet slot to the outlet slot. It will also be understood that the machine may be constructed so as to have a mechanical or electric drive and may be provided with driven sheet feeding arrangements.

We claim:

1. A completely dry duplicating machine, which comprises, in combination, a housing divided into a first part and a second part, but with communication between the first and second housing parts, a rotatable cylinder disposed in the first housing part, means for rotating the cylinder, sheet-gripping means on the cylinder for supporting a reversed positive master sheet in wrapped relationship around the surface of the rotatable cylinder for rotation therewith, the reversed positive master sheet comprising rnirror-script written matter to be duplicated constituted by a pressure-transferable coating containing a colourless acid-sensitive dyestufi derivative, a pressure roller disposed in the first housing part adjacent the rotatable cylinder, means disposed in the housing for driving the pressure roller, copy sheet guide means in the first housing part for guiding copy sheets between the pressure roller and the rotatable cylinder thereby to subject successive copy sheets to pressure contact with the reversed positive master sheet, each copy sheet carrying on the surface thereof to be pressure contacted with the reversed positive master sheet a non-transferable coating containing an acid fixing substance capable of reacting with the dyestufi derivative at an elevated temperature to convert the dyestufi derivative into the dyestufi, the pressure contact of the copy sheets with the reversed positive master sheet serving to transfer some of the pressuretransferable composition from the master sheet to each successive copy sheet and also serving to advance each successive copy sheet away from the rotatable cylinder and the reversed positive master sheet in the first housing part into the second housing part, a heatable roller disposed in the second housing part beyond the rotatable cylinder in the direction of advance of the successive copy sheets, means for heating the heatable roller, such roller thereby constituting a source of heat, another roller disposed in the second housing part adjacent to and pressure contactable with the heatable roller and copy sheet guide means disposed between the pressure roller in the first housing part and the heatable roller in the second housing part for guiding each successive copy sheet to and between the heatable roller and the roller adjacent thereto for subjecting each copy sheet to pressure and simultaneously heating such copy sheet to an elevated temperature substantially immediately after its pressure contact with the master sheet thereby to cause a colourforming reaction to occur on the copy sheet between the colourless acid-sensitive dyestufl derivative and the acid fixing substance to form a fixed, legible, developed, positive copy of the written matter upon each successive copy sheet without moistening the copy sheets.

2. A completely dry duplicating machine, which comprises, in combination, a housing, a baffle within the housing for dividing it into a first part and a second part while permitting communication between the first part and the second part, a rotatable cylinder disposed in the first housing part, means for rotating the cylinder, sheet-gripping means on the cylinder for securing a dry reversed positive master sheet in wrapped relationship around the surface of the rotatable cylinder, the first housing part being constructed in a removable manner so as to permit access to the cylinder for securing the master sheet to the rotatable cylinder, an inlet slot in the first housing part for introducing successive dry copy sheets thereinto, a pressure roller disposed in the housing adjacent the rotatable cylinder, means for driving the pressure roller, copy sheet'guide means disposed in the first housing part between the inlet slot and the rotatable cylinder for guiding the dry copy sheets from the inlet slot to and between the rotatable cylinder and the pressure roller thereby to subject each copy sheet to pressure contact with the reversed positive master sheet, the reversed positive master sheet comprising on the outer surface thereof mirror-script written matter to be duplicated in the dry state constituted by a pressure-transferable coating containing a colourless acid-sensitive dyestufi derivative and each copy sheet carrying on the surface to be contacted with the reversed positive master sheet a non-transferable coating containing an acid fixing substance adapted to react with the dyestuft derivative at an elevated temperature to convert the dyestuff derivative to the dyestufi, the pressure contact of the copy sheets with the master sheet serving to transfer some of the pressure-transferable composition from the master sheet to each successive copy sheet and also serving to advance each successive copy sheet away from the rotatable cylinder and the reversed positive master sheet in the first housing part and past the baffle and into the second housing part, at least one infra-red lamp constituting a source of heat disposed in the second housing part beyond the rotatable cylinder in the direction of advance of the copy sheets, heat-dissipating louvres provided within the second housing part for dissipating heat from the machine, copy sheet guide means for guiding the copy sheets from the rotatable cylinder and into the vicinity of the source of heat whereby each successive copy sheet is heated to an elevated temperature sufficient to cause a colour-forming reaction to occur on such copy sheet between the colourless acidsensitive dyestufl derivative pressure-transferred thereto with the pressure-transferable composition and the acid fixing substance contained in the non-transferable coating thereon substantially immediately after such pressure contact of each copy sheet with the master sheet, thereby to form a fixed, legible, developed, positive copy of the written matter upon each successive copy sheet while such copy sheets are maintained continuously dry, an outlet slot in the second housing part for the developed copy sheets, and copy sheet guide means disposed in the second housing part for guiding the developed copy sheets from the vicinity of the source of heat to the outlet slot.

References Cited in the file of this patent UNITED STATES PATENTS 632,619 Arm Sept. 5, 1899 1,281,780 Jean Oct. 15, 1918 1,281,781 Jean Oct. 15, 1918 2,112,849 Jones et a1. Apr. 5, 1938 2,389,848 Gibson et a1. Nov. 27, 1945 2,398,288 Collins Apr. 9, 1946 2,588,917 Geib Mar. 11, 1952 2,755,200 Balon et al. July 17, 1956 2,755,203 Stallman July 17, 1956

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