US3537377A - Developing device for document copying apparatus - Google Patents

Description

United States Patent Inventor Walter Limberger l-lamburg-Poppenbuttel, Germany 682,809 Nov. 14, 1967 Nov. 3, 1970 Lumoprint Zindler KG Hamburg, Germany May 11, 1967 Denmark Appl. No. Filed Patented Assignee Priority DEVELOPING DEVICE FOR DOCUMENT COPYING APPARATUS l l Clalms, 7 Drawing Figs.

US. Cl. 95/89, 156/5 5 1 Int. Cl 603d 3/00 Field of Search 95/89,

89/(M1SC), 89/(LAM); 156/551; ll8/(lnquired) References Cited UNITED'STATES PATENTS 9/1900 Deuther 8/1926 Norton 156/551X l56/551X 2,692,540 10/1954 Bing ..95/89(MISC)UX 3,165,998 1/1965 Reick 95/89(LAM)UX 3,301,156 1/1967 Roeber 9 5/89 3,354,807 11/1967 Homer 95/89X FOREIGN PATENTS 140,753 4/1951 Australia 95/89 102,014 6/1965 Denmark. 95/89(LAM)UX 847,846 6/1952 Germany.. 95/89(LAM)UX 856,846 9/1952 Germany 95/89(LAM)UX 921,742 3/1963 Great Britain... 95/89(LAM)UX 369,479 3/1939 ltaly 156/551 Primary Examiner-Norton Ansher Assistant Examiner-Monroe H. Hayes Attorney-McGlew & Toren ABSTRACT: In a developing device for the treatment of copying materials by means of the silver salt diffusion method two tanks are provided, one inside the other. An application roller is mounted inside the inner tank for cooperating with a squeezing roller for moistening the surface of the receiving material. A pair of squeezing and transport rollers are located downstream of the tanks and in the common path of the receiving material and the negative for pressing the two together.

Patent d Nov. 3, "1970 Sheet .2 f6

I N Q x25:

E J 2 h Inventor:

wi s unmask 3y Patented Nov. 3, 1970 Sheet 5 of 6 Fly. 6

Inventor:

W'Md W 87 HALTER LIMBERGER Patented Nov; 3, 1970 Sheet 6 of6 Inventor; 9 .WHLTER LIMBERGER WQM wwvH nw DEVELOPING DEVICE FOR DOCUMENT COPYING APPARATUS The invention relates, as indicated, to a silver salt diffusion method, using a negative material on the halide silver emulsion layer of which an image is exposed, and a receiving material to which the image is transferred, wherein the exposed negative material is wetted with a known liquid, causing it to be developed, and is subjected to a pressing in contact with the wetted receptor material of paper, film, or textile.

In the silver salt diffusion method, widely varying substances may be used as receptor carriers, for example, uncoated paper, textiles, wood, celluloid, other plastics, and the like. In this connection it should be stated that the term material, as used according to the invention, relates to foliate material.

It has also been proposed to support or enhance the transfer by the presence of substances favouring the diffusion. In this case, the diffusing or diffused silver halide can be developed pictorially without exposure, wherein this development is supported by added nuclei or reacting substances. Here, the developed picture is produced, for example, on a baryte paper or textile base, which has been wetted in the same bath as the silver halide material.

In the practical embodiment of this method, such as it has been commercially developed for use with foliate copying materials, a distinct positive or receptor layer has always been provided in which the reduction nuclei are contained. Generally, this layer is arranged on a special carrier so that the layer and the carrier form together the receptor material.

It is furthermore known, in an apparatus for producing positive images in accordance with the silver salt diffusion method, to expose the film carriers or bases, guided by guide elements, to the effects of a developing liquid and to press them together thereafter. in this case, channels passing through the developer may be formed for the one carrier while the other carrier, running above the developing liquid, passes to an applicator for applying the developing liquid, for example, to an application roller.

The invention has the object of providing an apparatus by means of which it is possible to produce, using two different baths, a picture in accordance with the silver salt diffusion method, wherein both film carriers are wetted with different liquids. Where the terms positive and negative" have been used hereinbefore, the negative is always provided with a silver halide layer, while the positive or receptor material can be an ordinary sheet.

It is another object of the invention to provide a copying apparatus with a new developing device, and comprising a particularly convenient form of control.

According to the invention, this object is realized in that the liquid application roller is arranged in a developing device, in a special closed tank with closed bottom and filled with a distinct liquid, and in that the applicationroller is associated with a spring-loaded contact pressure roller. which ensures, substantially simultaneously with the wetting, the distribution and penetration of the distinct liquid, wherein the wetting and pressing of the positive material is effected in one working step. Preferably, the liquid applicationroller is provided at the end of the special bath tank.

This solution is particularly advantageous, not only-because the receptor material or positive is delivered comparatively dry from the apparatus, which is knownper se, but also, particularly, because the distribution and the pressing causing the penetration intothe material iseffectedpractically in one step with the application of the liquid to the surfaceofthe positive. It is therefore an essential feature of the invention that the liquid application-roller is designed with a profiled roller surface, whichentrains the-liquid andthat, duringthe pressingby the contact pressure. roller, owing tothe projectionsforming part of the profiles, a concentration of the liquid: is effected during the dispersionand alsothe penetration thereof intothe surface of the receiving material.

This is an important'feature of the invention, because the utilization of the profiled projections results not only in the liquid being supplied, but also, in conjunction with a contact pressure roller, for distributing and pressing into the receiving material, resulting in a device which makes it possible to use, according to the invention, ordinary, that is to say uncoated, sheets of receiving material.

Conveniently and preferably, the application roller is flocked and hairy. According to another preferred embodiment, of the invention, the application roller is profiled and equipped with dot-like dished recesses. In conjunction with the above-mentioned embodiments, according to a further preferred embodiment of the invention, the contact pressure roller has a surface coating with a water-repellent material, such as the polytetrafluoroethylene marketed under the Trade Name Teflon", for example.

The developing bath for the photographic negative may be filled with a conventional known developer, while the positive or receiving material is wetted with a special liquid, having for example the following composition:

H O= Distilled water. Mirasol=5% solution in H O (wetting agent). Na S O solution=sodium thiosulphate, 1% in H O. AgNO solution 1% Silver nitrate solution in H O. Gold solution 1% gold (III) chloride hydrochloride yellow in H O.

Platinum solntion= 1% hexachloroplatic (IV) acid, dry

Example IV 1,000 ml. H 0.

15 ml. Mirasol.

10 ml. platinum solution. 5 ml. Na t O solution.

5 ml. gold solution.

Example V:

1,000 ml. H 0.

15 ml. Mirasol.

10 m1. platinum solution. 5 ml Na S O solution. 10 ml. glod solution.

This shows that the troughs must receive quite different liquids.

According to yet another'feature of the invention, the contact zones of the setsof rollers are arranged substantially at the same level. However, the arrangement may also be such that the connecting line between the axes of the downstream squeeze and transport roller pair forms an angle with the connecting line between the axes of the upstream squeeze and transport roller pair. In this way, aparticularly advantageous combination and removal slantingly upwardly may be achieved, whilethere is maintained a good connection to the guide elements in the lower liquid tank.

According to another embodiment of the invention, both pairs. of rollers are arranged with vertical connecting lines between the axes of associated rollers and an upwardly curved guide is arranged upstream of the forward roller pair. In this way, both copying materials pass through paths with similar transit lengths.

Preferably, the application roller has a larger diameter than a spring-loaded contact pressure roller, and the zone of contact is offset relative to the following pair of rollers in order to produce identical transit lengths.

It is important for the invention that the baths associated with the individual pairs of rollers operate with quite different liquids, and that the positive not only receives the special liquid necessary in order to enable it to perform its function, but also that this liquid is correctly distributed and incorporated thereinto.

The guides arranged in the baths are known in the art for guiding photographic film carriers or bases.

When a flock-covered or hairy-surfaces construction is mentioned, it should be mentioned that the application of the flocks is effected, by means of an electrostatic method, to a metal core, and the length of the hairs is preferably in the region of about four-tenths of a millimetre. Similarly, the abovementioned dished recesses are such that their maximum depth is of the order of a few tenths of a millimetre.

Preferably, the guide means comprise webs with rectangular cross section, arranged above the liquid and installed preferably obliquely to the direction of advance of the copying material.

In a preferred embodiment of the invention, the two bath tanks are arranged one within the other, and the bottom of the upper tank closes the lower tank, wherein an application roller with associated contact pressure roller is provided in the direction of feed at the end of the upper tank, whilethe rollers of the common pair of squeeze and transport rollers are located at the end of the lower tank, which projects beyond the upper bath tank.

In another preferred embodiment, the application roller is constructed as a hollow wetting drum, equipped with holes in its end faces through which liquid may enter into the interior of the drum. This substantially increases the available space of the special bath for the application roller.

In another preferred embodiment, weblike guide members are cast on a lower section or on a cover, and the bath tank for the receptor material, also called, for example, the nuclei container, has cast thereon corresponding guide elements defining other sides of the guide path from which segments extend to a feed opening on the inlet side.

The invention also provides a very convenient assembly in that the lower section contains supports for a nuclei bath tank, in which a wetting drum is rotatably located and affected by a spring-loaded transport and contact pressure roller, mounted in the cover of the lower section and pressing the nuclei bath tank with its support faces on to the supports. An essential feature here is that one support has a bore, and the support face is equipped with profiles forming a labyrinth seal and surrounding the bore, while mating surfaces on the support face form the other part of the labyrinth seal which is closed by the resilient contact pressure of the transport and contact pres sure roller. Hence, the resilient means for pressing on the contact pressure and transport roller simultaneously hold the assembly together, together with means, such as spring clips, provided for mounting the cover.

By using two storage tanks which are connected with the bath tank or lower section and with the nuclei bath tank, and are affected by a compression plate which is pivotable by 7 means of a spring, for compressing together the storage tanks,

sure equipment. The control speed is improved in that the spring is connected with a pin of the cam plate via an oblong hole introducing a dead motion prior to the tensioning of the spring.

Particularly preferably, the second cam plate is affected by a tension spring and a ratchet lever, and is connected with a driving wheel, having a peripheral recess or groove for a friction wheel which, after the cam plate has been released, makes driving engagement with the driving wheel for one revolution.

According to a preferred feature, the ratchet lever not only enables the cam plate to be released, but makes also possible the simultaneous switching on of the required driving motors and units and of the exposure source so long, until this engagement is taken over by a cam follower of the first cam plate. To this end, the second cam plate has preferably behind the ratchet step a cam profile extending over about 240 which holds the switch in the switched on position during a corresponding part of the revolution of the second cam plate.

The invention will be further described, by way of nonlimiting example only, with reference to the accompanying drawings, in which:

FIG. 1 is a side elevation view of a developing apparatus in cross section along the line Il-II in FIG. 2;

FIG. 2 is a partial plan view of the developing apparatus of FIG. 1 with the cover removed;

FIG. 3 is a cross section along the line IlI-IlI in FIG. 1;

FIG. 4 is a diagrammatic representation of a control device for an apparatus with the developing device of FIGS. 1 to 3;

FIG. 5 is a circuit diagram for the device according to FIG.

FIG. 6 is an end view of an apparatus with a control device according to FIG. 4, in cross section along the line VI-VI in FIG. 7; and

FIG. 7 is a view of FIG. 6 viewed from the right, with the end wall removed.

According to FIGS. 1 to 3, the developing device comprises a lower part in theform of a developing trough and having a bottom 101, end walls 102, 103 and side walls 104, 105. A connecting socket 106 leads into the bottom and can be connected to a storage tank, which will be described in greater detail in conjunction with FIG. 4.

A cover 107 is arranged above this lower part, and comprises end walls 108, 109 and side walls 110, 111.

The end wall 103 of the lower part is shorter and is formed with a copying material inlet orifice or opening 112.

In the lower part, rib-like guide elements 113, I14, etc., and 116, 117, 118, etc., are formed, such as by casting, extending substantially parallel to the side walls 104 and 105 and forming a lower limit for a sheet of copying material which is introduced through the opening 112.

As may be seen, the outlet end parts 113-115 have a raised portion 119, which terminates substantially underneath a gap between a pair of squeeze and transport rollers 120, 121. The axles of these rollers pass outwardly through the side walls 110, 111 of the cover 107 and are mounted in the frame walls 122, 123 of an apparatus in a manner which will be described in greater detail with reference to FIG. 4. A driving unit 124 is connected to one of the rollers 120, 121, and may be mounted, for example, on' the axle 125 of the roller 120.

Conveniently, the side walls 110, 111 of the cover 107 have slots extending towards their edge and shown at 126, I27, enabling the cover 107 to be lifted off.

0n opposite sides of the guide path for the sheet of copying material, formed by the guide elements 113-418, the bottom 102 is equipped with supports 128, 129 for an insert tank, the so-called nuclei bath tank 130. Corresponding supporting surfaces are provided on the bottom of this tank.

Between the supports, the bottom 131 of the nuclei bath tank is curved concavely upwards, as indicated more particularly in FIG. 1. Relative to the supporting surfaces, the bottom is so formed that it rests in spaced-relationship above the upper edges of the guide elements 113-118. The support 128 may be flat or may be curved parallel to the bottom 131. The support face 132 on the nuclei bath tank 130 has a corresponding complementary configuration.

The support 129 forms a labyrinth seal and has a centre connecting bore 133 leading therethrough, arranged in a downwardly directed socket 134 in the bottom 101 of the lower portion 100. This socket 134 communicates with a storage tank for nuclei bath liquid, as will be described further in connection with FIG. 4.

It may be seen from FIG. 3, that ribs 136 are arranged in the supporting surface 135 of the support 129, circularly surrounding the bore 133, and having, for example, a triangular cross section. Corresponding ribs 137 are provided on the supporting surface 138 on the bottom of the nuclei bath tank 130, having a downwardly directed, circular projection 139, corresponding to the diameter of the outer ribs or of the labyrinth seal.

Inside the nuclei bath tank 130 and adjacent to its side walls 140, 141 next to the upper rim of the upwardly extended base trough 131, there are arranged thrust pins 142, 143 with upwardly open bearing seats 144 (FIG. I) for shaft spindles 145, 146 of a wetting drum 147 (FIG. 1). The wetting drum, in the form of a hollow cylinder, is mounted so in the nuclei bath tank 130 that it runs with a substantial part of its periphery in the nuclei bath liquid in this tank, while projecting above its upper edge. The shaft spindles 145, 146 are mounted externally on drum end walls 148 (FIG. 1), having several perforations, of which two are shown, by way of example, at 149, 150 in FIG. 1. This has the object of utilizing the inner space of the wetting drum 147 for nuclei bath liquid, in order. to give the nuclei bath tank 130-as large a capacity as possible, while the holes produce at the same time a certain agitation effect. In this way, a substantial quantity of liquid may be kept in the nuclei bath tank 130, although the wetting drum 147 runs near the bottom trough 131 or its raised end sections.

The bottom trough 131 is equipped with further guide elements, extending on the inlet side with sections 151, 152, etc. to the feed opening 112 and at the delivery end with sections 153, 154 to near the vertical projection line of the transport and squeeze rollers 120, 121.

As shown in FIG. 2, the guide elements 151 to 154 are so arranged that they lie as far as possible in the vertical projection between the guide elements 113 to 118 of the lower part. The

' lower rims 155 of the guide elements, which define a guide path 156 for the receiving material sheet, pass in spaced relationship above the upper edges of the guide members 113- -118. The lower rims 155 extend under the bottom pan 131 between the segments at the inlet and outletsides.

The outlet side sections 153, 154 extend inside the raised edge 157 of the bottom pan 131 of the nuclei bath tank and are continued as sections 158, 159 extending into its interior, and these sections 158, 159 end at some distance from the wetting drum 147.

The cover 107 contains' corresponding guide elements 160 which are preferably laterally offset relative to the guide elements 151-154, and of which one is shown in FIG. 1'. The lower edges of these guide elements consist of two sections 161, 162, each forming, with the upper edges of the guide element sections 151, 152, and 153, 154, respectively, guide tracks 163, 164 for the sheets of receiving material. The guide track 164 extends from the opening 112 to the upper part of the drum 147, and the guide track 163 to the substantially pointed end of the sections 153, 154 of the guide elements arranged on the nuclei bath tank.

Between the rim portions 161, 162, the guide elements are recessed, forming a downwardly open cavity 165. The outermost guide elements, i.e., those near the side walls 110 and 111 of the cover, have a downwardly directed support lug 166, forming downwardly open bearing seats 167 for shaft spindles 168, 169 of a squeeze and transport roller 170. Springs 173, 174, mounted on these outer guide elements 171, 172, press the roller 170 downwardly against the drum 147. The bearings seats 167 have downwardly pointing side flanks, permitting a certain amount of bearing play and enabling the springs 173, 174 to support the shaft spindles 168, 169 in a resilient manner.

When the cover 107 has been fitted and fixed, for example, by means of spring clips 175, 176 in FIG. 3, this will not only locate the wetting drum 147 in its mounting lugs 142, 143, but also press the nuclei bath tank on the supports 128, 129, closing simultaneously the labyrinth seal with the ribs 136, 137.

The shaft spindle 169 passes through the adjacent side wall of the cover 107 and carries at its outer end 177, for example, a sprocket 178, over which is trained a chain 179 which passes over a sprocket 180 on the shaft 125. Thus, the driving unit drives the squeeze and transport rollers 120, 121 and the transport and contact pressure roller as indicated by the arrows.

It may be pointed out that the guide paths 156, on the one hand, and 163, 164 on the other hand, are so formed that they have practically the same length between the converging ends of the sections 151, 152, and 153, 154, respectively, of the guide members on the nuclei bath tank 130. In addition, a short feed table 227 for locating the copying material is formed under the feed opening 112, in the median height of which the guide element sections 151, 152 terminate.

It may be seen from the diagrammatical' representation in FIG. 4 that, for example, the transport and contact pressure roller 120 is rotatively mounted in the frame 122, 123, while the shaft spindles 181 of the transport and squeeze roller 121 are arranged in a bearing block 182 displaceable in slots 183 of the frame walls 1 22, 123 in a direction which coincides with the direction of the connecting line between the shaft spindles of the rollers 120, 121. The shaft spindles are provided at both ends of the rollers with springs 184, tending to push the shaft spindles towards each other.

In FIG. 4, the lower part 100 and the nuclei bath tank 130 are shown diagrammatically. As indicatedfurther, the connecting socket 106 communicates via a hose 185 with a storage tank 186 for the treatment fluid, namely the developer, whilst the connecting socket 134 communicates by way of a hose 187 with a storage tank 188 for the nuclei bath liquid. Both tanks 186 and 188 have a sufficient capacity for filling the, trough-shaped lower part 100 and the nuclei bath tank 130. The capacities of these containers have preferably a ratio of about 2.3 0.4. The capacity is always adapted to the liquid consumption anticipated during operation.

The storage tanks 186, 188 are arranged on a base plate 189 mounted within the frame and underneath a compression plate 190 formed with holes 191, 192 for the hose connections 185, 187. The compression plate 190 is connected by an upwardly projecting lug 190a articulately with a two-armed lever 193 which is pivotable about a pivot axis 194 located in the frame. The other end of this lever 193 is connected to a spring 195 whose other end, viz. the upper end in FIG. 4, carries an elongated eyelet 196.

An advantageous control of the apparatus will now be described with reference to FIG. 4, in which the parts are shown according to their functions.

A cam unit is mounted freely rotatably in the frame, and comprises at least one cam plate 197 and a gear 198. Conveniently, two cam plates 197 are always arranged on both frame side walls 122, 123, in order to lift the transport and squeeze roller 121 from the other roller 120 of the pair, as described further below. The arrangement at both ends has the advantage of providing at the same time a parallel guiding action for the roller 121.

Furthermore, a spindle or shaft 199 is also freely rotatably mounted in the frame. The mountings are not shown in detail. This spindle carries a driving gear 200 which meshes with the gear 198 and is so dimensioned that a transmission ratio of l 2 is formed between the shaft 199 and the cam 197. Thus, one revolution of the spindle 199 corresponds to a half-revolution of the cam plate 197.

The spindle also carries a double cam disk unit, which is firmly mounted and comprises a cam disk 201 and a drive disk arrow.

The cam disk 201 has a radially directed cam face 207, into which engages a hooked, bent end 208 of a two-armed lever 209, mounted in a pivotal bearing 210 in the frame. The other end of ratchet lever 209 carries a pushbutton 211. The ratchet lever is also affected by a spring 212, mounted in the frame, and tending to retain the hooked end 208 of the lever against the cam step 207, i.e., to guide this end along the cam disk 201.

In the frame, a switch 213-is mounted so that its actuating member 214 is located immediately in front of a pin 215 on the ratchet lever 209 so that the switch 213 is actuated when the ratchet lever is disengaged.

To the cam disk 201 is attached, for example, by means of a lug 231, and conveniently on the side on which the spindle 199 does not protrude, a spring 232 whose other end is fixed in the frame. The lug 231 is located at such a point that the spring 232 is tensioned when the cam disk 201 is retained by the ratchet lever 209, but so located, relative to the position 233, at which the spring is mounted in the frame, that the spring can move the cam disk 201, after its release, in the direction of the arrow 234, in order to engage the periphery of the drive disk 202 with the friction wheel 204.

The cam disk 197 has two peripheral sections, each extending over 180, and of which the peripheral section 216 has a smaller radius than the peripheral section 217. A rollershaped cam follower 218 is mounted movably in the frame radially'to the axis of rotation of the cam disk 197 and is connected by a linkage 219 with the actuating member of a switch 220 and with one arm 221 of a cranked lever whose other arm 22: engages be hind the shaft spindles 181 ofthe transport and squeeze roller 121. The crank lever is pivotable about a pivot 223 mounted in the frame and is affected by a spring 224,

whose other end is fixed in the frame and which tends to hold the cam follower 218 on the- cam tracks 216, 217.

The dam disk carries also a pin 225, on which the elongated eyelet 196 is located. Relative to the arrangement of the parts in the frame, the spring 195 is so long that it retains, in the relieved condition, in which the storage tanks 186, 188 are filled, the elongated eyelet 196 so that the end of the opening facing the lever 193 rests on the pin 225.

FIG. 5 shows a schematic circuit diagram. A circuit 228 is connected to a supply source 226. A further circuit 229 is completed through the two parallel switches 220 and 213 and contains, in parallel connection, the motors 206 and 124 and a light source 230.

When the copying process is to be initiated, the push button 211 is depressed, whereby the switch 213 is switched on, the

motors or drive units 206 and 124 are energized and the exposure light source 230 is connected. At the same time, the cam disk 201 is released and the spring 232 causes the drive disk 202 to engage the friction wheel 204. The switch 213 remains switched on during the first part of the spiral cam 201. The spindle 199 rotates the gear 198 with the cam disk 197 in the direction of the arrow 235. After the initial movement, the

3 steps 236, 237 are so set that the step 236 lifts the cam folclearance in the elongated hole of the eyelet 196, the spring 195, causing the compression plate 190 to move down and the developer and nuclei bath tanks 100, to be filled.

After one revolution of the cam disk 201, the ratchet or latch lever 209 drops again into the ratchet lock and stops the apparatus. The cam disk 197 has passed through only half a revolution so that the cam follower 218 is still in the raised position, shown at 218, and the cam step 237 is just in front of the cam follower 218.

The apparatus is now ready for copying. The drive motors and light sources are energized and connected by the switch 200.

When the apparatus is to be switched off after the required number of copies has been made, the pushbutton 211 is again depressed. The cam disk 201 makes a full revolution and returns the cam disk 197 into the starting position, shown in FIG. 3. The rollers 120 and 121 are disengaged from each other, the switch 220 is opened, and the compression plate is released or lifted. The profile of the cam 201 runs over about 280 behind the step 207 along an arc of a circle so that the switch 213 takes over the energizing of the motor 206 until the spring 232 can pull the step 207 against the angled end 208 of the ratchet lever 209.

Due to the elongated eyelet 196, the loading of the cam disk 197 for tensioning the spring is delayed, until the friction wheel 204 is fully in engagement with the drive disk 202. It may also be seen that the filling of tank is maintained until the spring 195 can be relieved when the cam disk 197 returns into the position shown.

In the following description of FIGS. 6 and 7, parts corresponding to those shown in the preceding description are designated by the same reference numerals.

FIG. 6 shows merely that side of the housing which contains the drive means. The developer insert may be of the construction as shown in FIG. 3. In the embodiment of FIG. 6, the frame wall 123 (in FIG. 3) is replaced by a chamber between an outer side wall 240 and an inner side wall 241, forming part of the apparatus or structure and rigidly arranged. The developer insert, with squeeze and transport rollers 121, 122 and contact pressure roller 170, is mounted in the unit, shown generally at 244. From this unit, only the shaft spindles are extended, as described below. a

The housing of FIG. 6 has a base plate 242 and a cover plate 243. Between the partition 241 and a side wall, not shown, there is the unit 244, resting on the base plate 242. The unit contains an upper bath tank, with a wetting roller according to FIGS. 1 to 3 (roller 147) and a contact pressure roller corresponding to the roller 170 in FIGS. 1 to 3. A shaft spindle of this contact pressure rolleris shown at 248 in FIG. 6 and extends into the chamber between the walls 241 and 240.

Since the contact pressure roller rests on the wetting roller, the wall 240 is provided with an oblong hole for the wetting roller. It carries, in the space between the walls 240, 241, a driving means 178, for example, a sprocket corresponding to that shown in FIG. 3, connected to a transmission 249, comprising, e.g., a chain, and driven by a further sprocket 250. This latter is mounted on a shaft 251, located on one side in the wall 240 and on the other side in a bearing wall 252. The shaft 251 extends beyond the bearing wall 252 to the partition 241 and carries a drive pinion 253, connected by a transmission 254 with an electric motor 255 which replaces the two motors 206 and 124. As indicated in FIG. 7, the transmission 254 is extended, via gear 250 or a gear mounted adjacent thereto, and via a chain 257 to a transmission gear 258, located, for example, in the outer wall 240 and connected through a transmission 250 with the squeeze and transport roller 120. I

The. shaft 251 carries, between the bearing wall 252 and the inner wall 241, a friction wheel 204 which is thus driven by the motor 255. The drive disk 202 is firmly mounted on the shaft 199 (FIG. 4): this shaft is not shown in FIG. 6, but is located in the bearing wall 252 and, for example, in the inner wall 241. It carries the cam disk 201 and the gear 200, arranged in FIG. 6 behind the gear 198.

FIG. 6 also indicates the pin 231 on the cam disk 201 and the spring 232, as well as the pivot 210 for the ratchet lever 209 in the inner wall 241. The switch 213 is mounted in the inner wall 241. The actuating knob 211, extending from the upper wall 243 of the housing, acts through a linkage on the ratchet lever 209. p

The shaft 258' for the cam disk 197 is mounted in a bearing 257 in the bearing wall 252 and in the inner wall 241 and carries the gear 198 which meshes with the gear 200. The cam disk 197 carries the pin 225 to which the spring 195 is connected via its eyelet 225. The cam follower 218 rides on the earn 197 and is connected with the switch 200 as already described above.

The lower end of the spring 195 is connected to the lever 193, whose pivot 194 is mounted on a-lug 259 on the base plate 242. The lever carries on the other end, as described above, through a pivot 1900 the pressure plate 190, underneath which the bathtanks 186 and 188 are arranged above the base of the housing, and of which the drawing shows only the conduits 185 and 187 in FIG. 6. The base plate 242, on which also the motor 255 is mounted, has holes 261 for the conduits and 262 for the spring 195.

Thus, FIGS. 6 and 7 show a mechanically possible arrangementfor the control according to FIG. 4 for mounting within the apparatus.

lclaim:

1. A developing apparatus, for the treatment of copying materials, using the silver salt diffusion method, said developing apparatus comprising, in combination, a frame; a first bath tank having a closed bottom; a second bath tank having a closed bottom; first guide means for introducing a sheet of copying material into said second bath tank for passage therethrough; an application roller rotatably mounted in said first bath tank at a position such that a major part of the periphery of said application roller is immersed in treating liquid in said first bath tank, with a minor part of the periphery of said application roller projecting above the treating liquid in said first bath tank; the enclosed bottom of said first bath tank being arcuate so that it extends in closely spaced relation to said major part of the periphery of said application roller;

said application roller comprising a hollow cylinder having tions, through the edges of the openings in its end walls, as an agitator for the treatment liquid in said first bath tank; second guide means directing a second sheet of copying material over the exposed upper peripheral portion of said application roller; said first and second guide means converging at their ends downstream of said first and second bathtanks; a pair of squeeze and transport rollers receiving the two sheets of copying material from said guide means and compressing the combined copying sheets under line contact pressure; a contact pressure roller rotatably mounted in said frame and engaging the exposed upper peripheral portion of said application roller; resilient mounting means pressing said contact pressure roller against said application roller; drive means driving at least one squeeze and transport'roller and driving said contact pressure roller; stub-shafts on the end walls of said application roller; and bearing shells on the side walls of said first bath tank rotatably mounting said stub shafts, said bearing shells opening upwardly; all parts of said developing apparatus being mounted in said frame, and said first and second bath tanks containing respective different treating liquids.

2. An apparatus as claimed in claim 1, in which the cylindrical surface of said application roller is profiled to entrain the treatment liquid in said first bath tank and, due to the pressure exerted by said contact pressure roller, effecting a concentration of the treatment liquid during dispersion and penetration thereof into the surface of said second sheet of copying material.

3. Apparatus as claimed in claim 1, in which the profiled surface of said application roller is formed by dot-like, dishshaped recesses.

4. Apparatus, as claimed in claim 1, wherein the diameter of said application roller is substantially in excess of the diameter of saidcontact pressure roller.

5. Apparatus, as claimed in claim 1, in which said first bath tank is positioned within said second bath tank; said first guide means comprising substantially vertically arranged webs projecting upwardly from the bottom of said first bath tank and weblike guide elements projecting downwardly from the bottom of said second bath tank, to define a first guide path; said second bath tank including 'a lower part and a cover; said second guide means comprising weblike guide elements extending downwardly from said cover substantially vertically and weblike guide elements extending outwardly and upwardly from the bottom of said first bath tank, and defining a second guide path; said lower part and said cover of said second bath tank defining a feed opening in one end face, and said first and second guide means having entry ends converging to said feed opening.

6. A developing apparatus for the treatment of copying materials, using the silver salt diffusion method, said apparatus comprising, in combination, a first bath tank; a second bath tank having bearings sealing said first bath tank; a cover for said second bath tank, said cover enclosing said first bath tank and being positioned on said second bath tank; one of said bearings having a bore extending therethrough and surrounded by an annular bearing surface having packing profiles; a counter-bearing on said first bath tank facing said bearing having said bore therethrough, said counter-bearing having a bore therethrough surrounded by an annular counter-bearing surface having packing profiles interfitting with the packing profiles on the annular bearing surface of said bearing; an application roller rotatably mounted in said first bath tank; a contact roller rotatably mounted in said cover in alignment with said application roller for displacement toward and away from said application roller; spring means interposed between said cover and said contact roller and pressing said contact roller into engagement with said application roller; resilient retaining means connecting said second bath tank to said cover; and bearing'means in said first bath tank rotatably supporting said application roller; whereby, in the closed state of said cover and said second bath tank, said spring means, acting through said contact roller and said application roller, establishes a closing pressure between said packing profiles to form a seal therebetween.

'7. A developing apparatus, for the treatment of copying materials, using the silver salt diffusion method, said developing apparatus comprising, in combination, a frame; a first bath tank having a closed bottom; a second bath tank having a closed bottom; first guide means introducing a sheet of copying material into said second bath tank; an application roller rotatably mounted in said first bath tank and partially submerged in treatment liquid therein; second guide means guiding a second sheet of copying material over the exposed upper surface of said application roller; said first and second guide means converging at a point downstream of said first and second bath tanks; a pair of squeeze and transport rollers compressing the combined first and second copying sheets under line contact pressure; all of said parts being mounted in said frame and said first and second bath tanks containing respective different treatment liquids; two storage tanks in said frame; first conduit means connecting one storage tank with said second bath tank; second conduit meansconnecting the other storage tank with said first bath tank; a pressure plate overlying said storage tanks; a lever pivotally mounted intermediate its ends in said frame and havingone end connected with said pressure plate; a spring connected to the other end of said lever; first and second cam disks rotatably mounted in said frame; a transmission interconnecting said first and second cam disks and having a transmission ratio of one 1:2 so that, when said second cam disk rotates through 360, said first cam disk rotates through' 180; retaining means on said first cam disk connected to said spring; and control means operable to stop said first cam disk when said retaining means are in a top dead center position and when said retaining means are in a bottom dead center position; for tensioning said spring, in the top dead center position, to depress said pressure plate to compress said storage tanks and, in the bottom dead center position, to relieve said storage tanks from the pressure exerted by said pressure plate.

8. A developing apparatus, as claimed in claim 7, wherein said retaining means comprise a pin on said first cam disk and an elongated eyelet embracing said pin; said elongated eyelet being connected with the associated end of said spring and providing for a lost motion of said first cam disk before said spring is tensioned.

9. Adeveloping apparatus, as claimed in claim 7 in which said first cam disk has a cam extending through 180; a cam follower mounted for vertical displacement in said frame and engaging said cam; a switch operable to energize driving and connecting devices included in said developing apparatus; connecting means connecting said switch to said cam follower; bearing means mounting one of said squeeze and transport rollers for displacement relative to the other squeeze and transport rollers; spring means connected to said squeeze and transport rollers and biasing said squeeze and transport rollers toward engagement; and a crank lever pivotally mounted on said frame intermediate its ends and including one arm connected to said cam follower and another arm connected to the movably mounted squeeze and transport rollers; said crank lever raising said movably mounted squeeze and transport roller off the other squeeze and transport roller when said switch is open.

10. A developing apparatus, as claimed in claim 7, in which said second cam disk has a cam on its periphery including a shoulder interconnecting adjacent ends of said cam; a spring loaded actuating lever pivotally mounted, intermediate its ends, in said frame and having a lug engaging said cam and engageable with said shoulder; spring means having one end secured to support means fixed on said frame and an opposite end secured at a point on said second cam disk such that said spring means is tensioned when said lug engages said shoulder and can contract whcnsaid lug disengages said shoulder; a further drive disk fixedly connected with said second cam disk, and having a peripheral recess; a friction wheel mounted in said frame at a position wherein it can contact said drive disk, when said peripheral recess is moved toward said friction wheel, and disengages said drive disk when said recess is aligned with said friction wheel; drive means mounted in said frame; and a transmission interconnecting said drive means and said friction wheel.

11. A developing apparatus, as claimed in claim 10, in which said spring loaded actuating lever has a second lug; a second switch mounted in said frame and including a switch actuating lever in the path of movement of said second switch; said second lug operating said switch actuating lever to close said second switch when the first mentioned lug is disengaged from said shoulder; a light source on said frame; said second switch controlling energization of said apparatus and said drive means and controlling energization of said light source; said second cam disk having a circular cam profile extending through substantially 280 behind said cam shoulder.

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