US2605684A - Apparatus for semiwet development of photoprints - Google Patents

Description

Au'g. 5, F. NAGELs ErAL 2,505,534

APPARATUS FOR SEMIWET DEVELOPMENT OF PHOTOPRlNTS md oct. 5. 1948 SHEETS-Smm 1 MM Qgwil H TTRNEKF Allg- 5, 1952 F. NAGELS ET AL 2,605,684

APPARATUS FOR SEMIWET DEVELOPMENT OF PHOTOPRINTS Filed oct. 5. 1948 2 Simms-SHEET 2 'I l l l l l l l l l O O` O o Q' o O O O O O O O O O JMPA/N55 Afl/afwas 5an/.vou5 55u-w l All/EN 71795 Patented Aug. 5, 1952 UNITED STATES PATENT OFFICE APPARATUS FOBl SEMIWET DEVELOPMENT OF PHOTOPRINTSl Application October 5, 1948, Serial No. 52,924 In the Netherlands October 6, 1947 14 Claims.

The invention relates to apparatus for semi- Wet development of photoprints, adapted to apply a thin film of the developing liquid to the material to be developed, said apparatus being provided with a rotary liquid-applying-roller, having in its circumferential surface a plurality of channels or grooves extending transversely to the axis of the roller and further of the type in which a rotary liquid-transmitting-roller is interposed in the path of the liquid supply to the grooved applying roller.

Apparatus of the kind referred to is well known from U. S. Patent 2,241,104 (to compare page 4, right column, lines 39-55) where the transmitting-roller has been called an auxiliary roller. If certain requirements described in this patent, are satised, apparatus of the kind referred to applies an even liquid layer of definite thickness (e. g. 8 cubic centimeters, viz. 8 grammes when the specic gravity of the liquid is l, per sq. metre) to the material to be developed. The thickness oi the layer (expressed in the number of grammes per sq. metre) which the apparatus supplies to the photoprint material, however, is dependent on the speed with which it is operating (compare e. g. U. S. Patent 2,241,104, page 4, left column, lines 66-69). For a required thickness of the liquid layer, i. e. for a required application, determined by the requirements of the necessary development, the apparatus has to be operated at a fixed speed i. e. its speed has to be controlled.

Consequently it is not possible to choose the speed arbitrarily, e. g. in adaptation to the speed with which the photoprinting paper is running through a preceding exposure apparatus, or in adaption to other working requirements.

The object of the invention is to make the application of liquid less dependent on the operating speed, meanwhile however maintaining an application roller having grooves or cross channels for the sake of its inherent advantages. These advantages are that such channeled rollers only cause a small stained edge at the end edge of the sheets to be developed and only little starter (under development) at their starting edge. (For this starter compare U. S. Patent 2,241,104, page 2, left column, line 33).

For that purpose, according to the invention, in a developing machine of the kind referred to the capillary liquid applying roller is operated in contact with a liquid transmitting or auxiliary roller which replenishes the channels of the applying roller, and the transmitting roller is caused to cooperate with a raking or doctor- 2 device which limits the quantity of liquidtransmitted via its surface.

Normally a cross grooved applying roller has an excess of liquid available for application, sothat every demand for liquid that is made by the material to be developed can be satisned (which demand increases with the speed)- In the apparatus according to the invention, the provision with liquid of this grooved application roller itself is limited, with the result that the issue capacity of the roller can no longer satisfy the demand unrestrictedly.

Even in case of largely varying speeds apparatus according to the invention gives only a slight difference in application of the developer. By designing the limiting raking or doctor-device adequately it is possible to fix rather exactly the number of grammes of developer per sq. metre applied by the cross grooved applying roller to the material to be copied. When the apparatus is thus set for the application of an average quantity of 8 grammes developer per sq. metre the grooved roller will at a speed of eJg. 25-30 centimetres per minute apply 7.5 grammes per sq. metre to material to be developed and passed over the roller, while this application is 8.5 grammes per sq. metre at a speed of e. g. 6 7 metres per minute.

Developments with '7.5 and 8.5 grammes per sq. metre do not differ inconveniently from one another for the practice of the diazotype process. By this invention good developments in practice are obtained even at speed variations of 1 to almost 30. This means an important improvement in the iield of diazotype-developrnent.

As has been stipulated in the U. S. Patent 2,241,104 the rotating cross grooved applying roller which applies the developer to the material to be developed must have a relatively large passage (compare U. S. Patent 2,241,104, page 4, left column, line 12) e. g. 20-30 mm.2 (sq. millimetre) per decimeter length in order to meet with practical requirements.

Tests have been made with doctoring oi the cross grooves themselves instead of doctoring off the transmittingor auxiliary-roller, but without any favourable result.' v

It has appeared in the practice of the diazotype-development that difficulties may occur, when the developing machine according to the invention is not in all its parts equipped for socalled "parallel run i. e. that the surface o1' the material under treatment and that of the roller cooperating with it are moving in the same direction. Preferably the material to be developed Will be made to run with a speed equal or almost equal to that of the grooved roller. Also stationary doctoring parts, which may cause troubles, preferably will be avoided. Diioulties e. g. may occur owing to the formation of crystal crusts from the developer, to iilthiness of the developer and of the material to be developed, to particles detached from the crusts etc. Consequently the doctor-device is preferably of the kind comprising at least one rotating roller.

In the drawings:

The Figures 1-5 are diagrammatic sectional elevations of various embodiments of the liquidapplication-section of developing'apparatus.

Fig. 6 is a partial longitudinal section of a cross grooved roller.

Fig. '7 shows part of a doctor-blade or doctor'- knife.

Fig. 8 is a partial elevation of a roller adapted to be used as an auxiliaryor doctoring-roller.

v Fig. 9 represents part of the surface of another embodiment of such an auxiliaryor doctoring-roller.

In the Figures 1-5, I represents a roller of a diameter of millimetres consisting of a metal core 2 coated with 21/2 mm. of a suitable synthetic material 3, which contains helically wound cross grooves 6 (see Fig. 6). The helix has a pitch of 0.5 mm., the grooves have a Width of 0.15 mm. and a depth of 0.8 mm. So this cross grooved roller has a passage" of 2v00 0.8 0.15 :24 mm2 per decimeter of axial roller length.

In Fig. 5 there are two applying-rollers I and -I with cross grooves. This equipment is used for two-sided development. S represents in Figs. 1-5 the material to be developed, which passes in the direction of the arrow over the grooved roller(s).

In Figs. 1-4 this material is kept in contact with the cross grooved roller by the guiding rollers 4 and 5.

They revolve in the direction of the arrows. In the developing apparatus according to Fig. 5 these guiding rollers are superfluous. It will be understood that all the developing apparatuses illustrated also have other guiding and supporting devices as usually used in such machines. For the sake of simplicity they are not represented in the figures.

In Fig. 5, 'I and 'I' are auxiliary-transmission rollers cooperating with the cross grooved roller I and I' respectively. 'I'he guttershaped reservoirs 9 and 9 contain the developer liquid I0 and I0'. The auxiliary "I in Figs. 1 to 4 function in essentially the same way, except that .in Fig. 3 roller 'I does not dip into the reservoir.

The various rollers rotate in the directions indicated by the arrows.

In Fig. 1 the transmission roller 'I by its rotation carries the liquid I0 upwards. The doctor blade I3, illustrated in Fig. 'I has recesses I4 at distances of 4 mm. that are 0.1 mm. deep and 0.3 mm. wide. Roller 'I has a smooth surface. Thus in the cooperation of transmission roller 'I with doctor blade I3 there is a passage of 0.75 mm. 2 per decimetre of axial roller length. The quantity of liquid that passes through and is limited by this passage and which is carried to the cross grooved roller I is such that roller I at speeds of cm. to 6 metres per min. applies about 8 grammes viz. 8 cubic centimetres per sq. metre to the material S that is to be developed.

In this arrangement the quantity of liquid taken by the material S from roller I is also dependent on the surface structure of that material to a slight degree only. Instead of having a smooth surface, roller 'I can also be provided with helically wound canals I5 on its surface, as represented by Fig. 8. When the helix of these canals has a pitch of 4. mm. and the canals I5 have a cross section of 0.1 x 0.3 nini. and when the doctor blade I3 is without recesses, consequently with a straight sliding edge, the result obtained will be quite analogous to that of a smooth roller 'I' combined with a doctor blade according to Fis. 7.

Fig. 2 illustrates an arrangement that is identical in principle to that of Fig. 1.

The doctor blade I3 has been substituted by a doctoring-roller I6. chosen for this doctoring roller it will be possible to equip roller 'I with canals as described and as represented by Fig. 8. If on the contrary roller 'i has a smooth surface, roller IS is to be equipped with appropriate canals. t is also possible to equip the rollers 'I or IG with pits lI as represented in Fig. 9, which pits have been evenly distributed over the surface of the roller, in such a manner that the contents (the total volume) of the pits is approximately the same as the contents (the total volume) of the canals described for roller I.

It is also possible to provide roller I and roller I5 both with canals or pits; the limitation of the liquid then is determined by the sum of both the passages As a matter of fact this system of liquid limitation can also be applied to the apparatus according to Fig. 1 and also to those according to the Figures 3 to 5. As described before, the limiting passages cause the cross grooved roller I to produce an application of about 8 grammes per sq. metre at various speeds. If desired this passage and consequently the liquid application can be decreased or (which, however, as a rule is undesirable) increased. In Fig. 3 the doctoring roller I 6 also acts as a supplying roller for the transmission or auxiliary roller 'I. It is mounted on the right-hand side of roller 'I, i. e. on the side on which the surface of roller I moves upwards and drags liquid from the gutter 9. A stcwing meniscus is formed under the line of contact of the rollers 'I and IE. If roller I6 should be on the left hand side of roller 1, the meniscus would be formed above the mentioned line of contact. That embodiment is also possible. In Fig. 4 the rollers I and I5 both act as supplying rollers. The upper part of the roller I, above the line of Contact with roller IG provides for the transmission of liquid to the appli-- cation roller I.

As stated already the rollers l and I in r'g. 5 are the cross grooved rollers that apply liquid to both sides of the material S to be developed. Cross grooved roller I cooperates with transmission roller` I; cross grooved roller I with transmission roller 'I'. In principle in the manner of Fig. 2 the roller 22 doctors off roller 1 and roller 22 doctors off roller 'I'. The applying rollers I and I can also be supplied with liquid via a series of rollers instead of one roller (a series of rollers arranged one behind the other and contacting each other in succession).

It is sufcient if one of them has a limited transmission, i. e. if it is doctored to a certain extent as described above for the roller 'I and 'I'.

As mentioned before developing apparatus according to the invention are particularly adapted for use in combination with an exposure apparatus for continuous exposure of photoprinting material e. g. diazotype paper. In practice printing is preferably done on a long uninterrupted If a smooth surface is' band of light-sensitive paper, which passes through the exposure apparatus e. g. over a glass cylinder surrounding a tubular lamp, the tracings to be copied being carried along between the glass cylinder and the band of light-sensitive paper. The transparency of the tracings varies in practice and in order to obtain the right exposures the exposing cylinder is made tok run quickly in case of a more transparent tracing and slowly in case of a less transparent one. So the band cf material to be developed that leaves the exposure apparatus will have a speed that is variable Within rather wide limits.

In combined exposureand developing machines this band will nevertheless be required to pass as a Whole continuously through the developing machine immediately after the tracings have been exposed and removed.

The developing machine according to the invention is extremely suitable for that purpose, and its driving mechanism is advantageously adapted to move with more than one speed, while in the combination with a continuously operating exposure apparatus the driving devices advantageously can be chosen in such manner that the developingand the exposure-sections are operated at speeds adapted to one another, the speed of the combination being variable. The speed variation can amount from a certain minimum speed to a fold speed.

In order to promote the straight running of the paper band all through the exposure and developing combination the developing section according to the invention is advantageously given a speed. of some per-cents greater than that of the exposure section. Owing to this procedure some slip arises in the contact zone between the material S to be developed and the developing roller I and it is notoriously an advantage of the developing machine according to the invention that no drawback is experienced from such difference in speed.

The various rollers in the machine according to the invention can be made of any suitable material.

They may be hard or weak. As to the doctoring zone care will have to be taken, however, that the passage keeps its required measurements notwithstanding the deformation taking place in weak material under the prevailing pressure.

The only general requirement for the material to be used is that it has to be non corrosive. So preferably iron or brass is avoided but e. g. stainless steel, rubber, synthetic materials glass etc. are recommended.

What we claim is:

l. The method of reducing the speed-dependency of the rate of application of a liquid photoprint developer to a moving photoprint material from a roller surface formed with evenly distributed capillary-active grooves extending transverse to its axis and holding an amount of such developer liquid per unit of surface area many times exceeding that ever to be applied for developing a like unit of area of the material, which comprises, while rotating said surface in contact with the moving material to apply the developer liquid thereto from said'grooves, supplying developer for replenishing said grooves evenly across a part of said surface away from the material in a volume per unit of roller surface area not exceeding the volume required for developing a like unit of area of the material.

2. The method of reducing the speed-dependency of the rate of application of a liquid photoprint developer to a moving photoprint material from a capillary roller surface formed with evenly distributed capillary-active grooves extending transverse to its axis and holding an amount of such developer liquid per unit of surface area many times exceeding that ever to be applied for developing a like unit of area of the material, which comprises, while turning said capillary surface in contact with the moving material, supplying developer liquid for replenishing said grooves to a transfer roller surface turning in contact with said capillary surface, and doctoring the developer on the transfer surface ahead of the capillary surface to a predetermined volume per unit of transfer surface area not exceeding the volume required for developing a like unit of area of said material.

3. The method of reducing the speed-dependency of the rate of application of a liquid photoprint developer to a moving photoprint material from a capillary roller surface formed with evenly distributed capillary-active grooves extending transverse to its axis and holding an amount of such developer liquid per unit of surface area many times exceeding that ever to be applied for developing a like unit of area of the material, which comprises, while turning said capillary surface in contact with the moving material, supplying developer liquid for replenishing said grooves to a transfer roller surface turning in contact with said capillary surface, and limiting the supply on the transfer surface ahead of the capillary surface to an amount per unit of surface area approximating that which the capillary surface applies to a like unit of area of the moving material at its minimum working speed.

4. The method of reducing the speed-dependency of the rate of application of a liquid photoprint developer to a moving photoprint material from a capillary roller surface formed With evenly distributed capillary-active grooves extending transverse to its axis and holding an amount of such developer liquid per unit of surface area many times.v exceeding that ever to be applied for developing a like unit of area of the material, which comprises, while turning part of said capillary surface in contact with and in the direction of the moving material, supplying developer liquid for replenishingsaid grooves to a transfer roller surface turning in contact with and in the direction of an opposite part of said capillary surface, and doctoring the developer on the transfer surface ahead of the capillary surface to a predetermined volume per unit of transfer surface area not exceeding the volume required for developing a like unit of area of said material.

5. In an apparatus for the semi-wet development of moving photoprint material, a rotatable liquid applying roller having a circumferential surface to contact said material formed with evenly distributed capillary-active grooves that extend transverse to its axis and hold an amount of developer liquid per unit of roller surface area many times exceeding the amount ever required for developing a like unit of area of the material, a liquid transfer roller having its surface rotated in contact with said capillary surface, means for supplying developer liquid to said transfer surface, and a doctoring device contacting said transfer surface and forming with it ahead of said capillary surface a limited liquid supply passage of predetermined cross sectional area distributed evenly over its axial dimension.

6..Invan apparatus for the semi-wet development of moving photoprint material, a liquid applying roller having a circumferential surface to contact said material formed with evenly distributed capillary-active grooves that extend transverse to its axis and holdan amount of developer liquid per unit of roller surface area many times exceeding the amount ever required for developing alike unit of area of the material,

vmeans for rotating said roller, aliquid transfer Vroller having its surface rotated in contact with said capillary surface, meansfor supplying .dev eloper to said transfer surface, and a doctoring device `contacting said transfersurface and forming with it Aahead of said capillary surface a .limited liquid supply passage of `predetermined cross sectional area distributed evenly .over its axial dimension, said cross sectional areaper unit of .axial dimension being approximately the same as the effective cross sectional area of the amount of said developer which `the capillary surface applies to a like unit dimension of the moving material at its minimum working speed.

7. An apparatus asdescribed .in claim 5, said doctoring device comprising a-roller krotating in Contact with and in the direction of movement of the transfer roller surface.

A8. An apparatus as described in claim 7, said transfer roller surface being formed uniformly with a multiplicity of evenly spaced recesses to provide the limited supply passage.

9. An apparatus as described in claim '7, the contacting surface of said doctoring roller being formed uniformly with a multiplicity of evenly spaced recesses to provide the limited supplyr passage.

10. An apparatus as described in claim 5, said doctoring device comprising a substantially sta-- tionary blade contacting said transfer surface at a multiplicity of points spaced evenly along its axis and having evenly spaced recesses `between said points forming said limited supply passage.

1l. An apparatus as described .in claim r5 comprising variable speed means for rotating saidV rollers to accommodate their surface speed to varying speeds of movement of said material.

12. An apparatus as described in claim 5, said doctoring device comprising a roller rotating in contact with and in the direction of the transfer roller surface, said liquid supplying means including a container for a body of said liquid into which the lowermost part of said doctoring roller extends below the normal level of the liquid body v8 so that the doctoring roller bath carries liquid to and limits the supply transferred on the transfer roller surface.

13. An apparatus as described in claim 12, the lowermost part of said transfer roller surface being disposed below said normal level.

14. Apparatus for the consecutive exposure and semi-Wet development of moving photoprint material, comprising an exposure cylinder rotatable at variable speeds to expose a band of such material passing about the cylinder, a developer liquid applying roller arranged to engage said band beyond the cylinder, said roller having its circumferential surface formed with evenly distributed ,capillary-active grooves that extend transverse to its axisand hold an amount of developer liquid per unit yof roller surface area many times exceeding the amount ever required for developing a like unit of area of Asaid material, means for drawing said band about said cylinder and over said roller at variable speed, Variable speed means for rotating said roller surface in the direction of movement of said band, a, liquid transfer roller having its surface rotated in contact with said capillary surface, means for supplying developer liquid to said .transfer surface, and a doctoring device contacting said transfer surface and forming with it ahead of said capillary surface a limited liquid supply passage of predetermined cross sectional area distributed evenly over its axial dimension. FREDERIK NAGELS.

JOHANNES HUBERTUS GERARDUS SELEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 687,481 Kammerer et al. Nov. 26, 1901 801,552 Sherwood Oct. 10, 1905 911,241 Inman Feb. 2, 1909 2,241,104 Grinten May 6, 1941 2,249,089 Murray et al. July 15,1941

2,265,856 Reed et al. Dec. 9, 1941 '2,524,818 McHugh Oct. 10, 1951 FOREIGN PATENTS Number Country Date 298,965 Great Britain Oct. 18, v1928 519,243 Germany Feb. 25, 1931 591,075 Germany Jan. 15,1934

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