Apparatus for the liquid-processing of light-sensitive sheet material

An apparatus for liquid-processing light-sensitive sheets comprises a processing dish preferably with a horizontal intermediate bottom. The upper side of the intermediate bottom constitutes the lower, and the underside of a lid covering the dish the upper, wall of a passage-gap through which the sheets are transported by pairs of conveying-and-squeezing rollers. The downstream dish sidewall, taken in sheet-transportation direction, is provided near its foot with a horizontal row of injection-nozzles for processing liquid. The dish sidewall opposite the nozzle-bearing sidewall bears a horizontally extending ledge or appropriate flow-reversing configuration effecting 180.degree. reversal of the direction of liquid flow from underneath the intermediate bottom to above the profiled bottom-surface and toward the nozzle-bearing sidewall, generating a liquid stream through the passage-gap in the sheet-transportation direction. The bottom surface possesses a profiling comprising gable roof tile-like faces extending transverse to the sheet-transportation direction.

BACKGROUND OF THE INVENTION 
This invention relates to apparatus for the liquid-processing of 
light-sensitive sheet material being transported through the apparatus 
which comprises 
at least one processing dish, having sidewalls, 
lid means having an underside and covering such dish, 
at least one bottom-surface extending substantially parallel with and at a 
distance underneath said lid means, thus forming 
at least one passage-gap extending between the lid means underside and the 
bottom surface and being adapted for being passed by processing liquid in 
the same direction in which the sheet material is being transported 
through the apparatus, and 
means for transporting sheets of said sheet material successively through 
said passage gap. 
The upper surface of the bottom wall of the processing dish may constitute 
the bottom-surface delimiting the said passage-gap below. 
In preferred embodiments of such apparatus that bottom-surface is 
constituted by the upper side of an intermediate bottom element about 
which the processing liquid can be circulated. Such preferred embodiment 
of the apparatus is described, for instance, in the European Patent 
application No. 83-810,346.3, having the Publication No. 105,833. In this 
apparatus, the intermediate bottom element in the processing dish bears on 
its upper side, constituting the lower wall defining the sheet 
passage-gap, a pattern of slender upright pins. Thereby, conditions for 
the passage of liquid are to be provided throughout the gap which are as 
uniform as possible, thereby presenting the lowest possible flow 
resistance and avoiding the formation of preferential directions of flow 
of partial liquid streams. 
OBJECTS AND SUMMARY OF THE INVENTION 
It is an object of the invention to provide an apparatus of the 
above-described kind comprising an improved profiling of the 
bottom-surface forming the lower wall of the passage-gap, thereby 
substantially improving the homogeneity of the liquid flow through the 
passage-gap. 
This object is obtained by providing an apparatus of the above-described 
kind in which the bottom-surface has an asymmetrical, gable roof-like 
profiling having the aspect of overlapping rows of roof tiles extending 
transverse to the direction of sheet-transportation either on the top face 
of the dish bottom wall or base-plate of the apparatus or, preferably, on 
the top face of an intermediate bottom element in the aforesaid processing 
dish. 
Preferred embodiments of the apparatus according to the invention show one 
or several of the following advantageous features: 
(a) The transversely extending profile tile faces facing upstream toward, 
i.e. opposing, the direction of sheet-transportation and liquid flow and a 
horizontal plane, or the general plane in which the sheet material is 
transported, enclose between them a smaller angle (.alpha.), preferably of 
at most 60.degree., more preferedly of 5.degree. to 30.degree., than the 
profile (tile) faces facing downstream, i.e. in the same direction in 
which the sheet material is transported and in which the liquid flows over 
the bottom-surface. 
(b) The downstream-facing profile (tile) faces and the horizontal 
plane,--which can, for instance, be defined by the general plane in which 
the sheet material passes through the passage-gap,--enclose preferably an 
angle (.beta.) of about 30.degree. to 120.degree., and optimally of 
45.degree. to 90.degree.. 
(c) The crest formed by adjacent downstream and upstream profile (tile) 
faces of the profiling has preferably a height of about 1 to 10 mm, 
optionally about 2 to 5 mm above the deepest level of the next-adjacent 
groove. 
(d) The internal width (D) of the passage-gap perpendicular to the said 
general plane in which the sheets pass therethrough is preferably 1 to 10 
mm, and optionally 3 to 5 mm. 
(e) The crest region between an upstream-facing and an adjacent 
downstream-facing profile face following downstream, i.e. in the direction 
of sheet-transportation, can be flattened to form a flat, horizontally 
extending intermediate top face. 
(f) The length of such flat, horizontally extending top face, taken in the 
direction of sheet-transportation is preferably about one quarter to one 
half of the length of the upstream-facing profile face, and most 
preferredly about one third of that profile face, the surface of that 
horizontal top face being preferably polished, e.g. by fine grinding, 
lapping or the like. 
(g) Small guiding elements can be provided at and protrude from the 
downstream edge or crest of a last profile (tile) face, for instance of 
the upstream one, taken in the direction of sheet-transportation; these 
guiding elements preferably extend beyond the downstream end of the 
intermediate bottom wall to the vicinity of a downstream end wall of the 
processing dish, passages for the flow of processing liquid being left 
free between these guiding elements.

DETAILED DESCRIPTION OF THE EMBODIMENTS SHOWN IN THE DRAWINGS 
In the figures of the Drawings, reference numeral 1 designates a processing 
dish and 2 an intermediate bottom. The intermediate bottom bears on its 
underside supporting end plates, feet or the like means 4 standing in the 
processing dish 1, as well as spacer members 5 in its central region, 
which rest on the dish bottom 10. The spacer members 5 are either firmly 
connected with the intermediate bottom 2 or they form an integral part of 
the same. Preferably, at least one of the spacer members 5 is anchored on 
the dish bottom 10 by means of a snap or screw connection 6. Thereby, the 
intermediate bottom 2 is safely secured on the dish bottom 10 against 
being lifted off by a strong liquid current passing underneath the 
intermediate bottom 2. 
The transportation of the sheets to be treated is effected by conveying and 
squeezing roller pairs 71/72 and 73/74. Preferably, the upper roller, 71 
and 73, of each pair is drivable directly by a motor, and the lower roller 
is freewheeling or is connected with the drive by means of an elastic 
transmission member. 
Between the dish sidewalls 11 and 12, which extend transverse to the 
direction of sheet-transportation T, and the end or rim walls 21 and 22 of 
the intermediate bottom 2, there are left free terminal gaps 31 and 32, 
respectively. The sidewall 12 located downstream with regard to the 
direction of sheet-transportation T, is designed with a hollow profile, as 
a liquid distributor 121, and bears below the level of the intermediate 
bottom 2 a row of, for instance, 20 to 25 injection nozzles 120 for the 
processing liquid, which nozzles are distributed in horizontal arrangement 
over a distance of 250 mm. The sidewall 11 upstream with regard to the 
direction of sheet-transportation T is devised as an overflow for the 
liquid into a collecting channel 8. A collecting channel 9 is also 
arranged next to the downstream dish sidewall 12, which channel collects 
the liquid squeezed out from the passing sheets by the roller pair 73/74 
and any liquid passing over the sidewall 12. 
Only the first processing station has been completely shown in the 
drawings. A complete apparatus ordinarily comprises several, in particular 
three or four stations arranged in series, for instance, in the case of 
the silver bleach process, firstly a developing station, and 
next-following one or two bleaching stations and finally a fixing station. 
All stations are built in an identical manner. Only an upstream portion of 
the processing dish lB including the upstream dish sidewall llB and the 
associated collecting channel 8B of the second processing station B is 
therefore shown in FIG. 1. 
As indicated in FIG. 1, all stations are mounted on a common base-plate 
1000 which comprises in a continuous manner the bottom walls 10, lOB etc. 
of the processing dishes 1, lB etc., as well as all bottom walls 80, 90, 
80B etc. of the collecting channels 8, 9, 8B, respectively. Apart from the 
first roller pair 71/72, each of the following roller pairs 73/74 with the 
exception of the last pair 73/74 (not shown) is common to two successive 
processing stations. 
Underneath the processing dish 1 and the collecting channels 8 and 9, there 
is arranged at the base-plate 1000 a storage-and-buffer vessel 7 which is 
open at the top and the upper rim of which is firmly connected with the 
underside of the base-plate by gluing or welding. The volume ratio between 
the storage and buffer vessel 7 and the processing dish 1 amounts to about 
1.5 to 2.5, and is preferably about 1.8. 
The collecting channels 8 and 9 are provided with bottom discharge outlets 
81 and 91, respectively through which liquid can flow into the vessel 7. 
The reference numeral 70 designates a vent hole for the vessel 7, and 100 
designates discharge openings for the processing dish 1. 
The sidewalls of the storage-and-buffer vessel 7 are devised to converge 
downwardly in the shape of a funnel. From the lowermost point of the 
vessel 7 a conduit 60 leads to the suction side of a circulating pump 601 
whose pressure side is connected with a liquid distributor 121 via a 
thermostatically controlled heater 602 and a conduit 63. Moreover, a check 
valve-controlled bottom discharge outlet 700 is provided at that lowermost 
point. 
The stations succeeding the first, above-described one in the direction of 
sheet-transportation T are provided in turn each with the same arrangement 
of a storage-and-buffer vessel and a circulating pump etc. In FIG. 1 there 
is only shown a wall of the vessel and its vent hole, and one of the 
discharge openings of the processing dish, and these parts have been 
designated correspondingly with 7B, 70B and lOOB, respectively. 
Preferably, in analogy with the common base plate 1000, the storage and 
buffer vessels 7, 7B etc. of all stations are constituted by a single, 
integral building element whose upper rim faces are glued or welded to the 
base plate 1000. 
Liquid is pressure-pumped by means of the circulating pump 601 via the 
thermostatically controlled heater 602 and via the distributor 121 to 
liquid-feeding nozzles 120 and through these into the processing dish 1. 
Excess liquid flowing over and down the outside of the dish sidewalls 11 
and 12 is led via the collecting channels 8 and 9 to the 
storage-and-buffer vessel 7 and is returned from there to the pump 601. 
The discharge openings 100 are dimensioned sufficiently narrow to permit 
only a small fraction of the quantity of liquid fed through the nozzles 
120 to run off during operation. 
The entire circulating system, and in particular its pump 601 and the 
cross-sectional areas of the liquid-feeding nozzles 120 are so dimensioned 
that the liquid enters the processing dish at a flow rate of at least 0.5 
m/sec and preferably at about 1 to 3 m/sec. The liquid-feeding nozzles 120 
preferably have a diameter of about 1 to 2 mm, and optimally of 1.5 mm, 
and are arranged at a mutual distance of 10 to 30 mm, and optimally about 
20 mm, in the lower quarter of the dish sidewall. Preferably, the pump 
output and thereby the feeding flow rate are adjustably controlled. 
The upstream-located sidewall 11 of the processing dish 1 is shaped in a 
manner such that the liquid which flows against it in the lower sidewall 
part is deflected upwardly and its direction of flow is reversed. For this 
purpose, the wall 11 as a whole can be correspondingly shaped, i.e. 
convexly on its liquid-contacted, and concavely on its outer side. In FIG. 
1, however, this wall is shown to be planar and provided, above the level 
of the intermediate bottom 2, with a horizontally protruding 
direction-changing ledge 110. This ledge can be glued or welded to the 
sidewall 11 or molded integral therewith. The ledge 110 projects into the 
dish 1 sufficiently to have its longitudinal edge located vertically 
spaced above and shortly before or behind the upstream rim of the 
intermediate bottom element. 
Due to the liquid being fed through the liquid-feeding nozzles 120 into the 
dish 1 at a relatively high velocity, there is generated below the 
intermediate bottom 2 a string liquid current SU in a direction opposite 
the direction of sheet-transportation T. This current is deflected at the 
oppositely located dish sidewall 11 upwardly and with a major portion 
thereof to stream above the intermediate bottom in the direction of 
sheet-transportation T and back toward the sidewall 12. This return-flow 
portion is symbolized by an arrow SO. The liquid flowing back above the 
intermediate bottom 2 and in the direction of sheet-transportation T is 
drawn downwardly at the sidewall 12, due to the strong ejector effect of 
the liquid being ejected from the liquid-feeding nozzles 120 into the 
dish, and is accelerated again back toward the opposite dish sidewall. The 
reversal of the flow direction from below upwardly is symbolized by the 
arrow SU/SO and the reversal from above downwardly correspondingly by the 
arrow SO/SU. A portion of the liquid which is symbolized by an arrow SUE, 
flows in particular over the top and down the outside of the dish sidewall 
12. The major portion of the liquid circulates about the intermediate 
bottom 2 (counterclockwise in FIG. 1), the liquid flow being generated and 
continuously maintained by the overflowing liquid stream which is 
recirculated by the pump 601, and by the ejector effect caused by the 
liquid being pressed through the nozzles 120. 
The upper surface of the intermediate bottom 2 is constituted by an 
asymmetrically gable roof-like profile extending transversely to the 
direction of sheet-transportation T. The faces FF of this profile, facing 
in a direction opposed to the transportation direction T are of relatively 
small inclination and enclose, together with a horizontal plane indicated 
by a dashed line, an angle .alpha. of at most 60.degree.; preferably, 
however, of only 5.degree. to 30.degree.. The adjoining faces FS, however, 
are inclined more steeply, as shown in the drawings, and enclose with the 
horizontal plane an angle .beta. of 30.degree. to 120.degree., and 
preferably of 45.degree. to 90.degree.. The height h of the crest of the 
profiling amounts in practice to about 1 to 10 mm, and preferably to 2 to 
5 mm. This arrangement of the profiled bottom-surface together with the 
underside of the dish lid 3 forms the passage-gap D. Due to the effect of 
the described profiling of the bottom-surface, there is achieved a 
homogeneous through-flow of the liquid through the passage-gap D, and at 
the same time a satisfactory passage of the sheets therethrough is 
guaranteed. The width of the gap D amounts to about 3 to 10 mm, and 
preferably to about 7 mm, and can be devised to be changeable or 
selectively adjustable. 
In the embodiment of the intermediate bottom element illustrated in FIGS. 3 
to 5, a horizontally extending face FH having preferably a polished 
surface, is interposed between the gently sloped upstream-facing profile 
face FF and the steeply inclined downstream-facing profile face FS. Taken 
in the direction of sheet-transportation, the length of this interposed 
face FH amounts to one quarter to one half, and preferably to one third of 
the length of the gently sloped face FF. 
At the last profile face crest, taken in the direction of sheet 
transportation, there are provided guiding elements FU which extend beyond 
the downstream end 21 of the intermediate bottom 2 toward and close to the 
downstream dish sidewall 12. These guiding elements FU appear to be quite 
narrow, especially when regarded from above (FIG. 5), so that they do not 
impair the liquid flow SO/SU. They have approximately the same angle of 
ascent as the upstream-facing profile faces FF and improve the guidance of 
the sheets in the exiting region of the dish 1. 
The entry and exit regions of the passage-gap D are designated hereinafter 
as sheet-entry gap and sheet-exit gap and are formed, respectively, by the 
upper edges of the sidewalls 11 and 12, and oppositely located guiding 
faces of the lid 3. In this case, the rim of dish sidewall 11 located at 
the sheet entry side is inwardly and upwardly tapered at an angle of about 
20.degree. C. to 40.degree., and preferably of about 30.degree.. The lid 3 
is provided at the sheet-entry gap with a guiding face 311 being inclined 
downwardly in the direction of sheet-transportation, and is located 
exactly opposite the tapered dish rim face 111, enclosing with the latter 
an angle of about 30.degree. to 60.degree. and having a visible transition 
zone 312 in the shape of a flat edge via-a-vis the adjacent flatter, less 
inclined guiding face of the lid. Thereby, there is achieved a wetting 
line, vertical with regard to the sheet-transporting direction T, which is 
as straight as possible. 
The dish rim on the side of the sheet exit is tapered analogous, in the 
sheet-exiting direction T, ascending at an angle of about 20.degree. to 
60.degree., and preferably about 45.degree., and with rounded edges to 
form an upwardly sheet-guiding face 122. The lid 3 is further provided in 
the sheet-exiting region with an outwardly and gently upwardly tapered 
guiding face 322 which ends in a recessed step 323 in the lid underside. 
This step 323 is located between the exit-side (downstream) end of the 
intermediate bottom 2 and the guiding face 122 of the dish sidewall 12. 
This achieves termination of the contact between the liquid stream in the 
dish 1 and the sheet in an exactly defined straight line extending at 
right angle with the direction of sheet-transportation, and at least 
greatly reduces the entrainment of liquid and air bubbles by the treated 
sheet. 
The asymmetrical gable-roof configuration of the lower guiding (bottom) 
surface of the passage-gap could also be designated as sawtooth-like 
profile. The transition zones or edges between the various profile faces 
can be rounded and the faces themselves need not be strictly planar. 
Generally, the profiling can be a kind of corrugation with flatter 
upstream-facing and steeper downstream-facing slopes. 
With regard to the operation of the apparatus, it will be understood that 
the sheets are gripped between the conveying and squeezing rollers 71 and 
72 and are pushed by the latter through the passage-gap D and then seized 
by the next-following rollers 73 and 74 and pulled by them. All roller 
pairs are driven absolutely synchronously.