Patent GB-926951-A (GB)
Title: Improvements in and relating to apparatus for applying liquid to sheet material
Inventor: NORMAN DAVID JOHN
IPC: G03D9/00
Filed: 1958-04-03
Abstract: Apparatus for applying liquid simultaneously to both sides of thin flexible photographic sheet material such as sensitized paper, or film, comprises co-operating applicator rollers 1, 2 at least one of which has a soft and yielding peripheral surface, said rollers being adapted and arranged to be driven so as to nip the sheet-material and move it downwards and a means whereby liquid can be transferred into the convergency formed by the said rollers above the nip so that in passing downwards between the said rollers the sheet material will be wetted on both sides and squeezed in the said nip, said surface of at least one of the rollers being sufficiently soft and yielding as to permit the passage of the sheet material between <PICT:0926951/III/1> <PICT:0926951/III/2> the rolls whilst maintaining a seal adjacent each edge of the sheet so that the sheet emerges in a relatively dry and flat condition without excessive wetting of the margins of the sheet. Transfer rolls may be employed, and where this is the case, the rolls are either continuously spaced from the periphery of the corresponding applicator roller, e.g. as described in Specification 698,080, or at intervals along the length of the rolls, e.g. by helical threads or ring projections on the transfer rolls.  As shown in Fig. 1, two rollers 1, 2 having a covering of relatively soft rubber are urged together and each dips into a shallow trough 3 containing a developing solution so that the sheet material can be passed downwards between the rollers and emerge through a slot 4 in the trough, the walls 5 of the slot rising above the normal level of the liquid in the trough.  The rollers pick up a certain amount of liquid from the trough and a small quantity thereof accumulates in the convergent space 6 produced by the rollers above the nip 7, the surplus running to the ends of the rollers and back into the trough. The sheet material passes through the nip and emerges in a fairly dry condition.  Baffles may be provided beneath each roller, and liquid-level control means may be provided.  In another embodiment, Fig. 2 (not shown), the rollers are each supplied with liquid by a separate transfer roll which each dip in a separate trough, the coated sheet passing downwardly between the troughs. The rollers 1, 2 are mounted on the ends of pairs of arms which are pivotable about the axis of the respective transfer roll.  The rollers 1, 2 may be spring-urged towards or away from each other, and the arms may be adjustable.  The transfer rolls may be positively driven and drive the rolls 1, 2 by friction or through gearing.  In another embodiment, Fig. 3 transfer rolls 28, 29 supply rollers 32, 33 with liquid, the roller 32 having a soft porous rubber cover 34 which may comprise rubber discs threaded on a core 33a, the journals 35 being displaceable in slots 36.  A support roller 38 and a displaceable weight roller 39 are provided, and the rolls 28, 29 have a helical thread T of nylon wound about them.  Specification 926,952 also is referred to.ALSO:Apparatus for applying liquid simultaneously to both sides of thin flexible photographic sheet material such as sensitized paper or film, comprises co-operating applicator rollers 1, 2 at least one of which has a soft and yielding peripheral surface, said rollers being adapted and arranged to be driven so as to nip the sheet material and move it downwards and a means whereby liquid can be transferred into the convergency formed by the said rollers above the nip so that in passing downwards between the said rollers the sheet material will be wetted on both sides and squeezed in the said nip, said surface of at least one of the rollers being sufficiently soft and yielding as to permit the passage of the sheet material between the rolls whilst maintaining a seal adjacent each edge of the sheet so that the sheet emerges in a relatively dry and flat condition without excessive wetting of the margins of the sheet. Transfer rolls may be employed, and where this is the case, the <PICT:0926951/IV(a)/1> <PICT:0926951/IV(a)/2> rolls are either continuously spaced from the periphery of the corresponding applicator roller, e.g. as described in Specification 698,080, or at intervals along the length of the rolls, e.g. by helical threads or ring projections on the transfer rolls.  As shown in Fig. 1, two rollers 1, 2, having a covering of relatively soft rubber are urged together and each dips into a shallow trough 3 containing a developing solution so that the sheet material can be passed downwards between the rollers and emerge through a slot 4 in the trough, the walls 5 of the slot rising above the normal level of the liquid in the trough.  The rollers pick up a certain amount of liquid from the trough and a small quantity thereof accumulates in the convergent space 6 produced by the rollers above the nip 7, the surplus running to the ends of the rollers and back into the trough. The sheet material passes through the nip and emerges in a fairly dry condition.  Baffles may be provided beneath each roller, and liquid-level control means may be provided.  In another embodiment, Fig. 2 (not shown), the rollers are each supplied with liquid by a separate transfer roll which each dip in a separate trough, the coated sheet passing downwardly between the troughs. The rollers 1, 2 are mounted on the ends of pairs of arms which are pivotable about the axis of the respective transfer roll. The rollers 1, 2 may be spring-urged towards or away from each other, and the arms may be adjustable.  The transfer rolls may be positively driven and drive the rolls 1, 2 by friction or through gearing.  In another embodiment, Fig. 3, transfer rolls 28, 29 supply rollers 32, 33 with liquid, the roller 32 having a soft porous rubber cover 34 which may comprise rubber discs threaded on a core 33a, the journals 35 being displaceable in slots 36.  A support roller 38 and a displaceable weight roller 39 are provided, and the rolls 28, 29 have a helical thread T of nylon wound about them.  Specification 926,952 also is referred to.