Field of the invention.
[0001] This invention relates to apparatus for the processing of exposed photographic material,
and in particular for apparatus for developing colour proofs, and a method of regeneration
of the process liquid used in such apparatus.
Background Technology
[0002] In the development of proofs particularly colour proofs the photographic plate will
pass through a development process in which the plate passes through in turn a developing
section, a fixing section, a wash section and a drying section. In the developing
and fixing sections a plate typically passes through a bath of process liquid. The
process liquid in the respective bath will degenerate due to chemical reaction with
the photographic material, and oxidation due to contact with the air. The process
liquid in the bath will drop in level due to carry-over on the photographic materials
and due to evaporation. It is therefore necessary to add fresh liquid to the bath.
This addition thus depends on the amount of processed material but it will be time-dependent
as well.
[0003] It is known to add fresh liquid to the bath by means of so-called chicken-feed bottles
that supply liquid as the liquid level in the bath lowers due to carry-over, but also
due to intentional removal of used liquid in order to cause spontaneous replacement
by fresh liquid for reasons of oxidation compensation. Such removal occurs by opening
a discharge valve in a bottom conduit of the tank, and the used liquid flows in a
waste collection vessel. A disadvantage of this system is premature oxidation of procesing
liquid in the bottle.
[0004] It is further known to carry out bath control by means of so-called cubitainers,
i.e. a collapsable plastic bag in a rectangular cardboard box, which is in connection
with a supply conduit through which liquid is withdrawn and pumped in the processing
station under the control of a level sensor in the station, and a return conduit via
which liquid can return to the cubitainer. The return conduit is normally closed by
a discharge valve. This valve is opened for certain periods to withdraw an amount
of liquid from the bath and automatically produce thereby its replacement by fresh
liquid, in order to compensate for oxidation of the bath. It has been shown that time-controlled
operation of this discharge valve, unlike the valve in a chicken-feed system comprising
a waste collection vessel, does not produce true time-dependent discharge rates because
the air pressure in the cubitainer fluctuates as a consequence of the air-tight connection
of the supply and return conduits to the cubitainer and of the changing volume of
the bag caused by a progressive removal of its contents to compensate for evaporation
and carry-over of processing liquid from the bath.
Object of invention
[0005] The present invention provides an apparatus for processing photographic material,
which includes a process bath filled with processing liquid and having discharge means
for discharging a given amount of processing liquid from the bath which operates more
accurately than known discharge means so that regeneration can be effected with improved
accuracy.
Statements of Invention
[0006] According to the invention there is provided apparatus for processing photographic
material and which includes at least one process bath, the or each bath in use being
filled with processing liquid held in a sealed collapsible container, a delivery pump
for removing liquid from said container and delivering it to said respective bath,
a respective sensor for determining when the liquid has reached a predetermined level
in said bath to control the delivery pump, and discharge means for removing predetermined
volumes of liquid from the bath and returning them to said container, which is characterized
in that said discharge means is formed by a volumetric pump in an exit of the bath.
[0007] The apparatus may have a second sensor means for monitoring the quantity of photographic
material processed in the bath and/or processor, said second sensor means also controlling
the discharge means.
[0008] The process bath may be for developing and/or fixing the photographic images on a
plate.
[0009] Also according to the invention there is provided a method of regenerating a process
liquid in a photographic development process in which photographic material passes
through a bath of said liquid, the liquid being fed to the bath to maintain the liquid
level therein at a predetermined level and used liquid being discharged from the bath
causing the new liquid to be fed to the bath to maintain said level, the process liquid
fed to the bath being provided in an enclosed collapsible container, and discharged
process liquid being received in said same collapsible container, characterised in
that the discharge of said liquid occurs under volumetric control.
[0010] Preferably, the process liquid when pumped from the container can cause the container
to collapse.
[0011] The invention will be described by way of example and with reference to the accompanying
drawing which is a schematic diagram of an apparatus according to the present invention.
Detailed description of the invention.
[0012] With reference to the drawing there is illustrated in schematic form a processor
10 for processing photographic material and in particular for producing off-press
colour proofs for accessing the quality of colour separations and colour rendition
in printing.
[0013] Only those features of the processor 10 relating to the present invention will be
described.
[0014] The photographic proof will in the course of its development pass through a liquid
developer which develops the silver image, a liquid fixer which removes silver from
the proof, a wash to remove non hardened parts and a drier. A proof will have to make
four such passes to build up a full colour picture.
[0015] The processor 10 has a housing 11 which encloses a first process bath 12 and a second
process bath 13. The first bath 12 is a development bath and the second bath 13 is
a fixing bath. The development bath, in particular, is as enclosed as possible to
prevent oxidation of the liquid developer in the bath 12.
[0016] Essentially the supply and regeneration of process liquid to both baths 12 and 13
is similar.
[0017] The process liquids are each supplied in a respective collapsible container 15. Containers
known as cubitainers which consist of a collapsible plastic cube inside a corrugated
outer board are suitable. The mouth 16 of each container is sealed by a cap (not shown)
through which a supply conduit 17 and a return conduit 18 pass. We refer to our co-pending
EP application N°93 203 182.6 entitled "A cap for a liquid storage container and apparatus
using such cap" wherein a particularly suitable cap system for a cubitainer is disclosed.
The process liquid is delivered to the respective bath 12 or 13 through the supply
conduit 17 by means of a delivery pump 19 located in the supply conduit between the
respective bath and container. The delivery pump 19 has a motor 22 connected to a
controller 21 which controls the operation of the pump. Each delivery pump 19 is preferably
a bellows type pump.
[0018] A liquid level sensor 23 monitors the presence of liquid in each bath 12 or 13 and
is connected to the controller 21 to cause the respective delivery pump 19 to supply
the respective process liquid to the bath until the liquid level therein has reached
a predetermined level. This will automatically compensate for loss of process liquid
caused by evaporation and carry over.
[0019] A discharge means in the form of an exit pump 25 is located in the return conduit
18 between each respective bath 12 or 13 and its container 15. Each exit pump 25 has
a motor 26 connected to the controller 21 for operation of the respective exit pump
25. Each exit pump 25 is preferably a peristaltic type pump which gives a good shut
off when the pump is inoperative. The controller 21 causes each exit pump 25 to operate
for a predetermined time period after predetermined time intervals so that used liquid
from the baths 12, 13 is regularly removed and returned to the respective container
15. This removes process liquid which may be degenerated due to both oxidation and
use. The time interval between operations of the exit pump, and/or the time period
for which the pump is operational may be controlled by a timer control 27.
[0020] The developing bath 12 may have a second sensor 31 which monitors the quantity of
photographic material passing through the processor 10. Such a sensor can be of a
type as described in EP Application 92 202 464.1. The second sensor 31 will additionally
cause the respective exit pump 25 to also operate after a predetermined quantity of
photographic material has passed through the processor 10, to compensate for developer
exhausted by chemical reaction with the photographic material.
[0021] Typically a collapsible container 15 will hold approximately 6 - 10 times more process
liquid than the bath. In this case the baths 12 & 13 have a capacity of about 3 litres
and the supply container 15 holds about 20 litres of process liquid. Since the containers
15 are sealed then the bulk of the process liquid at any given moment is prevented
from reacting with the surrounding atmosphere . This slows down the oxidation process.
[0022] The exit pumps 25 are caused to operate for 13 seconds per minute and have a pump
capacity of 300mls/min. The volume of the bath returned to the container, causes consequent
operation of the delivery pumps 19 under the control of level sensor 23 for regeneration
of the liquid in the respective bath by delivering the same volume of fluid as that
removed.
[0023] When the second sensor 31 triggers the exit pump 25 this may additionally operate
to remove a large quantity of liquid from the developing bath 12, and thereby also
cause regeneration of the bath contents.
[0024] With sealed collapsable containers 15 to minimize oxidation, the exit pumps 25 could
cause an increase in pressure within the containers. The bellows delivery pumps 19
allow the high pressure to defuse through the delivery pump. Alternatively pressure
sensitive safety valves could be provided.
[0025] Since the delivery pumps 19 remove more liquid from the containers 15 than is returned
thereto by the discharge pumps (because of evaporation and carry-over), the plastic
bag of the containers will progressively collapse, no air entering the container.
[0026] Whilst the invention has been described with reference specifically to developing
and fixing liquids, it will be apparent that the invention could be applied to regenerating
any process liquid utilised in photographic material processing, especially such liquids
which are liable to react with their surrounding atmosphere.
1. Apparatus for processing photographic material and which includes at least one process
bath (12 or 13), the or each bath (12 or 13) in use being filled with processing liquid
held in a sealed collapsible container (15), a delivery pump (19) for removing liquid
from said container (15) and delivering it to said respective bath, a respective sensor
(23) for determining when the liquid has reached a predetermined level in said bath
to control the delivery pump, and discharge means (25) for removing predetermined
volumes of liquid from the bath and returning them to said container, characterised
in that said discharge means is formed by a volumetric pump in an exit of the bath.
2. Apparatus according to claim 1, characterised in that it further includes a timer
control (27) which causes the discharge means (25) to operate for a determined period
of time at regular time intervals.
3. Apparatus according to claim 1 or 2, which includes a second sensor means (31) for
monitoring the quantity of photographic material processed in the bath and/or processor,
said sensor means (31) also controlling the discharge means (25).
4. Apparatus according to any of claims 1 to 3, wherein the apparatus includes a second
process bath (13).
5. A method of regenerating a process liquid in a photographic development process in
which photographic material passes through a bath (12 or 13) of said liquid, the liquid
being fed to the bath (13 or 13) to maintain the liquid level therein at a predetermined
level, and used liquid being discharged from the bath causing the new liquid to be
fed to the bath to maintain said level, the process liquid fed to the bath being provided
in an enclosed collapsible container (15), and discharged process liquid being received
in said same collapsible container, characterised in that the discharge of said liquid
occurs under volumetric control.
6. A method according to claim 5, characterised in that the ratio of the volume of the
bath to the container is in the ratio of 1:6 to 10 and about 2% of the bath content
is returned to the container per minute.
7. A method as claimed in claim 5 or 6, characterised in that liquid is also removed
from the bath after a predetermined quantity of photographic material has passed through
the bath.