GB1584178A - Diazo type developing method and apparatus - Google Patents

Description

(54) DIAZO TYPE DEVELOPING METHOD AND APPARATUS (71) We, MICROBOXDR. WELP GMBH & Co., a company organised under the laws of the Federal Republic of Germany, of Salinenstrasse 52, D-6350 Bad Nauheim, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to a method and apparatus for developing an exposed diazo film in which ammonia gas is used.

It is known in this art to duplicate silver film onto a diazo duplicate film employing the principle of heliographic or so-called blueprint copying machines, whereby the duplicating film is exposed and thereafter developed in ammonia gas. The ammonia gas is produced by evaporating of ammonia water or ammonia crystals. This type of prior art method requires for its performance a substantial length of time.

It is further known to develop the diazofilm in the course of the prior art blueprinting under a high gas pressure, for example, six atmospheres gauge pressure.

Due to the pressure application the development time is reduced so that one duplicate copy may be made per second.

The gas required for the performance of the prior art methods in producing the high pressure is obtained from commercially available gas bottles which are returned for a refill when their content is used up.

Another disadvantage of the prior art development method is seen in that the ammonia gas which has not been used up and which escapes when the developing chamber is opened must either be suckedoff or it must be collected in a container holding an absorber liquid. The installation of equipment for sucking off the ammonia gas not used up, is cumbersome. The frequent changing of the absorber liquid is expensive.

The present method and apparatus may use ammonia water which is readily available and the ammonia gas derived from the ammonia water is circulated in a closed circuit so that the operation is more economical than heretofore.

According to the invention there is provided a method of developing an exposed diazofilm by means of ammonia gas comprising the steps of heating an aqueous solution of ammonia in a closed container to produce ammonia vapour, sucking the vapour from the container, compressing the vapour, and delivering it to a developing chamber for development of a film therein, and returning the vapour to the container after development, in a closed circuit.

According to the invention there is further provided an apparatus for developing an exposed diazofilm by means of ammonia gas comprising a container for aqueous ammonia solution, means for heating a solution in the container, means for the suction of ammonia vapour from the container and the compression thereof, a developing chamber conduit means connecting the container, the suction and compression means, and the chamber to form a closed circuit system, and valve means between the container and the suction and compression means, between the container and the chamber, and between the suction and the compression means and the chamber, and valve means being operable so that the suction and compression means may deliver compressed ammonia vapour from the container to the chamber for development of a film therein, and after development the vapour may be returned to the container.

In order that the invention may be clearly understood, it will now be described, by way of example, with reference to the accompanying drawing which illustrates a block diagram of the present apparatus including the closed flow circuit for the ammonia gas.

The duplicating or copied card or sheet 1 is exposed through a suitable original.

The original may be a silver film or another diazofilm similar to the duplicated copy or sheet 1. The copy 1 is inserted into the developing chamber 2 either by hand or automatically as is known in the art. When the copy 1 is inserted into the developing chamber 2 the latter is closed by moving the bottom plate 3 against the top portion 18 of the developing chamber 2. The chamber 2 is sealed by a sealing ring 19 when the bottom plate 3 presses against the top portion 18 by means not shown but capable of moving the bottom plate 3 up and down.

The closed circuit system further comprises a supply container 7 for the ammonia in the form of ammonia water 6 in the container 7 which is heatable by a heater (not shown), such as heating coils or the like known as such.

The closed circuit system further includes a piston cylinder arrangement 21 including a piston 4 movable up and down by conventional means as shown by the arrow.

First conduit means 8 connect an outlet port of the container 7 to an inlet port of the cylinder 22 through a valve 9. Second conduit means 15 connect the developing chamber 2 to an outlet port of the cylinder chamber 10, again through a valve 11.

Third conduit means 17 interconnect the developing chamber 2 to an inlet port of the container 7 through a valve 16, thereby completing the closed circuit.

An evacuating device 13, for instance, evacuable by a conventional pump is operatively connected to the developing chamber 2 by a fourth conduit 14 including a valve 12. Incidentally, the developing chamber 2 is also heatable by a conventional heater (not shown). Preferably, the chamber 2 with its top portion 18 is stationary and the bottom plate 3 is movable.

In operation, when the piston 4 in the chamber 10 moves downwardly, ammonia gas is sucked through the conduit 8 into the chamber 10 of the compressor which is shown as a piston cylinder arrangement 21.

The container 7 which is heatable, is substantially evacuated and filled to about 750/u with ammonia water 6. If the stroke of the piston 4 is completed downwardly, the valve 9 is closed. The control of the valve 9 may be accomplished in any suitable, conventional manner, for example, by magnetic means responsive to the piston movement.

During the suction stroke of the piston 4, the valve 12 is temporarily opened for a short period of time, whereby the continuously evacuated container 13 substantially evacuates the developing chamber 2 through the conduit 14 and said valve 12.

If the piston 4 now moves upwardly, while the valve 9 is closed, it compresses the anionia gas sucked into the pump chamber 10 and, after opening to the valve 11 the ammonia gas is supplied into the develop ing chamber 2 under pressure through the conduit 15 and the valve 11. When the piston 4 completes its upward stroke, the valve 11 is closed, again by conventional means. When the time duration for the developing is completed, the valve 16 is opened in the conduit 17 between the developing chamber 2 and the supply container 7, whereby the ammonia gas under pressure in the developing chamber 2 is expanded. Subsequent to the expansion the vacuum 5 in the container 7 sucks the remaining ammonia gas out of the developing chamber 2, whereupon the valve 16 is closed again and the plate 3 moves downwardly so that the duplicate card or copy 1 may be removed from the developing chamber 2. Such removal may be accomplished automatically.

Thereafter the valve 9 is opened again and the apparatus is in its starting position so that the work cycle may be repeatecl for a further copy of duplicate card 1.

Advantages of the invention are seen in that it is now possible to use ammonia water for obtaining the ammonia gas necessary for the developing of diazofilms.

Such ammonia water is readily available, for example, in a solution comprising about 75% H2O and about 25% NH3.

The compression of the ammonia gas involves a relatively high pressure of, for example, six atmospheres gauge pressure whereby simultaneously the compressed gas is heated by the heater 23 resulting in a rapid development of the diazofilms, for example, the development time according to the invention is about one second per copy.

By maintaining the ammonia gas in a closed circuit system it is possible to retrieve the ammonia gas which is not used up in the developing process, by returning it into the container 7 holding the ammonia water, whereby an optimal utilization of the NH, is accomplished. For example, it should be mentioned here that from about 3503cm of ammonia water an equal number of cm3 of NH3 may be obtained which is comparable to the ammonia supply from a bottle containing 0.9 kg liquified ammonia. The method according to the invention is thus much more economical as far as the use of NH, is concerned, whereby substantial savings as compared to the prior art are ac complished. Another advantage is seen iii that no odor development is present in the environment where an apparatus according to the present invention is operated. More over, a sucking off or removing of the gasses into an absorption means is also obviated according to the invention.

The developing chamber is preferably evacuated prior to the entry of ammonia gas into the developing chamber. It is further preferable to heat the ammonia gas in the developing chamber. Such heating should bring the temperature of the ammonia gas to a value within the range of about 30 "C to about 60 "C.

It is an advantage that obnoxious odors are avoided by the present method and apparatus. Further, sucking off ammonia gas and the use of an absorbtion means for the ammonia gas are also avoided.

In view of the foregoing, it will be appreciated that the invention is not limited to duplicating from a silver film original onto a diazo copy film because it is possible without difficulties to copy from one diazofilm original to another diazofilm WHAT WE CLAIM IS: 1. A method of developing an exposed diazofilm by means of ammonia gas comprising the steps of heating an aqueous solution of ammonia in a closed container to produce ammonia vapour, sucking the vapour from the container, compressing the vapour, and delivering it to a developing chamber for development of a film therein, and returning the vapour to the container after development, in a closed circuit.

2. A method according to claim 1, further comprising evacuating said developing chamber prior to delivering ammonia gas into said developing chamber.

3. A method according to claim 2, wherein said evacuation provides a vacuum within the gauge pressure range of -0.3 to -0.6 bar.

4. A method according to any of claims 1-3, wherein the ammonia gas in the developing chamber is at a temperature within the range of 30 "C to 60 "C.

5. A method according to any claims 1-4, wherein the ammonia in the container is heated to a temperature within the range of 30 "C to 60 "C.

6. Apparatus for developing an exposed diazofilm by means of ammonia gas comprising a container for aqueous ammonia solution, means for heating a solution in the container, means for the suction of ammonia vapour from the container and the compression thereof, a developing chamber conduit means connecting the container, the suction and compression means, and the chamber to form a closed circuit system, and valve means between the container and the suction and compression means, between the container and the chamber, and between the suction and the compression and means and the chamber, and valve means being operable so that the suction and compression means may deliver compressed ammonia vapour from the container to the chamber for development of a film therein, and after development the vapour may be returned to the container.

7. Apparatus according to claim 6 including means for evacuating the chamber, and valve means in conduit means between the chamber and the evacuating means.

8. A method of developing an exposed diazofilm substantially as hereinbefore described with reference to the accompanying drawing.

9. An apparatus for developing an exposed diazofilm constructed and arranged substantially as described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. evacuated prior to the entry of ammonia gas into the developing chamber. It is further preferable to heat the ammonia gas in the developing chamber. Such heating should bring the temperature of the ammonia gas to a value within the range of about 30 "C to about 60 "C. It is an advantage that obnoxious odors are avoided by the present method and apparatus. Further, sucking off ammonia gas and the use of an absorbtion means for the ammonia gas are also avoided. In view of the foregoing, it will be appreciated that the invention is not limited to duplicating from a silver film original onto a diazo copy film because it is possible without difficulties to copy from one diazofilm original to another diazofilm WHAT WE CLAIM IS:

1. A method of developing an exposed diazofilm by means of ammonia gas comprising the steps of heating an aqueous solution of ammonia in a closed container to produce ammonia vapour, sucking the vapour from the container, compressing the vapour, and delivering it to a developing chamber for development of a film therein, and returning the vapour to the container after development, in a closed circuit.

2. A method according to claim 1, further comprising evacuating said developing chamber prior to delivering ammonia gas into said developing chamber.

3. A method according to claim 2, wherein said evacuation provides a vacuum within the gauge pressure range of -0.3 to -0.6 bar.

4. A method according to any of claims 1-3, wherein the ammonia gas in the developing chamber is at a temperature within the range of 30 "C to 60 "C.

5. A method according to any claims 1-4, wherein the ammonia in the container is heated to a temperature within the range of 30 "C to 60 "C.

6. Apparatus for developing an exposed diazofilm by means of ammonia gas comprising a container for aqueous ammonia solution, means for heating a solution in the container, means for the suction of ammonia vapour from the container and the compression thereof, a developing chamber conduit means connecting the container, the suction and compression means, and the chamber to form a closed circuit system, and valve means between the container and the suction and compression means, between the container and the chamber, and between the suction and the compression and means and the chamber, and valve means being operable so that the suction and compression means may deliver compressed ammonia vapour from the container to the chamber for development of a film therein, and after development the vapour may be returned to the container.

7. Apparatus according to claim 6 including means for evacuating the chamber, and valve means in conduit means between the chamber and the evacuating means.

8. A method of developing an exposed diazofilm substantially as hereinbefore described with reference to the accompanying drawing.

9. An apparatus for developing an exposed diazofilm constructed and arranged substantially as described with reference to the accompanying drawing.