EP0006799B1 - Process and device to improve the developing speed in a diazocopy apparatus - Google Patents

Abstract

The invention relates to an improvement in diazocopy development machines. A development chamber is used in which ammonia vapors are generated. A converging system made up of converging walls which accelerate the hot ammonia vapors, without additional means, channels the vapors toward the copy support. Thus, a striking is made of the support with the vapors and the development speed can be significantly increased.

Description

The present invention relates to an improvement to the process for developing diazocopies using ammonia vapors. It relates more particularly to a process for developing a copy medium coated with a sensitive diazo layer previously exposed through an original in an ultraviolet exposure station, consisting in bringing said copy medium into contact with ammonia vapors, at temperature greater than or equal to 55 ° C.

Such a process for developing diazocopies has been known for a long time under the name of "dry" development process.

Such a process is for example described in French patent application n ° 71 21 408 filed on July 13, 1976 in the name of the Applicant. In this patent, an improvement to the prior art is described which consists in particular in heating the back of the copy in order to obtain a better development of the latter in contact with ammoniacal vapors.

It is also known, in this development process, to achieve an overpressure of the ammonia vapors in the development chamber so as to increase the penetration of the ammonia vapors into the copy medium and thus accelerate the development of the sensitive layer. This overpressure is generally created either by a pump or by a fan.

The disadvantage of such a method is that the overpressure thus created requires controlling the leaks at the level of the development chamber so that said overpressure actually exists in said development chamber.

For this, it is necessary to provide additional means which can be very large and very costly, given the relative simplicity of the usual plan drawing machines. In addition, this overpressure being exerted by a pump or a fan, this creates additional energy consumption as well as a higher production cost.

The method according to the invention makes it possible to avoid these drawbacks.

To this end, the method according to the invention is characterized in that the ammoniacal vapors are channeled and accelerated vertically by aerodynamic effect in a convergent pipe, without supply of external energy to accelerate their ascent, said vapors then being directed towards the support of copy arranged in such a way that the flow of ammonia vapors has a trajectory between the horizontal and the vertical and strikes the copy medium, aside its sensitive layer, with a speed sufficient to cause rapid development of said copy medium.

Such a method is indeed particularly simple and does not require any device consuming energy for its realization.

The invention uses the "chimney effect" which produces a natural acceleration of the vapors which are concentrated in a convergent pipe: the vapors being hot, they undergo a natural acceleration allowing them to strike the copy medium and to penetrate into it ci, thus accelerating the speed of development of the sensitive layer.

So that the ammonia vapors arrive on the copy medium with a sufficient speed, an angle of incidence of said vapors on said medium will be chosen less than 45 ° and preferably at 30 °, in order also to obtain turbulence in the ammoniacal vapors close to the copy.

The invention also relates to a device for implementing such a method, said device comprising a developing chamber in which ammoniacal vapors are generated by means known per se, and a rotary cylinder bringing the sensitive layer of the copy in contact with said ammonia vapors, the device being characterized in that said development chamber comprises a convergent system for accelerating the ammonia vapors and concentrating them on the sensitive layer of the copy, said convergent system comprising no means of energy supply outside. By convergent system is meant a set of planes assembled together and having an upper opening and a lower opening, at least one dimension being identical for each of said planes and of which a section in a vertical plane perpendicular to the copy medium has an opening upper, of dimension smaller than that of the lower opening.

Preferably, a convergent system will be used consisting of two converging walls substantially parallel to the rotary cylinder, extending over the entire width of the developing chamber, the lower ends of each of said walls being arranged on either side of the cup. so as to channel the vapors released, while the upper ends of said walls are located near the rotary cylinder, the distance separating the bases from the walls being greater than the distance separating the top of said walls.

To ensure good efficiency in said system, that is to say not to slow the rise of ammoniacal vapors, it is important that the walls, which may consist of successive planes inclined with respect to each other, have no acute angle capable of reflecting part of said vapor.

• Le dispositif de développement comporte des joues latérales 21 formant supports entre lesquelles se trouve la chambre de développement 1 dont le fond forme une coupelle horizontale 9 à côté de laquelle est fixée la résistance chauffante 3. Le cylindre 6 qui est un tube métallique, par exemple, comporte suivant son axe une résistance chauffante 4. Il est muni d'un revêtement 5 qui est au contact de la paroi perforée 17 fixée en 18 et 19 par un moyen de type connu quelconque. L'étanchéité de la chambre de développement 1 est assurée par les joints à lèvre 8 et 15. La partie supérieure 12 de la chambre de développement 1 comporte une ouverture 27 munie d'un rebord autour duquel se fixe des conduits d'évacuation. Le matériau photosensible 42 à développer est introduit dans le dispositif de développement à l'aide d'un ensemble de sangles parallèles 35 entraînées par les rouleaux 33 et 34, lesdites sangles ayant une largeur d'environ 5 cm. Ces sangles sont espacées les unes des autres de quelques millimètres de sorte que peuvent prendre place entre-elles, des dents 29 ayant une extrémité semi-circulaire, fixées entre-elles par un support 30 de façon à former un peigne. La partie plane de ces dents 29 se trouve sous le guide supérieur 16 d'introduction du matériau photosensible 42, la partie semi-circulaire de ces dents permettant le retournement du matériau photosensible avant son introduction dans la chambre de développement.

The invention will be better understood using the following embodiment given as nonlimiting, together with the figure which represents a developer section according to the invention:

• The development device comprises lateral cheeks 21 forming supports between which is the development chamber 1, the bottom of which forms a horizontal cup 9 next to which the heating resistor 3 is fixed. The cylinder 6 which is a metal tube, for example , has along its axis a heating resistor 4. It is provided with a coating 5 which is in contact with the perforated wall 17 fixed at 18 and 19 by means of any known type. The sealing of the developing chamber 1 is ensured by the lip seals 8 and 15. The upper part 12 of the developing chamber 1 has an opening 27 provided with a flange around which the evacuation conduits are fixed. The photosensitive material 42 to be developed is introduced into the development device using a set of parallel straps 35 driven by the rollers 33 and 34, said straps having a width of approximately 5 cm. These straps are spaced from each other by a few millimeters so that can take place therebetween, teeth 29 having a semi-circular end, fixed together by a support 30 so as to form a comb. The flat part of these teeth 29 is located under the upper guide 16 for introducing the photosensitive material 42, the semi-circular part of these teeth allowing the photosensitive material to be turned over before its introduction into the development chamber.

The cylinder 6 has a toothed tip at each of its ends. Each of them is carried by three rollers 22, 23 and 24. The cylinder 6 is driven by the pinion 32 directly connected to the axis of a motor, not shown in the figure.

The thermostat 38, connected in series with the resistor 4 is placed near the internal wall of the cylinder 6. The thermostat 37 is connected in series with the heating resistors 2 and 3 placed respectively near the outlet of the developing chamber 1 and near the horizontal cup 9 and the introduction guide 16. As shown in the figure, the thermostat 37 is placed near the resistor 3 and the horizontal cup 9. In order to favor regulation of the temperature of the chamber development 1, it is surrounded by a material 20 with high thermal insulation power.

This material can be glass wool, polyurethane foam, expanded polystyrene, etc. Its thickness will be a few centimeters, varying depending on the material used.

The ascending system according to the present invention consists of a set of "rear" walls 51, 52 and 53 arranged parallel to the axis of rotation of the cylinder 6, and a set of "front" walls 54, 55, 56 and 57 arranged also parallel to cylinder 6.

• La vitesse maximum de développement d'une machine est la vitesse à laquelle on peut développer un papier diazoîque non insolé, sur une longueur déterminée, sans voir apparaître des zones mal développées.

These two sets of walls are interconnected by spacers such as 58 (three spacers are sufficient for a developer width of 1.25 m and aluminum walls). The walls are convergent, that is to say that the walls 53 and 54, near the cylinder are closer than the walls 51 and 57 located above the horizontal cup 9. It has been found that there is no was not necessary to have a tightness of this converging system. In particular, the wall 57 is located at a few distances (about 1 cm to facilitate manufacture) of the seal 15. Due to the suction of the ammonia vapors by a "chimney effect", it can be seen that very few vapors are directed to the copy support between the wall 57 and the joint 15. Furthermore, the angles between the walls 51, 52 and 53 are opto angles, as are those between the walls 54, 55, 56 and 57. The improvement development speed can be demonstrated by the following comparative experience:

• The maximum speed of development of a machine is the speed at which a non-insulated diazo paper can be developed, over a determined length, without seeing poorly developed zones appear.

Using a REGMA A 130 machine and also 9 N REGMA brand paper, width 1 10 cm, a speed limit of 350 m / hour is obtained for a length of 3 m.

On the same machine, a converging system is mounted as described above, the flow of ammonia vapors having an angle of incidence of about 25 ° relative to the drive cylinder.

We then obtain for a length of 3 m a speed limit of 450 m / hour (all other things being equal). It is obvious that the method according to the invention applies to all ammonia development machines with or without a copy support drive cylinder: this drive means can be arbitrary without departing from the scope of the invention. 'invention.

Claims (8)

1. Process for developing a copying base coated with a sensitive diazo layer exposed beforehand through an original in an ultraviolet exposure station, consisting in bringing the said copying base into contact with ammoniacal vapours at a temperature which is greater than or equal to 55°C, characterised in that the ammoniacal vapours are channelled and accelerated upwards by an aerodynamic effect in a convergent pipe, without supplying external energy for accelerating their upward motion, the said vapours being subsequently directed towards the copying base, the latter being arranged so that the stream of ammoniacal vapours has a trajectory between the horizontal and the vertical and impinges on the copying base, on the side where its sensitive layer is located, with a sufficient velocity to cause rapid developing of the said copying base.

2. Process according to Claim 1, characterised in that the stream of ammoniacal vapours is directed towards the copying base with an angle-of incidence which is substantially less than or equal to 45°.

3. Process according to Claim 1, characterised in that the stream of ammoniacal vapours is directed towards the copying base with an angle of incidence which is substantially less than or equal to 30°, so that the stream of reflected vapours creates a turbulence in the ammoniacal vapours present in the developer, so as to improve the developing of the copy.

4. Developing process according to one of Claims 1 to 3, characterised in that the copying base is heated on the back to a temperature above 55°C.

5. Device for carrying out the process according to one of Claims 1 to 4, comprising a developing chamber in which ammoniacal vapours are generated by means which are in themselves known, and a rotary cylinder which brings the sensitive layer of the copy into contact with the said ammoniacal vapours, characterised in that the said developing chamber comprises a convergent system for accelerating the ammoniacal vapours and concentrating them on the sensitive layer of the copy, the said convergent system not comprising any means of supplying external energy.

6. Device according to Claim 5, in which the ammoniacal solution is brought into a cup and vaporised into the developing chamber, characterised in that the convergent system consists of two convergent walls approximately parallel to the cylinder, extending over the whole width of the developing chamber, the lower ends of each of the said walls being arranged on either side of the cup so as to channel the vapours released, whilst the upper ends of the said walls are located near the rotary cylinder, the distance separating the bases of the walls being greater than the distance separating the top of the said walls.

7. Device according to one of Claims 5 or 6, characterised in that the convergent walls are directed towards the rotary cylinder with an angle of incidence which is less than or equal to about 45°.

8. Device according to one of Claims 5 to 7, characterised in that each of the walls is formed by a series of inclined planes, each plane forming an obtuse angle with the following plane.

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