EP0006799A1 - Process and device to improve the developing speed in a diazocopy apparatus - Google Patents

Abstract

In a diaocopying machine, in the developing chamber (1) where the ammonia vapors are generated, an ascending system consisting of a set of “rear” walls (51), (52) and (53) is used, and a set of “front” walls (54), (55), (56) and (57). Said vapors from the cup (9) are thus accelerated, without any external energy supply, and channeled in the direction of the copy support which moves between the perforated wall (17) and the coating (5) of the rotary cylinder (6) . The angle of incidence of the ammonia vapors on the support of the copies is less than 45 ° and preferably less than or equal to 30 °.

Description

The present invention relates to an improvement to the process for developing diazocopies using ammonia vapors or the like. 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 a 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 No. 76 2I 408 filed on July 13, I976 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 means which can be very large and very expensive, 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 disadvantages.

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, said vapors then being directed towards the copy medium. Arranged so that the flow of ammonia vapors has a trajectory between the horizontal and the vertical and strikes the copy medium, on the side of its sensitive layer, with a speed sufficient to cause rapid development of said copy medium.

Such a process is in fact particularly simple and does not require any device consuming energy for its implementation.

The invention uses the "chimney effect" which produces a natural acceleration of the vapors which are concentrated in a converging 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 development chamber in which ammonia vapors are generated by means known per se, and a rotary cylinder bringing the sensitive layer of the copy into contact with said ammonia vapors, the device being characterized in that said development chamber comprises a convergent system for accelerate the ammonia vapors and concentrate them on the sensitive layer of the copy, said convergent system comprising no means of external energy supply. 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 of 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.

The invention will be better understood with the aid of the following embodiment given without implied limitation, together with the figure which represents a section of developer according to the invention:

The development device comprises lateral cheeks 2I forming supports between which is the development chamber I, 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 I7 fixed at I8 and I9 by means of any known type. The development chamber I is ensured by the lip seals 8 and I5. The upper part I2 of the development chamber I comprises an opening 27 provided with a flange around which is fixed evacuation conduits. 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 between them by a support 30 so as to form a comb. The flat part of these teeth 29 is located under the upper guide I6 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 inner wall of the double cylinder 6.

Thermostat 37 is connected in series - with heating resistors 2 and 3 placed respectively near the exit from the developing chamber I and near the horizontal cup 9 and the introduction guide I6. As shown in the figure, the thermostat 37 is placed near the resistor 3 and the horizontal cup 9. In order to favor the regulation of the temperature of the developing chamber I, the latter is surrounded by a material 20 to strong thermal insulation power.

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

The ascending system according to the present invention consists of a set of "rear" walls 5I, 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.

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 5I and 57 situated 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 a few distances (approximately I cm to facilitate manufacture) from the joint I5. Due to the suction of the ammonia vapors by a "chimney effect", it can be seen that very few vapors are directed towards the copy support between the wall 57 and the seal I5. Furthermore, the angles between the walls 5I, 52 and 53 are optus angles, as well as those between the walls 54, 55, 56 and 57. The improvement in the speed of development can be demonstrated by experience following comparison:

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 areas appear.

Using a REGMA A I30 machine and also 9 N REGMA brand paper, 110 cm wide, 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 (7)

I - Method for developing a copy support coated with a diazo sensitive layer, previously exposed through an original in an ultraviolet exposure station, consisting in bringing said copy support in contact with ammonia vapors at higher temperature or equal to 55 ° C, characterized in that the ammonia vapors are channeled and accelerated upwards by aerodynamic effect in a convergent pipe, without any external energy supply to accelerate their ascent, said vapors then being directed towards the copy medium 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, on the side of its sensitive layer, with a speed sufficient to cause rapid development of said copy medium. 2 - Method according to claim I, characterized in that the flow of ammonia vapors is directed towards the copy medium with an angle of incidence substantially less than or equal to 45 °. 3 - Method according to claim I, characterized in that the flow of ammonia vapors is directed towards the copy medium with an angle of incidence substantially less than or equal to 30 °, so that the flow of reflected vapors creates turbulence in the ammonia vapors present in the developer, so as to improve the development of the copy. 4 - Development method according to one of claims I to 3, characterized in that the copy medium is heated on the back to a temperature above 55 ° C. 5 - Device for implementing the method according to one of claims I to 4, comprising a developing chamber in which are generated ammonia vapors by means known per se, and a rotary cylinder bringing the sensitive layer of the copy in contact with said ammonia vapors, 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 supplying external energy. 6 - Device according to claim 5, wherein the ammonia solution is brought into a cup and vaporized in the development chamber, characterized in that the converging system consists of two converging walls substantially parallel to the rotary cylinder, extending over any the 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 apex from said walls. 7 - Device according to one of claims 5 or 6, characterized in that the converging walls are oriented towards the rotary cylinder with an angle of incidence less than or equal to about 45 °. 8 - Device according to one of claims 5 to 7, characterized in that each of the walls is formed of a succession of inclined planes, each plane making an obtuse angle with the next plane.

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