EP0005405B1 - Apparatus for the destruction of microfilms - Google Patents

Abstract

Microfiches to be destroyed by heat treatment are placed within a disposable tube fitted with a sealing plug, then baked to a sufficient temperature to cause melting and discarded. The apparatus comprises an electric heating resistor and a tubular heating jacket for receiving the disposable tube, the sealing plug being forcibly engaged in the tube by means of a cap which is screwed down by hand. All negative sheets and documents having a photosensitive surface such as microfiches are destroyed economically without any contaminating waste products.

Description

The present invention relates to an apparatus for destroying microfiches comprising a photosensitive support intended to receive information in particular of accounting nature. These microfiche must be destroyed after use for reasons of confidentiality.

Among the methods for destroying microfiches, we know those which proceed by grinding and shredding into fine particles or by chemical attack. The devices in which this destruction is carried out are expensive, which does not allow them to be used profitably when the number of microfiches to be destroyed daily is low. Also known, in particular according to French patent A-2 294 469, is an apparatus using a heat source which destroys the photosensitive layer of the microfiches which thus become transparent when they are scrolled past this heat source. Such an apparatus is however not suitable for the destruction of microfiches of varied nature. In addition, this device is relatively bulky and inconvenient to use, in particular as regards the placement of microfiches inside the device and the evacuation of destroyed microfiches.

The present invention aims to allow safe and economical destruction of microfiches, whatever their composition, without causing the creation of polluting waste.

Laboratory ovens are also known (see for example DE-B-1 294 600) comprising a vertical tubular envelope fixed on a base and surrounded by a heating resistor. However, these ovens by design are not suitable for the destruction of microfiche.

Also known are autoclave tubes comprising removable and sealed caps intended to be placed vertically inside an adjustable and automatic oven (Glas und Instrumenten-Technik, vol. 14, n ° 4, April 1980, p. 352) and which, therefore, are not provided with integrated heating means. Such devices are also not suitable for destroying microfiche.

The apparatus targeted by the invention for the destruction of microfiches, comprises a vertical tubular envelope fixed on a base and surrounded by a heating resistor. According to the invention, this device is characterized in that inside the tubular casing is removably accommodated a tube provided with a stopper, made of a material resistant to temperatures of the order of 200 to 250 ° C, this tube having an internal diameter adapted to receive one or more microfiches wound one on the other along the axis of the tube and in that the apparatus comprises means for ensuring a substantially sealed closure of the tube by its cap for cooking microfiches.

Experience has shown that this device can be used to obtain complete destruction of the microfiches by fusion and solidification, transforming the bundle of microfiches into an indecipherable compact block which can be thrown away with the tube. This device can have a very small dimension and a low electrical power thanks to the excellent efficiency of the heat transfer between the heating resistors and the microfiches whose surface is in intimate contact with the wall of the tube.

Other features of the invention will also result from the description below.

• - la figure 1 est une vue schématique en élévation après coupe axiale du corps d'un appareil conforme à l'invention;
• - la figure 2 est la vue en coupe axiale d'un tube jetable pour l'appareil de la figure 1;
• -la figure 3 est la vue en coupe axiale de l'appareil en cours de fonctionnement;
• - la figure 4 est un schéma simplifié en section droite d'une variante;
• - la figure 5 est une vue en coupe axiale d'une autre réalisation de l'appareil;
• - la figure 6 est une vue de détail de l'appareil précédent, suivant VI de la figure 5.

In the appended drawings, given by way of nonlimiting examples:

• - Figure 1 is a schematic elevational view after axial section of the body of an apparatus according to the invention;
• - Figure 2 is the axial sectional view of a disposable tube for the apparatus of Figure 1;
• FIG. 3 is the view in axial section of the device during operation;
• - Figure 4 is a simplified diagram in cross section of a variant;
• - Figure 5 is an axial sectional view of another embodiment of the apparatus;
• FIG. 6 is a detailed view of the preceding apparatus, along VI of FIG. 5.

With reference to the accompanying drawings, the process covered by the invention will be described in the context of the operation of an apparatus allowing its implementation.

This device essentially comprises a heating tubular casing 1 fixed to a base 2 by a screw 3, this casing 1 thus being kept vertical in the service position.

The casing 1 comprises a cylindrical outer wall 4 which surrounds a tubular insulating wall 5 providing inside an axial housing 6. The inner surface of the wall 5 is provided with a flexible electric heating resistor 7, wound helically.

The bottom of the casing 1 is provided with a return spring 8 and the upper periphery 4a of the wall 4 is threaded to receive a metal cap 9 intended to be screwed by means of an attached handle 11, made of insulating material, which is thermally insulated from the cap 9, but is made integral with the latter by connecting screws 12.

• - mise en température de l'enveloppe 1 et phase de cuisson. Cette phase est signalée par deux voyants lumineux 16, 17;
• - commande du temps de refroidissement, signalé par le seul voyant 17;
• - fin de l'opération signalée par l'extinction des deux voyants et l'actionnement d'un avertisseur sonore schématisé en 18.

The assembly thus formed is housed in an outer cylindrical body 13, for example of plastic, coaxial with the casing 1 and which surrounds it at a certain distance. The body 14 carries a plate 15 on which is formed a printed circuit constituting an electronic programmer, or timer 20 ensuring the succession of the following operations:

• - heating of the envelope 1 and cooking phase. This phase is signaled by two indicator lights 16, 17;
• - control of the cooling time, signaled by the only indicator 17;
• - end of the operation signaled by the extinction of the two warning lights and the actuation of an audible warning shown diagrammatically in 18.

The power is supplied by the conductors 19 which terminate in a push button switch 21. We also see at 22 the conductors serving the heating resistor 7 and whose supply is controlled by the programmer 20.

To the device thus constituted is added (FIG. 2) a disposable tube 25 for example of very inexpensive spun aluminum and provided with a plug 26 mounted frictionally, of the same material. The tube 25 has dimensions such that it can receive, for example, up to six microfiches rolled together along the axis of the tube.

Furthermore, the outside diameter of the tube 25 corresponds to the inside diameter of the insulating wall 5 and its height, after fitting the plug 26, is greater than that of the wall 4. For example, for the destruction of five with six microfiches, one can provide a disposable tube 25 millimeters in diameter, 125 millimeters high in extruded aluminum 0.3 millimeters thick.

• - Lorsque l'utilisateur a rassemblé le nombre voulu de microfiches 30 à détruire pour remplir le tube 25, il les roule les unes sur les autres, les enfile dans le tube et ferme celui-ci avec le bouchon 26 enfoncé à force. Le tube 25 est mis en place dans le logement 6 de l'enveloppe chauffante 1, puis la coiffe 9 est vissée sur le filetage 4a de la paroi 4 en s'aidant de la poignée 11. Ce faisant, on enfonce le tube 25 dans le logement 6 en comprimant le ressort 8 (figure 3).
• - L'utilisateur appuie ensuite sur le bouton-poussoir du contacteur 21, ce qui met sous tension la résistance de chauffage 7. L'intérieur du tube 25 est alors porté très rapidement à une température de cuisson suffisante pour fondre la matière photosensible des microfiches 30. Cette cuisson a lieu en atmosphère close, le bouchage du tube 25 étant hermétique grâce à la friction s'opposant à la sortie du bouchon 26 et aux actions conjuguées de la coiffe 9 et du ressort antagoniste 8 qui s'opposent à toute ouverture du tube 25 sous la pression des gaz dégagés par la cuisson.

The implementation of the apparatus thus constituted for the application of the method covered by the invention is as follows:

• - When the user has gathered the desired number of microfiches 30 to destroy in order to fill the tube 25, he rolls them one on top of the other, puts them in the tube and closes it with the plug 26 forcibly inserted. The tube 25 is put in place in the housing 6 of the heating jacket 1, then the cap 9 is screwed onto the thread 4a of the wall 4 using the handle 11. In doing so, the tube 25 is pushed into the housing 6 by compressing the spring 8 (Figure 3).
• - The user then presses the push button of the contactor 21, which energizes the heating resistor 7. The interior of the tube 25 is then brought very quickly to a cooking temperature sufficient to melt the photosensitive material of the microfiches 30. This cooking takes place in a closed atmosphere, the plugging of the tube 25 being hermetic thanks to the friction opposing the outlet of the plug 26 and to the combined actions of the cap 9 and the opposing spring 8 which oppose any opening. of the tube 25 under the pressure of the gases released by the cooking.

At a temperature substantially between 200 and 250 ° C and for a period of one minute to three or four minutes, the microfiche roll 30 is liquefied and then transformed, after cooling, into a hard and compact cylinder allowing no more deciphering and without no smoke. During heating, the LEDs 16 and 17 are on. After cooking, the timer 20 cuts the power to the resistor 7 but keeps the light 17 on for ten minutes, time necessary for the tube 25 to cool down. At the end of this period, the light 17 goes out, the horn 18 is temporarily activated.

The user unscrews the cap 9, the tube 25 is lifted by the spring 8 and can be grasped easily, at a temperature where any risk of burns is eliminated.

The tube 25 is then discarded with its cap 26 to avoid the release of foul smells, the fumes being however condensed inside the tube after cooling thereof.

The device according to the invention is of small volume, can be easily placed on a desk and its production is economical, the price of the tube 25 being moreover negligible.

Experience also shows that maintaining the tube 25 in the vertical position is relatively critical to ensure good destruction of the microfiches.

It goes without saying that the invention is not limited to the embodiment described and that it is possible to provide alternative embodiments. In particular, to accelerate the cooling, or can remove the layer 5 of insulation by retaining only the wall 4 and install in the body 13 a cooling blower controlled by the timer 20. Such an embodiment is shown in Figure 4. The outer casing 41 houses a turbine 42 which directs a flow of air sucked through the opening 43 towards the heating element 7a which is here devoid of insulation to accelerate cooling under the effect of the blower. The entire housing is held by columns 44.

Another industrial embodiment using a fan and comprising a control circuit slightly different from that of the first embodiment is shown in FIGS. 5 and 6. In this version, the heating jacket 101 is fixed between an upper flange 102 pierced with holes and a base constituted by a low-profile aluminum cup 113, provided with a return spring 108, this fixing being ensured by means of three spacing columns 103. The flange 102 is fixed on the hollow body 104 of molded material of the 'apparatus by screws 105, the posts 103 being themselves screwed into a steel ring 109 which is thus subject to the flange 102. The connection of the posts 103 with the cup 113 is ensured by screws 131.

The heating jacket 101 comprises a cylindrical wall 106 around which a shielded resistor 107 is wound helically. The jacket 101 is surrounded by a cylindrical aluminum reflector 119 intended to avoid excessive heating of the neighboring parts.

As before, the envelope 101 is intended to receive the disposable tube 25 containing the microfiches and closed by its cap 26, which has a frustoconical bearing having for example a slope of 3%.

The ring 109 is tapped at 109a to re cevoir a threaded metal cap 110 intended to be screwed by means of an attached flywheel 111, of insulating material, thermally insulated from the cap 110 but which is made integral by screws 112. In service, under the cap 110 is disposed a counterweight 132 on which the cap 110 can press via an anti-friction ball 133. The counterweight 132 is intended to press the plug 26 of the tube 25 under the pressure communicated by the cap 110 when the latter is screwed in the ring 109 thanks to the handwheel 111.

Under the cup 113 is arranged a propeller fan 124 fixed on the removable bottom of the body 104. The air circulation is ensured by suction openings 104a and outlet 104b. (Arrows F).

The electrical supply circuit of the resistor 107, shown diagrammatically by the conductors 151, serves two safety contactors 117a, 117b mounted in series, fixed on plates 116a, 116b carrying printed circuits and respectively intended to control the correct positioning from the bottom of the tube 25 in the cup 113 and the correct closure of the cap 110.

To this end, the contactors 117a, 1 17b are controlled by feelers 141a, 141b passing respectively through the cover 113 and the ring 109. These feelers 141a, 1416 ensure that when they are pushed back the contactors 117a, 117b are closed by means of levers 118a, 118b articulated on the pads 116a, 1166.

The contactors 117a, 117b are also mounted in series with a thermostat 114 fixed on the cup 103 and which measures the temperature of the latter.

The conductors 151 and the conductors 152 supplying the fan 124 lead to a printed control circuit constituting a sequential system, carried by a plate 120 (FIG. 6) on which is mounted a push-button switch 123 supplied by a cord 122, an indicator 121 and a potentiometer 130 belonging to an electronic timer and making it possible to adjust the operating time of the fan 124.

• -assure l'allumage du voyant 121 pèndant le temps d'un cycle complet de fonctionnement;
• - permet l'alimentation de la résistance 107 pendant une durée variable dépendant de la température atteinte par la coupelle 113, cette durée étant fonction du nombre de microfiches à détruire contenues dans le tube 25;
• - garde en mémoire l'ouverture du thermostat 114;
• -à la coupure du thermostat 114 déclenche le ventilateur 124 pendant le temps programmé par le potentiomètre 130;
• - assure les sécurités suivantes:
• - empêcher le démarrage de la chauffe si le tube 25 n'est pas dans l'appareil (contacteur 1 17a ouvert) et/ou si la coiffe 110 n'est pas vissée (contacteur 1 17b ouvert);
• - coupe d'alimentation de la résistance 107 si la coiffe, 110 est retirée pendant la chauffe.

The circuit thus established:

• -ensures the lighting of the light 121 during the time of a complete operating cycle;
• - allows the supply of the resistor 107 for a variable duration depending on the temperature reached by the cup 113, this duration being a function of the number of microfiches to be destroyed contained in the tube 25;
• - keeps in memory the opening of thermostat 114;
• when the thermostat 114 is cut off, the fan 124 starts for the time programmed by the potentiometer 130;
• - provides the following security features:
• - prevent the start of heating if the tube 25 is not in the device (contactor 1 17a open) and / or if the cover 110 is not screwed (contactor 1 17b open);
• - cut of supply of the resistor 107 if the cover, 110 is removed during the heating.

The implementation of the device by the user is similar to that previously described.

Claims (10)

1. Apparatus for the destruction of microfiches comprising a vertical tubular jacket fixed on a base plate and surrounded by a heating resistor, characterized in that at the interior of the tubular jacket (1, 101) is housed removably a tube (25) fitted with a plug (26) made of a material which resists to temperatures of the order of 200 to 250°C, this tube presenting an interior diameter adapted to receive one or several microfiches rolled up around each other along the axis of the tube and in that the apparatus comprises means to ensure a substantially leaktight closure of the tube (25) by its plug (26) during the baking of the microfiches.

2. Apparatus as defined in claim 1, characterized in that the means for ensuring leaktight closure of the tube (25) for receiving microfiches comprise a cap (9, 110) to be screwed onto the heating jacket (1, 101) and which is provided with means (132, 133) for bearing on the plug (26) of the tube (25) during the baking operation.

3. Apparatus as defined in claim 2, characterized in that the cap carries an operating member (1, 111) for screwing the said cap by hand, this member being thermally insulated from the remainder of the cap (9, 110).

4. Apparatus as defined in one of the claims 1 to 3, characterized in that the bottom of the heating jacket (1, 101) comprises a spring (8, 108) which tends to thrust towards the exterior the tube containing the microfiches.

5. Apparatus as defined in one of the claims 1 to 4, characterized in that the heating jacket is housed within a hollow body (13, 104) containing all the electrical control circuits and provided with means for preventing transmission of the heat flux of the heating jacket (1, 101) to the exterior.

6. Apparatus as defined in one of the claims 1 to 5, characterized in that it comprises a hollow body (104) which contains the heating jacket (101) at the upper portion thereof, when in the service position, and which contains a fan (124) at the lower portion thereof, circulation of air within the body (104) being carried out in a substantially axial direction by means of orifices (104a, 104b) formed in the wall of the said hollow body (104).

7. Apparatus as defined in one of the claims 1 to 6, characterized in that it comprises programming means such as an electronic timing device for carrying out the following sequence of operations:

- control of the period of heating of the heating chamber,

- control of the cooling time,

- control of an end of cycle warning device.

8. Apparatus as defined in claim 7, characterized in that the means for controlling the period of heating of the heating chamber (101) include a thermostat (114) positioned on the said chamber.

9. Apparatus as defined in claim 7 or 8, characterized in that it includes a safety system for preventing the heating operation if the tube (25) containing the microfiches has not been placed correctly within the heating chamber (1, 101) and/or if the cap (9, 110) within the said chamber has not been suitably mounted in position.

10. Apparatus as defined in claim 9, characterized in that the safety means comprise switches (117a, 117b) with feelers (141a, 141 b) associated respectively with the bottom (113) of the heating jacket and with the cap (110).

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