Automatic thermosealer

The present invention relates to an automatic thermosealer of the type pointed out in the preamble of the independent claims.

In the medical and dental field use of sterile instruments is necessary, so as to prevent infections from being transmitted from patient to patient.

Normally a reusable instrument such as a scalpel or a cutter is used on a patient, then it is washed manually or in a thermodisinfector, rinsed, dried and sterilised. Sterilisation in a steam autoclave is considered the gold standard in this field. Since the sterilised instruments are not always used immediately after their sterilisation, normally the instruments to be sterilised are introduced into an autoclave wrapped in envelopes aiming at preserving their sterility state after extraction from the autoclave. Use of envelopes made of two coupled materials, paper and film is known, these materials offering several advantages. The film is transparent and therefore allows the user to see the envelope's contents. The paper material has pores that open due to the high temperature reached in the autoclave and therefore enable the steam to enter the envelope and perform its sterilisation function; as the temperature decreases at the end of the cycle, and the residual moisture is eliminated, the pores close again thus inhibiting the environmental air from entering and therefore maintaining the sterility state of the instrument contained therein. In addition, often the paper material contains coloured indicators enabling the operator to distinguish the envelopes already submitted to sterilisation from those that have not yet being sterilised.

Normally, each individual instrument must be put into the envelope before being sterilised in the autoclave. Presently there are on the market rolls having variable widths (50, 75, 100, 150, 200, 250, 300 millimetres, for example) and a standard length of 200 metres, from which envelopes adapted to contain the individual instruments are obtained, being then closed by two sealings at the ends.

Two documents, US 7074362 and EP 1897516 are to be considered as the important prior art.

US 7074362 discloses a thermosealer that is used with preformed envelopes. The envelope is placed on a heated surface and an arm must be lowered manually by the operator so as to close the envelope and apply two thermal sealings to an edge of the envelope; a sealing closes the instrument in a first envelope and a second sealing parallel to the first one forms a new envelope. A knife carried by the arm is used for carrying out a cut between the two sealings. The particular character of this patent resides in that the thermosealer carries out two sealings simultaneously.

The patent application EP 1897516, on the contrary, in particular discloses an adjustable roll-holder to be combined with a thermosealer similar to that described in patent US 7074362. This thermosealer however carries out a single sealing at a time.

An important part of the working time of hospital attendants/nurses/dental scrub nurses is spent in cleaning, packaging and sterilising the instruments used during the therapeutic steps. In addition, as it is well known, the repetitive movements can be the cause of skeletal muscle trouble of various seriousness in the operator.

When the operator uses a traditional thermosealer of the manual type generally he/she prepares a series of envelopes sealed on three sides; when a sufficient number of envelopes is ready, he/she is obliged to extract the roll from the sealing region and at that point he/she can carry out the second sealing on each envelope so that the instrument to be sterilised is sealingly closed inside the envelope.

Under this situation the technical task underlying the present invention is to devise a thermosealer capable of substantially obviating the mentioned drawbacks.

Accordingly, it is an aim of the present invention to provide a thermosealer of practical use, enabling the time dedicated by the medical staff to the steps of preparing/sterilising the instruments to be shortened.

It is a further aim of the present invention to prevent the operator's arm from carrying out repetitive movements and efforts. It is an additional aim of the invention to minimise the amount of coupled paper and film material used for preparing the envelopes, since these rolls are rather expensive.

Finally, due to automation of the operations, a constant and repeatable quality of the sealings can be ensured.

The technical task mentioned and the aims specified are achieved by a thermosealer as claimed in the appended independent claims.

Preferred embodiments are highlighted in the sub-claims.

The object of the present invention will be now described with the aid of the following figures representing:

• Fig. 1 the thermosealer taken as a whole;
• Fig. 2 the advancing or feeding mechanism of the coupled paper and film material;
• Fig. 3 the sealing mechanism;
• Fig. 4 the feeding and cutting mechanism of the coupled paper and film material (first sealing);
• Fig. 5 the sealing mechanism of the envelope (second sealing)
• Fig. 6 the hot-air path.

In Fig. 1 the thermosealer as a whole is denoted by reference numeral 1. It is adapted to form envelopes 13 starting from rolls 3a and 3b of coupled paper and film material (in the following referred to as "coated paper") 3 and briefly comprising: winding and unwinding means for the roll of coated paper 3 including at least one roll-holder 4, a rest surface 2 for the coated paper 3, sealing means 20 and cutting means 28 for the coated paper, quick activation means for reaching various suitable purposes and consisting of an operating push-button panel 5, a centimetre scale 6 for measurement of the instruments, a centimetre scale 7 for measurement of the amount of coated paper, a signalling LED 25.

In Fig. 1 the thermosealer is represented as loaded with two rolls 3a and 3b. In practice it is possible to work with one of the two rolls 3 at a time of coated paper represented in the figure; the roll 3b that is not used at that moment can remain on the roll-holder 4, but the coated paper has to be removed from the feeding mechanism. Alternatively, it is possible to simultaneously work with the two rolls obtaining envelopes of identical sizes in length.

The hereinafter described sequence of operations relates to use of the thermosealer with only one roll. In normal use, the operator measures an instrument 12 to be put into an envelope on the centimetre scale 6 and, through the coated-paper feeding push-button 8, causes moving forward of a length of coated paper a little longer than that of the instrument. Should the amount of coated paper be erroneously too much, the operator can cause the excess coated paper to be taken up by means of the coated-paper retraction push-button 9. Operation of the motor causes the coated paper to be moved forward and backward until the push-button 8 or 9 is maintained pressed; when the push-button is released the forward or backward movement is stopped. When the amount of coated paper is correct, the operator presses the push-button 10a that will carry out sealing and cutting simultaneously. Once these two operations have been completed, the coated paper of roll 3a is moved backward automatically by a few millimetres, so that the sealing region is free from the coated paper.

When the operator has to put many instruments of same size into the envelopes, he/she can, through suitable storage means, store the length of the coated paper section to be pulled out in the following manner: the operator keeps one of the two storage push-buttons 11 pressed for a time exceeding 3 seconds, then he/she causes the desired amount of coated paper, through the push-button 8, to be moved forward or, through the push-button 9, to be taken up; at the moment he/she activates suitable quick activation means, in particular when he/she presses the sealing and cutting push-button 10a, the envelope length is automatically stored. Afterwards, each time the operator wishes to have an envelope of that size, he/she presses the storage push-button 11. Two storage push-buttons 11 are present on the machine and they allow two different lengths of coated paper to be stored.

In a further embodiment it is also possible to produce a number of envelopes at will, all having the same sizes, in an automatic manner: the operator sets a desired number of envelopes of the preset size and the thermosealer automatically produces them until the set number has been reached.

At this point an envelope 13 sealed at the sides thereof is at the operator's disposal. The instrument 12 is inserted into the envelope 13 and execution of the second sealing parallel to the first one occurs, the open side 14 being inserted into slit 15 and suitable quick activation means being activated, in particular the push-button 10b being pressed. The second sealing takes place in the same sealing region as the first sealing, the envelope to be sealed being however inserted from the front of the machine instead of from the back. Since the roll 3a of coated paper has been moved backward automatically, this ensures that the end portion of the roll does not come into contact with the side 14 of the envelope 13 that is inserted from the front. Contact between the end portion 36 of the roll and the side 14 to be sealed could in fact cause crumples on the coated paper and therefore give rise to badly made sealings (also see Fig. 5).

Shown in Fig. 2 is the advancing or feeding mechanism for the roll of coated paper. Denoted at 16 is a pressure roller maintained tightly close to the feeding roller 18 by two supports 17 driven by two springs. The pressure roller 16 is an idler roller moved by the feeding roller 18. The feeding roller 18, in turn, is moved by a feeding reduction gear 19 controlled by an encoder. This enables the machine to detect how much coated paper is unwound and therefore, if wished, to store this amount by the storage push-button 11.

Fig. 3 shows the sealing mechanism. In particular, identified as 20 is a resistor that is lifted by two cams 21, rigidly connected to a shaft 22, powered by a reduction gear 23 for lifting the resistor. When the push-button 10a or 10b is pressed, the resistor 20 lifts up and compresses the coated paper 3 on a counter-resistor 24 made of silicone, for a predetermined time sufficient to carry out the sealing. Obviously, the resistor must have previously reached the right work temperature, which is made apparent by the steady lighting of a green LED 25 on the machine front. The two up and down end-of-stroke positions of resistor 20 are controlled by a microswitch.

Shown in Fig. 4 is the cutting mechanism. Cutting of the coated paper takes place simultaneously with the first sealing, and is carried out by a blade assembly 26. The blade assembly 26 is fastened to a runner 31 sliding transversely inside a guide 27. The blade assembly 26 consists of a blade 28, a presser 29 for the coated paper, a blade support 30 and runner 31. The blade assembly 26 is rigidly fastened to a toothed belt 32 supported by two toothed pulleys (driving pulley 33a and belt-tightening pulley 33b) enabling movement by means of a cutting reduction gear 34. The blade assembly 26 slides transversely from one end to the other, controlled by two microswitches 35 at the end-of-stroke positions. In addition, the cutting speed is automatically managed by an acceleration and deceleration ramp facilitating operation thereof; the ramp is managed by an electronic card.

Presser 29 for the coated paper is such shaped that it pushes the coated paper downwards thus obtaining a guillotine effect ensuring accomplishment of a precise cut.

In Fig. 5, at the end of the first sealing and cutting operations by means of push-button 10a, the end portion 36 of the roll is at position A. When cutting has been completed, the roll 3a is automatically retracted by a few millimetres and therefore the edge 36 moves to position B, so that carrying out of the second sealing is facilitated and roll 3a is not required to be slipped off, being retained between the pressure roller 16 and feeding roller 18. Due to the foregoing, when it is necessary to prepare a new envelope, roll 3a does not need to be manually introduced again into the roll-feeding mechanism.

When the operator carries out the second sealing of the open side 14 of the envelope 13, he/she must manually insert envelope 13 into the slit 15, being sure that the sealing region is free from the end 36 of the roll.

A further advantage, resulting from the backward movement of the coated paper after the cut, resides in the fact that the coated paper is moved away from the resistor, in particular from the region where heat is very high. Being the coated paper pressed between the feeding roller and pressure roller, it is prevented from swelling or crumpling, due to heat. As a result, during the following forward movement, passage of the coated paper through the slit between the resistor and counter-resistor takes place without jamming.

Finally, represented in Fig. 6 is the air circulation inside the machine. This circulation is spontaneous because the air is not moved by a fan. Obviously resistor 20, reaching the operating temperature of 200°C, generates heat that must be dispersed. Thus, two rubber feet 38 have been provided which maintain the thermosealer 1 bottom raised from the support surface, and in the lower shell a series of slits 37 is provided to enable air from the external environment to enter (white arrows). After entering, the air acquires heat through the region of resistor 20, and comes out of the upper slit 39 and rear slits 40, so that heat generated by resistor 20 is ejected (black arrows).

In a further embodiment not shown, movable and/or removable paper guides for rolls 3a and 3b are provided; they are placed on the roll-holder 4 or in the vicinity of the rear slit for entry of the coated paper, on the thermosealer 1 body.