TECHNICAL FIELD

The present invention relates to manufacturing of a filter bag containing a premeasured batch of vegetable substances for preparation of a brewed beverage, especially for preparation of coffee.

BACKGROUND ART

It is known to prepare brewed beverages from vegetable substances which have been previously dried or roasted and ground.

The ground substances, mainly aromatic substances, essential oils, and, sometimes, tonic, exciting or tranquillising substances are brewed, for some time, in a liquid, to which they pass their active principles, and, afterwards, they are separated from the said liquid by decantation or filtration.

The beverage brewing can be hot or cold, depending on the temperature in which the process is carried out.

Cold beverages are usually brewed for days or even months and almost always in ethyl alcohol, while hot beverages are prepared in few minutes and almost always with drinkable water.

Different methods and apparatuses have been used for the preparation of brewed beverages, according to the substance and the quantity of beverage as well as the time necessary for the

preparation.

For instance, the beverage known and appreciated nearly all over the world as aromatic and moderately exciting drink obtained by roasting and grinding of coffee berries, is prepared in many different methods and with various results.

The best known are: Turkish, Italian and American coffee. The Turkish coffee is prepared by putting some ground coffee inside a vessel, pouring therein a sufficient quantity of boiling water and leaving the whole for some minutes.

Afterwards, the ready beverage can be poured into a cup and drunk as soon as the greater number of coffee powder has settled on the bottom of the cup.

The Italian coffee is usually prepared by putting a proper cjuantity of ground coffee in a metal container that acts also as a filter, and then, by slow passing therethrough water heated in an adjacent boiler (Neapolitan coffee) or a mixture of water and pressurised water steam (espresso coffee) .

The American coffee is drunk mainly in central-northern Europe and in Anglo-Saxon countries. It is prepared by making very hot water flow, slowly and continuously, through ground coffee contained in a filter bag made of porous paper of suitable type.

Machines currently used for the house preparation of American coffee usually consist of: a reservoir for feeding cold water; a properly shaped metallic pipe, connected at one end with the bottom of the feeding reservoir and having the other end free, open and turned downward; a removable collecting container having its mouth positioned under the free end of the pipe, so as to collect the

beverage; a tapered basket, having its narrower end flattened and open at the bottom, and in touching relation with the collecting container mouth, covering it. The larger end of the basket is fully open and positioned just beneath the free end of the metallic pipe.

The pipe includes a first section that is vertical, a second section that is horizontal and finally, a third section that is also vertical and extends downwards. The lower part of the first vertical section is surrounded by a spiral electric heater.

To prepare coffee by means of such machine, a filter made of water permeable paper material, having roughly the shape of the basket, is introduced in the basket, then a suitable charge of ground coffee is poured in the filter and the electric heater is operated.

Water coming from the fixed reservoir flows through the metallic pipe and is heated and partially vaporised in the section surrounded by the heater.

Then, because of the thrust exerted by the steam, the heated water goes up through the vertical section of the pipe and goes out through the open end thus dropping on the coffee.

The dropped water is retained by the filter and touches the coffee for a time long enough to obtain the brewed beverage, and then reaches the bottom of the filter and falls into the collecting container.

While being used, the filter takes a tapered shape similar to the shape of the basket. The narrow end of the filter, that is closed, is located t the bottom while the larger end is fully open.

The filter is usually obtained from a sheet

material that is overfolded and sealed along the side edges.

When it is packed, the filter takes a flat trapezoidal shape and to be used it must opened, separating the upper edges from each other.

Using this kind of filters brings about several problems, mainly due to the necessity of manual handling filters and ground coffee separately each time. First of all, opening the filter and manually measuring the batch of coffee require some time, and furthermore, part of the ground- coffee may remain in the space between the filter and the basket possibly falling into the collecting container. Lastly, usually coffee is bought already ground, or it is ground in an amount for several charges.

In both cases, the ground coffee remains for long time exposed to air and environment moisture, thus undergoing transformation that changes the characteristics of the coffee and gives an unpleasant taste to the brewed beverage.

DISCLOSURE OF THE INVENTION

The object of the present invention is to resolve the above mentioned problems, by proposing a filter containing a premeasured batch of ground coffee, that allows for a practical and efficient preparation of American coffee.

The above mentioned object is achieved by a dDisposable filter bag for preparation of a hot brewed beverage, particularly American coffee, that includes at least two superimposed sheets of water permeable material having form of a truncated circular sector, the said sheets being joined to

each other along a lower straight edge, a right side and a left side, as well as along an upper weak heat seam line forming the upper side of a-closed chamber adapted to be filled, before sealing, with a premeasured batch of a vegetable substance properly prepared.

The filter bag can be manually opened by pulling upper strips, namely a front strip and a rear strip, made in the same filter bag, and to be inserted into a basket, the said upper strips front and rear being delimited by the upper heat seam line and an upper arched edge of the said filter.

BRIEF DESCRIPTION OF THE DRAWINGS

How the foregoing object and advantages are obtained will be clear from the following description referring to the accompanying drawings in which:

- Figure 1 shows a schematic view of a disposable filter bag according to a preferred embodiment of the present invention, in overfolded condition and just withdrawn from the containing cover, together with this cover;

- Figure 2 shows the disposable filter bag of Figure 1, once it has been unfolded but still flattened;

- Figure 3 shows the disposable filter bag of Figure 1, just before being opened in the basket; - Figure 4 shows the disposable filter bag of Figure 1, fully opened inside the basket;

- Figure 5 shows another preferred embodiment of the disposable filter bag according to the present invention.

BEST MODES OF CARRYING OUT THE INVENTION

With reference to Figures 1 and 2, a first preferred embodiment of a disposable filter bag for American coffee is described.

Numeral 1 indicates a water permeable paper material filter bag, formed by two superimposed sheets of the said material, having form of a truncated circular sector delimited by a lower horizontal edge 10 and straight side edges, respectively right 11 and left: 12, and by an upper arched edge 13.

In correspondence with the side edges right 11 and left 12, the filter 1 has strong heat seam lines that permanently join the two sheets of paper along the side edges 11 and 12.

A nearly rectangular chamber 20 is delimited by the lower edge 10, two vertical weak heat seam lines, respectively right 14 and left 15, symmetrical with respect to the said lower end 10, and by a horizontal weak seam straight line 16, situated close to the upper edge 13.

The two vertical weak heat seam lines 14 and 15 also delimit, at both sides of the chamber 20, two wings, respectively a right wing 2 and a left wing 3, which can be folded inwards over the chamber 20.

The upper side 16 of the chamber 20 and the upper edge 13 of the filter delimit two upper strips, respectively a front strip 5 and a rear strip 6, each belonging to a respective sheet of paper material forming the filter 1.

The chamber 20 is filled with a proper batch of roasted and ground coffee 50 and the filter bag 1 is introduced, with the wings 2, 3 folded, into a cover 4.

When using the disposable filter bag 1, the steps E, in which the filter bag is removed from the cover, D, in which it is unfolded, and A, in which it is positioned and opened, are to be performed. The above mentioned steps will be described in the following with reference to Figures from 1 to 4.

Just before the step E, the filter 1 is housed in the cover 4, and can be removed therefrom through an opening made in the cover 4, e.g. along an upper edge 4a.

In the subsequent step D, the right wing 2 and left wing 3 are rotated about the axes defined by the respective right side 14 and left side 15 of the chamber 20, until the wings 2, 3 become coplanar with the chamber 20 and the filter bag is flat.

In the following step A, the filter 1 is introduced into a tapered basket 7, so that the strips 5, 6 extends beyond the upper rim 7a of the basket 7.

Then the strips 5, 6 are manually separated from each other, so that the weak heat seam lines, defining the upper side 16, left side 15 and right side 14 of the chamber 20, are peeled off, allowing the two sheets of the filter l to open and the same filter to assume the tapered basket shape.

The ground coffee 50, due to gravity force, settles on the bottom of the filter 1.

In a second preferred embodiment of the disposable filter bag 1, shown in Figure 5, a filter 101 includes a chamber 120 to be filled with the proper quantity of ground coffee 50.

The said chamber 120 is delimited by lower edge 110, side right side 111 and side left side 112 of the filter 101, and by a weak heat seam straight line 116 parallel to the lower edge 110 and situated

near the upper arched edge 113 of the said filter 101.

The weak heat seam line 116 - and the upper edge 113 define a pair of strips, front strip 105 and rear strip 106.

Also in this case, similarly ^' to the embodiment previously described, the filter 1 is used in the folloing way.

In a first step E the filter is removed from the cover, then in the step D it is positioned inside the basket and unfolded by manual separating the front strip 105 and rear strip 106, in the step A, thus peeling off the weak heat seam line 116, and settling of the ground coffee 50 on the bottom of the filter 101.

The above described disposable filter bag is simple and practical in use, since all the preparation operations are limited to opening and positioning the filter 1, therefore also possible waste of ground coffee 50 that fall outside the filter is avoided.

The sealed cover 4 is opened only immediately before use, assuring coffee freshness and fragrance. In the first preferred embodiment of the invention, the wings 2, 3 can be folded inwards, that allows to reduce the size of the cover 4, with remarkable advantages for transport and/or storing, and with packaging material saving.