Background Art Cigarettes, which are the cylindrical rolls of finely cut tobacco, generate a variety of toxic oxides, such as nicotine and tar, while smoking the cigarettes. When such toxic oxides are repeatedly sucked into the lungs, they are deposited in said lungs and may cause a variety of serious diseases, such as pulmonary tuberculosis or lung cancer. On the other hand, when said toxic oxides are absorbed into the blood through the mucous membrane of the mouth, nose, bronchus, or stomach, they exceedingly promote the secretion of adrenaline in the blood, thus contracting the muscles of the blood veins and causing a

variety of vein diseases.

Since tobacco addicts the smokers to nicotine, it is very difficult for smokers to quit smoking cigarettes. Therefore, most cigarette manufacturers have actively studied in order to minimize the amount of toxic oxides of their cigarettes and/or to improve the filter structure of their cigarettes so as to effectively filter the smoke from the cigarettes and thereby to minimize the amount of toxic oxides absorbed by the human organs.

The filters of the cigarettes are designed to filter the toxic oxides, such as nicotine and tar, while smoking the cigarettes. Conventional filters of the cigarettes are typically classified into several types as follows: That is, the conventional filters of the cigarettes are classified according to the structure of the filters into a single filter consisting of one integrated filter segment, a double filter formed by a linear arrangement of two filter segments, and a multiplex filter formed by the linear arrangement of a plurality of different kinds of filter segments. The filters are also classified according to the material of the filters into a fiber filter, a chemical granule-laden filter, and a carbon granule-laden filter. In the prior art, fiber filters, particularly laden with carbon or chemical granules, have been most preferably and widely used as the filters of the cigarettes.

In a conventional fiber filter for cigarettes, the fibroid material of the filter is oriented along the axis of the filter so as to be parallel to the flow current of the sucked smoke while smoking the cigarette. Since the fibroid material of the fiber filter is parallel to the flow current of the sucked smoke while smoking the cigarette, the smoke is hydrodynamically concentrated to the portion around the central axis of the filter. Therefore, the smoke suction force while smoking a cigarette most strongly acts along the central axis of the cylindrical fiber filter, thus forcing the toxic oxides, such as nicotine and tar, to be concentratively filtered and deposited in the portion around said central axis of the filter. When the nicotine and tar are concentratively filtered and deposited in the portion around the central axis of the filter while smoking a cigarette as described above, the filter is reduced in its filtering function and cannot accomplish its designed filtering function.

In an effort to overcome such problems experienced in the conventional filters of cigarettes, a great number of micro- perforations 1 may be regularly formed around the cover paper of the filter at a predetermined middle portion so as to form an annular arrangement of perforations 1. The above micro- perforations 1 allow atmospheric air to be sucked under pressure into the filter through them when a smoker sucks the smoke while smoking a cigarette. The outside part of the

filter is thus allowed to more actively perform its filtering function. This somewhat reduces the concentration of smoke to the portion around the central axis of the filter, and forces the smoke to be diffused to the entire sectional area of the filter when the smoke is sucked into the mouth of the smoker.

Therefore, the conventional filter with such micro- perforations 1 somewhat improves its smoke filtering effect.

However, the conventional filters with such micro- perforations 1 are problematic in that the amount of atmospheric air sucked into the filter through the perforations 1 is very limited, and so it is almost impossible to completely prevent the concentration of the smoke laden with nicotine and tar to the portion around the central axis of the filter while smoking a cigarette Disclosure of the Invention Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a smoke diffusing device for cigarette filters, which is provided with a plurality of regularly arranged perforations and is set in the middle portion of a cylindrical cigarette filter so as to uniformly diffuse the smoke to the entire sectional area of the filter while smoking a cigarette, thus allowing the filter to more effectively filter the smoke to remove harmful or toxic oxides, such as nicotine and tar, from the smoke through adhesion or absorption.

Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a perspective view of a conventional cigarette filter; Fig. 2 is a perspective view of a smoke diffusing device for cigarette filters in accordance with the primary embodiment of the present invention; Fig. 3 is a perspective view of a smoke diffusing device for cigarette filters in accordance with the second embodiment of the present invention; and Fig. 4 is a sectional view of a cigarette filter provided with a smoke diffusing device of the present invention.

* Description of the Reference Numerals in the Drawings * 1 : micro-perforations 2,2' : smoke diffusing device 3 : body 4 : perforations 5 : boss 6 : tobacco 7 : inside filter segment

8 : outside filter segment Best Mode for Carrying Out the Invention The smoke diffusing device 2 of this invention is set in a cylindrical cigarette filter. This diffusing device 2 has a thin disc-shaped body, with the same diameter as that of the filter and a plurality of perforations formed on the body.

Each of the perforations, formed on the disc-shaped diffusing device, has a conical profile, of which the diameter varies such that said diameter is gradually enlarged in a direction from the smoke inlet to the smoke outlet. These conical perforations allow the smoke to slightly expand in volume while passing through the perforations prior to being diffused under pressure into the outside filter segment of the filter.

In the present invention, it is preferable to set the thickness of the smoke diffusing device 2 to mm.

When the thickness of the device 2 is less than 0.5 mm, it is almost impossible to form any desired difference in the diameter between the smoke inlet and the smoke outlet of the perforations. That is, when the device 2 is thinner than 0.5 mm, it is almost impossible to form the desired conical profile of each perforation or to accomplish the desired smoke volume expanding effect and the smoke diffusing effect. On the other hand, when the thickness of the device 2 is larger

than 4.0 mm, the smoke passage formed by each perforation is exceedingly long such that the perforations may be undesirably blocked by nicotine and tar. Therefore, it is more preferable to set the thickness of the diffusing device to 1.0-2.0 mm.

In addition, the total number of perforations, formed on the central portion and the peripheral portion of the device 2, is preferably set to five or more so as to allow the device 2 to have a desired smoke diffusing effect. When the total number of the perforations is thirty or more, the smoke may be hydrodynamically concentrated to the portion around the central axis of the filter. In such a case, the smoke diffusing device 2 of this invention cannot accomplish its desired smoke diffusing effect. Therefore, in order to allow the smoke diffusing device 2 of this invention to uniformly diffuse the smoke to the entire sectional area of the cylindrical filter and allow the filter to effectively filter the toxic oxides of the smoke through adhesion or absorption, it is more preferable to set the number of perforations between 5 and 30.

In addition, the diffusing device 2 of this invention is preferably used in a double or multiplex cigarette filter consisting of two or more linearly arranged filter segments.

When the diffusing device 2 of this invention is used in a double filter, it is preferable to set the device 2 in the filter at a position between the two filter segments. When

the smoke diffusing device 2 is used in a multiplex filter consisting of three filter segments, it is preferable to set two devices 2 in the filter at two positions between the three filter segments.

When the diffusing device 2 of this invention is set in a cigarette filter at a position between two filter segments, it is preferable to maintain a smoke chamber between the device 2 and the inside filter segment of the filter. In the present invention, the formation of such a smoke chamber may be accomplished by a boss 5 formed on the inside surface of the diffusing device 2. In such a case, it is proper to set the diameter of the boss 5 to 2/3 or less than the diameter of the main body of the device 2 and to set the thickness of the boss 5 equal to or less than the thickness of the main body of the device 2.

The construction and operational effect of the smoke diffusing device will be described in more detail with reference to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.

Fig. 2 is a perspective view of a smoke diffusing device for cigarette filters in accordance with the primary embodiment of the present invention. As shown in the drawing, the main body 3 of the smoke diffusing device 2 according to the primary embodiment of this invention is set in a

cylindrical cigarette filter, and so the body 3 has a thin disc-shaped body, with the same diameter as that of the filter. In the present invention, it is preferable to set the thickness of the said disc-shaped body 3 of the device to 0.5 -4.0 mm. When the thickness of the body 3 is less than 0.5 mm, it is almost impossible to form a desired difference in the diameter between the smoke inlet and the smoke outlet of the perforations as described above, and so the device 2 fails to accomplish the desired smoke volume expanding effect and the smoke diffusing effect. On the other hand, when the thickness of the body 3 is larger than 4.0 mm, the smoke passage formed by each perforation is exceedingly long such that the perforations may be undesirably blocked by nicotine and tar. It is thus more preferable to set the thickness of the disc-shaped body 3 of the diffusing device to 1.0-2.0 mm.

The perforations 4 are formed on the body 3 of the diffusing device 2, and allow the smoke to uniformly pass through them prior to being diffused under pressure into the outside filter segment 8 when a person sucks the smoke of the cigarette. In the present invention, the total number of perforations 4 is preferably set between 5 and 30. When the disc-shaped body 3 of the device 2 has too few perforations 4, it is difficult for the smoke to pass through the body 3 of the device 2. In such a case, a person cannot smoothly suck

the smoke while smoking a cigarette. On the other hand, when the disc-shaped body 3 of the device 2 has too many perforations 4, the smoke is hydrodynamically concentrated to the portion around the central axis of the filter. In such a case, the smoke diffusing device 2 cannot accomplish its desired smoke filtering effect.

Each of the perforations 4 of the disc-shaped diffusing device 2 has a conical profile, of which the diameter varies such that said diameter is gradually enlarged in a direction from the smoke inlet to the smoke outlet. These conical perforations 4 thus allow the smoke to expand while passing through the perforations 4, and more effectively diffuse the smoke to the entire sectional area of the filter. In the present invention, it is preferable to set the diameter of the smoke inlet of each perforation 4 to mm and the diameter of the smoke outlet of each perforation 4 to be larger than that of the smoke inlet by mm. When the diameter of the smoke inlet of each perforation 4 is smaller than 0.1 mm, it is very difficult for the smoke to smoothly pass through the perforations 4. On the other hand, when the diameter of the smoke inlet of each perforation 4 is larger than 1.0 mm, the perforations 4 reduce the smoke diffusing effect of the device 2. Therefore, it is preferable to carefully set the diameter of the smoke inlet and the smoke outlet of each perforation 4 in consideration of both the

number of the perforations 4 and the thickness of the body 3 of the device 2.

In the present invention, each of the perforations 4 may be freely designed to have a variety of cross-sections, such as a circular cross-section or a polygonal cross-section, for example, a triangular cross-section, or a rectangular cross- section. When each of the perforations 4 is designed to have a polygonal cross-section, the smoke flow is hydrodynamically increased in its flow rate at the corners of the cross-section and the smoke diffusing effect of the device 2 is enhanced.

Therefore, it is more preferable to design each of the perforations 4 of this invention to have a polygonal cross- section.

Fig. 3 is a perspective view of a smoke diffusing device for cigarette filters in accordance with the second embodiment of the present invention. In the present invention, it is preferable to form a smoke chamber between the smoke diffusing device 2'and the inside filter segment of the filter when the diffusing device is set in the cigarette filter at a position between the two filter segments of a double or multiplex filter. Such a smoke chamber preferably prevents the perforations 4 from being unexpectedly blocked by impurities removed from the inside filter segment, and temporarily collects the smoke therein so as to allow the smoke to more smoothly pass through the perforations 4. In the embodiment

of Fig. 3, the formation of such a smoke chamber is accomplished by a boss 5 formed on the central portion of the inside surface of the disc-shaped body 3. Of course, it is preferable to form a perforation 4 on the boss 5 of the body 3 for allowing the portion around the central axis of the filter to perform a smoke filtering function.

Fig. 4 is a sectional view of a cigarette filter provided with a smoke diffusing device 2'having such a boss 5 at its central portion.

When a person sucks the smoke while smoking a cigarette, the smoke from the tobacco 6 primarily passes through the inside filter segment 7, and so the inside filter segment 7 primarily filters the smoke to remove the toxic oxides, such as nicotine and tar. The primarily filtered smoke is, thereafter, temporarily collected in the smoke chamber defined within the filter by the boss 5 of the device 2'. The smoke from the smoke chamber passes through the perforations 4 while slightly expanding in volume, and is uniformly diffused under pressure into the entire sectional area of the outside filter segment 8. That is, the smoke from the tobacco 6 primarily and secondarily passes through the inside and outside filter segments while being uniformly and effectively diffused by the device 2'. Therefore, the toxic oxides, such as nicotine and tar, are uniformly filtered by and deposited into the entire sectional area of the outside filter segment 8. It is thus

possible for the smoke diffusing device 2'of this invention to prevent the smoke from being hydrodynamically concentrated to a portion around the central axis of the filter.

Therefore, the smoke diffusing device of this invention remarkably reduces the amount of toxic oxides, such as nicotine and tar, remaining in the smoke finally sucked into the mouth and the lungs of a person.

In the present invention, one or two smoke diffusing devices 2 of the present invention may be set within one cigarette filter as desired. In addition, it is possible to adjust the number of perforations 4 formed on a diffusing device 2 as desired. Furthermore, it should be understood that the material of the device 2 may be selected from a variety of light materials, such as plastic or aluminum, without affecting the functioning of this invention.

IndustrialApplicability As described above, the present invention provides a smoke diffusing device for cigarette filters. The smoke diffusing device of this invention is set in a cigarette filter, and uniformly diffuses the smoke to the entire sectional area of the filter while preventing an undesired concentration of the smoke to the portion around the central axis of the filter. This device thus allows the filter to

more effectively filter the smoke to remove harmful or toxic oxides, such as nicotine and tar, from the smoke through adhesion or absorption. Therefore, the smoke diffusing device of this invention allows the cigarette filter to effectively remove the toxic oxides from the smoke while retaining the taste of cigarettes.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.