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Title:
HAIR DRYING DEVICE WITH THREE-DIMENSIONAL FILTER
Document Type and Number:
WIPO Patent Application WO/2001/087108
Kind Code:
A1
Abstract:
A description is given of a hairdrying appliance (1) provided with a shell (2) in which is mounted a rotor (3) that draws air in from the outside through a filter (4) positioned upstream of the rotor, and the said filter (4) consists of a sheet (5) of porous material covering at least some of the spaces (8e) present on the outer surfaces of a three-dimensional support frame (6) having an axis (N-N) aligned approximately with the axis (V-V) of the said rotor (3), in which the said sheet (5) is made of synthetic-resin fibres, and means (7) are provided that enable the degree of occlusion of its pores to be assessed visually.

Inventors:
SORESINA FLAVIO (CH)
Application Number:
PCT/IB2001/000756
Publication Date:
November 22, 2001
Filing Date:
May 03, 2001
Export Citation:
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Assignee:
LIGO ELECTRIC S A (CH)
SORESINA FLAVIO (CH)
International Classes:
A45D20/12; (IPC1-7): A45D20/12
Foreign References:
US5810911A1998-09-22
US5490336A1996-02-13
US3891417A1975-06-24
DE4143237A11993-07-01
Attorney, Agent or Firm:
Fiammenghi-domenighetti, Delfina (Fiammenghi-Fiammenghi Via San Gottardo 15 Lugano, CH)
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Claims:
Claims
1. Hairdrying appliance (1) provided with a shell (2) in which is mounted a rotor (3) that draws air in from the outside through a filter (4) positioned upstream of the rotor, the appliance being characterized in that the said filter (4) consists of a sheet (5) of porous material covering at least some of the spaces (8e) present on the outer surfaces of a threedimensional support frame (6) having an axis (NN) aligned approximately with the axis (VV) of the said rotor (3).
2. Hairdrying appliance according to Claim 1, characterized in that it is provided with means (7t) that enable the degree of occlusion of the pores of the said sheet (5) of porous material to be assessed visually.
3. Hairdrying appliance according to Claim 2, in which the said means for assessing the state of occlusion of the said sheet (5) of porous material are one or more transparent windows (7t) formed in the lateral surface of a cavity (7) in which the filter (4) is housed.
4. Hairdrying appliance according to Claim 3, in which the said transparent windows (7t) contain dark lines etched or drawn onto them that can be distinguished by contrast only until the degree of occlusion of the pores of the said sheet (5) of porous material reaches a predetermined value.
5. Hairdrying appliance according to Claim 3, in which the said sheet (5) of the porous material carries dark lines capable of being distinguished by contrast only until the degree of occlusion of the pores of the said sheet (5) reaches a predetermined value.
6. Hairdrying appliance according to Claim 3, in which there are at least two of the said transparent windows (7t), and they are arranged on the lateral surface of the said cavity (7) on opposite sides relative to the axis (NN) of the filter (4) in such a way that a beam of light L passing transversely through both of them also passes through the filter (4) itself.
7. Hairdrying appliance according to one of the previous claims, in which the said support frame (6) is in the form of a solid having a lateral surface (61) situated around its said axis (NN) and two faces (6f, 6g) arranged transversely to the latter, the said sheet of synthetic resin (5) being mounted on the support frame (6) in such a way as to cover the spaces (8e) of its abovementioned lateral surface (61) and at least the space or spaces (8e) of that face (6g) of its said faces (6f, 6g) which is more external relative to the said hairdrying appliance (1), and the nett total surface area of all the spaces (8e) is at least three times the area of the cross section of the abovementioned cavity (7).
8. Hairdrying appliance according to one of the previous claims, in which the said cavity (7), formed in its shell (2) upstream of the said rotor (3), and which contains the said filter (4), is so shaped that the air drawn in by the rotor (3) can reach and pass through all the said spaces (8e) covered by the syntheticresin sheet (5), and its walls contain a plurality of through slots (9n).
9. Hairdrying appliance according to one of the previous claims, in which the said sheet of porous material (5) consists of a layer of highporosity polypropylene fibres coupled to a polyamide backing sheet.
10. Hairdrying appliance according to Claim 6, in which the said support frame (6) is made of plastic.
11. Hairdrying appliance according to either of Claims 8 and 9, in which the said sheet of porous material (5) is attached to the outside or inside of the said support frame (6) by adhesive bonding. AMENDED CLAIMS [received by the International Bureau on 10 September 2001 (10. 09.01); original claims 111 replaced by amended claims 110 (3 pages)] 1. Hairdrying appliance (1) provided with a shell (2) in which is mounted a rotor (3) that draws air in from the outside through a filter (4) positioned upstream of the rotor, the said filter (4) consisting of a sheet (5) of porous material covering at least some of the spaces (8e) present on the outer surfaces of a threedimensional support frame (6) having an axis (NN) aligned approximately with the axis (VV) of the said rotor (3), characterized in that the said support frame (6) is in the form of a solid having a lateral surface (61) situated around its said axis (NN) and two faces (6f, 6g) arranged transversely to the latter, and the said sheet of synthetic resin (5) is mounted on the support frame (6) in such a way as to cover the spaces (8e) of its abovementioned lateral surface (61) and at least the space or spaces (8e) of that face (6g) of its said faces (6f, 6g) which is more external relative to the said hairdrying appliance (1), the nett total surface area of all the spaces (8e) being at least three times the area of the cross section of the abovementioned cavity (7).
12. 2 Hairdrying appliance according to Claim 1, characterized in that it is provided with means (7t) that enable the degree of occlusion of the pores of the said sheet (5) of porous material to be assessed visually.
13. 3 Hairdrying appliance according to Claim 2, in which the said means for assessing the state of occlusion of the said sheet (5) of porous material are one or more transparent windows (7t) formed in the lateral surface of a cavity (7) in which the filter (4) is housed.
14. Hairdrying appliance according to Claim 3, in which the said transparent windows (7t) contain dark lines etched or drawn onto them that can be distinguished by contrast only until the degree of occlusion of the pores of the said sheet (5) of porous material reaches a predetermined value.
15. Hairdrying appliance according to Claim 3, in which the said sheet (5) of the porous material carries dark lines capable of being distinguished by contrast only until the degree of occlusion of the pores of the said sheet (5) reaches a predetermined value.
16. Hairdrying appliance according to Claim 3, in which there are at least two of the said transparent windows (7t), and they are arranged on the lateral surface of the said cavity (7) on opposite sides relative to the axis (NN) of the filter (4) in such a way that a beam of light L passing transversely through both of them also passes through the filter (4) itself.
17. Hairdrying appliance according to one of the previous claims, in which the said cavity (7), formed in its shell (2) upstream of the said rotor (3), and which contains the said filter (4), is so shaped that the air drawn in by the rotor (3) can reach and pass through all the said spaces (8e) covered by the syntheticresin sheet (5), and its walls contain a plurality of through slots (9n).
18. Hairdrying appliance according to one of the previous claims, in which the said sheet of porous material (5) consists of a layer of highporosity polypropylene fibres coupled to a polyamide backing sheet.
19. Hairdrying appliance according to one of the previous claims, in which the said support frame (6) is made of plastic.
20. Hairdrying appliance according to one of the previous claims, in which the said sheet of porous material (5) is attached to the outside or inside of the said support frame (6) by adhesive bonding.
Description:
HAIR DRESSING DEVICE WITH THREE-DIMENSIONAL FILTER The present invention relates to the technological field of the production of hairdrying appliances.

As is known, such appliances consist essentially of an appropriately shaped shell containing in its interior a rotor which, when driven by an electric motor, draws air in from the outside and blows it out, heated or otherwise, towards the hair to be dried.

In ordinary hairdryers it often happens that hairs or other foreign bodies, drawn into the shell by the depression generated by the said rotor, become twisted around the spindle of the rotor and/or the air-heating resistors, stopping the rotor and damaging the electric motor and/or burning on contact with the said resistors and giving off an unpleasant smell.

To avoid these drawbacks, some more advanced types of hairdrying appliances are provided with a disc-shaped filter placed upstream of the rotor, but in view of the weak depression created by the rotor, the filter is usually made from metallic mesh or from woven metallic wires variously twisted together, or from other materials, the aim being always to leave a plurality of holes of relatively large dimensions for the air to pass through, the holes always being much greater than can act as an effective barrier to the passage of hairs, dust, mites and so forth.

The inventor of the present invention therefore decided that, if the filter of a hairdrying appliance has a gross total surface area for the passage of air greater than the abovementioned surface area of the cross section of the fan compartment, it can be made from materials with much smaller holes, the necessary total nett area for the passage of air being arrived at by

the large number of holes which it is possible to make in a larger surface area.

He also decided that a filter of this kind can also be made out of a sheet of synthetic-resin fibres in which the mean dimensions of its pores are so small as to effectively filter out practically all the impurities from the air.

The only drawback that could arise with a filter constructed in this way is that, with the passage of time, its pores tend to become clogged and the user has no objective way of deciding when to replace the filter.

The inventor has taken this aspect into account also, and has come up with a hairdrying appliance in which the abovementioned filter has its filtering surface mounted on a three-dimensional support frame, of which it covers the lateral surfaces and also the surface of at least one of the faces disposed at right angles to the axis of the filter, which is aligned with the axis of the rotor, and the filter consists of a sheet of synthetic-resin fibres. In order that the degree of occlusion of its pores can be observed visually, the inventor has provided the hairdrying appliance of the invention with suitable means, which will be described in the course of the present description.

More specifically, the subject of the invention is a hairdrying appliance as described in the preamble of the appended Claim 1, characterized by the matter set forth in the characterizing part of the same claim.

A more detailed description will now be given of an illustrative embodiment of a hairdrying appliance according to the invention, which will show more clearly its technical characteristics besides all the advantages which it offers. In the course of this

description, which is not to be understood as either binding or limiting with respect to other embodiments possible on the basis of the teachings of the said Claim 1, reference will also be made to the appended drawings, which show: -in Figure 1, a longitudinal section through the abovementioned illustrative embodiment of a hairdrying appliance according to the invention, the section being taken on a horizontal plane perpendicular to the plane of symmetry of the said appliance; -in Figure 2, a longitudinal section of a part only of the appliance of Figure 1, the section being taken on a plane parallel to the appliance, i. e. at right angles to that used for the section of the previous figure; and -in Figure 3, an enlarged perspective view of an illustrative embodiment of a filter belonging to the appliance shown in Figures 1 and 2.

It should be pointed out that, for obvious reasons of clarity, in Figures 1 and 2 the sheet of porous material of the filter has been shown as if perfectly transparent.

Beginning with Figure 1, this shows that, in the said embodiment of a hairdrying appliance 1 according to the invention, the filter 4, visible on its own in Fig. 3, consists of a sheet of porous material 5 covering some of the spaces 8e present on the outer surfaces 61,6f, 6g of a three-dimensional support frame 6 having an axis N-N aligned approximately with the axis V-V of the rotor 3, and the total nett surface area of the said spaces 8e is at least three times the area of the cross section of the cavity 7 in which the filter 4 is housed.

More specifically, in the case considered. the support frame 6 is in the shape of a solid of rotation, more

precisely a frustum of a cone having a lateral surface 61 around its axis N-N and two faces 6f, 6g arranged transversely (at right angles in the case in question) to the said axis N-N. The said sheet of porous material 5 is mounted on the support frame 6 in such a way as to cover the spaces 8e between its structural elements, which are located on its lateral surface 61 and on that face 6g (of the said two faces 6f, 6g) which is more external relative to the hairdrying appliance 1. The other 6f of these two faces, is not covered with the sheet of porous material 5 and acts as a flow-through and collecting space for the air which filters through the other spaces 8e of the filter 4 and is then drawn in by the rotor 3.

In the example depicted, the filter 4 is housed in a cavity 7 formed in the shell 2 of the hairdrying appliance 1 and shaped in such a way as to contain it while allowing the air drawn in by the rotor 3 to reach and penetrate, with only limited pressure loss, all the spaces 8e covered with the sheet of porous material 5.

To this end, all that is required is to give the filter 4 a frustoconical shape with an open end towards the rotor 3, and make a plurality of slots 9n through the walls of the said cavity 7, leaving a gap 7j around the filter 4 through which the air can move freely before reaching and passing through all the various areas of the outer surface of the said filter 4.

The sheet of porous material 5 can be made from a layer of high-porosity polypropylene fibre coupled to a polyamide backing sheet, and can simply be glued to the outside or inside of the support frame 6, which is also made of polypropylene.

Other known methods can however be used to join together the sheet of porous material 5 and the support frame 6, which can also be made from materials other

than those mentioned above provided they have similar physical and chemical characteristics.

As mentioned, with the passage of time, because of the filtration of the air by the filter 4, the sheet of porous material 5, like all filtration elements, traps all the filtered-out impurities in its pores and this causes a decline in its efficiency accompanied by increasing losses of pressure acting on the in-drawn air flow. The filter must then be replaced. In order that the condition of the filter 4 can be assessed empirically, and a better decision made as to when to replace it, the inventor suggests providing, as shown in Figures 1 and 3, at least two transparent areas 7t on the lateral surfaces of the cavity 7 containing the filter 4, arranged on opposite sides relative to the axis N-N of the filter 4 and aligned in such a way that a straight beam of light L passing through both of them also passes through the filter 4.

The filter's efficiency can be assessed simply by looking crosswise through the cavity 7 via the said two transparent areas 7t and deducing the level of obstruction of the filter 4 by the diminution of luminosity of the said beam of light L passing through it.

Another system provided by the inventor for detecting visually the degree of occlusion of the synthetic-resin filter sheet 5 is more simply to make one or more windows 7t not necessarily arranged as described above, but simply in order that the filter 4 inside the said cavity 7 can be seen through them and its colour or external appearance be used to deduce how occluded it has become.

In order to simplify the assessment of this degree of occlusion, the inventor suggests etching or drawing on at least one window 7t or on the sheet 5 of synthetic

resin a number of lines (which may form pictures or words) that can be read by contrast against the lighter background of the said sheet 5 from the time when it is new, until the time when, because of its increasing degree of occlusion, its colour reaches a predetermined tonality that cancels out the contrast, rendering the said lines no longer distinguishable.

With a hairdrying appliance produced in accordance with the present invention, the object set by the inventor is thus achieved, namely that of providing reliable and thorough filtration of the air before it is blown onto the hair of the user, using a filter that is simple to manufacture and easy to maintain.