METHOD AND DEVICE FOR CONTROL OF MITE IN BEDS

Abstract: A method and an apparatus for controlling bed mites. Dry air is blown through the lying surfaces of a bed so as to dry the surfaces to an extent at which mite survival conditions no longer exist. The apparatus includes means (1-4, G1, G2) for ensuring that the bed lying surface will be dried preferably while the bed is not used as a bed.

Description: METHOD AND DEVICE FOR CONTROL OF MITE IN BEDS The present invention relates to a method of controlling house dust mites in beds in accordance with the preamble of the independent method Claim, and bed mite controlling apparatus according to the preamble of the independent apparatus Claim. House dust mites thrive in the dwellings of warm-blooded animals. The mites live on epithelium, from human beings, among others. The mites therefore thrive and propagate best in bedding and in mattresses. The excretion from house dust mites is highly allergenic This allergen is one of the most common of the allergens, parallel with pollen and animal epithelium , to which human beings are subjected. The allergy frequency is directly associated with the amount of mites in the environment. Recent reports have shown that the occurrence of mites in dwellings in Sweden is increasing. It is estimated that in Sweden alone, there are about 100,000 people suffering from mite allergy and that about two million people in Sweden live in an environment in which mite allergy is likely to develop. The only commercially available agents against mite allergy are semi-permeable protective covers for mattresses blankets, pillows bedspreads etc which encapsulate the mite allergen in the bed of the person concerned. These protective covers, however, are expensive (from about SEK 1,500.00 and higher for each standard bed) and have the drawback of rustling. In order to achieve the best effect, it is recommended that the bed is left unmade in the morning, that mattress and bedding are aired in the open during the day, that sheets are preferably washed each week, and that blankets are washed each month. Although these protective measures afford a certain through-passage of air, they do not prevent mites and their excretion from passing through the guard. Thus, mites remain living in mattresses, pillows and blankets, etc and are able to propagate freely. The known protective measures do therefore not remove the antigenic substances. Accordingly, the object of the invention is to provide a method and an apparatus for controlling bed mites and therewith the production of antigenic substances. This object is achieved by the inventive method defined in the independent method Claim. The object is also achieved by the inventive apparatus defined in the independent apparatus Claim. Further embodiments of the invention are defined in the accompanying dependent Claims. The invention is based on the realization that the growth of mites can be effectively prevented at humidities beneath about 7 g water per kilo air, which corresponds approximately to a 50% relative humidity at +21°C. The increasing occurrence of mites in Swedish dwellings finds its explanation in the fact that humidity in Swedish buildings/dwellings has increased as a result of less effective ventilation, among other things. Astig ata mites {house dust mites, storeroom mites, itch- mites) have no lungs and breathe through their skin. The mites are unable to drink and therefore obtain liquid through their skin and also through solid food. The mites therefore depend on a high humidity. Mites, which are microscopic arachnids ι have a life span of about twenty-one days. Mites thrive best in temperatures in the range of +25°C to +30°C, and at a relative humidity of 65-80%. However, the growth of mites is inhibited effectively at humidities beneath 7 g per kilo (50% relative humidity at +21°C) A lowly active person (at sleep or at rest) discharges about 40 g water per hour, this water discharge constituting an important bed moisture source. According to the invention, it is important, above all else, to remove bed moisture deriving from the moisture discharged by said person, for instance, during the time in which the bed is used. The occurrence of mites in beds/bedding is reduced or eliminated by removing the primary survival conditions for mites, i.e. the moisture. This is achieved in accordance with the invention by passing through the lying surface of the bed/the mattress an air flow that has a moisture content of less than 7 g/kg, so as to take up moisture therefrom. The injection of air through the bed/mattress can be terminated when the humidity of the exhaust air from said bed/mattress is beneath 7 g/kg air. Naturally, the moisture content of the lying surface can be measured directly with known methods, so as to obtain an indication that the air blown through the bed/mattress has removed the mite life supporting conditions. The air is conveniently blown in a direction normal to the lying surface of the mattress or pillow, for instance from without and inwards or from within and outwards. According to the invention, the bed, or bedstead, may be fitted with an individual air blower for blowing air through the lying surface of the bed. This blower may conveniently be provided with an air filter. The blower may also serve several beds. If the air to be blown through the lying surface of the bed has an excessively high moisture content, the moisture content of the air will preferably be lowered before the air is blown through the mattress or pillows. This reduction in moisture content can be achieved in a conventional manner, by heating the supply air and/or by demoisturizing the supply air. It will, however, be obvious that a bed need not necessarily be provided with its own fan, since air can be caused to pass through the lying surface of the mattress/bed by connecting the mattress or pillows to a source of subpressure (a central vacuum cleaner) , or to a compressed air outlet (often provided in hospital wards) . According to one embodiment of the invention at present preferred, blowing of air through the lying surface is controlled by a timer, so that the air will be blown through the lying surface during those times at which the bed is not used for sleeping purposes. This ensures that the person using the bed will not be disturbed by draughts, fan noise, etc., associated with mite control. This control of the air blown through said lying surface may also include a sensor which detects bed moisture content and activates the blower solely when the need arises. Alternatively, there may be provided sensor means that detect the moisture level of the exhaust air and which cuts-off the air supply when the moisture content of the exhaust air falls beneath a predetermined value. The bed/mattress are permeable to air over the whole of their effective lying surface, and for this reason the outer bed covering comprises a generally air-permeable material so as to allow air to pass therethrough. In this regard, the mattress may include an air distributing system, for instance an air distributing chamber or a distributing chamber system, so as to provide uniform distribution of through-passing air across the lying surface. In the case of interior sprung mattresses, the spring accommodating space can be used as an air distributing chamber. In the case of plastic foam mattresses or foamed rubber mattresses, the uppermost layer of the mattress may be formed from foam that has open air-permeable cells, wherein an air distributing system, for instance a perforated hose, may be laid in a loop between the uppermost mattress layer and the mattress layer immediately therebeneath. It is known to pump air through spring mattresses and plastic foam mattresses, and also through an armchair with the intention of improving lying comfort/sitting comfort as a result of air blown through the user-contacting surface over substantially the whole of this surface. It is also known in this regard to heat or cool the air to further enhance the comfort of the user. See for instance DE-B-1, 65 , 00, US-A- 4,825,488, US-A-3,266,06 , DE-A-1, 654,384 and DE-A-1,778, 130. However, none of these patent documents disclose that mites can be controlled by air injection or that mites can be controlled by blowing air through bedding surfaces that have come into contact with a person, such as to dry these surfaces to a moisture content at which mites are no longer able to survive. Furthermore, the known technique requires air to be blown through the mattress while the bed is occupied. The invention will now be described in more detail with reference to an exemplifying embodiment thereof and also with reference to the accompanying drawing. Fig. 1 illustrates inventive apparatus comprising a blower device and a mattress served thereby schematically and from above. Fig. 2 is a schematic section view taken on the line II-II in Fig. 1. Fig. 3 is a schematic view corresponding to Fig. 2 and illustrating an alternative embodiment of the invention. Fig. 1 shows from above a mattress 6 which has beneath its outer layer an air distribution conduit 7 having perforations 8 and being positioned to provide a generally uniform flow of air upwardly through the lying surface of the mattress. Air is supplied to the conduit 7 by means of an electric air pump 3. The supply air is first fed through an air filter 5 upstream of the pump 3. A sensor G2 is provided for sensing the humidity of the air leaving the air pump 3. G2 activates an air heater 4 when the air exiting from the pump 3 has a humidity that exceeds 7 g/kg, such that the air entering the conduit 7 will preferably have a humidity of essentially less than 7 g/kg air. The air passing through the outer layer 62 of the mattress 6 (for instance, a foamed plastic layer) shall be capable of drying the lying surface of said outer layer 62 to an extent at which mite survival conditions no longer exist. A moisture sensor GI may be arranged to sense the humidity in the outer layer 62. The sensor GI may be adapted to stop the air pump 3 and its associated devices (e.g. the heater 4) when the lying surface or outer surface of the mattress or bedding is sufficiently dry for the intended purpose. A timer 2 may be connected in the current supply circuit to the pump 3 and the heater 4, such as to activate the pump and heater during those times when the mattress 6 is not used as a bed, for instance during the day when the owner of the bed is at work. It will be understood that the invention does not necessarily require a specially constructed mattress/bed. For instance, it is fully conceivable to use an air distribution device that comprises two textile sheets 71, 72 for instance, having a size corresponding to the size of the bed sheets for instance, these textile sheets 71, 72 being joined mutually around a region that corresponds to the lying surface of the mattress/bed 6 so as to establish between the sheets 71, 72 an air distribution chamber 73 which is connected to an air supply conduit corresponding to the conduit 7 in Fig. 1. The desired air distribution and drying of said surfaces can be achieved by suitable selection of the air-permeability of the sheets 71, 72. An air distribution device may also be provided in a pillow, this device comprising, for instance, perforated conduits that are connected to an air pump (suction or pressure) similar to the embodiment shown in Figs. 1 and 2. Bed moisture is concentrated generally on the pillow and mattress, which thus need to be dried by blowing air through those surfaces thereof that come into contact with the person lying in the bed. The bed clothes, such as duvet, blankets and the like may, of course, be dried in a corresponding manner, although when the air flow is directed vertically upwards, the exhaust flow from the mattress will also act on the undersurfaces of the bed clothes and therewith dry the bed clothes to a suitable extent.

Claims: CLAIMS 1. A method of controlling bed mites, characterized by passing through a lying surface on the bed mattress a flow of air whose humidity is below 7 grams per kilo air until the moisture content of the lying surface of said mattress which corresponds to the exhaust air leaving said lying surface has a moisture content of at most 7 grams per kilo. 2. A method according to Claim 1, characterized by sensing the humidity of the supply air that shall be passed through the lying surface and, when necessary, lowering the humidity of the supply air to a level beneath 7 grams per kilo air prior to passing said air through the lying surface. 3. A method according to Claim 2, characterized by demoisturizing and/or heating the supply air such as to lower its humidity. 4. A method according to any one of Claims 1-3, characterized by passing the airflow through the mattress lying surfaces while the bed is not used as a bed. 5. A method according to any one of Claims 1-4, characterized by sensing the moisture content of the mattress lying surface or the humidity of the exhaust air leaving the mattress lying surface and stopping the injection of air through said lying surface when the sensed humidity has a value corresponding to at most 7 grams of water per kilo of air in the exhaust air. 6. A method according to any one of Claims 1-5, characterized by filtering the supply air prior to passing the air through the mattress. 7. Apparatus for controlling bed mites, characterized in that the bed/mattress lying surface is air-permeable (8, 62; 71, 72); and in that means (1-5, GI, G2, 7) are provided for passing an air flow having a humidity of at most 7 grams per kilo through the lying surface. 8. Apparatus according to Claim 7, characterized in that the apparatus includes a moisture sensor (GI) which is adapted to stop the injection of air through the lying surface when the moisture content of the lying surface no longer provides mite survival conditions, wherein the exhaust air from the lying surface has a moisture content of at most 7 grams per kilo. 9. Apparatus according to Claim 7 or 8, characterized in that the air injection means are guided by a timer which allows the air injection means to operate when the bed is not used as a bed. 10. Apparatus according to any one of Claims 7-9, characterized in that the apparatus includes sensor means (G2) for sensing the humidity of the supply air, wherein the sensor means is adapted to activate means for lowering the humidity of the supply air prior to passing the supply air into the bed/mattress, so that the air delivered to the bed lying surface will have a humidity below 7 grams per kilo air.

Inventors: FREIJ BENGT, FREIJ, BENGT
Applicants: BENGT FREIJ ARKITEKTKONTOR AB, FREIJ BENGT, FREIJ, BENGT
Application year: 1996
Main classification: A47C27
IPC codes: A47C21