GB2292084A

GB2292084A - Microwave pest exterminator

Info

Publication number: GB2292084A
Application number: GB9416191A
Authority: GB
Inventors: Paul Stephen Nightingale
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-08-10
Filing date: 1994-08-10
Publication date: 1996-02-14
Also published as: GB9416191D0

Abstract

A pest exterminator which comprises a microwave source (1), a hood (2) partially surrounding the microwave source, and an opening (8) in the hood, is used to direct sufficient microwave energy at a target pest located in the region of the opening in order to exterminate the pest. The apparatus optionally has a moisture monitor (3) for measuring moisture content in the region of the target pest, and a microwave detector (6) to detect escaping microwaves. The detector is able to turn off the microwave source if stray microwaves are detected. <IMAGE>

Description

PEST EXTERMINATOR This invention relates to a device for exterminating pests, and in particular to a device which uses microwave radiation to exterminate insect pests such as dust mites, woodworm or the like in various carrier materials, for example mattresses, carpets, wooden furniture, timber, bedding, tapestries, curtains, clothing, dried flowers, furs and foodstuffs.

Previously, extermination of such pests has been achieved principally by methods of entrapment or by direct application of a substance toxic to the pest.

An example of an entrapment method is the use of fly paper, in which a strip of adhesive coated paper or material is used to entrap pests which come into contact with it. However, this method is inconvenient and unsightly. Moreover, it relies on the pests coming into contact with the fly paper, and is therefore only suitable for trapping flying pests.

Many methods are known in the art for exterminating pests by applying a substance toxic to those pests. For example, aerosol sprays are used to kill flies and the like. These sprays can cover a much wider area than fly paper, but still rely on direct contact between the poison and the pests. Aerosol sprays are also inconvenient, in that, in order to be effective, the spray must remain in the environment for a substantial length of time. This can prove harmful to pets, plants and humans in that environment.

Various methods exist for the extermination of woodworm, in which insecticides are injected into the wood to be treated. Such methods are expensive, inconvenient, and may be harmful to the infested material.

Accordingly, it is desirable to provide a method of pest extermination, in particular insect extermination, which does not rely upon the direct application of a substance poisonous to the pests, and which can be used to treat pests infesting a variety of different materials.

We have determined that microwaves can be used to exterminate pests by directing the microwaves onto the material containing the pests. Microwaves have been found to be particularly suitable because their penetrating qualities mean that they can act at depth through a variety of materials to exterminate pests located deep therein, without causing damage to the material and without leaving toxic residues.

In accordance with a first aspect of the invention, therefore, there is provided apparatus for pest extermination, comprising a microwave source, a hood partially surrounding the microwave source for directing microwave energy in a desired direction, the hood having an opening for allowing passage of microwaves to a material to be treated, and means for supplying to the microwave source sufficient power to exterminate a target pest located in the region of the said opening.

In a preferred embodiment, the apparatus has carrying means, for example a handle.

Preferably, the apparatus has a microwave detector, located so as to detect microwaves which are travelling away from the material to be treated. The apparatus may also contain a moisture monitor and/or a temperature sensor for determining when the level of treatment has been sufficient for the particular application by monitoring the moisture content or temperature in the region of the pest.

The apparatus may also include a timer for indicating or controlling the time of treatment.

In a preferred embodiment, the apparatus also includes an alarm to indicate when one or more of the above parameters reaches a preset level. The apparatus may also comprise means for turning off the microwave source when one or more of these parameters reaches a preset level.

Preferably, the apparatus has a guard, which is located so as to limit the amount of microwave energy escaping into the environment. This guard may be made from a microwave absorbing material, such as carbon-laden paper or cloth, or a microwave reflecting material.

The microwave source may be a magnetron, or a semiconductor. The microwaves produced by the microwave source have a frequency of approximately 2,450 MHz. Higher frequencies are more effective at exterminating pests but may be less satisfactory from a safety standpoint. The frequency of 2,450 MHz is therefore a practical compromise frequency, and higher frequencies may be employed if appropriate precautions are taken.

The apparatus may include a dielectric lens, formed for example from a plastics material, to focus the microwaves onto the material to be treated. The lens may also be formed from a ceramic material.

In a further embodiment, the microwaves are focused on to the material to be treated by means of a reflector, for example a parabolic reflector, which may be able to vibrate or oscillate or rotate, or any simultaneous combination thereof.

Means may be provided for altering the aperture at the hood opening, so as to alter the microwave energy density at the hood opening.

In another embodiment the apparatus has means for wetting the carrier material, and means for drying the said material.

In a second aspect of the invention there is provided a method for exterminating pests, comprising the step of directing microwaves at a material to be treated so that the microwaves exterminate the said pests.

The pests to be exterminated may be insects, and may be present in any of the various carrier materials mentioned above.

Preferably, the method comprises the step of at least partially surrounding the materials to be treated with microwave absorbing material, for example carbon-laden paper or cloth, or microwave reflecting material so as to limit the escape into the environment of microwaves.

The moisture monitor may be used to measure the moisture content before the treatment commences, thereby determining the treatment time required to exterminate the pest. The microwaves are then directed at the material to be treated for this predetermined time, at which point the microwave source is turned off.

The method may also comprise the step of wetting the carrier material in the region of the target pest, directing microwaves at the said material so as to exterminate the said pest, and then drying the said material.

The apparatus may also include means for irradiating pests with ultraviolet light.

A number of preferred embodiments of the present invention will now be illustrated, with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram showing a pest exterminator in accordance with the present invention.

Figure 2 is a schematic diagram showing an embodiment of the pest exterminator of Figure 1, incorporating a dielectric lens formed from a plastics material.

Figure 3 is a schematic diagram showing a further embodiment of a pest exterminator in accordance with the present invention, incorporating a vibrating or oscillating parabolic reflector.

Figure 4 is a schematic diagram showing an embodiment of the pest exterminator of Figure 3, incorporating a rotating mirror and a horn.

Figure 5 is a schematic diagram showing an embodiment of the pest exterminator of Figure 1, incorporating a hood extension, a temperature sensor, and a moisture spray.

Referring first to Figure 1, the pest exterminator has a magnetron (1) contained within a hood (2) which is formed of a microwave reflecting material. The pest exterminator has a handle (9) attached to hood (2). Hood (2) is shaped so as to form a resonant cavity for the microwaves produced by magnetron (1). Hood (2) has an opening (8) to provide an exit for the microwaves. The pest exterminator has a moisture monitor (3) and microwave detectors (6) located on hood (2) in the vicinity of opening (8). A timer (4) is provided which is connected to magnetron (1). An upper guard (5) is formed of carbon-laden cloth or paper, and is located around the periphery of opening (8) so as to absorb any stray microwaves which might otherwise escape into the environment.A lower guard (10) formed of carbon-laden cloth or paper is placed underneath mattress (7), mattress (7) being the item to be treated. Lower guard (10) serves to absorb any microwaves which might otherwise pass through mattress (7) and thereby enter the environment.

As an alternative to magnetron (1), the microwave source may be a semi-conductor.

In another embodiment, the pest exterminator incorporates a temperature sensor (17), for sensing the temperature of the item to be treated in the region of the pest (see Figure 5).

The pest exterminator may also incorporate an alarm, which can be programmed to indicate when one or more of the parameters measured by the pest exterminator (that is, moisture content, radiation level, time or temperature) reach certain preset levels.

In a further embodiment, the pest exterminator has an auto shut-off device, which can be programmed to turn off magnetron (1) when one or more of the above parameters reaches a preset level.

Figure 2 shows a pest exterminator similar to the one shown in Figure 1 incorporating a dielectric lens (15) formed from polyethylene (or, alternatively, a ceramic material). Lens (15) enables microwaves produced by magnetron (1) to be focused on to mattress (7) so as to exterminate the pests contained therein more effectively.

Lens (15) produces a uniform distribution of microwave energy density over hood opening (8). Preferably, the energy density falls off to a small value at the periphery of the hood, thereby limiting the amount of microwave energy escaping into the environment.

A dielectric waveguide or a fresnel lens can also be used to similarly focus the microwaves onto mattress (7).

Figure 3 shows an embodiment of the invention which has a parabolic reflector (20) for directing microwaves produced by magnetron (1) onto mattress (7), so as to exterminate the pests contained therein more effectively.

Reflector (20) is able to vibrate or oscillate, thereby enabling the pest exterminator to produce an even spread of microwaves. Typical microwave paths (21) are also shown in Figure 3. Upper guard (5) extends under hood (2) at the periphery of opening (8), so as to block more effectively the passage of microwaves which might otherwise escape into the environment.

In an alternative embodiment, reflector (20) may be flat or spherical in shape.

Figure 4 shows an embodiment of the invention which has a flat mirror (30) mounted on a rotating cam (31).

This arrangement enables microwaves produced by magnetron (1) to be directed evenly onto mattress (7). Magnetron (1) has a horn (32) which broadens the beam of microwaves produced by magnetron (1).

Figure 5 shows an embodiment of the invention which has a hood extension (11) which can be added to hood (2) in order to provide a hood opening with a larger aperture. A moisture spray (16) is incorporated into hood (2), and is located so that it can spray moisture onto the part of mattress (7) covered by hood (2). Hood (2) also has a temperature sensor (17) to measure the temperature of mattress (7) in the region of target pest.

The pest exterminator may also include a dryer, for example a heater and/or extractor fan, to dry mattress (7) once the pests have been exterminated.

In a further embodiment, the moisture spray may be replaced by a humidifier to fill hood (2) with water vapour, and thereby increase the moisture contents of mattress (7) in the region of the target pest. Hood (2) may have an extractor, to extract the water vapour once the pests have been exterminated.

In operation, lower guard (10) formed of carbon-laden cloth or paper is placed underneath mattress (7), so that microwaves passing through mattress (7) are absorbed by guard (10). In this way, microwaves do not escape into the environment.

The pest exterminator is then placed on mattress (7) and upper guard (5) formed of carbon-laden cloth or paper is placed around the pest exterminator, so as to lie around the periphery of opening (8) of hood (2). Upper guard (5) therefore acts to absorb any microwaves which might otherwise pass into the environment.

One or both of upper guard (5) and lower guard (10) may be made of a microwave reflective material, so as to reflect microwaves which strike them back into mattress (7).

Magnetron (1) is switched on, together with timer (4), moisture monitor (3) and microwave detectors (6). The microwaves produced by magnetron (1) are directed through opening (8) of hood (2). the microwave reflective material of hood (2) serving to channel the microwaves through opening (8). The microwaves then pass into mattress (7), where they begin to exterminate the pests. Microwave detectors (6) continuously detect any microwaves which escape around the periphery of opening (8) by, for example, being reflected off the springs contained in mattress (7) and not being absorbed or reflected by upper guard (5).

Moisture monitor (3) continuously monitors the moisture content of mattress (7) which is being irradiated with microwaves, and thereby provides an indication of the likelihood of extermination of pests in mattress (7).

Trial and error will allow the operator to determine how long it takes for the moisture content of mattress (7) to fall below a level indicative of pest extermination. Once this is determined, timer (4) can be programmed to automatically switch off magnetron (1) after this time.

The pest exterminator can then be moved to a different location on mattress (7) by means of handle (9), and the described process is repeated until all of mattress (7) has been sufficiently irradiated with microwaves so as to exterminate the pests contained therein.

The pest exterminator may be adapted so that magnetron (1) is automatically switched off as soon as microwave detectors (6) detect dangerous levels of microwaves.

Magnetron (1) can also be switched off when the moisture content of mattress (7), as detected by moisture monitor (3), reaches a preset level.

Temperature sensor (17) may be provided to monitor continuously the temperature of mattress (7). Magnetron (1) is thus automatically switched off when the temperature reaches certain preset levels. House dust mites, for example, die when their environment reaches a temperature of from 570 to 600C.

An alarm may also provide an aural or visual indication when the above parameters reach certain preset levels.

Lens (15) focuses the microwaves produced by magnetron in much the same way as a glass lens focuses light waves.

Lens (15) therefore focuses the microwaves into a parallel beam, so as to achieve a reasonably uniform distribution of microwaves. The microwaves then pass out of opening (8) and into mattress (7) in the same way as above.

A uniform distribution of microwaves can also be achieved by the use of parabolic reflector (2). Reflector (20) can be vibrated, so as to provide a more uniform distribution of microwaves. Thus, microwaves pass from magnetron (1) and strike reflector (20). They are then directed towards opening (8) at an angle which is dependent upon the position of reflector (20) at the time at which the microwaves strike reflector (20). The microwaves then pass out of opening (8) and into mattress (7) in the same way as above.

Mirror (30) can also be used to provide a uniform distribution of microwaves. Mirror (30) is caused to move by rotating cam (31), so as to direct microwaves uniformly in different directions depending on the position of mirror (30) at the time at which it is struck by the microwaves.

Horn (32) acts to channel microwaves produced by magnetron (1) towards mirror (30). After striking mirror (30), the microwaves pass through opening (8) and into mattress (7) in the same way as above.

It is sometimes advantageous to dampen mattress (7) before irradiating it with microwaves. This increases the moisture content of mattress (7) in the region of the target pest, thereby enabling the microwaves to exterminate the pests more efficiently. Accordingly, in one embodiment, moisture spray (16) is used to spray water onto the surface of mattress (7) in order to dampen it.

Mattress (7) is then irradiated with microwaves as before.

Temperature sensor (17) can be used to determine when the target pest has been exterminated.

A dryer (not shown) may be incorporated into the exterminator so that mattress (7) can be dried after the operation is complete.

The energy density of the microwaves at the point of contact with mattress (7) may be altered by attaching hood extension (11). This provides an enlarged hood, the opening of which has a wider aperture than before. The microwaves are thereby directed onto a greater area of mattress (7), and so the microwave energy density is reduced.

In an alternative embodiment, hood (2) has an iris aperture which can be adjusted to enable variable microwave energy densities at the point of contact with mattress (7).

In another embodiment, mattress (7) is overlaid with a temperature sensitive sheet, before the pest exterminator and upper guard (5) is placed thereon. The temperature sensitive sheet irreversibly changes colour when the temperature of mattress (7) beneath it increases due to microwave radiation. The temperature sensitive sheet therefore provides an indication as to whether a particular part of mattress (7) has been irradiated with microwaves.

To provide a safer working environment, the operator of the pest exterminator may wear protective clothing, including goggles, in order to protect himself against stray microwave radiation.

It will be appreciated that the pest exterminator can be used on a variety of different infested materials, for example carpets, furniture infested with woodworm, timber infested with death watch beetle, or similarly infested bedding, tapestries, curtains, clothing, dried flowers, furs or foodstuffs. In these cases, the method is adapted according to the particular circumstance. This may take the form of simply arranging the location of the guards (5,10) so as to prevent the escape into the environment of microwaves produced by magnetron (1), although it will be appreciated that it may not be necessary to use guards (5,10) in every case.

The invention has been described with reference to particular embodiments illustrated in Figures 1 to 5. It will be appreciated, however, that this does not limit the scope of the invention in any way.

Claims

1. Apparatus for pest extermination, comprising a microwave source, a hood partially surrounding the microwave source for directing microwave energy in a desired direction, the hood having an opening for allowing passage of microwaves to a material to be treated, and means for supplying to the microwave source sufficient power to exterminate a target pest located in the region of the said opening.

2. Apparatus as claimed in Claim 1, additionally comprising a handle for carrying the said apparatus.

3. Apparatus as claimed in Claim 1 or Claim 2, additionally comprising a microwave detector, located so as to detect stray microwaves which are travelling away from the material to be treated.

4. Apparatus as claimed in any one of the preceding Claims, additionally comprising a moisture monitor for measuring moisture content in the region of the target pest.

5. Apparatus as claimed in any one of the preceding Claims, additionally comprising a temperature sensor, for detecting the temperature of the material to be treated.

6. Apparatus as claimed in any one of the preceding Claims, additionally comprising a timer.

7. Apparatus as claimed in any one of Claims 3 to 6, additionally comprising an alarm to indicate when the moisture content or temperature reaches a preset level or when a preset time has elapsed.

8. Apparatus as claimed in any one of Claims 3 to 7, additionally comprising means for turning off the microwave source when the moisture content or temperature reaches a preset level or when a preset time has elapsed.

9. Apparatus as claimed in any one of the preceding Claims, additionally comprising a guard, which guard is located so as to limit the amount of microwave energy escaping into the environment.

10. Apparatus as claimed in any one of the preceding Claims wherein the said microwave source is a magnetron.

11. Apparatus as claimed in any one of Claims 1 to 9, wherein the said microwave source is a semi-conductor.

12. Apparatus as claimed in any one of the preceding Claims, wherein the microwaves produced by the said microwave source have a frequency of approximately 2,450 MHz.

13. Apparatus as claimed in any one of the preceding Claims, additionally comprising a dielectric lens to focus the microwaves onto the material to be treated.

14. Apparatus as claimed in Claim 13, wherein the dielectric lens is formed from a ceramic material or a plastics material.

15. Apparatus as claimed in any one of the preceding Claims, additionally comprising a reflector to direct the microwaves onto the material to be treated.

16. Apparatus as claimed in Claim 15, wherein the reflector is a parabolic reflector.

17. Apparatus as claimed in Claim 15 or Claim 16, including means for causing the reflector to vibrate or oscillate or means for causing the reflector to rotate.

18. Apparatus as claimed in any one of the preceding claims, additionally comprising means for altering the aperture of the opening of the hood, so as to alter the energy density of the microwaves at the hood opening.

19. Apparatus as claimed in any one of the preceding claims, additionally comprising means for wetting the carrier material in the region of the target pest, and means for drying the said material.

20. The use of apparatus as claimed in any one of the preceding Claims for the extermination of pests.

21. A method for exterminating pests, comprising the step of directing microwaves at a material to be treated so that the microwaves exterminate the said pests.

22. A method as claimed in Claim 21, wherein the pests are insects.

23. A method as claimed in Claim 21 or Claim 22, comprising the step of at least partially surrounding the material to be treated with microwave absorbing or reflecting material, so as to limit the escape into the environment of microwaves.

24. A method as claimed in any one of Claims 21 to 23, wherein the material to be treated is a mattress, a carpet, an item of wooden furniture, timber, an item of bedding, a tapestry, a curtain, an item of clothing, a dried flower, a fur, or a foodstuff.

25. A method as claimed in any one of claims 21 to 24, additionally comprising the step of measuring the moisture content of the carrier material inthe region of the target pest and using the results to determine the length of time for which microwaves need to be directed at the said material in order to exterminate the said pest.

26. A method as claimed in Claims 21 to 25, additionally comprising the step of placing a temperature sensitive sheet between the pest exterminator and the material to be treated, such that the said sheet indicates when the said material has been treated.

27. A method as claimed in any one of claims 21 to 26, additionally comprising the step of wetting the carrier material in the region of the target pest, directing microwaves at the said material so as to exterminate the said pest, and then drying the said material.