Humidity within a Mattress Technical Field

The invention relates to an apparatus and method for controlling a level of humidity within a mattress. In particular, the invention relates to an apparatus and method for providing humidity controlled fluid to a mattress in order to control infestation of dust mites, bed bugs and/or other parasites.

Background

The term "dust mite" is used throughout this document. However, it will be understood that the invention also relates to other types of infesting parasite, such as bed bugs. The skilled person will therefore appreciate that the term "dust mite" encompasses other bed infesting parasites or bugs.

Dust mites measure about 0.25 mm in length. Dust mites feed off of pet and human dander (dead skin cells), and their waste is a major cause of allergies and asthma. People often have more pronounced asthma symptoms at night, when they are laying in a bed infested with dust mites. Dust mites inhabit warm, humid areas filled with dust, which are conditions often found in mattresses and bedding including pillows, sheets, blankets and duvets.

The house dust mite survives in all climates, even at high altitude. House dust mites thrive in an indoor environment, particularly in bedrooms and kitchens. Dust mites survive well in mattresses, carpets, furniture and bedding, with figures around 188 mites per gram of dust. Even in dry climates, house dust mites survive and reproduce easily in bedding (especially in pillows), extracting moisture from the humidity generated by human breathing, perspiration, and saliva. The average life cycle for a male house dust mite is in the order of 10 to 19 days. A mated female house dust mite can live up to 70 days, laying 60 to 100 eggs in the last 5 weeks of her life. In a 10 week life span, a house dust mite will produce approximately 2000 fecal particles and an even larger number of partially digested enzyme-covered dust particles, which may cause irritation, allergies and/or aggravation of asthma symptoms.

A known technique for killing dust mites in bedding is disclosed in GB 2334889. The method comprises at least partially encapsulating a bed with a fabric cover and inflating the cover by operation of a fan blower. The influx of air is arranged to be de-humidified or heated. An environment is provided within the cover in which the required temperature and/or humidity parameters are achieved for a predetermined period of time. In order to execute the above known method a bed must not be in use by an occupant. Further, a bed must be stripped of bedding in order to attach the fabric cover. In addition, enough room must be available to allow the fabric cover to inflate. The above method is also a one-off treatment of a bed and does not prevent infestation of a bed in between treatments.

Summary

In accordance with a first aspect of the invention there is provided a mattress humidity controller comprising: a fluid humidity altering means in fluid communication with a first fluid outlet configured to allow fluid to pass from the mattress humidity controller into a mattress; a fluid driving means operable to drive fluid from the fluid humidity altering means through the first fluid outlet; and a controller operable to measure a humidity level of a fluid from within a mattress and control the operation of the fluid driving means and the fluid humidity altering means in dependence on the measured humidity. The present invention aims to make the environment within the bed, mattress and/or surrounding bedding unsuitable for habitation by dust mites or any other type of bug that may infest beds and/or bedding. The controller of the mattress humidity controller may monitor a fluid, which may be air, from within a mattress. It is therefore possible for the controller to maintain the humidity of a fluid within a mattress at a given humidity level by operating the fluid humidity altering means, which may be a de-humidifying means, and/or the fluid driving means in dependence on the measured humidity.

Optionally, the fluid may be a gas. Optionally, the fluid may be air.

Optionally, the mattress humidity controller may further comprise a humidity control input configured to set a humidity threshold value, wherein the controller is configured to operate the fluid humidity altering means in dependence on the measured humidity exceeding the humidity threshold value.

By use of the humidity control input a user of the mattress humidity controller is able to control the desired level of humidity of fluid within a mattress. The mattress humidity controller is therefore able to control the humidity of the mattress per se. A user is, for example, able to amend the desired level of humidity to target infestations by certain species of bug. Additionally, a user is able to amend the desired humidity of fluid within a mattress dependent on local environmental conditions.

Optionally, the humidity threshold value may be in the range from 30% relative humidity to 70% relative humidity. Optionally, the humidity threshold value may be in the range from 40% relative humidity to 60% relative humidity. Optionally, the humidity threshold value may be in the range from 40% relative humidity to 50% relative humidity. The relative humidity may be determined at 1 atmosphere and 20 degrees Celsius. Dust mites do not drink but absorb moisture from the surrounding air. If the humidity is maintained within the ranges of the invention then dust mites may dehydrate and die. Additionally, the harsh environment may reduce the dust mites' urge to procreate so their numbers may be reduced in this way.

Optionally, the humidity control input may be configured to set a humidity operating envelope comprising an upper threshold value and a lower threshold value. In such embodiments, the controller may be configured to operate the fluid humidity altering means in dependence on the measured humidity exceeding the upper threshold value and in dependence on the measured humidity falling below the lower threshold value to maintain the relative humidity of the mattress within the humidity operating envelope.

Optionally, the humidity operating envelope may have a lower threshold value of 30% relative humidity and an upper threshold value of 70% relative humidity. Optionally, the humidity operating envelope may have a lower threshold value of 40% relative humidity and an upper threshold value of 60% relative humidity. Optionally, the humidity operating envelope may have a lower threshold value of 40% relative humidity and an upper threshold value of 50% relative humidity. The relative humidity may be determined at 1 atmosphere and 20 degrees Celsius.

Optionally, the mattress humidity controller may further comprise a heater wherein the fluid driving means is further operable to drive fluid from the heater through the first fluid outlet, and wherein the controller is further operable to measure a temperature of fluid from within a mattress and control the operation of the fluid driving means, the de-humidifying means and/or the heater in dependence on the measured temperature.

The heater may provide an additional de-humidifying effect on fluid driven by the fluid driving means into a mattress. Additionally, increasing or decreasing temperature may provide conditions in which it is difficult for dust mites or other parasites to survive and/or breed. Optionally, the mattress humidity controller may further comprise a temperature control input configured to set a temperature threshold value, and wherein the controller is configured to operate of the fluid driving means, the de-humidifying means and/or the heater in dependence on the measured temperature being less than the temperature threshold value.

By use of the temperature control input a user of the mattress humidity controller is able to control the desired level of temperature of fluid within a mattress. A user is, for example, able to set the desired temperature to target infestations by certain species of dust mite or other bug. Additionally, a user is able to set the desired temperature of fluid within a mattress dependent on local environmental conditions.

Optionally, the temperature threshold value may be in the range from 15 degrees Celsius to 30 degrees Celsius. Optionally, the temperature threshold value may range from 20 to 25 degrees Celsius.

Optionally, the temperature control input may be configured to set a temperature operating envelope comprising an upper threshold value and a lower threshold value. In such embodiments, the controller may be configured to operate the heater means in dependence on the measured temperature exceeding the upper threshold value and in dependence on the measured temperature falling below the lower threshold value to maintain the temperature of the mattress within the temperature operating envelope. In such embodiments the heater may be op-erable to heat the fluid and/or cool the fluid.

Optionally, the temperature operating envelope may have a lower threshold value of 15 degrees Celsius and an upper threshold value of 30 degrees Celsius. Optionally, the temperature operating envelope may have a lower threshold value of 20 degrees Celsius and an upper threshold value of 25 degrees Celsius.

Optionally, the mattress humidity controller may further comprise a second fluid outlet wherein the fluid driving means is operable to drive fluid from the fluid humidity altering means and/or the heater to the first fluid outlet and the second fluid outlet.

By providing a second fluid outlet, the mattress humidity controller is able to provide de-humidified fluid to two separate mattresses. Alternatively or in addition, the mattress humidity controller may provide de-humidified fluid to two distinct volumes within a single mattress through the first and second fluid outlets.

Optionally, the fluid driving means may comprise a pump.

Optionally, the mattress humidity controller may further comprise a fluid inlet for receiving fluid from within a mattress, the fluid inlet being in fluid communication with the fluid humidity altering means to provide a closed loop fluid system between the mattress humidity controller and a mattress.

By providing a closed loop fluid system, the fluid that is received from a mattress into the fluid inlet is able to be reconditioned, e.g. de-humidified and/or reheated, and supplied again to a mattress. Using a closed loop system reduces the amount of work that the de-humidifier and/or heater is required to do to return the humidity and/or temperature of the air to the desired levels. This is because the air has previously been de-humidified and/or heated and so may require less de- humidification and/or heating to return it to the desired levels than ambient air taken from the external environment. According to the invention in a second aspect there is provided a mattress comprising a mattress humidity controller as described above.

Optionally, the mattress may further comprise a first internal volume comprising a first mattress fluid inlet configured to receive fluid from the first fluid outlet of the mattress humidity controller. The first internal volume may contain open springs or pocket springs according to known mattress construction techniques. De-humidified fluid may be supplied to the first internal volume thereby allowing de-humidified fluid to pass through the elements of the mattress construction to prevent dust mite or other bug infestation.

Optionally, the first internal volume may further comprise a first mattress fluid outlet configured to provide fluid from within the mattress to the fluid inlet of the mattress humidity controller. The provision of a first mattress fluid outlet allows fluid from within the mattress to be fed into the mattress humidity controller. Fluid that has previously been within a mattress is more likely to be close to a desirable humidity level than fluid obtained from external sources. Therefore, the de-humidifier may be required to do less work to alter the humidity of fluid obtained from within a mattress, e.g. to raise or lower the humidity level of the fluid to a desired level.

Optionally, the mattress may further comprise a second internal volume may comprise a second mattress fluid inlet configured to receive fluid from the second fluid outlet of the mattress humidity controller, wherein the second internal volume comprises a plurality of second mattress fluid outlets arranged to expel air into bedding arranged on or near a surface of the mattress.

In this way fluid at differing pressures may be received at the first and second internal volumes. The plurality of second mattress fluid outlets allows pressurised jets of fluid to be expelled from the second internal volume across a surface area of the mattress. This may, for example, allow fluid to pass through bedding items arranged on a surface of a mattress.

Optionally, the second internal volume may comprise a length of tubing comprising straight portions arranged in parallel lines, wherein adjacent straight portions are connected at one end by a curved portion. Using a length of tubing arranged as described allows the plurality of second mattress fluid outlets to be distributed across a large area without the size of the second internal volume being too large. A desired pressure within the second volume is thereby maintained more easily than if the second volume was of a size large enough to cover an entire surface of a mattress.

Optionally, the length of tubing may be substantially flat and is arranged beneath an outer surface of the mattress, and wherein the plurality of second mattress fluid outlets are arranged to expel fluid through the outer surface of the mattress.

The use of a substantially flat length of tubing prevents the tubing from interfering with a subject lying on the mattress. In addition, the use of a substantially flat length of tubing allows a greater number of second mattress fluid outlets to be arranged to expel fluid in a common direction, i.e. through an outer surface of a mattress.

Optionally, the second internal volume may be manufactured from PVC.

According to the invention in a third aspect there is provided a method for controlling a humidity level of a fluid within a mattress comprising: measuring the humidity of a fluid from within the mattress; operating a fluid humidity altering means to alter the humidity of the fluid; and operating a fluid driving means operable to drive humidity altered fluid from the fluid humidity altering means into the mattress wherein the operation of the fluid humidity altering means and the fluid driving means is in dependence on the measured humidity of the fluid.

Optionally, the fluid driving means and/or the fluid humidity altering means may be operated to maintain the humidity of fluid from within the mattress at a constant humidity.

Specific Description Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

Figure la is a perspective view of a mattress humidity controller;

Figure lb is a perspective view of a mattress humidity controller;

Figure lc is a block schematic diagram of a mattress humidity controller; Figure 2 is a flow diagram showing a method of maintaining a humidity level of fluid from within a mattress;

Figure 3a is perspective view of a mattress comprising a mattress humidity controller;

Figure 3b is a sectional view along A-A through the mattress of Figure 3a;

Figure 4a is a perspective view of a mattress according an embodiment of the present invention; and

Figure 4b is a perspective view of a section of the top of the mattress of Figure 4a showing the top layer of the mattress partially cut away.

Figure 5 shows a representation of the likelihood of the occurrence of different phenomena within a mattress against relative humidity within a mattress.

The invention may generally define a mattress humidity controller that is able to monitor a fluid from within a mattress and operate to inject fluid into the mattress to raise or lower the humidity level of the fluid therein. In this way the mattress humidity controller is able to maintain the humidity level of a fluid within a mattress at a desired level. This provides the advantage that dust mite and other bug infestations are prevented. The invention may also generally define a mattress arranged to receive fluid from a mattress humidity controller. Further, the invention may also generally define a mattress comprising the mattress humidity controller. Further still the invention may also generally define a method for maintaining a humidity level of a fluid within a mattress.

In some embodiments of the invention the fluid may comprise air. Air may be preferable for use as a fluid in the invention as it is easy to obtain from the surrounding environment.

Referring to Figure la, there is shown a rear left perspective view of a mattress humidity controller 110 according to embodiments of the invention. The mattress humidity controller 110 includes a fluid humidity altering means 112. The fluid humidity altering means may be operable to raise or lower the humidity of air. The fluid humidity altering means 112 may, for example, be a de-humidifier, a re-humidifier or both. In exemplary embodiments, the fluid humidity altering means 112 may be a de- humidifier using a compressor to remove moisture from air. In further embodiments, the fluid humidity altering means 112 may be a de-humidifier using a desiccant or salt based method of removing moisture from air. In yet further embodiments, the fluid humidity altering means 112 may be a de-humidifier using Peltier coolers to remove moisture from air.

A first fluid outlet 114 is in fluid communication with the fluid humidity altering means 112 to allow air to pass from the fluid humidity altering means 112 through the first fluid outlet 14 and into a mattress (see Figure 3a).

A heater 116 is disposed in the first fluid outlet 114. The heater 116 may be operated to heat air passing through the first fluid outlet 114 as it enters a mattress. The heater 116 comprises an electrical heater element through which electrical current is passed to heat an element. In other exemplary embodiments the heater 116 may be another form of heater such as a gas powered heater or a ceramic heater.

The heater 116 is positioned at the first fluid outlet 114. This may be preferable as it minimises the amount of heat loss before the air passes through the first fluid outlet 114 and into a mattress. However, in other exemplary embodiments the heater 116 may be positioned at a different location, for example at any point between the fluid humidity altering means 112 and the first fluid outlet 114 or at any other location within the closed loop fluid system referred to below.

A fluid driving means 118 is operable to drive air from the fluid humidity altering means 112 out through the first fluid outlet 114 and into a mattress. The fluid driver 118 may for example be a pump, although in other exemplary embodiments the fluid driver may be a fan or other means for transferring fluid from one location to another.

A first pump outlet pipe 120 is connected between the pump and the fluid humidity altering means 112.

A section of ducting 122 extends from the fluid humidity altering means 112 to a fluid inlet 124. The fluid inlet 124 is in fluid communication with the fluid humidity altering means 112 and receives air from within a mattress. The length of ducting 122 is straight and extends away from the fluid humidity altering means 112 to a length sufficient to allow the first fluid outlet 114 and the fluid inlet 124 to be positioned at separate locations. Advantageously the first fluid outlet 114 and the fluid inlet 124 are positioned at opposite ends of a mattress. In alternative exemplary embodiments the length of ducting 122 may be any shape or length. In this way, the length of ducting may be configured to allow the fluid inlet 124 to be positioned to accommodate different sizes of mattress. In other alternative embodiments the length of ducting 122 may be configured to allow the fluid inlet 124 to be positioned at any location with respect to a mattress.

A second fluid outlet 126 extends from the pump 118. The second fluid outlet 126 is arranged to allow air from the fluid humidity altering means 112 to exit into a mattress. Accordingly, the pump 118 is configured to drive air from the fluid humidity altering means 112 out through the first fluid outlet 14 and the second fluid outlet 126. In the embodiment shown in Figures la and lb the heater 116 is positioned such that air driven from the pump 118 only passes the heater 116 when exiting the mattress humidity controller 110 through the first fluid outlet 114. In alternative embodiments the heater 116 may be positioned such that air driven from the pump 118 is heated by the heater 116 before it exits the mattress humidity controller 110 through both the first fluid outlet 114 and the second fluid outlet 126.

A water tank 128 is connected to the fluid humidity altering means 112. The water tank 128 may be configured to receive moisture extracted from air passing through the fluid humidity altering means 112 if the fluid humidity altering means 112 comprises a de-humidifier. The water tank 128 may be configured to provide a source of moisture if the fluid humidity altering means 112 comprises a re- humidifier.

Referring to Figure lb there is shown a rear right perspective view of a mattress humidity controller 110. Features of the mattress humidity controller 110 that are the same as the mattress humidity controller 110 shown in Figure la are given the same reference numeral.

A humidity control input 130 is positioned on the side of the ducting 122. The humidity control input 130 is configured to allow a humidity threshold value to be set by a user of the mattress humidity controller 110. The humidity control input 130 may be a knob that may be turned to a predetermined calibrated position to set the level of humidity of air corresponding to the humidity threshold value. In other exemplary embodiments the humidity input controller 130 may be a digital input means comprising a keypad and a display, wherein the keypad is operable to enter a humidity threshold value. In yet further exemplary embodiments a humidity threshold value may be predetermined and stored within a controller (shown in Figure 2) of the mattress humidity controller 110.

In embodiments the humidity threshold value may be in the range from 30% to 70% relative humidity. In other embodiments the humidity threshold value may be in the range from 40% to 60% relative humidity. In other embodiments the humidity threshold value may be in the range from 40% to 50% relative humidity.

A temperature control input 132 is positioned on the side of the ducting 122. The temperature control input 132 is configured to allow a temperature threshold value to be set by a user of the mattress humidity controller 110. The temperature control input 132 may be a knob that may be turned to a predetermined calibrated position to set the level of temperature of air corresponding to the temperature threshold value. In other exemplary embodiments the temperature input controller 132 may be a digital input means comprising a keypad and a display, wherein the keypad is operable to enter a temperature threshold value. In yet further exemplary embodiments a temperature threshold value may be predetermined and stored within a controller (shown in Figure 2) of the mattress humidity controller 110. In embodiments the temperature threshold value may be in the range from 15 to 30 degrees Celsius. In other embodiments the temperature threshold value may be oin the range from 20 to 25 degrees Celsius.

Referring to Figure lc there is shown a block schematic diagram of a mattress humidity controller 110. Features of the mattress humidity controller 110 that are the same as the mattress humidity controller 110 shown in Figures la and lb are given the same reference numeral. A fluid humidity altering means 112 is in fluid communication with a first fluid outlet 114 and a second fluid outlet 126. The fluid humidity altering means 112 is also in fluid communication with a fluid inlet 124 via ducting 122.

A pump 118 is configured to drive air from the fluid humidity altering means 112 out of the first fluid outlet 114 and out of the second fluid outlet 126.

A heater 116 is positioned at the first fluid outlet 114 to heat air leaving the first fluid outlet 114.

A controller 134 comprises a sensor 136 and a microprocessor 138. The sensor 136 is connected to the ducting 122 to allow air within the ducting 122 to be sensed by the sensor 136. In certain embodiments it is preferable to place the sensor 136 as close to the fluid inlet 124 as possible as this results in the sensed air corresponding as closely as possible to the air inside a mattress. The sensor 136 is configured to communicate sensed humidity and temperature to the microprocessor 138.

The microprocessor 138 is configured to communicate with a humidity control input 130 and a temperature control input 132 to receive a humidity threshold value and a temperature threshold value respectively. The microprocessor 138 is further configured to communicate with the fluid humidity altering means 112 to operate the fluid humidity altering means 112. The microprocessor 138 is further configured to communicate with the heater 116 to operate the heater 116. The microprocessor 138 is further configured to communicate with the pump 118 to operate the heater 118.

Referring to Figure 2 in combination with Figure lc, operation of an exemplary embodiment is described.

The air from within a mattress is measured at step 210. The air enters the fluid inlet 124 from a mattress and is indicative of the air within the mattress. The air from within the mattress is sensed by the sensor 136 to determine the humidity of the air. The humidity value of the air from within the mattress is communicated to the microprocessor 138 from the sensor 136. Also, the humidity threshold value is communicated to the microprocessor 138 from the temperature input control 130.

At step 212, the microprocessor 138 reads the humidity threshold value from the humidity control input 130, which has been set by a user.

The microprocessor compares the sensed humidity with the humidity threshold value at step 214 to see if the humidity off the air within the mattress is greater than the humidity threshold value.

If the measured humidity of the air from within the mattress is not greater than the humidity threshold value then the microprocessor communicates with the fluid humidity altering means 112 to turn it off at step 216. If the fluid humidity altering means 112 is already turned off then this step may not be necessary. The microprocessor 138 then communicates with the pump 118 to turn it off at step 218. This step also may not be necessary if the pump 118 is already turned off. The above steps starting with step 210 are repeated to measure the air from within the mattress again.

If the measured humidity of the air from within the mattress is greater than the humidity threshold value then the microprocessor 138 communicates with the fluid humidity altering means 112 to turn it on to reduce the humidity of the air at step 220. The microprocessor 138 also communicates with pump 118 to operate the pump 118 to drive air from the fluid humidity altering means 112 out of the first fluid outlet 114 at step 222. The above steps starting with step 210 are repeated to measure the air from within the mattress again. The pump 118 may also be operated to drive air from the fluid humidity altering means out of the second fluid outlet and this operation is discussed in detail below. The air that is driven out of the first fluid outlet 114 enters the mattress reducing the humidity of the air within the mattress and thereby creating conditions within the mattress that are unfavourable for the existence of dust mites and other organisms capable of infesting a bed.

In an alternative embodiment, instead of returning to step 210 the method may continue to assess the temperature of the air from within the mattress against the temperature threshold value. In a similar fashion to that described above in respect of humidity, the microprocessor 138 may read the temperature threshold value from the temperature control input 132. The microprocessor 138 may then compare the temperature threshold value to the sensed temperature of the air from within the mattress. If the measured temperature is greater than the temperature threshold value then the microprocessor may turn off the heater 116 and the pump 118. If the measured temperature of the air from within the mattress is less than the temperature threshold value then the microprocessor 138 may turn on the heater 116 and the pump 118.

The humidity and the temperature of the air within a mattress may be subsequently controlled. After both the humidity and the temperature have been controlled in this way then the method may return to step 210 to measure the humidity and temperature of the air from within the mattress.

In certain embodiments the heater may be controlled to operate when the mattress humidity controller 110 is first switched on and/or when the sensed temperature falls below 20 degrees Celsius and the humidity altering means 112 is operating.

In other alternative embodiments an additional step of turning on or off a heater 116 may be added. The heater 116 may supplement the de-humidifying capabilities of the fluid humidity altering means 112 by drying the air as it passes the heater 116. For example, if the humidity level of the air from within the mattress is greater than the humidity threshold value then after the step 220 of turning on the fluid humidity altering means 112 an additional step of turning on the heater 116 may be undertaken. Conversely, if the sensed humidity of the air from within the mattress is less than or equal to the humidity threshold value then the additional step of turning off the heater 116 may also be undertaken. Referring to Figures 3a and 3b there is shown a mattress 300 comprising a mattress humidity controller 110 as described above.

The mattress humidity controller 110 is fitted to the underside of the mattress 300. The mattress comprises a first internal volume 302. The first internal volume 302 has a first mattress fluid inlet 304 configured to receive air from the mattress humidity controller 110. The mattress humidity controller 110 is fitted to the base of the mattress 300 such that the first fluid outlet 114 of the mattress humidity controller 110 is inserted into the first mattress fluid inlet 304 of the mattress 300. The first internal volume 302 of the mattress 300 further comprises a first mattress fluid outlet 306 configured to provide fluid from within the mattress 300 to the fluid inlet 124 of the mattress humidity controller 110. Accordingly, the ducting 122 of the mattress humidity controller 110 runs down the length of the mattress 300 to align the fluid inlet 124 of the mattress humidity controller 110 with the first mattress fluid outlet. Air from within the first internal volume 302 of the mattress 300 thereby enters the ducting 122 of the mattress humidity controller 110.

The mattress may be of an open spring or a pocket spring construction. Both of these mattress constructions are known to the skilled person. Referring to Figure 4, the first internal volume 302 of the mattress 300 contains pocket springs 308. The pocket springs 308 are shown only in the left area of the first internal volume 302. However, it will be understood that the pocket springs 308 will fill the first internal volume 302 as is normal practice in mattress design. The mattress 300 further comprises a second internal volume 310. The second internal volume 310 receives air from the second fluid outlet 126 of the mattress humidity controller 110 through a second mattress fluid inlet 311. The second internal volume 310 is arranged at the top of the mattress 300 nearest to a surface of the mattress on which bedding is placed. The top surface of the mattress 300 therefore forms an outer wall of the second internal volume 310. The top surface of the mattress 300 comprises a plurality of second mattress fluid outlets 312. The plurality of second mattress fluid outlets 312 are small holes that are configured to generate high pressure jets of air from the second internal volume 310 into bedding arranged on the top surface of the mattress 300. In embodiments of the invention, the plurality of second fluid outlets 312 may have a diameter in the range from 0.3 mm to 0.7 mm. In a particular embodiment the plurality of second fluid outlets 312 may have a diameter of 0.5 mm. Further, in embodiments of the invention, the plurality of second fluid outlets 312 may be spaced apart by a distance from 15 mm to 25 mm. In a particular embodiment, the plurality of second fluid outlets 312 may be spaced apart by a distance of 20 mm.

The first internal volume 302 and the second internal volume 310 are separated from each other by internal wall 314. The first internal volume 302 and the second internal volume 310 are therefore separate from each other and air entering the first internal volume 302 cannot enter the second internal volume 310 through the internal wall 314. Accordingly the internal wall 314 may be manufactured from a material not permeable by air.

In operation air is pumped into the mattress 300 by the pump 118 of the mattress humidity controller 110. Air is pumped through first fluid outlet 114 of the mattress humidity controller 110 and the first mattress fluid inlet 304 and into the first internal volume 302. The air passes through the first internal volume 302 to control the humidity of air within the mattress 300. Air is able to pass through the first internal volume 302 as the construction of the mattress 300 within the first internal volume 302, e.g. the open or pocket spring design, is entirely permeable by air. The outer walls of the first internal volume 302 are permeable to air . However, only a limited amount of air is able to exit the mattress 300 through the outer walls of the first internal volme 302 because the material of the oputer walls of the first internal volume provide resistance to the passage of air. The majority of air is therefore forced through the first internal volume 302 and out of the first mattress fluid outlet 306 and back into the mattress humidity controller 110 by air pressure generated by the pump 118. In this way, the mattress 300 and the mattress humidity controller 110 form a closed loop. That is conditioned air is pumped from the mattress humidity controller 110 into the mattress 330, where it passes through the first internal volume 302 and out of the first mattress fluid outlet 306 back into the mattress humidity controller 110 before being conditioned and sent back to the mattress 300. In this way additional moisture from, for example, perspiration of a user lying on the mattress 300 may be quickly removed.

Air that is conditioned to maintain a desired humidity of the air within the mattress 300 may be fed into the first internal volume 302 to control dust mite infestation.

As explained above, the process of pumping air into the first internal volume 302 is controlled by the microprocessor 138 (shown in Figure lc) based on at least a humidity threshold value that may be set by a user. The microprocessor 138 controls whether air that is de-humidified or re-humidified is pumped into the first internal volume 302 to maintain the air within the first internal volume 302 at the humidity threshold value.

Air is also pumped through the second fluid outlet 126 through the second mattress fluid inlet 311 and into the second internal volume 302. In some embodiments of the invention the walls of the second internal volume 310 are not permeable by air and so air pressure within the second internal volume 310 is increased by air being pumped into the second internal volume 310 from the mattress humidity controller 110. In other embodiments of the invention the walls of the second internal volume 310 are permeable by air. In such embodiments the pump 118 is configured to input air into the second internal volume 310 at a rate greater than the rate at which air escapes through the walls of the second internal volume 310, thereby increasing the air pressure within the second internal volume 310. The pump 118, the plurality second mattress fluid outlets 312 and the size of the second internal volume 310 are configured to generate a pressure within the second internal volume 310 sufficient to drive air out of the plurality of second fluid outlets 312. Air is forced out of the plurality second mattress fluid outlets 312 under pressure in jets of air. The jets of air are able to permeate bedding arranged on the top surface of the mattress 300 to prevent infestations of dust mites and other infesting parasites within the bedding. The supply of air to the second internal volume 310 may also be controlled by the microprocessor 138. The microprocessor 138 may control the air pumped into the second internal volume 310 on a timer basis. For example, after a user has woken and left a bed, the user may initiate a process of pumping air into the second internal volume 310, e.g. by pressing a button on the outside of the mattress humidity controller 110. After initiation of the process of pumping air into the second internal volume 310, the microprocessor may activate the humidity altering means 112 and the pump 118 to pump air of a predetermined humidity into the second internal volume 310 of the mattress 300. The level of humidity required may be set, for example, to be the same as the humidity threshold value discussed above. The microprocessor may then control the humidity altering means 112 and the pump 118 to pump conditioned air into the second internal volume 310 for a predetermined length of time. The predetermined length of time may be calculated to prevent infestation of dust mites within the bedding. In certain embodiments of the invention, the pump 118 may be operated after a user of the mattress 300 has awoken and/or left a bed in which the mattress 300 is installed. The pump 118 may be configured to run for a fixed period of time. The fixed period of time may be from 30 minutes to 3 hours. In particular embodiments, the fixed period of time may be 1 hour or 2 hours. Alternatively, the pump 118 may be configured to operate continuously. Referring to Figures 4a and 4b, a mattress 400 is shown in which the second internal volume comprises a length of tubing 402. The length of tubing 402 may be arranged between an outer covering 404 of the mattress 400 and a foam layer 406 of the mattress 400. The length of tubing 402 may be substantially flat so as not to interfere with the comfort of a user lying on the mattress 400. As such the height of the length of tubing 402 should be minimised. In certain embodiments, the length of tubing 402 may be a pipe having an internal diameter in the range 3 mm to 7 mm. In a particular embodiment, the length of tubing may be a pipe having an internal diameter of 5 mm.

The length of tubing 402 comprises a plurality of straight portions arranged in parallel lines. Each pair of the plurality of straight portions are connected at one end by a curved portion. This provides a serpentine, wave-like or zig-zag shaped pathway. The length of tubing therefore 402 comprises an enclosed second internal volume. An upper surface of the length of tubing 402 comprises a plurality of second mattress fluid outlets 408 arranged to expel jets of air as explained above. In this embodiment the outer surface of the mattress 400 is permeable to air and so the jets of air expelled from the length of tubing 402 are able to penetrate through the surface of the mattress 400 and into bedding arranged on the surface of the mattress 400.

The length of tubing 402 may be manufactured from polyvinyl chloride (PVC). PVC is a pliable material that will absorb any pressure exerted on it by the weight of a user lying on the mattress 400 therefore not causing any discomfort. Further, PVC is not permeable by air and therefore allows air pressure within the length of tubing 402 to build up under pressure exerted by the pump 118.

Referring to figure 5, there is shown a plot of the likelihood of a range of phenomena occurring within a mattress against relative humidity within the mattress. The triangular portions shown in each row of the plot represent the likelihood of the phenomena of that row occurring. Taking "Bacteria" as an example, the best conditions for Bacteria occur at 0% relative humidity and conditions become less favourable for Bacteria as the relative humidity increases. Above 30% relative humidity the conditions for Bacteria are bad enough that the likelihood of occurrence of Bacteria is minimal. Similarly, dust mites only occur at a relative humidity of 50% or more. The shaded area between 40% and 60% relative hiumidity covering all rows represents an exemplary humidity operating envelope.

In embodiments of the invention the fluid humidity altering means is able to operate as a de-humidifier. If the measured relative humidity of air exiting a mattress exceeds a humidity threshold value then the de-humidifier is turned on to reduce the humidity of the air within the mattress.

In other embodiments of the invention, the fluid humidity altering means may operate as a de-humidifier and a re-humidifier. In such embodiments the humidity operating envelope has an upper threshold and a lower threshold. If the measured relative humidity of air exiting a mattress falls below the lower threshold value then the fluid humidity altering means operates as a re-humidifier and if the measured relative humidity of air exiting a mattress exceeds the upper threshold value then the fluid humidity altering means operates as a de-humidifier. The relative humidity of a fluid within the mattress is thereby maintained within the humidity operating envelope.

The skilled person will envisage further embodiments within the scope of the appended claims.