Patent Description:
Humidifiers are used to increase the relative humidity in an enclosed space, e.g. in a domestic or business setting. This for instance may be to compensate for humidity loss caused by ventilation or heating systems such as a central heating system, and may be desirable in order to avoid health issues such as dry skin, respiratory discomfort and the like.

A common design of such a humidifier is based on a cold evaporation principle, in which a wick or a similar material acts as a conduit between a water bath and a fan over the water bath, such that water evaporated from the wick gets propelled by the fan into the enclosed space in which the humidifier is positioned. This has the benefit that water vapour rather than larger size water droplets are expelled from the humidifier, but a drawback is that the wick can grow mould and become rather dirty over time, which is hard for a user to clean.

An alternative design of such a humidifier utilizes an ultrasonic transducer in contact with the water bath, in which the ultrasonic transducer generates small droplets and ejects these droplets into the air stream generated by the fan that spreads these droplets into ambient, where they can evaporate. This design does not significantly suffer from mould growth or other fouling, but has the disadvantage that contaminants in the water within the water bath are ejected within the water droplets into ambient, which is unhygienic. For example, <NPL>) describe the results of a study on the size distribution and concentration of particles expelled by a portable, <NUM> ultrasonic humidifier. The ultrasonic humidifier was filled with waters of varying mineral content and hardness. Aerosol size distributions were measured during <NUM> of humidifier operation in a typical bedroom. It was found that lower mineral waters produced fewer, smaller particles when compared to higher mineral waters. Chemical analyses of particles collected with a cascade impactor indicated that the minerals in emitted particles had the same relative mineral concentrations as the fill water, thus demonstrating that ultrasonic humidifiers should be considered a source of inhalation exposure to minerals dissolved in water, and that the magnitude of exposure to inhalable particles will vary with water quality. Although such exposure risks may be avoided by the use of filtered or distilled water, in practice most users tend to fill such humidifiers with tap water, thereby exposing people sharing a room with the humidifier when in operation to the mineral content in the tap water.

The applicant has proposed, but not yet published at the time of filing of this application, a solution according to which the humidifier comprises a water containing arrangement for containing water and a nebulizing device for nebulizing water from said water containing arrangement. An evaporation chamber is arranged over at least a portion of the water containing arrangement, and the evaporation chamber terminates at an impactor. A fan generates an air flow through the evaporation chamber towards the impactor. The impactor comprises an inner body having a plurality of apertures, and an outer body having a plurality of further offset apertures fluidly connected to said inner body apertures.

The design of the impactor ensures that water vapour can escape the humidifier whereas (larger) droplets are caught by the impactor and prevented from escaping the humidifier. Consequently, contamination captured in such water droplets is prevented from escaping the humidifier, thereby reducing the health risks for people exposed to the humid air released from the humidifier. This is achieved due to the fact that the apertures in the inner body of the impactor speed up the air flow generated by the fan, causing a jet effect, which air jet is then diverted owing to the fact that the further apertures are offset relative to the apertures. Due to the mass of water droplets passing through the apertures, the moment of inertia of these water droplets causes the droplets to collide with the material portions in the outer body facing such apertures, thereby capturing the water droplets and preventing them from exiting the impactor through the further apertures.

The traditional method for a mesh nebulizer uses a sponge to suck up the water, and the sponge is attached to the nebulizer bottom part and provides the water supply. When the system is using tap water, the minerals in tap water go through the sponge to the nebulizer. Some of the mineral left on the sponge can cause a calcification effect, which can reduce the water flow. Furthermore, microorganisms can also grow on the sponge which further influences the water flow and raises hygiene concerns.

The nebulizer and impactor solution as proposed by the applicant does not need a sponge for the water supply. Instead, the mesh nebulizer is at the water surface of the water supply.

In the previously proposed design, there is a water tray in fluid communication with, and topped up from, a water reservoir. The nebulizing device is positioned in said water tray.

There remain some issues with the proposed design.

First, the mesh nebulizer will be sensitive to changes in the water level. If the level is too low, there will be no water feed. If the water level is too high, the mesh nebulizer overflows and is unable to generate droplets. Although there can be a water level management structure or sensor, the water level will still have a certain tolerance. (e.g. <NUM>~<NUM>).

Second, during the humidification process, the water droplets pass through the evaporation chamber and some of the droplets will reach the ceiling of the chamber and subsequently wall down. Because the nebulizer is placed at the bottom of the chamber, the droplets can fall on top of the nebulizer. In that case, there is a risk that the droplets can block the nebulizer vibration and no droplets will be produced.

Third, over time, the device becomes dirty, as contaminants from the (tap) water and environment air collect inside the device. The mesh nebulizer has small pores, for example with <NUM> diameter, which over time can become blocked by similar size particles that get trapped in the water. Once the pores in the mesh nebulizer become blocked, the droplet production rate will become reduced accordingly. Maintenance of the device will reduce the speed in which this problem occurs, but over long time it may still occur and in addition, many users will not follow the maintenance requirement.

<CIT> provided is a floating type humidifier, and more particularly, a floating type humidifier capable of humidifying an indoor area by using an external water source while floating on water due to use of a floating unit of a hollow type so that the floating type humidifier discharges water droplets or vapour in a floating state. The floating type humidifier includes a floating body having a hollow and a water inlet hole in a lower portion through which water is introduced from the outside so that the floating body floats in a water container; an ultrasound vibrator inserted in the water inlet hole of the floating body to change the water introduced from the water container into water particles or vapor; a guide coupled to an upper end portion of the water inlet hole of the floating body to guide the water particles or the vapor generated by the ultrasound vibrator to the outside, and formed like a pipe having a guide hole in a side surface; and a discharge unit provided on the floating body under the guide hole so as to guide the water particles or the vapor from the guide to the guide hole and to discharge the water particles or the vapor to the outside.

The invention provides a humidifier comprising:.

By having the nebulizer device float on the water, the positional relationship between the nebulizer and the water is fixed so that the nebulizing function is retained reliably as the water is consumed by the device. The nebulizer device is for example a mesh nebulizer system which can float on the water surface and thus stay in contact with the water at different water heights. It also means a separate water reservoir and water tray are not needed, or a dosing or valve arrangement for topping up a water tray or any arrangement using a pump.

Thus, the floating system performs pre-filtering before the nebulization. The pre-filter for example has much (e.g. 100x) more surface area than the nebulizer element and therefore is able to filter out the particles over the lifetime of the device.

The nebulizing device may comprise an array of nebulizing elements, for example arranged in a circle. There may be between <NUM> and <NUM> nebulizing elements for example.

The, or each, nebulizing element may be situated on a surface which is angled to the horizontal to allow collected water to run away from the nebulizing element. Thus, if water droplets from the ceiling of the device fall onto the nebulizer device, they are directed to slide down so that no water blockage will influence the droplet production rate. Placing the nebulizer elements at an angle also reduces the sensitivity to changes in water level.

The surface for the, or each, nebulizing element for example comprises a drainage opening leading to the water containing arrangement. A channel may then be provided between the, or each, drainage opening and the water containing arrangement without the pre-filtering function of the pre-filter. For this purpose, the pre-filter may have pre-filter openings and larger drainage holes which couple to the drainage openings.

The evaporation chamber may terminate at an impactor and the fan is arranged to generate an air flow through said evaporation chamber towards the impactor. The impactor ensures that water vapour can escape the humidifier whereas (larger) droplets are caught by the impactor and prevented from escaping the humidifier. Consequently, contamination captured in such water droplets is prevented. Consequently, contamination captured in such water droplets is prevented from escaping the humidifier, thereby reducing the health risks for people exposed to the humid air released from the humidifier.

The impactor may comprise an inner body having a plurality of apertures, and an outer body having a plurality of further apertures fluidly connected to said apertures, wherein said further apertures are offset relative to said apertures such that each aperture in the inner body faces a section of a material of the outer body that is spatially separated from said aperture. The apertures in the inner body of the impactor speed up the air flow generated by the fan, causing a jet effect, which air jet is then diverted around the material portions of the outer body facing the apertures of the inner body owing to the fact that the further apertures are offset relative to the apertures. Due to the mass of water droplets passing through the apertures, the moment of inertia of these water droplets causes the droplets to collide with the material portions in the outer body facing such apertures, thereby capturing the water droplets and preventing them from exiting the impactor through the further apertures.

The impactor may have any suitable shape. For example, the impactor may have a cuboid or a cylindrical shape, which shape typically matches the shape of the housing of the humidifier.

The impactor may further comprise a plurality of drainage holes, each drainage hole being arranged to drain water collected by a section of the material of the outer body from the impactor. This ensures continuing functioning of the impactor, as the build-up of excessive water within the impactor due to the collection of water droplets by the material sections of the second body, which could impede the air flow from the apertures to the further apertures, is avoided.

To this end, the humidifier may further comprise at least one drainage channel extending from the impactor towards the water containing arrangement, wherein said drainage holes are aligned with said at least one drainage channel such that water trapped by the impactor can be reintroduced into the nebulizing device, e.g. via the water reservoir.

The inner body and the outer body of the impactor may extend in the same direction as said at least one drainage channel or may extend across the evaporation chamber. In other words, the impactor may be positioned in a vertical orientation, in which the further apertures are offset relative to the apertures in a vertical direction or the impactor may be positioned in a substantially horizontal orientation, in which the further apertures are offset relative to the apertures in a horizontal direction. In the latter example, the inner and outer bodies preferably are curved or angled such that water droplets captured by the impactor can flow towards the sides of the impactor in order to facilitate draining of the water droplets from the impactor through its drainage holes.

The inner body and the outer body preferably are made of or coated with a hydrophobic material to promote the drainage of collected water droplets from the impactor.

In a preferred example, the nebulizing device comprises a piezoelectrically actuated mesh structure for forming water droplets from the water in said water containing arrangement and expelling the formed water droplets into the evaporation chamber, as this allows for the formation of water droplets with a well-controlled droplet size, as the droplet size is typically governed by the size of the holes in the mesh. The mesh may be controlled by an actuator, which actuator may be configurable to adjust a vibration frequency, duty cycle and amplitude of the piezoelectric actuated mesh structure such that the rate at which water droplets are expelled by the mesh structure can be adjusted. For example, the nebulizing device may have a minimum water droplet expulsion rate of <NUM>/h, which may be increased through control of the actuator.

In an example, the piezoelectrically actuated mesh structure is arranged over a chamber having a water inlet, said chamber comprising a sponge material arranged to transport water from the water inlet to the piezoelectrically actuated mesh structure to ensure a continuous water supply to the mesh structure. The sponge material may be removable from said chamber in order to clean or replace the sponge when necessary, e.g. for hygienic reasons. The chamber may further comprise a spring that compresses the sponge against the mesh structure to further ensure a continuous water supply to the mesh structure.

Embodiments of the invention are described in more detail and by way of non-limiting examples with reference to the accompanying drawings, wherein:.

The invention provides a humidifier which comprises a water containing arrangement and a nebulizing device for nebulizing water from said water containing arrangement. An evaporation chamber is arranged over the nebulizing device. The nebulizing device is configured to float on the surface of the water in the water containing arrangement.

<FIG> schematically depicts a humidifier <NUM> proposed by the applicant. The humidifier <NUM> comprises a housing <NUM> in which a water containing arrangement including a tray <NUM> for holding water is positioned. The tray <NUM> may be the water reservoir of the humidifier <NUM>, although preferably the water containing arrangement further comprises a water reservoir <NUM>, e.g. a water tank or the like, which water reservoir <NUM> is fluidly coupled to the tray <NUM> to maintain the water level in the tray <NUM>. For example, the water reservoir <NUM> may be fluidly coupled to the tray <NUM> through a valve such as a float valve <NUM> arranged to float on the water level contained by the tray <NUM>, such that upon this water level dropping, the float valve <NUM> opens and allows water to flow from the water reservoir <NUM> to the tray <NUM>, whereas upon the water level in the tray <NUM> having increased to a certain point, the float valve <NUM> shuts and blocks the flow of water from the water reservoir <NUM> to the tray <NUM>. Other types of valves, e.g. a solenoid valve, may also be considered to fluidly couple the water reservoir <NUM> to the water tray <NUM>.

A sensor (not shown) may be positioned in the water reservoir <NUM> or the tray <NUM>, which sensor is adapted to monitor a water level in the water reservoir <NUM> or the tray <NUM> such that a controller (not shown) responsive to the sensor can cause the generation of an alert to alert a user of the humidifier <NUM> that the tray <NUM> or the water reservoir <NUM> needs replenishing. Such an alert may be generated in any suitable manner, and as the generation of such alerts is well-known per se, this will not be explained in further detail for the sake of brevity only. The water containing arrangement may be fluidly coupled to a mains water supply, e.g. through a float valve or the like to maintain a relatively constant volume of water in the water containing arrangement. Alternatively, a user may be required to manually top up the water containing arrangement.

A nebulizing device <NUM> is positioned in the tray <NUM> and is adapted to nebulize water from the tray <NUM> into water droplets that are expelled by the nebulizing device <NUM> into the evaporation chamber <NUM> that is arranged over at least a part of the tray <NUM> containing the nebulizing device <NUM>. A fan <NUM>, e.g. a centrifugal fan or axial fan, is arranged to draw air into the humidifier <NUM> through air inlets <NUM>, which may be arranged in any suitable location, e.g. in the bottom of the humidifier <NUM> and/or in a side wall of the housing <NUM> of the humidifier <NUM>. The fan <NUM> is fluidly connected to the evaporation chamber <NUM>, e.g. through a conduit <NUM>, and is adapted to generate an air stream as indicated by the block arrows through the evaporation chamber <NUM> in a direction from the tray <NUM> including the nebulizer <NUM> towards an impactor <NUM> under a roof <NUM> of the humidifier <NUM> through which the air stream is expelled into the ambient surroundings of the humidifier <NUM> by means of an outlet downstream of the impactor.

The evaporation chamber may instead directly couple to the outlet if an impactor is not needed.

During transport from the nebulizing device <NUM> to the impactor <NUM>, at least some of the water droplets generated by the nebulizing device <NUM> may at least partially evaporate in the evaporation chamber <NUM> before reaching the impactor <NUM>. In examples, the fan <NUM> produces an air flow at a rate of <NUM>-<NUM><NUM>/h although other air flow rates are equally feasible depending on the size and application domain of the humidifier <NUM>.

The nebulizing device <NUM> may be any suitable type of nebulizing device. In an example, which is schematically depicted in <FIG>, the nebulizing device <NUM> comprises a piezoelectric mesh <NUM> driven by an actuator <NUM>. The piezoelectric mesh during use is brought into contact with a volume of water <NUM> from the tray <NUM>. The piezoelectric mesh <NUM> typically comprises a plurality of holes <NUM> having a defined diameter to control the size of the water droplets generated with the piezoelectric mesh <NUM>. For example, the holes or pores <NUM> may be laser-drilled in a flexible metal sheet or the like, such that the holes or pores <NUM> have well-defined diameters to establish tight control over the size of the water droplets generated with the piezoelectric mesh <NUM>, e.g. holes or pores <NUM> having a diameter in a range of <NUM>-<NUM>, e.g. in a range of <NUM>-<NUM>, for generating water droplets of correlated size. During operation, which is schematically depicted in <FIG>, the actuator <NUM> causes the piezoelectric mesh <NUM> to vibrate, thereby forcing a column <NUM> of water through the holes <NUM> when the piezoelectric mesh <NUM> is flexed towards the water volume <NUM> and expelling the column <NUM> of water in the form of droplets <NUM> when the piezoelectric mesh <NUM> is flexed away from the water column <NUM>. It is noted for the avoidance of doubt that during normal use of the nebulizer <NUM>, the volume <NUM> of water is typically located below the piezoelectric mesh <NUM> such that the water droplets <NUM> are expelled upwardly from the piezoelectric mesh <NUM> into the evaporation chamber <NUM>.

The actuator <NUM> may be adapted to vary the vibration frequency and amplitude of the piezoelectric mesh <NUM>, which for example may be achieved by varying the voltage or pulse width supplied by a pulse width modulated actuator <NUM>. To this end, the humidifier <NUM> may have a user interface (not shown) through which a user can set a water nebulization rate of the nebulizing device <NUM>, directly or indirectly, which rate setting translates to a corresponding adjustment of the vibration frequency, amplitude or duty cycle of the piezoelectric mesh <NUM>. In an example, the water nebulization rate of the nebulizing device <NUM> is at least <NUM>/h to ensure sufficient humidifying of an enclosed space, e.g. a room or the like, in which the humidifier <NUM> is to be placed.

The design does not need a sponge or pump to provide water from the water reservoir. For completeness, an example is schematically depicted in <FIG> in which the nebulizing device <NUM> comprises a chamber <NUM> containing a sponge <NUM> or the like such that water from the tray <NUM> can be absorbed by the sponge <NUM> through an aperture <NUM> in the housing <NUM> of the chamber <NUM>. A spring <NUM> may be located at the bottom of the chamber <NUM> to press the sponge <NUM> against the piezoelectric mesh <NUM> such that the piezoelectric mesh <NUM> has access to the volume <NUM> of water provided by the sponge <NUM>. To this end, the sponge <NUM> should have a water absorption rate at least matching the water nebulization rate of the nebulizing device <NUM>. Preferably, the chamber <NUM> may be opened such that the sponge <NUM> can be removed from the chamber <NUM>, e.g. for cleaning or replacement purposes, as over time the sponge <NUM> may become dirty, especially when tap water is used in the tray <NUM>. The nebulizing device <NUM> may be secured in the tray <NUM> in any suitable manner. For example, the tray <NUM> may comprise a holder <NUM> or the like that engages with the nebulizing device <NUM> to keep it in place within the tray <NUM>. Other suitable solutions will be immediately apparent to the skilled person. Of course, the design of the nebulizing device <NUM> is not particularly limited and any suitable nebulizing device <NUM> may be used for the humidifier <NUM>. As such alternative nebulizing devices are well-known per se, this will not be explained in further detail for the sake of brevity only.

As explained above, the nebulizing device <NUM> produces water droplets <NUM> that are carried by the air stream produced by the fan <NUM> through the evaporation chamber <NUM> during which the water droplets <NUM> may at least partially evaporate during transport through the evaporation chamber <NUM>. At the end of the evaporation chamber <NUM> distal to the tray <NUM>, an impactor <NUM> is arranged that is adapted to capture the water droplets <NUM> that are still present in the air stream at that point. The impactor <NUM>, which is schematically depicted in <FIG>, comprises an inner body <NUM> facing the evaporation chamber, which inner body <NUM> comprises a plurality of apertures <NUM> in the material <NUM> of the inner body <NUM>, which apertures <NUM> are dimensioned to block water droplets above a particular from passing through the inner body <NUM> of the impactor <NUM>.

The impactor <NUM> further comprises an outer body <NUM> arranged such that the inner body <NUM> is located in between the evaporation chamber <NUM> and the outer body <NUM>. The outer body <NUM> comprises a plurality of further apertures <NUM> in the material <NUM> of the outer body <NUM>, which further apertures <NUM> are offset relative to the apertures <NUM> such that each aperture <NUM> faces a material section <NUM> of the outer body that is spatially separated from the aperture <NUM>. The inner body <NUM> and the outer body <NUM> are typically arranged such that each aperture <NUM> is fluidly coupled to at least one of the further apertures <NUM>, that is, an air flow path exists between each aperture <NUM> and at least one of the further apertures <NUM>, e.g. by spatially separating the inner body <NUM> from the outer body <NUM>. In operation, when the air stream generated by the fan <NUM> (as indicated by the curved arrows) is forced through the apertures <NUM> of the inner body <NUM>, the air stream is accelerated due to this force caused by the relatively small dimensions of the apertures <NUM>, and diverted once the air stream has passed through the apertures <NUM> due to the offset positioning of the further apertures <NUM> relative to the apertures <NUM>, as indicated by the curved arrows in <FIG>. However, due to their moment of inertia, small water a2 passing through an aperture <NUM> cannot divert quickly enough to reach one of the further apertures <NUM> and collide with the material section <NUM> of the outer body <NUM> instead, such that only water vapour carried by the air stream can escape the impactor <NUM> and the humidifier <NUM> as a consequence, thereby preventing contaminants that are typically contained by water droplets <NUM> from entering the ambient environment of the humidifier <NUM>. To this end, the material portion <NUM> is preferably spatially separated from an opposing aperture <NUM> by a distance in a range of <NUM>-<NUM> although other distances may also be suitable, e.g. depending on the air flow rate generated by the fan <NUM>.

The material sections <NUM> of the outer body <NUM> may further comprise one or more sidewalls <NUM> extending along the further apertures <NUM> towards the inner body <NUM> to improve the droplet capturing capability of the outer body <NUM>. Although such sidewalls <NUM> preferably are spatially separated from the inner body <NUM>, one of the sidewalls <NUM> of each material section <NUM> may instead extend onto the inner body <NUM>, e.g. to strengthen the impactor <NUM>, in which case each aperture <NUM> is typically connected to one or more further apertures <NUM> on one side of such a material section <NUM> only.

<FIG> shows relevant dimensions of the impactor <NUM>. In an example, these dimensions were chosen as per Table <NUM> below.

The values in Table <NUM> are applicable for an impactor <NUM> used in a humidifier <NUM> deploying a nebulizing device <NUM> producing water droplets having a diameter in a range of <NUM>-<NUM> and a fan <NUM> producing an air flow rate of around <NUM>-<NUM><NUM>/h. Of course, it will be readily understood by the skilled person that the values of these parameters are shown by way of non-limiting example only, and may readily be adjusted if at least one of the droplet size produced by the nebulizing device <NUM> and the air flow rate produced by the fan <NUM> is adjusted.

<FIG> is an exploded view of an impactor <NUM> according to an example, in which both the inner body <NUM> and the outer body <NUM> have a cylindrical shape with the cylinder of the outer body <NUM> having a larger diameter than the cylinder of the inner body <NUM> such that the inner body <NUM> fits within the outer body <NUM> as schematically depicted in <FIG>. In this example, the apertures <NUM> are grouped in linear arrays of apertures <NUM> that extend between the opposing edges of the cylindrical body <NUM>. The further apertures <NUM> are shaped as elongate slots or channels that extend in the same direction as the linear arrays of apertures <NUM>, i.e. between the opposing edges of the cylindrical outer body <NUM>, which has the advantage that once the air stream generated by the fan <NUM> has passed through the further apertures <NUM>, this air stream can pass through the channel-shaped further apertures <NUM> relatively unrestrictedly. Moreover, shaping the further apertures <NUM> in the form of slots or channels simplifies the manufacture of the outer body <NUM>, thus reducing its cost. Of course, the impactor <NUM> is not limited to a cylindrical shape. Other shapes, e.g. a cuboid shape, are equally feasible, and may simply be chosen such as to match the shape of the housing <NUM> of the humidifier <NUM>.

<FIG> shows a bottom view of an impactor <NUM> according to an example, in which the impactor <NUM> further comprises drainage holes <NUM>, which drainage holes <NUM> are arranged to drain water droplets <NUM> that are captured on the surface of the material sections <NUM> of the outer body <NUM> from the impactor <NUM>. The drainage holes <NUM> for example may be located in a partition between the inner body <NUM> and the outer body <NUM>, or may be incorporated into the design of the impactor <NUM> in any other suitable manner. In order to promote water drainage from the impactor <NUM>, the inner body <NUM> and the outer body <NUM> may be hydrophobic, e.g. each of the inner body <NUM> and the outer body <NUM> may be made of a hydrophobic material such as a hydrophobic polymer, or may be coated with a hydrophobic layer such as hydrophobic polymer layer. As such hydrophobic materials are well-known per se, this will not be explained in further detail for the sake of brevity only.

Now, upon returning to <FIG>, the humidifier <NUM> may further comprise one or more drainage channels <NUM> that extend from the impactor <NUM> towards the tray <NUM> such that water droplets <NUM> captured by the impactor <NUM>, e.g. in between the inner body <NUM> and the outer body <NUM> may be returned to the tray <NUM>. To this end, the drainage holes <NUM> of the impactor <NUM> are typically aligned with the at least one drainage channel <NUM> such that water drained from the impactor <NUM> through the drainage holes <NUM> is fed into the at least one drainage channel <NUM>. The one or more drainage channels <NUM> may be hydrophobic, e.g. made from or coated with a hydrophobic material, to promote return of water drained from the impactor <NUM> to the tray <NUM>.

The humidifier design described above is based on the combination of a nebulizer <NUM> and an impactor <NUM> with an evaporation chamber <NUM> between them.

The impactor is however optional, and this invention relates instead generally to a humidifier design with nebulizer in contact with a water supply, the nebulizer feeding to an evaporation chamber.

The invention provides a modification to this general design, and in particular it relates to the way water is supplied to the nebulizer <NUM>. In the example above, the nebulizer <NUM> is set in a tray <NUM> which is supplied with water from the reservoir <NUM>.

<FIG> shows the invention implemented as a modification to the design of <FIG> (i.e. having the optional impactor), in which the nebulizer <NUM> is arranged to float on the surface of the water in the tray, and hence follow the water level in the tray.

In this way, there is no need for a separate reservoir; the tray can be a deep tray (i.e. it is itself the reservoir) to house the desired quantity of water with the nebulizer <NUM> floating on top, and the nebulizer lowers vertically as the water is used up.

The nebulizer <NUM> can be a single nebulizer element or an array of multiple nebulizer elements, depending on the requirements for production rate. Multiple nebulizer elements may also be provided for the purposes of providing redundant parts, to extend the lifetime of the device. Each nebulizer element may be a vibrating mesh as described above.

<FIG> shoes the nebulizer <NUM> more clearly floating on the water <NUM>.

<FIG> shows an example of the nebulizer in more detail.

The nebulizer comprises a pre-filter <NUM>, a float <NUM> over the pre-filter and a nebulizer holder <NUM> on top of the float <NUM>.

The pre-filter removes the microorganisms and large particles in the water. As the nebulizer uses for example <NUM> hole size, the pollution inside the water larger than <NUM> diameter can easily block the nebulizer pores. As a result, the filter hole size is below <NUM>, typically <NUM>-<NUM>. The pre-filter material is for example stainless steel (<NUM> or <NUM>) to prevent corrosion.

The nebulizer holder defines a set of nebulizer nozzles <NUM>. A location pin <NUM> acts as a guide to allow the nebulizer to rise and fall with the water level. The location pin controls the nebulizer array position, so that the nebulizer (with its array of nozzles) will move up and down vertically.

The individual nebulizer nozzles <NUM> are installed on the nebulizer holder <NUM> with a tilt angle (to the horizontal), typically in the range <NUM>°- <NUM>°. In this way, water dripping from the ceiling <NUM> (<FIG>) can easily fall back to the water tray through without water draining openings <NUM> without blocking the nebulizer.

The float is made from a low density material and assembled with the nebulizer holder, to ensure the correct position on top of the water. The pre-filter is also attached to the float.

<FIG> also shows cable connectors <NUM>. The nebulizer connects to a cable connector on the location pin. A cable goes through the location pin <NUM> to the nebulizer driving board(s).

The nebulizer nozzles <NUM> are installed in a circular form.

As mentioned above, the structure also has a tilt angle, typically <NUM>°-<NUM>°, and a water drainage directly to the water tray, without passing through the filter. When the water level changes, the float nebulizer system moves accordingly and the nebulizer can always remain in contact with the water and produce droplets. Water from the water tray passes through the metal pre-filter to reach the mesh nebulizers as a source for aerosolization.

<FIG> shows the nebulizer structure in exploded form. Drainage openings <NUM> of the pre-filter <NUM> can be seen in addition to the general mesh structure of the pre-filter.

Claim 1:
A humidifier (<NUM>) comprising:
a water containing arrangement (<NUM>) for containing water and a nebulizing device (<NUM>) for nebulizing water from said water containing arrangement;
an evaporation chamber (<NUM>) arranged over said nebulizing device; and
a fan (<NUM>) arranged to generate an air flow (<NUM>) through said evaporation chamber towards an outlet,
wherein the nebulizing device is configured to float on the surface of the water (<NUM>) in the water containing arrangement, and characterized in that: the nebulizing device comprises a float (<NUM>), with a pre-filter (<NUM>) at the base of the float and the nebulizing device comprises at least one nebulizing element (<NUM>) at a top of the float.