Patent Description:
Breathing treatment devices typically include an airflow generator to supply pressurized breathing gases. In some breathing treatment devices, an integrated water supply chamber may be provided. The water chamber can include a supply of water that is used to humidify the breathing gases that are being supplied by the breathing treatment device.

In some configurations, the breathing treatment devices are designed to be portable and/or movable. When such devices are moved while containing water in a water supply reservoir, the reservoir may tip and allow water to spill from the water reservoir into other regions of the breathing treatment devices. Where the device is formed of many separate parts, there is a risk that water could seep between parts and damage electronic components within the device.

In some configurations, the breathing treatment devices may comprise one or more sensors at various locations within the device, which may make it difficult to service these sensors.

The present invention may go at least some way towards reducing the risk that electronic components within a breathing treatment device, such as a CPAP machine, may be damaged as a result of liquid leaking into the device.

<CIT> relates to breathing assistance apparatus having a humidification compartment defined within a main body and is adapted to receive a humidification chamber. A flow generator is also positioned within the main body. The flow generator and the humidification compartment are fluidly connected via a liquid containment compartment which is interposed between the flow generator and the humidification compartment. The liquid containment compartment prevents water spills from the humidification chamber from reaching other areas of the breathing assistance apparatus.

<CIT> relates to a respiratory assistance apparatus including a flow generator and a humidifier. The humidifier includes a humidification chamber. The humidification chamber comprises a water tub that is configured to receive a volume of water. A lid is hingedly coupled to the water tub for enclosing a volume contained within the water tub.

<CIT> relates to a blower unit for use as part of an integrated blower/humidification system. The blower unit has an outer casing, which encloses and forms part of the blower unit, the casing including an air inlet vent. The blower unit further includes a humidifier compartment for receiving a humidifier unit with a separate gases inlet and outlet, the compartment having a heater base for heating the contents of the humidifier unit. The compartment also has a blower inlet port which aligns with the humidifier unit inlet in use, the blower providing a gases path through the casing between the inlet vent and the inlet port. The blower unit also includes a fan for providing a pressurised gases stream along the gases path, and a power supply unit for powering the fan. The gases path is routed over the power supply unit in order to provide a cooling air flow.

CPAP machines include an airflow generator to supply pressurized gas to a user. Many CPAP machines include a heated water bath or other source of water for humidification of the pressurized gas. CPAP machines are often used in bedrooms or other sleeping quarters and are placed on nightstands, for example. As such, it may be desirable for the CPAP machine to look aesthetically pleasing. It may also be desirable for the CPAP machine to be substantially stable when placed on a supporting surface, such as on a nightstand. It may also be desirable for CPAP machines to be easily refilled with water, and to be moved when containing water, with minimum risk of spills that may cause water damage to the sensitive electronic components within the machine. CPAP machines may also need to be serviced from time to time and so it may be useful for the key components of the machine to be readily accessible for servicing.

It is provided a breathing assistance apparatus for the delivery of breathing gas to a user, wherein the apparatus comprises a body and a lid, wherein the body comprises at least one housing comprising at least one outer wall; at least one inner wall substantially adjacent to and spaced apart from the outer wall; and an upper surface spanning between upper edges of the at least one outer and inner wall, wherein the outer and inner walls and upper surface are integrally formed as one part.

Preferably, the inner wall forms an enclosure for a humidification chamber, and the lid covers the enclosure. Optionally, a heating element is located in an aperture of the lower wall of the enclosure.

In one form, the outer and inner walls may be formed without seams or joins. In one form, the breathing assistance apparatus may comprise four inner walls and three outer walls, wherein the three outer walls are located substantially adjacent to and spaced apart from three of the four inner walls. A face plate may be located substantially adjacent to the remaining inner wall. The face plate may comprise a user interface through which a user may control the apparatus.

Preferably, the body of the at least one housing comprises three inner walls and three outer walls, each outer wall being substantially adjacent to and spaced apart from a respective one of the three inner walls; and wherein the housing further comprises a fourth inner wall and a face plate located substantially adjacent to and spaced apart from the fourth inner wall to form an outer wall of the housing. Optionally, substantially the whole of the face plate is tinted.

In one form, the apparatus further comprises a printed circuit board (PCB) located within the at least one housing and positioned behind the face plate, wherein the apparatus further comprises a compressible facing comprising a first portion located between the PCB and face plate and a second portion located between the PCB and interior structures of the housing to provide damping to both faces of the PCB. Preferably, the PCB comprises one or more apertures through which arms of the compressible facing may project so that the PCB is supported by the compressible facing. Optionally, the first portion of the compressible facing comprises one or more apertures that substantially align with LED lit components located on the PCB.

In one form, the apparatus comprises an upper housing, a lower housing and a base, wherein the lower housing is connected to both the upper housing and the base, and wherein the face plate forms an outer wall for at least the upper housing and lower housing.

In one form, the apparatus comprises two or more sensors located on one face of the PCB and wherein the apparatus further comprises an interior wall comprising two or more apertures that substantially align with the sensors, such that the sensors may be caused to project through the apertures in the interior wall and into an air flow path located within the apparatus, by pushing the PCB against interior wall. Optionally, the apertures comprise soft seals around walls of the apertures and the soft seals are co-molded to the interior wall of the apparatus.

It is provided a breathing assistance apparatus for the delivery of breathing gas to a user, wherein the apparatus comprises two or more sensors located on one face of a PCB and wherein the apparatus further comprises an interior wall comprising two or more apertures that substantially align with the sensors, such that the sensors may be caused to project through the apertures in the interior wall and into an air flow path located within the apparatus, by pushing the PCB against interior wall. Preferably, the interior wall is a wall of an air flow path. In this form, the sensors may project through apertures in the interior wall and into the air flow path.

Preferably, the apertures comprise soft seals around walls of the apertures and the soft seals are co-molded to the interior wall of the apparatus.

It is provided a breathing assistance apparatus for the delivery of breathing gas to a user, wherein the apparatus comprises: a heating element for heating a humidification chamber; a control system comprising a first electronic protection circuit connected to the heating element and comprising: a first temperature sensor configured to sense the temperature of the heating element and produce outputs based on the sensed temperature; a first comparator circuit; a first switching member; and a programmable control unit; wherein the first comparator circuit is configured to receive outputs from the first temperature sensor and compare those outputs with a first predetermined temperature threshold T1 to determine if the heater plate temperature exceeds the first predetermined temperature threshold T1 and to cause the first switching member to disable power to the heating element when the sensed heating element temperature exceeds the first predetermined threshold temperature T1 and wherein the programmable control unit is configured to receive outputs from the first temperature sensor and to cause the first switching member to disable power to the heating element when the sensed heating element temperature exceeds a first predetermined programmed threshold temperature, which may be equal to or greater than T1.

Optionally, the first switching member is an electronically controlled switch configured to disable power to the heating element by electronically breaking the electronic circuit to the heating element.

Alternatively, the first switching member is an electronically controlled moveable switch configured to disable power to the heating element by moving from a first position to a second position to physically break the electronic circuit to the heating element.

In one form, the control system further comprises: a second electronic protection circuit comprising: a second temperature sensor configured to sense the temperature of the heating element and produce outputs based on the sensed temperature; a second comparator circuit; and a second switching member wherein the second comparator circuit is configured to receive outputs from the second temperature sensor and compare those outputs with a second predetermined threshold temperature T2 to determine if the heater plate temperature exceeds the second predetermined temperature threshold T2 and to cause the second switching member to disable power to the heating element when the sensed heating element temperature exceeds the second predetermined threshold temperature T2, which may be equal to or greater than T1.

Optionally, the programmable control unit is configured to receive temperature outputs from the second temperature sensor and to cause the second switching member to disable power to the heating element when the sensed heating element temperature exceeds a second predetermined programmed threshold temperature, which may be equal to or greater than T2.

In one form, the programmable control unit is configured to receive outputs from the first and second temperature sensors and calculate a control unit sensed temperature by averaging the outputs of the first and second temperature sensors and to then compare the control unit sensed temperature to the first predetermined programmed temperature and to the second predetermined programmed temperature and cause the first or second switching member to disable power to the heating element if the control unit sensed temperature exceeds of the first or second predetermined programmed temperatures.

In one form, the control unit is configured to cause the switching member(s) to disable power to the heating element if the control unit sensed temperature exceeds the first or second predetermined programmed temperature threshold for a predetermined period of time.

In one form, the second switching member is an electronically controlled moveable switch configured to disable power to the heating element by moving from a first position to a second position to physically break the electronic circuit to the heating element.

In one form, the control unit is configured to identify the difference in outputs of the first and second temperature sensors and to cause the switching member(s) to disable power to the heating element when the control unit identifies that the outputs of the first and second temperature sensors differ by a predetermined threshold.

It is provided a method of manufacturing a plastic housing for the breathing assistance apparatus of the disclosure and comprising the step of injection moulding the plastic housing by configuring an injection moulding machine so that its gates are located at diametrically opposed corners of the upper surface of the housing.

Because of the cramped spaces in which CPAP machines are used, easy manipulation of a lid or other component used to enclose a water reservoir or the like is desired. Preferably, the lid or other such component can be easily pivoted about hinges.

Moreover, to improve the ability to access the water reservoir, the lid preferably carries a locking mechanism that is configured to allow a user to release the lock and open the lid with a single hand, preferably, with the single hand in a single position. Such configurations are a welcomed improvement over configurations requiring one hand to operate the lock and another hand to subsequently raise the lid.

These and other features, aspects and advantages of the present disclosure will be described with reference to preferred embodiments shown in the following drawings, in which:.

<FIG> illustrates a breathing assistance apparatus <NUM> that is arranged and configured in accordance with certain features, aspects and advantages of the present invention. <FIG> shows one form of breathing assistance apparatus <NUM> connected to a breathing tube <NUM> and an interfacing structure <NUM>. In the embodiment illustrated, the interfacing structure <NUM> is a mask, but the breathing assistance apparatus <NUM> of the invention may be used with any suitable form of interfacing structure, including a nasal cannula or nasal pillows, for example.

In one form, as shown in <FIG>, the breathing apparatus <NUM> is a CPAP machine that includes a housing comprising a body <NUM> and a lid <NUM>. The body <NUM> may be configured to house a humidification chamber with water reservoir, a heating element, a blower, and an electronic system that connects a user interface to electronic components of the CPAP machine <NUM>.

In one form, as shown in <FIG>, the body <NUM> may comprise an upper housing <NUM>, a lower housing <NUM> positioned beneath the upper housing <NUM>, and a base <NUM> positioned beneath the lower housing <NUM>.

The upper housing <NUM> may be configured to house a humidification chamber. In one form, the upper housing <NUM> comprises heating element that, in use, contacts the base of the humidification chamber to heat water within the chamber. Optionally, the heating element may be located within an opening or recess formed in a bottom portion of the upper housing <NUM>.

A lid <NUM> covers the upper housing <NUM> to substantially enclose the humidification chamber within the housing <NUM>. In one form, the lid <NUM> may be formed of plastic and may be at least about <NUM> thick throughout a significant portion of the lid <NUM> and preferably through substantially the whole of the lid <NUM>. In this configuration, the thickness of the lid <NUM> provides the lid <NUM> with additional strength whilst allowing the upper exterior surface <NUM> of the lid <NUM> to maintain a substantially smooth and aesthetically appealing appearance. Reinforcing ribs <NUM> may be placed on the lower inner surface <NUM> of the lid <NUM> to further help reinforce and strengthen the lid <NUM>. In some forms, the ribs <NUM> tend to distort the upper surface <NUM> of the lid and the result can be unattractive. A lid having a thickness of about <NUM> may reduce any distortion to the upper surface from the reinforcing ribs <NUM>.

The lid <NUM> may be configured to be removable from the body <NUM> or the lid <NUM> may be hinged or otherwise connected to the body <NUM> of the apparatus <NUM> to allow access to the interior of the upper housing <NUM>.

In one form, the lid <NUM> is connected to the body <NUM> with hinge assemblies <NUM>. In the illustrated configuration, the lid <NUM> is connected to the rear of the body <NUM> using two hinge assemblies. The lid <NUM> can be connected to other surfaces. In addition, the lid <NUM> can be connected to the body <NUM> using as few as one hinge assembly <NUM> or more than two hinge assemblies <NUM>. Preferably, the hinge assemblies <NUM> are constructed such that, with the lid <NUM> in the closed position (e.g., as shown in <FIG>), the hinge assemblies <NUM> are generally flush with or recessed into the surface of the rear outer wall 132b. In some configurations, the hinge assemblies <NUM> are constructed such that the hinge assemblies do not protrude rearward of the rear outer wall surface 132b. In some configurations, some of the hinge features may protrude very slightly from one or more surrounding surface of the rear outer wall surface or other surrounding portion of the apparatus. In some configurations, the lid <NUM> comprises an outer perimeter and the hinge assemblies <NUM> do not protrude significantly outward of the outer perimeter of the lid <NUM>.

As shown in <FIG>, the lid <NUM> may comprise a handle <NUM> for easy maneuverability. Preferably, the handle <NUM> is located substantially centrally on the lid <NUM>, but in other forms the handle <NUM> may be located further toward the front or rear of the lid <NUM> or even to one side of the lid <NUM>. In one form, the handle <NUM> is hinged from the lid and is configured to move between a down position (such as a storage position) and a raised position in which the handle projects from the lid and is able to be held by a user in order to carry the apparatus. The handle may comprise a first surface 126a and a substantially opposing second surface. When the handle is in the down position, the first surface 126a may form an upper surface 126a that is substantially flush with or that is below the upper surface <NUM> of the lid <NUM>. Therefore, when the handle <NUM> is in the down position, the apparatus <NUM> may be substantially devoid of protrusions extending from its upper surface <NUM>.

By providing a breathing assistance apparatus <NUM> having a substantially flush upper surface <NUM> or an upper surface <NUM> that is at least substantially devoid of protrusions, the apparatus <NUM> may be kept substantially compact in order to take up minimal space during transportation and to reduce the risk of damage to otherwise protruding parts. The apparatus <NUM> may also be more aesthetically pleasing.

It has been found that hinged handles may sometimes squeak as the handle is moved between a down position and a raised position. To minimise squeaking of the handle <NUM> when it is moved, the handle <NUM> may be formed of a different material to the lid <NUM> or at least the hinge members of the handle <NUM> (that connect engage with hinged members of the lid to form a hinge) may be formed of a different material to the connecting hinged members 125a of the lid <NUM>. For example, the handle <NUM> or hinged members of the handle may be substantially formed of a polyester material and the lid or hinged members of the lid may be substantially formed of a polycarbonate material. One or more grooves <NUM> may also be provided on the hinged members 125a of the lid to further minimize squeaking, as shown in <FIG> and <FIG>.

Optionally, the lid <NUM> may also comprise one or more locks <NUM> to lock the lid <NUM> in the closed position. In one form, the lid <NUM> is hinged from the rear of the apparatus <NUM> and a lock, which comprises a latch <NUM>, is provided at the front of the apparatus <NUM> to hold the lid <NUM> closed. Preferably, the latch <NUM> is provided at a central region at the front of an upper edge of the apparatus body <NUM>. In this form, because only a central latch is provided (rather than a latch on either side of the lid), the lid may tend to rock from side to side. This may cause the apparatus <NUM>, particularly the upper housing <NUM>, to leak. To help prevent the lid <NUM> from rocking in this manner, one or more support members <NUM> may be provided between the lid and apparatus body. The support member(s) <NUM> may be configured to keep the lid substantially level with or substantially parallel to an upper surface of the apparatus body <NUM>, such as an upper surface of the upper housing. In one form, the support member(s) <NUM> may be provided on the interior surface of the lid <NUM> at or near each front corner and/or the support member(s) <NUM> may be provided on an upper surface of the upper housing <NUM> at or near each front corner. In one form, the one or more support members <NUM> may be in the form of ridges or rails or the like that project from the interior surface at each front corner of the lid, as shown in <FIG>. The support member(s) <NUM> may also help to prevent the lid from rocking side to side during use.

The illustrated body <NUM> of the apparatus comprises at least one outer surface <NUM>. In the illustrated configuration, the body <NUM> comprises four generally planar outer surfaces <NUM> that are connected by rounded corners <NUM>. Other configurations are possible.

As shown in <FIG>, the outer surface(s) of the body typically form(s) outer wall(s) of the upper and lower housings <NUM>, <NUM> and base <NUM>.

The upper housing <NUM> may comprise at least one inner wall <NUM> that defines an inner surface of the upper housing and at least one outer wall <NUM> that defines an outer surface of the upper housing. For example, the upper housing may comprise a substantially circular inner wall that is substantially adjacent to a substantially circular outer wall. In another form, the upper housing may comprise a plurality of inner walls and outer walls.

The inner wall <NUM> may comprise an inner surface that faces the interior of the upper housing <NUM> and an outer surface that faces away from the interior. Similarly, the outer wall <NUM> may comprise an inner surface that faces toward the interior of the upper housing <NUM> and an outer surface that faces away from the interior.

The inner <NUM> and outer wall(s) <NUM> may be integrally formed as a single part to avoid seams or joins between the walls <NUM>, <NUM>. In one form, the inner wall(s) <NUM> may be located substantially adjacent to and spaced apart from the outer wall(s) <NUM> so that the outer surface of the inner wall <NUM> substantially faces the inner surface of the outer wall <NUM>. As shown in <FIG>, an upper surface <NUM> may be provided at or near an upper edge of the inner <NUM> and outer <NUM> walls and may span the distance between upper edges of the inner and outer walls <NUM>, <NUM>. In one form, the inner and outer walls <NUM>, <NUM> are configured so that the inner wall(s) <NUM> appear(s) to be substantially folded back on the outer wall(s) <NUM>. In this form, the upper surface <NUM> that joins the inner and outer walls <NUM>, <NUM> also forms a 'folded' region. By providing an upper housing <NUM> having inner and outer walls <NUM>, <NUM> without a seam or join between the walls <NUM>, <NUM>, it is possible to reduce the risk that water or other liquids may seep between the join and enter into the lower housing <NUM> below.

In one form, the upper housing <NUM> may comprise at least three inner walls forming substantially opposing inner side walls 131a, 131c, an inner rear wall 131b extending between the inner side walls and an inner front wall 131d that substantially opposes the inner rear wall 131b. A lower wall <NUM> may be connected to and located between the inner walls 131a, 131b, 131c, and 131d to form the floor of the upper housing. In this configuration, the upper housing <NUM> may form an enclosure for a humidification chamber. Optionally, an opening or recess 134a may be provided in the lower wall <NUM> for locating a heating element therein, as shown in <FIG>. Preferably, the heating element is supported by a sub-housing <NUM> that is located beneath the opening 134a. The sub-housing <NUM> may be an internal structure that is configured to be located between the upper and lower housings <NUM>, <NUM>. In one form, the sub-housing <NUM> may be configured to comprise a floor that substantially extends across and below the opening 134a, as shown in <FIG>, to support the heating element and humidification chamber thereon.

In one form, the floor of the sub-housing <NUM> comprises a recessed region <NUM> configured to be located beneath the opening 134a of the upper housing <NUM> when the apparatus <NUM> is assembled. Preferably, the recessed region <NUM> is wider than the opening 134a so that a channel <NUM> is formed between a lower surface of the recessed region <NUM> and a bottom surface of the upper housing floor <NUM>. The periphery of the recessed region <NUM> may form an outer wall <NUM> of the channel <NUM>. Optionally, a peripheral wall <NUM> substantially surrounds the opening 134a and projects downwardly from the bottom surface of the upper housing floor <NUM> and a gap is formed between the distal end of the peripheral wall <NUM> and the recessed region <NUM>. The channel <NUM> formed between the peripheral wall <NUM>, outer wall <NUM>, and recess region <NUM> may be configured to hold an outer edge of a heating element therein to help hold the heating element in position. A humidification chamber (not shown) may be located above the heating element and may be substantially held in position by inner walls that define the opening 134a in the floor of the upper housing <NUM>.

The shape of the exterior of the upper housing <NUM> may be similar to that of its interior. For example, the exterior of the upper housing <NUM> may comprise three outer walls forming substantially opposing outer side walls 132a, 132c and an outer rear wall 132b extending between the outer side walls 132a, 132c. The outer side walls 132a, 132c, and rear wall 132b may be located substantially adjacent to and spaced apart from the inner side walls 131a, 131c and rear wall 131b respectively to form three pairs of inner and outer walls. In this configuration, a gap <NUM> is provided at the front of the upper housing <NUM> between the outer side walls 132a, 132c.

A face plate <NUM> may be located within the gap <NUM> between the outer side walls 132a, 132c. For example, a face plate may be located substantially adjacent to the unpaired inner front wall 131d. In one form, the face plate <NUM> may substantially extend from one front corner of the upper housing <NUM> to the other front corner. The face plate <NUM> may comprise a user interface through which a user may control the apparatus <NUM>.

Although in a preferred form, the upper housing <NUM> comprises four inner walls <NUM> and three outer walls <NUM>, as described above, it is envisaged that other configurations are possible.

Turning now to <FIG> and <FIG>, the lower housing <NUM> may comprise at least one inner wall <NUM> that defines an inner surface of the lower housing and at least one outer wall <NUM> that defines an outer surface of the lower housing. The inner wall <NUM> may comprise an inner surface that faces the interior of the lower housing <NUM> and an outer surface that faces away from the interior. Similarly, the outer wall <NUM> may comprise an inner surface that faces toward the interior of the lower housing <NUM> and an outer surface that faces away from the interior.

As described above and shown in <FIG>, to help prevent water or other forms of liquid entering a join between the inner and outer wall(s) of the lower housing <NUM> and into the base below, the adjacent inner <NUM> and outer <NUM> wall(s) of the lower housing <NUM> may be integrally formed as a single part. For example, the inner wall(s) <NUM> may be located substantially adjacent to and spaced apart from the outer wall(s) <NUM> so that the outer surface of the inner wall <NUM> substantially faces the inner surface of the outer wall <NUM>. An upper surface <NUM> may be provided at or near an upper edge of the inner <NUM> and outer <NUM> walls. The upper surface <NUM> may span the distance between upper edges of the inner and outer walls <NUM>, <NUM>. In one form, the inner and outer walls <NUM>, <NUM> are configured so that the inner wall(s) <NUM> appear(s) to be folded back on the outer wall(s) <NUM>. In this form, the upper surface <NUM> that joins the inner and outer walls <NUM>, <NUM> also forms a 'folded' region.

As shown in <FIG> and <FIG>, the lower housing <NUM> may comprise inner <NUM> and outer <NUM> walls of the same or a similar configuration to the inner <NUM> and outer <NUM> walls of the upper housing <NUM>, as described above. For example, the lower housing may comprise a substantially circular inner wall that is substantially adjacent to a substantially circular outer wall.

In one form, the lower housing may also comprise four inner walls <NUM> comprising substantially opposing side walls 231a, 231c, a rear wall 231b extending between the side walls 231a, 231c and a front wall 231d substantially opposite the rear wall.

A lower wall <NUM> may be connected to and located between the inner walls <NUM> to form a floor of the lower housing <NUM>. In one form, as shown in <FIG>, outer walls <NUM> of the lower housing may extend below the floor of the housing. For example, the floor <NUM> may be located substantially near the top edge of the inner <NUM> and outer walls <NUM>. In one form, the distance between the top edge of the inner wall <NUM> and the floor <NUM> may be so small that the inner wall and upper surface <NUM> of the wall structure form a lip that substantially defines the periphery of the floor <NUM>. In one form, a recess <NUM> may be formed in the floor <NUM> of the lower housing for locating a blower therein. A raised lip <NUM> may also be formed in the floor <NUM> to define the periphery of the recess <NUM>. The blower (not shown) may be configured to blow breathing gas into the humidification chamber in order to humidify the gas.

In one form, the sub-housing <NUM> comprises a guide configured to rest on or engage with the raised lip <NUM> of the lower housing. Additionally, or alternatively, the sub-housing <NUM> may comprise an outer guide configured to engage with or rest on the upper surface <NUM> of the lower housing wall configuration in order to help located the sub-housing on the lower housing <NUM>.

The shape of the exterior of the lower housing <NUM> may be similar to that of its interior. For example, the exterior of the lower housing <NUM> may comprise three outer walls forming substantially opposing outer side walls 232a, 232c and an outer rear wall 232b extending between the outer side walls 232a, 232c. The outer side walls 232a, 232c, and rear wall 232b may be located substantially adjacent to and spaced apart from the inner side walls 231a, 231c and rear wall 231b respectively to form three pairs of inner and outer walls. In this configuration, a gap <NUM> is provided at the front of the upper housing <NUM> between the outer side walls 232a, 232c. A face plate <NUM> may be located within the gap to form a front surface of both the upper and lower housing. The face plate <NUM> may therefore form an outer wall for both the upper <NUM> and lower <NUM> housing or for just the upper housing <NUM> or just the lower housing <NUM>.

A seal may be located between an upper edge of the face plate <NUM> and the upper <NUM> or lower housing <NUM>, as the case may be, to help prevent water seeping between the face plate and housing. Preferably, the face plate <NUM> forms an outer wall for both the upper and lower housing <NUM>, <NUM> and a seal is located on the top edge of the face plate <NUM> and abuts an upper edge of the upper housing <NUM>.

In one form, the face plate <NUM> may be tinted in whole or in part. For example, only an outer border of the face plate <NUM> may be tinted. Alternatively, substantially the whole of the face plate <NUM> may be tinted. The face plate <NUM> may be configured to provide a user interface comprising one or more images and/or user inputs to monitor and/or control the operation of the breathing assistance apparatus <NUM>, as shown in <FIG>. In some forms, the face plate <NUM> may comprise a plastic or glass screen with a backlit display. An LED screen is located behind and visible through the tinted <NUM> face plate. In this form, the face plate <NUM> also acts as a screen for the user interface.

Where substantially the whole of the face plate <NUM> is tinted, it may appear that the screen is larger and more integral with the body <NUM> of the apparatus. This configuration may be aesthetically appealing. In this configuration, less aesthetically pleasing components, such as electronic components for example, that are located behind the face plate <NUM> may also be less visible or may not be visible at all. Furthermore, the face plate <NUM> may be configured to align tidily with the substantially opposing outer side walls of the apparatus <NUM> to form a substantially flush or aesthetically appealing join, as shown in <FIG>.

According to the present invention, the apparatus <NUM> comprises an electronic user interface in whole or in part. In this form, a PCB is located behind the face plate <NUM> to control the user inputs and/or to control illuminated images that may be visible through the face plate <NUM> during use. One or more user inputs <NUM> may comprise mechanical buttons, switches, dials, or the like that are electrically connected to the PCB and that project in part through apertures formed in the face plate for access by a user. Additionally or alternatively, one or more user inputs <NUM> may comprise electronic buttons or dials that may be operated using any suitable system, such as by capacitive sensing in which the buttons or dials may be activated by the user lightly touching the face plate, for example.

A substantially compressible facing may be located behind the face plate <NUM> so as to be sandwiched between the face plate <NUM> and the PCB. The facing may help provide damping to the PCB by absorbing at least part of an impact shock to the apparatus, particularly an impact to the face plate of the apparatus. In this way, the facing may help protect the electronic components of the PCB from damage if the face plate <NUM> were otherwise knocked against the PCB components. The facing may be formed of any suitably compressible material, such as rubber or silicone for example. The facing may comprise one or more apertures through which user inputs may project. Optionally, one or more apertures of the facing may align with one or more apertures of the face plate <NUM> so that user inputs may project from the PCB and through the aligned apertures for access by a user. In another form, the facing may comprise one or more apertures that align with an electronic component on the PCB that may be illuminated during use. For example, the facing may comprise an aperture that aligns with the screen of an LED lit electronic clock located on the PCB and visible through the face plate <NUM>.

In one form, the substantially compressible facing may comprise arms that extend through apertures formed in the PCB to press against an outer surface of the adjacent inner wall of the housing, such as the upper housing <NUM>, the lower housing <NUM>, or both the upper and lower housings <NUM>, <NUM>. For example, the facing may comprise a first portion located between the PCB and the face plate, a second portion located between the PCB and interior structures of the apparatus, and one or more arms that project through apertures in the PCB and connect the first and second portions of the facing. In this arrangement, the PCB may be supported by and easily attached to the facing. The compressible facing, extending from both the front and rear surfaces of the PCB may also help to protect the PCB from impact forces from both the front and rear.

In one form, as shown in <FIG>, a user input in the form of a power switch <NUM> is provided on the face plate <NUM> to power the apparatus <NUM> on or off. The power switch <NUM> may be located proximate to the locking latch <NUM> of the lid <NUM> to provide for one handed operation by a user. In this configuration, a user can close the lid <NUM> and move their thumb or finger downward to activate the power switch <NUM> to power the apparatus <NUM> on. This configuration may provide a quick and simple method for a user to operate the latch <NUM> and power switch with one hand. Similarly, the user can place their hand on the lid <NUM>, turn off the power button <NUM> to turn the apparatus <NUM> off and then move their thumb or finger to the latch <NUM> to release the latch <NUM> and open the lid <NUM>. Again, these steps may be carried out quickly and easily with one hand. These steps may be further simplified where the latch <NUM> may be released by a button and where the power switch <NUM> is in the form of a button that can be depressed to turn the apparatus <NUM> on or off. Preferably, the latch <NUM> is located substantially directly above the power switch <NUM> and within a distance in which a typical user's thumb may reach without substantially moving the user's hand. For example, the latch <NUM> may be located within about <NUM> of the power switch <NUM>. It should be appreciated that, although it is preferred for the power switch to be in the form of a button, it is envisaged that the power switch could otherwise be in the form of a lever switch, dial, or other suitable user input without departing from the invention.

In one form, as shown in <FIG> and <FIG>, the apparatus <NUM> may be configured so that one or more of the sensors <NUM> are located for easy accessibility in order to service or replace the sensors when required. For example, a humidity sensor 145a may be located near the outer wall structure of the apparatus and in an air flow path between the blower and the humidification chamber. Preferably, the humidity sensor 145a is located on the sub-housing substantially above the area indicated in <FIG>. By positioning the humidity sensor downstream of the blower and upstream of the humidification chamber, the readings of the humidity sensor 145a may be more accurate compared to when the sensor 145a is placed upstream of the blower. This is because exhaled air from the patient may return along the breathing gas flow path toward the blower and may cause the humidity of the breathing gas upstream of the humidification chamber to increase above humidity levels upstream of the blower.

Optionally, the apparatus comprises a baffle located within the air flow path between the humidity sensor 145a and the blower. The baffle may be configured so that air exiting the outlet of the blower may contact the humidity sensor 145a but is not aimed directly at the humidity sensor 145a. Preferably, the baffle <NUM> is located within the sub-housing. In one form, the baffle <NUM> comprises a substantially u-shaped wall that projects from an interior wall of the sub-housing <NUM> and into the air flow path. The humidity sensor may also project from the interior wall of the sub-housing <NUM> and may be located between the arms of the U. A gap may be provided between the floor of the air flow path and a lower edge of the baffle wall <NUM> so that air may pass through the gap and behind the baffle <NUM> where the humidity of the air may then be measured by the humidity sensor 145a. In another form, a gap may be provided between the ceiling of the air flow path and an upper edge of the baffle wall <NUM>. In yet another form, a first gap may be provided beneath the lower edge of the baffle wall and a second gap may be provided above the upper edge of the baffle wall. In these arrangements, air from the flow path is in contact with the humidity sensor 145a but is not blown directly at the sensor 145a, so that more accurate sensor readings may be obtained. In one form, the apparatus comprises a humidity sensor 145a, to measure the humidity of air, and a flow sensor 145c to measure air flow to provide an indication of how much power is provided to the heating plate. The flow sensor may be located in a venturi <NUM> through which air flows from an air inlet <NUM> to the blower. One suitable location for the flow sensor 145c is indicated in <FIG>.

Air exiting the blower may flow along a flowpath to the upper housing <NUM> and through a flowpath in the upper housing to an air inlet of the humidification chamber.

In one form, pressure and humidity sensors may be located in the sub-housing <NUM> and immediately downstream of the blower.

In one form, a pressure sensor 145b may be located in the sub-housing at a distance from the blower to reduce the likelihood that air flowing from the outlet of the blower could adversely affect the pressure readings, particularly as a result of fluctuations in the blower motor. By locating the pressure sensor 145b away from the flowpath of outlet air from the blower, it may be possible to obtain more accurate pressure readings. In a preferred arrangement, the pressure sensor 145b is located on the sub-housing <NUM> substantially above the area indicated in <FIG> and as shown in <FIG>.

According to the present invention, two or more sensors <NUM> are located on one face of the PCB <NUM> and are configured to project from an interior surface of a first wall of the sub-housing and into the air flow path. For example, each sensor <NUM> may be mounted on an inner face of the PCB. Each sensor <NUM> may project from the PCB <NUM> and through a respective aperture of the sub-housing <NUM> so as to project into the air flow path. Alternatively, the sensors <NUM> are configured to project through apertures located on a first wall of the upper housing <NUM> or of the lower housing <NUM> so as to project into the air flow path.

In one form, the first wall comprises the front wall of the sub-housing and the PCB <NUM> is located between the face plate <NUM> and front wall of the sub-housing <NUM>. In another form, the first wall comprises the front wall of the inner and/or outer walls <NUM>, <NUM> of the upper housing <NUM> and the PCB <NUM> is located between the face plate <NUM> and the first wall. In a further form, the first wall comprises the front wall of the inner and/or outer walls <NUM>, <NUM> of the lower housing <NUM> and the PCB <NUM> is located between the face plate <NUM> and the first wall.

According to the present invention, by Or placing two or more sensors <NUM> on an interior face of the PCB <NUM> so that the sensors <NUM> are aligned with apertures formed on a first wall of the sub-housing <NUM>, upper housing <NUM>, or lower housing <NUM>, it is possible to easily install the sensors <NUM> in one movement by pushing the PCB <NUM> against the exterior surface of the first wall so that the sensors <NUM> are pushed through the respective apertures in the sub-housing <NUM>, upper housing <NUM>, or lower housing <NUM>, to project from the interior surface of the first wall. In one form, soft seals are provided over the apertures in the sub-housing <NUM>. Each soft seal is configured to receive a sensor therein. Preferably, the soft seals are co-moulded to the sub-housing <NUM>, upper housing <NUM>, or lower housing <NUM>. In this arrangement, during assembly the sensors <NUM> may be pushed through the apertures in the sub-housing <NUM>, upper housing <NUM>, or lower housing <NUM>, and into the soft seals <NUM>, as shown in <FIG>. Comoulding the soft seals onto the housing <NUM>, <NUM>, <NUM> simplifies assembly of the breathing assistance apparatus <NUM>, as the step of placing seals individually onto the sensors or into the apertures is removed, and fewer individual parts are required during assembly.

The sensors <NUM> may be connected to a control system comprising a control unit, which is typically located on the PCB <NUM>. In one form the control unit may be a processor or microprocessor. The control unit is able to receive signals from the sensors and convert these signals into measurement data, such as air pressure data, air humidity data, and power output from the heating plate, for example. In some forms, the control system may be configured to control and vary the operation of various components of the apparatus to help ensure that particular parameters (such as air pressure, humidity, and power output for example) fall within desired ranges or meet desired thresholds or values. Typically, the desired ranges, thresholds or values are predetermined and are programmed into the control unit of the control system.

Preferably, one or more sensors <NUM> and the PCB <NUM> are located near the face plate <NUM>, such as behind the face plate, so that removal of the face plate <NUM> allows the sensors <NUM> to be easily accessed for servicing or replacement, if required.

Although the face plate <NUM> has been described as forming an outer surface/outer wall for both the upper <NUM> and lower <NUM> housing, in other configurations, the face plate <NUM> may form the outer surface/outer wall of just the upper housing <NUM> or just the lower housing <NUM>. In such a configuration, the housing that does not employ the face plate <NUM> as an outer surface/outer wall may instead comprise an outer wall substantially adjacent to each inner wall of that housing. In one form, the apparatus <NUM> may be configured so that the face plate <NUM> forms at least part of an outer surface/outer wall for the upper housing <NUM>, the lower housing <NUM>, and the base <NUM>.

Even though the construction of the apparatus <NUM> is such that liquid is less likely to enter the underside of the upper <NUM> and lower <NUM> housings, the lower housing <NUM> may comprise one or more drainage channels <NUM>. The drainage channels are configured to allow any water or other liquid within the housing <NUM> to drain away from the underside of the upper housing <NUM> to avoid the risk that the liquid could otherwise come into contact with the electronic components within the lower housing <NUM>. The lower housing <NUM> may comprise one or more outlets <NUM> through which liquid from the drainage channel(s) <NUM> may exit the apparatus <NUM>. In one form, one or more outlets <NUM> may be located in the rear wall of the apparatus <NUM>. In another form, one or more outlets <NUM> may be located on a side wall of the apparatus <NUM>. In one form, one or more outlets <NUM> may be located near one or both front corners of the apparatus <NUM>. For example, one or more drainage channels <NUM> may be located along one or both sides of the apparatus <NUM> and may terminate in outlets <NUM> provided at the front, side or rear of the apparatus. Preferably, a drainage channel <NUM> is provided along each side of the lower housing <NUM> and each channel <NUM> terminates in an outlet <NUM> provided at the respective side of the apparatus <NUM> and near a front or rear corner of the apparatus <NUM>. Preferably, the outlet(s) <NUM> is/are located at or near the join between the upper <NUM> and lower housing <NUM>.

The base <NUM> may comprise an exterior surface that is shaped to be similar to that of the lower housing <NUM>. In one form, the exterior surface of at least an upper portion of the base <NUM> is substantially the same shape and dimensions as a lower portion of the lower housing <NUM> so that when the base <NUM> and lower housing <NUM> are connected together, a substantially flush outer surface is provided across the two parts <NUM>, <NUM>. Preferably, the base comprises substantially opposing side walls 331a, 331c, and a rear wall 331b extending between the two side walls. A lower wall may be located may be connected to and located between the side walls and rear wall to form the floor of the base <NUM>, on which a PCB <NUM> and various electronic components may be supported. The wall(s) <NUM> of the base may be substantially short so as to form a lip surrounding at least a portion of the periphery of the base <NUM>. In one form, the base <NUM> also comprises a front wall that is located substantially opposite the rear wall and that extends between the side walls. In another form, a gap is provided at the front of the base and between the two side walls. The gap may be configured to receive at least a portion of a face plate <NUM> therein.

In one form, the control system may comprise a printed circuit board (PCB) <NUM>, for controlling various operations of the apparatus. The PCB <NUM> may be located between the underside of the lower housing <NUM> and the base <NUM>. Because the base <NUM> may be configured to house a PCB <NUM> and other electronic components, it is important that the electronics are kept as dry as possible. Therefore, the base <NUM> may comprise one or more drainage channels <NUM> to drain away liquid from the base <NUM> and to help prevent liquid from coming into contact with the sensitive electronic components, As shown in <FIG> and <FIG>, the drainage channel(s) <NUM> in the base <NUM> may connect with one or more outlets <NUM>, which may be located at the side of the apparatus <NUM>, the rear of the apparatus <NUM>, and/or the front of the apparatus. In one form, one or more drainage channels may be located along one or both sides of the apparatus <NUM> and may terminate in outlets <NUM> provided at the front, side, or rear of the apparatus. Preferably, a drainage channel is provided along each side of the base <NUM> and each channel terminates at an outlet provided at the respective side of the apparatus <NUM> and near a front or rear corner of the apparatus <NUM>. In one form, one or more drainage channels may each terminate at an outlet located near the front edge of the base <NUM>, such as between the base <NUM> and the face plate <NUM> for example.

Preferably, the PCB <NUM> rests on one or more compressible supports <NUM> within the base, as shown in <FIG>. The compressible supports may be of any suitable construction, such as rubber or silicone columns for example. The compressible support(s) <NUM> may help to protect the PCB <NUM> and its electronic components and connections from breaking under at least some impact forces.

To help prevent dislodgement of electronic connectors to the PCB <NUM>, the base <NUM> may comprise one or more guides <NUM> to hold the electrical connectors <NUM> in a desired position, as shown in <FIG>. In one form, the guide(s) <NUM> may comprise one or more arms located along an inside wall of the base <NUM>. The one or more guides <NUM> may be arranged to project toward one or more electrical connectors <NUM> and to press against the connectors <NUM> to ensure that the connectors <NUM> do not move from the desired position when the apparatus <NUM> is knocked or subjected to an impact force, for example.

In some forms, it may be preferable to include a safety mechanism within the breathing assistance apparatus to help ensure that the heating element of the apparatus does not overheat and fail or catch fire. In prior art breathing assistance apparatuses, a mechanical cut-off switch was used to disable power to the heating element if the cut-off switch was tripped, such as if the measured temperature of the heating element exceeds a first predetermined threshold. In one form, the apparatus of the invention may use the same prior art system.

In another form, the electronic control system of the apparatus may form a safety mechanism that protects against overheating by the heating element. In this form, the control system may be programmed using software configured to control the operation of the heating element. For example, the heating element may be configured to operate below a desired maximum operating temperature threshold. In one form, the desired maximum temperature threshold may be a temperature between approximately <NUM> and <NUM>, such as <NUM>. If the temperature of the heating element exceeds a predetermined temperature threshold, such as the maximum operating temperature or a temperature slightly higher than the desired maximum operating temperature, the control system may disable power to the heating element. In other words, the programmable control system may control the heating element temperature by modulating power to the heating element, such as by maintaining an electrical connection to provide power to the heating element and by disabling the electrical connection to disable power to the heating element. The control system may be configured to cause power modulation by using the control unit to control the operation of one or more components of the control system by sending electronic signals to one or more components of the system. One or more components of an electronic protection circuit (described in further detail below) may also be configured to provide feedback to the control unit via electronic signals. In this way, the control system may be configured to cause the heating element to substantially maintain (or at least not exceed) a predetermined temperature.

An electronic signal used in the control system may be any suitable form of signal, including the introduction of a signal where no signal was already present, a change to an existing signal, or a discontinuation (temporary or permanent) of an existing signal between the control unit and one or more components of the control system.

The apparatus may be configured in different ways to control the heating element temperature and to provide protection systems to prevent overheating of the heating element.

In one form, as shown in <FIG>, the control system may comprise the control unit <NUM> (as described above) and a first electronic protection system or circuit connected to the control unit <NUM>. The first electronic protection circuit may comprise: a first temperature sensor <NUM>; a first comparator circuit <NUM>; and a first switching member <NUM>. The first sensor <NUM> is configured to measure the temperature of the heating element <NUM> and provide first temperature sensor outputs to the first comparator circuit <NUM>. The first comparator circuit <NUM> is a circuit (such as an op-amp) within the first electronic protection circuit that is configured to compare the first temperature sensor output to a first predetermined temperature threshold T1 to determine whether the heating element <NUM> is too hot, and to maintain or disable power to the heating element <NUM> depending on the output from the first sensor <NUM> and the determination of the heating element temperature. If the heating element temperature sensed by the first temperature sensor <NUM> lies below a first predetermined threshold T1, the first comparator circuit <NUM> will not cause the first switching member <NUM> to disable power to the heating element <NUM>. Conversely, if the first comparator circuit determines that the first temperature sensor output exceeds the first predetermined threshold T1, the first comparator circuit <NUM> sends a signal <NUM>, such as a DISABLE signal, to the first switching member to disable power to the heating element.

In one form, the first comparator circuit <NUM> may be configured to provide feedback to the control unit <NUM> by signaling <NUM> to the control unit <NUM> when a DISABLE signal <NUM> has been sent to the first switching member <NUM>, or signaling <NUM> to the control unit <NUM> when no DISABLE signal <NUM> has been sent to the first switching member <NUM>.

Additionally or alternatively, the control unit <NUM> may be configured to cause the first switching member <NUM> to disable power to the heating element <NUM> when the heating element <NUM> exceeds a first predetermined programmed temperature threshold, which is programmed into the control unit using software. In this form, the first electronic protection circuit is configured to provide feedback to the control unit <NUM> via electronic signals <NUM>, <NUM>. For example, the first temperature sensor <NUM> may be configured to provide sensed temperature outputs as feedback signals <NUM> to the control unit <NUM>. The control unit <NUM> is programmed to receive the sensor output and determine if the heating element temperature is below the first programmed temperature threshold. If the control unit <NUM> determines that the sensed temperature exceeds the first programmed temperature threshold, the control unit <NUM> may send a signal <NUM> to the first switching member <NUM> to disable power to the heating element <NUM>. For example, when the sensed heating element temperature exceeds the first programmed temperature threshold, the control unit <NUM> may send an electronic DISABLE signal <NUM> to the first switching member <NUM> to cause the first switching member <NUM> to disable power to the heating element <NUM>. In this form, the first programmed predetermined temperature threshold may be different to, the same as, or similar to, the first predetermined threshold T1 of the first comparator circuit.

In one form, the first electronic protection circuit may comprise a logic gate <NUM> and signals <NUM>, <NUM> from the first comparator circuit <NUM> and the control unit <NUM> may be sent to the logic gate <NUM>. If both signals <NUM>, <NUM> indicate that the heating element is at a desired operating temperature, the logic gate may signal <NUM> to the first switching member <NUM> to maintain power to the heating element <NUM>. Conversely, if either signal <NUM>, <NUM> indicates that the heating element <NUM> is too hot, the logic gate <NUM> will signal <NUM> to the first switching member to disable power to the heating element <NUM>.

In this way, the control system also provides a secondary or back up protection mechanism to disable power to the heating element if the first electronic protection circuit does not cause the first switching member to disable power to the heating element.

In addition to the first electronic protection system or circuit, as shown in <FIG>, the control system may comprise the control unit (as described above) and a second electronic protection circuit connected to the control unit. In this form, as above, the control system may be configured to control the operation of the second electronic protection circuit by sending electronic signals to one or more components of the second electronic protection circuit. One or more components of the second electronic protection circuit may also be configured to provide feedback to the control unit via electronic signals. For example, the second electronic protection circuit may comprise: a second temperature sensor <NUM>; a second comparator circuit <NUM>; and a second switching member <NUM>. In this form, the second sensor <NUM> is configured to measure the temperature of the heating element <NUM> and provide a second temperature sensor output to the second comparator circuit <NUM>. The second comparator circuit <NUM> is a circuit (such as an op-amp) within the second electronic protection circuit that is configured to compare the second temperature sensor output to a second predetermined temperature threshold T2 to determine whether the heating element <NUM> is too hot, and to maintain or disable power to the heating element <NUM> depending on the output from the second sensor <NUM> and the determination of the heating element temperature. If the sensed heating element temperature lies below the second predetermined temperature threshold T2, the second comparator circuit <NUM> will not cause the second switching member <NUM> to disable power to the heating element <NUM>. Conversely, if the second comparator circuit <NUM> determines that the second temperature sensor output exceeds the second predetermined temperature threshold T2, the second comparator circuit <NUM> sends a signal <NUM>, such as a DISABLE signal, to the second switching member <NUM> to disable power to the heating element.

The second switching member <NUM> may comprise a moveable switch, such as a mechanical isolation switch, configured to move from a first, connecting position to a second, disconnecting position to provide a physical disconnection of power to the heating element <NUM> by physically breaking the electronic circuit to the heating element <NUM> if the sensed temperature of the heating element <NUM> is too high.

In one form, the second comparator circuit <NUM> may be configured to provide feedback to the control unit <NUM> by signaling <NUM> to the control unit <NUM> when a DISABLE signal <NUM> has been sent to the second switching member <NUM>, or signaling <NUM> to the control unit <NUM> when no DISABLE signal <NUM> has been sent to the second switching member <NUM>.

The control unit may also be configured to cause the second switching member to disable power to the heating element when the heating element exceeds a second predetermined programmed temperature threshold, which is programmed into the control unit using software. In this form, the second electronic protection circuit is configured to provide feedback to the control unit <NUM> via electronic signals <NUM>, <NUM>. For example, the second temperature sensor <NUM> may be configured to provide sensed temperature outputs as feedback signals <NUM> to the control unit. The control unit <NUM> is programmed to receive the sensor output and determine if the heating element temperature is below the second programmed temperature threshold. If the control unit <NUM> determines that the sensed temperature exceeds the second programmed temperature threshold, the control unit <NUM> may send a signal <NUM> to the second switching member <NUM> to disable power to the heating element <NUM>. For example, when the sensed heating element temperature exceeds the second programmed temperature threshold, the control unit <NUM> may send an electronic DISABLE signal <NUM> to the second switching member <NUM> to cause the second switching member <NUM> to disable power to the heating element <NUM>. In this form, the second predetermined software threshold may be different to, the same as, or similar to, the second predetermined threshold T2 of the second comparator circuit. The second predetermined threshold temperature T2 may be equal to or higher than the first predetermined threshold temperature T1.

In one form, the second electronic protection circuit may comprise a logic gate <NUM>. Signals <NUM>, <NUM> from the second comparator circuit <NUM> and the control unit <NUM> may be sent to the logic gate <NUM>. If both signals <NUM>, <NUM> indicate that the heating element <NUM> is at a desired operating temperature, the logic gate <NUM> may signal <NUM> to the second switching member <NUM> to maintain power to the heating element <NUM>. Conversely, if either signal <NUM>, <NUM> indicates that the heating element <NUM> is too hot, the logic gate <NUM> will signal <NUM> to the second switching member <NUM> to disable power to the heating element <NUM>.

In this arrangement, the control system acts as a secondary or back up protection mechanism configured to disable power to the heating element <NUM> if the second electronic protection circuit fails to cause the second switching member <NUM> to disable power to the heating element <NUM>.

In another form, the control unit <NUM> may be configured to disable power to the heating element <NUM> via both the first and second switching members <NUM>, <NUM> if the sensed temperature of the heating element <NUM> exceeds a predetermined temperature threshold (the sensed temperature being determined from the first <NUM> and/or second <NUM> sensor). For example, when the sensed temperature of the heating element <NUM>, as measured by the first <NUM> and/or second sensor <NUM>, exceeds a predetermined threshold, the control unit <NUM> may signal to both the first switching member <NUM> and to the second switching member <NUM> to disable power to the heating element <NUM>.

In one form, at least the first switching member <NUM> and optionally the second switching member <NUM> may be reset when the first electronic protection circuit identifies from the first sensor outputs that the heating element temperature has dropped below T1.

In one form, the second electronic protection circuit may only be resettable by power cycling the apparatus. For example, if the second electronic protection circuit is reset, the second switching member, which is preferably a mechanical isolation switch, may move from a disconnecting position to a connecting position to reinstate power to the heating element.

In a preferred form, the second switching member, which may be a mechanical isolation switch, is in a disconnecting position when the breathing assistance apparatus is not providing therapy, and is only moved to a connecting position by the control unit when the breathing assistance apparatus is providing therapy. Having the mechanical isolation switch in a disconnecting position prevents damage to the electronics that may otherwise be caused by any power surges that occur when the device is not providing therapy.

The mechanical isolation switch may be any suitable form of switch, such as an electronically controlled switch configured to provide a mechanical connection and disconnection of power to the heating element by moving from a first position to a second position. For example, the mechanical isolation switch may be a relay.

The electronic switching member configured to electronically disconnect power to the heating element may also be any suitable form of electronic switch to connect and disconnect power to the heating element, such as a triac, metal-oxide-semiconductor field-effect transistor (MOSFET), or insulated-gate bipolar transistor (IGBT) for example.

In one form, the control system of the apparatus <NUM> may comprise only the first electronic protection circuit or only the second electronic protection circuit, as described above, or the control system may comprise both the first and second electronic protection circuits described above, as shown in <FIG>.

In one form, the programmable control unit may be configured to monitor outputs (the sensed temperature readings) of the first and second temperature sensors and to independently calculate the sensed temperature of the heating element based on those outputs. In one form, this calculation is made by averaging the temperature outputs from the first and second temperature sensors. The resulting calculation is referred to herein as the control unit sensed temperature. In another form, the control unit may calculate the control unit sensed temperature by utilizing peak temperature sensing or other suitable signal processing techniques.

In one form, when the control unit sensed temperature exceeds a predetermined programmed temperature threshold, the control unit may cause the first and/or second switching members of the first and second electronic protection circuits respectively to disable power to the heating element. The predetermined programmed temperature threshold may be below, equal to or higher than the first predetermined temperature threshold T1, or below, equal to or higher than the second predetermined temperature threshold T2.

In one form, where the control system comprises only a first electronic protection circuit comprising only a first switching member, the control unit may be configured to trigger the first switching member to disable power to the heating element if the control unit sensed temperature remains at or above a predetermined threshold temperature for a predetermined period of time. Where the control system comprises first and second electronic protection circuits with first and second switching members, the control unit may be programmed to trigger one or both switching members to disable power to the heating element if the control unit sensed temperature remains at or above a predetermined threshold temperature for a predetermined period of time. For example, the control unit may trigger the mechanical isolation switch to disable power to the heating element.

In one form, the control unit may be programmed to identify the difference in outputs between the first and second temperature sensors and to cause one or both switching members to disable power to the heating element when the control system identifies that the outputs of the first and second sensors differ by a predetermined programmed threshold. If the control unit detects a difference in the outputs of the first and second temperature sensors, then it is possible that at least one of the temperature sensors has failed, and that either one or both of the first and second electronic protection circuits may not reliably disable power to the heater plate.

In one form, as shown in <FIG>, the apparatus <NUM> may be configured to use air flow to help cool the electronics in the base <NUM>. For example, a venturi channel <NUM> may be provided between a bottom surface of the floor <NUM> of the sub-housing <NUM> and a top surface of the floor <NUM> of the lower housing <NUM>. The channel may provide an inlet flow path for air flowing from an inlet toward the blower. The air inlet may be located on a real wall, side wall or front wall of the apparatus <NUM>. Where the floor <NUM> of the lower housing is substantially thin, the flow of air along the channel <NUM> may cool the area beneath the floor <NUM>. In other words, by configuring the apparatus to direct air flow through the channel <NUM>, it may be possible to help cool electronic components held beneath the floor of the lower housing.

The base <NUM> may be configured to provide a substantially stable platform on which the upper <NUM> and lower <NUM> housings may be supported. It may be particularly important for the apparatus <NUM> to remain stable, such as when a user is loading or unloading the humidification chamber, to help prevent water leaks and protect the electronics within the apparatus <NUM>. To help the stability of the apparatus <NUM>, the apparatus <NUM> may comprise at least two feet <NUM> located on opposing sides of the apparatus <NUM> and configured to provide the apparatus <NUM> with a stable base. For example, the feet <NUM> may be substantially elongate and may extend along at least a portion of opposing sides of the bottom surface of the apparatus <NUM>. Preferably, bottom surfaces of the feet <NUM> are at least partially tacky. For example, the bottom surfaces of the feet <NUM> may comprise rubber to increase friction between the feet <NUM> and a supporting surface on which the apparatus <NUM> is located during use.

In one form, the apparatus <NUM> comprises three feet <NUM> to provide increased stability. The three feet <NUM> may be substantially evenly or unevenly spaced on the bottom surface of the apparatus <NUM>. In one form, as shown in <FIG>, the apparatus <NUM> may comprise an elongated foot 500a projecting from the bottom surface of the apparatus and extending in a direction from one side of the apparatus to the other. The apparatus may also comprise two smaller feet spaced apart from the elongate foot. For example, one foot (such as a small round or otherwise shaped foot) may be located at or near each front corner of the apparatus and a third elongate foot may be located near the rear of the apparatus and be oriented to extend from one side of the apparatus to the other, as shown in <FIG>. Spaces provided between the feet <NUM> allow for air to flow freely beneath the apparatus <NUM>, which may help to cool the base <NUM> of the apparatus where the electronics may be held. In one form, the feet <NUM> project from the bottom surface of the base <NUM> of the apparatus <NUM>.

To attach the parts of the apparatus <NUM> together, the upper and lower housings <NUM>, <NUM> may be formed separately and may then be connected together in any suitable configuration to form the body <NUM> of the apparatus <NUM>. Preferably, the upper housing <NUM>, including the inner and outer walls <NUM>, <NUM> and lower wall <NUM>, is formed as a single part. Additionally or alternatively, the lower housing <NUM>, including the inner and outer walls <NUM>, <NUM> and lower wall <NUM>, is formed as a single part. The upper housing <NUM> is located above the lower housing <NUM> and is attached to the lower housing <NUM>, which may in turn be attached to the base <NUM> to form the body <NUM> of the apparatus <NUM>. A sub-housing <NUM> may be located within the apparatus and between the upper housing <NUM> and lower housing <NUM>.

In one form, the upper housing <NUM>, lower housing <NUM>, and base <NUM> are connected together by fasteners that engage with each of these three parts <NUM>, <NUM>, and <NUM> of the apparatus <NUM>. For example, fasteners in the form of screws, bolts, or the like may extend through substantially aligned attachment apertures in the upper housing <NUM>, lower housing <NUM> and base <NUM> to attach all three parts together. The aligned attachment apertures may be placed at any suitable location. In one form, the body <NUM> of the apparatus <NUM> comprises four outer corners and the aligned attachment apertures are located near the outer corners. A screw or bolt or other suitable fastener may be inserted into the aligned attachment apertures to attach the upper housing <NUM>, lower housing <NUM>, and base <NUM> together. In one form, the sub-housing <NUM> may also comprise one or more attachment apertures that align with the attachment apertures of the upper and lower housings and base so that fasteners can be used to attach all of the components <NUM>, <NUM>, <NUM>, <NUM> together.

In this configuration, a gap <NUM> may be formed between a lower peripheral edge of the outer wall of the upper housing <NUM> and an upper edge of the lower housing <NUM>. Sometimes, the gap <NUM> may be of uneven width along its length as the gap extends around the body <NUM> of the apparatus <NUM>. The uneven width of the gap <NUM> may be aesthetically unattractive. Therefore, to provide a gap <NUM> having a substantially constant width around the body <NUM> of the apparatus <NUM>, the body <NUM> of the apparatus may comprise at least two spacers, which may be in the form of protrusions <NUM>, or the like, of substantially equal height that extend into the gap <NUM> to space the upper housing <NUM> and lower housing <NUM> at an equal distance apart, as shown in <FIG>. In one form, the spacers <NUM> may be located on an upper edge of the lower housing <NUM>. In another form, the spacers <NUM> may be located on a lower edge of the upper housing <NUM>, particularly on the lower edge of an outer wall of the upper housing <NUM>. The spacers <NUM> may be of any suitable height, such as between <NUM> to <NUM> for example. In a preferred form, the spacers <NUM> are <NUM> high.

In one form, as shown in <FIG>, the breathing assistance apparatus <NUM> may be configured to comprise an outlet seal <NUM> that is configured to help create a sterile environment at the connection between an air outlet <NUM> of the apparatus and the breathing tube <NUM>. In this configuration, it may be easier to refurbish the apparatus <NUM> between uses by different patients.

The outlet seal <NUM> is configured to be at least partially located within the air outlet <NUM> of the apparatus <NUM>. An air flow path is provided between the body <NUM> and connection port <NUM> so that air may flow through the outlet seal in the air outlet <NUM> and into the breathing tube <NUM>.

The air outlet <NUM> and outlet seal <NUM> may be shaped to substantially complement each other so that outer surfaces of the outlet seal <NUM> may substantially seal against inner surfaces of the air outlet <NUM> when the outlet seal <NUM> is placed within the air outlet <NUM>.

In one form, the air outlet <NUM> is located within the rear wall structure of the apparatus. However, in other forms, the air outlet may be located in a side wall of front wall of the apparatus. A first portion of the air outlet <NUM> may comprise a non-circular interior surface to help prevent the outlet seal from rotating within the air outlet. In one form, the non-circular interior surface may be a quadrilateral surface, such as a rectangular surface, as shown in <FIG>. A second portion of the air outlet <NUM> may comprise a substantially circular interior surface configured to receive an end of a breathing tube <NUM> having a substantially circular peripheral surface. The first portion of the air outlet is typically open to the interior wall of the apparatus <NUM> and the second portion of the air outlet is typically open to the exterior wall of the apparatus <NUM>.

In one form, the outlet seal <NUM> comprises a body <NUM> and a connection port <NUM> that projects from the body <NUM>. The connection port <NUM> of the outlet seal <NUM> may comprise a substantially circular interior surface to envelop and substantially seal against an end of a breathing tube <NUM> having a substantially circular peripheral surface. Optionally, the exterior surface of the connection port <NUM> may also be substantially circular and may be configured to seal against a substantially circular interior surface of the air outlet <NUM>.

In one form, the body <NUM> of the outlet seal <NUM> may comprise a non-circular exterior surface configured to substantially seal against or engage with the first portion of the air outlet. For example, where the first portion of the air outlet <NUM> comprises a rectangular interior surface, the exterior surface of the outlet seal body <NUM> may also be rectangular and may be configured to fit snugly within the first portion of the air outlet <NUM>. In this configuration, it is not possible for the outlet seal <NUM> to rotate within the air outlet <NUM>.

The outlet seal <NUM> may be placed within the first portion of the air outlet <NUM>, such as by pushing the connection port <NUM> and at least part of the body <NUM> of the outlet seal into the first portion of the air outlet <NUM>.

Preferably, the outlet seal <NUM> is configured so that the inner surface of the connection port <NUM> has a diameter substantially the same as that of the inner surface of the second portion of the air outlet <NUM>. In this arrangement, an end of a breathing tube <NUM> (or an adapter <NUM> that connects to a breathing tube) may be pushed, from the exterior of the apparatus <NUM>, into the second portion of the air outlet <NUM> and into the connection port <NUM> of the outlet seal.

In one form, a stop, such as a flange or one or more projections, may be located between the interior surface of the connection port <NUM> and the body <NUM> of the outlet seal. The stop may be configured to prevent the end of the breathing tube <NUM> or adapter <NUM> from extending into the body <NUM> of the outlet seal.

In one form, the outlet seal <NUM> and air outlet <NUM> may be configured so that substantially the whole of the outlet seal <NUM> is located within the air outlet <NUM>. In another form, the body <NUM> of the outlet seal may comprise a depth control member that extends from a side of the outlet seal <NUM> and that is configured to prevent the whole of the outlet seal <NUM> from being pushed into the air outlet <NUM>. For example, the depth control member may be a flange or other form of projection that extends from a side of the outlet seal body <NUM> and that abuts the interior surface of the wall within which the air outlet is located to prevent the outlet seal from being pushed further into the air outlet.

In one form, the outlet seal comprises a gripping region to enable a user to easily grip the seal and extract the seal from the air outlet. The gripping region is typically located on the body of the outlet seal. In one form, the gripping region comprises a tab that projects from the body and that is configured to abut the interior surface of the wall within which the air outlet and outlet seal are located. In this arrangement, the tab <NUM> is easily accessible when the seal is placed within the air outlet <NUM>. To extract the outlet seal <NUM> from the air outlet <NUM>, a user simply needs to pull on the tab <NUM> with suitable force. The tab may be used as both a gripping region and a depth control member.

A significant advantage of the apparatus <NUM> is that it may be manufactured from the top down. For example, the apparatus <NUM> may begin to be constructed by placing the lid <NUM> upside down and then locating the upper housing <NUM> on the lid <NUM>. The lower housing <NUM> can then be connected to the upper housing <NUM> and then the base <NUM> may be connected to the lower housing <NUM>. The face plate <NUM> may then be attached to the assembled unit. By building the apparatus <NUM> from the top down, the apparatus <NUM> may be constructed almost entirely from one position. It is therefore possible to reduce handling and manufacturing time.

The upper housing <NUM> of the apparatus may be manufactured as a single part by injection moulding, with the gates in two opposite corners on the top edge or upper surface <NUM> of the housing, from which the plastic can reach both the inner and outer walls without overly stressing the moulding tools. As a result of this form of manufacture, it is possible to provide the upper housing with an outer wall structure in which the inner and outer walls are integrally formed to avoid a join between the walls. It is desirable to avoid placing a join between the inner and outer walls because water and other liquids may otherwise enter into the join and seep between the inner and outer walls to access electronic components within the apparatus. The lower housing may also be injection moulded in the same manner.

Claim 1:
A breathing assistance apparatus for the delivery of breathing gas to a user, the apparatus comprising:
a body (<NUM>) and a lid (<NUM>), the body comprising at least one housing (<NUM>), the at least one housing comprising three inner walls (131a, 131b, 131c) and three outer walls (132a, 132b, 132c), wherein each of the three outer walls is substantially adjacent to and spaced apart from a respective one of the three inner walls;
an upper surface (<NUM>) spanning between upper edges of the three outer walls and the three inner walls, wherein the three outer walls, the three inner walls, and the upper surface are integrally formed,
wherein the three inner walls form an enclosure for a humidification chamber,
wherein the lid covers the enclosure, and
wherein the housing further comprises a fourth inner wall (131d) and a tinted face plate (<NUM>), the tinted face plate located substantially adjacent to and spaced apart from the fourth inner wall to form a fourth outer wall of the at least one housing; and
a printed circuit board, PCB, (<NUM>) located between the tinted face plate (<NUM>) and the fourth inner wall, and wherein two or more sensors (<NUM>) are located on a first face of the PCB and aligned with apertures formed on a first wall of a sub-housing (<NUM>), an upper housing (<NUM>), or a lower housing (<NUM>) and configured to project into an air flow path; and
an LED screen located behind and visible through the tinted face place (<NUM>).