GB2508589A

GB2508589A - Hair dryer nozzle having a vent

Info

Publication number: GB2508589A
Application number: GB201221672A
Authority: GB
Inventors: Daniel Brady; Steve Sayers; Christopher John Jones; Simon Lewis Bilton
Original assignee: Jemella Ltd
Current assignee: Jemella Ltd
Priority date: 2012-12-03
Filing date: 2012-12-03
Publication date: 2014-06-11
Also published as: WO2014087136A1

Abstract

A hair dryer nozzle 10 comprises an air inlet 14, an air outlet 12 and one or more venting apertures 16. A valve mechanism, such as rotary valve mechanism 20, is moveable between a closed position, in which apertures 16 are covered, and an open position, to open the venting apertures 16, when the temperature within the housing exceeds a threshold value. The actuator for such a valve mechanism 20 may be one configured to change shape in response to a temperature change, such as a bimetallic coil. Alternative nozzles are also described (30, fig. 3a, 70, fig 7a, 80, fig8a) which have vents opened in response to an increase in pressure within the housing rather than temperature, e.g. if the outlet of the nozzle is restricted, air may then escape through the one or more venting apertures to prevent heat build-up within the nozzle or hair dryer.

Description

Hair Styling Apparatus

FIELD OF THE INVENTION

The invention relates to hair dryers, in particular to nozzles for hair dryers.

BACKGROUND TO THE INVENTION

A typical hand-held hair dryer comprises a hand-held housing with an air inlet, an air outlet, and a motor in between to draw air in from the air inlet and drive air out from the air outlet. A heating element is located in the air flow between the air inlet and the air outlet, typically after the motor in the air flow. A nozzle may be attached to such a hair dryer to provide a concentrated flow of air.

Safety is an important aspect in the design of hair dryers as the presence of a heater element can be potentially dangerous without appropriate venting and continued dispersernent of the heated air In the event of a blockage or severe restriction at the outlet there is a risk that parts of the hair dryer may overheat and that the heater element may burn out. The increase in temperature may also be potentially hazardous to the user.

Conventionally, thermal cut outs are used in hair dryers to address this problem, however they may cause the temperature to oscillate between 100°C and 250CC before a control loop shuts off the heater element. In the event of a total blockage in the outlet, there is a risk that the temperature may increase beyond 250°C before a thermal cut out activates. If a blockage is removed before the thermal cut out has activated, a stream of high temperature air, perhaps up to 300t may be emitted which risks burning a user and/or stylist.

US 4,430,808 shows one example of a hair dryer with a hollow cylindrical hair winding attachment having air blowing holes disposed along its length. EP 0 284 690 shows a hair dryer with exhaust holes arranged in an opposite direction to the out blowing air flow, and optional pressure flaps may cover the exhaust holes.

The present applicant has recognised the need to provide alternative solutions which prevent overheating and which are more readily adapted to modern day hair dryers.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a hair dryer nozzle comprising: a housing having an air inlet and an air outlet; a venting aperture in the housing for venting air from the housing; and a valve mechanism which is moveable relative to said housing between a closed position to close said venting aperture and an open position to open said venting aperture wherein said valve mechanism is configured to move from said closed position to said open position when a temperature within said housing exceeds a threshold value.

In use, the hair dryer nozzle according to the first aspect may be attached to a hair dryer such that hot air produced from the hair dryer flows through a primary air flow channel from the nozzle inlet and out through the nozzle outlet. Any blockage of the nozzle outlet may lead to an increase in temperature within the nozzle housing. The inclusion of a venting aperture provides a secondary air flow channel for heated air to escape from the housing when the temperature in the housing exceeds a threshold value. In normal use, the secondary air flow channel is closed. However, the valve mechanism reacts to an increase in temperature and moves from a closed position to an open position to open the secondary air flow channel in order to alleviate the temperature increase and avoid overheating within the nozzle housing. Furthermore, this may also prevent overheating in the hair dryer to which a nozzle may be coupled when in use.

The valve mechanism may be located within the nozzle housing to minimise the risk of hair being caught in the mechanism during styling. Alternatively, valve mechanism may be located on an outer surface of the nozzle housing. In this arrangement, the nozzle housing may further comprise a cover over the valve mechanism. Thus both arrangements reduce the risk of the valve mechanism becoming blocked by hair.

The threshold value may be between 150 and 200°C, such as 160°C.

The nozzle housing may comprise a plurality of venting apertures. In this way, a plurality of secondary air flow channels may be provided to vent air. The area of the venting aperture(s) may be equivalent to at least 70% of the area of nozzle outlet.

The valve mechanism may rotate relative to the housing such that the valve mechanism moves from the closed position to the open position to open the or each venting aperture and allow air to be vented from the housing. In embodiments where the valve mechanism is located within the nozzle housing, the shape of the valve mechanism may be configured to match the shape of the nozzle housing. In this way, any disruption of air flow through the primary air flow channel in normal use may be minimised. For example, both the nozzle housing and the valve mechanism may be generally cylindrical which also facilitates rotation. The nozzle housing may comprise an axle to which the valve mechanism is attached with rotation of the axle causing rotation of the valve mechanism. The axle may be generally aligned with a central axis of the nozzle housing. The valve mechanism may thus rotate axially, i.e. relative to a central axis of the housing. The valve mechanism may be concentrically mounted within the nozzle housing which may also facilitate rotation.

The valve mechanism may comprise a valve aperture corresponding to the or each venting aperture. Thus in embodiments where there is a plurality of venting apertures, there is also a plurality of valve apertures. In the open position the or each venting aperture and corresponding valve aperture may be at least partially aligned and may be fully aligned. In the closed position there is preferably no overlap of the or each venting aperture and the corresponding valve aperture.

The valve mechanism may comprise a hub, one or more spokes extending radially from the hub, and a rim coupled to the one or more spokes. In such an embodiment, the or each valve aperture may be located in the rim. In this way, the valve mechanism may take on the form of a cylindrical wheel-like structure with one or more valve apertures in the rim. The rim may be shaped to match an interior surface of the nozzle housing. By using a cylindrical structure, any disruption to the primary air flow channel from the nozzle inlet to the nozzle outlet is minimised.

In embodiments of the nozzle, the valve mechanism may comprise an actuator which is configured to change shape in response to a temperature increase and to cause said rotation when said temperature rises above the threshold value. The actuator may be made from a shape memory material, for example a bimetallic coil. The actuator may be coupled between the housing and the valve mechanism such that the change in shape induces the movement of the valve mechanism relative to the housing. For example, in the embodiment comprising an axle, the actuator may be wound around the axle so that a change in shape of the actuator causes the axle to rotate.

In some embodiments the degree of change in shape may be proportional to the change in temperature such that the valve mechanism can be controlled to gradually move between said closed position and said open position. In other words, the valve mechanism may also be moveable to an intermediate position in which the or each venting aperture is partially open. For example, in the embodiments comprising a valve aperture, the valve mechanism may be configured to rotate to a partially open position in which the or each valve aperture is only partially aligned with the corresponding venting aperture. The rotation to a partially open position may occur when the temperature exceeds a first threshold value and rotation to a fully open position may occur when the temperature exceeds a second higher threshold value.

In some embodiments, the valve mechanism may alternatively be arranged to deflect (i.e. displace mechanically) relative to the housing. This may then allow heated air to escape from the venting aperture with the valve mechanism moved to an open position as a result of the deflection. In this embodiment, the valve mechanism may comprise a cover corresponding to each venting aperture. The or each cover closes the corresponding venting aperture in the closed position and deflects to open the venting aperture in the open position.

The cover may comprise a shape memory material which is configured to change shape responsive to changes in temperature. In normal use, i.e. below the threshold value, the cover seals the corresponding venting aperture. As the temperature increases, the shape memory material changes shape to open the venting aperture. As the temperature reduces, the shape memory material may then return to its original shape such that the valve mechanism moves to the closed position and covers the venting aperture. In embodiments, the shape memory material may comprise a bimetallic strip.

In some embodiments the degree of change in shape may be proportional to the change in temperature such that the valve mechanism can be controlled to gradually move between said closed position and said open position. For example, the cover may be configured to deflect to a partially open position in which the or each valve aperture is only partially opened. The deflection to a partially open position may occur when the temperature exceeds a first threshold value and deflection to a fully open position may occur when the temperature exceeds a second higher threshold value.

The air inlet may be substantially circular such that it may be coupled to a correspondingly shaped outlet on a hair dryer. The air outlet may be substantially rectangular in order to provide a focused stream of heated air that may be used for styling.

The valve mechanism may comprise a thermistor to sense the temperature and a control circuit which is coupled to the thermistor which drives rotation of the valve mechanism when the thermistor detects that the temperature has exceeded the threshold value.

In a further variant, the valve mechanism may be moveable relative to the housing by coupling a magnet which loses its magnetic properties when heated above the threshold value to one of the valve mechanism and the housing and coupling a metallic element to the other of the valve mechanism and the housing. By coupling the magnetic material to one of the nozzle housing or valve mechanism and a metallic element to the other, the valve mechanism is locked by magnetic forces in the closed position but may rotate or deflect as the heated air flow exceeds the threshold temperature and the magnetic forces are removed. One or more magnets may be used, as well as one or more metallic elements.

According to a second aspect of the invention there is provided a method of controlling temperature within a hair dryer nozzle, the nozzle comprising a housing having an air inlet and an air outlet; a venting aperture in the housing for venting air from the housing; and a valve mechanism; the method comprising moving the valve mechanism relative to the housing between a closed position to close the venting aperture and an open position to open the venting aperture wherein movement from the closed position to the open position is responsive to an increase in temperature within the housing above a threshold value.

According to another aspect of the invention there is provided a hair dryer nozzle comprising a housing having an air inlet, an air outlet and an air flow channel between the air inlet and air outlet; wherein the housing is configured at the outlet to allow air to vent at an angle relative to the air flow channel when flow through the air outlet parallel to the air flow channel is restricted. For example, air flow in a direction generally parallel to the air flow channel may be restricted when the nozzle outlet is held against a volume of hair or placed on a surface.

The housing may be configured by comprising at least one projection which extends beyond the air outlet. The at least one projection spaces the nozzle away from a surface or volume of hair against which it is placed. There may be a plurality of projections which may define a plurality of channels therebetween. The channels may be at an angle (perhaps right angles) to the air flow channel.

At least one edge of the housing at the outlet end may comprise a recess or cutaway section allowing air to vent at an angle relative to the air flow channel. The recess may be curved or other shape. The at least one edge may comprise a plurality of recesses.

The plurality of recesses may be equally sized and/or equally spaced along one or more edges of the housing at the outlet end.

This aspect of the invention may be combined with the first aspect of the invention.

According to another aspect of the invention, there is provided a hair dryer nozzle comprising a housing having an air inlet, an air outlet and an air flow channel between the air inlet and the air outlet; and a choke within the air flow channel; wherein the choke is moveable relative to the housing between a first position in which the air flow channel has a first throughput and a second position in which the air flow channel has a second, reduced throughput. Thus, the choke is moveable within the air flow channel to change the mass flow rate of air through the air flow channel and out through the air outlet.

In the first position the choke may be adjacent the air outlet and may further project from the air outlet. In the second position, the choke may be wholly within the air flow channel. It will be appreciated that moving the choke further into the channel will reduce the air flow within the air flow channel thus reducing the throughput.

The choke and the air flow channel may be further shaped to increase the change in throughput between the first and second positions. The nozzle housing may comprise a neck portion between the air inlet and air outlet having a smaller cross-sectional area than the air outlet. The neck portion thus may form a choke point. In second position the choke is preferably adjacent the neck portion to reduce air flow through the channel. The choke may have a cross-section which is generally aerofoil shaped or at least is wider towards the inlet. The choke may be arranged with the narrower more pointed end of the choke at or projecting from the outlet.

The nozzle may comprise biasing means arranged to bias the choke to the first position. The biasing means may further comprise a spring. A temperature indicator may be coupled to the nozzle housing or choke.

According to another aspect of the invention, there is provided a method of providing heat build-up in a hair dryer nozzle, the nozzle comprising: housing having an air inlet, an air outlet and an air flow channel between the air inlet and air outlet; and a choke within the airflow channel; the method comprising: restricting air flow through the air flow channel by moving a choke relative to the nozzle housing from a first position in which the air flow channel has a first throughput to a second position in which the air flow channel has a second reduced throughput.

According to another aspect of the invention, there is provided a hair dryer nozzle comprising a housing having an air inlet and an air outlet; and a temperature indicator coupled to the housing to indicate a change in temperature.

This aspect of the invention may be combined with the other aspects of the invention.

The temperature indicator may comprise a thermochromic ink. Alternatively, the nozzle housing may comprise a thermochromic polymer or additive to provide the temperature indicator.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention and to show how it may be carried into effect, reference shall now be made, by way of example only, to the accompanying drawings in which: Figure la shows a 3D projection of a first hair dryer nozzle with rotary temperature sensitive venting valve in a closed position; Figure lb shows a cut away of the nozzle of Figure 1 a; Figure 2a shows a 3D projection of the nozzle of Figure la with the valve in an open position; Figure 2b shows a cut away of the nozzle of Figure 2a; Figure 3a shows a 3D projection of a second hair dryer nozzle with a closed temperature sensitive vent; Figure 3b shows the nozzle of Figure 3awith an open temperature sensitive vent; Figure 4 shows the nozzle of Figures 3a and 3b coupled to a hair dryer; Figure 5a shows a 3D projection of a nozzle with pressure sensitive venting; Figure Sb shows a cross section of the nozzle of Figure 5a; Figure 6a show a 3D projection of a further nozzle with pressure sensitive venting; Figure Gb shows a cross section of the nozzle of Figure Ga; Figure 7a shows a 3D projection of a third nozzle with pressure sensitive venting, with a pressure sensitive valve in the closed position; Figure 7b shows a further 3D projection of the nozzle of Figure 7a with the valve in the open position; Figure 7c shows a cross section of the nozzle of Figures 7a and 7b; Figure 8a shows a 3D projection of a fourth nozzle with pressure sensitive venting, with a pressure sensitive valve in the closed position; Figure 8b shows the nozzle of Figure Ba with the valve in the open position; Figure 9 shows a nozzle arrangement to minimise a reduction in air flow; Figure 10 shows a second nozzle arranged to minimise a reduction in air flow; Figure 11 shows a third nozzle arranged to minimise a reduction in air flow; Figures 1 2a-1 2d show a nozzle with a moveable choke; and Figures 13a-13b show mechanisms for providing temperature sensitive feedback to a user.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Generally speaking, air flow through nozzle outlets may become restricted if a stylist pushes the nozzle against hair which is being dried. Furthermore, when the hair dryer and coupled nozzle are set down but left running, there is a risk the nozzle may be placed against a surface which restricts the air flow. Such restriction of the air flow through the nozzle and hence through the hair dryer may lead to a rise in air temperature. This may be dangerous and the user and stylist may also damage the nozzle and attached hair dryer.

It is important that solutions avoid the risk of hair becoming tangled in any overheat prevention mechanism. Whilst being frustrating to a user, there is also a risk that the nozzle could fail to operate correctly.

Three approaches to preventing overheating are described herein that provide mechanisms for maintaining air flow, i.e. preventing blockages and maintaining an air flow through the nozzle and hence through the hair dryer. The first is a temperature sensitive venting mechanism, the second a pressure sensitive venting mechanism, and the third is a mechanism to prevent a reduction in -air flow.

In the described embodiments, experimental analysis suggests that in order to maintain a temperature of around 180°C the outlet flow from a nozzle should preferably be restricted by no more than 20-30%. To satisfy this condition in the event that the nozzle outlet is fully blocked, it may therefore be preferable in some embodiments to provide vents having an outlet area which is equivalent to 70-80% of the nozzle outlet area.

Figures la, lb, 2a and 2b show a first hair dryer nozzle 10 with a rotary temperature sensitive venting valve. Figure la shows a 3D projection of the first hair dryer nozzle with the rotary temperature sensitive venting valve mechanism 20 in a closed position.

Further details are shown in the cut away in Figure lb. Figure 2a shows a further 3D projection of the nozzle 10 with the valve mechanism 20 in an open position. Figure 2b shows a cut away of the nozzle 10 of Figure 2a with the valve mechanism 20 in the open position.

Referring to Figure la, the nozzle 10 has a housing 13 with a nozzle inlet 14 and a nozzle outlet 12. The nozzle inlet 14 is couplable to a hair dryer air outlet (not shown) which drives air through the nozzle. There is thus a primary air flow channel between the nozzle inlet 14 and nozzle outlet 12. In this embodiment, and by way of illustrative example only, the nozzle is arranged to have a substantially circular inlet 14 and a substantially rectangular outlet 12. The housing 13 thus comprises a generally cylindrical section having the circular inlet and a shaped section in which the shape of the housing is gradually transformed from a circular cross-section to a rectangular cross-section. The curvature of the shaped section is such that the air flow through the primary air flow channel is not restricted by the changing shape.

The nozzle 10 has one or more venting apertures 16 spaced around and extending through the sides of the nozzle housing 13. In the embodiment shown in Figures la to 2b the nozzle has four venting apertures which are equidistantly spaced around a circumference which approximately half-way along the cylindrical section of the housing. Located within the nozzle housing 13 is a rotary valve mechanism 20 which is moveable between a closed position in which the venting apertures are closed and an open position in which the venting apertures are open. When the venting apertures are closed, air flows through the primary air flow channel from the air inlet to the air outlet. When the venting apertures are open, the venting apertures provide a secondary air flow channel through which air can vent from the housing.

The nozzle housing 13 is provided with an axle 15 arranged to support the rotary valve mechanism 20 to allow rotation of the valve mechanism 20 relative to the nozzle housing. The rotary valve mechanism 20 is shaped to match the internal shape of the housing. Thus, in this embodiment, the rotary valve mechanism 20 is generally cylindrical to fit snugly within the cylindrical section of the housing. The rotary valve mechanism 20 comprises a central hub 17, with one or more spokes radiating from the hub 17 to hold an outer rim. The outer rim of the valve mechanism comprises one or more valve apertures. Typically (although not essential) the number of valve apertures in the rotating valve mechanism corresponds to the number of venting apertures on the nozzle housing. The shape of the valve apertures may also correspond to the shape of the venting apertures as shown in the present embodiment.

The valve mechanism further comprises a shape memory material, here a bimetallic coil 22 which is wound around the axle 15 of the nozzle housing. One end of the bimetallic coil 22 is secured to the hub 17 by a retaining clip 23 and the other end is secured through slot 25 to the end of axle 15.

The valve apertures are arranged such that when the valve mechanism is in the closed position as shown in Figures la and ib, the valve apertures 18 do not overlap with the corresponding venting apertures on the nozzle housing. In other words, the venting apertures are blocked by the rim of the valve mechanism. Accordingly, the heated air flow entering the nozzle through the nozzle inlet 14 passes out the nozzle outlet 12 only. In the illustrative embodiment shown in Figures 2a and 2b, when the valve mechanism is rotated to the open position, the valve apertures align with the venting apertures to open the venting apertures. This provides multiple paths for heated air to escape and thereby avoid overheating.

It will be appreciated, that a similar effect may be provided by a valve mechanism comprising covers which have a similar shape to the venting aperture. The covers may be supported on spokes radiating from a central hub as with the rim of the present embodiment. The covers may be rotatable from a closed position in which they sit in front of and block the venting apertures to an open position in which they are spaced apart from the venting apertures.

In either arrangement, the rotation may be such as to only partially open the venting apertures, for example, the valve aperture may only partially align with the venting apertures. The more the venting apertures are opened, the greater the air flow possible through the venting apertures if the nozzle outlet is restricted.

Rotation of the valve mechanism is initiated by the temperature of the heated air flowing through the nozzle across the bimetallic strip rising above a desired operating temperature. This may occur if the air flow becomes restricted if the nozzle outlet becomes restricted or fully blocked.

The bimetallic coil expands and contracts with a change in temperature. In use, the normal heated air temperature may be in the range of 100 to 150°C. A temperature of approximately 115°C may be considered a normal operating temperature for example.

During normal use, the venting apertures should preferably remain closed to ensure the full unconstricted air flow is emitted from the nozzle outlet, meaning that there is no perceivable reduction in air flow.

In the event that the air flow becomes restricted, the bimetallic coil induces a rotation in the valve mechanism relative to the nozzle housing, allowing the heated air to vent out of the venting apertures in nozzle. The biometric coil may be constructed to expand and thus rotate the valve mechanism if the temperature exceeds 160-200t for

example.

In the illustrative embodiment of Fig la to 2b, a bimetallic coil is used. It will be appreciated that there are many other techniques for initiating a temperature dependent rotation of the nozzle. A thermistor may be used for example to sense the temperature. The thermistor may be coupled to a control circuit, either in the nozzle or in the hair dryer, which then initiates an actuator to rotate the valve mechanism.

The arrangement of Figures la to 2b is particularly useful as there are no external parts that hair may catch on.

In a further variant, a magnetic material may be used. It is well known that magnetic materials may lose their magnetic properties when heated above the Curie temperature (Tc). When the temperature falls below Tc they then regain their magnetic properties. A magnetic material may be selected such that To is approximately 180°C. By coupling the magnetic material to one of the nozzle housing or valve mechanism and a metallic material to the other, the valve mechanism may then rotate as the heated air flow exceeds the desired operating temperature. One or more magnets may be used, as well as one or more metallic elements.

Figures 3a and 3b show a second nozzle arrangement 30 using a temperature sensitive valve mechanism. Figure 3a shows a 3D projection of the second hair dryer nozzle 30 with closed venting apertures 36, 38 and Figure 3b shows a cross section through the same hair dryer nozzle 30 with the venting apertures 36,38 open.

Nozzle 30 has an inlet 34 couplable to a hair dryer and an outlet 32 for emitting air. As with the previous embodiment, the inlet is generally circular and the outlet is generally rectangular although other shapes may be used. The venting apertures 36, 38 are generally rectangular and extend along opposed sides of the nozzle between the inlet and the outlet. The venting apertures are covered by bimetallic strips which are arranged to form a valve mechanism. In the event that the temperature increases above the desired operating temperature, the bimetallic strips expand and bend outwards away from the nozzle, allowing heated air to be vented from the venting apertures on the sides of the nozzle. In this arrangement, the valve mechanism is thus outside the housing. Accordingly, in an enhancement to the arrangement of Figures 3a and 3b, the valves may be concealed by plastic flaps to prevent hair catching on the bimetallic strips.

Figure 4 shows the nozzle 30 of Figures 3a and 3b in use on a hair dryer 42. It will be understood however that any of the nozzles herein described may be used with a hair dryer 42. The hair dryer has an inlet 44 and outlet 46 to which the nozzle is coupled.

Within the hair dryer is a fan assembly to generate an air flow. Positioned in the air flow is a heater element to heat the air. If the nozzle outlet becomes restricted the air flow is reduced, meaning that the heater element may heat the air to an undesired temperature. In this way, the venting ensures that the temperature can be controlled to preferably say within the desired operating range.

Figures 5a, 5b, 6a and Sb show two alternative nozzle arrangements for pressure sensitive venting. Both generally operate in the same way, with the exception that the embodiment in Figures 5a and 5b comprises a rear facing vent and the embodiment in Figures Ga and 6b comprises a forward facing vent. The nozzles of Figures 5a to 6b have no moving parts, meaning that there is minimal risk of snagging hair on the nozzles.

In Figure 5a, a 3D projection of a first nozzle 50 with pressure sensitive venting is shown. Figure 5b shows a cross section of the nozzle 50 of Figure 5a. The nozzle has an inlet 54 and a nozzle outlet 52. The inlet 54 is couplable to a hair dryer air outlet.

Internal walls 55, 57 define a primary air flow channel between the nozzle inlet 54 and outlet 52 to direct the incoming air flow from the inlet 54 towards the outlet 52. The internal walls 55, 57 extend from the nozzle inlet 54 towards the nozzle outlet 52 through approximately 80% of the housing. The internal walls terminate before the nozzle outlet so that there is a gap between the nozzle outlet and the end of the internal walls.

Each gap is connected to a corresponding vent channel which is defined between the external walls of the nozzle housing and the internal walls 55, 57. Each vent channel has a venting aperture 56, 58 which face rearwards, in other words, generally facing the direction of the inlet 54.

In use and during normal operation, the nozzle 50 is coupled to a hair dryer and incoming heated air flows, taking the path of least resistance, from inlet 54 to outlet 52 through the primary air flow channel. In the event that the outlet 52 becomes restricted (wholly or partially) and the pressure rises within the nozzle, the air flow may be deflected into the vent channels and out of venting apertures 56, 58. In this way an excessive temperature within the nozzle and connected hair dryer is avoided as a sufficiently high airflow can be retained.

In this embodiment, the nozzle has a generally circular inlet and a generally rectangular outlet with a pair of vent channels, one either side of the outlet. The internal walls 55, 57 are flared from the inlet to the outlet to match the shape of the nozzle housing. It will be appreciated that different shapes may be used to achieve the same effect, for example, if the nozzle is completely cylindrical, an internal cylindrical member may be used to define the primary air flow channel and the vent channel(s).

In Figure 6a, a 3D projection of a further nozzle 60 with pressure sensitive venting with forward facing vents is shown. Figure 6b shows a cross section of the nozzle 60 of Figure 6a. This variant operates in a similar way to the arrangement of Figures 5a-5b.

Nozzle 60 has an inlet 64 and outlet 62. Internal walls 65a and 67a define a primary air flow channel between the nozzle inlet 64 and outlet 62 to direct the incoming air flow from the inlet 64 towards the outlet 62. As with the previous embodiment, a vent channel is formed either side of the outlet and leads to venting apertures 66 and 68 respectively. In this embodiment, the venting apertures 66, 68 face forwards, i.e. in the same direction as the outlet. Accordingly, each vent channel is generally U-shaped with a bend to direct air towards the forward facing venting aperture. Each vent channel is defined between the external walls of the nozzle housing and a pair of internal walls, 65a and 65b on one side, and 67a and 67b on the other.

In the event that the outlet 62 becomes restricted and the pressure rises within the nozzle, the air flow is deflected along the vent channels and out of venting apertures 66, 68. The main nozzle outlet 62 extends forward of venting apertures 66 and 68 (ie.

the vents are set back from the main nozzle outlet). The fact that the vents are set back relative to the nozzle outlet 62 means that they are unlikely to also become blocked.

This arrangement may be preferable for some users, because vented air is not directed back toward the hair dryer being held by a user or stylist.

Analysis has shown that the use of open vents is not overly detrimental to the air flow emitted from the nozzle outlet during normal use, meaning that a good level of styling and drying performance may be retained when the nozzles of Figures 5a-6b are used.

Figures 7a, 7b and 7c show a further nozzle arrangement for pressure sensitive venting. The arrangement is generally similar to that shown in Figures 5a and Sb and thus features in common are not described in detail. In this arrangement the vent channels comprise a pressure sensitive valve mechanism to control venting through the venting apertures. Figures 7a and 7b show 3D projections of the nozzle 70. In Figure 7a vent valves 75, 77 are in a closed position meaning that no air is vented through the vent apertures 76, 78. In Figures 7b and 7c, the vent valves 75, 77 are open.

As shown in Figure 7c, a vent valves 75, 77 is mounted in each vent channel. The vent valves 75, 77 are mounted to an external wall of the nozzle for rotational movement to open and close the vent channel. To prevent the vent valves opening during normal use as the hair dryer is moved and rotated about a person's head, the vent valves are preferably biased to the closed position, using a spring or any other conventional biasing means known to the skilled person.

In use, a nozzle 70 is coupled to a hairdryer and the incoming heated airflow takes the path of least resistance from inlet 74 to outlet 72. The vents are biased to a closed position (position A). In the event that the outlet 72 becomes restricted and the pressure rises within the nozzle, the airflow is deflected along the vent channels and towards the moveable vent valves. As the pressure increases the airflow within the vent channels overcomes the biasing force and pushes the vent valves open. The vent valves rotate about their pivot points towards position B, opening up the vent apertures allowing the heated air to escape.

The vent apertures are closed during normal operation means that there is minimal effect on normal airflow emitted from the nozzle outlet during styling.

Figures Ba and 8b show a further nozzle arrangement adopting pressure sensitive venting. In this variant the vents are forward facing. Referring first to Figure 8a, the nozzle has an inlet 84 and a nozzle outlet 82. On each side of the nozzle are vent valves 86, 88. In Figure 8a the valves are in the closed position such that airflow is directed out of the nozzle outlet 82. Referring now to Figure 8b, in the event that the nozzle outlet 82 becomes restricted the air pressure within the nozzle housing increases which forced the valves 86, 88 to pivot and open to allow air to vent from the nozzle. Much like the arrangement shown in Figures 7a to 7c, the valves are biased to the closed position and forced apart when pressure increases within the nozzle housing. When a restriction is removed from the nozzle outlet 82 or the overall airflow reduces within the nozzle housing (for example because a hairdryer is turned off), the valves 86, 88 may then return to their closed position. The valves may be biased to the closed position using conventional means well known to those skilled in the art, such as by the use of a spring.

Figures 9, 10 and 11 show three nozzle variants arranged to prevent a reduction in airflow in the event that a portion of the nozzle outlet becomes restricted. In Figures 9 to 11 each nozzle has a generally circular inlet (94, 104, 114) and a generally rectangular outlet (92, 102, 112) with an air flow channel between the inlet and outlet.

It will be appreciated that other shapes can be used.

The nozzle arrangements in Figures 9-1 1 are arranged to prevent, or at least minimise, a reduction in flow through the nozzle outlet without the use of the additional venting apertures which are spaced apart from the outlet as used in the previously described embodiments. The housing is configured to allow air to vent at an angle relative to the air flow channel. For example, the edge of the housing at the nozzle outlet is profiled to allow air flow to vent or escape when the outlet is restricted, e.g. when the nozzle outlet is in contact with a surface.

In Figure 9, the nozzle 90 comprises a plurality (in this example five) projections /fins 96 which extending forwards from the outlet. In use, when the nozzle outlet is unrestricted, air flows through the inlet and out the outlet in a direction parallel to the air flow channel. When the nozzle outlet is brought into contact with a surface, these projections 96 contact the surface and space the housing away from the surface thus reducing the possibility of the nozzle outlet becoming fully blocked. Heated air escapes through the passages defined between the projections at an angle which is generally perpendicular to the air flow channel.

In Figure 10, an edge of the outlet 106 is shaped to allow air flow to vent generally at right angles to the main air flow channel. The edge comprises a recess which in this example is curved portion 102 and which extends towards the inlet allowing air to escape upwards (as depicted) in the event that the outlet 106 becomes restricted. In other variants the recess may be on one or more sides, be smaller or larger, or there may also be multiple recesses as depicted in Figure 11. In the Figure 11 arrangement, the nozzle outlet 112 is arranged with a series of lobes 116 in a wave like formation providing multiple vent-like outlets to allow heating air to escape up and down (as depicted). The recesses are thus uniformly distributed across opposed edges of the outlet and each have the same size.

Figures 12a-12d show a variant arranged to use an air flow restriction to a positive effect. The nozzle 120 has an inlet 124 couplable to a hair dryer and an outlet 122 to emit heated air. As with previous embodiments, the inlet is generally circular and the outlet is generally rectangular with the housing curving to gradually change shape from inlet to outlet. In contrast to previous embodiments, the nozzle housing narrows to form a neck 127, creating a choke point. The neck 127 is narrower than the outlet 122.

A moveable member or choke 126, having an aerofoil like cross-section (with both sides evenly curved in this illustrative arrangement), projects from the front of the nozzle outlet 122. The choke acts as a projection to prevent the outlet becoming blocked by spacing the nozzle from a surface like the arrangement shown in Figure 9.

As explained below, the choke engages with the choke point to restrict air flow through the air flow channel.

The choke is coupled to a spring 125 providing means to bias the choke forwards to project out of the nozzle outlet 122. The other end of the spring is clamped to a section of the nozzle housing. In normal use, the choke is retained in its forward position as depicted in Figures 12a and 12b. Air flows across the curved surfaces of the choke between the housing and towards the front facing edge 127 of the choke 126. In this way a controlled and focussed stream of hot air for styling is retained. The choke is separated from the interior wall of the nozzle housing by a distance D1.

The choke may slide into the nozzle outlet from this forward position by depressing the choke with sufficient force to overcome the biasing forces. Referring now to Figures 12c and 12d, these shown the choke in depressed so that it has been pushed back further into the nozzle housing. When the choke is depressed, the fact that the nozzle housing narrows means that the space between the internal walls of the nozzle and the choke is reduced (Dr in Figure 12c) restricting the flow of heated air i.e. partially choking the air flow given that D1> Dr. In use, depressing the choke, for example against a head of hair being styled, provides a "heat boost" capability, allowing for a short period of increased temperature. This may be useful for styling or drying thicker quantities of hair. When the choke is moved away from a head or hair, the spring pushes the choke back to its forward position. The fact that the choke needs to be depressed also provides visual feedback to the stylist reminding them of an increase in temperature.

It will be appreciated that in the arrangement shown in Figures 12a-12d the level of choking and consequent heat boost may depend on the depth to which the moveable member is depressed.

Accurate control of the depression level of the choke may be particularly difficult to do during styling. Multiple different nozzles may therefore be provided to a user, each tuned to a different level of choking, provided different heat boost' settings.

In an enhancement, the level of choking may be controllable in the nozzle, meaning that the level of heat boost' may also be controllable. A nozzle may allow the choking to be set to different levels, by the use of an adjustable stop limiting the movement of

choke for example.

In variants of the nozzle of Figure 12a-d, additional vents may be used to prevent undesired increases in temperature should a user hold the choke in the heat boost' position for too long a time. These may take the form of any of the previously described embodiments, in particular those shown in Figures la to 3b which provide temperature sensitive venting mechanisms.

Temperature feedback to the user or stylist may also be useful, providing an indication of when the air temperature is within a preferred operating range, or when the temperature is excessive. Thermochromic inks are one way of addressing this.

Depicted in Figure 13a, a flat thermometer strip 132 may be secured to the nozzle. As show in Figure 13a, the thermometer strip 132 is positioned on the choke 126 of the nozzle arrangement of Figure 12a-12c. Heated air flows directly over this choke.

In the variant in Figure 13b, a section of the nozzle 136, preferably in proximity to the outlet (but not essential), is formed from a thermochromic polymer such that the section of the nozzle changes colour with temperature. This polymer may include an embedded thermochromic additive in order to initiate such a reaction. The additives may be such that the nozzle changes colour when an excessive temperature is reached. The entire nozzle housing, or the hair dryer casing may also be formed from a thermochromic polymer or include thermochromic additives.

Temperature feedback may also be provided in other ways. Shape memory material may also be used on the nozzle or hair dryer to indicate a change in temperature to a user or stylist. A temperature indicator formed from a shape memory material may be used to directly indicate (a visual change in the material), or indirectly indicate (be coupled to a temperature indicator) a change in temperature to above or below a temperature threshold. Conventional mechanical, or digital thermometers may also be integrated into a nozzle and/or the hair dryer.

All of the nozzle attachments previously described, including variants that would be apparent to the skilled person may be coupled to a hair dryer outlet. Furthermore, it will be appreciated that any of the above nozzle arrangements may form the nozzle of a hair dryer, being removeable or non-removeable.

No doubt many other effective alternatives will occur to the skilled person. It will be understood that the invention is not limited to the described embodiments and encompasses modifications apparent to those skilled in the art lying within the spirit and scope of the claims appended hereto.

Through out the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example comprising" and "comprise", means "including but not limited to, and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics or groups described in conjunction with a particular aspect, embodiment or example, of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Claims

CLAIMS: 1. A hair dryer nozzle comprising: a housing having an air inlet and an air outlet; a venting aperture in the housing for venting air from the housing; and a valve mechanism which is rnoveable relative to said housing between a closed position to close said venting aperture and an open position to open said venting aperture wherein said valve mechanism is configured to move from said closed position to said open position when a temperature within said housing exceeds a threshold value.
2. A hair dryer nozzle as claimed in claim 1, comprising a plurality of venting apertures.
3. A hair dryer nozzle as claimed in claim 1 or claim 2, wherein in the open position, the or each venting aperture has a combined area of at least 70% of the area of the nozzle outlet.
4. A hair dryer nozzle as claimed in any preceding claim, wherein the threshold value is 160°
5. A hair dryer nozzle as claimed in any preceding claim, wherein the valve mechanism is located within the nozzle housing.
6. A hair dryer nozzle as claimed in any preceding claim, wherein the valve mechanism is arranged to rotate relative to the housing.
7. A hair dryer nozzle as claimed in claim 6, wherein the valve mechanism comprises a valve aperture corresponding to each venting aperture wherein in the open position the or each venting aperture and valve aperture are at least partially aligned.
8. A hair dryer nozzle as claimed in claim 7, wherein the valve mechanism comprises a hub, one or more spokes extending radially from the hub, and a rim coupled to the one or more spokes; with the or each valve aperture located in said rim.
9. A hair dryer nozzle as claimed in any one of claims 6 to 8, wherein the valve mechanism comprises an actuator which is configured to change shape in response to a temperature change and to cause said rotation.A hair dryer nozzle as claimed in claim 9, wherein the actuator comprises a shape memory material.11. A hair dryer nozzle as claimed in claim 10, wherein the shape memory material comprises a bimetallic coil.12. A hair dryer nozzle as claimed in any one of claims 5 to 11 wherein the nozzle housing comprises an axle to which the valve mechanism is mounted.13. A hair dryer nozzle as claimed in claim 12 when dependent on claim 9, wherein the actuator is mounted on the axle.14. A hair dryer nozzle as claimed in any one of claims 1 to 5, wherein the valve mechanism is arranged to deflect relative to the housing.15. A hair dryer nozzle as claimed in claim 14, wherein the valve mechanism comprises a cover corresponding to each venting aperture, wherein the or each cover closes the corresponding venting aperture in the closed position and deflects to open the venting aperture in the open position.16. A hair dryer nozzle as claimed in claim 15, wherein the cover is made from a shape memory material which is configured to change shape responsive to changes in temperature.17. A hair dryer nozzle as claimed in claim 16, wherein the shape memory material comprises a bimetallic strip.18 A hair dryer nozzle as claimed in any one of claims 14 to 17, wherein the nozzle housing further comprises a cover over the valve mechanism.19. A method of controlling temperature within a hair dryer nozzle, the nozzle comprising: a housing having an air inlet and an air outlet; a venting aperture in the housing for venting air from the housing; and a valve mechanism the method comprising: moving the valve mechanism relative to the housing between a closed position to close the venting aperture and an open position to open the venting aperture wherein movement from the closed position to the open position is responsive to an increase in temperature within the housing above a threshold value.20. A hair dryer nozzle comprising: a housing having an air inlet, an air outlet and an air flow channel between the air inlet and air outlet; wherein the housing is configured at the outlet to allow air to vent at an angle relative to the air flow channel when flow through the air outlet parallel to the air flow channel is restricted.21. A hair dryer nozzle as claimed in claim 20, wherein the nozzle comprises at least one projection which extends beyond the air outlet.22. A hair dryer nozzle as claimed in claim 20, wherein at least one edge of the housing at the outlet end comprises a recess allowing air to vent at an angle relative to the air flow channel.23. A hair dryer nozzle as claimed in claim 22, wherein the at least one edge comprises a plurality of recesses.24. A hair dryer nozzle as claimed in any one of claims 1 to 18, comprising an air flow channel between the air inlet and air outlet; and wherein the housing is configured at the outlet to allow air to vent at an angle relative to the air flow channel when flow through the air outlet which is generally parallel to the air flow channel is restricted.25. A hair dryer nozzle comprising: a housing having an air inlet, an air outlet and an air flow channel between the air inlet and the air outlet; and a choke within the air flow channel; wherein the choke is moveable relative to the housing between a first position in which the air flow channel has a first throughput and a second position in which the air flow channel has a second, reduced throughput.26. A hair dryer nozzle as claimed in claim 25, wherein the choke is adjacent the air outlet.27. A hair dryer nozzle as claimed in claim 26 or 27, wherein in the first position the choke projects from the air outlet.28 A hair dryer nozzle as claimed in any one of claims 25 to 27, wherein the nozzle housing comprises a neck portion between the air inlet and air outlet having a smaller cross-sectional area than the air outlet.29. A hair dryer nozzle as claimed in claim 28, wherein in second position the choke is adjacent the neck portion 30. A hair dryer nozzle as claimed in any one of claims 25 to 29, further comprising biasing means arranged to bias the choke to the first position.31. A hair dryer nozzle as claimed in claim 30, wherein the biasing means comprise a spring.32. A hair dryer nozzle as claimed in any one of claims 25 to 31, further comprising a temperature indicator coupled to the nozzle housing or choke.33. A hair dryer nozzle as claimed in any one of claims 25 to 31, wherein the choke has a cross-section which is generally aerofoil shaped.34. A method of providing heat build-up in a hair dryer nozzle, the nozzle comprising: housing having an air inlet, an air outlet and an air flow channel between the air inlet and air outlet; and a choke within the air flow channel; the method comprising: restricting air flow through the air flow channel by moving a choke relative to the nozzle housing from a first position in which the air flow channel has a first throughput to a second position in which the air flow channel has a second reduced throughput.35. A hair dryer nozzle as claimed in any one of claims 1 to 19 or 25 to 33, comprising a temperature indicator coupled to the nozzle housing.36. A hair dryer nozzle comprising: a housing having an air inlet and an air outlet; and a temperature indicator coupled to the housing to indicate a change in temperature.37. A hair dryer nozzle as claimed in claim 35 or 36, wherein the temperature indicator comprises a thermochromic ink.38. A hair dryer nozzle as claimed in claim 35, 36 or 37, wherein the housing comprises a thermochromic polymer or additive to provide the temperature indicator.39. A hair dryer comprising the nozzle as claimed in any preceding claim.40. Apparatus substantially as herein described with reference to the accompanying drawings.