CN116782791A

CN116782791A - Hair care appliance

Info

Publication number: CN116782791A
Application number: CN202280012516.0A
Authority: CN
Inventors: T·珀内尔; A·皮尔; D·蒂贝茨; S·考特尼; R·库尔顿
Original assignee: Dyson Technology Ltd
Current assignee: Dyson Technology Ltd
Priority date: 2021-01-29
Filing date: 2022-01-06
Publication date: 2023-09-19
Also published as: GB2603176A; WO2022162339A1; GB2603176B; GB202101268D0

Abstract

An accessory for a hair care appliance, the accessory comprising an air inlet, an air outlet. The accessory has a curved surface adjacent to and downstream of the air outlet, and a pair of guide walls for guiding the air flow along the curved surface. A pair of guide walls extending outwardly from the curved surface. A hair care appliance has an air inlet, an air outlet and an airflow generator for generating an airflow from the air inlet to the air outlet. The hair care appliance has a curved surface adjacent to and downstream of the air outlet, and a pair of guide walls for guiding the air flow along the curved surface. A pair of guide walls extending outwardly from the curved surface.

Description

Hair care appliance

Technical Field

The present invention relates to a hair care appliance and an accessory for a hair care appliance.

Background

Hair care appliances are commonly used for drying and styling hair. If hair care appliances are used to style hair to create a smooth appearance, the presence of shorter or broken hair (sometimes referred to as flyaway) may affect the desired smooth appearance.

Disclosure of Invention

According to a first aspect of the present invention there is provided an accessory for a hair care appliance, the accessory comprising an air inlet, an air outlet, a curved surface adjacent to and downstream of the air outlet, and a pair of guide walls for guiding an air flow along the curved surface, the pair of guide walls extending outwardly from the curved surface.

The attachment according to the first aspect of the application may be advantageous in that the attachment comprises a curved surface adjacent to and downstream of the air outlet, and a pair of guide walls for guiding the air flow along the curved surface, the pair of guide walls extending outwardly from the curved surface.

In particular, the inventors of the present application have determined that a curved surface adjacent to and downstream of the air outlet may create a negative pressure region adjacent to the curved surface that attracts long hair toward the curved surface, and that air flow interacting with the hair also pushes short hair away from the curved surface. This may result in shorter hair passing through longer hair, for example through the side of the longer hair facing the head of the user, thereby providing a smooth hair finish. By providing a pair of guide walls extending outwardly from the curved surface, the influence of ambient air on the negative pressure region created by the airflow flowing along the curved surface may be suppressed in use, and an increased attraction of hair to the curved surface may result compared to a similar arrangement, for example, without the guide walls.

Each guide wall may be curved in form, for example having a curvature following the curvature of the curved surface. The guide walls of a pair of guide walls may be opposed to each other, for example, such that a channel is defined therebetween, the curved surface forming the base of the channel. The pair of guide walls may be spaced apart from each other along the curved surface, for example at opposite edges of the curved surface. The spacing between the guide walls may substantially correspond to the length of the air outlet. The curved surface may be substantially smooth and uninterrupted between the pair of guide walls. This allows the hair to be wrapped around the curved surface between the pair of guide walls in use.

The guide wall may protrude outwardly from the curved surface, e.g. the guide wall and the curved surface are integrally formed as a single piece.

The pair of guide walls may extend along substantially the entire length of the curved surface. This may ensure that the negative pressure region is maintained along substantially the entire length of the curved surface.

The pair of guide walls may include a height substantially equal to the height of the air outlet. This may ensure that in use a negative pressure region is maintained along substantially the entire height of the air jet exiting the air outlet.

The pair of guide walls may include a height substantially equal to the height of the air outlet in a region adjacent to the air outlet. The inventors of the present application have found that maintaining a region of negative pressure in the region adjacent the air outlet facilitates the generation of an air flow along the curved surface that generates a first force sufficient to attract relatively long hair toward the first surface, while also generating a second force that pushes relatively short hair away from the curved surface.

The pair of guide walls may include a radius of curvature greater than a radius of curvature of the curved surface. For example, the pair of guide walls may include a radius of curvature that is greater than a radius of curvature of the curved surface in a region adjacent to the air outlet. This ensures that in use the pair of guide walls provide their function in the region near the air outlet.

The pair of guide walls may include a height that varies along the length of the guide walls. The inventors of the present application have found that the guide wall provides the greatest influence in certain areas of the curved surface, for example in the area adjacent to the air outlet. The pair of guide walls may include a height that decreases in a direction away from the air outlet. By reducing the height of the guide wall in a direction away from the air outlet, less material may be required to form the guide wall than, for example, a constant height guide wall. The pair of guide walls may comprise a height that gradually decreases in a direction away from the air outlet, for example such that the height does not have a step change. The guide walls of a pair of guide walls may each comprise the same height and may be substantially symmetrical about an axis bisecting the space between the guide walls.

The pair of guide walls may comprise a constant height. This may provide certainty that the area of negative pressure created adjacent to the curved surface will not be affected along the length of the curved surface.

The attachment may be configured such that the air flow exiting the air outlet generates a first force that attracts hair toward the curved surface and a second force that pushes hair away from the curved surface. This may create a negative pressure area adjacent the curved surface that attracts long hair toward the curved surface, and the interaction of the air flow with the hair also pushes shorter hair away from the curved surface. This may result in shorter hair passing through longer hair, for example through the longer hair toward the side of the hair facing the user's head, thereby providing a smooth hair finish.

The ratio of the radius of curvature of the curved surface to the arc length of the curved surface is in the range of 0.04 to 0.63. By providing a curved surface, the ratio of the radius of curvature of the curved surface to the arc length of the curved surface is in the range of 0.04 to 0.63. The inventors of the present application have identified an arrangement which is particularly effective in achieving the above-described effects, in use, a smooth hair finish is achieved from hair styling accessories.

In use, the air flow leaving the air outlet may flow over a curved surface. The accessory may be configured such that, in use, a region of negative pressure is created in the vicinity of the curved surface. The curved surface may comprise a coanda surface, for example a convex surface along which the airflow is caused to adhere in use by the coanda effect.

The curved surface may comprise a radius of curvature in the range 16mm to 60 mm. The inventors have found that such a radius of curvature may be particularly effective in generating an air flow along the curved surface that generates a first force that attracts hair toward the curved surface and a second force that pushes hair away from the curved surface. The curved surface may comprise a substantially constant radius of curvature.

The curved surface may comprise an arc length of at least 95 degrees from the air outlet. The inventors have found that such arc lengths can be particularly effective in generating an air flow along the curved surface that generates a first force that attracts hair toward the curved surface and a second force that pushes hair away from the curved surface.

The ratio of the radius of curvature of the curved surface to the air flow velocity at the air outlet may be in the range of 0.33 to 2.00, for example in the range of 0.5 to 1.5. The inventors have found that such a ratio may be particularly effective in generating an air flow along the curved surface that generates a first force that attracts hair toward the curved surface and a second force that pushes hair away from the curved surface.

The air flow at the air outlet may comprise a velocity in the range of 30m/s to 45 m/s. The applicant has determined that speeds in the range 30m/s to 45m/s can be particularly effective in generating an air flow along a curved surface that generates a first force sufficient to attract relatively long hair toward the first surface, while also generating a second force that pushes relatively short hair away from the curved surface. In particular, too high a speed may cause shorter hairs to adhere to the curved surface and thus not push the shorter hairs off through the longer hairs, while too low a speed may be insufficient to attract the longer hairs to the curved surface in the first instance.

The shape and size of the air outlet may be such that the air flow at the air outlet comprises a velocity in the range of 30m/s to 45 m/s. The airflow generator may be configured to generate the airflow at a flow rate such that the airflow at the air outlet comprises a speed in the range 30m/s to 45 m/s.

The accessory may be configured such that the ratio of the airflow velocity at the air outlet to the flow velocity of the airflow generated by the airflow generator is in the range 2.14 to 5.63, for example in the range 2.6 to 3.6. The inventors have found that such a ratio can be particularly effective in generating an air flow along the curved surface that generates a first force sufficient to attract relatively long hair towards the first surface, while also generating a second force that pushes relatively short hair away from the curved surface.

The airflow generator may be configured to generate airflow at a flow rate in the range of 8L/s to 14L/s. The inventors have found that such a flow rate can be particularly effective in generating an air flow along a curved surface that generates a first force sufficient to attract relatively long hair toward the first surface, while also generating a second force that pushes relatively short hair away from the curved surface.

The opening cross-sectional area of the air outlet may be 140mm ² Up to 450mm ² Within a range of, for example, 280m ² To 350mm ² Within a range of (2). The inventors have found that such an open cross-sectional area can be particularly effective in generating an air flow along the curved surface that generates a first force that attracts hair toward the curved surface and a second force that pushes hair away from the curved surface.

The width of the air outlet may be in the range 70mm to 90mm, for example in the range 75mm to 85 mm. The air outlet may comprise a height in the region of 2mm to 5mm, for example a height in the region of 3.0 to 4.5 mm. The form of the air outlet may be substantially rectangular, for example such that the air flow leaving the air outlet has a substantially laminar form.

The ratio of the flow rate of the air flow generated by the air flow generator to the opening cross-sectional area of the air outlet may be in the range of 0.01 to 0.10. The inventors have found that such a ratio may be particularly effective in generating an air flow along the curved surface that generates a first force that attracts hair toward the curved surface and a second force that pushes hair away from the curved surface.

The accessory may include a planar surface adjacent to and extending rearwardly from the air outlet. In the case where the non-planar surface is provided to extend rearwardly from the air outlet, the smooth hair-facing may be disturbed when the accessory is moved relative to the hair in use, as may typically occur during styling operations. In the case where a roughened surface (e.g. a surface comprising protrusions such as bristles or the like) is provided extending rearwardly from the air outlet, such a roughened surface may disrupt hair that has been smoothed by the airflow from the air outlet when the accessory is moved relative to the hair in use. By providing a curved surface adjacent to and downstream of the air outlet and a flat surface adjacent to and extending rearwardly from the air outlet, a smooth hair finish can be created and maintained as the accessory is moved relative to the hair by a user in use.

The flat surface may also be used as a guiding surface to ensure that the accessory is positioned correctly with respect to the user's head so that the air flow leaving the air outlet can provide the above-described function.

The planar surface may be substantially smooth and uninterrupted in form. The planar surface may comprise a height in the range 5mm to 20 mm.

The accessory may be configured such that the planar surface contacts hair extending rearwardly from the air outlet when the accessory is moved relative to the hair in use, for example when the accessory is moved linearly in the direction of the hair from the root of the hair to the end of the hair in use.

The planar surface may comprise a substantially planar surface. This may help to maintain a smooth hair surface as the accessory moves relative to the hair in use, and may ensure that hair extending rearwardly from the air outlet is supported by the surface.

The planar surface may be inclined at an angle to the plane of the air outlet. This ensures that hair extending rearwardly from the air outlet contacts the flat surface, while hair downstream of the air outlet is attracted towards the curved surface in use. The planar surface may be at an oblique angle relative to a plane tangential to the curved surface at a point of the curved surface immediately adjacent the air outlet.

The accessory may include an end wall at an end of the curved surface. This may prevent the air flow from reaching the hand of the user holding the accessory during use.

The air outlet may comprise a fixed air outlet, such as an air outlet having a fixed cross-sectional area, length, and/or width. This ensures that the airflow characteristics of the attachment are constant for a given flow rate of the airflow generated by the airflow generator, thereby ensuring that an airflow is generated along the curved surface that results in a first force that attracts hair towards the curved surface, and a second force that pushes hair away from the curved surface. This may also provide a simpler accessory with fewer moving parts compared to an accessory with a variable air outlet, thus reducing the risk of malfunction.

The fitment may include a hollow body defining a flow path between an air inlet and an air outlet, the curved surface extending outwardly from the hollow body. When the curved surface extends outwardly from the hollow body, the hollow body and/or the remainder of the hair care appliance may be removed from the region of hair wound around the curved surface in use, thus preventing damage to the styling process performed in the region of the curved surface.

The central axis of curvature of the curved surface may be displaced from the central axis of the hollow body, e.g. parallel to and from the central axis of the hollow body, or orthogonal to and from the central axis of the hollow body.

The curved surface may include a first end attached to the hollow body and a second free end opposite the first end, e.g., the second free end is unattached to the hollow body. The first end may be attached to the hollow body in the region of the air outlet, for example such that the curved surface extends towards the outside of the air outlet. The curved surface may be generally arcuate in form.

The curved surface may be substantially smooth and uninterrupted in form. This may allow the hair to be wrapped around a curved surface in use.

The curved surface may be integrally formed with the hollow body, for example such that the curved surface and the hollow body are formed as a single piece. The air outlet may comprise a slot formed in the hollow body.

The accessory may include a single air outlet. This may ensure that there is no additional air outlet to disrupt the smoothing process using the hair care appliance and that the air flow leaving the air outlet has the desired characteristics, thereby creating a first force that attracts hair towards the curved surface and a second force that pushes hair away from the curved surface.

The air outlets may include a first air outlet located on a first side of the hair care appliance and a second air outlet located on a second side of the accessory opposite the first side of the hair care appliance, the curved surface being adjacent and downstream of each of the first and second air outlets, and the accessory including a first planar surface adjacent and extending rearwardly from the first air outlet and a second planar surface adjacent and extending rearwardly from the second air outlet. Providing the first and second air outlets and the first and second planar surfaces may enable the accessory to be used in a plurality of orientations while still achieving the above-described smoothing effect.

The curved surface may comprise a continuous surface extending between the first air outlet and the second air outlet. Such a continuous surface may facilitate attraction of hair to the curved surface when the attachment is used in multiple orientations. The guide wall extends continuously between the first air outlet and the second air outlet.

The accessory may include a switching mechanism for switching the accessory from a first configuration in which the airflow passes through the first air outlet and does not pass through the second air outlet to a second configuration in which the airflow passes through the second air outlet and does not pass through the first air outlet. This ensures that in use the airflow passes through only one side of the accessory. This may prevent the direction of the air flow from being away from the user's head in use, and may therefore result in reduced wasted air flow and more efficient styling. This also ensures that there is no stray air flow from air outlets that are not used as part of the moulding process, which could affect the moulding process in use.

The switching mechanism is actuatable to move the accessory between the first configuration and the second configuration under the force of gravity. This may provide a simple switching mechanism that does not require user input, thereby enhancing the user experience.

The central curve of the curvature of the curved surface may substantially coincide with the central axis of the airflow generator, e.g. substantially coincide with the central axis of a housing in which the airflow generator is arranged.

The curved surface may be displaced relative to the edge of the air outlet, for example such that the curved surface does not extend directly from the edge of the air outlet. The curved surface may be displaced from the edge of the air outlet by 0.5mm to 1.5mm. The curved surface may be displaced relative to the edge of the air outlet in a direction perpendicular to the edge of the air outlet, e.g. perpendicular to the longitudinally extending edge of the air outlet.

The accessory may include an internal baffle for turning the airflow from the airflow generator to toward the air outlet, for example, turning the airflow about 90 degrees toward the air outlet.

According to a second aspect of the present invention there is provided an accessory for a hair care appliance, the accessory comprising an airflow generator housed in a handle unit, the accessory comprising an air inlet for receiving an airflow from the airflow generator, an air outlet for discharging the airflow, a curved surface adjacent to and downstream of the air outlet, and a pair of guide walls for guiding the airflow along the curved surface, the pair of guide walls extending outwardly from the curved surface.

The hair care appliance may include a handle unit, an air flow generator housed within the handle unit, and an accessory releasably connected to the handle unit, the accessory including an air outlet, a curved surface, and a guide wall. Providing an air outlet and curved surface as part of a removable accessory may allow a user to selectively provide the functionality described herein.

The hair care appliance may comprise a heater for heating the air flow. This may provide increased styling flexibility and may, for example, enable the airflow to provide a drying function.

When the accessory comprises an internal baffle for turning the air flow from the air flow generator to towards the air outlet, for example the air flow is turned about 90 degrees towards the air outlet. This may allow the main portion of the hair care appliance housing the airflow generator to extend orthogonally relative to the air outlet, which may provide greater design flexibility and better ergonomics than, for example, a hair care appliance in which the air outlet is aligned with the main portion of the hair care appliance housing the airflow generator.

Optional features of the various aspects of the invention are equally applicable to other aspects of the invention where appropriate.

Drawings

Fig. 1 is a schematic view showing a hair care appliance according to the present invention;

fig. 2 is a schematic cross-sectional view through a handle unit of the hair care appliance of fig. 1;

fig. 3 is a schematic perspective view of a first embodiment of an attachment for the hair care appliance of fig. 1;

FIG. 4 is a schematic diagram illustrating the geometry of the accessory of FIG. 3;

FIG. 5 is a schematic diagram illustrating forces generated by airflow through the accessory of FIG. 3 in use;

FIG. 6 is a schematic perspective view of a modified version of the accessory of FIG. 3;

fig. 7 is a schematic perspective view of a second embodiment of an attachment for the hair care appliance of fig. 1;

FIG. 8 is a first side view of the accessory of FIG. 7;

FIG. 9 is a second side view of the accessory of FIG. 7;

FIG. 10 is a schematic diagram illustrating the accessory of FIG. 7 in a first configuration;

FIG. 11 is a schematic diagram illustrating the accessory of FIG. 7 in a second configuration;

fig. 12 is a schematic perspective view of another embodiment of a hair care appliance in accordance with the present invention;

fig. 13 is a schematic cross-sectional view through a handle unit of the hair care appliance of fig. 12;

fig. 14 is a schematic perspective view of an accessory of the hair care appliance of fig. 12;

fig. 15 is a schematic cross-sectional view through the accessory of fig. 13.

Detailed Description

A hair care appliance according to the present invention is schematically illustrated in fig. 1 and generally designated 10.

The hair care appliance 10 includes a handle unit 12 and an accessory 100 removably attached to the handle unit 12.

The handle unit 12 includes a housing 14, an airflow generator 16, a heater 18, and a control unit 20, as exemplarily shown in fig. 2.

The housing 14 is tubular and includes an air inlet 22 through which air flow is drawn into the housing 14 by the air flow generator 16 and an air outlet 24 through which air flow is exhausted from the housing 14 through the air outlet 32. The airflow generator 16 is housed within the housing 14 and includes an impeller 26 driven by a motor 28. The airflow generator is configured to generate an airflow at a flow rate in the range of 8 to 14L/S, for example, at a flow rate in the range of 10 to 13L/S. The dyson V9 digital motor produced by dyson technologies limited is a suitable airflow generator. A heater 18 is also housed within the housing 14 and includes a heating element 30 to optionally heat the air flow.

The control unit 20 includes electronic circuitry for the user interface 32 and the control module 34. A user interface 32 is provided on the outer surface of the housing 14 and is used to turn the hair care appliance 10 on and off, select flow rates (e.g., high, medium, and low), and select air flow temperatures (e.g., hot, medium, or cold). In the example of fig. 1, the user interface includes a plurality of slide switches, but other forms of user interfaces 32 are also contemplated, such as buttons, dials, or touch screens.

The control module 34 is responsible for controlling the airflow generator 16 and the heater 18 in response to inputs from the user interface 32. For example, in response to input from the user interface 32, the control module 34 may control the power or speed of the airflow generator 16 to adjust the airflow rate of the airflow, and the power of the heater 18 to adjust the temperature of the airflow.

The accessory 100 is schematically shown in fig. 3 and 4.

The accessory 100 includes a hollow body 102, a curved surface 104, and a pair of guide walls 106. The hollow body 102 includes an air inlet 108, an air outlet 110, a planar surface 112, and a plurality of internal baffles 114.

The air inlet 108 comprises a generally circular aperture formed in the hollow body 102, and the air inlet 108 is configured to receive an air flow from the air outlet 24 of the handle unit 12 when the accessory 100 is attached to the handle unit 12 in use. The perimeter of the air inlet 108 includes attachment features for releasably attaching the accessory 100 to the handle unit 12. The attachment features may take a variety of forms, not relevant to the present invention, and will not be described for the sake of brevity.

The air outlet 110 includes a substantially rectangular groove formed longitudinally along one side of the hollow body 110. The air outlet 110 has a width in the range of 70mm to 90mm, for example in the range of 75mm to 85mm, and a height in the range of 2mm to 5mm, for example in the range of 3.0mm to 4.5 mm. This gives an air outlet 110 of 140mm ² Up to 450mm ² In the range of, for example, 225.0mm ² To 382.5mm ² An overall opening cross-sectional area in the range of (2).

In the presently preferred embodiment, the width of the air outlet 110 is in the range of 77mm and the height of the air outlet 110 is in the range of 4.5 mm. The opening cross-sectional area of the air outlet 110 was 346.5mm ² Within a range of (2). The inventors of the present application have found that such dimensions for the air outlet 110 may provide advantageous effects, as described below.

The plurality of internal baffles 114 are curved in form and extend in a direction from the air inlet 108 to the air outlet 110. The plurality of internal baffles 114 are configured to turn the airflow in a direction from the air inlet 108 to a direction toward the air outlet 110 such that the airflow is turned approximately 90 degrees from the air inlet 108 to the air outlet 110. This may enable the handle unit 12 to extend orthogonally relative to the air outlet 110, which may provide greater design flexibility and better ergonomics than, for example, hair care appliances in which the air outlet is aligned with the handle unit of the hair care appliance.

The planar surface 112 is positioned adjacent to the air outlet 110 and extends rearward from the air outlet 110 such that the planar surface 112 extends rearward from an edge of the air outlet 110. The planar surface 112 is inclined at an angle, for example, in the range of 3-10 degrees, relative to the plane in which the air outlet 110 is disposed. The planar surface 112 is generally planar in form and is substantially smooth and uninterrupted, e.g., without protrusions, depressions or holes formed therein. The planar surface 112 has a height in the range of 5mm to 20 mm. The function of the flat surface 112 will be described below.

The curved surface 104 is schematically shown in fig. 4 and extends outwardly from the hollow body 102 in the region of the air outlet 110, e.g. a first edge 116 of the curved surface 104 is attached to the hollow body 102 adjacent the air outlet 110. Accordingly, curved surface 104 is positioned adjacent to air outlet 110 and downstream from air outlet 110. The second edge 118 of the curved surface 102 is a free edge such that the curved surface 104 is cantilevered with respect to the hollow body 102. The first edge 116 of the curved surface 104 is slightly displaced from the air outlet 110, for example by a distance in the range of 0.5-1.5 mm, such that there is a slight step drop from the air outlet 110 to the curved surface 102. It should be appreciated that in some embodiments, there may be no step down from the air outlet 110 to the curved surface 104.

The curved surface 102 is substantially smooth and uninterrupted in form such that no protrusions, depressions or holes are formed thereon. This may enhance the functionality of the accessory 100 as will be described below. The curved surface 102 has a radius of curvature in the range of 16mm to 60mm, such as in the range of 20mm to 40mm, and has an arc length in the range of 95 degrees to 360 degrees, such as in the range of 95 degrees to 120 degrees. In a presently preferred embodiment, curved surface 102 has a radius of curvature in the range of 20mm and an arc length in the range of 110 degrees. The inventors of the present application have found that such a geometry of the curved surface 102 may provide advantageous effects, as described below.

A pair of guide walls 106 are provided on opposite edges of the curved surface 102 that are orthogonal to the previously mentioned first 116 and second 118 edges of the curved surface 102. The guide wall 106 stands from the curved surface 102 and extends along the entire arc length of the curved surface 102. The guide wall 106 has a height that substantially corresponds to the height of the air outlet 110 and has a constant height along the length of the guide wall 106.

In use, the accessory 100 is attached to the handle unit 12. The airflow generator 16 generates an airflow from the air inlet 22 of the handle unit 12 to the air outlet 24 of the handle unit 12 such that the airflow flows from the air outlet 24 of the handle unit to the air inlet 108 of the accessory 100. The air flow passes from the air inlet 108 of the accessory through the hollow body 102 and is diverted by a plurality of internal baffles 114 to the air outlet 110 toward the accessory 100. The air flow exits the hollow body 102 via the air outlet 110 and passes over the curved surface 102.

The inventors of the present application have found that the air flow attaches to curved surface 102 by the coanda effect. When a bundle of hair is brought into the vicinity of accessory 100, the long hair of the bundle of hair is attracted to curved surface 102 by force f_pull and wraps at least partially around curved surface 102 due to the negative pressure area created by the air flow on curved surface 102. However, the pressure gradient across the hair strand also creates a force f_push, which can cause some airflow directly through the hair strand. Because of the location of this force relative to curved surface 102 and the rest of the hair bundle, the shorter hair is only loosely held at this point as compared to the longer hair held in place on curved surface 102. The shorter hair is blown through the hair bundle towards the user's head, while the longer hair remains outside the hair bundle, i.e. the part of the hair bundle facing away from the user's head. This provides a smooth hair finish to the hair after interaction with the hair care appliance 10 and associated accessory 100.

The interaction of the forces described above is schematically illustrated in fig. 5.

This effect can be optimized by appropriate modification of the geometries and parameters described herein. One such parameter that may provide an enhanced effect is the airflow velocity at the air outlet 110 of the accessory 100. In particular, too great a speed may cause shorter hairs to adhere to the curved surface 102 and thus not push the shorter hairs off through the longer hairs, while too low a speed may be insufficient to attract the longer hairs to the curved surface 102 in the first instance. Applicants have determined that speeds in the range of 30m/s to 45m/s can be particularly effective in generating an air flow along curved surface 102 that generates a first force sufficient to draw relatively long hair toward curved surface 102 while also generating a second force that pushes relatively short hair away from curved surface 102. In the presently preferred embodiment, the air flow velocity at the air outlet 110 is in the range of 35 m/s.

Another parameter that may provide enhanced efficacy for smoothing hair in the manner described above is: the ratio of the airflow velocity at the air outlet 110 to the airflow velocity generated by the airflow generator 16. In the embodiment of fig. 3 to 4, the ratio is in the range of 2.14 to 5.63, and in a particularly preferred embodiment, the ratio is in the range of 2.89. The inventors have found that such a ratio can be particularly effective in generating an air flow along curved surface 102 that generates a first force sufficient to draw relatively long hair toward curved surface 102, while also generating a second force that pushes relatively short hair away from curved surface 102.

Another parameter that may provide enhanced efficacy for smoothing hair in the manner described above is: the ratio of the airflow rate generated by the airflow generator 16 to the opening cross-sectional area of the air outlet 110. In the embodiment of fig. 3 to 4, the ratio is in the range of 0.01 to 0.10, and in a particularly preferred embodiment, the ratio is in the range of 0.04. The inventors have found that such a ratio can be particularly effective in generating an air flow along curved surface 102 that generates a first force sufficient to draw relatively long hair toward curved surface 102, while also generating a second force that pushes relatively short hair away from curved surface 102.

Another parameter that may provide enhanced efficacy for smoothing hair in the manner described above is: the ratio of the radius of curvature of the curved surface 102 to the airflow velocity at the air outlet 110. In the embodiment of fig. 3 to 4, the ratio is in the range of 0.33 to 2.00, and in a particularly preferred embodiment, the ratio is in the range of 0.57. The inventors have found that such a ratio can be particularly effective in generating an air flow along curved surface 102 that generates a first force sufficient to draw relatively long hair toward curved surface 102, while also generating a second force that pushes relatively short hair away from curved surface 102.

Another parameter that may provide enhanced efficacy for smoothing hair in the manner described above is: the ratio of the radius of curvature of the curved surface 102 to the arc length of the curved surface 102. In the embodiment of fig. 3 to 4, the ratio is in the range of 0.04 to 0.63, and in a particularly preferred embodiment, the ratio is in the range of 0.18. The inventors have found that such a ratio can be particularly effective in generating an air flow along curved surface 102 that generates a first force sufficient to draw relatively long hair toward curved surface 102, while also generating a second force that pushes relatively short hair away from curved surface 102.

In use, the attachment 100 may be moved along the length of a bundle of hair, for example in a direction from the root of the hair to the end of the hair. The flat surface 112 is positioned relative to the curved surface 102 such that the flat surface 112 contacts hair extending rearwardly from the air outlet 110 and hair downstream of the air outlet 110 contacts the curved surface 102. As previously mentioned, the planar surface 112 is substantially smooth and uninterrupted in form, without protrusions, depressions or holes formed thereon. As the hair care appliance 10 moves along the length of a bundle of hair in use, the flat surface 112 passes over hair that has been smoothed by interaction with the curved surface 102. In view of the smooth and uninterrupted nature of the flat surface 112, the flat surface 112 does not disrupt already smooth hair, resulting in a better hair finish compared to, for example, a corresponding hair care appliance having bristles and/or other air outlets located behind the air outlet 110.

As described above, a pair of guide walls 106 extend along opposite edges of the curved surface 102. This effectively creates an airflow channel in which a pair of guide walls 106 act as the walls of the channel, while the curved surface 102 acts as the base of the channel. The guide wall 106 inhibits interaction of ambient air with the airflow flowing along the curved surface 102 in use, which may maintain a negative pressure region created by the airflow flowing along the curved surface 102.

Although depicted in fig. 3-4 as having a guide wall 106 that is constant in height along the curved surface 102, it has been found that the guide wall 106 may be most effective in the area of the air outlet 110. In an alternative embodiment, as schematically shown in fig. 6, the accessory 100 has a guiding wall 120 that decreases in height in a direction away from the air outlet 110. Thus, less material may be required to form the guide wall 120 than, for example, a constant height guide wall 106.

In the above-described embodiment, the accessory has a single fixed air outlet 110, which is in fact a slot formed in the hollow body 104.

An alternative embodiment of an accessory 200 having a plurality of air outlets is schematically illustrated in fig. 7-11.

Accessory 200 includes inlet barrel 202, outlet body 204, and baffle 206. The inlet barrel 202 is substantially cylindrical in form and includes an air inlet 208, the air inlet 208 being configured to receive an air flow from the air outlet 24 of the handle unit 12 when the accessory 200 is attached to the handle unit 12 in use. The perimeter of the air inlet 208 includes attachment features for releasably attaching the accessory 200 to the handle unit 12. The attachment features may take a variety of forms, not relevant to the present invention, and will not be described for the sake of brevity.

Inlet barrel 202 defines a curved surface 210. The curved surface 210 is substantially smooth and uninterrupted in form such that no protrusions, depressions or holes are formed thereon. This may enhance the functionality of accessory 200, which will be described below. The curved surface 210 has a radius of curvature in the range of 16mm to 60mm, for example 20mm to 40mm, and has an arc length in the range of 95 degrees to 360 degrees. In a presently preferred embodiment, curved surface 210 has a radius of curvature in the range of 20mm and an arc length in the range of 296 degrees. The inventors of the present application have found that such a geometry of curved surface 210 may provide advantageous effects, as described below.

Inlet barrel 202 includes a central pivot axis 212 about which baffle 206 is pivotable, as described below.

The outlet body 204 includes a first end 214, a second end 216, and a connection 218 extending between the first end 214 and the second end 216. First end 214 is generally tear-drop in form and includes an aperture (not shown) through which inlet barrel 202 extends such that at least a portion of first end 214 extends annularly about inlet barrel 202.

The second end 216 has substantially the same tear drop form as the first end 214, but is substantially solid and defines a cap for the inlet barrel 202.

The connection 218 extends along the curved surface 210 of the inlet barrel 202 between the apices of the first end 214 and the second end 216. The connection 218 has the general form of a triangular prism.

The connection 218 has a first air outlet 220, a second air outlet 222, a first planar surface 224, and a second planar surface 226. The first air outlet 220 and the second air outlet 222 are located on opposite sides of the connection 218 such that the first air outlet 220 and the second air outlet 222 are located on opposite sides of the inlet barrel 202 and thus on opposite sides of the accessory 200. The curved surface 210 of the inlet barrel 202 is positioned adjacent to and downstream of each of the first air outlet 220 and the second air outlet 222 such that the curved surface 210 extends continuously between the first air outlet 220 and the second air outlet 222. The dimensions of the first end 214 and the second end 216 are slightly larger than the dimensions of the inlet barrel 202 such that the guide wall 227 is formed around the perimeter of the curved surface 210.

Each of the first air outlet 220 and the second air outlet 222 is generally rectangular in overall form. The first air outlet 220 and the second air outlet 222 each have a width in the range of 70mm to 90mm, for example in the range of 75mm to 85mm, and a height in the range of 2mm to 5mm, for example in the range of 3mm to 4.5 mm. This gives the first air outlet 220 and the second air outlet 222 at 140mm, respectively ² Up to 450mm ² Within a range of, for example, 225mm ² To 382.5mm ² An overall opening cross-sectional area in the range of (2).

In the presently preferred embodiment, a first air outlet 220 and a second air outlet222 is in the range of 77mm, and the height of each of the first air outlet 220 and the second air outlet 222 is in the range of 4.5 mm. The open cross-sectional area of each of the first air outlet 220 and the second air outlet 222 is 346.5mm ² Within a range of (2). The inventors of the present application have found that such dimensions for each of the first air outlet 220 and the second air outlet 222 may provide advantageous effects, as described below. Each of the first air outlet 220 and the second air outlet 222 in the embodiment of fig. 7-11 is divided into smaller sub-outlets, but the overall dimensions of the first air outlet 220 and the second air outlet 222 are as given above.

The first planar surface 224 is positioned adjacent to the first air outlet 220 and extends rearwardly from the first air outlet 220, while the second planar surface 226 is positioned adjacent to the second air outlet 222 and extends rearwardly from the second air outlet 222. The first planar surface 224 and the second planar surface 226 are located on either side of the apex of the connection such that the first planar surface 224 and the second planar surface 226 are located on opposite sides of the attachment 200. The first planar surface 224 and the second planar surface 226 are generally planar in form and are substantially smooth and uninterrupted, e.g., have no protrusions, depressions, or holes formed therein. The first and second planar surfaces 224, 226 are inclined at an angle relative to the plane on which the respective first and second air outlets 220, 222 are formed.

The connection 218 further includes a first air flow channel 228 and a second air flow channel 230, which, as described below, may be selectively placed in fluid communication with the interior of the inlet barrel 202.

The baffle 206 includes a first blocking surface 232, a second blocking surface 234, a flow channel 236, a connecting arm 238, and a plurality of weights 240.

The first and second blocking surfaces 232, 234 are substantially solid in form and selectively block the respective first and second air flow passages 228, 230. A flow slot 236 is formed between the first and second blocking surfaces 232, 234 and selectively provides fluid communication between the first and second airflow passages 228, 230 and the interior of the inlet barrel 202. The connecting arms 238 are located at upper and lower regions of the baffle 206 and pivotally connect the baffle 206 to the central pivot axis 212 of the inlet barrel 202. The first and second blocking surfaces 232, 234 are slidably received within a channel 242 formed in the wall of the inlet barrel 202 to effect pivotal movement of the deflector 206 relative to the inlet barrel 202. A plurality of weights 240 are embedded in the first and second blocking surfaces 232, 234. The baffle 206 also has a plurality of internal baffles 244 that divert the air flow from the air inlet 208 toward the flow slot 236.

The baffle 206 is movable within the attachment 200 between a first configuration shown in fig. 10 and a second configuration shown in fig. 11.

In a first configuration, i.e., a configuration in which the attachment 200 is held to the left of the user's head, with the first planar surface 224 in contact with the hair, the plurality of weights 240 ensure that the flow slots 236 are aligned with the first air flow channel 228 and the second blocking surface 234 is aligned with the second air flow channel 230. Thus, in the first configuration, airflow may escape from the first air outlet 220 but not from the second air outlet 222.

In a second configuration, i.e., a configuration in which the attachment 200 is held to the right of the user's head, with the second planar surface 226 in contact with hair, the plurality of weights 240 ensure that the flow slot 236 is aligned with the second air flow channel 230 and the first blocking surface 232 is aligned with the first air flow channel 228. Thus, in the second configuration, airflow may escape from the second air outlet 222, but not from the first air outlet 220.

Thus, the accessory 200 can be easily used on either side of a user's head, wherein the plurality of weights 240 provide a switching mechanism that can automatically switch the baffle 206 between the first configuration and the second configuration without user interaction.

Similar to the accessory 100 of fig. 3 and 4, in use, the accessory 200 is attached to the handle unit 12. The airflow generator 16 generates an airflow from the air inlet 22 of the handle unit 12 to the air outlet 24 of the handle unit 12 such that the airflow flows from the air outlet 24 of the handle unit to the air inlet 208 of the accessory 200. The airflow flows from the air inlet 208 of the attachment through the inlet barrel 202 and is diverted by the plurality of internal baffles 244 toward the flow channel 236. The airflow exits the accessory via either the first air outlet 220 or the second air outlet 222, depending on which of the first configuration and the second configuration the accessory is in, and across the curved surface 210.

The inventors of the present application have found that the air flow attaches to curved surface 210 by the coanda effect. When a bundle of hair is brought into the vicinity of accessory 200, the long hair of the bundle of hair is attracted to curved surface 210 and wraps at least partially around curved surface 102 due to the negative pressure area created by the air flow over curved surface 210. However, pressure gradients across the hair strand can also create forces that can cause some airflow directly through the hair strand. Because of the location of this force relative to curved surface 210 and the rest of the hair bundle, the shorter hair is only loosely held at this point as compared to the longer hair held in place on curved surface 210. The shorter hair is blown through the hair bundle towards the user's head, while the longer hair remains outside the hair bundle, i.e. the part of the hair bundle facing away from the user's head. This provides a smooth hair finish to the hair after interaction with the hair care appliance 10 and associated accessory 100.

This effect can be optimized by appropriate modification of the geometries and parameters described herein. One such parameter that may provide an enhanced effect is the air flow velocity at the air outlets 220,222 of the accessory 200. In particular, too great a speed may cause shorter hairs to adhere to the curved surface 210 and thus not push the shorter hairs off through the longer hairs, while too low a speed may be insufficient to attract the longer hairs to the curved surface 210 in the first instance. Applicants have determined that speeds in the range of 30m/s to 45m/s can be particularly effective in generating an air flow along curved surface 210 that generates a first force sufficient to draw relatively long hair toward curved surface 210 while also generating a second force that pushes relatively short hair away from curved surface 210. In the presently preferred embodiment, the air flow velocity at the air outlets 220,222 is in the range of 35 m/s.

Another parameter that may provide enhanced efficacy for smoothing hair in the manner described above is: the ratio of the airflow velocity at the air outlets 220,222 to the airflow velocity generated by the airflow generator 16. In the embodiment of fig. 7 to 11, the ratio is in the range of 2.14 to 5.63, and in a particularly preferred embodiment, the ratio is in the range of 2.89. The inventors have found that such a ratio may be particularly effective in generating an air flow along curved surface 210 that generates a first force sufficient to draw relatively long hair toward curved surface 210, while also generating a second force that pushes relatively short hair away from curved surface 210.

Another parameter that may provide enhanced efficacy for smoothing hair in the manner described above is: the ratio of the airflow rate generated by the airflow generator 16 to the open cross-sectional area of one of the air outlets 220, 222. In the embodiment of fig. 7 to 11, the ratio is in the range of 0.01 to 0.10, and in a particularly preferred embodiment, the ratio is in the range of 0.04. The inventors have found that such a ratio may be particularly effective in generating an air flow along curved surface 210 that generates a first force sufficient to draw relatively long hair toward curved surface 210, while also generating a second force that pushes relatively short hair away from curved surface 210.

Another parameter that may provide enhanced efficacy for smoothing hair in the manner described above is: the ratio of the radius of curvature of the curved surface 210 to the airflow velocity at the air outlets 220, 222. In the embodiment of fig. 7 to 11, the ratio is in the range of 0.33 to 2.00, and in a particularly preferred embodiment, the ratio is in the range of 0.57. The inventors have found that such a ratio may be particularly effective in generating an air flow along curved surface 210 that generates a first force sufficient to draw relatively long hair toward curved surface 210, while also generating a second force that pushes relatively short hair away from curved surface 210.

Another parameter that may provide enhanced efficacy for smoothing hair in the manner described above is: the ratio of the radius of curvature of the curved surface 210 to the arc length of the curved surface 210. In the embodiment of fig. 7 to 11, the ratio is in the range of 0.04 to 0.63, and in a particularly preferred embodiment, the ratio is in the range of 0.07. The inventors have found that such a ratio may be particularly effective in generating an air flow along curved surface 210 that generates a first force sufficient to draw relatively long hair toward curved surface 210, while also generating a second force that pushes relatively short hair away from curved surface 210.

In use, the attachment 200 may be moved along the length of a bundle of hair, for example in a direction from the root of the hair to the end of the hair. The first planar surface 224 and the second planar surface 226 are positioned relative to the curved surface 210 such that the planar surfaces 224, 226 contact hair extending rearward from the air outlets 220, 222 and hair downstream of the air outlets 220, 222 contacts the curved surface 210. As previously mentioned, the planar surfaces 224, 226 are substantially smooth and uninterrupted in form, without protrusions, depressions or holes formed thereon. As the hair care appliance 10 and associated accessory 100 move along the length of a bundle of hair in use, the flat surfaces 224, 226 pass over hair that has been smoothed by interaction with the curved surface 210. In view of the smooth and uninterrupted nature of the flat surfaces 224, 226, the flat surfaces 224, 226 do not disrupt already smooth hair, resulting in a better hair finish than, for example, corresponding hair care appliances having bristles and/or other air outlets located behind the air outlets 220, 222.

Guide walls 244 extend along opposite edges of curved surface 210. This effectively creates an airflow channel in which the guide wall 244 acts as a wall of the channel, while the curved surface 210 acts as a base of the channel. The guide wall 244 inhibits interaction of ambient air with the airflow flowing along the curved surface 210 in use, which may maintain a negative pressure region created by the airflow flowing along the curved surface 210.

An alternative embodiment of a hair care appliance 300 is schematically illustrated in fig. 12-15.

The hair care appliance 300 includes a handle unit 302 and an accessory 306. The handle unit 302 includes a handle portion 308, a head portion 310, an airflow generator 312, and a heater 314.

The handle portion 308 is generally cylindrical and hollow in form and houses an airflow generator 312. The handle portion 308 has an air inlet 316 in the form of a plurality of perforations at a first end 318 of the handle portion 308.

The head 310 is generally cylindrical and hollow in form and is disposed at the second end 320 of the handle portion 308 with the central axis of the head 310 being orthogonal to the central axis of the handle portion 308 such that the handle unit 302 is generally T-shaped in form. The head 310 houses a heater 314. The head 310 includes an aperture 322 and an air outlet 324 through which air is entrained through the aperture 322. The air outlet 324 is generally annular about the periphery of the aperture 322.

The accessory 304 is schematically shown in fig. 14 and 15.

The attachment 304 includes an inlet body 326, a curved surface 328, a guide wall 330, and an end wall 332. The inlet body 326 is generally hollow in form and includes a rearwardly extending projection 334 for insertion into the aperture 322 and an annular inlet 336 extending around the rearwardly extending projection 334. The inlet body 326 acts as a plenum for receiving airflow from the air outlet 324 of the handle unit 302. The inlet body 306 includes an air outlet 338 in the form of a slot having a height that varies along its width with a height peak at a center point of the width. The width of the air outlet 338 is in the range of 81 millimeters and the height varies from a minimum of 3 millimeters to a maximum of 4 millimeters. The air outlet 338 has a diameter of 292.7mm ² An overall opening cross-sectional area in the range of (2).

The curved surface 328 extends outwardly from the inlet body 326 in the region of the air outlet 338. Accordingly, curved surface 328 is positioned adjacent air outlet 338 and downstream of air outlet 110. The curved surface 328 is substantially smooth and uninterrupted in form such that no protrusions, depressions or holes are formed thereon. This may enhance the functionality of the accessory 100 as will be described below. Curved surface 328 has a radius of curvature in the range of 20mm and has an arc length in the range of 110 degrees. The inventors of the present application have found that such a geometry of curved surface 328 may provide advantageous effects, as described below.

Guide walls 330 are provided on opposite edges of curved surface 328. The guide wall 330 stands from the curved surface 328 and extends along the entire arc length of the curved surface 328. The guide wall 328 has a height that substantially corresponds to the height of the air outlet 338 and has a constant height along the length of the guide wall 106. End wall 332 is located at an end of curved surface 328 remote from air outlet 338 and extends between guide walls 330. When the accessory 304 is attached to the handle unit 302 in use, the end wall 332 prevents airflow from moving toward the handle portion 308 of the handle unit 302.

In use, the accessory 304 is attached to the handle unit 302. The airflow generator 312 generates an airflow from the air inlet 316 of the handle unit 302 to the air outlet 324 of the handle unit 302 such that the airflow flows from the air outlet 324 of the handle unit 302 to the air inlet 336 of the accessory 304. Air flow from the air inlet 336 of the accessory flows through the inlet body 326 to the air outlet 338. The airflow exits the attachment 304 via the air outlet 338 and passes over the curved surface 328.

The inventors of the present application have found that the air flow attaches to curved surface 328 by the coanda effect. When a bundle of hair is brought into proximity of accessory 304, long hair is attracted to curved surface 328 and wraps at least partially around curved surface 102 due to the negative pressure area created by the air flow over curved surface 328. However, pressure gradients across the hair strand can also create forces that can cause some airflow directly through the hair strand. Because of the location of this force relative to curved surface 328 and the rest of the hair bundle, the shorter hair is only loosely held at this point as compared to the longer hair held in place on curved surface 328. The shorter hair is blown through the hair bundle towards the user's head, while the longer hair remains outside the hair bundle, i.e. the part of the hair bundle facing away from the user's head. This provides a smooth hair finish to the hair after interaction with the hair care appliance 300 and associated accessory 100.

This effect can be optimized by appropriate modification of the geometries and parameters described herein. One such parameter that may provide an enhanced effect is the air flow velocity at the air outlet 338 of the accessory 304. In particular, too great a speed may cause shorter hairs to adhere to curved surface 328 and thus not push the shorter hairs off through longer hairs, while too low a speed may be insufficient to attract longer hairs to curved surface 328 in the first instance. Applicants have determined that speeds in the range of 30m/s to 45m/s can be particularly effective in generating an air flow along curved surface 328 that generates a first force sufficient to draw relatively long hair toward curved surface 328, while also generating a second force that pushes relatively short hair away from curved surface 328. In the presently preferred embodiment, the air flow velocity at the air outlet 338 is in the range of 43 m/s.

Another parameter that may provide enhanced efficacy for smoothing hair in the manner described above is: the ratio of the airflow velocity at the air outlet 338 to the airflow velocity generated by the airflow generator 312. In the embodiment of fig. 12 to 15, the ratio is in the range of 2.14-5.63, and in a particularly preferred embodiment, the ratio is in the range of 3.14. The inventors have found that such a ratio can be particularly effective in creating an air flow along curved surface 328 that creates a first force sufficient to draw relatively long hair toward curved surface 328, while also creating a second force that pushes relatively short hair away from curved surface 328.

Another parameter that may provide enhanced efficacy for smoothing hair in the manner described above is: the ratio of the airflow rate generated by the airflow generator 312 to the open cross-sectional area of the air outlet 338. In the embodiment of fig. 12 to 15, the ratio is in the range of 0.01 to 0.10, and in a particularly preferred embodiment, the ratio is in the range of 0.04. The inventors have found that such a ratio can be particularly effective in creating an air flow along curved surface 328 that creates a first force sufficient to draw relatively long hair toward curved surface 328, while also creating a second force that pushes relatively short hair away from curved surface 328.

Another parameter that may provide enhanced efficacy for smoothing hair in the manner described above is: the ratio of the radius of curvature of curved surface 328 to the airflow velocity at air outlet 338. In the embodiment of fig. 13 to 15, the ratio is in the range of 0.33 to 2.00, and in a particularly preferred embodiment, the ratio is in the range of 0.47. The inventors have found that such a ratio can be particularly effective in creating an air flow along curved surface 328 that creates a first force sufficient to draw relatively long hair toward curved surface 328, while also creating a second force that pushes relatively short hair away from curved surface 328.

Another parameter that may provide enhanced efficacy for smoothing hair in the manner described above is: the ratio of the radius of curvature of curved surface 328 to the arc length of curved surface 328. In the embodiment of fig. 12 to 15, the ratio is in the range of 0.04 to 0.63, and in a particularly preferred embodiment, the ratio is in the range of 0.18. The inventors have found that such a ratio can be particularly effective in creating an air flow along curved surface 328 that creates a first force sufficient to draw relatively long hair toward curved surface 328, while also creating a second force that pushes relatively short hair away from curved surface 328.

Guide walls 330 extend along opposite edges of curved surface 328. This effectively creates an airflow channel in which the guide wall 330 acts as a wall of the channel, while the curved surface 210 acts as a base of the channel. The guide wall 330 inhibits interaction of ambient air with the airflow flowing along the curved surface 328 in use, which may maintain a negative pressure region created by the airflow flowing along the curved surface 328.

Although described herein as an embodiment with a releasable attachment, embodiments are also contemplated wherein the hair care appliance is not a hair care appliance comprising a handle unit and an attachment, but rather a single piece unit, for example in the form of a combination of the aforementioned handle unit and attachment.

Claims

1. An accessory for a hair care appliance, the accessory comprising: an air inlet; an air outlet; a curved surface adjacent to and downstream of the air outlet; and a pair of guide walls for guiding the air flow along the curved surface, the pair of guide walls extending outwardly from the curved surface.

2. The accessory of claim 1, wherein the pair of guide walls extend along substantially the entire length of the curved surface.

3. An accessory according to any one of the preceding claims, wherein the pair of guide walls comprises a height substantially equal to the height of the air outlet.

4. An accessory according to any one of the preceding claims, wherein the pair of guide walls comprises a height substantially equal to the height of the air outlet in a region adjacent the air outlet.

5. An accessory according to any one of the preceding claims wherein the pair of guide walls comprises a radius of curvature greater than the radius of curvature of the curved surface.

6. An accessory according to any one of the preceding claims, wherein the pair of guide walls comprises a radius of curvature which is greater than the radius of curvature of the curved surface in a region adjacent the air outlet.

7. An accessory according to any one of the preceding claims, wherein the pair of guide walls comprises a height that varies along the length of the guide walls.

8. An accessory according to any one of the preceding claims, wherein the pair of guide walls comprises a height that decreases in a direction away from the air outlet.

9. The accessory according to any one of claims 1 to 6, wherein the pair of guide walls comprises a constant height.

10. An accessory according to any one of the preceding claims, wherein the accessory is configured such that the air flow exiting the air outlet generates a first force that attracts hair towards the curved surface and a second force that pushes hair away from the curved surface.

11. A hair care appliance, the hair care appliance comprising: an air inlet; an air outlet; an air flow generator for generating an air flow from the air inlet to the air outlet; a curved surface adjacent to and downstream of the air outlet; and a pair of guide walls for guiding the air flow along a curved surface, the pair of guide walls extending outwardly from the curved surface.

12. A hair care appliance according to any preceding claim, wherein the hair care appliance comprises a handle unit within which the airflow generator is housed, and an accessory releasably attached to the handle unit, the accessory comprising the air outlet, the curved surface and the guide wall.