Field of the Invention

The present invention relates to a haircare appliance, and an attachment for a haircare appliance.

Background of the Invention

Haircare appliances are typically used to dry and style hair. Where haircare appliances are used to style hair to create a smooth appearance, the presence of shorter, broken or individual hairs that protrude from the main bulk of the hair, sometimes referred to as flyaways, may impact on the desired smooth appearance.

Summary of the Invention

According to a first aspect of the present invention there is provided a haircare appliance comprising: an air inlet, an air outlet, an airflow generator for generating an airflow from the air inlet to the air outlet, and a curved surface adjacent to and downstream of the air outlet, wherein: the haircare appliance is configured such that airflow emitted from the air outlet generates a first force to attract hair toward the curved surface, and a second force to push hair away from the curved surface; the curved surface is between the air outlet and the air inlet; the air inlet is configured to receive airflow emitted from the air outlet; and the haircare appliance is configured to generate a suction force at the air inlet to attract hair toward the curved surface.

Providing a curved surface adjacent to and downstream of the air outlet may generate a negative pressure region adjacent to the curved surface which attracts hair toward the curved surface, with the airflow interaction with hair also pushing shorter hairs away from the curved surface due to the second force. This may result in shorter hairs, such as broken hairs, being pushed through the longer hairs, for example through the longer hairs toward the side of hair facing a user’s head, such that longer hairs lie above the shorter hairs and hence a smooth finish is provided. Air emitted from the air outlet passes over the curved surface to generate the first and second forces.

In order to generate a sufficient pressure differential to attract hair toward the curved surface, a relatively high airflow velocity at the air outlet is typically required. However, provision of the air inlet at the opposite end of the curved surface to the air outlet can help to enhance the negative pressure region by generating a suction force at the air inlet to attract hair toward the curved surface and recirculating air through the haircare appliance.

The suction generated at the air inlet by the airflow generator draws the hair toward the air inlet and the curved surface, supplementing the first force generated by airflow emitted from the air outlet. Thus, the smooth finish described above may be provided with lower airflow velocity at the air outlet than a haircare appliance with the air inlet located elsewhere. Accordingly, less power may be required for powering the airflow generator to produce a comparable smooth finish such that a smaller airflow generator can be used. In turn, a smaller airflow generator may be required. This may be particularly beneficial for a battery- operated portable haircare appliance.

The curved surface may comprise a Coanda surface, for example a convex surface along which airflow is attached as a result of the Coanda effect in use.

The curved surface may be substantially smooth and uninterrupted in form. This may enable hair to wrap around the curved surface in use. This may help prevent flyaway hairs and/or static forming during use of the haircare appliance, which may provide a smoother finish. For example, the curved surface may be free of protrusions such as bristles.

The air outlet may be configured to emit airflow tangentially to the curved surface. This may help to increase a distance along the curved surface along which hair remains attached to the curved surface and thus enhance the negative pressure region and thus the smoothing performance of the haircare appliance.

The curved surface may subtend an angle in the region of 60 to 150 degrees from the air outlet to the air inlet. Such arc lengths may be effective in generating an airflow along the curved surface that results in a first force to attract hair toward the curved surface, and a second force to push hair away from the curved surface. The first force may diminish as the distance between the air outlet and the air inlet increases.

The curved surface may subtend an angle of around 90 degrees from the air outlet to the air inlet. Such an arc length may be particularly effective in generating an airflow along the curved surface that results in a first force to attract hair toward the curved surface, and a second force to push hair away from the curved surface to sort hair to provide a smooth finish.

The curved surface may have a radius of curvature in the region of 20 mm to 100 mm. Such a radius of curvature may be particularly effective in generating an airflow along the curved surface that results in a first force to attract hair toward the curved surface, and a second force to push hair away from the curved surface. The curved surface may comprise a substantially constant radius of curvature.

A cross-sectional area of the air inlet may be in the region of 1 .5 to 3 times greater than a cross-sectional area of the air outlet. This may provide a particularly efficient arrangement, permitting lower airflow velocity at the air outlet whilst still providing an acceptable smooth finish.

The air outlet may comprise a fixed air outlet and the air inlet may comprise a fixed air inlet. For example, an air outlet and/or air inlet of fixed cross-sectional area, length and/or width. This may ensure that airflow characteristics of the haircare appliance are constant for a given flow rate of airflow generated by the airflow generator, thereby ensuring that an airflow is generated along the curved surface that results in a first force to attract hair toward the curved surface, and a second force to push hair away from the curved surface. This may also provide a simpler haircare appliance with fewer moving parts, and hence a reduced risk of failure, compared to a haircare appliance with a variable air outlet or air inlet.

The air inlet and the air outlet may have widths corresponding to a width of the curved surface. This may maximise the amount of hair that can be smoothed during for a given overall size of the haircare appliance. This may also provide a relatively constant force across the width of the curved surface which may provide more repeatable hair smoothing. The width of the air outlet and/or the air inlet may be in the region of 45 - 70 mm.

The air outlet may be defined in a housing surrounding the curved surface. The air outlet may be upstanding from the air inlet. A base of the outlet may be flush with the curved surface.

The air inlet may comprise a plurality of apertures disposed in the curved surface. Airflow travelling across the curved surface from the air outlet may thus be drawn into the air inlet. Providing a plurality of apertures may help maintain inlet airflow velocity. That is, a single aperture with a relatively large area has a low inlet velocity, whereas a plurality of apertures distributed across an equivalent relatively large area has a lower overall area than the single aperture, resulting in a greater inlet velocity at each aperture, and hence more suction force for a given flowrate. Providing a plurality of apertures, as opposed to a single, larger aperture, may also help to prevent hair from passing through the air inlet towards the airflow generator whilst still permitting sufficient airflow to be drawn into the air inlet.

The apertures may be distributed across the width of the curved surface. This may also provide relatively constant suction force across the width of the curved surface.

The haircare appliance may comprise a filter between the air inlet and the airflow generator.

The curved surface may extend beyond the air inlet. This may help in drawing hair towards the curved surface over a greater arc length, which may improve the smoothing performance of the haircare appliance.

A radius of curvature of a region of the curved surface beyond the air inlet may be different to a radius of curvature of a region of the curved surface between the air outlet and the air inlet. The radius of curvature may be tailored to determine the behaviour of hair being styled during use of the haircare appliance. For example, the radius of curvature of the region beyond the air inlet may determine at what position along the curved surface airflow detaches from the curved surface.

The haircare appliance may comprise a pair of guide walls for directing airflow along the curved surface, the pair of guide walls at opposing sides of the curved surface and upstanding from the curved surface. By providing a pair of guide walls extending outwardly from the curved surface ambient air may be inhibited from impacting on a region of negative pressure generated by airflow flowing along the curved surface in use, and may result in increased attraction of hair toward the curved surface and thus better smoothing performance compared to, for example, a similar arrangement that does not utilise guide walls.

A spacing between the guide walls may correspond substantially to a length of the air outlet and/or the air inlet.

A height of the guide walls may decrease in a direction away from the air outlet. By reducing a height of the guide walls in a direction away from the air outlet less material may be required to form the guide walls than, for example, guide walls of a constant height. The pair of guide walls may comprise a height that gradually decreases in a direction away from the air outlet, for example such that there are no step-changes in height.

The airflow generator is configured to generate airflow at a flow rate in the region of 3 L/s to 10 L/s. Such an airflow rate may be particularly effective in generating an airflow along the curved surface that results in a first force that is sufficient to attract relatively long hair toward the first surface whilst also generating a second force to push relatively short hair away from the curved surface.

The airflow generator may be configured to generate airflow at a flow rate in the region of 4 L/s to 7 L/s.

The airflow generator may draw power in the region of 30 W to 90 W. This may allow the haircare appliance to be battery-powered rather than mains powered.

The airflow generator may comprise a radial or mixed flow impeller. Such an impeller may increase pressure in the airflow generator so that the airflow generator may operate at a lower rotational speed than an airflow generator that does not comprise a radial or mixed flow impeller to provide the same airflow output. Emitting airflow from the airflow generator in a radial direction may alter airflow direction without the need for additional ducting between the airflow generator and the air inlet and the air outlet, which may allow for a more compact arrangement.

The haircare appliance may comprise a battery for powering the airflow generator. The haircare appliance may thus be portable, such that hair can be styled without the need for a plug socket. Hair may be styled using the haircare appliance without being plugged into mains power. The haircare appliance may thus be used whilst on-the-go.

The battery may comprise lithium-ion cells. Lithium-ion cells may provide a suitably sized solution for powering the airflow generator. With lithium-ion cells, the haircare appliance may be charged with a common LISB-C mobile phone battery charger for convenient charging, for example while travelling. For example, the battery may comprise a 18650 cell or 21700 cell.

The haircare appliance may comprise a handle unit and an attachment releasably attachable to the handle unit, the attachment comprising the air inlet, air outlet, airflow generator and curved surface. Providing a removable attachment may allow the functionality of the attachment described herein to be selectively provided by a user.

The battery may be comprised in the handle unit.

According to a second aspect of the present invention there is provided an attachment for a haircare appliance, the attachment comprising: an air inlet; an air outlet; an airflow generator for generating an airflow from the air inlet to the air outlet; and a curved surface adjacent to and downstream of the air outlet, wherein: the attachment is configured such that airflow emitted from the air outlet generates a first force to attract hair toward the curved surface, and a second force to push hair away from the curved surface; the curved surface is between the air outlet the air inlet is; and the air inlet is configured to receive airflow emitted from the air outlet.

Optional features of aspects of the present invention may be equally applied to other aspects of the present invention, where appropriate.

Brief Description of the Drawings

Figure 1 is a schematic view illustrating a haircare appliance according to an example;

Figure 2 is a is a schematic view illustrating forces created by airflow through the haircare appliance of Figure 1 ;

Figure 3 is a front view of a head unit of the haircare appliance of Figure 1 ;

Figure 4 is a schematic cross-sectional side view of the head unit of Figure 3; and

Figure 5 is a schematic view illustrating a second haircare appliance according to an example.

Detailed Description of the Invention

A haircare appliance according to the present invention, generally designated 10, is shown schematically in Figure 1 . The haircare appliance 10 comprises a handle 12 and a styling body 100 attached to the handle 12. In this example, the styling body 100 is fixedly attached to the handle 12 and the haircare appliance 10 is a single-piece unit. In other examples, the styling body 100 is releasably attached to the handle 12 and can thus be selectively attached to the handle 12, as denoted schematically in Figure 1 by the double-ended arrow between the handle 12 and the styling body 100.

The styling body 100 comprises a housing 110 that defines an inner chamber 111 of the styling body 100, an air inlet 102, air outlet 104, a curved surface 108 and a pair of guide walls 120 disposed on opposing edges of the curved surface 108. An airflow generator 106 is housed in the inner chamber 111 and generates airflow at a flow rate of around 6 L/s. The airflow generator 106 comprises a radial impeller.

A first rectangular slot in the housing 1 10 defines the air outlet 104. The radial impeller is in fluid communication with an outlet duct 114 that extends internally within the housing 110 from an outlet of the airflow generator 106 to the air outlet 104. The air outlet 104 is upstanding from the curved surface 108, and the first rectangular slot is defined by the curved surface 108, the guide walls 120, and an upper wall 105 of the housing 110.

A second rectangular slot in the housing defines an air inlet 102. An inlet duct 112 extends internally within the housing 110 from the air inlet 102 to an inlet of the airflow generator 106. A filter 113 is positioned in the inlet duct 112.

The curved surface 108 is positioned on an outer surface of the housing 110 adjacent to and downstream of the air outlet 104. The curved surface 108 extends from the air outlet 104, towards and beyond the air inlet 102. In this example, the second rectangular slot defining the air inlet 102 is a slot in the curved surface 108.

The curved surface 108 subtends an angle of around 80 degrees from the air outlet 104 to the air inlet 102 and has a radius of curvature of around 40 mm. The curved surface 108 extends beyond the air inlet 102, as best shown in Figure 4. A region 109 of the curved surface 108 beyond the air inlet 102 is flat. The air outlet 104 and the air inlet 102 extend across more than 90% of a width W (as denoted in Figure 3) of the curved surface 108. The air outlet 104 and the air inlet 102 each have a fixed cross-sectional area, length and width. The cross- sectional area of the air inlet 102 is around two times greater than a cross- sectional area of the air outlet 104.

Three ribs 103 extend across the width of the air inlet 102. In other examples, the air inlet 102 may additionally or alternatively comprise a mesh or other suitable air-porous barrier.

The pair of guide walls 120 are for directing airflow along the curved surface 108. The guide walls 120 are upstanding from the curved surface 108. The guide walls 120 decrease in height along the curved surface 108. Adjacent to the air outlet 104, the guide walls 120 have a height that is greater than a height of the air outlet 104. Adjacent to the air inlet 102, the guide walls 120 have a height that tends toward zero.

Although not present in this example, in other examples a heater for heating airflow generated by the airflow generator 106 is located in the inner chamber 111.

The handle 12 comprises a tubular housing 14 which houses a lithium-ion battery 16 (shown in dashed lines in Figure 1 to denote that the battery 16 is housed within the housing 14) and a control unit (not shown). A user interface 18 is located on an outer surface of the housing 14 and is operable by a user to cause the control unit to control the haircare appliance 10.

The user interface 18 is used to power on and off the haircare appliance 10, to select a flow rate (for example high, medium and low), and to select an airflow temperature (for example hot, medium or cold in examples in which the haircare appliance comprises a heater). In the example of Figure 1 , the user interface comprises a button, but other forms of user interface 18, for example one or more switches, dials or touchscreens, are also envisaged.

The control unit is responsible for controlling the airflow generator 106 in response to inputs from the user interface 18. For example, in response to inputs from the user interface 18, the control module may control the power or the speed of the airflow generator 106 in order to adjust the airflow rate of the airflow. The airflow generator 106 draws power from the battery 16 at around 80 W.

In response to a user input at the user interface 18 to power on the airflow generator 106, airflow generated by the airflow generator 106 is emitted from the air outlet 104, travels across the curved surface 108 and is drawn into the air inlet 102. The airflow is thus recirculated through and around the styling body 100, as denoted by the dashed arrows in Figure 4.

Providing the curved surface 108 adjacent to and downstream of the air outlet 104 can cause airflow to attach to the curved surface 108 via the Coanda effect. With reference to the schematic illustration of the interaction of forces shown in Figure 2 and the cross-sectional side view shown in Figure 4, when a tress of hair 1 is brought into the vicinity of the styling body 100, long hairs 2 of the tress are attracted to, and at least partially wrapped about, the curved surface 108 by a force F_PULL, as a result of a negative pressure region generated by the airflow over the curved surface 108. However, the pressure gradient across the tress 1 also results in a force, F_PUSH, which causes some airflow to pass directly through the tress 1 . Due to the location of this force relative to the curved surface 108 and the rest of the tress 1 , shorter hairs 3 are only held loosely at this point compared to longer hairs 3 which are held in place on the curved surface 108. The shorter hairs 3 are blown through the tress 1 toward a user’s head, whilst the longer hairs 2 remain in place on the outside of the tress 1 , i.e., the portion of the tress 1 facing away from the user’s head. This provides a smooth finish for hair following interaction with the haircare appliance 10.

To generate sufficient forces F_PULL, F_PUSH to effectively style hair to provide a smooth finish requires relative high airflow velocity at the air outlet 104 and thus a relatively large amount of power. In order to increase the force F_PULL towards the curved surface without increasing the airflow velocity at the air outlet 104, the curved surface 108 is between the air outlet 104 and the air inlet 102, and the air inlet 104 is configured to receive airflow emitted from the air outlet 104 after the airflow has passed over the curved surface 108.

Suction generated at the air inlet 102 by the airflow generator 106 draws the tress 1 toward the air inlet 102. In turn, the longer hairs 2 are held on the curved surface 108 over a longer distance, as best shown in Figure 4, compared to an appliance in which the air inlet is located elsewhere. Accordingly, the styling body 100 may provide enhanced smoothing performance for the same power input, or may be operable at a lower power input to provide comparable smoothing performance.

As mentioned above, the pair of guide walls 120 extend along opposing edges of the curved surface 108. This effectively creates an airflow channel, with the pair of guide walls 120 acting as walls of the channel, and the curved surface 108 acting as a bed of the channel. The guide walls 120 inhibit ambient air from interacting with airflow flowing along the curved surface 108 in use, which may maintain the negative pressure region created by airflow flowing along the curved surface 108.

The flat region 109 of the curved surface 108 helps to separate longer hairs from the styling body 100 downstream of the air inlet 102 and the guide walls 120.

Although described herein as embodiments in which the haircare appliance comprises a handle and a styling body, embodiments are also envisaged in which the handle is omitted, and the battery 16, control unit and user interface 18 are comprised in the styling body, as shown in the haircare appliance 20 shown in Figure 5. In such embodiments, a user grips an outer surface of the housing 110 to perform a hair styling operation, rather than gripping a handle.

Although described herein as comprising a battery, in other embodiments the haircare appliance may be mains powered.