Patent Description:
A hair straightener utilises heated plates attached to pivoted arms which can be held, by a user, in a closed position with a tress of hair clamped between the heated plates. The tress of hair can be styled into a changed shape once the hair is heated above a transition temperature.

Both corded and cordless hair styling appliances are known, including cordless hair straighteners having a battery pack which can be recharged by the user. A typical cordless hair straightener may have a battery pack disposed in one arm, thereby creating an imbalance in the weight distribution of the hair straightener. Styling hair with hair straighteners requires a repetitive user action, and an imbalance in the weight distribution of the appliance can lead to discomfort in the hand of the user. It is therefore desirable to provide an improved hair styling apparatus.

Some background information may be found in <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>.

Embodiments are provided in accordance with the appended claims.

The present invention provides a hair styling apparatus comprising a first arm and a second arm coupled together at a hinge end thereof to allow the first arm and the second arm to be moveable between a closed position, in which a facing side of the first arm and a facing side of the second arm are adjacent, and an open position, in which the facing side of the first arm and the facing side of the second arm are spaced apart, a central pack disposed between the first arm and the second arm and coupled to the hair styling apparatus at the hinge end; and a biasing means adapted to support the central pack symmetrically between the first arm and the second arm, wherein the biasing means comprises at least two springs, the at least one spring comprises a first spring coupled between the first arm and the central pack, and a second spring coupled between the second arm and the central pack, wherein the first spring and the second spring are symmetrically disposed with respect to a longitudinal central axis of the hair styling apparatus.

Such a symmetrical, balanced arrangement improves the ergonomics of the hair styling apparatus.

In use, an air gap is formed between the first arm and the central pack and also between the second arm and the central pack. Advantageously, each air gap forms thermal insulation between the arms and the central pack, thereby minimizing heat transfer between the user's hands, the central pack and heating means in the arms.

Preferably, the central pack is a power pack, and the power pack comprises at least one cell.

In a preferred embodiment, the central pack comprises a motor and a fan.

The hair styling apparatus may further comprise a cover connected between the first arm and the second arm, wherein the cover is adapted to protect the central pack.

The first spring and the second spring may be coil springs or leaf springs, and may be integrally formed from a metal arm casing structure.

In a preferred embodiment, the at least one spring comprises a torsion spring coupled to a coil spring, wherein the torsion spring may comprise a pivot and a first leg and a second leg attached to the first arm and the second arm, respectively. Further, the coil spring comprises a first end attached to the pivot via a lug, and a second end attached to the central pack.

A simple coil spring has a spring force which increases as the spring is progressively compressed. Advantageously, this arrangement of the torsion spring and the coil spring provides a progressively lower spring force as the styling apparatus arms are moved into the closed position, whilst providing a greater spring force when the styling apparatus arms are open.

Preferably, the hair styling apparatus comprises a cover connected between the first arm and the second arm, wherein the cover is adapted to protect the central pack. More preferably, the cover is attached to the torsion spring, thereby enabling the cover to retract when the first arm and the second arm are in the closed position.

In a preferred embodiment the first arm and the second arm are symmetrical in structure, and are substantially identical in weight, and further the central pack is substantially symmetrical in structure about the longitudinal central axis of the hair styling apparatus.

Also described herein is a hair styling apparatus comprising a first arm and a second arm coupled together at a hinge end thereof to allow the first arm and the second arm to be moveable between a closed position, in which a facing side of the first arm and a facing side of the second arm are adjacent, and an open position, in which the facing side of the first arm and the facing side of the second arm are spaced apart, a power pack disposed between the first arm and the second arm and coupled to the hair styling apparatus at the hinge end, wherein the power pack comprises a plurality of cells.

Preferably, the battery pack comprises four cells, wherein the four cells are interconnected and comprise four cells connected in series, or two cells connected in parallel and two cells connected in series.

In a preferred embodiment, each cell is a secondary cell. Each cell may be an elongate lithium-ion cell, having an electrical contact at each end. Preferably, each electrical contact is connected to a battery tab. Preferably, the battery tab comprises a yield line. In a preferred embodiment, the battery tab connects two adjacent electrical contacts and has a folded arrangement, such that the battery tab is folded through <NUM> degrees. Further, the battery tab may have a yield line and a slot extending from an edge of the battery tab such that the slot traverses the yield line and divides in two parts at that junction, thereby forming a Y-shaped slot.

It is preferred that each electrical contact is connected to a battery tab by resistance welding. Preferably, the power pack comprises a sleeve adapted to receive a frame, such that the frame supports the four cells. Advantageously, the sleeve minimizes ingress of debris in proximity to the cells and the associated interconnections. Also, the sleeve may function to protect the cells, interconnections and PCBs if the hair styling apparatus were to suffer an impact. Further, the sleeve provides structural rigidity to the hair styling apparatus.

Also described herein is a battery tab for connection to a cell contact, the battery tab comprising a slot, wherein a first portion of the slot extends in a straight line from an edge of the battery tab, and then divides in two parts, thereby forming a Y-shaped slot. Advantageously, such a Y-shaped slot avoids a major part of the slot being coterminous with a battery tab yield line.

Preferably, the first portion extends midway between a first pair of projections and a second pair of projections. The projections may be welded to the cell terminal by resistance welding.

Also described herein is a hair styling apparatus comprising a first arm and a second arm coupled together at a hinge end thereof to allow the first arm and the second arm to be moveable between a closed position, in which a facing side of the first arm and a facing side of the second arm are adjacent, and an open position, in which the facing side of the first arm and the facing side of the second arm are spaced apart, a power pack disposed between the first arm and the second arm and coupled to the hair styling apparatus at the hinge end, and a wire harness for coupling the power pack to a heater arrangement, wherein the wire harness has a first portion extending within the power pack and a second portion extending within the first or second arm.

The term "harness" refers to an arrangement of wires once they are assembled within a product.

Preferably, the wire harness has a point of inflection between the first portion and the second portion, and the point of inflection is in proximity to the hinge. It is preferred that the first portion of the wire harness is coupled to the power pack. Preferably, the second portion of the wire harness is coupled to the heater arrangement.

In a preferred embodiment, the first and second portions of the wire harness are disposed parallel to one another when the first and second arms are in a closed position. Further, the first and second portions of the wire harness may be disposed at an angle to one another when the first and second arms are in an open position. Preferably, the power pack is adapted to receive the first portion of the wire harness, and an inner surface of at least one of the first and second arms is adapted to receive the second portion the wire harness.

In a preferred embodiment, the heater arrangement is disposed within at least one of the first and second arms. Each of the first and second arms may comprise one wire harness or each of the first and second arms may comprise two wire harnesses. Preferably, each of the first and second arms carry the second portion of a wire harness carrying a positive charge and the second portion of a wire harness carrying a negative charge.

The four power harnesses are routed indirectly between the power source and the heater assembly. This indirect routing is achieved via articulating each harness at the hinge end of the hair styling apparatus. Advantageously, this articulation of the harnesses minimises wire fatigue and avoids any disconnect in the power route between the power source and the heaters.

Also described herein is a hair styling apparatus comprising a first arm and a second arm coupled together at a hinge end thereof to allow the first arm and the second arm to be moveable between a closed position, in which a facing side of the first arm and a facing side of the second arm are adjacent, and an open position, in which the facing side of the first arm and the facing side of the second arm are spaced apart, a central pack disposed between the first arm and the second arm and coupled to the hair styling apparatus at the hinge end, and a locking means disposed within the central pack; wherein the locking means comprises an elongate lock arm disposed lengthwise within the central pack.

Preferably, the locking means further comprises a lock bar disposed symmetrically at a first end of the lock arm. Preferably, the lock arm together with the lock bar has a T-shape form. It is preferred that the locking means is adapted to move relative to the central pack and between a first position and a second position; and wherein a user interface lock button on an external surface of the central pack is connected to the locking means and is adapted to move the locking means between the first position and the second position.

Preferably, the locking means further comprises an actuator movably attached to the central pack, wherein the actuator is connected to a biasing means and the actuator is biased in an extended position.

The actuator may be adapted to be moved into a contracted position when at least one of the first arm and the second arm is in a closed position. Preferably, the actuator is pushed into the contracted position by a protrusion from at least one of the first arm and the second arm. It is preferred that the locking means is movable between the first position and the second position when the actuator is in the contracted position, and that the locking means is immovable when the actuator is in the extended position.

Preferably, the biasing means is a spring, and more preferably, a coil spring.

A catch feature is integral to an inner surface of each of the first arm and the second arm. The catch features are formed to engage with the lock bar. Therefore, when the lock bar can be moved into the lock position, then the first and second arms are simultaneously and symmetrically locked to the central pack.

In a preferred embodiment, the central pack is a power pack. The central pack may comprise at least one frame and said frame is adapted to support the locking means and at least one cell and a user interface PCB. It is preferred that the lock arm is connected to the frame by a torsion spring.

In order that the present invention may be more readily understood, an embodiment of the invention will now be described, by way of example, and with reference to the accompanying drawings, in which:.

A hair styling apparatus <NUM>, as shown in <FIG>, comprises a first arm <NUM>, a second arm <NUM> and a central pack <NUM>, which are pivotally joined together at one end by a hinge <NUM>. The hair styling apparatus <NUM> comprises a handle section <NUM> towards the hinge end of the arms and a hair contacting section <NUM> towards the distal end of the arms. The hair contacting section <NUM> comprises a plate <NUM>, <NUM> arranged on at least one of the facing surfaces of the arms. The plate <NUM>, <NUM> can be a flexible or non-flexible hair contacting plate, which may have an increased temperature when the hair straightening apparatus <NUM> is in use. When the hair straightening apparatus <NUM> is not in use, the plate will generally be at the ambient temperature.

A longitudinal axis, x, is indicated in <FIG>, which extends lengthways through the centre of the hair styling apparatus <NUM>.

In a preferred embodiment, the hair styling apparatus <NUM> is a battery operated hair straightener, wherein the hair contacting section <NUM> comprises a heated metal plate. In such an embodiment, an electrical connector <NUM> is located at the hinge end of the hair styling apparatus <NUM>, and the central pack <NUM> is a battery pack assembly.

With reference to <FIG>, a battery pack sleeve <NUM> is generally tubular and provides a protective casing for a battery pack. The battery pack sleeve <NUM> has a first end <NUM> which is substantially closed and located in proximity to the hinge, and a second end <NUM> which is open and located in proximity to the heated plates. The battery pack sleeve <NUM> has a first harness guide <NUM> formed in the battery pack sleeve <NUM> and extending between the first end <NUM> and the second end <NUM>. A second harness guide <NUM> also extends along the battery pack sleeve <NUM>, parallel to the first harness guide <NUM>. The battery pack sleeve <NUM> has a third harness guide <NUM> and a fourth harness guide <NUM> extending along an inner face of the battery pack sleeve <NUM> between the first end <NUM> and the second end <NUM>, and parallel to the third harness guide.

An aperture <NUM> is located on the second harness guide <NUM> towards the first end <NUM> of the battery pack sleeve <NUM>. Similar apertures are positioned on each harness guide towards the first end of the battery pack sleeve but cannot be seen in <FIG>. A hinge screw hole <NUM> is formed on each of opposing sides of the first end of the battery pack sleeve <NUM>. Several rounded cutouts <NUM> are located in a face of the battery pack sleeve <NUM> between the second and third harness guides.

An arrangement of four rechargeable cylindrical battery cells are shown in <FIG>. An end face of a first cell <NUM> is aligned with an end face of a second cell <NUM>, and electrically joined in series. An end face of a third cell <NUM> is aligned with an end face of a fourth cell <NUM>, and electrically joined in series. The first and second cells <NUM>, <NUM> are joined in parallel with the third and fourth cells <NUM>, <NUM>. A foam ring <NUM>, <NUM>, <NUM>, <NUM> having an outer diameter similar to each cell is positioned at an outer end face of each cell <NUM>, <NUM>, <NUM>, <NUM>. Such foam rings function to absorb a shock to the battery pack <NUM> when the hair styling apparatus <NUM> is in use. A fish paper ring <NUM> having an outer diameter similar to each cell is positioned between an end face of the first cell <NUM> and the second cell <NUM> and a further fish paper ring <NUM> is positioned between the third cell <NUM> and the fourth cell <NUM>.

Each cell is a high power lithium-ion cell of around <NUM>. 8V and has a relatively high capacity of around 1400mAh. Each cell has a maximum charge of approximately <NUM>. 5A and a maximum discharge of approximately 20A.

A first cell tab <NUM> is connected to a positive terminal of the first cell <NUM>. A positive terminal of the second cell <NUM> is connected to a negative terminal of the first cell via a second interconnect tab <NUM>. A negative terminal of the second cell is connected to a positive terminal of the third cell <NUM> via a third interconnect tab <NUM>. A positive terminal of the fourth cell <NUM> is connected to a negative terminal of the third cell <NUM> via a fourth interconnect tab <NUM>. A fifth cell tab <NUM> is connected to a negative terminal of the fourth cell <NUM>.

Each connection in the illustrated embodiment is a welded connection realised by resistance welding. Alternatively, the connection between the battery pack tabs and the battery terminals may be realised by any suitable form of weld or join or solder.

<FIG> illustrates the connection between the first cell <NUM> and the second cell <NUM>, and also between the third cell <NUM> and the fourth cell <NUM>. The interconnect tab <NUM>, <NUM> forms a U-shaped bend between the connected cells. Advantageously, this shape provides some elastic movement between the cells, as well as minimising space requirements for four connected cells. The interconnect tab <NUM> further comprises a protrusion <NUM> which, in the assembled apparatus, is disposed through a second frame part (illustrated in <FIG>) and soldered to a battery management system PCB.

In <FIG>, a first tab layout is illustrated having a straight slot <NUM> with two welding dimples <NUM> on either side of the straight slot <NUM>. A first yield line <NUM> extends from a first edge of the tab to a second, opposite, edge of the tab, and traverses the straight slot <NUM>. A second yield line <NUM> extends from the first edge of the tab to the second, opposite, edge of the tab, adjacent the end of the straight slot <NUM>. (As shown in <FIG>, a yield line may allow a flection of the tab in either fold direction.

In order to optimise the weld current, a longer slot length is required. However, whilst the second tab layout shown in <FIG>, increases slot length by having a T-shaped slot <NUM> with two welding dimples <NUM> on either side of the slot. Such a T-shape introduces a potential structural weakness where the slot coincides with a yield line. Therefore, in <FIG>, a third tab layout is illustrated having a Y-shaped slot <NUM> with two welding dimples 96on either side of the slot. A first yield line <NUM> extends from a first edge of the tab to a second, opposite, edge of the tab, and traverses a mid-point of the Y-shaped slot <NUM>. A second yield line <NUM> extends from the first edge of the tab to the second, opposite, edge of the tab, adjacent the ends of the Y-shaped slot <NUM>.

Advantage is obtained from a Y-shaped slot, as a consequence of the greater total slot length in comparison with the straight slot of <FIG>. Specifically, a greater total slot length optimises the weld current during the resistive welding process, thereby increasing the weld temperature at the base of each dimple.

The battery pack tabs are preferably comprised of a copper alloy having a thickness of approximately <NUM>. The battery pack tabs may have a tin plating of approximately <NUM> microns thickness.

The arrangement of four cells is secured within a frame comprising a first frame part <NUM> and a second frame part <NUM>, as shown in <FIG>. An inner face of each of the first frame part <NUM> and the second frame part <NUM> fits and engages the arrangement of four cells <NUM>, <NUM>, <NUM>, <NUM>. An outer face of the first frame part <NUM> is arranged to support a user interface PCB and an outer face of the second frame part <NUM> is arranged to support a battery management system PCB. The first and second frame parts also provide stability for the combined arrangement of the cells and PCBs. Also, the first and second frame parts house the cells and PCBs in close proximity, thereby minimising the combined volume of these parts and consequently the overall circumference of the hair styling apparatus. Further, an OLED and a speaker (not shown) are mounted on the user interface PCB, and the assembled hair styling apparatus <NUM> is arranged such a sound chamber cavity is formed adjacent to the speaker. The first frame part <NUM> and the second frame part <NUM> comprise snap-fit structures as an engagement mechanism to fix them together.

In such a hair styling apparatus <NUM>, there is a need to route the power from the central battery pack <NUM> to the heater assembly in each arm. However, when the arms are in an open position, there is gap between the battery pack and the arms at the distal end of the battery pack. An electrical join across this gap would potentially be a high resistance connection which could cause heat to develop. Therefore, an alternative scheme for transferring power from the battery pack to the at least one heater assembly is desirable.

In <FIG>, a route of two power harnesses is schematically illustrated in relation to the arms of the hair styling apparatus. The route of each power harness runs generally parallel to the longitudinal axis, x, both on a path towards the hinge end and also, after an articulation, on a return path towards a distal end. The path towards the hinge is routed along an inner surface of the battery pack sleeve <NUM> and the return path towards the distal end of the apparatus is routed through the first or second arm <NUM>, <NUM>, respectively.

A first end of each power harness is connected to the battery management system PCB. This connection may be realised by a soldered join. A second end of each power harness is connected to a heater assembly located within each arm of the hair styling apparatus. This connection may be a wire to wire interconnect, realised by a crimp terminal.

Each power harness is preferably a <NUM> AWG wire having PTFE insulation. PTFE insulation is highly effective and consequently a relatively thin layer of PTFE around the central wire strands is required. This allows each power harness to have a minimised diameter and is therefore advantageous in minimising the volume occupied by the four power harnesses in the hair styling apparatus.

The cross-sectional view through the handle section, shown in <FIG>, shows four power harnesses, each running towards the hinge end (denoted as a) and returning towards the distal end (denoted as b). In use, a first harness <NUM> carries a negative current, a second harness <NUM> carries a positive current, a third harness <NUM> carries a negative current, and a fourth harness <NUM> carries a positive current. It should be noted that the first end of both the second and third harnesses are routed across the battery pack to the battery management system PCB via an over harness chassis (not shown) which is integral to the battery pack <NUM>.

The first cell <NUM> is located adjacent to the forth cell <NUM>, and the first and forth cell are positioned centrally along a y-axis of the apparatus. The battery pack sleeve <NUM> surrounds both cells <NUM>, <NUM> with a small tolerance gap between the sleeve and the cells to allow for manufacturing tolerances and possible thermal expansion of the components. An interference rib <NUM>, <NUM>, <NUM>, <NUM> is located between the external surface of the battery pack sleeve <NUM> and an inner surface of one of the arm shells <NUM>, <NUM>, adj acent to each power harness. The interference ribs <NUM>, <NUM>, <NUM>, <NUM> immobilise the battery pack within the battery sleeve.

<FIG> illustrates the symmetry of the handle section of the hair styling apparatus with respect to the y-axis and the z-axis. A first hinge screw <NUM> and a second hinge screw <NUM> are positioned symmetrically at each side of the hinge end of the hair styling apparatus. The first frame part <NUM> and the second frame part <NUM> are also symmetrically arranged with respect to the y-axis and the z-axis.

<FIG> illustrate the form and function of a locking mechanism which enables the arms of the styling apparatus to be fixed in a closed position by a user-actuated sliding button. Whilst the illustrated embodiment comprises a central pack which is a battery pack, the central pack may alternatively be a motor pack providing airflow or vibrational movement to the styling apparatus arms, or a power pack providing any electromagnetic radiation to the styling apparatus arms.

A lock arm <NUM> extends longitudinally within the handle section <NUM> of the hair styling apparatus <NUM> and is located between the arm shells <NUM>, <NUM> and the first frame part <NUM>. The lock arm <NUM> has a T-shape form and comprises a shaft <NUM> with a slider cap receiver <NUM> at a first end <NUM>, and a perpendicular lock bar <NUM> at the second end <NUM>. The lock bar <NUM> has a lock bar block <NUM>, <NUM> at each end, which, in the embodiment illustrated, is a triangular prism. The lock arm <NUM> is positioned with the first end <NUM> in proximity to the hinge end <NUM> of the styling apparatus.

The lock arm <NUM> further comprises a lock arm boss <NUM> protruding from the lock arm <NUM> on the side adjacent the first and second arm shells <NUM>, <NUM>. The lock arm boss <NUM> passes through a first leg <NUM> of a torsion spring <NUM> and a first frame boss <NUM> passes through a second leg <NUM> of the torsion spring <NUM> (shown in <FIG>). The torsion spring <NUM> functions as a biasing mechanism move the lock arm towards the hinge end <NUM> of the styling apparatus <NUM>.

A sleeve cap <NUM> of a battery pack sleeve <NUM>, a spring housing <NUM>, a lock out actuator <NUM> and a lock out spring <NUM> are seen separately in <FIG>, and in assembled position in a transparent illustration of the sleeve cap <NUM> in <FIG>. A first end of the spring <NUM> is attached to a foot <NUM> of the lock out actuator <NUM> and a second end of the spring <NUM> is attached to a stabilising base <NUM> at a mid-point within the spring housing <NUM>. In both an extended state and a compressed state of the spring <NUM>, the actuator foot <NUM> is positioned within the spring housing <NUM>. The spring housing is fixed to the sleeve cap <NUM> and the sleeve cap comprises longitudinal engaging protrusions <NUM> which have a friction fit within the battery pack sleeve <NUM>, thereby fixing the position of the spring housing <NUM> relative to the first and second frame parts <NUM>, <NUM>.

In use, when the styling apparatus arms <NUM>, <NUM> are arranged in an open position, then the lock out spring <NUM> is in the extended state within the spring housing <NUM>. Consequently, the lock out actuator <NUM> is in an extended position, as seen in <FIG>. In this position, the lock out actuator <NUM> abuts the lock bar block <NUM>, as shown in <FIG>, thereby fixing the lock arm <NUM> in position and rendering the lock button <NUM> immovable.

When the styling apparatus arms <NUM>, <NUM> are moved from the open position towards the closed position, a protrusion (not shown) on an inner surface of the first arm comes into contact with the lock out actuator and then gradually pushes the lock out actuator <NUM> a distance p towards the second arm. When the styling apparatus arms <NUM>, <NUM> are in a fully closed position, then the lock out spring <NUM> is in the compressed state within the spring housing <NUM> and the lock out actuator is in a retracted position, as seen in <FIG>. In this lock position, the lock out actuator <NUM> no longer abuts the lock bar block <NUM> thereby allowing the lock arm <NUM> to move distance m, towards the hinge end <NUM> of the styling apparatus <NUM> when the user actuates the lock button <NUM>, as shown in <FIG>.

A catch feature (not shown) is integral to an inner surface of each of the first arm shell <NUM> and the second arm shell <NUM>. The catch features are formed to engage with the lock bar <NUM>. Therefore, when the lock arm <NUM> can be moved into the lock position, then the first and second arms <NUM>, <NUM> are simultaneously and symmetrically locked to the central pack <NUM>.

The general structure of the hair styling apparatus, as shown schematically in <FIG>, comprises a first arm <NUM>, a second arm <NUM> and a central pack <NUM>. Where the first and second arms are substantially identical in form and weight, and the central pack has a generally constant weight distribution along its length, then the centre of mass will be located within the handle section. This increases ergonomic comfort for the user, because a balanced apparatus may minimise a user's hand and arm strain, and also be perceived as a lighter in weight in comparison to an unbalanced apparatus. Importantly, the present hair styling apparatus has a spring mechanism for elastically opening and closing the arms, which maintains symmetry of the styling apparatus about the x-axis during the opening action and also when the arms are fully open. This provides significant ergonomic benefit for the user, as the styling apparatus feels balanced in use.

<FIG> and <FIG> schematically illustrate options for elastically securing the arms and central pack to one another, enabling the arms to be biased into the open position and also smoothly closeable by the user.

<FIG> illustrates a first coil spring <NUM> attached between an internal surface of the first arm <NUM> and an adjacent surface of the central pack <NUM> and a second coil spring <NUM> attached between an internal surface of the second arm <NUM> and the central pack <NUM>. This symmetrical arrangement is mechanically simple and reliable whilst maintaining a balanced weight distribution within the styling apparatus. Alternatively or additionally, a third and fourth coil spring <NUM>, <NUM> can be positioned in closer proximity to the hinge end <NUM> of the styling apparatus <NUM>. Such an alternative arrangement of the coil springs is also shown in <FIG>.

<FIG> schematically illustrates a first leaf spring <NUM> positioned between an internal surface of the first arm <NUM> and an adjacent surface of the central pack <NUM> and a second leaf spring <NUM> positioned between an internal surface of the second arm <NUM> and the central pack <NUM>. The first and second leaf springs <NUM>, <NUM> are formed out of metal and may be flat or cylindrical in cross-section and each of the first and second leaf springs may be composed of one or more leaf springs. Again, this symmetrical arrangement is mechanically simple and reliable whilst maintaining a balanced weight distribution within the styling apparatus. In a preferred embodiment, the first and second arms comprise a metal arm structure <NUM>, <NUM> and the leaf springs <NUM>, <NUM> are integrally formed with the metal arm structure. Such a metal arm structure is beneficial with respect to the rigidity of the apparatus and an outermost surface of the metal arm structure is covered by a plastics layer.

A further spring arrangement is illustrated schematically in <FIG>, and may be utilised alone or in combination with the spring arrangement described with respect to <FIG>. As illustrated in <FIG>, a torsion spring arrangement <NUM> comprises a lug <NUM> attached to a torsion spring <NUM> at the central pivot point <NUM> of the torsion spring. The lug <NUM> comprises a shoulder <NUM> having a greater diameter than the main cylindrical portion of the lug <NUM>. A folding cover <NUM> is illustrated in <FIG>, and comprises a first board portion <NUM> and a second board portion <NUM>, together with the torsion spring arrangement <NUM>. The first and second board portions <NUM>, <NUM> share a common hinged edge held together and pivoted by a central pin <NUM>. A first pin <NUM> passes through a tubular passage <NUM> at an outer edge of the first board portion <NUM>, and a second pin <NUM> passes through a tubular passage <NUM> at an outer edge of the second board portion <NUM>. The torsion spring arrangement <NUM> is attached to the folding cover <NUM> by fixing the pivot point <NUM> of the torsion spring arrangement <NUM> over the central pin <NUM>, and fixing the first and second legs of the torsion spring arrangement <NUM> over the first and second pins <NUM>, <NUM>, respectively.

With reference to <FIG>, the folding cover <NUM> is located in between the first and second arms <NUM>, <NUM> of the hair styling apparatus <NUM>, and at the transition between the hair contacting section <NUM> and the handle section <NUM>. Both ends of the first pin <NUM> are received into receiving apertures on the first arm <NUM>, and both ends of the second pin <NUM> are received into receiving apertures on the second arm <NUM>. The central pack <NUM> comprises a receptacle <NUM> positioned to receive the lug <NUM> of the torsion spring arrangement when the first and second arms <NUM>, <NUM> of the styling apparatus are closed, as illustrated in <FIG>. When the first and second arms of the styling apparatus are moved to an open position, the lug <NUM> of the torsion spring arrangement <NUM> is lifted out of the receptacle <NUM> by the movement of the folding cover <NUM> and connected torsion spring <NUM>.

A coil spring <NUM> is located between the receptacle <NUM> and the lug, in order to moderate the relative movement of the lug <NUM> with respect to the receptacle <NUM>. The coil spring <NUM> may be connected to the lug <NUM>, or within the receptacle <NUM>, or both. A first end <NUM> of the coil spring abuts a base of the receptacle and a second end <NUM> of the coil spring <NUM> abuts the shoulder <NUM> of the lug <NUM>. Advantageously, this arrangement of the torsion spring <NUM> and the coil spring <NUM> provides a progressively lower spring force as the arms of the styling apparatus are moved into the closed position (minimal angular displacement), whilst providing a progressively greater spring force as the styling apparatus arms are moved into the open position (maximal angular displacement), as shown schematically by data line B in <FIG>. Thus, although the styling apparatus arms are biased into the open position, the user can easily squeeze the arms into the closed position in order to grip the tress of hair.

For comparison, data line A in <FIG> schematically shows the spring characteristic of a typical spring mechanism for which the spring force increases as the arms are moved from the open to the closed position. Therefore, greatest effort is required by a user to squeeze the styling apparatus arms together in order to grip the hair between the arms. Repetition of this action could result in discomfort for the user.

Advantageously, the folding cover <NUM> protects the central pack <NUM> from ingress of debris, such as single hairs or chemical hair products. The folding cover additionally functions to maintain the parallel arrangement and smooth functioning of the styling apparatus arms, by impeding accidental torsional movement of between the styling apparatus arms. In a further embodiment, a second torsion spring arrangement could be included at the other edge of the folding cover in order to increase the symmetry and balance of the hair styling apparatus, but mainly to further avoid the possibility of accidental torsional movement between the arms of the styling apparatus. In an alternative embodiment, the folding cover may comprise a flexible material without a central hinged section.

Each of the spring arrangements described in relation to <FIG> and <FIG> may be used alone or in combination with springs at the hinge end of the styling apparatus. The springs at the hinge of the styling apparatus may be torsion springs or C-cup springs, and the hinge arrangement may be exposed on an external face of the styling apparatus or concealed under the arm structure.

It will be apparent to the skilled person that various alternatives are possible within the scope of the present invention. For example, any number of symmetrically arranged rechargeable cells may be utilised, including a single cell arrangement. The cells may be connected in various electrical arrangements; either in series or in parallel or a combination of both. The battery pack sleeve may comprise an opening at either the hinge end or the distal end, through which the arrangement of cell(s) may be inserted, and a battery sleeve cap is subsequently attached over the opening.

The hair contacting section may comprise a heated plate arranged on at least one of the facing surfaces of the arms. The heated plate may be a regular, non-flexing heated plate or, alternatively, the heated plate may be flexible. In use, the hair contacting surface <NUM> of the heated plate <NUM> may have a temperature between <NUM> and <NUM>, and more preferably between <NUM> and <NUM>. The hair contacting surface, may have a form which is non-rectangular in shape, such as a square, an oval or an irregular form.

With reference to the battery pack arrangement shown in <FIG>, the first frame part and the second frame part may comprise alternative engagement mechanisms, such as interlocking parts, to fix them together. During assembly, the battery pack may be inserted into the battery pack sleeve via an opening at the hinge end or the distal end of the battery pack sleeve.

With reference to <FIG>, the interference ribs secure the battery pack within the battery sleeve and may, alternatively, be integrally moulded as part of the battery pack sleeve or, alternatively, part of the first and second arm shell.

With reference to <FIG>, the lock bar block at the end of the lock bar may have any suitable form. Further, the lock bar may have a lock bar block at only one end in order to allow correct functionality of the locking mechanism. However, a symmetrical lock arm may be preferable to provide a symmetrical weight distribution to ensure smooth functioning of the user interaction slider cap action. The lock arm may be comprised of plastic or metal, such as stainless steel.

A single lock out actuator which abuts one of the two lock bar blocks, has been described herein. However, a second lock out actuator (and associated lock out spring and spring housing), may be employed symmetrically about the z-axis from the lock out actuator. The second lock out actuator would abut a second of the two lock bar blocks. Advantageously, such a second lock out actuator would avoid any asymmetrical or torsional forces being applied to the lock arm.

Claim 1:
A hair styling apparatus (<NUM>) comprising;
a first arm (<NUM>) and a second arm (<NUM>) coupled together at a hinge end thereof to allow the first arm (<NUM>) and the second arm (<NUM>) to be moveable between a closed position, in which a facing side (<NUM>) of the first arm (<NUM>) and a facing side (<NUM>) of the second arm (<NUM>) are adjacent, and an open position, in which the facing side (<NUM>) of the first arm (<NUM>) and the facing side (<NUM>) of the second arm (<NUM>) are spaced apart;
a central pack (<NUM>) disposed between the first arm (<NUM>) and the second arm (<NUM>) and coupled to the hair styling apparatus at the hinge end; and
a biasing means (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) adapted to support the central pack (<NUM>) symmetrically between the first arm (<NUM>) and the second arm (<NUM>), wherein the biasing means (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) comprises at least two springs, the at least two springs comprising a first spring (<NUM>, <NUM>, <NUM>) coupled between the first arm (<NUM>) and the central pack (<NUM>), and a second spring (<NUM>, <NUM>, <NUM>) coupled between the second arm (<NUM>) and the central pack (<NUM>), wherein the first spring and the second spring are symmetrically disposed with respect to a longitudinal central axis of the hair styling apparatus.