Patent Description:
Hair cutting appliances typically comprise a cutting unit, and it is beneficial to enable the cutting unit to be pivotable relative to a handle, in order to be able to follow the contours of a user's skin surface to create optimal contact between the user's skin and the cutting unit, to attain the best cutting performance.

An example of prior art is given by the patent documentation <CIT>.

According to a first specific aspect, there is provided a mounting assembly for a hair cutting appliance, the mounting assembly comprising:
a head comprising a body, extending along an elongate axis, and a driving bridge, the head being configured to receive a cutting unit, wherein the driving bridge is configured to couple to the cutting unit and to reciprocally move relative to the body along the elongate axis;.

One of the base bearing surface or the counterpart bearing surface comprises an inner surface of a slot having a curvature about the fixed rotational axis. The other of the base bearing surface or the counterpart bearing surface comprises an outer surface of a pin which is configured to be received within the slot.

A fixed rotational axis is intended to mean a rotational axis which is stable, and does not move relative to the head or the base. The distance between the fixed rotational axis and a point of contact of the cutting unit with the skin may be at most <NUM>. The elongate axis and the fixed rotational axis may not cross. The maximum distance between either the driving bridge or the socket, and the fixed rotational axis may be <NUM>.

It may be that the base bearing surface has a curvature of a first radius about the fixed rotational axis. It may be that the counterpart bearing surface has a curvature of a second radius about the fixed rotational axis. It may be that the first radius is the same as the second radius such that the counterpart bearing surface is configured to contact, and cooperate with, the base bearing surface to permit relative rotational sliding movement between the base and the counterpart about the rotational axis.

It may be that the base bearing surface or the counterpart bearing surface comprises a recessed section to reduce a contact surface area between the base and the counterpart. There may be at least two contact points between the counterpart bearing surface and the base bearing surface on either side of the recessed section.

It may be that there are two separate slots and two corresponding pins which are configured to be received in respective slots.

It may be that the counterpart comprises a foundation which is part of a second pivoting mechanism for pivoting the head relative to the base about a second rotational axis which is parallel to the elongate axis.

It may be that the foundation is a first bar of a four-bar linkage, the body comprises a second bar of a four-bar linkage, and the foundation and the body are coupled together with a third bar and a fourth bar of a four-bar linkage.

It may be that the fixed rotational axis is positioned between the driving bridge and the socket.

According to a second aspect, there is provided a hair cutting appliance comprising: a mounting assembly according to the first aspect; a motor configured to be coupled to the driving unit; and a handle configured to be attached to the mounting assembly.

<FIG> shows a hair cutting appliance <NUM> comprising a handle <NUM> for a user to hold the hair cutting appliance <NUM>, and a mounting assembly <NUM>, attached to the handle <NUM>. A motor <NUM> is disposed within the handle <NUM>, and a transfer shaft <NUM> extending from the motor <NUM> is coupled to the mounting assembly <NUM>.

<FIG> shows a first example mounting assembly 20a for attaching to the handle <NUM> of the hair cutting appliance <NUM>.

The mounting assembly 20a comprises a head <NUM> comprising a body <NUM> extending along an elongate axis <NUM> and a driving bridge <NUM>. The head <NUM> is configured to receive a cutting unit, such as a blade. The driving bridge <NUM> is configured to reciprocally move relative to the body <NUM> along the elongate axis <NUM>. The driving bridge <NUM> is also coupled to the cutting unit, so that, when the driving bridge moves reciprocally relative to the body <NUM>, the cutting unit is also moved reciprocally relative to the body <NUM>, to enable it to cut hairs.

The first example mounting assembly 20a comprises a driving unit <NUM> with a driving axle <NUM> and a socket <NUM> fixed together. The socket <NUM> is configured to cooperate with the motor <NUM>, via the shaft <NUM>, to impart rotary motion to the socket <NUM> and the driving axle <NUM>. The driving axle <NUM> comprises an eccentric pin <NUM> which is received in a channel of the driving bridge <NUM>, to cooperate with the driving bridge <NUM>, to impart reciprocating motion to the driving bridge <NUM> by rotation of the driving axle <NUM>. The driving unit <NUM> is therefore configured to transfer rotary motion of the motor into reciprocating motion of the driving bridge <NUM>. The socket <NUM> is configured to receive, and cooperate with, the shaft <NUM> at various different angles, so that the socket <NUM> can pivotably move relative to the motor <NUM> without detrimentally impacting the ability of the driving unit <NUM> to transfer rotary motion of the motor <NUM> into reciprocating motion of the driving bridge <NUM>.

The first example mounting assembly 20a comprises a base <NUM> which is connected to the head <NUM> with a first pivoting mechanism <NUM>. The base <NUM> is configured to couple to the handle <NUM>.

In this example, the first pivoting mechanism <NUM> comprises the base <NUM> and a counterpart <NUM> which is moveably coupled to the head <NUM>. The first pivoting mechanism <NUM> is configured to permit relative movement between the head <NUM> and the base <NUM> about only a fixed rotational axis <NUM> which is perpendicular to the elongate axis <NUM>.

The first pivoting mechanism <NUM> comprises a base bearing surface <NUM> on the base <NUM> and a counterpart bearing surface <NUM> on the counterpart <NUM>. The base bearing surface <NUM> and the counterpart bearing surface <NUM> cooperate to permit relative rotational sliding movement of the base <NUM> and the counterpart <NUM> coupled to the head <NUM> about only a fixed rotational axis <NUM> (shown as going into the page on <FIG>). The fixed rotational axis <NUM> is substantially perpendicular to the elongate axis <NUM>. In this example, the fixed rotational axis <NUM> is positioned between the driving bridge <NUM> and the socket <NUM>, so that a connection between the motor <NUM> and the socket <NUM> (in this case the shaft <NUM>), does not inadvertently decouple from the socket <NUM> when the head <NUM> is rotated about the fixed rotational axis <NUM> relative to the base <NUM>. In this example, the fixed rotational axis <NUM> is at a receiving face of the socket <NUM>. In other examples, the fixed rotational axis may be within <NUM> from the receiving face of the socket <NUM>. The closer the fixed rotational axis to the socket <NUM>, the less likely that the socket <NUM> will decouple from the shaft of the motor <NUM> during pivoting of the counterpart <NUM> from the base <NUM>.

In this example, the base bearing surface <NUM> is a concave surface having a first radius about of curvature the fixed rotational axis <NUM>, and the counterpart bearing surface <NUM> is a convex surface having a second radius of curvature about the fixed rotational axis <NUM>. In this example, the first radius and the second radius are the same such that the convex surface of the counterpart bearing surface <NUM> corresponds to the concave surface of the base bearing surface <NUM>, and the base bearing surface <NUM> is in sliding contact with the counterpart bearing surface <NUM>, such that the surfaces permit relative rotational movement about only the fixed rotational axis <NUM> between the base <NUM> and the counterpart <NUM>.

In this example, the counterpart bearing surface <NUM> comprises a recessed section <NUM> to reduce a contact surface area between the base <NUM> and the counterpart <NUM>, to thereby reduce complexity of the parts and reduces the need for high precision machining to make the surfaces coincide. The recessed section <NUM> of the counterpart bearing surface <NUM> in this example is positioned such that the counterpart bearing surface <NUM> still comprises two surfaces on opposing sides of the recessed section <NUM>, such that there are two contact points or contact lines between the counterpart bearing surface <NUM> and the base bearing surface <NUM> on either side of the recessed section <NUM>. It will be appreciated that there may be more than one recessed section, and that there may be more than two contact points.

In some examples, the recessed section may be in the base bearing surface or in both surfaces. In examples, where both surfaces comprise recessed sections, the length of one of the sides must be double the displacement of the bearing, otherwise the counterpart and base would decouple (for example in <FIG>). In other examples, the bearing surfaces may be continuous such that there is no recessed section.

In this example, the counterpart <NUM> is moveably coupled to the head <NUM> with a second pivoting mechanism <NUM>, which is configured to permit relative rotational movement between the head <NUM> and the base <NUM> about a second rotational axis <NUM>, which is parallel to the elongate axis <NUM>. In this example, the counterpart <NUM> comprises a foundation which is a part of the second pivoting mechanism <NUM>. In this example, the foundation is a first bar of a four-bar linkage, the body <NUM> comprises a second bar of a four-bar linkage, and the foundation and the body <NUM> are coupled together with a third bar and a fourth bar of a four-bar linkage. In this example, the second rotational axis <NUM> is therefore a virtual axis, which moves dependent on the relative position of the four-bar linkage.

In other examples, the foundation and the base of the head may be coupled with a simple pivot which allows pivoting movement about the second rotational axis <NUM>, where the second rotational axis is fixed.

In other examples, the counterpart may be fixedly coupled to the head, so that it is unitary with the head, and so that the head may not be moveable relative to the base about a second rotational axis parallel to the elongate axis. In other examples, although the head may not be moveable relative to the base about a second fixed axis, the base may be moveable relative to the handle about an axis parallel to the elongate axis, such that the head is still moveable relative to the handle about two perpendicular axes.

<FIG> shows a second example mounting assembly 20b. The second example mounting assembly 20b is similar to the first example mounting assembly 20a, but differs in having a different first pivoting mechanism <NUM> which further connects the head <NUM> and the base <NUM>. In this example, the first pivoting mechanism <NUM> is similar to the first pivoting mechanism <NUM> in that it comprises the base <NUM> and the counterpart <NUM>, having a base bearing surface <NUM> and a counterpart bearing surface <NUM>, but differs in that the counterpart bearing surface <NUM> is disposed on opposing sides of a slot <NUM> in the counterpart <NUM>, and the base bearing surface <NUM> comprises two protrusions on the base <NUM> (this could be considered to be both the base bearing surface <NUM> having a recessed section and the counterpart bearing surface <NUM> having a recessed section). It differs further in additionally having a pin <NUM> which is a part of the base <NUM> which is received within the slot <NUM>. In other examples, the pin may be a part of the counterpart while the slot may be a part of the base. The pin <NUM>, in this example, is only loosely received in the slot <NUM> in this example to avoid over-constraining the system. In other words, the slot <NUM> is made wider than the pin <NUM> so that the pin <NUM> is not necessarily in contact with an inner surface of the slot <NUM> unless the counterpart <NUM> and the base <NUM> are pushed towards one another or pulled away from one another, in which case the pin <NUM> acts against an inner surface of the slot <NUM> to prevent decoupling of the base <NUM> from the counterpart <NUM>. The pin <NUM> and the slot <NUM> can also be used to define end points of rotation, to prevent over rotation of the counterpart <NUM> relative to the base <NUM>. The pin may have a circular section, or a curved section corresponding to the curvature of the slot. In other examples, the counterpart bearing surface may comprise the inner surface of the slot, while the base bearing surface may comprise the outer surface of the pin.

<FIG> shows a third example mounting assembly 20c which is similar to the second example mounting assembly 20b, but differs in comprising a different base bearing surface <NUM> and counterpart bearing surface <NUM> which are inverted so that the base <NUM> and the counterpart <NUM> are configured to rotate about a different fixed rotational axis <NUM> which, in this example, is in the centre of the driving bridge <NUM>. In this example, the base bearing surface <NUM> comprises an inner surface of two slots, and the counterpart bearing surface <NUM> comprises an outer surface of two corresponding pins, which are configured to be received in each slot respectively. In other examples, the counterpart bearing surface may comprise the inner surfaces of the two slots, while the base bearing surface may comprise the outer surfaces of the two pins. In yet other examples, there may be only a single slot and pin, or more than two slots and corresponding pins. In essence, the embodiment of <FIG> combines the embodiments of <FIG> and <FIG> together, where the pin and slot act as both the bearing surfaces and the constraint to prevent separation of the counterpart <NUM> and the base <NUM>. In this example, the fixed rotational axis <NUM> may be within <NUM> from the driving bridge <NUM>.

A fixed rotational axis, as referred to herein, is intended to mean a rotational axis which is stable and does not move relative to the head <NUM> or the base <NUM>. In this example, the distance between the fixed rotational axis <NUM>, <NUM> and a point of contact of the cutting unit with the skin (e.g., a top surface of the head <NUM> furthest from the base <NUM>) may be at most <NUM>. In some examples, the second rotational axis <NUM> and the elongate axis <NUM> may not cross the fixed rotational axis <NUM>, <NUM>. In other words, the fixed rotational axis <NUM>, <NUM> may not be in line with a part of the head <NUM> configured to receive the cutting unit.

Claim 1:
A mounting assembly for a hair cutting appliance, the mounting assembly comprising:
a head comprising a body, extending along an elongate axis, and a driving bridge, the head being configured to receive a cutting unit, wherein the driving bridge is configured to couple to the cutting unit and to reciprocally move relative to the body along the elongate axis;
a base connected to the head with a first pivoting mechanism;
a driving unit comprising a driving axle and a socket, the driving axle comprising an eccentric pin cooperating with the driving bridge to impart reciprocating motion to the driving bridge, and the socket being configured to cooperate with a motor;
wherein the first pivoting mechanism comprises:
a base bearing surface on the base,
a counterpart coupled to the head, the counterpart comprising a counterpart bearing surface,
wherein the base bearing surface and the counterpart bearing surface are configured to cooperate to permit relative rotational sliding movement of the base and the head about only a fixed rotational axis which is perpendicular to the elongate axis
wherein one of the base bearing surface or the counterpart bearing surface comprises an inner surface of a slot having a curvature about the fixed rotational axis, and wherein the other of the base bearing surface or the counterpart bearing surface comprises an outer surface of a pin which is configured to be received within the slot.