Patent Publication Number: US-9427879-B2

Title: Device for trimming hair

Description:
FIELD OF THE INVENTION 
     The present invention relates to a device for trimming hair. In particular, the present invention relates to a device for trimming hair including a housing with a head portion which is rotatably mounted to the housing. 
     BACKGROUND OF THE INVENTION 
     Electric hair cutting appliances are generally known, and include trimmers, clippers and shavers whether powered by mains supplied electricity or batteries. Such a device is generally used to trim body hair, in particular facial and head hair to allow a person to have a well groomed appearance. 
     Commonly, conventional devices for cutting hair comprise a main body forming an elongate housing having a front or cutting end and an opposite handle end. A cutting blade assembly is disposed at the cutting end and includes a stationary blade element with a movable blade element which moves in a reciprocal manner against the stationary blade element. The cutting blade assembly extends from the cutting end and is fixed in a single position relative to the body, such that the orientation of the cutting element is determined by a user orientating the main body of the device. 
     A comb attachment is generally mounted to the cutting end of a conventional device to position hair to be cut by the cutting blade assembly. Typically, the comb attachment slides over the cutting blade assembly and spaces the cutting elements away from the surface of the skin from which the hair extends. This allows a uniform length of hair to be cut and allows different sizes of comb elements to be attached, or an adjustable comb element to be attached, to vary the length of hair to be cut. 
     Further, it is also possible to remove the comb attachment from the cutting end so that the blade assembly is exposed. This allows the cutting assembly to be used for precise trimming of hair, particular outer contours of the a hairline or beard. 
     However, one problem with such conventional devices is the fixed relationship between the housing and the cutting blade assembly and comb attachment. As the cutting blade assembly and comb attachment is fixedly mounted to the main body, it is necessary to correctly align the cutting blades by moving the handle into the correct orientation. Therefore, a user must position their hand and arm in potentially awkward or uncomfortable positions. Furthermore, if a user does not precisely orientate the device, then the cutting blade assembly will be orientated incorrectly, which leads to an unsatisfactory hair cut or trim. It is often difficult for a user attempting to trim their own hair to handle a conventional device, because of the low visibility to the back of the head during use and so the possibility of the user injuring themselves, or getting an unequal haircut, is very high. 
     In view of the foregoing, devices for cutting hair have been devised with a pivotable head on which is mounted the blade assembly and comb attachment. The head is allowed to pivot so that the blade assembly and comb attachment are able to align with the contours of the head and provide a more uniform cut. Furthermore, it is easier and more comfortable for a user to trim their own hair when the comb attachment has some rotational freedom during use which enables, the comb attachment and hence the blade assembly to follow the shape of the human head. 
     However, the pivotable head is a disadvantage when it is desired to conduct precise trimming of the hair when the comb element is removed. In such a situation, there is the problem that it is difficult to precisely position the cutting element when the head is inclined to pivot relative to the body, and so can cause irregular and undesired cuts. 
     SUMMARY OF THE INVENTION 
     Therefore, it is an object of the invention to provide a device for clipping hair which substantially alleviates or overcomes the problems mentioned above and allows the precise positioning of a cutting blade arrangement when a comb element is removed from the device. 
     According to the present invention, there is provided a device for trimming hair comprising a housing and a head portion with a cutting blade assembly, wherein the head portion is rotatably mounted to the housing and a comb attachment is releasably attachable to the device to extend over the cutting blade assembly, the device further comprising a locking means configured to fixedly engage the head portion with the housing when a comb attachment is detached from the device, such that the head portion is prevented from rotating relative to the housing, and disengage the head portion from the housing when a comb attachment is attached to the device, such that the head portion is rotatable relative to the housing. 
     Preferably, the locking means further comprises a locking member which is configured to move between an engaged position, in which the head portion is prevented from rotating relative to the housing, when a comb attachment is detached from the device, and a disengaged position, in which the head portion is rotatable relative to the housing, when a comb attachment is attached to the device. 
     The locking member may be urged into its disengaged position by a comb attachment acting on the locking member. 
     In a preferred embodiment, the device further comprises resilient means to urge the locking member from its engaged position into its disengaged position. 
     The locking member may be mounted in the housing. 
     Conveniently, the locking means further comprises a locking protrusion which rotates with the head portion such that, when the locking member is in its engaged position, the locking member abuts against the locking protrusion to prevent the head portion from pivoting relative to the housing. 
     The device may further comprise a motor assembly disposed in the housing to drive the cutting blade assembly, wherein the motor assembly rotates with the head portion and the locking protrusion extends from the motor assembly. 
     Advantageously, the locking protrusion extends in a radial direction from the axis of rotation of the motor assembly, and the locking member moves along an axis parallel to the axis of rotation. 
     In one embodiment, the locking member is mounted on the head portion. 
     Preferably, the locking member further comprises a slot and the locking means further comprises a locking pin which is locatable in the slot to fixedly mount the head portion relative to the housing and prevent rotation relative thereto. 
     The locking pin may be disposed on the housing. 
     The locking member may further comprise an arcuate face, along which the locking pin slides when the locking member is urged into its engaged position. 
     Conveniently, an arm of the locking member extends through an aperture in the head portion against which a comb attachment abuts to urge the locking member. 
     Advantageously, the device further comprises a comb attachment releasably mounted to the head portion. 
     Preferably, the comb attachment comprises an urging protrusion which acts on the locking member to urge the locking member into its disengaged position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  illustrates a perspective view of a device for clipping hair according an embodiment of the present invention; 
         FIG. 2  illustrates a perspective view of the device shown in  FIG. 1 , showing a head portion in a neutral position with a comb attachment attached thereto; 
         FIG. 3  illustrates a perspective view of the device shown in  FIG. 2 , with the head portion and comb attachment rotated in an anti-clockwise direction relative to the main body; 
         FIG. 4  illustrates a cut-through perspective view of the device shown in  FIG. 1 , with the head portion and comb attachment in a neutral position relative to the main body; 
         FIG. 5  illustrates a cut-through perspective view of the device shown in  FIG. 4 , with the head portion and comb attachment rotated relative to the main body; 
         FIG. 6  illustrates a sectional view of the device shown in  FIG. 1 ; 
         FIG. 7  illustrates a perspective view of the head portion of the device shown in  FIG. 1 , according to one embodiment of the invention; 
         FIG. 8  illustrates a plan view from below of the head portion of the device shown in  FIG. 7  with a sub-frame of the housing and a locking pin, and a locking member shown in an engaged position with the locking pin; 
         FIG. 9  illustrates a perspective view of the head portion of the device shown in  FIG. 8 ; 
         FIG. 10  illustrates a plan view from below of the head portion of the device shown in  FIG. 7  with a sub-frame of the housing, a locking pin, and a comb attachment attached, and the locking means shown in a disengaged position away from the locking pin; 
         FIG. 11  illustrates a perspective view from below of the head portion of the device shown in  FIG. 10 ; 
         FIG. 12  illustrates a plan view from below of the head portion of the device shown in  FIG. 7  with a sub-frame of the housing, a locking pin, and a comb attachment attached, and the locking means shown in a disengaged position away from the locking pin, wherein the head portion is rotated with respect to the sub-frame of the housing; 
         FIG. 13  illustrates a perspective view from below of the head portion of the device shown in  FIG. 12 ; 
         FIG. 14  illustrates a perspective view of part of the device shown in  FIG. 1  according to another embodiment of the invention; 
         FIG. 15  illustrates a magnified perspective view of the part of the device shown in  FIG. 14  with a locking means in an engaged position; 
         FIG. 16  illustrates a perspective view of the part of the device shown in  FIG. 14  with a locking means in an engaged position, but a with a comb attachment omitted; 
         FIG. 17  illustrates a magnified perspective view of the part of the device shown in  FIG. 16  with a locking means in an engaged position, but a with a comb attachment omitted; 
         FIG. 18  illustrates a perspective view of the part of the device shown in  FIG. 14  with a comb attachment shown attached; 
         FIG. 19  illustrates a magnified perspective view of the part of the device shown in  FIG. 18  with a comb attachment shown attached; 
         FIG. 20  illustrates another perspective view of the part of the device shown in  FIG. 14  with the locking means in an engaged position; and 
         FIG. 21  illustrates another perspective view of the part of the device shown in  FIG. 20  with a comb attachment attached and the locking means in a disengaged engaged position. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Referring now to the drawings, there is shown in  FIGS. 1 to 13  a first embodiment of a device for trimming hair  1  comprising a body  2  including an elongate housing  3  with a cutting or front end  4 , and a handle or rear end  5 . An opening  6  is formed in the front end  4  of the body  2  and a head portion  7  extends from the body  2  and is mounted thereto. 
     The outer surface  7  of the elongate housing  3  is tapered outwardly from the rear end  6  to the front end  4  to provide a more ergonomic holding position and to improve the aesthetic appearance of the device  1 , although it will be appreciated that other housing arrangements are envisaged. An operating button  8  is provided on the housing to operate the device  1 , as will be explained hereinafter. 
     A cutting blade assembly  10  is mounted on the head portion  9 , and comprises a first fixedly mounted blade (not shown) and a second movable blade (not shown) abutting against the first fixedly mounted blade. Each blade (not shown) has an array of teeth at a cutting edge  11  of the blade assembly  10  which overlap with each other so that, when the second movable blade moves in a reciprocal linear manner relative to the first blade, edges of the teeth form a cutting surface that engages and severs the hair. Such a cutting blade assembly  10  is conventional and so no further discussion of the arrangement will be given herein. Although the present embodiments are described with respect to the above cutting blade arrangement, it will be appreciated that the cutting blade assembly is not limited thereto and that alternative cutting blade arrangements are envisaged, such as a rotational blade arrangement. 
     Referring to  FIGS. 4, 5 and 7 to 13 , the head portion  9  further comprises a chassis  12  to which the cutting blade assembly  10  is mounted, and an end cover  13  which extends into the housing  3 . The chassis  12  and the end cover  13  are fixedly mounted to each other, or formed together. Referring now to  FIGS. 4 and 5 , the end cover  13  extends into the housing  3  and covers the opening  6  to the housing  3 , and the head portion  9 , including the chassis  12  and end cover  13 , is pivotally mounted to the front end  4  of the body  2 . Therefore, the head portion  9  is pivotable about a longitudinal axis extending through a plane of the head portion  9  and extending longitudinally through the elongate housing  3 . Alternatively, the head portion  9  pivots on a plane extending at an oblique angle to the longitudinal axis extending along the elongate housing  3 . The cutting edge  11  of the blade assembly  10  extends from the chassis  12  to allow hair to be trimmed, as will be explained in detail hereinafter. 
     The end cover  13  is supported on an arcuate shoulder  14  extending around the inner surface of the housing  3  proximate to the opening  6 . An upper lip (not shown) extends over the periphery of end cover  13  to rotatably mount the end cover  13  and therefore the head portion  9  to the housing  3 , such that the head portion  9  extends from the housing  3 . The housing  3 , chassis  12  and end cover  13  are formed from a moulded plastic; however it will be appreciated that any suitable material may be used. 
     A sub frame  15  is fixedly mounted in the housing  3  proximate the front end  4  of the body  2  and extends substantially across the opening  6  to the housing  3 . A motor assembly is disposed in the housing  3  to drive the cutting blade assembly  10  and comprises an electric motor  16  mounted in a motor housing  18 . The electric motor  16  is electrically connected to a battery (not shown) disposed in an electrical component space  17  formed proximate to the rear end  5  of the housing  3 . Although in the present embodiments electrical power is provided by a battery, it will be appreciated that it is envisaged that electrical power may be supplied by alternative means, for example a mains power lead connecting with a connector (not shown) formed at the rear end  5  of the housing  3 . 
     The motor assembly  18  is rotatably mounted in the housing  3  at one end of the assembly such that the motor housing  18  and the motor  16  mounted in the motor housing  18  is rotatable in the housing  3  about an axis extending substantially longitudinally in the housing  3 . An actuating rod  19  extends from the electric motor  16  and extends through the sub frame  15  to a cutting blade actuating mechanism  20  which extends through an aperture  20  (refer  FIGS. 8 and 9 ) formed in the end cover  13  and the chassis  12  to transmit the operative power of the electric motor  16  to the cutting blade assembly  10  to drive the cutting blade assembly  10 . 
     Therefore, the motor assembly is fixedly connected to the head portion  9 , such that when the head portion is urged to rotate relative to the housing  3 , the motor assembly is urged to rotate therewith. 
     A return spring (not shown) is mounted to the motor housing  18  to urge the motor housing  18  and therefore the electric motor  16  and the head portion  9  into a neutral position, whereby the head portion  9  is not rotated relative to the housing  3 . 
     A comb attachment  20  is releasably attached to the head portion  9  and is rotatable with the head portion  9 . The comb attachment  20  guides the hair to the cutting blade assembly  10  and allows a uniform length of hair to be cut by spacing the cutting edge  11  of the cutting blade assembly  10  from the surface of a user&#39;s head. The comb attachment  14  comprises a plurality of parallel rails  22  evenly spaced from each other such that hair is guided between the rails  22  to the cutting edge  11  of the blade assembly  10 . The rails  22  extend from a support section  23  which mounts to the head portion  9 . In the present embodiment, the distance from the outer edge of the rails  22  to the cutting edge  11  of the cutting blade assembly  10  is variable to allow different lengths of hair to be cut. However, it will be appreciated that different comb attachments may be used to vary the distance between the cutting edge  11  of the blade assembly  10  and the outer edge of the rails  22 . The comb attachment is formed from a moulded plastic; however it will be appreciated that any suitable material may be used. 
     The support section  23  of the comb attachment  20  comprises a pair of outer arm portions  24  from which the rails  22  extend, and an elongate arcuate mounting section  25  which extends from the outer arm portions  24 . When the comb attachment  20  is mounted to the head portion  9 , the arcuate mounting section  25  extends into the housing  3 . Although the comb attachment  20  is described herein as being fixedly attached to the head portion  9 , it will be appreciated that in an alternative embodiment the comb attachment  20  may be slidably attached to the body  2 , such that the comb attachment  20  is retained by the body  2 , but is capable of rotating relative to the body  2 . 
     A retaining mechanism (not shown) retains the comb attachment  20  in place and prevents it from falling off, but allows the comb attachment  20  to be easily removed when a suitable amount of force is applied. 
     Referring now to  FIGS. 7 to 13 , a locking means  30  according to a first embodiment of the present invention is shown. The locking means  30  prevents rotation of the head portion  9  relative to the housing  3  when the head portion  9  is urged to rotate. The head portion locking means  30  is engaged to prevent rotation of the head portion  9  when the comb attachment  20  is attached to the head portion  9 , and is disengaged to allow rotation of the head portion  9  due to the head portion  9  being urged to rotate when the comb attachment  20  is removed from the head portion  9 . 
     The head portion locking means  30  comprises a locking member  32  and a resilient element  33 . The locking member  32  has a central engaging portion  34  with upper and lower planar faces and an arcuate edge  37 . An engaging slot  38  is formed in the central engaging portion  34  extending into the central engaging portion  34  from a mid-point of the arcuate edge  37 . Parallel urging arms  36  extend from opposing side edges of the locking member, spaced by the central engaging portion  34 . A flat edge  39  extends along the opposite side to the arcuate edge  37  against which the resilient element  33  locates. 
     The end cover  13  comprises an end face  40  and an outer wall  42  upstanding from the peripheral edges of the end face  40  and extending there around to form a recessed region. Opposing parallel tracks  43  are formed in the recessed region extending to the outer wall  42  of the end cover  13  in which opposing side edges of the locking member  32  and the parallel urging arms  36  locate so that the locking member  32  is slidable along the tracks  43 . An aperture  41  is formed through the outer wall  42  at the end of each track  43  such that the parallel urging arms  36  are slidable through each aperture to extend from the outer face of the outer wall  42 . 
     A resilient element locating pin  44  upstands in the recessed region of the end cover  13  and the resilient element  33  locates between the locating pin  44  and the locking member  32 . The resilient element  33  in this embodiment is a compression spring which urges the urging arms  36  through the apertures in the outer wall  42  to extend from the end cover  13 . 
     A locking pin  45  (refer to  FIGS. 8 and 9 ) upstands from the sub-frame  15  and extends into the recessed region of the end cover  13 . The locking member  32  is urged against the locking pin  45 , and so the locking pin  45  locates against the arcuate edge  37  or in the slot  38 , dependent on the rotatable orientation of the head portion  9  with respect to the body  2 , as will be explained hereinafter. 
     Operation of the above embodiment will now be described with reference to  FIGS. 1 to 13 , and in particular  FIGS. 8 to 13 . 
     A user holds the device for clipping hair  1  by the elongate housing  3 , and the comb attachment is initially detached from the head portion  9 . In this situation the resilient element  33  urges against the flat edge  39  of the locking member  32  to urge the locking member  32  towards the outer wall  42  of the end cover  13  such that the urging arms  36  are urged through the apertures in the outer wall  42  to extend from the end cover  13 . The head portion  9  is initially in a neutral position, in which the head portion  9  is not rotated relative to the body  2 . In the neutral position, with the comb attachment detached from the head portion  9  (refer to  FIGS. 8 and 9 ), the resilient element  33  urges the locking member  32  towards the locking pin  45  and so the locking pin  45  locates in the slot  38  formed in the locking member  32 . As the locking pin  45  upstanding from the sub-frame  15  fixedly mounted in the housing  3  is located in the slot  38  of the locking member  32  mounted to the end cover  13  of the head portion  9 , the head portion  9  is fixedly mounted to the housing  3  and so is prevented from rotating relative to the housing  3 . 
     The comb attachment  20  is then slid over the head portion  9 , with the elongate arcuate mounting section  25  sliding into the housing  3  and the rails extending over the cutting blade assembly  10 . The mounting section  25  removably mounts to the end cover  13  and the retaining mechanism (not shown) fixedly holds the comb attachment  20  in place. Although in the present embodiment the comb attachment fixedly mounts to the end cover  13 , it will be appreciated that the comb attachment  20  may be fixedly connected to a component, such as the motor housing  18  which rotates together with the head portion  9 . The comb attachment  20  may also mount to an adjustment mechanism (not shown), which is configured to move the rails  22  towards and away from the cutting blade assembly  10 . This enables the spacing between the cutting edge  11  of the cutting blade assembly  10  and the rails  22  to be varied and so change the length of hair to be cut by a user. 
     As the comb attachment  20  is slid over the head portion  9 , contact surfaces (not shown) of the mounting section  25  contact angled end surfaces (not shown) of the urging arms  36 . The end surfaces of the urging arms  36  are therefore urged towards the outer wall  42  of the end cover  13  such that the locking member  32  is urged against the resilience of the resilient element  33  and urged away from the locking pin  45 . Therefore, the locking pin  45  slides out of the slot of the locking member  32 , and so slides from an engaged position, in which the head portion is prevented from rotating relative to the body  2 , to a disengaged position, whereby the locking member  32  is retained away from the locking pin  45  and the head portion  9  is rotatable relative to the body  2  (refer to  FIGS. 10 and 11 ). 
     It will be understood that the locking member  32  is retained in its disengaged position whilst the comb attachment  20  is attached to the head portion  9 . The user then operates the device  1  by use of the operating button  8 . Electrical power is supplied to the electric motor  16  by power supply means, such as a battery, disposed in the electrical component space  17 . The motor  16  then drives the cutting blade assembly  10  in a conventional manner, and the device  1  is then operable to trim hair. 
     As a user applies the device to a human head with hair to be cut, the head portion  9  is free to pivot relative to the body  2  because the head portion  9  has some rotational freedom. Therefore, it is easier and more comfortable to use, because the head portion  9  and comb attachment  20  are rotatable to follow the shape of a human head. As the head portion  9  rotates, together with the comb attachment  20 , the motor  16  and motor housing  18  rotate therewith because they are rotatably mounted in the housing  3  and are physically connected thereto by means of the actuating rod  19 . Therefore the cutting efficiency of the device is retained. 
     When a user removes the device from the human head, the head portion  9  and comb attachment  20  rotate back into the neutral position due to one or more return springs (not shown) mounted in the housing and fixedly attached to the motor housing  18 , which in turn is physically mounted to the head portion  18 . However, it will be appreciated that in another embodiment the return springs may be mounted directly to the head portion  9 . 
     If a user desires to use the device to precisely style the outer contours of the hair or the like, then the user detaches the comb attachment  20  from the head portion  9 . When the user exerts a detaching force on the comb attachment  20  by pulling it away from body  2 , then the comb attachment is released from the retaining mechanism (not shown) and the comb attachment slides from the head portion  9 . The urging arms  36  are then released and so the resilient element  33  urges the locking member  32  towards the locking pin  45 . The locking pin  45  then locates in the slot  38  of the locking member  33  to engage the locking member  33 , and so the head portion  9  is fixedly mounted relative to the body  2  and is prevented from rotating. This aids the precise trimming of hair when the comb attachment  20  is not attached to the head portion  9 . 
     If a user removes the comb attachment whilst the head portion  9  is in a rotated position (refer to  FIGS. 12 and 13 ), then the urging arms  36  are released and the locking member  32  is urged towards the locking pin  45  by the resilient element  33 . The locking pin  45  then abuts against the arcuate surface  37  of the locking member  32 . The return springs (not shown) urge the head portion  9  into the neutral position and the locking pin  45  slides along the arcuate surface  37  of the locking member  32 . As the head portion  9  locates in its neutral position, whereby the head portion  9  is not rotated relative to the body  2 , the locking pin  45  slides into the slot of the locking member  32  to engage therewith due to the resilience of the resilient element  33  urging the locking member  33  towards the locking pin  45 . The head portion  9  is then prevented from pivoting relative to the body  2 . 
     Another embodiment of a device for clipping hair will now be described with reference to  FIGS. 1 to 6 and 14 to 21 . The arrangement of this embodiment of a device for clipping hair is generally the same as for the exemplary embodiment described in detail above, and so a detailed description will be omitted herein, and components corresponding to components of the preceding embodiment retain the same reference numerals. 
     However in this embodiment, a head portion locking means  50  is disposed in the housing  3  of the device  1 . The head portion locking means  50  comprises two locking members  52  slidably mounted in the housing  3  diametrically opposite each other and two corresponding resilient elements  53 . Each locking member  52  comprises an upright section  53  and a transverse locking section  54  extending from the upright section  53  (refer to  FIGS. 14 to 17 ). The transverse locking section  54  has an arced contact surface  55  which locates against a respective locking protrusion  56 , as will become apparent hereinafter. 
     Each locking member  52  is slidably mounted to the housing  3  and each locking member  52  has a resilient element (not shown) acting on it to urge the locking members  52  in a longitudinal direction of the elongate housing  3  towards the head portion  9 . In the present embodiment, the resilient elements (not shown) are compression springs, although other resilient means may be used, for example tension springs. Each locking member  52  further includes an end face  51  against which the comb attachment  20  acts, as will be explained below. 
     A pair of locking protrusions  56  radially extend from the motor housing  18 , with a locking protrusion  56  extending from either side of the housing  18 . Each locking protrusion  56  has a locating surface  57  which abuts against the contact surface  55  of the respective locking member  52 . 
     The comb attachment  20  is generally the same as the comb attachment described above for the first exemplary embodiment, however in this embodiment the comb attachment has two inwardly facing tabs (not shown) extending radially inwardly from the mounting section  25  of the comb attachment  20 . Each inwardly facing tab (not shown) abuts against a respective end face  51  of the locking members  52  to urge the locking members  52  in a direction away from the head portion  9  when the comb attachment  20  is attached to the head portion  9 . Each tab (not shown) extends in a circumferential direction to form an inner ridge. 
     Operation of the above embodiment will now be described with reference to  FIGS. 1 to 6 and 14 to 21 . 
     To trim or cut hair using the device for clipping hair  1 , a user holds the device by the elongate housing  3 , and the comb attachment is initially detached from the head portion  9 . Each locking member  52  is urged by its respective resilient element (not shown) towards the respective locking protrusion  56 , and its movement is limited by an end stop (not shown). The head portion  9  is initially in a neutral position, such that the head portion  9  is not rotated relative to the body  2 . In the neutral position, with the comb attachment detached from the head portion  9 , each resilient element (not shown) urges each locking member  52  towards its respective locking protrusion  56 , and so the contact surface  55  of each locking member  52  locates against the locating surface  57  of each locking protrusion  56  extending from the motor housing  18 . As the motor housing  18  is connected to head portion  9  by the actuating member  19  extending from the motor  16  to the cutting blade assembly  10 , then the head portion  9  is fixedly mounted to the housing  3  and so is prevented from rotating relative to the housing  3 . 
     To trim hair to a desired length, a user then slides the comb attachment  20  over the head portion  9 , with the elongate arcuate mounting section  25  sliding into the housing  3  and the rails extending over the cutting blade assembly  10 . The mounting section  25  removably mounts to the end cover  13  and the retaining mechanism (not shown) fixedly holds the comb attachment  20  in place. Although in the present embodiment the comb attachment fixedly mounts to the end cover  13 , it will be appreciated that the comb attachment  20  may be fixedly connected to a component, such as the motor housing  18  which rotates together with the head portion  9 . The comb attachment  20  may also mount to an adjustment mechanism (not shown), which is configured to move the rails  22  towards and away from the cutting blade assembly  10 . This enables the spacing between the cutting edge  11  of the cutting blade assembly  10  and the rails  22  to be varied and so change the length of hair to be cut by a user. 
     As the comb attachment  20  is slid over the head portion  9 , the inwardly facing tabs (not shown) extending from the mounting section  25  abut the end face  51  of each locking member  52 . As the comb attachment  20  is slid further, the tabs urge act against said end faces  51  and urge each locking member  52  against the resilience of the resilient elements (not shown) and away from the head portion  9  of the device. Therefore, the locking members  52  slide relative to the locking protrusions  56  from an engaged position, in which the head portion is prevented from rotating relative to the body  2 , to a disengaged position whereby the contact surface  55  of each locking member  52  is separated from the locating surface  57  of the respective locking protrusion  56 . Once the locking members  52  and locking protrusions  56  are spaced from each other, the motor housing  18  and therefore the head portion are free to rotate, and so in the disengaged position, the head portion  9  is rotatable relative to the body  2 . 
     It will be understood that once the comb attachment  20  is fixedly attached to the head portion  9 , then the locking members  52  are retained in their disengaged position. The user then operates the device  1  by use of the operating button  8 . Electrical power is supplied to the electric motor  16  by power supply means, such as a battery, disposed in the electrical component space  17 . The motor  16  then drives the cutting blade assembly  10  in a conventional manner, and the device  1  is then operable to trim hair. 
     As a user applies the device to a human head, the head portion  9  is free to pivot relative to the body  2  because the head portion  9  has some rotational freedom. Therefore, it is easier and more comfortable to use, because the head portion  9  and comb attachment  20  are rotatable to follow the shape of a human head. As the head portion  9  rotates, together with the comb attachment  20 , the motor assembly also rotates because it is rotatably mounted in the housing  3  and is physically connected thereto by means of the actuating rod  19 . Therefore the cutting efficiency of the device is retained. 
     As the head portion  9  rotates the comb attachment  20  also rotates. Therefore, the tabs of the comb attachment slide relative to the end surface  51  of the locking member  52 . However, the tabs are prevented from sliding off the end surface  51  because they extend in a circumferential direction. 
     When a user removes the device from the human head, the head portion  9  and comb attachment  20  rotate back into the neutral position due to one or more return springs (not shown) mounted in the housing and fixedly attached to the motor housing  18 , which in turn is physically mounted to the head portion  9 . However, it will be appreciated that in another embodiment the return springs may be mounted directly to the head portion  9 . 
     If a user desires to use the device to precisely style the outer contours of the hair or the like, then the user then detaches the comb attachment  20  from the head portion  9 . When the user exerts a detaching force on the comb attachment  20  by pulling it away from body  2 , the comb attachment is released from the retaining mechanism (not shown) and the comb attachment slides from the head portion  9 . The tabs (not shown) are then slid away from the end surface of the locking member  52  and the resilient elements (not shown) urge each respective locking member  52  towards the locking protrusions  56 , from their disengaged position to their engaged position. 
     The contact surface  55  of each locking member  52  then locates against the corresponding locating surface  57  of the respective locking protrusion to abut there against, and so the motor housing  18  and therefore the head portion  9  are prevented rotating relative to the housing. This aids the precise trimming of hair when the comb attachment  20  is not attached to the head portion  9 . 
     If a user removes the comb attachment whilst the head portion  9  is in a rotated position, then the tabs (not shown) are then slid away from the end surface of the locking member  52  and the resilient elements (not shown) urge each respective locking member  52  towards the locking protrusions  56 . The end surface  51  of each locking member  52  then abuts against an end face  59  of each locking protrusion. The return springs (not shown) urge the head portion  9  into the neutral position and the end face  59  of each locking protrusion slides relative to the end surface  51  of each locking member  52 . As the head portion  9  locates in its neutral position, whereby the head portion  9  is not rotated relative to the body  2 , then each locking protrusion  56  disengages from the end surface  51  of its respective locking member  52 , and the locking member is urge to slide into its engaged position. The head portion  9  is then prevented from pivoting relative to the body  2 . 
     Although the locking means  50  as described above comprises locking members  52  which locate against locking protrusions which extend from the motor housing  18 , it will be appreciated that in an alternative embodiment the locking protrusions extend from the head portion  9 , for example the end cover  13  such that the locking members  52  directly engage with the head portion  9 . In particular, the locking members  52  may abut against engaging arms  60  (refer to  FIG. 14 ), extending from the end cover  13 , when the head portion locking means is in its engaged position, whereby the comb attached  20  is detached from the head portion  9 , to prevent rotation of the head portion  9  relative to the body  2 . 
     Although in this embodiment the head portion locking means  50  comprises two locking members  52  spaced diametrically opposite each other in the housing  3  which abut against two locking protrusions extending from the motor housing  18 , it will be appreciated that in an alternative embodiment the locking means  50  has a single locking member  52  which locates against a single locking protrusion, or a pair of locking protrusions to prevent rotation of the motor housing  18  and hence the head portion  9  relative to the housing  2 . 
     Although in the above embodiments the device is used for trimming, cutting or clipping hair on a human head, it will be appreciated that the device is suitable for use in trimming, cutting or clipping hair on animals and other parts of a human body. 
     Although claims have been formulated in this application to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel features or any novel combinations of features disclosed herein either explicitly or implicitly or any generalization thereof, whether or not it relates to the same invention as presently claims in any claim and whether or not it mitigates any or all of the same technical problems as does the parent invention. The applicants hereby give notice that new claims may be formulated to such features and/or combinations of features during the prosecution of the present application or of any further application derived there from.