Abstract:
A hair trimming device is detachably mounted on a handle housing a battery for supplying electric current to a motor located in a drive unit of the trimming device. A trimmer unit includes a plurality of trimmer blade assemblies with different configurations and is rotatable on the drive unit for moving a selected one of the blade assemblies to the operative position in which it is coupled to be driven by the drive unit whilst the other blade assembly which is not in the operative position is uncoupled from the drive output of the drive unit.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to hand-held personal care appliances, and is concerned in particular with a hair trimming device. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is well known for electric dry razors to be equipped with long hair trimming devices for trimming and shaping hair in areas where longer hair is allowed to grow, such as sideburns or moustaches, as well as shaving foils or other forms of cutter for use in areas where it is desired to shave very closely to the skin surface. Usually the trimming device is selectively actuable and it may be movably mounted to the dry razor for adjustment between operative and inoperative positions. In one well known example, a razor with a handle on which a safety razor cartridge is mounted for use as a conventional wet razor, and the handle also includes an electrically driven hair trimmer which can be either fixed in position or movable between a stowed position and a position suitable for use. A common drawback of these known razors is that due to their dual purpose and the trimming devices being of secondary importance in comparison with the main use of the razors for shaving, the trimming devices are not as a rule optionally positioned in relation to the razor handle to facilitate most effective and convenient use. In addition, a single trimmer configuration, which is most commonly relatively long and straight, is not ideal for all hair trimming and shaping needs and demands. 
         [0003]    A battery operated electric razor currently marketed by Braun GmbH, and sold under the trade mark cruZer, is provided with a trimming unit that is mounted on the main casing of the razor for movement from an inoperative position to an operative position. The trimmer unit is provided with two blade assemblies positioned opposite one another with respect to an axis about which the trimmer unit is rotatable for selecting the blade assembly that is to be used. One blade assembly is long and straight and the other is relatively short and curved. When the trimmer unit is switched on both blade assemblies are driven although only one can occupy the operative position in which it is usable for trimming and shaping hair. Thus, the battery power consumed in driving the inoperatively positioned blade assembly is wasted. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention addresses the drawbacks of the known trimming devices as explained above and provided in accordance with the invention is a hair trimming device comprising: a drive unit providing a drive output; a trimmer unit including a plurality of blade assemblies, the trimmer unit being movably mounted to the drive unit for bringing a selected one of the blade assemblies into an operative position; a coupling arrangement for coupling the blade assemblies to the drive output whereby the selected blade assembly in the operative position is coupled to be driven by the drive output and the or each other blade assembly is uncoupled from the drive output. 
         [0005]    With a hair trimming device embodying the invention only that blade assembly in an operative hair trimming position is driven so that battery power will be consumed more efficiently. Nonetheless different blade assembly configurations are available for easy selection according to the needs and preferences of the user. In a preferred construction the trimmer unit is rotatable relative to the drive unit, which is especially convenient for changing the selected blade assembly in the operative position. In addition the trimmer unit can be translatable relative to the drive unit to displace a blade assembly away from the operative position and to uncouple the blade assembly from the drive output of the drive unit. In a particular construction the trimming unit is rotatably connected to a mounting plate, and the mounting plate is connected to the drive unit for translatory movement. 
         [0006]    The drive unit can be mounted firmly on a handle of a hand held hair trimming appliance. In a preferred embodiment the trimming device is detachably connected to a handle which includes a battery compartment for accommodating a battery to supply electric current for driving a motor housed to the drive unit. The detachable handle can then be disconnected from the hair trimming device to facilitate recharging a rechargeable battery housed in the handle and/or for use with other forms of operating head, such as to form a vibrating safety razor by assembly with a separate safety razor operating head. 
         [0007]    The drive output of the drive unit may comprise a reciprocally driven output member, and the drive unit conveniently includes a rotary motor and a transmission mechanism to convert rotation of a motor shaft into reciprocation of the drive output member. The transmission mechanism may comprise an eccentric connected to the motor shaft and engaged with a bridge member that is carried by a pair of parallel pivotal links whereby the bridge member is reciprocated in response to rotation of the motor shaft. 
         [0008]    In an especially convenient embodiment each blade assembly includes a blade driving element, and the coupling arrangement comprises a slot defined in each blade driving element for cooperation with the drive output member. Furthermore, each slot includes a driving section and a mouth section which converges towards the driving section for guiding the drive output member into the driving section when the blade assembly is moved to the operative position. A simple construction is achieved with at least one and preferably each blade assembly comprising a first trimmer blade fixed with respect to the trimmer unit and a second blade guided for reciprocation relative to the first trimmer blade and connected to the blade driving element. 
         [0009]    The foregoing and other features and advantages of the invention will be more fully understood from the following detailed description of a preferred embodiment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a front perspective view showing a trimming device in accordance with the invention adjusted with a first trimming blade assembly in an operative position; 
           [0011]      FIG. 2  is a front perspective view showing the trimming device of  FIG. 1  adjusted with a second trimming blade assembly adjusted to the operative position; 
           [0012]      FIG. 3  is a cross-section through the trimming device of  FIGS. 1 and 2  along with a handle to which the trimming device is detachably connectable; 
           [0013]      FIG. 4  is a front perspective view showing the drive unit of the trimming device of  FIGS. 1 to 3 ; 
           [0014]      FIG. 5  is a front elevational view showing the interior of the drive unit; 
           [0015]      FIG. 6  is a rear elevation of the trimmer unit of the trimming device as shown in  FIG. 1  with the first blade assembly in the operative position; 
           [0016]      FIG. 7  is a rear elevation of the trimmer unit of the trimming device as shown in  FIG. 2  with the second blade assembly in the operative position; and 
           [0017]      FIG. 8  is a perspective illustration showing the motor and transmission of the drive unit in assembly with the trimmer unit. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    Illustrated in the drawings is a hand held personal grooming appliance comprising a hair trimming device  1  and a handle  2  to which the trimming device is adapted to be detachably connected ( FIG. 3 ). The handle  2  includes a battery compartment in which a rechargeable battery  3  is accommodated, a switch arrangement  4  for controlling supply of electric current from the battery  3  to the trimming device when mounted to the handle. A coupling is provided for electrically and mechanically connecting the handle to the trimming device, the coupling comprising a female coupling member  5  on the handle  2  and a male coupling member  6  on the trimming device  1 . The female coupling member  5  includes a sleeve portion  7  located at the upper end of the handle and provided with a pair of symmetrical bayonet slots  8  with locking recesses  9  at their ends. Positioned centrally within the sleeve portion  7  is a first electrical contact  10  which is spring-loaded and urged axially towards the upper end of the handle. The male coupling member  6  has a plug  11  adapted to mate with the female coupling member by sliding engagement in the sleeve portion  7 , and the plug part has a pair of diametrically opposed pin projections  12  arranged for cooperation with the respective bayonet slots  8 . A second electrical contact  13  is located centrally within the plug part  11  with an electrical insulator  14  being disposed therebetween. When the male and female coupling members  5 ,  6  are fully engaged the first and second contacts  10 ,  13  are pressed into close abutment due to the spring loading of the first contact, and this spring loading also serves to urge the pin projections  12  into the locking recesses  9  of the bayonet slots  8  to secure the trimming device  1  against unintentional disconnection from the handle  2 . The sleeve portion  7  and the plug part  11  form further electric contacts that cooperate to complete a circuit for the flow of electrical current between the battery in the handle and the trimming device. The trimming device  1  includes a hood or shroud  15  which surrounds the plug part  11  for enclosing the male and female members of the bayonet coupling to preclude ingress of moisture to the electrical contacts. The female member carries an annular seal  16 , such as an O-ring seal, disposed in a peripheral groove provided on the sleeve portion  7  axially inwardly of the bayonet slots  8 , and the shroud  15  has a close fit over the seal  16  to ensure a watertight connection between the shroud and the handle when the male and female coupling members are engaged. 
         [0019]    The trimming device includes a drive unit  20  and a trimmer unit  21 . The male coupling member  6  and the shroud  15  are provided on a housing  22  of the drive unit in which is housed an electric rotary motor  23  and a transmission mechanism  24  for converting rotary motion of a motor shaft  25  into reciprocation of a drive output member  26  in the form of a drive pin. The electric terminals of the motor are connected to the electrical contacts  11  and  13  of the trimming device for supply of current from the battery  3  in the handle for driving the motor. The transmission mechanism includes a bridge member  27  carried on a pair of pivotal links  28  pivoted to the housing  22  so that the bridge member is capable of reciprocating in the housing of the drive unit, an eccentric  29  connected to the motor shaft  25  being engaged with the bridge member to cause it to reciprocate when the motor shaft is driven by the motor. The drive output pin  26  is firmly fixed to the bridge member  27  and protrudes forwardly from the drive unit  20  into the trimmer unit  21 . Connected to the front of the drive unit is a mounting plate  30  for the trimmer unit  21 , the mounting plate being guided for up and down translatory movement relative to the drive unit for purposes which will become clear. The trimmer unit is held to the mounting plate  30  by a flanged circular collar  31  which is engaged in corresponding shaped hole in the mounting plate so that the trimmer unit  21  is able to rotate relative to the mounting plate  30  and hence also the drive unit  20 . The trimmer unit includes a first trimmer blade assembly  32  and a second trimmer blade assembly  33 . The first blade assembly  32  is comparatively long and straight and includes a first trimmer blade  34  fixedly mounted to a face plate  35  of the trimmer unit, and a second trimmer blade  36  guided for reciprocation relative to the first trimmer blade and attached to a blade driving element  37 . The second blade assembly  33  is relatively short with a convex profile and includes a first trimmer blade  38  fixedly mounted to the face plate  35  and a second trimmer blade  39  guided for reciprocation along a curved path relative to the first trimmer blade  38  and attached to a blade driving element  40  which is mounted to the face plate  35  by a pivot  41 . Each of the blade driving elements  37 ,  40  includes a slot  42  with a narrow driving section in which the drive output pin  26  is engageable for reciprocating the blade driving element and also reciprocating the trimmer blade attached to the blade driving element, and a mouth section which converges towards the driving section for guiding the drive output pin  26  into the driving section. As best seen in  FIGS. 6 and 7 , the slots  42  are aligned but face in opposite directions with the mouth sections overlapping. 
         [0020]    When the mounting plate  30  is displaced upwardly relative to the drive unit the drive output pin  26  projects into the trimmer unit  21  along the axis of the collar  31  and passes through the mouth sections of the slots  42  in the blade driving elements  37 ,  40 . In this position of the mounting plate the trimmer unit  21  can be rotated about the axis of the collar  31  relative to the mounting blade to selectively adjust either the first blade assembly  32  or the second blade assembly  32  to the operative position as respectively illustrated in  FIGS. 1 and 2  and in  FIGS. 6 and 7 . Downward displacement of the mounting plate  30  and the trimmer unit then causes the drive output pin  26  to be guided into and to operatively engage in the driving section of the slot  42  in the blade driving element  37  or  40  of the trimmer blade assembly  32  or  33  disposed in the operative position. Actuation of the motor  23  then puts the selected trimmer blade assembly into operation whilst the other trimmer blade assembly remains uncoupled from the drive output pin  26  and will remain inactive with the result that battery power is not wasted in unnecessarily driving the blade assembly which is not in the operative position. 
         [0021]    The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm”. 
         [0022]    All documents cited in the Detailed Description of the Invention are, in relevant part, incorporated herein by reference; the citation of any document is not be construed as an admission that it is prior art with respect to the present invention. To the extent that any meaning or definition of a term in this written document conflicts with any meaning of definition of the term in a document incorporated by reference, the meaning or definition assigned to the term in this written document shall govern. 
         [0023]    While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.