Abstract:
The invention concerns the field of writing instruments and in particular a writing instrument comprising a front body with an ergonomic grasping segment asymmetrical relative to a first longitudinal plane, and a rear body asymmetrical relative to a second longitudinal plane. The rear body is capable of rotating relative to the front body about a longitudinal axis corresponding to a line of intersection between the first longitudinal plane and the second longitudinal plane, between a position adapted to gripping with a right hand and a position adapted to gripping with a left hand. The invention also relates to a method of using this writing instrument.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from French Patent Application No. 1258506 filed on Sep. 11, 2012. The disclosure of French Patent Application No. 1258506 filed on Sep. 11, 2012 is hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to the field of writing instruments, and more particularly the ergonomics thereof. 
         [0003]    In the present context &lt;&lt;writing instrument&gt;&gt; means any instrument for manually tracing writing on an adapted surface. Examples of writing instruments are for example pencils, pens, ballpoint or felt-tipped pens, and even adapted styluses. All these writing instruments typically have an elongated form for gripping a front part of the writing instrument between the tips of the thumb and at least one of the index and middle fingers, while a rear part is supported in the grasping angle between the thumb and the index finger to stabilise the writing instrument in the hand. To facilitate this grasping, in particular for school pupils when learning to write, different writing instruments of ergonomic design have been proposed. 
         [0004]    Some of these ergonomic writing instruments, such as for example that disclosed in international patent application WO 01/97653, have a front body with an asymmetrical and ergonomic grasping segment relative to a first longitudinal plane, and an asymmetrical rear body relative to a second longitudinal plane, different to the first longitudinal plane. The grasping segment is adapted to be gripped between the tips of the fingers, while the asymmetry of the rear body better matches the form of the grasping angle, that is, the space between the thumb and the index finger of one hand. 
         [0005]    However, one disadvantage of such ergonomic writing instruments is that due to their asymmetry they can be adapted to usage with the left hand or right hand only. Different instruments must therefore be produced for right-handed and left-handed people, with everything this involves in terms of production and storage costs, as well as disadvantages for users. 
       SUBJECT MATTER AND SUMMARY OF THE INVENTION 
       [0006]    The present invention sets out to overcome these disadvantages. In particular it is the objective of the invention to propose a writing instrument comprising a front body with an ergonomic grasping segment asymmetric relative to a first longitudinal plane, and a rear body asymmetric relative to a second longitudinal plane but which allows use thereof with either the right hand or the left hand. 
         [0007]    In at least one embodiment, this objective is achieved through the fact that the rear body is able to rotate relative to the front body about a longitudinal axis corresponding to a line of intersection between the first longitudinal plane and the second longitudinal plane, between a position adapted to gripping with a right hand and a position adapted to gripping with a left hand. 
         [0008]    Because of these arrangements, the form of the writing instrument can be adapted to ergonomic usage alternatively with the left hand or with the right hand, such that the ergonomics of this instrument no longer conflict with its versatility. 
         [0009]    To separate the index and the thumb on the ergonomic grasping segment, on one side of said first longitudinal plane the latter can have a rib oriented longitudinally and radially projecting relative to a grasping surface of said segment. In particular, this rib can project by at least 2 mm relative to the grasping surface of said segment. This rib can make learning to write easier, helping students to correctly position their fingers on the ergonomic grasping segment. Also, it ensures more stable gripping of the writing instrument. 
         [0010]    The ergonomic grasping segment can also have a stop flange for fingers in the direction of a front end of the front body, for example at a distance of at least 10 mm from this distal end, to ensure a sufficient distance of the fingers relative to the writing surface for the purpose of cleaning the field of vision of the user, which is not only advantageous when students are learning to write, but makes it more comfortable for other users. For better ergonomics, this flange can especially be inclined relative to the longitudinal axis. 
         [0011]    To make gripping of the writing instrument more comfortable, said ergonomic grasping segment can also have a supple grasping surface, preferably overmoulded on the front body. 
         [0012]    To better stabilise the writing instrument in the grasping angle of the hand, the rear body can comprise, on one side of said second longitudinal plane, a concave surface configured to be supported on the base of the index finger. 
         [0013]    It is generally known to equip writing instruments with a retractable writing tip thereby making it possible to retract the writing tip in particular when the instrument is not in use, to avoid staining, drying of the writing tip, etc. Among the different mechanisms used for retracting and extending the writing tip, persons skilled in the art have particular knowledge of mechanisms actuated by relative rotation of the two parts of the writing instrument. 
         [0014]    If the writing instrument comprises a front body and a rear body which can turn relatively relative to each other about a longitudinal axis between a position adapted to gripping with a right hand and a position adapted to gripping with a left hand, this writing instrument could also comprise a writing point, and a retraction and extension mechanism of the writing point, actionable by relative rotation of the front body and the rear body, and configured such that the writing point is retracted into the front body when the rear body and the front body are in an intermediate position between the position adapted to gripping with the right hand and the position adapted to gripping with the left hand, and projecting beyond a front end of the front body when the rear body and the front body are in the position adapted to gripping with the right hand or in the position adapted to gripping with the left hand. In this way, the act of turning the rear body relative to the front body to adapt it to usage with the right hand or the left hand will simultaneously help move the writing point to its projecting position in which the writing instrument can be used. 
         [0015]    In particular, this retraction and extension mechanism may comprise a cam surface secured in rotation with one of the said front and rear bodies, and an element secured in rotation with the other of said front and rear bodies and in contact with said cam surface, the cam surface or said element in contact with the cam surface being capable of moving within the writing instrument along said longitudinal axis and being secured to the writing tip at least in translation along the longitudinal axis. The cam surface therefore allows the conversion of the rotational movement between front and rear bodies to a translational movement of the writing tip along the longitudinal axis. To ensure the same extension movement of the writing tip during rotation in each direction from the said intermediate position, this cam surface may be symmetrical. In addition, to ensure the contact of the second part against the cam surface, the retraction and extension mechanism may also comprise an elastic element arranged so as to push the second part against the cam surface. 
         [0016]    A further aspect of the present invention concerns the assembly of the writing instrument. Since the front body and the rear body will frequently be rotated relative to one another in both directions of rotation about the longitudinal axis throughout the lifetime of the writing instrument, a screw connection does not appear to be adapted. However to provide a robust connection, easy to implement industrially and allowing relative rotation of the front and rear bodies about the longitudinal axis, this writing instrument may further comprise a tubular piece axially joining together i.e. in the direction of the longitudinal axis, the front body and the rear body via elastic snap-fit. Snap-fit (or snap-lock) is a mode of assembling by engagement two parts and elastic deformation (in general local deformation e.g. of a tab). When the two parts are engaged in the snap-fit position, the parts have generally resumed their initial shape and are not elastically deformed anymore (or are less elastically deformed). When the two parts are engaged in each other in the snap-fit position they cooperate with each other so as to resist and even block the relative movements of the said parts in the direction of disengagement (opposite direction to the engaging direction). In the snap-fit position the two parts may also cooperate so as to resist and even block their relative movements in the direction of further engagement, beyond the snap-fit position. In particular, this tubular piece may have shoulders opposite corresponding shoulders of the front and rear bodies for axial retaining of said tubular piece relative to the front and rear bodies. This configuration simplifies the mechanical assembling of the writing instrument, which can therefore be assembled by mere axial engaging of the front and rear bodies, in opposite direction, against the tubular piece. The tubular piece may have some degree of radial elasticity to allow snap-fit, its radial shoulders coming to bear against those of the front body and rear bodies after its elastic return so as to retain the latter axially. This tubular piece may in particular be received in the writing instrument, thereby allowing a non-apparent connection between the front body and the rear body. 
         [0017]    The tubular piece may be secured in rotation with one of the said front and rear bodies and have two rotation stops relative to the other of said front and rear bodies. This part may therefore be used to limit relative rotation between the two bodies. 
         [0018]    To facilitate elastic snap-fit, this elastic part may comprise a longitudinal slot. In this case it may also, in this longitudinal slot, receive a rib secured to one of said front or rear bodies. The longitudinal slot can therefore be used to lock the tubular piece in rotation relative to one of said front or rear bodies. In addition, the rib may be press-fit into the longitudinal slot so as to cause radial expansion of the tubular piece and the engaging of the tubular piece with inner shoulders into at least one of the front or rear bodies to ensure the axial connection between the front and rear bodies via the tubular piece. 
         [0019]    The present invention also concerns a method of use of this writing instrument whereby the ergonomic grasping segment is held between the tips of the thumb and at least one of the index and middle fingers in one same hand, and the rear body is rotated relative to the front body towards the position adapted to gripping with a right hand or towards the position adapted to gripping with a left hand depending on the hand used, so as to ensure the supporting of the rear body in the grasping angle between the index finger and the thumb. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The invention will be more clearly understood and its advantages will emerge more clearly from the following detailed description of an embodiment illustrated by way of non-limiting example. The description refers to the attached diagrams, in which: 
           [0021]      FIG. 1  is a perspective view of a writing instrument according to an embodiment; 
           [0022]      FIG. 2  is a perspective view of the writing instrument of  FIG. 1  in a position adapted to usage with the right hand; 
           [0023]      FIG. 3  is a perspective view of the writing instrument of  FIGS. 1 and 2  in a position adapted to usage with the left hand; 
           [0024]      FIG. 4  is an exploded perspective of the writing instrument of the preceding Figures; 
           [0025]      FIG. 5  is a view in transversal section of the writing instrument of  FIG. 1  in the plane V-V; 
           [0026]      FIG. 6  is a view in longitudinal section of the writing instrument of the preceding Figures in the position of  FIG. 1 ; 
           [0027]      FIG. 7  is a view in longitudinal section of the writing instrument of the preceding Figures in the position of  FIG. 3 ; 
           [0028]      FIG. 8  is an exposed view of a rear body of the writing instrument of the preceding Figures; 
           [0029]      FIG. 9  is a view in longitudinal section of the rear body of  FIG. 8  along the line IX-IX; 
           [0030]      FIG. 10  is a view in longitudinal section of a front body of the writing instrument of the preceding Figures; 
           [0031]      FIG. 11  is a rear view of the front body of  FIG. 10 ; 
           [0032]      FIG. 12  is a plan view of a tubular piece designed to connect said front and rear bodies; 
           [0033]      FIG. 13  is a view in longitudinal section of the tubular piece of  FIG. 12  along the line XIII-XIII; and 
           [0034]      FIG. 14  is a view in longitudinal section of the tubular piece of  FIG. 13  along the line XIV-XIV. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    The general arrangement of a writing instrument  1  is illustrated in  FIGS. 1 to 3 . This writing instrument  1 , which in the illustrated embodiment more specifically takes the form of a ballpoint, comprises a front body  2  and a rear body  3  which can turn relative to each other about a longitudinal axis X. 
         [0036]    The front body  2  comprises two parts: an ergonomic grasping segment  4  and an end part  5  forming a distal end of this front body  2 . The segment  4  is asymmetrical relative to a longitudinal plane A, as it has especially, on a single side of this longitudinal plane A, a radially projecting rib  6 . During use of the instrument  1 , this rib  6  operates as a key to make gripping easy by separating the thumb from the index finger. The segment  4  also has a radially projecting flange  7 , opposing the fingers in the direction of the front end of the front body  2 , and in this way also making it easier for the index and middle fingers and thumb to grip round the segment  4 . In the embodiment illustrated, this flange  7  is inclined in an axial direction for better gripping comfort of the segment  4 . The segment  4  also has an overmoulded grasping surface  8 , made of material suppler than the rest of the segment  4 . This grasping surface  8 , slightly concave, can also have a texture in relief or projecting for securer gripping. The end part  5  has a conical external surface and a thread complementary to an internal thread inside the segment  4  for fixing it to the front end of the segment  4 . 
         [0037]    The rear body  3  is asymmetrical relative to a longitudinal plane B, as it has especially, on a single side of this longitudinal plane B, a concave support surface  9  to facilitate support of the rear body on the base of the index finger in the grasping angle of the hand of the user. However, depending on whether the hand being used is the right hand or the left hand, the index finger will be to one side or the other of the rib  6 . To adapt the instrument  1  to usage with the right hand or the left hand, the rear body  3  can turn relative to the front body  2 , about the longitudinal axis X, between the position illustrated in  FIG. 2 , which is adapted to use with the right hand with the surface concave  9  to the right of the rib  6 , and the position illustrated in  FIG. 3 , which is adapted to use with the left hand with the concave surface  9  to the left of the rib  6 . 
         [0038]    Between these two positions, the longitudinal planes A and B turn relative to each other about their line of intersection along the longitudinal axis X. As a consequence, the instrument  1  can also adopt the intermediate position illustrated in  FIG. 1 , between the positions of  FIGS. 2 and 3 , in which the longitudinal plane A of the front body  2  coincides with the longitudinal plane B of the rear body  3 . In the embodiment illustrated, the instrument  1  comprises a retractable writing point  10 , and a retraction and extension mechanism of this writing point  10  which is actionable by relative rotation of the front body and rear body  2 ,  3 , and configured such that the writing point  10  is retracted into the front body  2  when the front and rear bodies  2 ,  3  are in the intermediate position illustrated in  FIG. 1 , and projecting beyond the front end of the front body  2  when the front and rear bodies  2 ,  3  are in the positions illustrated in  FIGS. 2 and 3 . The angle of rotation a of the rear body  3  relative to the front body  2 , between the intermediate position illustrated in  FIG. 1  and each of the positions illustrated in  FIGS. 2 and 3  can be 120°, for example. 
         [0039]      FIG. 4  illustrates an exploded perspective of the instrument  1 , showing its internal components. In this way, inside the instrument  1  illustrated the latter contains an elastic element  11  in the form of a helical spring, a standard ballpoint refill  12 , a slide  13  and a tubular piece  14 . The refill  12  comprises the writing point  10  and an ink tank  15  and is received inside the slide  13 , which is open to the front and at least partially closed to the rear. The elastic element  11 , supported against the internal face of the end part  5  at the front end of the front body  2 , presses the refill  12  against the bottom of the slide  13 . 
         [0040]    As is evident from  FIG. 5 , which is a transversal section of the instrument  1  along the plane V-V of  FIG. 1 , ribs  16 ,  17  on the internal surface of the front body  2  cooperate with grooves  18 ,  19  on the external surface of the slide  13 , to have the slide  13  connected to the front body  2  in rotation about the longitudinal axis X, and enable axial displacement of the slide  13  along the longitudinal axis X. 
         [0041]    The slide  13  also has a finger  20  on its external surface. As is evident from  FIG. 6 , this finger  20  is in contact with a cam surface  21  formed in the internal surface of the rear body  3  and with it constitutes an extension and retraction mechanism of the writing point  10 . The cam surface  21  has a helical contour capable of pushing the finger  20  to the front when the rear body  3  turns in one or the other direction from the intermediate position illustrated in  FIG. 1 . As the finger  20  is connected to the writing point  10  via the slide  13  and the refill  12 , rotation of the rear body  3  in one or the other direction about the longitudinal axis X relative to the front body  2  will cause displacement of the writing point  10  between its retracted position, illustrated in  FIG. 6 , and its writing position, illustrated in  FIG. 7 . In the retracted position illustrated in  FIG. 6  the writing point  10  is received in the front body  2 , and more specifically, in the end part  5  in the illustrated embodiment. In the writing position, illustrated in  FIG. 7 , the writing point  10  projects beyond the front end of the front body  2 . 
         [0042]    The cam surface  21  is more clearly visible in  FIGS. 8 and 9 , respectively illustrating a partial cutaway of the rear body  3 , and a partial longitudinal section along a plane IX-IX perpendicular to the plane B. This shows in particular how the cam surface  21  is symmetrical relative to the longitudinal plane B so as to actuate the same extension movement of the writing point  10  when the rear body  3  is turned in one or the other direction from the intermediate position illustrated in  FIGS. 3 and 6 . Also, on each side this cam surface has a notch  22  at the end designed to hook the finger  20  and in this way block the writing point  10  in its writing position. However, the angle of inclination of the inner edge  23  of each notch  22  is such that it offers only slight resistance to rotation of the rear body  3  when the user turns it, relative to the front body  2 , from this position to its intermediate position to retract the writing point  10  into the front body  2 . 
         [0043]    The rear body  3  also comprises, on its internal surface, radial shoulders  24  and a longitudinal rib  25  designed to cooperate with the tubular piece  14 . As illustrated in  FIGS. 10 and 11 , on its rear end the segment  4  also has lips  26 ,  27  designed to cooperate with the tubular piece  14 , as well as a rotation stop  28 . This tubular piece  14  is illustrated in greater detail in  FIGS. 12 to 14 . These Figures show how the latter has a longitudinal slot  29 . On the one hand, because of this longitudinal slot, the tubular piece  14  is more easily deformable elastically in a radial plane. But this slot  29  is also capable of taking up the rib  25  of the rear body  3  so as to cooperate with the latter to have the tubular piece  14  connect to the rear body in rotation, as illustrated in particular in  FIG. 5 . The width of the slot  29  when the tubular piece  14  is free of stress is however less than that of the rib  25 , such that when the rib  25  is introduced to the slot  29 , it causes radial expansion of the tubular piece  14 .  FIGS. 12 to 14  also show how the tubular piece  14  has radial shoulders  30  on its external surface. As illustrated in particular in  FIGS. 6 and 7 , these radial shoulders  30  in the tubular piece  14 , which is dilated radially by the press-fit of the rib  25  in the slot  29 , cooperate with the radial shoulders  24  to hold the tubular piece  14  in the rear body  3  by elastic snap-fit. The rear edge  31  of the tubular piece  14  also forms a radial shoulder against which the lips  26 ,  27  of the segment  4  are supported accordingly to axially hold the front body  2  by elastic snap-fit, without however preventing it from rotating relative to the tubular piece  14  and the rear body  3 . However, as illustrated in  FIGS. 12 to 14 , the tubular piece  14  also has axial protuberances on its front edge  32  forming stops  33  in rotation, which butt against the corresponding stop  28  of the front body  2  to limit the relative rotation of the rear body  3  relative to the front body  2 . In this way, the tubular piece  14  axially connects the front body  2  and the rear body  3 , and limits their relative rotation between the positions illustrated in  FIGS. 2 and 3 . 
         [0044]    During assembly of the writing instrument  1 , the slide  13  is introduced at the rear of the segment  4 , and because of its radial elasticity the tubular piece  14  is threaded onto the rear end of the segment  4  until its rear edge  31  can be supported on the front faces of the lips  26 . Next, the rear end of the segment  4 , with the tubular piece  14  and the slide  13 , is introduced into the rear body  3 , with the slot  29  of the tubular piece  14  aligned with the rib  25  of the rear body  3 , and the grooves  18 ,  19  of the slide  13  aligned with the corresponding ribs  16 ,  17  on the internal surface of the segment  4 . Due to the radial elasticity of the tubular piece  14 , and the inclination of the surfaces  34  and  35  respectively in the tubular piece  14  and the rear body  3 , the rear end of the segment  4  and the tubular piece  14  can enter the front end of the rear body until the forced engagement of the rib  25  in the slot  29  causes radial dilation of the tubular piece  14 , such that its radial shoulders  30  are supported on the radial shoulders  24  of the rear body  3  accordingly to block axially the segment  4  relative to the rear body  2 . The refill  12  and the spring  11  can then be introduced into in the instrument  1  via the front end of the segment  4  which can then be closed with the end part  5  to complete the front body  2  and the instrument  1 . Subsequently, the refill  12  could easily be replaced by unscrewing the end part  5  without having to separate the entire front body  2  from the rear body  3 . 
         [0045]    Although the present invention has been described in reference to a specific embodiment, it is evident that various modifications and changes could be made to these examples without departing from the general scope of the invention such as defined by the claims. Consequently, the description and the diagrams must be considered more illustratively than restrictively.