Patent Publication Number: US-11376885-B2

Title: Multifunction writing instrument

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
     This application is a National Stage Application of International Application No. PCT/EP2019/060185, filed on Apr. 18, 2019, now published as WO2019/202120 and which claims priority to French Application No. FR1853468, filed on Apr. 19, 2018. 
     TECHNICAL FIELD 
     The present disclosure relates to a multifunction writing instrument. It should be recalled that a multifunction writing instrument is a writing instrument having a plurality of writing elements, each writing element being usable selectively. 
     BACKGROUND 
     Known multifunction writing instruments are not always very easy to manipulate when it is desired to use a writing tip that is different from the tip that is being used. There therefore exists a need in this sense. 
     SUMMARY 
     An embodiment provides a multifunction writing instrument comprising a body extending along an axial direction and housing two or more writing elements, each writing element including a writing tip, a selector device configured to select one writing element from among the two or more writing elements, a retraction device configured to move a selected writing element between a writing position in which the writing tip of the selected writing element projects from the body and a retracted position in which the writing tip of the selected writing element is retracted, and a return device configured to bring one of the writing elements from the writing position back to the retracted position when the selector device is activated while another of the writing elements is in the writing position. 
     In general manner, it can be understood that the writing instrument extends in an axial direction that corresponds to the direction of the axis of the body (i.e. the axial direction of the body). A radial direction is a direction perpendicular to the axis of the body, and a circumferential or azimuth direction corresponds to a direction describing a ring around the axial direction. Finally, unless specified to the contrary, the adjectives “inside” and “outside” or “inner” and “outer” are used with reference to a radial direction such that an inner element (i.e. a radially inner element) is closer to the axis of the body than is an outer element (i.e. a radially outer element). 
     Below, and unless specified to the contrary, the term “writing instrument” is used to mean “multifunction writing instrument”. 
     Naturally, the writing instrument may present two or more writing elements. Below, and unless specified to the contrary, the term “the writing elements” means “the at least two writing elements”. 
     In the meaning of the present disclosure, a writing element is formed by any element that has a writing tip. By way of example, the writing tip may be a felt tip, a ball or other point, a graphite lead, a mechanical pencil lead, a chalk, any other means suitable for writing on a substrate, or an (active or passive) endpiece configured to co-operate with a touch screen, e.g. a capacitive, resistive, inductive, infrared, optical, electrostatic, etc. screen. For example, if the writing element comprises a ballpoint, it also comprises an ink reservoir. In another example, if the writing element comprises a mechanical pencil, it also comprises a lead propelling mechanism and a lead reservoir. Below, and unless specified to the contrary, it is assumed that the writing tip of any writing element is carried by a writing head, the writing tip possibly being stationary (e.g. a ballpoint) or movable (e.g. a mechanical pencil lead) relative to the writing head. 
     The body is naturally hollow and configured to receive the writing elements. The body thus presents an inside and an outside. 
     It can be understood that the selector device serves to select a writing element, while the retraction device serves to actuate the writing element. Thus, in the meaning of the present disclosure, the term “select a writing element” is used to mean “configure the writing instrument so that the writing element can co-operate with the retraction device” in satisfactory manner. Naturally, it should be understood that the selector device serves to select no more than one writing element at a time. For example, in intermediate positions, the selector device co-operates with a plurality of writing elements, whereas the selector device co-operates with only one writing element when a writing element is selected. In a first a variant, when a writing element is selected by means of the selector device, the head of the writing element may remain retracted within the body, in which case the retraction device can be used to cause the writing head to move into and out from the body. This first variant is appropriate both for writing elements having a fixed writing tip and for writing elements having a movable writing tip. In a second variant, that is particularly appropriate for writing elements having a movable writing tip, when a writing element is selected by means of the selector device, the head of the writing element extends out from the body, in which case the retraction device serves solely to cause the writing tip to move into and out from the writing head. Naturally, within the writing instrument, one writing element may be configured as the first variant while another writing element may be configured as the second variant. In other words, the first and second variants can coexist within a single writing instrument. 
     It can be understood that the retraction device serves to move the writing tip of the selected writing element between a writing position and a retracted position. For example, when the writing element has a fixed writing tip, e.g. such as a ballpoint mounted on a head, itself mounted on an ink reservoir, when in the retracted position the writing tip is inside the body, whereas in the writing position the writing tip extends outside the body. In another example, when the writing tip of the writing element is movable, e.g. such as a lead carried by a head of a mechanical pencil mechanism, then in the retracted position the lead may be inside the mechanical pencil, it being possible for the head of the mechanical pencil either to be inside the body or else to extend outside the body, or else the lead may extend outside the head of the mechanical pencil while the head is inside the body, so that the lead does not project from the body. Naturally, in the writing position, such a movable writing tip extends outside the body, the head of the writing element possibly being outside or inside the body. In other words, for writing elements having a movable writing tip, the retraction device may serve solely to cause the writing tip to move into and/or out from the head of the writing element (e.g. in order to propel the lead of a mechanical pencil, and allow it to return into the mechanical pencil when the jaws of the pencil mechanism are un-clamped). 
     Thus, the user firstly selects the writing element that is to be used by means of the selector device, and secondly moves the writing tip between a retracted position and a writing position by means of the retraction device. 
     The return device serves to bring a writing element from the writing position back to the retracted position when it is desired to select a writing element other than the writing element in the writing position. Thus, by actuating the selector device, the return device is actuated. In other words, the return device is coupled with the selector device, at least while a writing element is in the writing position. This makes manipulating the writing instrument particularly easy for the user. Specifically, the user can select a writing element without worrying about the position of the already-selected writing element. Furthermore, in some variants, the selector device can be actuated only if all of the writing elements are in the retracted position, otherwise there is a risk of bringing the various mechanisms of the retraction device and/or of the selector device out of alignment, or indeed of blocking or damaging these mechanisms. For these variants of the writing instrument, the return device thus also serves to avoid any blocking, damage, and/or loss of alignment of the mechanisms of the selector device and of the retraction device. 
     In some embodiments, the body comprises a front portion and a rear portion, the front portion and the rear portion being rotatably movable relative to each other about the axial direction, the selector device comprising a cam rotatably coupled with the rear portion and configured to co-operate with the writing elements while the writing elements are rotatably coupled with the front portion, the retraction device comprising a ratchet mechanism comprising a rotary cam and a plunger cam, the plunger cam being rotatably coupled with the rear portion, the rotary cam being rotatably coupled with the front portion when a writing element is in the writing position, while the rotary cam is free to turn relative to the front portion when all of the writing elements are in the retracted position, whereby the rotary cam turns so as to release the plunger cam in the axial direction relative to the rotary cam when the selector device is activated while a writing element is in the writing position. 
     It can be understood that the front portion is turnable relative to the rear portion (and vice versa) about the axial direction (i.e. in the circumferential direction). 
     While the front portion is turning relative to the rear portion, the cam of the selector device is caused to turn relative to the front portion by the rear portion, and depending on its azimuth position relative to the writing elements, the cam co-operates with no, or with one or another or several of the writing elements. 
     The plunger cam is rotatably coupled with the rear portion, and this applies regardless of the configuration of the writing instrument. The rotary cam is rotatably coupled with the front portion only when a writing element is in the writing position. Thus, when it is desired to actuate the selector device by turning the front portion relative to the rear portion (or vice versa), and if a writing element is in the writing position, then the rotary cam, which is rotatably coupled with the front portion, also turns relative to the rear portion. Since the plunger piston is rotatably coupled with the rear portion, the rotary cam turns relative to the plunger piston, thereby having the effect of releasing the plunger cam from the rotary cam (and vice versa) and allowing the writing element to return into the retracted position. Such a structure contributes to making the writing instrument easy to use. 
     In some embodiments, the front portion presents an axially extending rod, the rod including at least one axial groove or at least one axial rib, the rotary cam being engaged around the rod and presenting respectively at least one axial rib or at least one axial groove, the axial rib and the axial groove being engaged with each other when a writing element is in the writing position, and being disengaged from each other when all of the writing elements are in the retracted position. 
     Such an axial rib/groove system is simple and compact, and enables the front portion and the rotary cam to be coupled/uncoupled for turning together in a manner that is reliable, efficient, and easy to use. 
     In some embodiments, the cam of the selector device and the plunger cam of the ratchet mechanism are formed by a single part. 
     Such a configuration is compact and enables the number of different parts within the writing instrument to be reduced. This simplifies the overall structure of the writing instrument, facilitates assembling it, and serves to increase its reliability, thereby contributing indirectly to making the writing instrument easy for the user to manipulate. 
     In some embodiments, the plunger cam includes an annular portion, the rotary cam being arranged radially inside the annular portion. 
     Such a configuration is compact and saves space, thereby enabling writing elements of greater capacity to be received within the writing instrument. 
     In some embodiments, the rotary cam is prevented from moving in the axial direction relative to the front portion when all of the writing elements are in the retracted position, while the rotary cam is movable along the axial direction relative to the front portion when a writing element is in the writing position. 
     For example, depending on whether one writing element is in the writing position or all of the writing elements are in the retracted position, the space between two axial shoulders (i.e. transversely to the axial direction) in which the rotary cam is located is of greater or smaller size, thereby authorizing or blocking axial movement of the rotary cam. 
     The rotary cam being blocked axially when all of the writing elements are in the retracted position enables rotation of the rotary cam to be guided better while actuating the retraction device in order to bring a writing element into the writing position. Conversely, when a writing element is in the writing position, the fact that the rotary cam is axially movable enables it to become disengaged from the front portion during turning of the front portion relative to the rear portion, e.g. by decoupling a system of teeth or of grooves and ribs. Thus, the rotary cam is rotatably coupled with the front portion over only a fraction of the total rotary stroke of the front portion relative to the rear portion. This makes it possible to sequence the actuation of the various devices, i.e. to begin by actuating the return device in order to release the rotary cam from the plunger cam and allow the writing element in the writing position to return towards the retracted position, and subsequently to continue solely with the action on the selector device in order to select another writing element. Such a configuration is particularly well adapted to variants in which the selector device can be actuated only when all of the writing elements are in the retracted position. 
     In some embodiments, the rotary cam is rotatably coupled with the plunger cam when all of the writing elements are in the retracted position. 
     For example, the coupling may be obtained by engaging teeth of the plunger cam with teeth of the rotary cam. Such coupling makes it possible, while actuating the selector device, to conserve proper alignment of the elements of the mechanism of the retraction device. Thus, when the front portion is turned relative to the rear portion in order to select a writing element, it is certain that the alignment of the two cams of the retraction device will be conserved, whereby the retraction device is perfectly operational regardless of the position of the selector device, in particular regardless of which writing element is selected. This makes the writing instrument more reliable and contributes to making it easy to manipulate. 
     In some embodiments, the cam of the selector device is configured to co-operate with cam followers of the writing elements, each cam follower being received to slide axially in an axial guide of the front portion. 
     It can thus be understood that the writing elements can slide axially within an axial guide, and thus within the front portion. Each guide serves to keep the writing element that it receives in position relative to the front portion, both in the radial direction and in the circumferential direction. This facilitates interaction between the cam of the selector device and the writing elements, making the writing element gentler and easier to use. 
     In some embodiments, at least one writing element is a mechanical pencil, the retraction device being usable to propel the lead of the mechanical pencil when the mechanical pencil is in the writing position. 
     Specifically, the writing instrument of the present disclosure is particularly well adapted to mechanical pencils. 
     In some embodiments, the mechanical pencil presents a writing head that is configured to carry the lead, the lead forming a writing tip, the writing head projecting from the body when the mechanical pencil is selected by means of the selector device. 
     It can thus be understood that the writing head projects from the body as soon as the mechanical pencil has been selected. As described above, in such a configuration, the retraction device serves only to propel the lead, which in the meaning of the present disclosure is considered as moving the writing tip, from a retracted position to a writing position. A writing device including such a mechanical pencil is particularly easy to use. 
     Naturally, in a variant, the set of writing elements (i.e. including a mechanical pencil as defined above) may include a mechanical pencil that presents a writing head configured to carry the lead, the lead forming a writing tip, the mechanical pencil being such that when it is selected by means of the selector device, it is movable between an extended position in which the writing head projects from the body and a retracted position in which the writing head is brought into the body by the retraction device, and when it is in the extended position, the retraction device serves to enable the lead to be propelled by being moved only partially compared with the movement needed by the retraction device in order to cause the mechanical pencil to pass from the extended position to the retracted position. 
     It can thus be understood that in this variant, the head does not project from the body when the mechanical pencil is selected (i.e. it is in the retracted position). It is then necessary to actuate the retraction device in order to move the head out from the body. Once the head is located outside the body (i.e. in the extended position), actuating the retraction device only partially serves to propel the lead, whereas actuating the retraction device fully serves to cause the head to return back inside the body, i.e. into the retracted position. A writing device having such a mechanical pencil enables the head of the mechanical pencil to be located inside the body when it is selected, thereby serving to protect it. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter of the present disclosure and its advantages can be understood better on reading the following detailed description of various embodiments that are given as non-limiting examples. The description refers to the accompanying sheets and figures, in which: 
         FIG. 1  shows an embodiment of a writing instrument seen in perspective; 
         FIG. 2  shows the  FIG. 1  writing instrument in an exploded view; 
         FIGS. 3A and 3B  show the various steps for selecting a writing element; 
         FIGS. 4A to 4F  show the various steps for causing the writing element selected in  FIG. 3B  to pass from the retracted position to the writing position; 
         FIGS. 5A to 5E  show the variant steps for causing the writing element to go from the writing position as shown in  FIG. 4F  to the retracted position by using the retraction device; and 
         FIGS. 6A to 6C  show the various steps for causing the writing element to pass from the writing position as shown in  FIG. 4F  to the retracted position, by means of the return device, when the selector device is actuated. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a multifunction writing instrument  10  extending along an axial direction X and comprising a body  12  that, in this example, houses two writing elements  14 A and  14 B, namely a mechanical pencil and a ballpoint element. Naturally, in a variant, the writing instrument could have more than two writing elements. In another variant, both writing elements could be identical, or indeed could be of kinds other than a mechanical pencil or a ballpoint element. In this example, the mechanical pencil  14 A comprises a writing head  14 A 3 , a lead-propelling mechanism  14 A 4 , and a lead reservoir  14 A 5 . A lead (or writing tip)  15 A is carried by the head  14 A 3 . The writing element  14 B has a writing head  14 B 3  comprising a ballpoint (or writing point)  15 B, and an ink reservoir  14 B 5 . 
     In this example, the body  12  comprises a front portion  12 A, and a rear portion  12 B. The front portion  12 A comprises a first portion  12 A 1  and a second portion  12 A 2 , the second portion  12 A 2  forming an intermediate portion between the first portion  12 A 1  and the rear portion  12 B. The first portion  12 A 1  and the rear portion  12 B are mounted respectively on the second portion  12 A 2  so as to be turnable relative to each other about the axial direction X (i.e. movable in the circumferential direction C). In this example, the first portion  12 A 1  and the second portion  12 A 2  are coupled together in rotation (e.g. being assembled together by screw-fastening tightened to a certain torque, or else by clipping with a coupling lug), while the rear portion  12 B is turnable about the axial direction X relative to the second portion  12 A 2  (e.g. by axial clip-fastening using annular portions in relief, permitting turning about the axial direction X). The front and rear portions  12 A and  12 B are thus turnable relative to each other about the axial direction X. In  FIG. 1 , the first portion  12 A 1  is drawn transparently, so that the writing elements can be seen. Naturally, the various elements of the body  12 , and in particular the first portion  12 A 1 , may be transparent or opaque, so as to enable the user to see the inside of the writing instrument  10 , or so as to prevent the user from seeing the inside. The writing elements  14 A and  14 B are carried by the second portion  12 A 2 . The second portion  12 A 2  is rotatably coupled about the axial direction X with the first portion  12 A 1 , and the writing elements  14 A and  14 B are rotatably coupled with the entire front portion  12 A. 
     The writing instrument  10  is described below in greater detail with reference to  FIG. 2 . The writing instrument  10  comprises a selector device  18 , a retraction device  20 , and a return device  22  (see also  FIG. 6A ). 
     The selector device  18  comprises a cam  18 A configured to co-operate in abutment with the writing elements  14 A and  14 B, and more particularly in this example with cam followers  14 A 1  and  14 B 1  of the elements  14 A and  14 B. The cam  18 A is received in a slideway  12 B 1  of the rear portion  12 B enabling the cam  18 A to slide along the axial direction X relative to the rear portion  12 B and to be rotatably coupled about the axial direction X with the rear portion  12 B. Furthermore, in this example, the rear portion  12 B presents an inside shoulder  12 B 3  (which is naturally coupled to the rear body  12 B) that extends the profile of the cam  18 A when the retraction device  20  is in a configuration corresponding to the retracted position of the writing elements. Thus, by means of the cam  18 A and the shoulder  12 B 3 , the selector device  18  presents a closed cam profile of oval shape, the plane of the oval sloping relative to the axial direction X. In this example, the cam  18 A extends over an angular amplitude of more than 180° (one hundred eighty degrees of angle) and can co-operate simultaneously with both writing elements when changing the writing element that is selected. In other words, in this example, the writing elements  14 A and  14 B are arranged at 180° relative to each other (i.e. they are diametrically opposite within the writing instrument  10 ), and when it is desired to select a writing element other than the already-selected writing element, the cam  18 A occupies intermediate positions in which it co-operates simultaneously with both writing elements  14 A and  14 B. Nevertheless, when a writing element is selected, the cam  18 A co-operates with that writing element only, and not with the other. 
     The rear portion  12 B presents an inside shoulder  12 B 2  (which is naturally coupled to the rear portion  12 B) that is set back rearwards relative to the writing instrument (i.e. towards the end  12 E of the body  12  as shown in  FIG. 1 ), which shoulder does not co-operate with the writing elements  14 A and  14 B, but only with a washer  26  in the writing position. 
     By means of the cam profile formed by the cam  18 A of the selector device  18 , the rear portion  12 B can turn through 360° (three hundred sixty degrees of angle) relative to the front portion  12 A about the axial direction X, in one direction or the other, selecting in succession the writing element  14 A and the writing element  14 B. In a variant, the relative rotary stroke between the front portion  12 A and the rear portion  12 B could be less than 360°, in which case it is necessary to turn in one direction to select one writing element and in the opposite direction to select the other writing element. 
     While the front portion  12 A is turning relative to the rear portion  12 B (or vice versa) in order to select a writing element, the cam  18 A co-operates with the cam followers  14 A 1  and  14 B 1  by bearing against them in the circumferential and axial directions C and X. In order to ensure that the writing elements  14 A and  14 B remain in position within the second portion  12 A 2  of the front portion  12 A, the second portion  12 A 2  has two guides  12 A 21 , in this example axial grooves  12 A 211  leading to axial through holes  12 A 212 . The cam followers  14 A 1  and  14 B 1  are slidably received within the grooves  12 A 211 , while the remaining portions of the writing elements  14 A and  14 B extend in and on either side of the holes  12 A 212 . Compression springs  14 A 2 ,  14 B 2  are arranged respectively between the cam followers  14 A 1 ,  14 B 1  and the second portion  12 A 2 , within the grooves  12 A 211 . These springs are useful in particular when using the retraction device  20  as described below. It should be observed that the grooves  12 A 211  are closed in the axial direction X at their rear ends, remote in the axial direction from the holes  12 A 212 , by means of respective shoulders  12 A 211 A limiting the rearward axial stroke of the writing elements  14 A and  14 B. Each shoulder  12 A 211 A thus blocks the stroke of a writing embodiment  14 A or  14 B when the cam  18 A is not co-operating with the writing elements. The shoulder  12 A 211 A of each guide is of a shape that is complementary to the cam followers  14 A 1  and  14 B 1 , and it co-operates with the cam followers  14 A 1  and  14 B 1  as a result of being complementary in shape. 
     The writing elements  14 A and  14 B are thus held and guided along the axial direction by the guides  12 A 21 , in particular when the cam  18 A is engaged with them. When the cam  18 A co-operates with a writing element, the writing element is pushed towards the front of the writing device (i.e. towards the end  12 D of the body  12  in  FIG. 1 ). This corresponds to the position of the writing element  14 A in  FIG. 3B . When the cam  18 A does not co-operate with a writing element, the writing element is pushed towards the rear of the writing device (i.e. towards the rear end  12 E of the body  12  in  FIG. 1 ) by its spring, so that the cam follower co-operates in abutment against the shoulder  12 A 211 A of the guides  12 A 21 . This corresponds to the position of the writing element  14 B in  FIG. 3B . In an intermediate position, the cam  18 A co-operates with both cam followers  14 A 1  and  14 B 1 . This corresponds to the position shown in  FIG. 3A . 
     In this example, it should be observed that the rear portion  12 B may be separated from the second portion  12 A 2  of the front portion  12 A to enable the writing elements  14 A,  14 B to be removed. Specifically, the front portions of the writing elements  14 A and  14 B extending in the first portion  12 A 1  of the front portion  12 A can slide freely within the holes  12 A 212 , so the writing elements can be removed in order to be replaced. In a variant, the second portion  12 A 2  comprises two distinct parts, namely a first part forming the holes  12 A 212  and a second part forming the grooves  12 A 211 . The first part is mounted to turn with the first portion  12 A 1  (i.e. free to rotate about the axial direction X, but coupled in translation), e.g. by means of a clip-fastening. The second part is mounted to turn with the rear portion  12 B (i.e. they are free to turn about the axial direction X, but coupled in translation), e.g. by means of clip-fastening. The first portion  12 A 1  is mounted on the second part by screw-fastening, the first part and the second part being rotatably coupled together about the axial direction X. By unscrewing the first portion  12 A 1  from the second part, the first part is removed simultaneously, thereby enabling the writing elements to be removed directly from the grooves that are opened axially in this way. This variant makes it easy to replace the writing elements. 
     The retraction device  20  is a ratchet mechanism comprising a rotary cam  20 A and a plunger cam  20 B. The plunger cam  20 B is integral with the cam  18 A of the selector device  18 . The plunger cam  20 B is moved in translation about the axial direction X by a button  23  arranged at the rear end  12 E of the body  12 . In this example, the button  23 , the plunger cam  20 B, and the cam  18 A of the selector device  18  together form a single part  19 . 
     The ratchet mechanism  20  co-operates with the writing elements  14 A and  14 B via the cam  18 A of the selector device  18 , thereby enabling each of the writing elements to be moved between a retracted position and a writing position. When the cam  18 A is engaged with a writing element, the spring  14 A 2  or  14 B 2  of the writing element compresses the ratchet mechanism  20 , thereby enabling it to be used. 
     The rotary cam  20 A is generally in the shape of a ring having its axis coinciding with the axial direction X and capable of turning about the axial direction X. On its outside surface, this ring carries a first series of teeth  20 A 1  configured to co-operate with the plunger cam  20 B, and on its inside surface it carries a second series of teeth  20 A 2  configured to co-operate with the front portion  12 A of the body  12 , and more particularly in this example with the second portion  12 A 2 . 
     The first series of teeth  20 A 1  comprises rear teeth  20 A 1 A and front teeth  20 A 1 B. The rear teeth  20 A 1 A are of triangular sawtooth shape with one side parallel to the axial direction X and another side that slopes relative to the axial direction, and they form a series comprising in succession in the circumferential direction both a tooth  20 A 1 A 1  that is long in circumferential direction and also a tooth  20 A 1 A 2  that is short in the circumferential direction. The sloping faces of the long teeth  20 A 1 A 1  and of the short teeth  20 A 1 A 2  face towards the same side. The rear teeth  20 A 1 A 1  and  20 A 1 A 2  in each pair are spaced apart circumferentially by an axial passage  21 A. The face parallel to the axial direction of the long tooth  20 A 1 A 1  and the face sloping relative to the axial direction of the short tooth  20 A 1 A 2  face towards the passage  21 A. In this example, there are four pairs of rear teeth  20 A 1 A 1  and  20 A 1 A 2  that are regularly distributed in the circumferential direction, with a passage  21 A being formed between each adjacent pair of teeth. The front teeth  20 A 1 B are of trapezoidal shape and they are all similar, being regularly distributed circumferentially and spaced apart by passages  21 A. Each tooth  20 A 1 B presents a face parallel to the axial direction X and lying axially in line with the face of a long tooth  20 A 1 A 1  that is parallel to the axial direction. Each tooth  20 A 1 B presents a face that is perpendicular relative to the axial direction and that forms an axial shoulder. Finally, each tooth  20 A 1 B presents a face that slopes relative to the axial direction, facing a passage  21 A. The sloping face of each tooth  20 A 1 B is arranged on the same side as the sloping face of a short tooth  20 A 1 A 2 . In other words, the sloping faces of the teeth  20 A 1 B and the teeth  20 A 1 A 2  face a passage  21 A in the same circumferential direction. In this example, there are four teeth  20 A 1 B. In this example, a single radial projection forms a tooth  20 A 1 A 1 , a tooth  20 A 1 A 2 , and a tooth  20 A 1 B. In other words, the outside face of the rotary cam  20 A has four radial projections forming the first series of teeth  20 A 1 . 
     The second series of teeth  20 A 2  comprises rear teeth  20 A 2 A and front teeth  20 A 2 B. The rear teeth  20 A 2 A are trapezoidal in shape and they are spaced apart by axial passages  21 B, while the front teeth  20 A 2 B are square in shape and they are spaced apart by the same axial passages  21 B. Each rear tooth  20 A 2 A presents a face parallel to the axial direction X, a face perpendicular to the axial direction X and forming an axial shoulder, and a face sloping relative to the axial direction and facing a passage  21 B. The slope of the inclined face of each tooth  20 A 2 A 1  slopes on the same side as the slope of the teeth  20 A 1 A 1  and  20 A 1 A 2 . Each front tooth  20 A 2 B presents two faces parallel to the axial direction X and one face perpendicular to the axial direction X, forming an axial shoulder. In this example, there are four rear teeth  20 A 2 A and four front teeth  20 A 2 B. In this example, a single radial projection forms one rear tooth  20 A 2 A and one front tooth  20 A 2 B. In other words, the inside face of the rotary cam  20 A has four radial projections forming the second series of teeth  20 A 2 . 
     The rotary cam  20 B is engaged on an axial rod  12 A 22  of the second portion  12 A 2  of the front portion  12 A of the body  12 . This rod  12 A 22  has teeth  12 A 221 , and in this example it has four teeth  12 A 221  that are uniformly distributed and spaced apart around the circumferential direction on the rod  12 A 22 . These teeth  12 A 221  are in the form of axial ribs. These teeth  12 A 221  are configured to co-operate with the second series of teeth  20 A 2  of the rotary cam  20 A and they can engage in and slide along the passages  21 B, which are in the form of axial grooves. This system of teeth  12 A 221  and  20 A 2  forms the return system  22  (see also  FIG. 6A ). 
     It should be observed that the rod  12 A 22  extends from a base  12 A 23  that forms a shoulder limiting axial movement towards the front of the rotary cam  20 A. Since the rotary cam  20 A can turn about the rod  12 A 22  (when it is not engaged with the teeth  12 A 221 ), the base  12 A 23  is provided with four distinct studs  12 A 23 A that are regularly distributed around the circumferential direction in order to limit friction between the base  12 A 23  and the rotary cam  20 A. 
     The plunger cam  20 B is in the form of an annular portion of axis that extends along the axial direction X and that receives the rotary cam  20 A. In other words, the rotary cam  20 A is arranged radially inside the plunger cam  20 B. 
     The plunger cam  20 B presents two pairs of teeth  20 BA that are diametrically opposite. Each pair of teeth  20 BA presents a rear tooth  20 BA 1  and a front tooth  20 BA 2 . Each tooth is in the form of an axial rib, the rear and front teeth  20 B 1  and  20 B 2  of a given pair  20 BA being offset from each other in the axial direction X and in the circumferential direction C. Each pair of teeth  20 BA is configured to co-operate with the first series of teeth  20 A 1  of the rotary cam  20 A. In particular, the front teeth  20 BA 2  co-operate with the front teeth  20 A 1 B and can engage in and slide along the passages  21 A, while the rear teeth  20 BA 1  co-operate with the rear teeth  20 A 1 A. 
     The single part  19  forming the cam  18 A of the selector device, the plunger cam  20 B, and the button  23  is engaged on the rod  12 A 22 . A spring  24  and the washer  26  are also engaged on the rod  12 A 22  between the part  19  and the rotary cam  20 A. The button  23  is hollow and receives the rear end of the spring  24 . The front end of the spring  24  co-operates axially with the rotary cam  20 A via the washer  26 . The function of the washer  26  is to limit friction between the rotary cam  20 A and the spring  24  when the rotary cam  20 A turns. The washer  26  is free to move axially on the rod  12 A 22 . The spring  24  and the washer  26  are arranged radially inside the plunger cam  20 B. The function of the spring  24  is firstly to push the rotary cam  20 A towards the front and secondly to form a return element tending to push the part  19  towards the rear. 
     The operation of the writing instrument  10  is described below with reference to  FIGS. 3A to 6C . 
     In the state shown in  FIG. 3A , no writing element is selected. The cam  18 A of the cam device  18  co-operates with both cam followers  14 A 1  and  14 B 1 . The cam followers  14 A 1  and  14 B 1  are thus remote from the shoulders  12 A 211 A of their respective guides  12 A 21 . It should be observed that in this position it is not possible to actuate the retraction device  20  since the axial stroke of the cam  18 A, and thus of the plunger cam  20 B, is limited by an abutment  12 A 24  of the front portion  12 A, and more particularly of the second portion  12 A 2  of the body  12 . 
     When it is desired to select a writing element, the front portion  12 A is turned relative to the rear portion  12 B of the body  12  (or vice versa) about the axial direction X, in one direction or the other. In  FIG. 3A , the rear portion  12 B is turned relative to the front portion  12 A along arrow F 3 A 1  so as to select the writing element  14 A, and the cam  18 A co-operates only with the cam follower  14 A 1 . This causes the writing element  14 A to move forwards along arrow F 3 A 2  and the writing element  14 B rearwards along arrow F 3 A 3 .  FIG. 3B  shows the final state after turning as shown in  FIG. 3A , with the cam  18 A engaged with the cam follower  14 A 1 . It should be observed that compared with the state shown in  FIG. 3A , the cam follower  14 A 1  is moved forwards by the cam  18 A, while the cam  18 A no longer co-operates with the cam follower  14 B 1  so that the cam follower  14 B 1  is moved rearwards by the spring  14 B 2  that is in abutment against the shoulder  12 A 211 A. 
     It can be understood that in the state of  FIG. 3B , the writing tip  15 A of the writing element  14 A is still retracted within the front portion  12 A of the body  12 , even though it has been moved forwards by the cam  18 A while selecting the writing element  14 A. In other words, the writing tip  15 A is still in a retracted position. The same applies if it is the element  14 B that is selected instead of the element  14 A, with the tip  15 B remaining retracted within the body  12  when the element  14 B is selected by using the selector device  18 . 
     With reference to  FIGS. 4A to 4F , there follows a description of actuating the retraction device  20  (i.e. the ratchet mechanism  20 ) in order to move the writing tip  15 A from the retracted position to the writing position. Naturally, in the description below, reference is made to only one tooth of each type, however the description applies to all of the teeth of the same type. It should be observed that in order to simplify the figures, only the general size of the part  19  is shown, and not its exact outline. Nevertheless, the positions of the cam  18 A and of the teeth of the plunger cam  20 B are naturally shown accurately. 
       FIG. 4A  corresponds to the position shown in  FIG. 3B , in which the rotary cam  20 A and one pair of teeth  20 BA of the plunger cam  20 B are shown. In this position, the front tooth  20 BA 2  of the plunger cam  20 B is engaged in a passage  21 A of the rotary cam  20 A so that the rotary cam  20 A is rotatably coupled with the plunger cam  20 B, which is itself rotatably coupled with the cam  18 A of the selector device  18 . Thus, when selecting a writing element, as described above with reference to  FIGS. 3A and 3B , the various elements of the ratchet mechanism  20  remain in alignment. Furthermore, the spring  24  pushes the rotary cam  20 A axially against the base  12 A 23  via the washer  26 . This ensures that the teeth  12 A 221  (not shown in  FIG. 4A ) of the front portion  12 A do not run the risk of becoming engaged in the passages  21 B of the rotary cam, thereby leaving the rotary cam  20 B free to turn about the axial direction X. In other words, when all of the writing elements are in the retracted position, and regardless of the configuration of the selector device  18 , the rotary cam  20 A is free to turn relative to the front portion  12 A about the axial direction X, but it is prevented from moving in translation relative to the front portion  12 A along the axial direction X. Furthermore, in the event of a large jolt, any movement of the rotary cam  20 A towards the rear is prevented by the teeth  20 A 2 A co-operating axially in abutment against the teeth  12 A 211 , except in the exceptional circumstance of the teeth  12 A 211  being in alignment with the passages  21 B, in which case the spring  24  would cause the rotary cam  20 A to return immediately against the base  12 A 23 . 
     In order to actuate the ratchet mechanism  20 , the button  23  is pressed forwards in the axial direction X, as represented by arrow F 4 A. This moves the plunger cam  20 B axially. Since the plunger cam  20 B is made integrally with the cam  18 A of the selector device  18 , this also moves the cam  18 A axially, and consequently moves the cam follower  14 A 1 . This movement has the effect of disengaging the front tooth  20 BA 2  of the plunger cam  20 B from the passage  21 A of the rotary cam  20 A. The front tooth  20 BA 2  of the plunger cam  20 B is then received in an axial groove  12 A 25  of the front portion  12 A. This groove  12 A 25  has an opening facing towards the rear in order to receive the front tooth  20 BA 2 . The side walls of the opening converge from the rear towards the front so as to guide the front tooth  20 BA 2  into the groove  12 A 25  and so as to guide it in the circumferential direction C. This also makes it possible to realign the plunger cam  20 B with the rotary cam  20 A, and also the cam  18 A of the selector device with the cam follower of the selected writing element in the event of untimely loss of alignment between them, e.g. as a result of rough handling or when the selector device  18  has been turned insufficiently to select a writing element. Naturally, the plunger cam  20 B is configured so that the front teeth  20 BA 2  are in alignment with the grooves  12 A 25  when a writing element is selected by the selector device  18 . 
     In  FIG. 4B , the rear tooth  20 BA 1  of the plunger cam  20 B is approaching the long tooth  20 A 1 A 1  of the rotary cam  20 A. By continuing to press on the button  23  along arrow F 4 B 1 , the rear tooth  20 BA 1  of the plunger cam  20 B is brought into co-operation with the sloping face of the long tooth  20 A 1 A 1  of the rotary cam  20 A, thereby having the effect of turning the rotary cam  20 A as shown by arrow F 4 B 2  about the axial direction until the rear tooth  20 BA 1  comes into abutment in the circumferential direction against the face of the adjacent short tooth  20 A 1 A 2  that extends in the axial direction X. This position is shown in  FIG. 4C . The button  23 , and thus the cam  18 A and the plunger cam  20 B are at the end of their forward axial stroke. The user then releases axial pressure being exerted on the button  23 , which returns rearwards as a result of the spring  14 A 2  of the writing element  14 A relaxing and as a result of the spring  24  relaxing, as shown by arrow F 4 C, in order to reach the position shown in  FIG. 4D . 
     In  FIG. 4D , the front tooth  20 BA 2  of the plunger cam  20 B co-operates in abutment in the axial direction with the tooth  20 A 1 B 1  of the rotary cam  20 A (since it has pivoted about the axial direction from the position shown in  FIGS. 4A and 4B ), thereby having the effect of coupling the rotary cam  20 A in axial translation towards the rear with the plunger cam  20 B. The spring  14 A 2  of the writing element  14 A continues to act via the cam  18 A to push the plunger cam  20 B rearwards, as shown by arrow F 4 D, so as to reach the position shown in  FIG. 4E . 
     In  FIG. 4E , the second series of teeth  20 A 2  of the rotary cam and one tooth  12 A 221  of the front portion are shown in dashed lines, whereas they are omitted from  FIGS. 4A to 4D  in order to simplify the views. 
     Since the rotary cam  20 A is coupled in axial translation towards the rear with the plunger cam  20 B, it is moved together with the plunger cam  20 B towards the rear under the effect of the spring  14 A 2  of the writing element along arrow F 4 E 1 . The rotary cam  20 A is thus spaced apart rearwards along the axial direction from the base  12 A 23  of the front portion  12 A, while remaining engaged on the rod  12 A 22 , such that the tooth  20 A 2 A co-operates axially with the tooth  12 A 221  of the front portion  12 A. In particular, the tooth  12 A 221  of the front portion  12 A co-operates with the sloping face of the tooth  20 A 2 A of the rotary cam  20 A, thereby having the effect of turning the rotary cam  20 A as shown by arrow F 4 E 2 , so as to bring the tooth  12 A 221  into alignment with the passage  21 B. Once the tooth  12 A 221  and the passage  21 B are in alignment, the spring  14 A 2  continues to push the rotary cam  20 A rearwards so that the tooth  12 A 221  (i.e. in this example the rib  12 A 221 ) becomes engaged in the passage  21 B (i.e. in this example the groove  21 B). Thereafter, the spring  14 A 2  continues to push rearwards as shown by arrow F 4 E 1  in order to reach the position shown in  FIG. 4F . 
     In  FIG. 4F , rearward movement of the rotary cam  20 A and of the plunger cam  20 B is prevented by an axial abutment  12 B 2  (see  FIG. 2 , not shown in  FIGS. 4E and 4F ) that is provided in the rear portion  12 B and that co-operates in abutment with the rotary cam  20 A via the washer  26 . Actuation of the ratchet mechanism  20  has thus terminated and the writing tip  15 A of the writing element  14 A is in the writing position. In this configuration where the writing element is in the writing position, the rotary cam  20 A is rotatably coupled with the front portion  12 A by means of the teeth  12 A 221  engaged in the passages  21 B. Since the rotary cam  20 A is spaced apart from the base  12 A 23  and since the teeth  12 A 221  are free to move axially in the passages  21 B, the rotary cam  20 A is free to move in translation along the axial direction X relative to the front portion  12 A. 
     In this example, since the writing element  14 A is a mechanical pencil, the lead  15 A may either project from the head  14 A 3 , as shown in  FIG. 4F , or else it may be retracted inside the head  14 A 3 . In order to cause the lead  15 A to project from the head  14 A 3 , or more generally in order to propel the lead  15 A from the head  14 A 3 , it suffices to actuate the button  23  over an axial stroke D that is less than the stroke D 1  needed for actuating the ratchet mechanism  20  again. This has the effect of bringing the head  14 A 3  to bear against a shoulder  12 Al 2  inside the front portion  12 A, thereby actuating the lead-propelling mechanism  14 A 4  and propelling the lead  15 A. The ratchet mechanism  20  thus allows the lead to be propelled without itself being fully actuated. Naturally, if the writing tip of the writing element is a stationary tip, such as the ballpoint  15 B, this action has no effect. 
     With reference to  FIGS. 5A to 5E , there follows a description of causing a writing element to pass from the writing position to the retracted position by using the retraction device  20  (i.e. in this example the ratchet mechanism  20 ). 
     The position of  FIG. 5A  corresponds to the position of  FIG. 4F . Pressing forwards in the axial direction X on the button  23  has the effect of actuating the ratchet mechanism  20 , as shown by arrow FSA. 
     Under the action of the button  23 , the rear tooth  20 BA 1  of the plunger cam  20 B co-operates axially with the short tooth  20 A 1 A 2  of the rotary cam  20 A, and more particularly with the sloping face of the short tooth  20 A 1 A 2 . Since the rotary cam  20 A is prevented from turning by the tooth  12 A 221 , but free to move forwards in translation along the axial direction X, the plunger cam  20 B pushes the rotary cam  20 A forwards until the tooth  12 A 221  is disengaged from the passage  21 B. This position is shown in  FIG. 5B . The button  23  moving along the arrow F 5 A drives the spring  24 , the washer  26 , and the rotary cam  20 A, with the rotary cam  20 A remaining continuously pressed, via the washer  26 , against the tooth  20 BA 2  under the action of the spring  24 . Since the rotary cam  20 A is prevented from turning by the tooth  12 A 221 , but free to move forwards in the axial direction X, this set of parts moves axially together until the tooth  12 A 221  is disengaged from the passage  21 B and the rotary cam  20 A comes into abutment against the studs  12 A 23 A. If pressure continues to be applied on the button  23 , the rotary cam  20 A disengages from the tooth  20 BA 2 , while the rear tooth  20 BA 1  of the plunger cam  20 B co-operates axially with the short tooth  20 A 1 A 2  of the rotary cam  20 A, and more particularly with the sloping face of the short tooth  20 A 1 A 2 . 
     When the tooth  12 A 221  is disengaged from the passage  21 B and pressure continues to be applied to the button  23  along arrow F 5 B 1 , the rotary cam  20 A turns about the axial direction under the effect of pressure from the rear tooth  20 BA 1  of the plunger cam  20 B against the sloping face of the short tooth  20 Al 2 A of the rotary cam (see arrow F 5 B 2 ). This effect is accentuated when the rotary cam  20 A is prevented from moving in translation by co-operating axially in abutment against the base  12 A 23 , as shown in  FIG. 5B . The rotary cam  20 B then turns until the rear tooth  20 BA 1  of the plunger cam  20 B co-operates in the circumferential direction in abutment against the axially extending face of the adjacent long tooth  20 A 1 A 1  and is in alignment with the adjacent passage  21 A. This turning also serves to take the tooth  12 A 221  of the front portion  12 A out of alignment with the passage  21 B, thereby causing the rotary cam  20 A to be prevented from moving in translation along the axial direction X between the base  12 A 23  and the tooth  12 A 221 , which now faces the shoulder formed by the tooth  20 A 21 . This position is shown in  FIG. 5C . 
     When the pressure applied to the button  23  is released, the button returns rearwards (see arrow F 5 C) under the effect of the spring  14 A 2  of the writing element and of the spring  24  (given that the rotary cam  20 A is prevented from moving in translation), whereby the front tooth  20 BA 2  of the plunger cam  20 B co-operates axially with the sloping face of the tooth  20 A 1 B 1  of the rotary cam  20 A, thereby turning the rotary cam  20 A. This configuration is shown in  FIG. 5D . 
     The rotary cam  20 A turns under the effect of the tooth  20 BA 2  (see arrow F 5 D 2 ) until the tooth  20 BA 2  co-operates in abutment in the circumferential direction with the axially extending face of the adjacent tooth  20 A 1 B 1  and is in alignment with the passage  21 A. The plunger cam  20 B can then move axially rearwards (see arrow F 5 D 1 ) under the effect of the spring  14 A 2  of the writing element and of the spring  24  until the button  23  comes into abutment against the inside of the rear portion  12 B of the body  12 . The tooth  20 BA 2  of the plunger cam  20 B remains engaged in the passage  21 A of the rotary cam  20 A, whereby the plunger cam  20 B is rotatably coupled about the axial direction X with the rotary cam  20 A. This configuration is shown in  FIG. 5E  and corresponds to the configuration of  FIG. 4A . Actuation of the ratchet mechanism  20  has terminated and the writing element  14 A is in the retracted position. 
     With reference to  FIGS. 6A to 6C , there follows a description of passing a writing element from the writing position to the retracted position by using the return device  22 . 
     The position of  FIG. 6A  corresponds to the position of  FIG. 4F . The rear portion  12 B is turned as shown by arrow F 6 A relative to the front portion  12 A of the body  12  in order to actuate the selector device  18 . 
     While turning, the rear portion  12 B entrains both the cam  18 A of the selector device  18  and also the plunger cam  20 B of the retraction device  20 . Since the rotary cam  20 A is engaged with the tooth  12 A 221 , it is rotatably coupled with the front portion  12 A, and it is therefore not itself turned. During the turning movement of the rear portion  12 B relative to the front portion  12 A, the plunger cam  20 B thus turns in the same manner relative to the rotary cam  20 A. This has the effect of changing the position of the front tooth  20 BA 2  of the plunger cam  20 B relative to the tooth  20 A 1 B 21  of the rotary cam  20 A against which it presses. The front tooth  20 BA 2  thus slides from the face perpendicular to the axial direction X towards the face that slopes relative to the axial direction X of the tooth  20 A 1 B 1  with which it is co-operating. The spring  24  pushes the rotary cam  20 A forwards relative to the plunger cam  20 B, whereby the front tooth  20 BA 2  and the tooth  20 A 1 B 1  do indeed remain in contact with each other, while the rotary cam  20 A becomes progressively disengaged from the tooth  12 A 221  of the front portion  12 A. Furthermore, the cam  18 A of the selector device  18  also turns relative to the writing elements, such that it begins to disengage from the element  14 A, which begins to move rearwards under the effect of the spring  14 A 2 . This configuration is shown in  FIG. 6B . 
     By continuing the turning movement as shown by arrow F 6 B 1 , the front tooth  20 BA 2  of the plunger cam  20 B continues its stroke along the sloping face of the tooth  20 A 1 B 1  of the rotary cam  20 A until it engages in the adjacent passage  21 A, while the spring  24  continues to push the rotary cam  20 A forwards until it is totally disengaged from the tooth  12 A 221 . It will naturally be understood that the axial movement of the rotary cam  20 A relative to the plunger cam  20 B and the front portion  12 A follows the axial stroke of the front tooth  20 BA 2  on the sloping face of the tooth  20 A 1 B 1 . The rotary cam  20 A moves forwards until it comes into abutment against the base  12 A 23 . When the rotary cam  20 A is disengaged from the tooth  12 A 221 , it is no longer rotatably coupled with the front portion  12 A, while the engagement of the front tooth  20 BA 2  in the passage  21 A couples the rotary cam  20 A to turn with the plunger cam  20 B. The rotary cam  20 A and the plunger cam  20 B turning together serves to bring the tooth  12 A 221  of the front portion  12 A out of alignment with the passage  21 B, such that the tooth  12 A 221  co-operates axially with the tooth  20 A 2 A and prevents the rotary cam  20 A from moving axially in translation towards the rear. Under the effect of the spring  14 A 2 , the plunger cam  20 B moves rearwards relative to the rotary cam  20 A along arrow F 6 B 2 , thereby bringing the writing element  14 A into the retracted position. This configuration is shown in  FIG. 6C . Thus by actuating the selector device  18  while a writing element is selected, the return device  22 , which in this example comprises the teeth  12 A 221  and the passages  21 B, serves to cause the rotary cam  20 A to turn relative to the plunger cam  20 B so as to release the plunger cam  20 B relative to the rotary cam  20 A in the axial direction X, and brings the writing element into the retracted position. It should be observed in this example that it is also possible to bring the writing element into the retracted position by actuating the return device  22  so that it turns in the direction opposite to the arrows F 6 A and F 6 B 1 . 
     Although the present disclosure is described with reference to specific embodiments, it is clear that modifications and changes may be carried out on those examples without going beyond the general ambit of the invention as defined by the claims. In particular, individual characteristics of the various embodiments shown and/or mentioned may be combined in additional embodiments. Consequently, the description and the drawings should be considered in a sense that is illustrative rather than restrictive.