Patent Publication Number: US-11380496-B2

Title: Key module

Description:
TECHNICAL FIELD 
     The present invention relates to a key module according to the main claims. The key module may be used in a computer keyboard, for example. 
     BACKGROUND 
     Most available key modules (which may also referred to as key module) are relatively high and hard to integrate into the flat keyboards or notebooks. In usual modules, also a “clicking” is variant is realized on the basis of the two-part tappet, in order to output an indication of an actuated key to a user of the key module. In flat key modules, the clicking sound is realized by means of an additional mechanism due to the lack of available space. Consequently, electric switching process is decoupled from the process of producing the clicking sound and thus does not take place synchronously with the production of the clicking sound. Also, LED illumination is designed from one side in most known key modules so that uniform illumination of a surface facing the user of the key module is not possible with one LED (in particular keys with two or three symbols). Furthermore, most key modules are designed to be relatively untight for cost reasons so that damage to the keyboards quickly occurs when water or watery liquids are spilt, for example. The weak spots in the key module with respect to damage caused by liquids especially are the electric switching mechanism and guidance of the tappet. Moreover, on the part of the user, there is often a need for different key modules, for example with a linear force path upon actuation, with a pressure point for actuation, with a clicking sound upon actuation and with various force-displacement characteristics. However, such variety necessitates an enormous variety of variants of key modules, which mostly are to be produced in different modes of production and thus at high cost, to be kept available by the key manufacturers. Also, the guidance of the tappet in low modules upon actuation of such a key module is shortened, which increases the likelihood of canting of the key. In a so-called “silent” design of a key module, an expensive two-component tappet is used, which significantly increases the overall module cost. Also, reduced constructional height makes electronic devices (especially when using SMD-based components) hard or impossible to mount the upper side of a circuit board, in particular in connection with frame assembly. Moreover, assembly on the bottom side of the key modules also is problematic because certain components should be directly attached to the modules. Significant difficulties result therefrom in a subsequent module soldering process (especially when using a solder wave), because all components need to be covered. In addition, there is the risk of destruction of the electronic devices due to electrostatic discharge (of up to 8 KV). 
     Against this background, the present invention provides an improved key module according to the main claims. Preferred embodiments are obvious from the dependent claims and the subsequent description. 
     SUMMARY OF THE INVENTION 
     The approach presented here provides a key module comprising:
         an actuation element comprising a cam nose, wherein the actuation element is supported to be movable along a movement axis in a housing element;   a contactor unit with a contact nose movable in the direction of the movement axis and transverse to the direction of the movement axis;   a contact element formed and arranged for establishing electric contact with the contact nose; and   the housing element for accommodating the contact element, the contactor unit and the actuation element,   wherein the actuation element and/or the cam nose comprises at least one constructive element formed to deflect the contact nose from a rest position adjacent to the contact element in the direction along and/or transverse to the movement axis upon a defined movement of the actuation element, then abruptly release it so that the movable contact nose returns to the rest position and strikes the contact element and/or the housing element, wherein electric contact with the contact element is established and acoustic noise is produced.       

     An actuation element may be seen as a tappet, for example. The cam nose may be seen as a protrusion of the actuation element, for example, which engages behind another element such as the contact nose, deflects it and/or takes it along in the case of movement in the direction of the movement axis. A movement axis may be an axis along which the actuation element is moved or movable with respect to the housing element. A contact element may be seen as an element at least partially consisting of electrically conductive material and fixed at a predetermined position in the housing element, for example. The housing element may, for example, be seen as a bottom element for accommodating the contactor unit, the contact element and the actuation element, wherein the housing element may further also comprise, as a further portion, a cover element to encapsulate the components mentioned. A contactor unit may be seen as element comprising a contact nose movable in various directions, wherein the contact nose may be seen as a region of the contactor unit in which electric contact to a corresponding counterpart may be closed. The contact element may, for example, serve as a counterpart to the contactor unit, in order to close an electric contact in the form of a switch. A constructive element may be seen as a guiding surface, a strut, a contour of the cam nose (particularly on its outer surface) or surface on the cam nose, for example, formed to deflect the contact nose in a direction along and/or transverse to the actuation axis, when the contact nose is guided, for example taken along by the cam nose and deflected on the constructive element when the actuation element is moving along the actuation axis. 
     For example, the housing element may comprise a cover element as a subsection through which the actuation element is guided and/or supported. Also, the housing element may be formed to accommodate the contact element, the contactor unit and at least part of the actuation element. The actuation element and/or the cam nose may comprise a constructive element or a guiding surface oriented obliquely with respect to the direction of the movement axis and formed to deflect the contact nose from a rest position adjacent to the contact piece in the direction along and/or transverse to the movement axis, when the contact nose is taken along or deflected by the cam nose when the actuation element is being depressed. 
     The approach presented here is based on the finding that, by using the cam nose on the actuation element in a movement of the actuation element along the movement axis, i.e. when depressing the actuation element, the contact nose, as the region of the contactor unit designed so as to be the most movable one, is taken along or around and guided along the constructive element until the contact nose is laterally deflected by sliding on the constructive element so far that it slides laterally past the cam nose and hereby is released (for example abruptly) so as to snap back into its original position, i.e. the rest position. Hereby, on the one hand a clicking noise can be generated, which is very close in time to electrically contacting the contact nose with the contact element, so that the clicking sound may also be perceived as very promptly as confirmation of the electric contact between two electric contacts by a user of the key module. The approach presented here offers the advantage that constructive effort of equipping the key module with a unit for producing the clicking sound can be avoided by deflecting and snapping back of the contact nose of the contactor unit as a part of an electric contact switch. In this way, a key module which is inexpensive and simple to manufacture, yet still has the advantages mostly highly valued by users can be provided. 
     According to a special embodiment of the approach presented here, the constructive element may be formed to guide the contact nose around the cam nose when the actuation element is being depressed. Such guiding around may mean that the contact nose has the greatest distance to the movement axis at the time of this guiding around, for example. In this manner, the contact nose may be released very easily and at a defined distance, in order to both produce the clicking sound after snapping back and ensure the electric connection in a reversibly repeatable way after depressing the actuation element by a certain distance. 
     What is also advantageous is an embodiment of the approach presented here wherein the housing element comprises a distance limitation element to limit a distance of movement of the contact nose in the direction of the movement axis. Such an embodiment of the approach presented here offers the advantage that by providing the distance limitation element a distance of movement of the contact nose may be limited so that excessive strain on the contact nose, which would result in a clicking noise perceived as too loud by a user of the key module, can be avoided. 
     What is also advantageous is an embodiment of the approach presented here wherein cam nose and/or the constructive element comprises a guiding surface oblique with respect to the orientation of the movement axis, in particular wherein the guiding surface is arranged so as to proceed in the direction of a movement of the cam nose from an original position. Alternatively or additionally, the contactor unit may also be formed to hit the contact nose on the at least one portion of the housing element after a deflection on the constructive element. Such an embodiment offers the advantage of both forming a defined surface for deflecting the contact nose with as little force and friction as possible and providing a strike surface on the housing element or cover element, which may be both reinforced correspondingly and structured correspondingly for producing a certain sound and connected to further regions of the housing element and/or cover element. 
     What is also advantageous is an embodiment of the approach presented here in which the contactor unit at least partially comprises a U-shaped portion, in particular wherein the contact nose is arranged on one end of the U-shaped portion of the contactor unit, and/or wherein a U-shape of the contactor unit is formed in a plane oriented substantially perpendicularly with respect to the movement axis. Such an embodiment of the approach proposed here offers the advantage of a contactor unit being very easy to realize technically, yet having the contact nose with corresponding desired mobility various directions of. For example, the contactor unit may be formed as a correspondingly shaped bent metal strip. 
     What is also conceivable is an embodiment of the approach presented here in which the contactor unit has (mechanical) stiffness greater with respect to movement of the contact nose in the direction of the movement axis then in the direction transverse to the movement axis. Such an embodiment of the approach proposed here offers the advantage that the contact nose moves significantly more quickly in the direction of the movement axis than transverse to the movement axis when moving back after being guided around over the cam nose. In this way, it is ensured that the clicking sound is caused substantially by movement in the direction of the movement axis, which is designed clearly reproducibly and offers sufficient snapping path for the contact nose so as to generate the clicking sound in a clearly perceptible manner for the user. 
     What is particularly reliable and long-life is an embodiment of the approach proposed here in which the contactor unit comprises, in the region of the contact nose, a strike portion formed to strike the contact nose on the at least one portion of the housing element or the cover element. In particular, the strike portion may comprise a surface aligned substantially in parallel with the at least one portion of the housing element or the cover element or part of the cover element, and/or wherein the strike portion is formed by an angled part of the contactor unit or the contact nose, and/or wherein the strike portion has a length of a surface oriented toward the at least one portion of the housing element or the cover element greater than a thickness. 
     So as to ensure quick and repeated actuation of the key module, the return movement of the actuation element along the movement axis should take place as unhindered as possible or only with little hindrance. What is particularly advantageously is an embodiment of the approach proposed here in which the cam nose of the actuation element comprises at least one reset surface portion, which comprises a surface oriented obliquely with respect to the direction of the movement axis, in particular wherein the reset surface portion is formed to guide the contact nose around the cam nose upon a reset of the actuation element. In this way, it can be ensured that the contact nose or the contact tip can be guided around the cam nose easily and without increased effort when the actuation element moves back to the rest position. In addition, there is the possibility of producing a clicking sound also in the reset of the actuation element, in this case for example when the contact nose is lifted from the contact element and is guided back onto the contact element after being guided around the cam nose. 
     According to another embodiment of the approach proposed here, the contactor unit may have, in the region of the contact nose, a surface portion the surface of which is oriented obliquely with respect to the direction of the movement axis, in particular the surface of which at most is oriented at an acute angle with respect to the constructive element, in particular the surface of which is aligned in parallel with the constructive element. This surface portion may be formed and arranged to slide along on the constructive element. Such an embodiment of the approach presented here offers the advantage of particularly low-friction sliding of the surface portion on the constructive element. In this way, it is achieved that the key module can be actuated with as little force as possible and reliably. 
     What is particularly advantageous is an embodiment of the approach proposed here in which the at least one portion of the housing element or the cover element has a cover slope with a surface oblique with respect to the direction of the movement axis in the region of an opening through which the actuation element is guided, and/or wherein the actuation element has a tappet slope with a surface oblique with respect to the direction of the movement axis in a passage area surrounded by the at least one portion of the housing element or the cover element. In particular, the cover slope may be arranged circumferentially around the opening in the at least one portion of the housing element or in the cover element. Alternatively or additionally, the tappet slope may also be arranged circumferentially around the actuation element in the passage area. Such an embodiment offers the advantage of a particularly tight lock between at least one portion of the housing element or the cover element and the actuation element, in particular for avoiding entry of the liquids into the key module. 
     What is particularly well protected against entry of liquids is a key module according to an embodiment of the approach presented here in which a sealing element arranged between the at least one portion of the housing element or the cover element and the housing or bottom element is provided, in particular wherein the sealing element is arranged or press-fit in a groove of the at least one portion of the housing element or the cover element and/or a groove of the housing or bottom element. In such an embodiment, in particular, capillary action can be utilized to prevent the liquid from entering the key module. 
     In an embodiment of the approach proposed here which offers particularly great protection against liquids entering the key module, the sealing element may close the region of the actuation element, of the contactor unit and of the contact element in a fluid-tight manner, in particular wherein the sealing element is formed in the shape of a labyrinth seal or as a labyrinth seal. Hereby, a hermetic seal of the components most important for the function of the key module can be achieved with little cost of materials. 
     According to another embodiment of the approach proposed here, the at least one portion of the housing element or the cover element may comprise at least one light guiding element, in particular wherein the light guiding element is formed at least partially annularly around a region in which the actuation element is guided through the at least one portion of the housing element or the cover element. Such an embodiment offers the advantage of a particularly good possibility of eliminating a keycap to be put on the key module, so that the user can recognize the meaning of the symbols on the keycap quickly, unequivocally and reliably. 
     So as to ensure maximum protection against canting of the actuation element when being depressed, according to a further embodiment, the actuation element may comprise a cylindrical keycap support portion in a passage region, in which it protrudes through the at least one portion of the housing element or the cover element, and at least one rib on a guiding portion on an outer surface adjacent to the keycap support portion, and wherein the housing or bottom element comprises, for accommodating the guiding portion of the actuation element, at least one accommodating bowl with at least one recess for accommodating the rib of the actuation element. 
     The actuation element can be guided in a particularly safe manner when being depressed if the actuation element comprises an at least partially hollow cylindrical portion in the region of the guiding portion, in particular wherein the at least one rib is formed on an outer surface of the hollow cylindrical portion, and/or wherein a guiding piston of the housing element engages the hollow cylindrical portion of the guiding portion of the actuation element. 
     A key module according to a further embodiment can be made particularly low-noise by providing a shock absorber element arranged between the actuation element and the housing element, in particular wherein the shock absorber element is formed to be cylindrical or annular. Such an embodiment of the approach proposed here offers the advantage of using standardized conventional components, such as rubber stoppers, whereby an inexpensive variant of the low-noise key module can be produced. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The invention shall be explained in greater detail by way of example on the basis of the attached drawings, in which: 
         FIG. 1  shows an exploded view of a key module according to an embodiment of the present invention; 
         FIG. 2  shows a cross-sectional illustration of a module variant of a key module  100  with linear force-displacement characteristic; and 
         FIG. 3  shows a cross-sectional illustration of a further embodiment of the present invention as a key module; 
         FIG. 4  shows a cross-sectional illustration of a further embodiment of the present invention as a key module; 
         FIG. 5  shows a cross-sectional illustration of a key module according to an embodiment of the approach presented here; 
         FIG. 6  shows a cross-sectional illustration of the embodiment of the present invention illustrated in  FIG. 5  as a key module; 
         FIG. 7  shows a cross-sectional illustration of the embodiment of the present invention illustrated in  FIG. 6  as a key module; 
         FIG. 8  shows a cross-sectional illustration of the embodiment of the present invention illustrated in  FIG. 7  as a key module; 
         FIG. 9  shows a top view of an embodiment of the present invention as a key module; 
         FIG. 10  shows a side view of an embodiment of the present invention as a key module in assembled form; 
         FIG. 11  shows a sectional view through the key module corresponding to the section A-A from the illustration according to  FIG. 10 ; 
         FIG. 12  shows a sectional view through the key module corresponding to the section A-A from the illustration according to  FIG. 10 ; 
         FIG. 13  shows a perspective view of the cover element with the light guiding element integrated therein; 
         FIG. 14  shows a perspective illustration of the tappet for use in an embodiment of the present invention; 
         FIG. 15  shows a perspective illustration of a housing element; 
         FIG. 16  shows a side view of a key module installed on a circuit board; 
         FIG. 17  shows a side view of a further key module also installed on a circuit board; and 
         FIG. 18  shows a perspective view on a key module on the housing element. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     In the subsequent description of preferred embodiments of the present invention, the same or similar reference numerals shall be used for similarly acting elements illustrated in the various figures, wherein repeated description of these elements shall be omitted. 
       FIG. 1  shows an exploded view of a key module  100  according to an embodiment of the present invention. The key module  100  may be constructed as a modular construction set and substantially includes tappet  105 , cover element  110 , contactor unit  115 , contact element  120 , compression spring  125  and housing unit  130  (which may synonymously also be referred to as a housing element, bottom element or bottom unit, wherein in the subsequent description the bottom part of the accommodating body of the components of the key module  100  is meant by housing element or housing unit, without limitation of generality, but also cover element  110  may be seen as a part or portion of the housing element) as components. The tappet  105  (which may synonymously also be referred to as an actuation element) includes a cam nose  135 , which can take along a contact nose  140  of the contactor unit  115  and deflect the same from a rest position, as will be explained in greater detail in the subsequent description. In the present case, the contactor unit  115  is formed as a U-shaped metal element and thus is electrically conductive. The contact nose  140  is arranged in one end of the contactor unit  115  and includes further components described in greater detail in the following apart from a contact tip  145 , via which an electric contact between the contactor unit  115  and the contact element  120  can be closed. Furthermore, it can be seen that the key module  100  illustrated in  FIG. 1  includes a sealing element  150 , which is set on the housing unit  130  and thus enables fluid-tight closure or inclusion of the contactor unit  115 , the bottom part of the tappet  105 , in particular the cam nose  135 , so as to hereby protect or ensure the operability of the key module  100  as well as possible against liquids acting from the outside. For example, the sealing element  150  may be formed circumferentially and/or have a triangular cross-sectional profile, in order to engage a groove in the cover element  110 . illustrated in  FIG. 1  and hereby cause optimum seal effect. In the embodiment illustrated in  FIG. 1 , the compression spring  115  is a helical coil spring, for example of metal; but it is also conceivable to use an alternative spring element, such as a plastics spring or a fluid-filled pad, in order to return the tappet  115  into its original position again after depressing. 
     The key module  100  may be realized inexpensively in three variants in terms of function. Substantially, what changes is especially the actuation nose on the tappet  105 , which is also referred to as cam nose  135  here, and in part a contour wall as constructive element  140  in the housing element  130 , subsequently also referred to as guiding wall. 
     The tappet to  105  further comprises a cylindrical keycap supporting portion  160  (onto which a symbol-bearing keycap not illustrated in  FIG. 1  is clipped) in a passage area in which it projects through the cover element  110 . Moreover, the tappet  105  comprises at least one rib  170  on a guiding portion  165  adjacent to the keycap supporting portion  160  on an outside  167 . For example, a wall thickness of the wing or wings  170  may be at most half, advantageously at most one third, of a diameter of the cylindrical keycap supporting portion  160 . 
     In the assembled state of the key module  100 , the guiding portion  165  is accommodated in an accommodating bowl  175  of the housing element  130 , wherein the accommodating bowl comprises recesses not illustrated in  FIG. 1  for accommodating one wing  170  of the guiding portion  165  of the tappet  105  each, as will be explained in greater detail in the following. The guiding portion  165  may also be formed as a hollow-cylindrical portion  180  on the outsides  67  of which the wing or wings  170  are arranged. In the assembled state of the key module  100 , for example, a guiding piston in the accommodating ball  175  engages this hollow-cylindrical portion  180  so that the guiding portion  165  can be guided very robustly when the tappet  105  is being moved or depressed. 
     By using the tappet  105  with the keycap supporting portion  160 , which projects through an advantageously circular opening of the cover element  110 , the tappet  105  can be guided with as little canting as possible when the tappet  105  is being depressed. This low-canting guidance of the tappet  105  when being depressed can be enhanced further if the wing (or wings)  170  of the guiding portion  165  of the tappet  105  engage the recess(es) of the accommodating ball  175 , and thus can ensure both guidance of the tappet  105  the direction of the movement during depressing and guidance with respect to rotation. Hereby, very low-canting actuation of the tappet  105  of the key module  100  can be ensured. 
       FIG. 2  shows a cross-sectional illustration of a module variant of a key module  100  with a linear force-displacement characteristic. The force-displacement characteristic can be realized arbitrarily by adapting or selecting a suitable compression spring  125 . From  FIG. 2 , it can also be seen that the tappet  105  can be moved with respect to the housing element  130  in the direction of a movement access  200 . For example, this movement may be effected by depressing the tappet  105 , wherein the tappet is again returned to its original position or rest position illustrated in  FIG. 2  after a keystroke on the tappet  105  by the reset force of the compression spring  125 . 
     Moreover, it can be seen in  FIG. 2  that the tappet  105  has a tappet slope  220 , which includes a surface oriented obliquely with respect to the axis CC, in a passage area  210 , in which it is guided through opening  215  of the cover element  110 . In addition, also the cover element  110  comprises, in the region of the opening  215 , a cover slope  225 , which includes a surface oriented obliquely with respect to the movement access  200 . Especially, the surface of the tappet slope  220  the surface of the cover slope  225  may substantially be aligned in parallel and have a seal effect in the rest position of the key module  100  illustrated in  FIG. 2 , in order to prevent liquids from entering an inside of the key module  100  as effectively as possible. Furthermore, the key module  100  comprises a shock absorber element  230 , which is set on or in a guiding piston  235  of the housing element  130 , for example, and which absorbs an impact of the tappet  105  onto this part of the housing element  130 . In this way, a reduced-noise variant of the key module  100  can be produced. It is particularly advantageous if a rubber stopper cut from a round ready-made product and inserted in the guiding piston  230  is used as the shock absorber element  230 , for example, because such an embodiment can be produced very inexpensively. 
       FIG. 3  shows a cross-sectional illustration of a further embodiment of the present invention as a key module  100 , wherein a solution for implementing a pressure point is used in this embodiment. Here, the user of the key module  100  may sense in a tactile manner the crossing of a certain distance of the tappet during the depression. For example, this tactile sensing may be realized by the cam nose  135  comprising a protrusion in the direction of the contact nose  140 , and thus the user having to exert increased depressing pressure when depressing the tappet, when the contact nose  140  is to slide around the cam nose  135 . The user of the key module  100  feels the increased depressing pressure and thereby recognizes a certain distance by which the tappet  105  has already been depressed. 
       FIG. 4  shows a cross-sectional illustration of a further embodiment of the present invention as a key module  100 , wherein a solution for implementing a pressure and clicking point is used. Hereby, the advantages previously mentioned are achieved in a very efficient way. The actuation of the key module  100  shall be explained in greater detail in the following with reference to the embodiment illustrated in  FIG. 4 , with it being obvious that the embodiments illustrated in  FIGS. 2 to 3  can be used corresponding to the subsequent description. 
     Particular focus lies on the click variant described with reference to the subsequent figures is an embodiment of a key module  100 . In contrast to most solutions known worldwide, in which a clicking sound is produced with an additional part or additional mechanism supplementary to the electric switching mechanism, the clicking sound is induced directly by one of the electric switch contacts, for example by an impact of part of the contactor unit  115 , especially the contact nose  140 , on the cover element  110  or tappet  105  after passing the cam nose  135 , according to the approach presented here. Thus, only the components of the electric switch contacts are necessary as part or component for providing the click and switch function. 
     According to the embodiments of the approach presented here, the contactor unit  115  is designed so that at least part of the contactor unit  115  can be deflected (actuated) three-dimensionally, like the contact nose  140 . The contactor unit  115  is installed in the switch module or key module  100  in a preloaded state so that, for example, gold crosspoint contacts of the contactor unit  115  (forming the contact tip  145 , for example) and of the fixed contact or the contact element  120  are pressed onto each other. With a defined preload, a defined contact force is set in the switched (i.e. electrically connected) state, which remains virtually unchanged over the entire life. This preload or actuation movement takes place in the horizontal plane, i.e. in a direction transverse or perpendicular to the movement axis CC. In particular, this is valid for the linear and pressure point variants of the key module  100  mentioned here. 
     In the clicker variant according to the embodiment presented here, in which also a clicking sound is produced in addition to the electrical switching, the contactor unit  115  or the contact nose  140  as part of the contactor unit  115  is deflected also in the actuation direction or in the direction of the movement axis  200 , which means vertically corresponding to the illustration in  FIG. 4 , by means of the cam nose  135 . This is effected by the cam nose  135  comprising a constructive element  400 , which comprises a contour with a guiding surface  410  obliquely oriented with respect to the movement axis  200 , for example. Hereby, when the actuation element  105  is being depressed, the contact nose  140  is at first taken along on the constructive element  400  or the guiding surface  410  as long as a force component acting by way of the spring action of the contact element  115  in the direction of the movement axis  200  is smaller than a force component resulting from friction of the contact nose  140  on the guiding surface  410 . Additionally or alternatively, a distance of movement of the contact nose  140  in the direction of the movement axis  200  may be limited by a distance limiting element  430 , which is formed by a part of the housing element  130 , for example. In this way, it is ensured that both defined deflection of the contact nose  140  by a predetermined distance of movement is ensured in a reproducible manner and thus reproducible tension of the contact nose  140  can be used for a reproducible clicking sound with desired volume. 
     When the cam nose  135  is being depressed further, the contact nose  140  is deflected transversely to the direction of the movement axis  200  by the cam nose  135 , i.e. to the right in the horizontal direction in the illustration of  FIG. 4 , wherein the contact nose  140  is preloaded further relative to a rest position. After a defined actuation or movement distance of the actuation element  105 , the contact nose  140  slides around the cam nose  135 , wherein the contact nose  140  slides around a cam nose protrusion  420  and thus is released abruptly so that the cam nose  140  is released both in the direction of the movement axis  200  and transverse to the movement axis  200  (more specifically, as long as the cam nose  135  does not block a path transverse to the movement axis  200 ). Thus, a person actuating the actuation element  105  may be signaled in a tactile manner that the deflection of the contact nose  140  has taken place. 
       FIG. 5  shows a cross-sectional illustration of a key module  100  according to an embodiment of the approach presented here, wherein the contact nose  140  now is limited in further movement in the direction of the movement axis  200  by the distance limiting element  430  and thus is deflected in maximum deflection with reference to the movement axis  200 . This means that the distance of the contact nose  142  the movement axis  200  is maximum in this position. In this position illustrated in  FIG. 5 , the contact nose  140  of the contactor unit  115  is deflected transversely to the direction of movement by the cam nose  135  or the guiding surface  410 . 
     Furthermore, there may be provided a surface portion  500  of the contact nose  140  which is oriented obliquely with respect to the direction of the movement axis  200 . Specifically, the surface of the surface portion  500  may be oriented at most at an acute angle to the movement axis  200 , wherein particularly small sliding resistance can be achieved when the contact nose  140  slides along on a reset surface portion described in greater detail in the following, if the surface of the surface portion  500  is aligned in parallel with this reset surface portion. 
       FIG. 6  shows a cross-sectional illustration of the embodiment of the present invention illustrated in  FIG. 5  as a key module  100 , wherein the contact nose  140  now is deflected at a point of maximum deflection transversely to the movement axis  200  and unlatches when the actuation element  15  is being depressed further. Starting from the point at which the contact nose  140  unlatches, the contactor unit  115  or the contact nose  140  is released again and can return to the original position or rest position both in vertical (which is a longitudinal direction of the movement axis  200 ) and in horizontal direction in  FIG. 5  (which is in a direction transverse to the movement axis  200 ). To this end, the cover element  110  comprises a strike wall  600  on which a strike portion  610  of the contact nose  140  strikes to produce a clicking sound, as will be described in greater detail in the following. 
       FIG. 7  shows a cross-sectional illustration of the embodiment of the present invention illustrated in  FIG. 5  as a key module  100 , wherein the contact nose  140  now strikes on the strike wall  600  of the cover element  110  after unlatching and hereby produces a clicking sound. Because the (mechanical) stiffness of the contactor unit  115  has been designed significantly greater in vertical direction than horizontal direction, however, according to the embodiment presented here, the contact nose  140  of the contactor unit  115  first strikes against the strike wall  600  of the cover element  110  with a surface (referred to as strike portion  610  here) defined therefor and produces a desired defined clicking noise. For example, the strike portion  610  may comprise a surface aligned substantially in parallel to the cover element  110  or the strike wall  600  of the cover element  110 . Also, the strike portion  610  may be formed by an angled part of the contactor unit  110  or the contact nose  140  and additionally or alternatively may have a greater length of a surface oriented toward the cover element  110  than a thickness. 
     After the strike of the contactor unit or the contact nose  140  the cover element  110  or the strike wall  610 , the contactor unit  110  or the contact nose  140  the horizontal plane, i.e. towards the tappet  105  or the contact element  120 , the electric contact is closed with predefined force. 
     What can also be seen in  FIG. 7  is a reset surface portion  700  on a side of the cam nose  135 , which engages the surface portion  500  of the contact nose  140  assisted by the spring  125  in an upward movement of the tappet  105  after the tappet  105  or actuation element  105  is released and again deflects the contact nose  140  to the right, which is transverse to the movement axis  200 , so as to deflect the contact nose  140  to the right, i.e. transverse to the extension direction of the movement axis  200 , by the reset surface portion  700  to bring the tappet  105  again to the original position or initial position or rest position. 
       FIG. 8  shows a cross-sectional illustration of the embodiment of the present invention illustrated in  FIG. 6  as a key module  100 , wherein the contact nose  140  has now again been guided into the rest position after striking on the cover element  110 , and thus electric contact between the contact tip  145  of the contactor element  115  and the contact element  120  is closed. 
       FIG. 8  thus shows a cross-sectional illustration of the embodiment of the present invention illustrated in  FIG. 7  as a key module  100 , wherein the contact nose  140  now has slid past the strike wall  600  after striking on the strike portion  610  and has been returned to the rest position. 
     After releasing the tappet  115 , due to the reset force of the compression spring  125 , the return of the tappet  105  to an original position takes place. In this process, the contactor unit  115  of the contact nose  140  is deflected in the right direction from  FIG. 7 , i.e. horizontally or transversely to the direction of the movement axis  200 , by a reset surface portion  700  of the cam nose  135  formed as a slope of the tappet  105 . Here, the contact nose  140  slides over the actuation nose or cam nose  135 , strikes again, but on the tappet  105 , and produces a second clicking noise, which may be less intensive than the first clicking noise due to design of the geometry of the constructive element  400  (particularly the inclination of the surfaces of the cam nose  135 ), for example. 
     The sound and the intensity of the clicking sound may be adjusted arbitrarily by the deflection path, material properties of the contactor unit  115 , distance to the strike surface  610 , stiffness and weight of the contactor unit or the contact nose  140 . 
     Due to the small constructional height of the embodiment of the key module  100  presented here, it is useful to enhance the anti-canting protection of the actuation guidance for the actuation or the depression of the tappet  105  in the key module  100 . In order to achieve this with limited length of a guiding device for guiding the movement of the tappet along the movement axis  200 , the lower guidance, i.e. a guiding device in the region of the housing element  130 , should be designed to be as narrow as possible (for example about 1 mm) and the upper guidance, i.e. a guiding device in the region of the cover element  110  or the tappet  105 , to be as wide as possible (to a certain degree). This poses a technical challenge because a guiding pin (usual design) with a diameter of 1 mm does not exhibit sufficient strength (for example in the case of providing a design of plastics material) and, if necessary, would have to be manufactured in a very costly manner from special materials. For this reason, the tappet  105  according to the embodiment presented here with designed such that the upper guidance in the region of the tappet  105  takes on a cylindrical shape with great diameter (which is easy to manufacture). 
       FIG. 9  shows a top view of an embodiment of the present invention as a key module  100 , wherein  FIG. 9  represents a top view onto an open housing element  130  without a cover element  110  being clipped on, but with inserted tappet  105 . In addition to the housing element  130 , the contact element  120 , the contactor unit  115  including contact nose  140  and contact tip  145 , the strike portion  610 , the guiding wall  400 , the sealing element  150  and the shock absorber element  230  can be seen. Furthermore, what can be seen is the keycap supporting portion  160  of the tappet in top view, wherein keycap support ribs  900  arranged in a cruciform manner and ensuring secure and rotational-locked mounting of the keycaps (which are not illustrated in  FIG. 9 ) to be clipped or stuck on the tappet  105  can be seen. 
       FIG. 10  shows a side view of an embodiment of the present invention as a key module  100  in the assembled form, i.e. with cover element  110  and housing element  130  clipped together and the further components arranged therein, according to the preceding embodiments. Here, the key module  100  is illustrated in the depressed state, which is the actuated state. What is also illustrated is the layers of a first section A-A and of a second section B-B through the key module  100 , the sectional views of which will be explained in greater detail in the subsequent embodiments. 
       FIG. 11  shows a sectional view through the key module  100  corresponding to the section A-A from the illustration according to  FIG. 10 . Since wings  170  are placed on a stable cylindrical sleeve, the outside  167  of the guiding portion  165  of the tappet  105 , which engage at least one (or several) recesses  1100  of the accommodating ball  175  of the housing element  130 , the overall stiffness of the tappet  105  also is given in usual material designs. Moreover, the protection against rotation of the tappet  105  is realized by the cruciform guidance of the wings  170  engaging the recesses  1100 . The lower guidance thus was designed in the guiding portion  165  in the housing element  130  as recesses  1100  for ribs (which may also be referred to as wings  170 ) of the tappet  105 , which specifically are oriented in a cruciform way and provided with a wing width of about 1 mm, for example. The guidance of the tappet  105  here takes place on the side surfaces of the wings  170  arranged in cruciform way in the recesses  1100  of this guiding portion  165 . Thus, in both main stress directions, the guidance which is are equal to the thickness of the wings  170  arranged in cruciform way, which is about 1 mm, for example. 
       FIG. 12  shows a sectional view through the key module  100  corresponding to the section B-B from the illustration according to  FIG. 10 . What can be seen in addition to the cover element  110  is the tappet  105 , wherein the keycap supporting ribs  900  in form of ribs arranged in a cruciform way and to which a keycap not illustrated in  FIG. 12  can be stuck are also illustrated. What also can be seen is a light guiding element  1210  of the cover element  110 , which is arranged in an at least partially annular way around an opening  215  through which the tappet  105  is guided. This light guiding element  1210  serves to improve the illumination of the keycap. Here, the light guiding element  1210  is designed such that it extends from the cover element  110  (from out of the plane of projection according to the illustration from  FIG. 12 , for example) and is formed of transparent material. In particular, the light guiding element  1210  may project through the cover element  110  on the opposite side of the light source and be designed to be transparent so that, on the back side of the cover element  110  illustrated in  FIG. 12 , the light guide element  1210  also is integrated in an inexpensive manner as an at least partially round, designed to be round around the tappet  105 , in order to be able to emit light as uniformly as possible onto a keycap clipped on the tappet  105 . So as to transport a light to a side opposite the cover element  110 , the preferably at least partially annular light guide was integrated as the light guiding element  1210  in the cover element  110  in an inexpensive way. 
       FIG. 13  shows a perspective view of the cover element  110  with the light guiding element  1210  integrated therein. The uniform emission of the light can be designed in various regions of the cover element  110  by introducing reflecting structures or surfaces with different diffusion values on/in the light guiding element  1210  or different positions of the light guiding element  1210 . 
       FIG. 14  shows a perspective illustration of the tappet  105  with the wings  1100 , the cam nose  135 , the reset surface portion  700  and the tappet slope  220 . 
     A relatively good seal with positive locking of the key module  100 , at least in the non-actuated state, is ensured by the interface between the cover element  110  with the cover slope  225  and the tappet  105  with the tappet slope  220 , which form a conical ring stop. Additionally, in contrast to most known key modules, the upper guidance is formed as a cylindrical holed sleeve, which means a cylindrical guiding portion  160  of the tappet  105 , which may be guided in the opening  215 . This embodiment prevents the entry of foreign particles and liquids in greater amounts also over the entire actuation path, as already disclosed with reference to  FIGS. 4 to 6 . 
     Because it happens every once in a while over the life of a keyboard that aqueous liquids are spilt, a certain resistance of the key modules  100  against the entry of liquids should be ensured at least in the rest position. The switching mechanism, which is the electric contact is such is presently the contactor unit  115  and the contact element  120 , and the components for guiding the tappet  105 , in particular the compression spring  125  and the wings  110  and the recesses  900 , which would lead to loss of operability of the key module  100  in the case of conglutination, are particularly sensitive to water or sugary liquids, such as coke. For example, the robustness of the key module  100  is improved significantly by introducing a labyrinth seal as sealing element  150  between the cover element  110  and the housing element  130  acting as a base. The labyrinth seal as sealing element  150  protects the entire switching mechanism, which is the contactor unit  115  and the contact element  120 , and the components for the guidance of the tappet  150 , as already described with reference to  FIGS. 1 and 9 , against the entry of liquids, such as water or sugary drinks, and dust in harmful amounts. The aqueous liquids are stopped in the labyrinth seal as sealing element  150  by capillary action so that they do not enter the key module  100 . 
     In certain customer applications, it is desired that the keyboards comprise reduced noise development. Presently, in MX Silent modules of the applicant, for example, costly two-component technology is used. Soft damper elements are sprayed in at certain locations here, in order to reduce noise development in the case of an impact of components to these parts. The manufacture of such a key module  100  thus is very expensive, limited in the selection of materials and requires special tools and processes. 
     In the approach presented here, a key module  100  is presented in which this issue is provided for by additionally installing a rubber profile as shock absorber element  230  (for example in a round, square, etc. . . . shape) as a damper element in the centering stud as guiding piston  235 , for example. 
       FIG. 15  shows a perspective illustration of a housing element  130  with the sealing element  150 , the shock absorber element  230 , the guiding piston  235  and further components previously mentioned. The shock absorber element  230  may be formed as a rubber damper and may be prefabricated as an endless profile, for example, and cut to the desired length and installed in the guiding piston  235 . Optionally, the damper element or shock absorber element  230  may be installed as a disc or ring in the guiding piston  235  between the tappet  105  and the housing element  130 . This procedure has several advantages, for example installation may be done according to demand, and no additional tools are needed. Also, a wide selection of materials is available for the shock absorber element  230 , and only small overall costs are accrued for providing such an optional shock absorber element  230 . Furthermore, an inside view of the housing element  130  with the accommodating bowl  175  and the recesses  1100  arranged in the accommodating bowl  175  can be seen, wherein these recesses  1100  here are provided as complete lateral slit-shaped openings in the accommodating bowl  175 . 
       FIG. 16  shows a side view of a key module  100 , which is installed on a circuit board  1600 , such as may be used as a circuit board of a keyboard, for example. 
       FIG. 17  shows a side view of a further key module  100 , which was also installed on a circuit board, wherein the key module  100  further was stuck through another circuit board as an assembly frame  1700  or is held by this assembly frame  1700  during manufacture. The assembly frame  1700  may be used as a retaining circuit board, for example, so as to ensure stable alignment of the key module  100  during the mounting process of the key module  100  on the circuit board  1600 . Here, the assembly frame  1700  can be arranged at a small distance above the circuit board  1600 . 
     Reduced construction of the height of the key modules  100  renders the assembly of frequently required electronic devices (for example SMD-based) on the top side of the circuit board as a carrier of the key modules  100  difficult or impossible, in particular in connection with frame assembly. Assembly of the required devices on the bottom side of such a circuit board also is problematic, because certain devices should be attached directly to the key modules  100 . This results in considerable difficulties in the subsequent key module soldering process (especially when using a solder wave), because all components need to be covered. Moreover, there is the risk of destruction of the electronic devices due to electrostatic discharge (of up to 8 KV). According to embodiments of the approach presented here, placing SMD devices (for example LEDs, diodes; resistors) below the key module  100  on the top side of the circuit board can be provided as a solution of the problem. 
       FIG. 18  shows a perspective view on a key module  100  on the housing element  130 . What can be seen is the electronic devices  1800  of the key module  100 , which are protected mechanically and against electric discharge by the housing element  130  of the key module  100 . A subsequent soldering process can be devised to be inexpensive, because no components need to be placed on the bottom side of the circuit board. The key module  100  can be placed directly on the assembly frame  1700 , as can be seen from the illustration of  FIG. 16 , or be held by means of an additional assembly frame  1700 , as can be seen from  FIG. 17 . In both cases, additional protection against discharge may take place by electrically connecting a protective structure on the top side of the circuit board  1600  or mounting frame  1700  to a ground lead directly or via a discharge resistor (for example 100-300 Ohms). 
     If an embodiment comprises an “and/or” connection between a first feature and a second feature, this may be read to mean that the embodiment comprises both the first feature and the second feature according to one embodiment and either only the first feature or only the second feature according to a further embodiment. 
     REFERENCE NUMERALS 
     
         
           100  key module 
           105  tappet, actuation element 
           110  cover element 
           115  contactor unit 
           120  contact element 
           125  compression spring 
           130  housing element, bottom element 
           135  cam nose 
           140  contact nose 
           145  contact tip 
           150  sealing element 
           160  keycap supporting portion 
           165  guiding portion 
           167  outside 
           170  wing, rib 
           175  accommodating bowl 
           180  hollow-cylindrical portion 
           200  movement axis 
           210  passage area 
           215  opening 
           220  tappet slope 
           225  cover slope 
           230  shock absorber element 
           235  guiding piston 
           400  guiding wall, constructive element 
           410  guiding surface 
           420  cam nose protrusion 
           430  distance limiting element 
           500  surface portion 
           600  strike wall 
           610  strike portion 
           700  reset surface portion 
           900  keycap support ribs 
           1100  recess 
           1210  light guiding element 
           1600  circuit board 
           1700  assembly frame 
           1800  electronic device