Patent Publication Number: US-2023154700-A1

Title: Key module for a keyboard, and keyboard

Description:
The present invention relates to a key module for a keyboard and to a keyboard having at least one such key module. 
     In keyboards, such as ones used in connection with computers, for example, different key systems may be employed. Here, in particular, compression springs or tension springs may be employed as reset mechanism. Such springs key modules may possibly be set to vibration, which in turn may lead to undesirable acoustic properties of keyboards. 
     Against this background, the present invention provides an improved key module for a keyboard and an improved keyboard in accordance with the main claims. 
     Advantageous embodiments are obvious from the dependent claims and the subsequent description. 
     According to embodiments of the approach described here, in particular with respect to a spring of a key module for a keyboard, mechanical vibrations can be dampened, in order to prevent vibrations of the spring body or spring element from developing, and additionally or alternatively in order to dampen or minimize possibly existing vibrations. Such vibration dampening may be realized in at least a portion of an actuation path or key travel path, for example. 
     Advantageously, according to embodiments, in particular, vibrations of springs can be prevented or vibrations already present can be dampened effectively, in order to also avoid development of sound waves. Hence, for example, vibrations of the spring can be dampened, and thus a freely vibrating system due to an elastic spring body can be prevented. Consequently, in particular, energy of mechanical excitation can be transformed to heat through mechanical friction by the dampening device, and conditions conducive to the development of free vibrations can be eliminated. 
     According to embodiments, in particular, a spring body of a compression spring or tension spring can be prevented from being set to vibrations when suddenly loaded or unloaded or when laterally excited, for example. Such mechanical vibrations may occur along a spring body axis as longitudinal vibrations or transversal to the spring body axis as transversal vibrations. Windings of the spring in a middle portion thereof may reach maximum amplitude. By way of the vibration damping, in particular, the vibrations can be prevented from being transformed to acoustic sound waves or from being transmitted to adjoining components, such as housing components or the like, as structure-borne sound. By way of the vibration damping, it can also be avoided that vibrations can act in housing components as acoustic bodies, produce resonances and generate amplified sound waves. Since neighboring key modules or key switches may have almost identical springs, for example, a resonance frequency of all or many of the key module is arranged on the keyboard may be identical. Furthermore, by way of the vibration damping, it can be prevented that vibration transmission to all or several key modules of the keyboard excites the springs thereof, and thus possibly all or many key modules produce sound waves and an overall soundscape would be impaired. 
     A key module for a keyboard is presented, wherein the key module comprises: 
     at least one guide unit formed to guide movement of an actuation unit of the key module between a rest position and an actuated position upon actuation of the key module; 
     at least one spring element for biasing the actuation unit of the key module into the rest position; and 
     means for dampening mechanical vibrations of the spring element at least when the actuation unit is in the rest position. 
     The keyboard may be provided for a computer or the like, for example. The keyboard may comprise at least one key module. The key module may be part of a key or represent a key. Thus, one key module may be provided per key. The key module may also be referred to as a mechanical key module or as a mechanical pushbutton. The at least one spring element may also be referred to as elastic means. In the rest position of the actuation unit, the key module, and thus the key, may be in a non-actuated state. In the actuated position of the actuation unit, the key module, and thus the key, may be in a completely actuated state. An actuation path or key travel path of the key module may extend between the rest position and the actuated position. The rest position and the actuated position may here represent endpoints of the actuation path. The means for dampening may also be referred to as at least one dampening device. The means for dampening may be arranged, configured and additionally or alternatively formed to directly act on the at least one spring element. 
     Also, the means for dampening may be configured to dampen the mechanical vibrations of the spring element during the entire movement of the actuation unit between the rest position at the actuated position. Such an embodiment offers the advantage that the vibrations can be prevented and additionally or alternatively minimized in a particularly reliable and safe way. 
     According to an embodiment, the means for dampening may comprise at least one damper element that may be formed to contact and additionally or alternatively elastically deform at least a portion of the spring element. In particular, the damper element may be formed and additionally or alternatively arranged to contact and additionally or alternatively elastically deform at least a central portion of the spring element arranged between both end portions of the spring element. The at least one damper element may here be attached to at least one component of the key module or integrally formed with at least one component of the key module. Such an embodiment offers the advantage that the vibration damping can be realized in a simple and inexpensive way, without necessitating modification of the spring element. 
     Herein, the key module may comprise a keycap as actuation unit. The spring element may be formed as a tension spring. The guide unit may comprise two wing elements, between which the spring element is stretched in an assembled state of the key module. The keycap may be coupleable or coupled to the wing elements. The damper element may be arranged on the keycap. The guide unit may be configured as a double-wing mechanism. Such an embodiment offers the advantage that spring vibrations in a key module with tension spring and low profile or flat construction height can be dampened effectively. 
     Herein, the damper element may be formed as at least one web of the keycap, which extends in a manner offset from a spring body axis of a spring body of the spring element along the spring body axis in an assembled state of the key module. The web may be formed to protrude from the keycap with a web height along actuation axis of the actuation. Here, the web height may be constant along the spring body axis. Alternatively, the web height along the spring body axis may have a maximum in a central region and minima in both end regions of the web. The web may extend over at least a portion of a length of the spring body of the spring element along the spring body axis. Such an embodiment offers the advantage that vibrations of the spring element can be dampened inexpensively, safely and reliably by the web, wherein the required constructive space of the key module remains unaffected thereby. The dampening may also be realized by means of several webs. Here, the webs may contact or elastically deform the spring element from the same side or alternatively from opposite sides. 
     Also, the damper element and the spring element may here be arranged and formed to force the keycap in the rest position unilaterally into abutment against the wing elements of the guide unit in the assembled state of the key module. Thereby, lateral clearance between the keycap and the wing mechanism or guide unit can be eliminated, and possible “clattering” or “rattling” of the keycap in the rest position can be inhibited. 
     Alternatively, the key module may comprise a key tappet as the actuation unit, wherein the key tappet is coupleable or coupled to a keycap, and a housing for at least partially accommodating the spring element and the key tappet. The guide unit may comprise a guide pin of the housing and a guide sleeve of the key tappet. The spring element may be formed as a compression spring. The at least one damper element may be arranged on the housing and additionally or alternatively on the key tappet. The spring element may be arranged between the key tappet and the housing. Such an embodiment offers the advantage that effective vibration damping can be realized also for a key module with a compression spring and a higher profile or greater constructive height. 
     Herein, the at least one damper element may be formed as at least one glide fin, which extends in a manner offset from a spring body axis of a spring body of the spring element along the spring body axis in an assembled state of the key module. Here, the spring body axis may extend along an actuation axis of the actuation. Additionally, audio is or facts can be employed to minimize friction between windings of the spring element and the glide fin. Such an embodiment offers the advantage that vibrations of the spring element can be dampened inexpensively and reliably with a given constructive space of the key module. 
     Furthermore, the at least one damper element may here be formed on the housing, in particular on the guide pin of the housing. The at least one damper element may be formed to contact and additionally or alternatively elastically deform the spring element radially from inside. Additionally or alternatively, the at least one damper element may be formed on the key tappet, in particular on the guide sleeve of the key tappet. The at least one damper element may be formed to contact and additionally or alternatively elastically deform the spring element radially from outside. Such an embodiment offers the advantage that contacting of the spring may take place from the outside or the inside of the spring body, wherein a combination of opposing contacts from the outside and the inside is possible. 
     According to an embodiment, the means for dampening may comprise a medium with which at least the spring element is wetted. The medium may be a gel-like medium, a paste-like medium, a liquid or a fatty medium. Upon vibration of individual windings of the spring element, this medium may repeatedly be accelerated and decelerated in opposite directions, wherein the medium may repeatedly be plastically formed due to the moment of inertia, which requires energy. Thus, a transformation of energy can be achieved from mechanical vibration energy to thermal energy, wherein the vibrations may decay very quickly. In addition, the medium may also be applied between the spring element and the guide pin and additionally or alternatively between the spring element and the guide sleeve, for example. Through winding movement of windings of the spring element, medium located there may be formed continuously, and the vibration energy may be dampened additionally. 
     According to an embodiment, the means for dampening may comprise a material layer with which the spring element is coated at least partially. The material layer may comprise a material having tensile strength lower than tensile strength of a material of the spring element. If a spring wire of the spring element is coated with a material having high internal friction or with a material having low tensile strength, in particular of tin, zinc, copper, silver, plastic or silicone, this may lead to the formation of the coating with each vibration, wherein internal friction may be produced, vibration energy may be transformed to thermal energy, and vibrations may decay. The coating of the spring element may also be realized such that the material layer forms a sheathing around the spring wire of the spring element. Relative movement may occur between the outer sheathing and the spring wire, wherein vibration energy may be reduced and free vibrations may decay due to frictional force between sheathing and wire. 
     What is also presented is a keyboard, wherein the keyboard comprises: 
     at least one exemplar of an embodiment of the key module mentioned herein; and 
     A circuit substrate, wherein the at least one key module is arranged on the circuit substrate. 
     Thus, at least one key module mentioned herein may be employed or used in connection with the keyboard. The at least one key module may be attached directly to the circuit substrate, for example by means of soldering or plugging contact pins in. 
     The invention shall be explained in greater detail by way of example on the basis of the attached drawings, in which: 
    
    
     
         FIG.  1    shows a schematic illustration of a keyboard with key modules, according to an embodiment of the present invention; 
         FIG.  2    shows a partially exploded view of a key module, according to an embodiment of the present invention; 
         FIG.  3    shows a partially sectional illustration of the key module of  FIG.  2   ; 
         FIG.  4    shows an oblique bottom view of the keycap of the key module of  FIG.  2    or  FIG.  3   ; 
         FIG.  5    shows an oblique bottom view of parts of the key module of  FIG.  2    or  FIG.  3   ; 
         FIG.  6    shows a partially sectional illustration of the key module of  FIG.  2   ,  FIG.  3    or  FIG.  5   ; 
         FIG.  7    shows a partially sectional illustration of the key module of  FIG.  2   ,  FIG.  3   ,  FIG.  5    or  FIG.  6   ; 
         FIG.  8    shows a partially sectional illustration of a key module, according to an embodiment of the present invention; 
         FIG.  9    shows a partially sectional illustration of the key module of  FIG.  8   ; 
         FIG.  10    shows a partially sectional illustration of the key module of  FIG.  8    or  FIG.  9   ; 
         FIG.  11    shows an oblique top view onto a housing part of the key module of  FIG.  8   ,  FIG.  9    or  FIG.  10   ; 
         FIG.  12    shows an oblique bottom view of the key tappet of the key module of  FIG.  8   ,  FIG.  9    or  FIG.  10   ; 
         FIG.  13    shows a partially sectional illustration of a spring element of a key module, according to an embodiment of the present invention; 
         FIG.  14    shows a partially sectional illustration of the spring element of  FIG.  13   ; 
         FIG.  15    shows a partially sectional illustration of a spring element of a key module, according to an embodiment of the present invention; and 
         FIG.  16    shows a detail of the spring element from  FIG.  15   . 
     
    
    
     In the subsequent description of preferred embodiments of the present invention, the same or similar reference numerals shall be used for the similarly acting elements depicted in the various figures, wherein repeated description of these elements shall be omitted. 
       FIG.  1    shows a schematic illustration of a keyboard  100  with key modules  120 , according to an embodiment. The keyboard  100  is part of a notebook computer, laptop computer or the like, for example. Alternatively, the keyboard  100  also is configured as a peripheral device for a computer, in particular. 
     The keyboard  100  comprises a circuit substrate  110 . The circuit substrate  110  is a circuit board, conductor board or the like, for example. According to the embodiment illustrated in  FIG.  1   , the keyboard  100  comprises a plurality of key modules  120 . The key modules  120  are arranged on the circuit substrate  110 . Here, the key modules  120  are soldered onto the circuit substrate  110 , for example. 
     Furthermore, according to the embodiment shown and described in  FIG.  1   , a keycap  125  is attached to each key module  120 . Here, each keycap  125  is coupled to a key module  120  of its own. Each unit of key module  120  keycap  125  represents a key of the keyboard  100 . Alternatively, each key module  120  represents a key of the keyboard  100 . Particularly the key modules  120  shall be explained in greater detail with reference to subsequent figures. 
     The keycap  125  represents a part of a key that is visible and touchable for a user of the keyboard  100 . Actuation of a key module  120  is effected by pressing onto the keycap  125 . Each key module  120  is configured to react to an actuation force with a force-path characteristic of resistance or a reset force by at least one spring element. Furthermore, each key module  120  is configured to establish an electrical connection responsive to actuation with a pre-definable actuation path, wherein a switching process is executed. 
       FIG.  2    shows a partially exploded view of a key module  120 , according to an embodiment of the present invention. The key module  120  here corresponds to or is similar to one of the key modules from  FIG.  1   . The key module  120  comprises a guide unit  230  formed to guide movement of an actuation unit of the key module  120  between a rest position and in an actuated position upon actuation of the key module  120 . Furthermore, the key module  120  comprises a spring element  140  for biasing the actuation unit of the key module  120  into the rest position. Even though not visible in  FIG.  2    for illustrative reasons, the key module  120  also comprises means for dampening mechanical vibrations of the spring element  140  at least when the actuation unit is in the rest position. 
     According to the embodiment illustrated in  FIG.  2   , the key module  120  also comprises the keycap  125 . The keycap  125  here functions as actuation unit. The spring element  240  is formed as a tension spring. The guide unit  230  comprises two wing elements, between which the spring element  240  is stretched in an assembled state of the key module  120 . The keycap  125  is coupleable to the wing elements. In a state in which the keycap  100  to  25  is mounted to the key module  120 , the key module  120  and the keycap  125  represent a key. At least one alphanumerical character or special character is printed on the keycap  125 . 
     According to the embodiment illustrated in  FIG.  2   , the means for dampening include at least one damper element arranged or formed on the keycap  125 . The means for dampening or the damper element shall be explained in greater detail in the following with reference to subsequent figures. 
     The key module  120  comprises a first wing element and a second wing element as actuation unit  230  for guiding a movement of the key module  120  upon actuation by a user. The two wing elements are mechanically coupled to each other. In the illustration of  FIG.  2   , the wing elements are shown in a non-actuated state of the key module  120 . In the non-actuated state, the wing elements mechanically coupled to each other span an obtuse resting angle between themselves. In an actuated state of the key module  120 , the wing elements coupled to each other span an opening angle greater than the resting angle between themselves. The opening angle may also be 180 degrees. A difference between the resting angle and the opening angle may range from about 12 degrees to 18 degrees, for example. 
     Each wing element of the guide unit  230  comprises a bar, a first arm and a second arm. The arms extend away from the bar. In particular, the arms extend away from the bar at right angles. Also, the arms extend in parallel with respect to each other within a tolerance range, for example. Alternatively, the arms may also extend obliquely with respect to each other. According to the embodiment illustrated in  FIG.  2   , the first wing element and the second wing element are formed to be identical with each other. In addition, each wing element is integrally formed here. For example, each wing element is also formed of a metal material. 
     According to the embodiment shown and described in  FIG.  2   , each of the wing elements of the guide unit  230  comprises two mounting portions for mounting the spring element  240  and two bearing portions for bearing the wing element, for example. The mounting portions are formed on the bar of the wing element. The mounting portions are formed as through-holes, particularly as rounded triangular through-holes, in the wing element. The bearing portions are formed on the arms of the wing element. A first bearing portion is formed on the first arm, and a second bearing portion is formed on the second arm. The bearing portions are formed as ledges, steps or noses in outside edges of the arms of the wing element. 
     Each wing element of the guide unit  230  also comprises at least one connecting portion for connecting the wing element to the keycap  125 . According to the embodiment illustrated in  FIG.  2   , each wing element comprises one connecting portion, for example. The connecting portion is formed on the bar of the wing element. The keycap  125  is connectable to the wing elements via a snap-fit by means of the connecting portions. 
     The spring element  240  is formed to provide a reset force upon actuation of the key module  120 . According to the embodiment illustrated in  FIG.  2   , the key module  120  comprises one spring element  240 , for example. The spring element  240  is mounted to one of the mounting portions of the first wing element and two one of the mounting portions of the second wing element. Here, the spring element  240  is configured as a tension spring. 
     The key module  120  also comprises a support element  250  for supporting the wing elements of the guide unit  230 . The support element  250  is also formed to support the spring element  240  and the keycap  125  when they are attached to the wing elements  230 . For example, the support element  250  is formed of a metal material. The support element  250  comprises a plurality of accommodating portions for accommodating the bearing portions of the wing elements. According to the embodiment shown and described in  FIG.  2   , the support element  250  here comprises four accommodating portions. The accommodating portions are formed as bearing grooves in the support element  250 . In other words, the accommodating portions are formed to be groove-shaped, v-shaped or swallow-tailed. The bearing portions of the wing elements are supported in the accommodating portions in a mounted state of the key module  120 . Thus, the wing elements are supported on the support element  250  so as to be pivotable or tiltable in a pre-definable angle range. The angle range is also definable by a shape of the accommodating portions. 
     Moreover, the key module  120  comprises a switch unit  260 . The switch unit  260  comprises a housing and a contact device. The contact device is at least partially arranged in the housing. In other words, the housing is formed to accommodate at least a portion of the contact device. According to the embodiment shown in  FIG.  2   , for example only one groove for accommodating at least a portion of the spring element  240  in an actuated state of the key module  120  is formed in the housing. The contact device is configured to establish electric contact in the course of actuation of the key module  120 . The contact device can be pressed or deformed by the keycap  125 , for example, in order to effect the establishment of the electric contact. 
       FIG.  3    shows a partially sectional illustration of the key module  120  of  FIG.  2   . The keycap  125  with a cam  328 , the spring element  240  and the damper element  315  are shown of the key module  120  in  FIG.  3   . The damper element  315  is arranged on the keycap  125 , more specifically it is formed as a part thereof. According to the embodiment illustrated here, the damper element  315  is formed adjacent to the cam  328  or as part of the cam  328 . The damper element  315  is formed and arranged to contact and/or elastically deform at least a portion of the spring element  240 . According to an embodiment, the means for dampening or the damper element  315  is configured to dampen the mechanical vibrations of the spring element  240  over the entire movement of the actuation unit, here particularly the keycap  125 , between the rest position and the actuated position. 
     The cam  328  is formed as a portion of the keycap  125 . More specifically, the cam  328  is formed as a portion of the keycap  125  protruding toward the spring element  240 . The cam  328  is formed to deform, more specifically to elastically deform, the spring element  240  in an actuated state of the key module  120 . With increasing actuation path during actuation of the key module  120 , the spring element  240  is deformable by the cam  328 . Here, the cam  328  is formed and arranged to bend the spring element  240 . When being bent by the cam  328 , spring force of the spring element  240  loses linearity, with a reset force acting against an actuation force or a resistance acting against an actuation force increasing due to the deformed spring element  240 . 
       FIG.  4    shows an oblique bottom view of the keycap  125  of the key module of  FIG.  2    or  FIG.  3   . Here, the damper element  315  is shown, in particular. Furthermore, the cam  328  is shown. According to the embodiment illustrated here, the damper element  315  is formed as at least one web of the keycap  125 , extending in a manner offset from a spring body axis of a spring body of the spring element  240  along the spring body axis in an assembled state of the key module  120 . 
       FIG.  5    shows an oblique bottom view of parts of the key module  120  of  FIG.  2    or  FIG.  3   . The keycap  125 , the guide unit  230 , the spring element  240 , the support element  250  and the damper element  315  are shown of the key module  120  in  FIG.  5   . 
       FIG.  6    shows a partially sectional illustration of the key module  120  of  FIG.  2   ,  FIG.  3    or  FIG.  5   . The keycap  125 , the guide unit  230 , the spring element  240  and the damper element  315  are shown of the key module  120  in  FIG.  6   . It can also be seen that the damper element  315  contacts the spring element  240 . 
       FIG.  7    shows a partially sectional illustration of the key module  120  of  FIG.  2   ,  FIG.  3   ,  FIG.  5    or  FIG.  6   . The illustration in  FIG.  7    here corresponds to the illustration of  FIG.  6   , except that arrows representing further interaction between the damper element  315  and the spring element  240  are depicted additionally. The further interaction consists in the keycap  125  being forced out of center in the rest position by the spring element  240  and the damper element  315 . Here, the damper element  315  and the spring element  240  are arranged and formed to force the keycap  125  in the rest position into unilateral abutment against the wing elements of the guide unit  230 . In other words, the guide areas of the wing elements of the guide unit  230  are pressed against a side wall of the keycap  125 , more specifically a sidewall illustrated at the bottom in  FIG.  7   . Thereby, a lateral clearance between keycap  125  and wing mechanism or guide unit  230  can be eliminated, and possible “clattering” or “rattling” of the keycap  125  in the rest position can be inhibited. 
     With reference to  FIGS.  2  to  7   , it is to be noted that the damper element  315  can prevent the spring element  240 , which is configured as a tension spring here, from being excited transversally to the spring axis in the case of a sudden switch back or a sudden movement from the direction of the actuated position toward the rest position, and from transferring the vibrations to the keycap  125  or housing components of a keyboard, where they could otherwise be transformed into sound waves. The vibration damping is achieved by the fact that the spring windings, particularly the central windings, of the spring element  240  are in mechanical contact with the damper element  315 , which is configured as a web in the keycap  124 , during the entire actuation path of the key module  120 , for example. 
       FIG.  8    shows a partially sectional illustration of a key module  120  according to an embodiment of the present invention. The key module  120  here corresponds to or is similar to one of the key modules from  FIG.  1   . The key module  120  comprises a guide unit  832 ,  834 , which is formed to guide movement of an actuation unit of the key module  120 , which is configured as a key tappet  825 , between a rest position and in actuated position when the key module  120  is being actuated. Furthermore, the key module  120  comprises a spring element  140  for biasing the actuation unit  825  of the key module  120  into the rest position. Even though it is not shown explicitly in  FIG.  8   , the key module  120  also comprises means for dampening mechanical vibrations of the spring element  240  at least when the actuation unit is in the rest position. According to the embodiment illustrated here, the means for dampening comprise at least one damper element, which is formed to contact and/or elastically deform at least a portion of the spring element  240 . In particular, the means for dampening are configured to dampen the mechanical vibrations of the spring element  240  over the entire movement of the key tappet  824  between the rest position and the actuated position. 
     The key tappet  825  functions as actuation unit. The key tappet  825  is coupleable to a keycap. The key module  120  also comprises a housing of a housing lid  852  and a housing base  854  for at least partially accommodating the spring element  240  and the key tappet  824 . The spring element  240  is formed as a compression spring. The guide unit of the key module  120  includes a guide pin  834  of the housing, more specifically of the housing base  854 , and a guide sleeve  832  of the key tappet  825 . Guiding the movement of the key tappet  825  relative to the housing  852 ,  854  results from engagement of the guide sleeve  832  and guide pin  834 . The at least one damper element is arranged on the housing, more specifically the housing base  854 , and/or on the key tappet  825 . 
     The means for dampening or the at least one damper element shall be explained in greater detail in the following with reference to subsequent figures.  FIG.  8    depicts two arrows illustrating possible regions of interaction between the means for dampening and the spring element  240 . 
       FIG.  9    shows a partially sectional illustration of the key module  120  of  FIG.  8   . The key module  120  in  FIG.  9    here corresponds to or is similar to the key module from  FIG.  8   . In addition to the elements of the key module  120  illustrated in  FIG.  8   ,  FIG.  9    also shows a damper element or tappet-side damper element  915 . The tappet-side damper element  915  is formed on the key tappet  825 , more specifically on the guide sleeve  832  thereof. The tappet-side damper element  915  is formed to contact and/or elastically deform the spring element  240  radially from outside or from without. 
       FIG.  10    shows a partially sectional illustration of the key module  120  of  FIG.  8    or  FIG.  9   . The key module  120  in  FIG.  10    here corresponds to or is similar to the key module from  FIG.  8   . Additionally or alternatively to the tappet-side damper element shown in  FIG.  9   , the key module  120  includes another damper element or housing-side damper element  1015 . The housing-side damper element  1015  is formed on the housing  852 ,  854 , more specifically on the guide pin  834 . The housing-side damper element  1015  is formed to contact and/or elastically deform the spring element  240  radially from inside or from within. 
       FIG.  11    shows an oblique top view onto a housing component of the key module of auf  FIG.  8   ,  FIG.  9    or  FIG.  10   . The housing component shown in  FIG.  11    is the housing base  854 . Furthermore,  FIG.  11    illustrates the guide pin  834  and the housing-side damper element  1015 . The housing-side damper element  1015  is formed as a glide fin, which extends in a manner offset from a spring body axis of a spring body of the spring element along the spring body axis in an assembled state of the key module. 
       FIG.  12    shows an oblique bottom view of the key tappet  825  of the key module of  FIG.  8   ,  FIG.  9    or  FIG.  10   .  FIG.  12    further illustrates the guide sleeve  832  and the tappet-side damper element  915 . The tappet-side damper element  915  is formed as a glide fin, which extends in a manner offset from a spring body axis of a spring body of the spring element along the spring body axis in an assembled state of the key module. 
     With reference to  FIGS.  8  to  12   , it is to be noted that the vibration damping can also be realized in a reliable manner in a mechanical key module  120  having a compression spring as the reset element or spring element  240 . In particular, the difference is that the individual windings of the spring element  240  are set to vibrate in the direction of the spring body axis upon sudden actuation or switch-back. In such a key module  120 , there is radial contact or elastic deformation of the spring body of the spring element  240  with a damper element  915  and/or  1015  formed as a glide element, in particular over the entire actuation path. Here, oils or fats may additionally be employed for minimizing wear. The spring may be contacted from the outside or from the inside of the spring body. For example, the guide pin  834  of the housing may be provided with at least one glide fin  1015 , which elastically deforms the spring body or at least the central windings of the spring element  240  radially from inside. The glide fin  915  may also be placed in the guide sleeve  832 , in this case in the key tappet  825 , so as to contact the spring body from outside. A combination of opposing contacts from outside and inside is also conceivable. 
       FIG.  13    and  FIG.  14    shows a partially sectional illustration of a spring element  240  of a key module according to an embodiment of the present invention. The spring element  240  is the spring element from one of the previously described figures or a similar spring element. What is shown as means for dampening is a medium  1315  with which the spring elements  240  is wetted. The medium  1315  is a gel-like medium, a paste-like medium, a liquid or a fatty medium. 
     The spring body of the spring element  240  is wetted with a gel-like medium  1315 , e.g. fat. The medium  1315  has a viscosity such that the medium  1315  adheres well to the spring windings and does not dry out. When the individual windings vibrate, this medium  1315  is repeatedly accelerated and decelerated in opposite directions, as symbolically illustrated by way of arrows in  FIG.  13    and  FIG.  14   . Owing to the moment of inertia, the medium  1315  is repeatedly plastically formed. Energy is required for the forming. Thus, there is energy transformation from mechanical vibration energy to thermal energy. Vibrations of the spring element  240  decay very quickly here. Additionally, the medium  1315 , for example the gel-like medium, may also be placed between the spring element  240  and the guide pin or the guide sleeve from one of  FIGS.  8  to  12   . Through the winding movement, medium  1315  located there is continuously formed, and the vibration energy is dampened in addition. 
       FIG.  15    shows a partially sectional illustration of a spring element  240  of a key module according to an embodiment of the present invention. The spring element  240  is the spring element from one of the previously described figures or a similar spring element. A material layer  1515  with which the spring element  240  is at least partially coated is shown as the means for dampening. The material layer  1515  comprises a material having a tensile strength lower than a tensile strength of a material of the spring element  240 . Furthermore, a detail  1505  is marked in  FIG.  15   . 
       FIG.  16    shows the detailed  1505  of the spring element  240  and of the material layer  1515  from  FIG.  15   . According to the embodiment illustrated in  FIG.  15    and  FIG.  16   , the spring element  240  is coated completely with the material layer  1515 . 
     The spring element  240 , which consists of a hard material, e.g. spring steel, is elastically deformed repeatedly by actuation. Due to low internal friction, vibrations may persist for a long time and produce acoustic noise. The wire of the spring element  240  here is stressed with torsion or stressed with rotation. The stress increases concentrically from the center of the wire to the outer skin. This means that material regions on the outer surface of the wire are stressed and deformed the most. If the spring wire of the spring element  240  is coated with a material having high internal friction or a material having low tensile strength, this leads to deformation, particularly plastic deformation, of the material layer  1515  with every vibration. Deformation produces internal friction, the vibration energy is transformed to thermal energy, and the vibrations decay. The material layer  1515  may also be realized such that it forms a coat around the spring wire of the spring element  240 . There will then be relative movement between outer coat or material layer  1515  and the spring wire. The frictional force between coat and wire will also decrease the vibration energy and let free vibrations decay. 
     Where an embodiment comprises an “and/or” connection between a first feature and a second feature, this can be read such that the embodiment comprises both the first feature and the second feature according to a first variant and either the first feature or the second feature only according to a further variant. 
     REFERENCE NUMERALS 
     
         
           100  keyboard 
           110  circuit substrate 
           120  key module 
           125  keycap 
           230  guide unit 
           240  spring element 
           250  support element 
           260  switch unit 
           315  damper element 
           328  cam 
           825  key tappet 
           832  guide sleeve 
           834  guide pin 
           852  housing lid 
           854  housing base 
           915  tappet-side damper element 
           1015  housing-side damper element 
           1315  medium 
           1505  detail 
           1515  material layer