Patent Publication Number: US-9412535-B2

Title: Keyswitch structure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a keyswitch structure, and especially relates to a mechanical keyswitch structure. 
     2. Description of the Prior Art 
     A stroke of a keycap of conventional keyswitches is relatively long, so it is easy to dispose a rubber dome under the keycap so that when the keycap is pressed to move downward, the rubber dome is also deformed and produces resilient force, and when the keycap is released, the resilient force drives the keycap to move upward to its original position. However, with a tendency toward keyboard miniaturization, the stroke of the keycap is required to decrease, so the height of the rubber dome is also required to lower. The service life and the character of resilient force will decay with a height of the rubber dome decreasing. Furthermore, for a keyswitch with a longer length (or called a multiple-width keyswitch), a plurality of links are disposed under the keycap so that the keycap can keep being horizontally moved up and down when a user presses any portion of the keycap, and the user can feel a distinct force feedback (or tactile feedback). However, if the height of the keycap is required to decrease more, the above design may not be accomplished easily due to space constraint. 
     SUMMARY OF THE INVENTION 
     An objective of the invention is to provide a keyswitch structure that uses a magnetic attraction force in cooperation with supports with lever structure to produce stable movement of the keycap and further distinct and stable tactile feedback when pressing the keycap. 
     In an embodiment, a keyswitch structure according to the invention includes a base, a keycap, a lift mechanism, and a first magnetic member. The lift mechanism is disposed between the base and the keycap. The keycap is capable of moving up and down in a vertical direction relative to the base through the lift mechanism. The lift mechanism includes a first support. The first support has a first side edge portion, a second side edge portion, and a first magnetic portion. The first side edge portion keeps abutting against the base through a sharp edge. The second side edge portion is opposite to the first side edge portion and movably connected with the keycap. The first magnetic portion extends outward from the first side edge portion. The first magnetic member is disposed on the base corresponding to the first magnetic portion. The first magnetic member and the first magnetic portion produce a magnetic attraction force therebetween. Thereby, when the keycap is pressed by an external force, the first support rotates about the sharp edge relative to the base, so that the first magnetic portion moves away from the first magnetic member and the keycap approaches the base. Therein, the magnetic attraction force decreases as the first magnetic portion moves away from the first magnetic member, which facilitates the keycap approaching the base. When the external force is eliminated, the magnetic attraction force drives the first support to rotate (i.e. reversely rotate) about the sharp edge relative to the base so that the second side edge portion of the first support makes the keycap move away from the base. 
     In another embodiment, a keyswitch structure according to the invention includes a base, a keycap, a lift mechanism, and a first magnetic member. The lift mechanism is disposed between the base and the keycap. The keycap is capable of moving up and down in a vertical direction relative to the base through the lift mechanism. The lift mechanism includes a first support and a second support. The first support has a first side edge portion, a second side edge portion, and a first magnetic portion. The first side edge portion keeps abutting against the base. The second side edge portion is opposite to the first side edge portion and movably connected to the keycap. The first magnetic portion extends outward from the first side edge portion. The second support is disposed opposite to the first support. The second support has a third side edge portion and a fourth side edge portion. The third side edge portion keeps abutting against the base. The fourth side edge portion is opposite to the third side edge portion and movably connected to the keycap. The first magnetic member is disposed on the base corresponding to the first magnetic portion. The first magnetic member and the first magnetic portion produce a magnetic attraction force therebetween. Thereby, when the keycap is pressed by an external force, the first support rotates about the first side edge portion relative to the base, so that the first magnetic portion moves away from the first magnetic member and the keycap approaches the base. Therein, the magnetic attraction force decreases as the first magnetic portion moves away from the first magnetic member, which facilitates the keycap approaching the base. When the external force is eliminated, the magnetic attraction force drives the first support to rotate (i.e. reversely rotate) about the first side edge portion relative to the base so that the second side edge portion of the first support makes the keycap move away from the base. 
     In another embodiment, a keyswitch structure according to the invention includes a base, a keycap, a lift mechanism, and a second magnetic member. The lift mechanism is disposed between the base and the keycap. The keycap is capable of moving up and down in a vertical direction relative to the base through the lift mechanism. The lift mechanism includes a first support. The first support has a first side edge portion, a second side edge portion, and a second magnetic portion. The first side edge portion keeps abutting against the base. The second side edge portion is opposite to the first side edge portion and movably connected to the keycap. The second magnetic member is disposed corresponding to the second magnetic portion on the base under the first side edge portion. Therein, the second magnetic portion and the second magnetic member produce a magnetic attraction force therebetween for driving the first side edge portion to abut against the base so that the first support can rotate relative to the base through the first side edge portion stably. 
     Compared with the prior art, the keyswitch structure according to the invention uses the magnetic attraction force as a driving force for returning the keycap to its original position without a rubber dome and a link bar, so a disposition space for the keyswitch structure can be reduced and the keyswitch structure can be compact, which is conducive to a reduction of the height of the keyswitch structure. Furthermore, in the keyswitch structure according to the invention, the support uses its sharp edge to abut against the base and rotates about the sharp edge, so the support can stably and precisely rotate relative to the base and a rotation friction is reduced, which provides a user distinct and stable tactile feedback when pressing the keycap. In addition, when the keyswitch structure according to the invention is applied to a keyswitch with a longer length (or called a multiple-width keyswitch), the keycap of keyswitch structure has a longer length, and the first side edge portion and the second side edge portion of the first support are also longer. In principle, the constraint effect by the magnetic attraction force between the first magnetic member and the first magnetic portion on the first side edge portion (i.e. driving the first side edge portion to keep abutting against the base) weakens with a distance to the first magnetic member (or the first magnetic portion) increasing, but the whole first side edge portion still can keep abutting against the base by the magnetic attraction force between the second magnetic member and the second magnetic portion, so that the first support (especially the two end portions) will not be deformed or bent. Thereby, no matter which portion of the keycap an external force is applied to, the keycap makes the first support rotate about the first side edge portion relative to the base through the second side edge portion, so that the magnetic portion moves away from the magnetic member and the keycap approaches the base steadily. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram illustrating a keyswitch structure of an embodiment according to the invention. 
         FIG. 2  is an exploded view of the keyswitch structure in  FIG. 1 . 
         FIG. 3  is a partially-exploded view of the keyswitch structure in  FIG. 1 . 
         FIG. 4  is a sectional view of the keyswitch structure along the line X-X in  FIG. 3 . 
         FIG. 5  is another sectional view of the keyswitch structure along the line Y-Y in  FIG. 3 . 
         FIG. 6  is a sectional view of the keyswitch structure in  FIG. 4  with the keycap having been pressed. 
         FIG. 7  is a sectional view of the keyswitch structure in  FIG. 5  with the keycap having been pressed. 
         FIG. 8  is a sectional view of the keyswitch structure along the line Z-Z in  FIG. 3 . 
         FIG. 9  is a partially-exploded view of a keyswitch structure of another embodiment according to the invention. 
         FIG. 10  is an exploded view of a keyswitch structure of another embodiment according to the invention. 
         FIG. 11  is a sectional view of the keyswitch structure in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIGS. 1-5 .  FIG. 1  is a schematic diagram illustrating a keyswitch structure  1  of an embodiment according to the invention.  FIG. 2  is an exploded view of the keyswitch structure  1 .  FIG. 3  is a partially-exploded view of the keyswitch structure  1 .  FIG. 4  is a sectional view of the keyswitch structure  1  along the line X-X in  FIG. 3 .  FIG. 5  is another sectional view of the keyswitch structure  1  along the line Y-Y in  FIG. 3 . The keyswitch structure  1  includes abase  10 , a keycap  12 , a lift mechanism  14 , a first magnetic member  16 , and two second magnetic members  18 . The keycap  12  is disposed above the base  10 . The lift mechanism  14  is disposed between the base  10  and the keycap  12 , so that the keycap  12  is capable of moving up and down in a vertical direction D 1  relative to the base  10  through the lift mechanism  14 . The first magnetic member  16  and the second magnetic members  18  are disposed on the base  10 . The first magnetic member  16  and the second magnetic members  18  respectively can produce a magnetic attraction force F 1  (indicated by a solid line segment with an arrow in  FIG. 4 ) to the lift mechanism  14  for stabilizing the movement of the lift mechanism  14  so that the keycap  12  can steadily move up and down relative to the base  10 . 
     Further, in the embodiment, the base  10  includes a bottom plate  102 , a membrane circuit board  104 , and an abutting plate  106 . The first magnetic member  16  and the second magnetic members  18  are disposed on the bottom plate  102 . The membrane circuit board  104  is disposed on the bottom plate  102  and has two switches  104   a  and  104   b  (represented by hatched circles). The abutting plate  106  is stacked on the membrane circuit board  104  for the lift mechanism  14  to abut against. The abutting plate  106  also increases the abutting area of the lift mechanism  14  and the base  10 , which is conducive to avoidance of the lift mechanism  14  structurally interfering with the first magnetic member  16  and the second magnetic members  18  when in operation. 
     The lift mechanism  14  includes a first support  142  and a second support  144 . The first support  142  and the second support  144  are oppositely disposed on the base  10 . The first support  142  has a first side edge portion  1422 , a second side edge portion  1424 , and a first magnetic portion  1426 . The first side edge portion  1422  has a sharp edge  1422   a  and keeps abutting against the abutting plate  106  of the base  10  through the sharp edge  1422   a . The second side edge portion  1424  is opposite to the first side edge portion  1422  and movably connected to a bottom surface  12   a  of the keycap  12 . The first magnetic portion  1426  extends outward from the first side edge portion  1422 , i.e. extending in a direction opposite to the second side edge portion  1424 . The second support  144  has a third side edge portion  1442 , a fourth side edge portion  1444 , and an abutting portion  1446 . The third side edge portion  1442  keeps abutting against the abutting plate  106  of the base  10 . The fourth side edge portion  1444  is opposite to the third side edge portion  1442  and movably connected to the bottom surface  12   a  of the keycap  12 . The abutting portion  1446  extends outward from the third side edge portion  1442 , i.e. extending in a direction opposite to the fourth side edge portion  1444 . The abutting portion  1446  is located between the first magnetic portion  1426  and the base  10  and used for abutting against the first support  142 . Furthermore, it is added that the movable connections of the keycap  12  with the second side edge portion  1424  and the fourth side edge portion  1444  are not limited to a case that the second side edge portion  1424  and the fourth side edge portion  1444  are structurally engaged with the keycap  12 . In practice, any connection that makes the keycap  12  move up and down as the lift mechanism  14  moves when the keyswitch structure  1  acts (e.g. a user presses the keycap  12 ) is practicable. In the embodiment, the keycap  12  is not provided with any specific structure for engaging with the lift mechanism  14 , but directly placed on the lift mechanism  14 . The second side edge portion  1424  and the fourth side edge portion  1444  individual contact the bottom surface  12   a  of the keycap  12 . When the keycap  12  moves up and down relative to the base  10  through the lift mechanism  14 , the second side edge portion  1424  and the fourth side edge portion  1444  slide on the bottom surface  12   a.    
     The first magnetic member  16  is disposed on the bottom plate  102  of the base  10  corresponding to the first magnetic portion  1426 , i.e. between the first support  142  and the second support  144 . The first magnetic member  16  and the first magnetic portion  1426  produce the magnetic attraction force F 1  therebetween (indicated by a solid line segment with an arrow in  FIG. 4 ). In practice, the first magnetic member  16  can be a magnet while the first magnetic portion  1426  can be provided with a portion of magnet or be made of paramagnetic material or other material capable of producing an induced magnetic field. In the embodiment, the whole first support  142  is a stamping part of paramagnetic ferro-material, so the first magnetic portion  1426  can be attracted directly by the first magnetic member  16 , which implements the above magnetic attraction force F 1 . Under the effect of the magnetic attraction force F 1 , the first magnetic portion  1426  has a tendency to move downward, so that the first magnetic portion  1426  can keep abutting against the abutting portion  1446 . Therefore, when the magnetic attraction force F 1  drives the first magnetic portion  1426  to approach the first magnetic member  16 , the abutting portion  1446  located between the first magnetic portion  1426  and the base  10  sustains a pressing by the first magnetic portion  1426  to move toward the base  10 , so that the first support  142  rotates about the sharp edge  1422   a  relative to the abutting plate  106  of the base  10  and the second support  144  rotates about the third side edge portion  1442  relative to the abutting plate  106  of the base  10 , so that the keycap  12  moves away from the base  10 . It is added that in the embodiment, the abutting portion  1446  abuts against the first magnetic portion  1426 , but the invention is not limited thereto. In other words, that the abutting portion  1446  abuts against the first support  142  shows a structural contact relation, so it is unnecessary for the portions by which the first support  142  and the abutting portion  1446  abut against each other to be magnetic. For example, the abutting portion  1446  is modified to abut against another portion of the first support  142  (e.g. a structure protruding from the first side edge portion  1422  in a direction opposite to the second side edge portion  1424  for the abutting portion  1446  to abut against). 
     In addition, based on  FIG. 4 , when a user presses the keycap  12 , the first magnetic portion  1426  of the first support  142  sustains the magnetic attraction force F 1 , the second side edge portion  1424  sustains the pressing force by the user through the keycap  12 , and the first side edge portion  1422  of the first support  142  sustains a fulcrum supporting force by the abutting plate  106 , so that the first support  142  functions as a lever and provides supporting. When the user presses the keycap  12 , a resilient force received by the user depends on the magnetic attraction force F 1  and distances to the fulcrum of the lever. In the embodiment, the first support  142  takes the sharp edge  1422   a  as the fulcrum for rotation and further for avoidance of rotational friction force, so that the first support  142  provides the keycap  12  relatively fixed distances to the fulcrum, which facilitates the design of the resilient force (i.e. the tactile feedback received by the user). Similarly, in the embodiment, the second support  144  is provided in the same design. The second support  144  keeps abutting against the abutting plate  106  of the base  10  through a sharp edge  1442   a  of the third side edge portion  1442 , but the invention is not limited thereto. It is added that in the embodiment, the first support  142  and the second support  144  extend in a horizontal direction D 2  (perpendicular to the vertical direction D 1 ). The sharp edges  1422   a  and  1442   a  are structural edges of the first support  142  and the second support  144  extending in the horizontal direction D 2  respectively. Although the first support  142  and the second support  144  form other structures (e.g. the first magnetic portion  1426  and the abutting portion  1446 ) with breaking the edges into a plurality of edge segments, the edge segments all can be regarded as the sharp edges  1422   a  and  1442   a  and in logic the two sets of the plurality of edge segments can be regarded as the sharp edges  1422   a  and  1442   a  according to the invention. For example, an incomplete hole  1426   a  of the first magnetic portion  1426  and an incomplete hole  1446   a  of the abutting portion  1446  still remain a structural edge as a portion of the sharp edges  1422   a  and  1442   a  respectively; the abutting plate  106  has protrusions  106   a  and  106   b  for the structural edges to abut against. 
     The second magnetic members  18  are oppositely disposed on the bottom plate  102  of the base  10  relative to the first magnetic member  16 . The second magnetic members  18  are located between the first support  142  and the second support  144  under the first side edge portion  1422  and the third side edge portion  1442 ; that is, projections of the second magnetic members  18  in the vertical direction D 1  overlap projections of the first support  142  and the second support  144  in the vertical direction D 1 . The first support  142  has two second magnetic portions  1428  (of which the positions are indicated by dashed circles in  FIG. 2 ) facing the second magnetic members  18 . Each pair of one second magnetic portion  1428  and one second magnetic member  18  produce a magnetic attraction force F 2  (indicated by a solid line segment with an arrow in  FIG. 5 ) therebetween. Similarly, the second support  144  has two magnetic portions  1448  (of which the positions are indicated by dashed circles in  FIG. 2 ) facing the second magnetic members  18 . Each pair of one magnetic portion  1448  and one second magnetic member  18  produce a magnetic attraction force F 3  (indicated by a solid line segment with an arrow in  FIG. 5 ) therebetween. In the embodiment, each of the first support  142  and the second support  144  is a stamping part of paramagnetic ferro-material, so the magnetic portions  1428  and  1448  are the portions of the first support  142  and the second support  144  facing to the second magnetic members  18 . The magnetic attraction force F 2  can drive the first support  142  to abut against the base  10  through the sharp edge  1422   a . Similarly, the magnetic attraction force F 3  can drive the second support  144  to abut against the base  10  through the sharp edge  1442   a.    
     It is added that the first magnetic member  16  and the second magnetic members  18  are arranged in the horizontal direction D 2 . The first magnetic member  16  is located substantially at the middle of the two second magnetic members  18 . The first magnetic portion  1426  is located at a middle portion of the first side edge portion  1422 . The abutting portion  1446  is located at a middle portion of the third side edge portion  1442 . The symmetric disposition is conducive to the balance of the first support  142  and the second support  144  when sustaining force, and to the movement stability of the lift mechanism  14 . Furthermore, the second magnetic members  18  are also conducive to the sharp edges  1422   a  and  1442   a  abutting against the abutting plate  106 . The second magnetic members  18  are also located between the first support  142  and the second support  144 , which is conducive to the first support  142  and the second support  144  approaching each other. Therefore, as a whole, the lift mechanism  14  is structurally stable in the keyswitch structure  1 . Therein, the first support  142  and the second support  144  can stably and reliably rotate about the sharp edges  1422   a  and  1442   a  respectively relative to the base  10  (or the abutting plate  106 ), so that the keyswitch structure  1  provides the user stable and reliable tactile feedback. 
     Please also refer to  FIG. 6  and  FIG. 7 .  FIG. 6  is a sectional view of the keyswitch structure  1  in  FIG. 4  with the keycap  12  having been pressed.  FIG. 7  is a sectional view of the keyswitch structure  1  in  FIG. 5  with the keycap  12  having been pressed. When the keycap  12  is pressed by an external force (e.g. the user presses the keycap  12  by a finger), the first support  142  rotates about the sharp edge  1422   a  relative to the base  10 , and the first magnetic portion  1426  moves away from the first magnetic member  16 . At the same time, the second support  144  rotates about the sharp edge  1442   a  relative to the base  10 , and the abutting portion  1446  moves away from the base  10 . Hence, the keycap  12  approaches the base  10 , as shown by  FIG. 6  and  FIG. 7 . In the moving down of the keycap  12 , when the first magnetic portion  1426  moves away from the first magnetic member  16 , under the magnetic attraction effect by the second magnetic member  18  (i.e. under the effect of the magnetic attraction force F 3 ), the second support  144  rotates about the sharp edge  1442   a  toward the abutting plate  106 , i.e. closing the abutting plate  106 , so that the abutting portion  1446  can still remain abutting against the first magnetic portion  1426 . Therefore, during the moving down of the keycap  12 , the whole lift mechanism  14  makes the keycap  12  vertically move toward the base  10  steadily. 
     When the external force is eliminated (e.g. the user moves his finger away from the keycap  12 ), the first support  142  and the second support  144  are substantially under only the effect of the magnetic attraction forces F 1 , F 2  and F 3 . Based on the structural design of the embodiment, a moment to the first support  142  produced by the magnetic attraction force F 1  is larger, even much larger than a sum of a moment to the first support  142  produced by the magnetic attraction force F 2  and a moment indirectly to the first support  142  produced by the magnetic attraction force F 3 , so the magnetic attraction force F 2  still can drive the first support  142  to rotate about the sharp edge  1422   a  relative to the abutting plate  106  of the base  10 . Similarly, during a moving up of the keycap  12 , the whole lift mechanism  14  makes the keycap  12  vertically move away from the base  10  steadily. 
     It is added that in the embodiment, the keyswitch structure  1  is substantially a multiple-width keyswitch. The first support  142  and the second support  144  extend in the horizontal direction D 2 , so the keycap  12  can be wholly supported by the support  142  and the second support  144 . Under the effect by the second magnetic members  18 , the first support  142  and the second support  144  can rotate simultaneously in the horizontal direction D 2 , so the keycap  12  can steadily move up and down relative to the base  10 , and the keycap  12  will not obviously tilt when pressed by the user. The first support  142  and the second support  144  respectively have a protrusion  142   a  and  144   a . When the keycap  12  is pressed down, the protrusions  142   a  and  144   a  can trigger the switches  104   a  and  104   b  respectively, as shown by  FIG. 6 . 
     Furthermore, in the embodiment, the base  10  includes two positioning structures  108   a  and  108   b . The first support  142  includes a positioning structure  1430  adjacent to the first magnetic portion  1426  corresponding to the positioning structure  108   a . The second support  144  includes a positioning structure  1450  adjacent to the abutting portion  1446  according to the positioning structure  108   b . The positioning structures  108   a  and  180   b  of the base  10  are engaged with the positioning structures  1430  and  1450  of the first support  142  and the second support  144  respectively, so that the relative position of the first magnetic portion  1426  and the first magnetic member  16  and the relative position of the abutting portion  1446  and the first magnetic portion  1426  can be maintained, so that the interaction between the first magnetic portion  1426 , the first magnetic member  16 , and the abutting portion  1446  can work normally. In the embodiment, each of the positioning structures  108   a  and  180   b  is a pair of protrusions, and each of the positioning structures  1430  and  1450  is a pair of through holes for the protrusions to pass through for the positioning effect of the first magnetic portion  1426  and the abutting portion  1446  relative to the base  10 . 
     In addition, in the embodiment, the base  10  includes two horizontal constraining structures  110   a  and  110   b . The first support  142  includes a constrained structure  1432  corresponding to the horizontal constraining structure  110   a . The constrained structure  1432  is farther from the first magnetic portion  1426  relatively, at least being closer to the two ends of the first support  142  in the horizontal direction D 2  than the second magnetic portion  1428  (corresponding to the second magnetic member  18 ). The second support  144  includes a constrained structure  1452  corresponding to the horizontal constraining structure  110   b . The constrained structure  1452  is farther from the abutting portion  1446  relatively, at least being closer to the two ends of the first support  142  in the horizontal direction D 2  than the magnetic portion  1448  (corresponding to the second magnetic member  18 ). The horizontal constraining structures  110   a  and  110   b  constrain the constrained structures  1432  and  1452  respectively so that the movements of the first support  142  and the second support  144  in the horizontal direction D 2  are limited. In the embodiment, each of the constrained structures  1432  and  1452  includes two protrusions protruding from the first side edge portion  1422   a  and the third side edge portion  1442   a  respectively. The first magnetic portion  1426  and the abutting portion  1446  are constrained between the two protrusions of the constrained structures  1432  and  1452  respectively. Each of the horizontal constraining structures  110   a  and  110   b  includes two blocking parts correspondingly. The two protrusions are located between the two blocking parts correspondingly. The two blocking parts block the two protrusions in the horizontal direction D 2  so that the movements of the first support  142  and the second support  144  in the horizontal direction D 2  is limited. 
     In addition, please also refer to  FIG. 8  which is a sectional view of the keyswitch structure  1  along the line Z-Z in  FIG. 3 ; therein, the keycap  12  is shown by dashed lines when pressed. In the embodiment, relative to the lift mechanism  14 , the keycap  12  is placed directly on the lift mechanism  14 , so the lift mechanism  14  itself does not constrain the keycap  12  in height. But in the embodiment, the base  10  further includes a vertical constraining structure  112 . The keycap  12  includes a constrained structure  122  correspondingly. The vertical constraining structure  112  constrains the constrained structure  122  so that the movement of the keycap  12  in the vertical direction D 1  is limited. Furthermore, the base  10  further includes a vertical guiding structure  114 . The keycap  12  includes a vertical guided structure (i.e. the same structure as the constrained structure  122 ). The vertical guided structure  122  slides limitedly in the vertical guiding structure  114  as the keycap  12  moves up and down in the vertical direction D 1  relative to the base  10 . In the embodiment, the vertical guiding structure  114  has a sliding slot at each side of the base  10  in the horizontal direction D 2 . The vertical guiding structure  114  and the vertical constraining structure  112  are structurally integrated. An end of the sliding slot (i.e. the close end of the sliding slot) can function as the vertical constraining structure  112 , so the constrained structure  122  and the vertical guided structure  122  of the keycap  12  can be integrated into a single structure (i.e. a structure like a block formed at each side of the keycap  12  in the horizontal direction D 2 , sliding in the sliding slot); however, the invention is not limited thereto. It is added that the vertical guided structure  122  only vertically slides in the vertical guiding structure  114 , and the vertical guiding structure  114  also has a horizontally constraining effect on the keycap  12  (i.e. constraining the movements in the vertical direction D 1  and the vertical direction D 1  of the keycap  12 ). In addition, in the embodiment, the positioning structures  108   a  and  108   b , the horizontal constraining structures  110   a  and  110   b , the vertical constraining structure  112 , and the vertical guiding structure  114  of the base  10  are formed in a single piece, e.g. by stamping a metal plate; however, the invention is not limited thereto. 
     Please refer to  FIG. 9 , which is a partially-exploded view of a keyswitch structure  3  of another embodiment according to the invention. The keyswitch structure  3  is substantially structurally similar to the keyswitch structure  1 , so the keyswitch structure  3  still uses the reference numbers of the keyswitch structure  1  in principle. For other descriptions about the keyswitch structure  3 , please refer to the relevant descriptions about the keyswitch structure  1 , which will not be repeated in addition. A difference between the keyswitch structure  3  and the keyswitch structure  1  is that the keyswitch structure  3  does not use the constrained vertical movement produced by the interaction between the vertical constraining structure  112 , the vertical guiding structure  114 , and the vertical guided structure  122 . The lift mechanism  14  of the keyswitch structure  3  includes two third supports  146  that are symmetrically disposed in the horizontal direction D 2  under two side edge portions of the keycap  12  respectively. Each third support  146  is connected to the base  10  and keycap  12  through connection portions  116  and  124  respectively. When the keycap  12  moves up and down relative to the base  10  in the vertical direction D 1  through the lift mechanism  14 , the first support  142  rotates about a first rotation axis  142   b  (indicated by a center line, equal to the sharp edge  1422   a ) relative to the base  10 . The second support  144  rotates about a rotation axis (equal to the sharp edge  1442   a ) parallel to the first rotation axis  142   b  relative to the base  10 . The third support  146  rotates about a second rotation axis  146   a  (indicated by a center line) relative to the base  10 . Therein, the first rotation axis  142   b  and the second rotation axis  146   a  are non-parallel, so the keycap  12  is constrained by a plane constructed by the first rotation axis  142   b  and the second rotation axis  146   a  and then can steadily move up and down. In the embodiment, the first rotation axis  142   b  is perpendicular to the second rotation axis  146   a , but the invention is not limited thereto. It is added that the first support  142  itself can constrain the movement of the keycap  12  on the first rotation axis  142   b , so in practice, the lift mechanism  14  of the keyswitch structure  3  can make the keycap  12  steadily move up and down by a proper disposition of the first support  142  and the third support  146  (e.g. in a disposition that the first support  142  and the third support  146  can support the keycap  12  in equilibrium). 
     In the above embodiments, the first side edge portion  1422  of the first support  142  abuts against the base  10  through the sharp edge  1422   a . The third side edge portion  1442  of the second support  144  abuts against the base  10  through the sharp edge  1442   a . Therein, the sharp edges  1422   a  and  1442   a  are disposed at the first side edge portion  1422  and the third side edge portion  1442 , but the invention is not limited thereto. Please refer to  FIG. 10  and  FIG. 11 .  FIG. 10  is an exploded view of a keyswitch structure  5  of another embodiment according to the invention.  FIG. 11  is a sectional view of the keyswitch structure  5 ; therein, the position of its cutting plane is indicated by the line X-X in  FIG. 3 . The keyswitch structure  5  is substantially structurally similar to the keyswitch structure  1 , so the keyswitch structure  5  still uses the reference numbers of the keyswitch structure  1  in principle. For other descriptions about the keyswitch structure  5 , please refer to the relevant descriptions about the keyswitch structure  1 , which will not be repeated in addition. A difference between the keyswitch structure  5  and the keyswitch structure  1  is that in the keyswitch structure  5 , the first side edge portion  1422  of the first support  142  abuts against a base  50  through a sharp edge  118 , and the third side edge portion  1442  of the second support  144  abuts against the base  50  through a sharp edge  120 . Therein, the sharp edges  118  and  120  are disposed on the base  50 . In the embodiment, the sharp edges  118  and  120  are formed by bending upward a portion of a bottom plate  102  of the base  50  (e.g. by a stamping process). In this case, the abutting plate  106  is unnecessary for the base  50 . Similarly, the keycap  12  of the keyswitch structure  5  can steadily move up and down relative to the base  50  through the first support  142  and the second support  144 . For other movement illustrations about the keyswitch structure  5 , please refer to the relevant descriptions about the keyswitch structure  1 , which will not be repeated in addition. It is added that in the embodiment, the sharp edges  118  and  120  respectively consist of three short edge segments. In practice, the sharp edges  118  and  120  can be realized by more, longer edge segments, even by a single edge. For each of the above examples, in logic the set of the plurality of edge segments can be regarded as the sharp edge of the invention. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.