Low-Mounting Force Keyswitch

The present invention relates to a keyswitch, and more particularly to a low-depression force keyswitch for facilitating quick assembly.

Keyboards are common input devices for data processing equipment. A keyboard is configured with a plurality of keyswitches. Conventionally, keyswitches are manually assembled to an array of openings. In light of this, production speed can only be increased with low-mounting-force keyswitches. Furthermore, durability of each keyswitch is critical for proper data input. As a result, an ideal keyswitch is easily mounted to the base frame, while removed therefrom is difficult.

Referring to FIGS. 1 and 2, a keycap 40, stoppers 70, and keycap flanges 46 provide a sliding area. The stopper 70 is a thin, rectangular plate. Slides 52, 62 of the sliding members 50, 60 are movably received within the sliding area. The positions of the slides 52, 62 vary as the sliding members 50, 60 move. FIG. 1 shows the positions of the slides 52, 62 before the keycap 40 is assembled thereto. FIG. 2 shows the positions of the slides 52, 62 after the keycap 40 is removed therefrom.

The assembly/removal force for the keycap 40 depends on the length of the slides 52, 62 within the stoppers 70. Accordingly, when a span between the stoppers 70 is fixed (length B shown in FIG. 1), selecting a suitable total length of the slides 52, 62 becomes a difficult issue. If the length is too long, the keycap becomes difficult to assemble. However, if the length is too short, the keycap will be easily removed from a base frame. Additionally, the assembly/removal force and removal force can also be affected by clearance which varies during a molding process.

Taiwan Utility Patents 80206310, 83204123, 84214256, 85202834, and U.S. Pat. Nos. 5,463,195, 5,504,283, 5,512,719 disclose pertinent techniques. However, the problem mentioned above is still unsolved.

An objective of this invention is to provide a keyswitch having a keycap defining a plurality of sliding slots in which corresponding linkages of slides are movably assembled thereby providing a low-assembly force and a high removal force.

In order to achieve the objective set forth, a keyswitch for use with a keyboard comprises a base forming at least a pair of mounting sockets. A first sliding member is movably assembled to one of the mounting sockets. The first sliding member is formed with a slide at a free end thereof. A second sliding member is movably assembled to another of the mounting sockets. The second sliding member is formed with a slide at a free end thereof. Hinging means is arranged between the first and second sliding members and defines at least a sliding groove in on one of the first and second traversal rods, and forms a bud on another of the first and second traversal rods corresponding to the sliding groove. A keycap defines a depressing face and a peripheral flange extending from edges of the depressing face. At least a pair of sliding slots are defined in corners of the depressing face for movably receiving slides of the first and second sliding members.

These and additional objects, features, and advantages of the present invention will become apparent after reading the following detailed description of the preferred embodiment of the invention taken in conjunction with the appended drawings.

FIG. 1 is a top view of a conventional keyswitch in which a keycap is assembled;

FIG. 2 is a top view of FIG. 1 in which the keycap is removed;

FIG. 3 is a perspective view of a keycap in accordance with the present invention;

FIG. 4 is a top view of a keyswitch in accordance with the present invention when a keycap is assembled;

FIG. 5 is a top view of FIG. 4 when the keycap is removed;

FIG. 6 is an exploded view of a keyswitch in accordance with the present invention;

FIG. 7 is a side elevational view of FIG. 4; and

FIG. 8 is a partial assembled view of FIG. 4.

Referring to FIG. 6, a keyswitch 99 in accordance with the present invention comprises a base 11, a first slide 20, a second slide 30, and a keycap 40. The base 11 is a rectangular plate forming a mounting socket 12 at both sides. Each socket 12 is configured by a pair of retaining posts 121. The base 11 further forms guiding portions 14 on central portions of opposite sides thereof. Each guiding portion 14 is provided with a guiding slot 141. The first sliding member 20 has a U-shaped configuration including a pair of traversal rods 24 connected by a pivotable portion 22 which is pivotably received within the socket 12. Each rod 24 is further provided with a sliding groove 26 on an inner side thereof. Each groove 26 is provided with a suitable curved portion. A first slide 28 is formed on a free end of each rod 24.

The second sliding member 30 has the same configuration as the first sliding member 20 and includes a pair of traversal rods 34 connected by a pivotable portion 32 which is movably received within another socket 12. Each traversal rod 34 is formed with a bud 36 for movably engaging with the sliding groove 26 of the first sliding member 20. Each rod 34 further includes a second slide 38 at a free end thereof. A reinforced rib 35 is bridged between the rods 34 to increase the rigidity of the second slide 30.

Referring to FIG. 3, the keycap 40 defines a depressing face 48 for receiving a depressing force. The keycap 40 forms a pair of guiding posts 44 on opposite sides thereof and defines a U-shaped sliding slot 42 in each corner. The U-shaped sliding slot 42 is defined by a horizontal plate 421 and a vertical plate 422 both having a trapezoidal shape. By the provision of the trapezoidal horizontal plate 421, a trapezoidal space T (marked with a dotted line) is defined between opposite sliding slots 42. The trapezoidal space T features a wide bottom Tb and a narrow top Tt. The vertical plate 422 is connected with the keycap 48. Each U-shaped sliding slot 42 defines an entrance 420 for receiving the first and second slides 28, 38 of the corresponding first and second sliding members 20, 30 as seen in FIG. 7. By this arrangement, when the keycap 40 is depressed, not only will the bud 36 of the second sliding member 30 move along the sliding groove 26 of the first sliding member 20, but the first and second slides 28, 38 will also move horizontally along the U-shaped sliding slots 42 of the keycap 40. When the keycap 40 reaches the highest point (start of removal force), the first and second slides 28, 38 are located at the widest position 423 of the horizontal plate 421 of the U-shape sliding slot 42, as shown in FIG. 5. At this stage, it has the longest engaging length which benefits the strongest anti-removal force. When the keycap 40 reaches the lowest position (FIG. 4), the slides 28, 38 are located at the narrowest position 424 of the horizontal plate 421 featuring the lowest assembly force.

FIG. 8 shows the sliding members 20, 30 are assembled to the socket 12 of base 11. The keycap 48 is partially cut off for clearly description.

While the present invention has been described with reference to a specific embodiment, the description is illustrative of the invention and is not to be construed as limiting the invention. Various modifications to the present invention can be made to the preferred embodiment by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.