Electricity: circuit makers and breakers – Electric switch details – Actuators
Reexamination Certificate
2003-05-09
2004-03-16
Friedhofer, Michael A. (Department: 2832)
Electricity: circuit makers and breakers
Electric switch details
Actuators
Reexamination Certificate
active
06706985
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application takes priority from Korean Application No. 10-2002-0026724 filed May 15,2002.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a key switch for use in an input device such as a keyboard of a PC (Personal Computer), and more particularly to a key switch which is intended to realize a compact and slim keyboard and to enable a high keystroke rate and a resilient clicking sensation to a user via its simple configuration, thereby affording reliable key-input performance. The present invention also relates to a key switch, which is simplified in its construction so as to be produced by a simple manufacturing process.
2. Description of the Prior Art
These days, keyboard keys have been thinned and flattened to comply with needs for compact keyboards, and a high keystroke rate and a reliable and clear clicking sensation are required to enhance ease and reliability of a key-input operation. There are proposed various key switches for use in such keyboards.
For example, Japanese Patent Laid-Open No. 9-190735 discloses a key switch, described hereinafter.
In the key switch disclosed in the above Japanese Patent Laid-Open, a guide assembly for guiding an up-and-down motion of a keyboard key is comprised of first and second linking members. The first and second linking members are provided at lower facing ends thereof with teeth engaging with each other, and are connected at upper ends thereof to the top of key, to be slid along a lower surface thereof. Accordingly, when the key is pushed downward, the upper ends of the first and second linking members move far away from each other while sliding along the lower surface of the key. By this movement, the teeth of the first and second linking members are rotated while being engaged with each other. As the key is depressed, a resilient rubber actuator provided between the key and a base housing is pressed by the key, and the lowering actuator comes into contact to a contact of a membrane switch, thereby causing the key-input operation to be recognized. Upon release of the pushing force acting on the key, the pressed actuator is restored to its normal position while pushing the key upward, thereby allowing the key to be restored to its normal position.
The above-described key switch is advantageous in that the first and second linking members do not intersect in a “X” form, thereby affording simplification of the link guide assembly.
However, since the conventional key switch, as disclosed in the Japanese Patent Laid-Open, is equipped with a rubber actuator, the key switch inevitably becomes large.
Furthermore, since the key switch requires an additional rubber actuator, which is produced separately from the linking members, its manufacturing process is complicated.
In addition, since the key switch employs an actuator, which is configured to be simply pressed and to provide only a linear repulsion to the key, an acceptable clicking sensation cannot be achieved.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a key switch in which linking members of a linkage assembly are provided at connecting portions thereof with a connecting groove and protrusion, which serve as rotating shaft to simplify a structure of the linkage assembly, and in which the linkage assembly and means for restoring a keyboard key are integrally formed to achieve an acceptable clicking sensation and a compact key switch.
In order to accomplish the above object, the present invention provides a key switch comprising a keyboard key which is pressed down by a user's finger, a linkage assembly comprised of a first linking member with an arm connected to an outer end thereof, a second linking member with an arm connected to an outer end thereof, and a downwardly convex bow-shaped elastic object connected between the arms of the first and second linking members, which is lowered by pressure of the key to cause a key-input operation to be recognized and is raised together with the key by release of the pressure on the key, one of the first and second linking members including a coupling recess at its inner end and a hinge protrusion at its side surface, and the other of the first and second linking members including a coupling protrusion at its inner end and a hinge protrusion at its side surface, the coupling recess and protrusion being engaged with each other to constitute a linkage rotating shaft, a frame including hinge hooks engaged with the hinge protrusions of the first and second linking members, and an FPC (Flexible Printed Circuit) placed on the frame, which enables a key-input operation to be recognized via contact with the linkage assembly, wherein, as the key is pressed down, the arms of the first and second linking members are rotated downward around the linkage rotating shaft while the linkage rotating shaft is raised, and the elastic object is gradually flattened and then bent into an upwardly convex bow shape, thereby providing a clicking sensation to a user and a restoring force to the linkage assembly.
The keyboard key may be provided at its lower surface with ribs, each of which include an elongated linkage guide hole and a support cut, and each of the first and second linking members may be provided at its outer end with a key-positioning protrusion and a support knob, each key-positioning protrusion being slid along a link guide hole when the key is depressed, the support knob continuously supporting the key from the time when the key is positioned at its uppermost level.
The elastic object may be provided at its lower surface with a contact protrusion to reliably push a contact portion of the flexible printed circuit.
The key switch may further include a linkage bar disposed under the key to support the key and to evenly distribute pushing force acting on the key, wherein a rotating axis of the linkage bar is positioned to have an angle of 90° with respect to a rotating axis of the linkage assembly, so that the linkage bar does not interfere with the linkage assembly.
REFERENCES:
patent: 6100482 (2000-08-01), Koma et al.
patent: 6118092 (2000-09-01), Hayashi
patent: 6300583 (2001-10-01), Hsu
patent: 6444933 (2002-09-01), Chun
patent: 6534736 (2003-03-01), Lee et al.
patent: 6586695 (2003-07-01), Sato et al.
patent: 9190735 (1997-07-01), None
Friedhofer Michael A.
Green, Winner and Sullivan, P.C.
SMK Korea Co., Ltd.
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