Electricity: circuit makers and breakers – Electric switch details – Actuators
Reexamination Certificate
2003-02-28
2004-11-02
Friedhofer, Michael A. (Department: 2832)
Electricity: circuit makers and breakers
Electric switch details
Actuators
Reexamination Certificate
active
06812421
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a key switch device which performs a switching action while guiding a vertical movement of a key top by means of a pair of link members, a keyboard provided with the key switch device, and an electronic device provided with the keyboard. More particularly, the present invention relates to a key switch device which does not need a rubber spring generally used in a conventional key switch device and a complicated key top urging mechanism, and which can realize a key operation with a fine click touch in operating a key top and freely design the click touch, so that a constant depression characteristic of the key top can be maintained over a long term and furthermore the cost of the whole key switch device can be reduced, and a keyboard provided with the key switch device and an electronic device provided with the keyboard.
BACKGROUND ART
In association with the reduction in size, thickness, and others of a notebook-size personal computer which is one of electronic devices instruments, conventionally, there have been proposed various types of key switch devices to be used for a keyboard provided in the computer. This type of key switch device generally uses a rubber spring which urges a key top upward to hold the key top in a non-pressed position, whereas the rubber spring buckles with a click when the key top is pressed down, then performing a switching operation, and returns the key top to the non-pressed position after the switching operation.
The rubber spring is usually made of silicone rubber, EPDM rubber, etc., which is in general high in cost and the work of properly mounting the rubber spring while positioning in place in the key switch device. In the case where the rubber spring is used, the switching characteristic of the key switch device largely depend on the property of the rubber spring. It would therefore become difficult to freely change the switching characteristic of the key switch device.
In view of the above circumstances, many proposals to realize a key switch device without use of a rubber spring have been presented. For instance, Japanese patent unexamined publication No. 10-172380 discloses a key switch device in which a pair of first and second links are movably arranged between a hook of a key top and a hook of a base mold to guide the key top in a vertical direction, and a rubber sheet is stretched over between joint portions of the links.
In this key switch device, a circular projection formed on the underside of the key top is in close contact with the rubber sheet at the time of non-depression to hold the key top in a non-pressed state. When the key top is depressed, the key top presses the rubber sheet downward through the circular projection with increasing a tension of the rubber sheet so that the rubber sheet projects downward through a through hole, thereby switching, with a click, a switching area of a membrane sheet supported on a bottom plate. It is to be noted that, upon cancellation of the depression of the key top, the key top is moved upward by an elastic force of the rubber sheet to the original, non-pressed position.
The key switch device disclosed in the above-mentioned Japanese patent unexamined publication No. 10-172380, using no rubber spring, is not influenced by the size of a rubber spring and therefore can achieve an increase in designing freeness of the key switch device.
Although the above key switch device does not use a generally used rubber spring, however, the rubber sheet simply substitutes for the rubber spring and the rubber sheet is essential for the structure of the key switch device. It is therefore still insufficient in cost reduction of the whole key switch device. Furthermore, there is a problem that the work of stretching the rubber sheet over between the joints of the pair of links would complicate the work of assembling the key switch device. The key switch device also could perform a switching operation with a click touch when the key top is depressed; however, it is very difficult to freely design this click touch.
Furthermore, there has conventionally been proposed another key switch device configured so as to urge a key top upward through an elastic resinous member instead of the rubber spring and the rubber sheet. This elastic resinous member can be formed integrally with a resinous member constituting the key switch device and therefore it is effective in cost. If the key switch device is used for a long term, however, the elastic member may wear and a creep phenomenon may occur due to the stress repeatedly exerted on the elastic member, resulting in plastic deformation. When the elastic member wears and the plastic deformation occurs in the elastic member, the depression characteristic of the key top would be changed, deteriorating the key operability. When the wear and plastic deformation of the elastic member further advance, the elastic member could not elastically support any longer the vertical movement of the key top and, in some cases, the key switch device could not operate due to breakage or the like of the elastic member.
The present invention has been made to overcome the above problems and has an object to provide a key top device which can realize a key operation with a fine click touch during operation of a key top without needing a rubber spring generally used in a key switch device and a complicated key top urging mechanism, allow free design of the click touch, hold a constant depression characteristic of the key top over a long term, and achieve reduction in cost of the whole key switch device, and a key board provided with the key switch device and an electronic device provided with the keyboard.
DISCLOSURE OF INVENTION
(1) To achieve the purpose, the key switch device according to the first invention is a key switch device including a key top and a pair of a first and a second link members movably disposed under the key top, for performing switching of a switching section while guiding a vertical movement of the key top by the first and second link members, characterized by including: a first cam portion formed in the first link member; a second cam portion formed in the second link member and disposed facing the first cam portion; a cantilever member formed in a cantilever beam shape extending from the first link member or the second link member to support at least one of the first cam portion and the second cam portion; and an urging member for elastically urging the cantilever member in which one of the cam portions is formed in a direction to bring the first cam portion and the second cam portion into contact with each other.
The key switch device according to the first invention is characterized in that the first or second link member formed with the cantilever member is provided with a placing part for placing the urging member.
Furthermore, the key switch device according to the first invention is characterized in that the urging member is constructed of a torsion spring including a first arm which comes into contact with the cantilever member and a second arm facing the first arm, the placing part includes a first holding part for holding the first arm and a second holding part for holding the second arm.
The key switch device according to the first invention is characterized in that the first holding part movably holds the first arm and the second holding part fixedly holds the second arm.
In the key switch device according to the first invention having the above structure, one of the first cam portion of the first link member and the second cam portion of the second link member is supported by the cantilever member extending like a cantilever beam from the first or second link member and the urging member urges the cantilever member in the direction to bring the first and second cam portions into contact with each other. By the contact state of the first cam portion of the first link member and the second cam portion of the second link member and the cooperative operation of the urging member which urges the cantilever member,
Mochizuki Isao
Sato Hirofumi
Brother Kogyo Kabushiki Kaisha
Friedhofer Michael A.
Oliff & Berridg,e PLC
LandOfFree
Key switch device, keyboard with the key switch device, and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Key switch device, keyboard with the key switch device, and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Key switch device, keyboard with the key switch device, and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3288075