Typewriting machines – Key-board or key lever-actuating mechanism – Key-cap or key-stem structure
Reexamination Certificate
2000-01-19
2001-02-06
Hilten, John S. (Department: 2854)
Typewriting machines
Key-board or key lever-actuating mechanism
Key-cap or key-stem structure
C400S491200, C200S344000
Reexamination Certificate
active
06183150
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a computer key, more particularly to a computer key that has a pair of pivotally connected linking frames disposed between a base plate and a push button, wherein the linking frames are retained positively on the base plate.
2. Description of the Related Art
U.S. Pat. No. 5,580,194 discloses a computer key including a one-piece base plate which is punched to form left and right retaining guideways that are spaced apart from each other in a longitudinal direction of the base plate. The retaining guideways include left and right retaining portions which extend uprightly from the base plate, and left and right blocking portions which extend from distal ends of the retaining portions away from each other and substantially longitudinal to the base plate. The blocking portions have left and right widths defined in a direction transverse to the longitudinal direction by front and rear left and right rough edges. A frame assembly includes first and second linking frames which are pivotally connected at intermediate portions thereof. Each of the first and second linking frames includes a transverse axle oriented in a transverse direction of the base plate, and having a middle segment of a length shorter than the width of the respective blocking portion and insertable slidably under the respective blocking portion, and front and rear segments which extend beyond the front and rear rough edges of the respective blocking portion. The first linking frame has a pair of first linking arms respectively and radially extending from the front and rear segments thereof. The second linking frame has a pair of second linking arms respectively and radially extending from the front and rear segments thereof. Each of the second linking arms includes a pin member extending outwardly and transversely from the intermediate portion thereof. Each of the first linking arms has an elongated slot formed longitudinally in the intermediate portion thereof for inserting the pin member of the respective one of the second linking arms therein such that the pin member is movable along the elongated slot. The intermediate portion of each of the first linking arms has a guiding groove disposed in an inner surface thereof proximate to the second linking arm that is pivotally connected thereto. The guiding groove extends downwardly from an upper surface in a direction transverse to the first linking arms and is communicated with the respective one of the elongated slots so as to guide insertion and slipping of the pin member into the respective one of the elongated slots from above.
After the first and second linking arms have been pivotally connected to each other, the transverse axle of the first linking frame is initially inserted under the right blocking portion. The transverse axle of the second linking frame is pulled by shifting the pin members in the elongated slots so as to permit the second transverse axle to slip over an upper surface of and be disposed under the left blocking portion in order to be slidable in the left retaining guideway. Since no positioning means is disposed in the slots to limit the movement of the pin members in the slots, the transverse axle of the second linking frame is liable to separate from the left retaining guideway when the transverse axles are moved away from one another. Therefore, the linking frames are liable to disengage from the base plate. In addition, the pin members are liable to escape from the slots via the guiding grooves, thus resulting in undesired separation of the first and second linking frames.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a computer key having linking frames that can be retained positively on a base plate.
Another object of the present invention is to provide a computer key in which the linking frames can be retained positively to one another.
According to the present invention, a computer key comprises a one-piece base plate, a membrane circuit, a flexible sheet member, an upright elastomeric biasing member, a first linking frame, a second linking frame, and a push button. The base plate includes left and right slidably retaining guideways which are spaced apart from each other in a longitudinal direction of the base plate to define an actuation area therebetween. The left and right slidably retaining guideways are respectively formed by punching the base plate so as to have left and right retaining portions which respectively extend uprightly from an upper surface of the base plate, and left and right blocking portions which extend respectively from distal ends of the left and right retaining portions away from each other and substantially longitudinal to the base plate so as to block movement in an upward and normal direction relative to a plane of the upper surface of the base plate. The left and right blocking portions have left and right widths defined in a transverse direction relative to the longitudinal direction of the base plate by front and rear left edges and front and rear right edges, respectively. The membrane circuit is disposed on the upper surface of the base plate, and has a contact area superimposed upon the actuation area, and first left and right openings which are disposed to match positions of the left and right blocking portions so as to permit extension of the left and right blocking portions outwardly of the first left and right openings. The sheet member is superimposed on the membrane circuit, and defines an actuation transmitting area and an annular mounting area which surrounds the actuation transmitting area. The actuation transmitting area is of a dimension matching that of and is superimposed on the contact area of the membrane circuit. The sheet member further has second left and right openings aligned with the first left and right openings to permit extension of the left and right blocking portions outwardly through the second left and right openings.
The biasing member is disposed on the mounting seat area of the sheet member, and includes an upper depressing portion and a spacing lower portion to space the upper depressing portion from the mounting seat area. The upper depressing portion is movable against a biasing action thereof to depress the actuation transmitting area as well as the contact area of the membrane circuit to generate an electrical signal.
The first linking frame includes a first transverse axle and a pair of first linking arms. The first transverse axle is oriented in the transverse direction of the base plate, and has a first middle segment of a first length shorter than the right width and insertable slidably under the right blocking portion, and first front and rear segments which flank the first middle segment and which extend beyond the front and rear edges of the right blocking portion respectively in the transverse direction. Each of the first front and rear segments has a cut-out first upper surface such that, while the first middle segment slides under the right blocking portion, the first upper surface will not contact either of the front and rear edges of the right blocking portion. The first linking arms extend respectively and radially from the first front and rear segments, and have a pair of first hooking fingers which are disposed at distal ends thereof and which are parallel to the first transverse axle.
The second linking frame includes a second transverse axle and a pair of second linking arms. The second transverse axle is oriented in the transverse direction of the base plate, and has a second middle segment of a second length shorter than the left width and insertable slidably under the left blocking portion, and second front and rear segments which flank the second middle segment and which extend beyond the front and rear edges of the left blocking portion respectively in the transverse direction. Each of the second front and rear segments has a cut-out second upper surface such that, while the second middle segment slides under the left blocking portion,
Baker & Botts L.L.P.
Hilten John S.
Nguyen Anthony H.
Peripheral Technology Inc.
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