Electronic apparatus including keyboard with key switch device

Details Electronic apparatus including keyboard with key switch device Electronic apparatus including keyboard with key switch device

2002-09-17

2003-07-01

Scott, J. R. (Department: 2832)

Electricity: circuit makers and breakers

Electric switch details

Actuators

C200S0050EA, C200S517000, C361S679090, C361S689000

Reexamination Certificate

active

06586695

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to a key switch device in which a key top is vertically guided by a pair of link members to perform a switching operation, a keyboard provided with the key switch device, and an electronic apparatus provided with the key switch device. The invention relates more particularly to a key switch device in which a key top, when pulled up, is removed together with a pair of link members, thereby facilitating reassembling and maintenance of the key switch device, a keyboard provided with the key switch device, and an electronic apparatus provided with the key switch device.
2. Description of Related Art
Conventionally, various types of key switch devices for a keyboard have been proposed with the trend toward more compact and thinner notebook-size personal computers, which belong to an electronic apparatus. For example, Japanese Laid-Open Patent Publication No. 9-190735 discloses a key switch device in which a key top is vertically guided by first and second links.
In the disclosed key switch device, rotating shanks formed at upper ends of arms, which constitute the first link, are rotatably supported by bearing portions of the key top, and a sliding shank, formed between the arms, is slidably supported by slide guides of a housing. Also, rotating shanks formed at upper ends of arms, which constitute the second link, are rotatably supported by bearing portions of the key top, and a sliding shank formed between the arms is slidably supported by slide guides of the housing.
In a key switch device, an outer wall of an engagement member of a key top is interposed between a pinch shaft and an upper shaft of a first link member, while an outer wall of an engagement member of the key top is interposed between a pinch shaft and an upper shaft of a second link member. When the key top is pulled up, the pinch shaft and the upper shaft of the first link member cooperate with each other to pinch the outer wall of the engagement member, and the pinch shaft and the upper shaft of the second link member cooperate with each other to pinch the outer wall of the engagement member. Thus, when the key top is pulled up, the key top is removed together with the first and second link members, thereby facilitate reassembling and maintenance of the key switch device.
In such a key switch device, the key top is vertically guided by the first and second links so that the key top vertically moves while maintaining a horizontal state regardless of which part of the key top is pressed.
As shown in FIG. 14 of Japanese Laid-Open Patent publication No. 9-190735, each bearing portion in which each rotating shank of the first and second links is rotatably supported has an entrance upwardly tapered off and an inverted U-shaped recess continued from the entrance.
Each rotating shank of the first and second links is readily supported by the bearing portion shaped as described above. Each rotating shank is guided by the tapered entrance and snapped into the inverted U-shaped recess.
SUMMARY OF THE INVENTION
The key top sometimes needs to be removed to perform maintenance or the like. In the above-described conventional key switch device, the rotating shanks of the first and second links are supported by the bearing portions by the elastic force of the bearing portions, which is just great enough to permit the rotating shanks to be snapped in. Thus, in many cases, the holding force of the slide guides that hold the first and second links becomes greater than the holding force of the bearing portions that hold the rotating shanks.
As a result, when removal of the key top is attempted, only the key top may be detached leaving the first and second links at the housing. If this happens, because the first and second links are not interconnected, the first and second links separate.
If the first and second links separate, it is extremely difficult to reassemble the key top to the first and second links because the first and second links are very small parts and hard to handle. In some cases, the key switch device cannot be reassembled.
The invention addresses the forgoing problems and provides a key switch device in which a key top, when pulled up, is removed together with a pair of link members, thereby facilitating reassembling and maintenance of the key switch device, a keyboard provided with the key switch device, and an electronic apparatus provided with the key switch device.
According to a first aspect of the invention, a key switch device includes a key top; a guide member disposed below the key top for supporting the key top to guide vertical movement of the key top, the guide member having a first link member provided with a first upper shaft and a first lower shaft and a second link member provided with a second upper shaft and a second lower shaft; and a lower engagement member disposed far below the key top and next to the guide member, the lower engagement portion having a first lower engagement portion in which the first lower shaft is slidably engaged and a second lower engagement portion in which the second lower shaft is slidably engaged; a first upper engagement member that links the first upper shaft to the key top such that the first upper shaft is pivotally engaged in the first upper engagement member; a second upper engagement member that links the second upper shaft to the key top such that the second upper shaft is pivotally engaged in the second upper engagement member; and a switching portion that performs a switching operation in accordance with the vertical movement of the key top. The key switch device further includes a first pinch portion provided in the first link member such that part of the first upper engagement member is interposed between the first pinch portion and the first upper shaft; and a second pinch portion provided in the second link member such that part of the second upper engagement member is interposed between the second pinch portion and the second upper shaft, wherein the parts of the first and second upper engagement members are pinched therebetween when the key top is pulled up.
In the key switch device structured as described above, the first link member is provided with the first pinch portion such that a part of the first upper engagement member is interposed between the first pinch portion and the first upper shaft, which is pivotally engaged in the first upper engagement member on the underside of the key top. Likewise, the second link member is provided with the second pinch portion such that a part of the second upper engagement member is interposed between the second pinch portion and the second upper shaft, which is pivotally engaged in the second upper engagement member. When the key top is pulled up to perform maintenance of the key switch device, the pulling-up force is exerted such that the first pinch portion cooperates with the first upper shaft to pinch therebetween the part of the first upper engagement member, and that the second pinch portion cooperates with the second upper shaft to pinch therebetween the part of the second upper engagement member. The holding force for the key top generated between the upper shafts of the first and second link members and the first and second upper engagement members becomes greater than the holding force for the engagement member generated between the lower shafts of the first and second link members and the first and second lower engagement portions of the engagement member.
Thus, when the key top is pulled up, the key top is not removed leaving the first and second link members at the engagement member. The key top is always removed together with the first and second link members, thereby facilitating maintenance and reassembly of the key switch device.
According to a second aspect of the invention, an electronic apparatus includes a keyboard provided with a key switch device for entering data including characters, symbols, and others, a display that displays thereon the characters, symbols, and others, and a control unit that controls the display

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