Telephonic communications – Supervisory or control line signaling – Substation originated
Reexamination Certificate
1998-09-28
2001-03-27
Chiang, Jack (Department: 2642)
Telephonic communications
Supervisory or control line signaling
Substation originated
C379S433020
Reexamination Certificate
active
06208730
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an attachment structure of a key top used in a small-sized electronic equipment such as an inter-call receiver, or the like, and particularly relates to a key top attachment structure in which the structure of the key top is simple and the key top can be easily attached to a casing and held stably.
One or more switches are provided in a small-sized electronic equipment such as an inter-call receiver, or the like. A key top which is good and stable in manipulability of the switches and which is low in manufacturing cost has been desired.
Examples of conventional key tops include: a key top which has a stopper and which is pressed into a casing having a lock portion in which the stopper of the key top is locked; and another key top which has an elastic stopper and which is inserted into a casing while the stopper is being bent. A further key top is disclosed in JP-U-6-79042, which is provided with an arm having spring property for suppressing looseness and clattering between the key top and a casing.
Of the conventional key tops, the key top having a stopper pressed into a casing needs high-precision parts in order that the key top can be assembled while it is difficult to be taken off. If there are large variation in dimension of the parts, there is a problem that the key top or the casing is damaged or deformed at the time of assembling, or the key top is detached from the casing in use.
On the other hand, as for the key top which has an elastic stopper and which is inserted into the casing while the stopper is being bent, the key top is inevitably increased in size so as to obtain proper bending property of the stopper. Thus, there is a problem that a large space is required for installation of the key top.
On the other hand, the operation of the key top becomes heavier if there is provided a spring for eliminating looseness between the key top and the casing in order to prevent abnormal sound from being generated by vibrations caused by a calling vibrator or speaker singing in an intercall receiver. If a spring with a light load is used to make the key top operation lighter, a larger space is required. If such a spring is provided, the spring cannot be formed through resin molding integrally with the casing, and the spring has to be manufactured as a separate part. Accordingly, the number of parts increases, and the structure becomes complicated.
SUMMARY OF THE INVENTION
The present invention is intended to solve the foregoing conventional problems, and it is an object thereof to provide a key top attachment structure in which a key top can be attached to a casing without press-inserting a stopper into the casing, and in which the stopper and the casing are free from permanent deformation.
Another object of the present invention is to prevent abnormal sound or looseness from being produced by vibrations caused by a calling vibrator or speaker singing, with a simple structure and without making the operation of the key top heavier.
A further object of the present invention is to minimize a space required for attachment of the key top, and make it possible to assemble the key top easily from the outside of the casing.
According to the present invention, in order to solve the foregoing problems, the key top attachment structure is designed such that a casing includes a spring and a lock portion, and a key top includes a protrusion for pushing down the spring when the key top is attached to the casing from the outside of the casing, and a stopper locked in the lock portion for preventing the key top from being taken off from the outside of the casing. The key top is held by the spring and the lock portion.
With such a configuration that the key top is attached while the spring of the casing is being bent, the key top and the casing is free from permanent deformation, and the assembling work can be made easily. In addition, parts do not require so high precision in dimension. After attachment, the stopper of the key top is locked in the lock portion of the casing so that the spring prevents the key top from being taken off from the outside. Since the spring molded integrally with the casing abuts against the key top in the vicinity of the fulcrum of the key top, looseness can be eliminated with a simple structure and without making the operation of the key top heavier, and a required space can be minimized.
According to a first aspect of the present invention, a key top attachment structure for attaching a key top to a casing of a small-sized electronic equipment is arranged as follows: The casing includes a spring and a lock portion. The key top includes a protrusion for pushing down the spring when the key top is attached from the outside of the casing, and a stopper locked in the lock portion so that the key top cannot be taken off from the outside of the casing. The key top is held by the spring and the lock portion. Accordingly, there is an effect that it is possible to attach the key top to a casing without pressing the stopper, so that the stopper and the casing are not deformed permanently.
According to a second aspect of the present invention, the key top attachment structure according to first aspect is arranged such that the spring presses the key top, and the stopper abuts against the lock portion, whereby looseness between the casing and the key top is suppressed by an elastic force of the spring. There is an effect that the key top is held stably by means of the spring so that abnormal sound or looseness is prevented.
According to a third aspect of the present invention, the key top attachment structure according to the first aspect is arranged such that the spring presses the key top in the vicinity of a fulcrum of the key top to thereby make an operating force of the key top smaller than a reaction force of the spring. There is an effect that the key operation is made lighter even if a spring with a large reaction force is used.
According to a fourth aspect of the present invention, the key top attachment structure according to the first aspect is arranged such that the spring is provided with a hole, while a gradient for improving mold releasability at the time of resin molding is given to an outer circumference of the spring, and the casing and the spring are formed by integral molding. There is an effect that the structure is simplified so that the number of parts is reduced, and the strength is enhanced so that deformation at the time of resin molding can be prevented.
According to a fifth aspect of the present invention, the key top attachment structure according to the first aspect is arranged such that the protrusion is inserted through a hole formed in the spring, so that the position of the key top is restricted. There is an effect that the movement of the key top is restricted by the hole.
According to a sixth aspect of the present invention, a key top attachment structure for attaching a key top to a casing of a small-sized electronic equipment having a circuit board with a switch mounted thereon is provided. The casing includes a spring of a cantilever structure with a rectangular hole, a pair of first and second lock portions provided on opposite sides of the spring, and a third lock portion partially covering the rectangular hole on a fixed end side of the spring. The key top includes a pressure reception surface adapted to be pressed by a finger, first and second stoppers opposite from the pressure reception surface, a protrusion portion constituted by a third stopper, a first protrusion, and a second protrusion, and a third protrusion. The second protrusion temporarily abuts against the spring. The protrusion portion is inserted through the rectangular hole, so that the first, second and third stoppers are made to abut against the first, second and third lock portions correspondingly. The third protrusion is made to abut against a head of the spring. The first protrusion is made to face the switch provided under the rectangular hole so as to push down the switch. There is an effect that
Ikeda Kazuhiro
Nishikawa Kenichi
Sugawara Shuuichi
Chiang Jack
Matsushita Electric - Industrial Co., Ltd.
Pearne & Gordon LLP
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