JPS6160526B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a lid plate having a plurality of openings, each of which allows a key plunger to pass therethrough, and an internal contact comprising a plurality of recesses in the area of the openings of said lid plate. a push-button switch comprising a plate, through each of said recesses one actuating pin of a key plunger protrudes on each actuation, and said key plunger is arranged through each of said recesses on a bottom side of said contact plate; The present invention relates to a push button switch which is movable so as to be electrically connected to one contact spring assembly.

One such push-button switch is known, for example, from German Patent No. 924,934. In this German patent, two laterally projecting legs are arranged on the push button body, the lower edges of the legs serving as a fulcrum for the push button body. Therefore, the push button body performs a pivoting movement when actuated. Therefore, as the actuating pin, which is integrally formed in the pushbutton body, is moved along a circular path, the recess in the contact plate, which is designed as a flat plate, moves out of line (moves diagonally). It must be designed with an appropriate size to avoid this. The pushbutton head used with this pushbutton switch tapers upwardly into a conical shape, thus
When the switch is actuated, a relatively large gap is created between the pushbutton head and the limiting edge of the opening in the cover plate. Therefore, dirt and other small particles pass through this gap and then through the recess in the cover plate into the confines of the contact spring assembly.

The object of the invention is inter alia to design a pushbutton key of the above type which prevents the ingress of dust. Such a configuration, for example, is intended to provide a long service life for the keyboard and keypad.

According to the invention, the above object is achieved by arranging an upwardly projecting collar around each recess, said sleeve-like part of the key plunger being able to be actuated in a direction perpendicular to the plane of the contact plate. surrounded by the key plunger in all positions occupied by the key plunger, and by designing both the collar and the sleeve-like portion to be of sufficient length to enable actuation of the key plunger upon overtravel. Ru. Due to this design of the pushbutton switch, dirt only collects on the surface of the contact wafer and cannot penetrate into the contact spring assembly.

However, it is already known from DE-A-2615902 for explosion-proof pushbutton switches to provide both the pushbutton key and the key guide with mutually telescoping parts. In this case, the radial gap has an axial spacing of up to 3 W (W being the width of the gap as described by VDE 0171).
However, over time, this narrow gap can become filled with dust or abrasive debris from the guide member, preventing actuation of the pushbutton key or preventing the pushbutton key from returning to its normal position. It will be prevented. however,
According to the present invention, the above-mentioned problem can be avoided because the key plunger can be operated in overtravel.

Further advantageous embodiments of the invention are described in the dependent claims.

Hereinafter, the present invention will be described with reference to embodiments shown in the accompanying drawings.

Reference numeral 1 indicates a cover plate. A contact plate (wafer) 2 is inserted into the lid plate 1 from below. Contact plate 2
is suitably provided with a peripheral rim portion 3. The peripheral rim part 3 can be inserted with minimal play into the downwardly projecting wall part 4 of the cover plate 1.

The cover plate 1 is provided with an opening 5. Through the opening 5 protrudes a key plunger 6 which can be displaced perpendicularly to the plane of the contact plate 2, the head 7 of the key plunger 6 or the push button knob 8 arranged on the head 7 being directed upwards. It is being
The outer dimensions of either the head 7 or the push-button knob 8 are suitably dimensioned to permit only very small backlash with respect to the inner edge of the opening 5. With this configuration, it is possible to almost prevent dust from entering the inner space.

The contact plate 2 is provided with a recess 9 below each opening 5 . According to the invention, each recess 9 is surrounded by an upwardly projecting collar 10. This collar 10 is surrounded by a sleeve-like part 11 of the key plunger 6. Preferably, there is a slight play between the collar 10 and the sleeve-like part 11. The sleeve-like part 11 is provided with a cylindrical recess 12 . Inside the recess 12,
The upper part of the return spring 13 is arranged as a compression spring. The lower end of the return spring 13 is in contact with the contact plate 2.

The upward travel of the key plunger 6 is limited by a transverse arm 14 formed integrally with the key plunger and cooperating with an inner edge 15 formed in the lid plate 1. The arm 14 can also serve as a detent device together with the guide member 16 of the lid plate 1.

The key plunger 6 is provided with an actuating pin 17 that projects through the recess 9. This actuating pin 17 is connected to the contact spring assembly 1 located on the bottom side of the contact plate 2.
It is possible to press one of the flat springs 8 and 19. The lengths of both the collar 10 and the sleeve-like member 11 are such that the collar 10 and the sleeve-like member 11 are engaged with each other throughout the entire stroke of the key plunger 6, yet when the key plunger 6 overtravels, i.e.
The key plunger 6 is dimensioned to allow the key plunger 6 to be depressed further down than the travel required to actuate the contact spring assemblies 18,19.

Due to the collar 10 and the sleeve-like member 11 and due to the close contact between the outer surface of the push button knob 8 and the opening 5 of the cover plate 1, dirt cannot reach the contact spring assembly 18, 19 through the recess 9. It is guaranteed that this can be reliably prevented. In addition, the close contact between the outer surface of the peripheral rim portion 3 of the contact plate 2 and the inner surface of the wall member 4 of the cover plate 1 further prevents dust from entering. By making the length of the key plunger 6 suitable, overtravel is possible, so at the same time, the key plunger 6
Friction between the head 7 or the push button knob 8 and the inner edge of the cover plate 1 and/or friction between the collar 10 and the sleeve-like member 11 and/or the collar 10
Any deposits resulting from friction between the return spring 13 and the walls of the cylindrical recess 12 around the contact spring assembly 1
It is possible to prevent any harmful effect on the operation of the key plunger 6 acting on the keys 8 and 19.

[Brief explanation of the drawing]

The accompanying drawings illustrate one embodiment of a push button switch according to the present invention. 1... Lid plate, 2... Contact plate, 3... Rim part,
4... Wall member, 5... Opening, 6... Key plunger, 7... Head, 8... Push button knob, 9...
... recess, 10 ... collar, 11 ... sleeve-like member, 12 ... recess, 13 ... spring, 14 ... arm, 15 ... inner edge, 16 ... guide member, 17 ...
...Actuation pin.

Claims (1)

[Scope of Claims] 1. A plate 2 having a plurality of openings 9 through which the actuating pin 17 of the key plunger 6 passes, contacts 18 and 19 of the switch are arranged below the openings 9, and each opening 9 brim 10 that protrudes upward around the
is arranged, and the collar 10 is always surrounded by a sleeve-like member 11 of the key plunger 6, which actuates vertically against the plane of the plate 2 against the force of the spring 13. In a push button switch in which the length of the collar 10 and the length of the sleeve-like member 11 are determined so that the plunger 6 can be operated with overtravel, the plate 2 itself It is a contact plate on which contacts 18 and 19 are mounted, and the contact plate 2 is covered with a cover plate 1 having a plurality of openings 5 corresponding to the openings 9 of the contact plate 2, and the keep plunger 6 The outer peripheral wall of the head 7 or the outer peripheral wall of the push button knob 8 placed on the key plunger is connected to the opening 5 of the cover plate 1.
in slidable alignment with the inner surface of the contact plate 2, said contact plate 2 comprising a rim member 3 projecting above its periphery, said rim member being substantially free of bumps within the wall member 4 of said lid plate 1. a push-button switch which can be inserted in a state in which the key plunger 6 further comprises a transverse arm 14 adapted to cooperate with a guide member 16 of the cover plate 1; 2. In the push button switch according to claim 1, the sleeve-like member 11 serves as a support for the return spring 13 brought into contact between the sleeve-like member 11 and the contact plate 2. A push button switch featuring 3. The push button switch according to claim 1 or 2, wherein the sleeve-like member 11 includes a cylindrical recess 12 that is engaged with a portion of the return spring 13. A push button switch. 4. In the push button switch according to any one of claims 1 to 3,
A push-button switch, characterized in that said arm 14 forms, together with the inner edge 15 of said cover plate 1, a device for limiting the stroke of said key plunger 6.