DE8915139U1 - Bistable switch device for an alarm clock - Google Patents

Description

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Braun Aktiengesellschaft

- 3 - O5448-PT4/He/nl

19.12.1989

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The present invention relates to a bistable switching device which is suitable for a push-button switch-operated electronic alarm clock. The bistable switching device consists of a push-button formed in a housing shell, by the successive actuation of which, against the action of a powder device, a displaceable actuating element connected to the push-button is brought into the positions of both tables one after the other with the aid of a sliding surface control arrangement.

Bistable switching devices of this type are known, for example, from DE-OS 27 17 252 and DE-GH 82 00 201, whereby in the second document a switching device was proposed which only requires a single control disk attached to an actuating element connected to a push button. By means of a corresponding sequence of two different tooth sequences formed alternately on the control disk, the actuating element can be brought into the two stable positions with the aid of two stationary pawls by rotating the control disk.

The actuating element is also pre-tensioned by a spring, against whose action the push button is pressed down. This separately provided spring, which in the embodiment shown in this document is designed like a hairpin spring, must be attached to the actuating element and also held to the housing shell of the respective device. The separate design and attachment makes the manufacturing process more complicated and expensive on the one hand. On the other hand

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Even if the spring is intact, the entire arrangement will be inoperable if, for example , the retaining projections specially designed for the spring in the housing shell break or the spring jumps out of a fault. Another element that increases costs and is mechanically critical is the rotating control disk.

The invention is therefore based on the object of specifying, based on the features in the preamble of patent claim 1, a stable switching device which can be implemented with as few individual parts as possible and at the same time ensures reliable function.

This object is achieved according to the invention in that the spring device consists of a spring arm element integrated into the push button and that the sliding surface control arrangement is designed as an arrangement of control curves fixed in the housing shell. The switching device according to the invention primarily includes a simplified manufacturing process, since on the one hand the integration of a spring arm element into the push button eliminates the complex attachment of a spring that has to be manufactured separately and the formation of mounting devices for this. On the other hand, the production is made easier by using the fixed

I. Arrangement of control cam elements simplified, In addition, the

The operating time of the switch is increased by these simplifying and element-saving measures.

The use of a fixed control cam arrangement also enables, in comparison to the alternating tooth sequence of a control disk, more precise specifications of different switching paths when switching into the two stable positions. For example,

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- 5 - 0S448-PT4/He/nl

19.12.1989

In an alarm clock, the switching path from the ON to the OFF position can be made short and vice versa. It can be made longer to any desired extent.

The use of the integrated spring arm element also opens up further possibilities and advantages. The two-arm design, which can be easily implemented, ensures that the firing device is subjected to low loads in both stable positions - which correspond to the ON and OFF positions of a function. A higher restoring force or load only occurs briefly when switching from OFF to ON. If the spring arms and push button are made of plastic, for example, undesirable relaxation processes in this material are avoided in this way.

By using two molded, curved spring arms, which in the combined and separated positions each produce different elastic moduli for the entire spring element, it is also possible, for example, to switch a function on or off relatively easily.

In both solutions regarding the attachment of the fixed control cam arrangement opposite the actuating element, only a single simple locking element is required for a reliable switching process.

In the following, the invention is explained in more detail using an embodiment shown in the drawings. They show:

Fig. IA the schematic representation of an embodiment of the bistable switching device according to the invention in its off position, from the interior

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6 - 05448-PT4/He/nl

19.12.1989

the alarm clock viewed from the inside of the push button and the actuating element,

Fig. 1 B Switching on process according to the switch device according to Fig. 1 A,

Fig. 1 C Switching position after the switching process Fig. 1 B and

Fig. 2: Longitudinal section through the switching device in the stable switch-on position shown in Fig. IC according to section line I-I.

In figures 1A to 1C a bistable switching device according to the invention is shown in its two stable positions, ie in an OFF and an ON position, as well as in an intermediate position which occurs in the switching sequence from OFF to ON indicated by the arrow Z. The switching device comprises an arcuate push button 1 which has a width and thickness suitable for manual actuation. An actuating element 2 which is also arcuate and of a smaller width and thickness is formed on the push button 1.

Furthermore, according to Figs. 1 A to 1 C, spring arms 3a, 3b are formed on the two lateral ends of the push button 1, which are connected to the actuating element 2, the outer surfaces 11 of which end with the push button end surfaces 12. In addition, an elongated, vertically extending locking element 6 is formed in the middle of the switching device on the push button 1 and on the actuating element 2 connected to it. To guide this integrated unit consisting of push button 1, spring arms 3a, 3b and actuating element 2,

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Braue UttongeMNechaft

- 7 - 05448-PT4/He/na

19.12.1969

For connecting the actuating member 2 with the locking element 6, two guide sections 2a, 2b are provided, which are formed in one piece with the actuating member 2 and are rounded and extend downwards, each with an elongated hole 13a and 13b. A pin 9 engages in each of the elongated holes 13a and 13b and is provided on the inside of an upwardly open key guide body 10 (Fig. 2) with a rectangular cross-section. The key guide body 10 comprises side pins 8 (Fig. 1 A to 1 C) which laterally limit and guide the unit guided therein, i.e. the push button ends or the spring arm sections 3a, 3b connected to them.

The spring arms 3a, 3b, which extend downwards from the push button 1 according to Figs. 1 and 2 and are bent inwards, have a rectangular cross-section and are wider in their upper part, which is adjacent to the side surfaces 8, for better guidance and narrower in their lower area to achieve sufficient elasticity. In their lower area, they have a width less than half that of the push button 1, for example. In a unit made of plastic, consisting of the push button 1 and spring arms 3a, 3b, suitable elasticity values are obtained with a spring arm thickness of, for example, 1 to 2 mn.

The spring arms 3a, 3b also have reinforced sections 4a, 4b at their free ends, which extend upwards into the interior of the switching device and which have opposite, enlarged contact end surfaces 14, 15 for the arms 3a, 3b. In the area of these sections 4a, 4b, the spring arms 3a, 3b slide over a sliding surface 5, which is part of a rib 16 formed in the key guide body 10.

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In the ready position 10 of the free end of the locking element 6, according to figures 1A to 1C, a fixed cam control arrangement 7 is also provided on the inside of the key guide body 10. This consists of an arrangement of two raised cam elements 17, 18 formed on this inside, the first of which is open at the top and the second, closed at the top, cam element 18 lies between the open, parallel guide legs 19 of the first element 17. Both cam elements 17, 18 are U-shaped, with the second element 18 being arranged with its base leg 22 parallel to a guide leg 19 of the first element 17 and its two guide legs 23 pointing diagonally downwards. A curved projection 24 projects from the first element 17 into the opening 21 formed by the second element 18, parallel to the two legs 23 of the second element 18.

The rod-shaped locking element 6 according to Fig. 2, which is rounded at the bottom and is attached to the underside of the push button 1 and is let into a corresponding recess in the actuation device 2 formed thereon and is stabilized there _; has an engagement pin 6a at its lower free end, which is also angled. The engagement pin 6a, which is directed from the locking element 6 towards the wall 8 carrying the control cam element 17, 18 and is approximately aligned with the push button element end surface 25 guided thereon, runs through the path 20 formed by the control cam elements 17, 18 described above.

Before the switching process is explained in detail below, it should be noted that a switching cam (not shown) can be positioned at a largely arbitrary location on the actuating element 2 (or possibly also on a provided locking element 6).

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designed 1st, which also has a switch not shown for

actuated according to the unstable position assumed by the switching device. §

If the switching device is in the position shown in Fig. IC ON position, i.e., push button 1 is in its '

upper position, in which it is limited at the top by the pins 9, the two spring arms 3a, 3b are separated from each other by a few millimeters, for example, and only apply the preload required to maintain this push button position. In this ON position, the engagement pin 6a is located outside the cam control arrangement 7.

If the push button 1 and thus the elements 2, 3 and 6 integrated therein are now actuated, the spring arms are subjected to only a little more tension than in the ON position, since the distance between the spring arm sections 4a, 4b is first overcome before they touch each other. The engagement pin 6a, which is located essentially above the middle of the cam control arrangement 7 before actuation, first slides over the outer surface of the upper, obliquely arranged, first U-shaped element 23 and, after it has traveled the relatively short distance between the cam projection 24 of the first element 17 and this leg 23 of the second element 18, engages in the upper, rounded bend of the first element 18 (Fig. 1A). The return of the locking element 6 to its central position (Figs. 1 and 2) is achieved by the fact that when the locking element 6 is forced into the cam control arrangement 7, it is bent resiliently to the left or right about its clamping points X.

In this OFF position (FIG. IA) the pins 9 are located approximately in the middle of the guide cable 13a, 13b of the guide rails.

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Braun Aktiengesellschaft

- 10 - O5448-PT4/He/nl

19.12.1989

sections 2a, 2b of the actuating element 2. The spring arms 3a, 3b are therefore only slightly less tensioned than in the switched-on position, so that permanent deformations of the plastic material do not occur in either stable position. The switching process from ON (Fig. 1C) to OFF (Fig. 1k ) is also easy to carry out because only small spring forces have to be overcome. In addition, the switching path from ON to OFF specified by the control cam arrangement 7 is completely short, and the switching process takes place quickly. The OFF position can be quickly detected both visually and by touch, because the side surfaces 8 of the key guide body 10 are bevelled at the top to match the curve of the push button in such a way that the side surfaces 8 form a homogeneous surface with the push button in this position.

If the push button is now pressed again to switch on the switching device, the spring arms 3a, 3b are briefly pressed together more strongly, as can be clearly seen in Fig. 1 B, whereby the locking element 6 completely bypasses the base 26 of the first element 17 and the lower leg 23 of the second U-shaped element 18 of the curve control arrangement 7. In the intermediate position shown in FIG. IB, i.e. at the reversal point of the locking element 6 at

the tip of this lower leg 423£, the spring tension is greatest and the pins 9 simultaneously abut the top of the elongated holes 13a, 13b.

The device is therefore switched on with more force than it is switched off due to the short-term spring overtension. The arrangement and design of the cam control arrangement 7 is also selected so that the entire switching-on path to be covered by the locking element 6a (from the position 1n of flap 1A to the position of flap 1B) is longer than the switching-off path (from flap 1A to the position of flap 1B).

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IC up to Fig. IA) 1st. In contrast to easy switching off with a short switching off path, switching on with a longer switching on path requires greater effort.

In the example shown, a stationary cam arrangement 7 is traversed by a moving locking element 6, 6a. However, the reverse case of a control cam arrangement integrated in the actuating element 1, which is traversed by a stationary locking pin arranged in the guide body, is also possible.

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Claims (5)

Braun AkUengesetohoft 05448-PT4/He/na 19.12.1989 Claims 1. Bistable switching device for an alarm clock, with an in a housing shell with a push button that can be moved ^ whose successive &?M% igung against the effect of a f Spring device means a spring connected to the push button, sliding actuation^! led with the help of a GIeHfI surface 'x control arrangement is brought one after the other into the two stable positions, I' characterized by that the spring device consists of a spring arm element (?a, 3b) integrated into the push button (1) and that the sliding surface control arrangement (7) is designed as an arrangement of control curves fixed in the housing shell (10). 2. Switching device according to claim 1,
characterized, that the spring arm element consists of two curved spring arms (3a, 3b) formed on the push button (1), the upper ends (4a, 4b) of which are displaceable over a sliding surface (5) ) only touch in one of the two stable positions. 3. Switching device according to claim 2,
characterized, that the fixed control cam arrangement (7) is stationary relative to the moving actuating member (2) and is passed through by a locking element (6) which engages in this one position and is provided on the push button (1). 4. Switching device according to claim 2, characterized, that the fixed control cam arrangement (7) on the moving fixed BBRUft Braun AktiengaMfieohaff - 2 - O5448-PT4/He/nl 19.12.1989 t1gungsg11ed (2) is provided and is passed through by a stationary locking element (6) which is locked in this stable position. 5. Switching device according to one of the preceding claims,
characterized,
that the path traversed by the locking element (6), i.e. from entry into the control cam arrangement (7) to locking in this one stable position, is shorter than the path traversed when leaving this position until exiting the control cam arrangement into the other stable position.