GB2335080A

GB2335080A - Pushbutton arrangement

Info

Publication number: GB2335080A
Application number: GB9904417A
Authority: GB
Inventors: Dierk Schmidt; Juergen Luginsland; Joerg Stierle; Peter Wolf; Gunter Flinspach
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-03-06
Filing date: 1999-02-25
Publication date: 1999-09-08
Anticipated expiration: 2019-02-25
Also published as: FR2775829A1; CH694414A5; FR2775829B1; GB9904417D0; GB2335080B; DE19809684A1

Abstract

A pushbutton arrangement, particularly for a distance measuring device, comprises a flexible switching mat 20 having a plurality of contact-bearing switching domes 14, 18, 19 for contacting mating contacts on a printed-circuit board 21. At least two switching domes 18a,18b are combined into a multi-stroke switch 18 having switching regions which are separate from one another.

Description

,' - 1, 2335080 1 Pushbutton arrangemen The invention proceeds from a

pushbutton arrangement according to the preamble of claim 1. A pushbutton arrangement is already known, which comprises a flexible switching mat having a plurality of contact-bearing switching domes for contacting mating contacts on a printed-circUlit board. Said switching mat is formed in such a way that the switching domes are held constantly in an initial position remote from the printed- circuit board and only contact the printedcircuit board upon pressure operation optionally via a button connected to the switching dome. The known pushbutton arrangements have the drawback that, when pressure is exerted upon a switching dome in a specific operating direction, only one switching function may be realized. A defined stroke has to be completed before the switch is operated.

Furthermore, there are also pressure-operated switches which are designed as rocker switches. In the case of said switches, a tilting component in various tilting directions is superimposed on the necessary stroke so that, depending on the tilting direction, different switching positions arise.

Me pushbutton arrangement according to the invention having the features of claim 1 has the advantage that in one operating direction of a switching dome (stroke direction) a plurality of switching positions may be realized. Particularly in the case of use 'm a distance measuring device, this has the advantage that it is possible with the switching mat also to realize switches which comprise a first switching position for locating an object to be measured, e.g. by means of a laser beam, and a second switching position for initiating the actual measuring process. While simultaneously utilizing the advantages of switching mats, such as their ease of manufacture and extreme water tightness, it is possible in said manner to achieve a high level of user friendliness when measuring with distance measuring equipment.

2 Advantageous developments and improvements of the pushbutton arrangement according to the invention are possible by virtue of the measures indicated in the dependent claims.

An embodiment of the invention is illustrated 'm the drawings and s described in detail below.

Figure 1 shows an exploded view of a distance measuring device provided with a pushbutton arrangement according to the invention; Figure 2 a longitudinal section through the distance measuring device; and Figure 3 a cutout from Figure 2 to an enlarged scale.

In Figure 1, a distance measuring device is denoted by the reference number 10. An upper housing shell 11 of the distance measuring device 10 is provided with various window-like openings 12. A substantially rectangular opening 12a is used for penetration of a display 13. Two oval openings 12b are used in each case for penetration of a control button 14. A further oval opening 12c is provided for a corresponding pushbutton 15 and a plurality of openings 12d are used for penetration of a keypad 16. The control buttons 14 take the form of switching domes 14' of a switching mat 20. The buttons 15, 16 are installed as cap-shaped inserts into the upper housing shell 11 and connected to further switching domes 18, 19 of a switching mat 20. The switching domes 14', 18, 19 on their underside carry contacts which, upon pressure operation, contact mating contacts on a printed-circuit board 21 and initiate the associated switching functions.

In Figure 2, the distance measuring device 10 is shown in longitudinal section. The upper housing shell 11 penetrated by the display 13, the control buttons 14, the button 15 and the keypad 16 may be seen. The upper housing shell 11 together with a lower housing shell 17 forms a complete housing for the distance measuring device 10.

3 Situated below the display 13 and the buttons 14, 15, 16 Mi the housing part 11 is the printed-circuit board 2 1, on which the mating contacts are surface-mounted at the side directed towards the buttons 14, 15, 16. Situated in between is the switching mat 20 with the switching domes 14', 18, 19 formed thereon.

The switching mat 20 substantially takes the form of a sheet having the raised portions which form the switching domes 14', 18, 19. The switching mat 20 is clamped by its edge 22 surrounding the switching domes 14', 18, 19 between a circumferential web 23, which projects inwards from the housing part 11, and the printed-circuit board 2 1. In said manner, the interior of the housing part 11 is sealed off to prevent moisture from penetrating through gaps between the buttons 14, 15, 16 and the upper housing shell 11.

The switching domes 14, 18, 19 are each connected to the switching mat 20 by annular webs 24. The annular webs 24 each have a thin-walled cross section which yields Mi the event of pressure upon the corresponding button 14, 15, 16. When a specific pressure is exceeded, the respective annular web 24 loses its dimensional stability and the underside of the buttons 14, 15, 16 comes into contact with the printed-circulit board 2 1. Provided at the underside of the switching domes 18, 19 are contactforming conductive particles, which connect the mating contacts on the printed-circw"t board 21 and hence initiate a specific switching function.

The distance measuring device 10 illustrated in the embodiment is provided with an injection laser diode 30, which produces a laser beam which is emitted along a longitudial axis 31 'm the direction of an arrow 32. Said laser beam is used to locate the object to be measured. Emission of the laser beam is initiated by means of the button 15 via the switching dome 18. Said switching dome 18 is designed as a double-stroke switch, having a first switching dome 18a 4 and a second switching dome 18b. The first switching dome 18a is annular and accommodates the second switching dome 18b partially inside it.

The first switching dome 18a is connected by an annular web 24a to the switching mat 20, which has a greater compliance than a second annular web 24b between first switching dome 18a and second switching dome 18b. For said reason, in the event of pressure upon the button 15, the first switching dome 18a will contact the printed-circuit board 21 first and, only in the event of increased pressure, will a corresponding contact with the second switching dome 18b arise. The switching region, in which the central switching dome 18b contacts the printed-circuit board 2 1, is separate from the annular switching region of the switching dome 18a in order to be able to control two different switching functions.

In the case of the present application of a distance measuring device, the double switching function of the double-stroke switch 18 has the advantage that in the first switching position a bearing beam, which is directed towards an object to be measured, may first be initiated. Once the desired object has been sighted, it is possible by increasing the pressure upon the button 15 to execute the second switching function, which is linked to an initiation of the measuring process. Usually, the measurement is effected using an echo time measuring method. In the case of a laser distance measuring device, the laser beam itself is used to determine the distance. In the case of an ultrasonic measuring device, in the second stroke position of the double-stroke switch 18 an ultrasonic signal is emitted.

In Figure 3, the button 15 with the switching dome 18 is shown to an enlarged scale compared to Figure 2. The switching dome 18 is integrally connected by the annular web 24a to the switching mat 20. The first switching dome 18a is in turn connected by the stiffer annular web 24b to the second switching dome 18b. The switching dome 18b is seated by a top part in a receiver 33 of the button 15. Because of the outward-acting initial tension of the switching dome 18, the button 15 is pressed by an annular collar 34 against the inner wall of the housing part 11.

The invention is not limited to the illustrated embodiment. It is, for example, conceivable to design -the switching dome 18 not merely as a double stroke switch but also as a multi-stroke switch, in which case flirther switching domes may be attached by annular webs.

6

Claims

1. Pushbutton arrangement, particularly for a distance measuring device (10), comprising a flexible switching mat (20) having a plurality of contact bearing switching domes (14', 18a, 18b, 19) for contacting mating contacts on a printed-circuit board (2 1), characterized in that at least two switching domes ( 18 a, 18b) are combined into a multi-stroke switch (18) having switching regions which are separate from one another.

2.

Pushbutton arrangement according to claim 1, characterized in that at least one of the switching domes (18a) is of an annular design and accommodates a central switching dome (18b) inside it.

3. Pushbutton arrangement according to claim 2, characterized in that the annular switching dome (1 8a) is connected by a first compliant web (24a) to the switching mat (20) and via a second compliant web (24b) carries the central switching dome (18b).

4. Pushbutton arrangement according to claim 3, characterized in that the first compliant web (24a) has a greater compliance than the second compliant web (24b).

5. Pushbutton arrangement according to claim 3) or 4, characterized in that the compliant webs (24a, b) are formed by annular surfaces in the shape of an envelope of a cone.

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6. Pushbutton arrangement according to one of the preceding claims, characterized 'm that the multi-stroke switch (18) takes the form of a double-stroke switch.

7. Pushbutton arrangement according to claim 6, characterized in that the first switching position of the double-stroke switch (18) is used to initiate a bearing beam and the second switching position is used to initiate a measuring process.

8. A pushbutton arrangement substantially as herein described with reference to the accompanying drawings.