DE8804316U1 - Coding switch - Google Patents

Description

U.Z. 589.26

Helmut Hechinger

Junkersstrasse 4

7730 VS-Schwenningen

CODING SWITCH

The invention relates to a coding switch, in particular for clocks, counters and the like, according to the preamble of claim 1.

Such coding switches are often integrated into the circuit board of electric clocks with electronic chimes. Since this circuit board is usually not sealed dust-tight, the conductor tracks can easily become dirty, which can lead to short circuits and thus to false signals.

The invention is therefore based on the object of creating a coding switch in which: with simple means and without hermetic encapsulation, contamination of the

Conductor tracks and the associated risk of short circuits are largely excluded.

This object is achieved according to the invention in a coding switch of the type mentioned at the outset by the characterizing features of claim 1.

These measures ensure that the electrically conductive segments are essentially at the same height as the insulating material between them, which reduces the abrasion of the sliding contact and improves contact. The conductive elastic material of the sliding contact causes continuous self-cleaning of the conductive segments of the conductor tracks, which largely prevents incorrect contacts and switching errors and significantly increases the service life of the coding switch.

Advantageous embodiments of the invention are described in the subclaims.

This coding switch is also equally suitable for other position indicators such as roller counters and the like.

An embodiment of the invention is explained in more detail with reference to the figures. It shows:

Fig. 1 is a plan view of a segment arrangement of the conductor tracks of a paper holder according to the invention,

Fig. 2 shows a section through a coding switch according to the invention, in which in particular the sliding contact and its mechanical fastening and guidance can be seen.

Pig. Jl a perspective view of a holding disk with support ribs carrying the sliding contact, and

Fig. 4 is an enlarged section along the line A-B in Fig. 1.

As can best be seen from Fig. 1 and 2, the coding switch according to the invention consists of a circuit board 10, which can also be integrated into the general circuit board of an electric clock, and on which four conductor tracks 12 are arranged in a concentric ring shape. The conductor tracks 12 are divided into conductive segments 14 and non-conductive segments 16 according to a pattern characteristic of the desired coding. A receiving pin 18 is inserted into a central hole in the circuit board 10, which carries a receiving disk 20, to which a radially extending sliding contact 22 is attached in such a way that it scans the four conductor tracks 12 when the receiving disk 20 is rotated. Two support ribs 24 arranged on the receiving disk 20, each offset by 120° in relation to the sliding contact 22, ensure that the receiving disk 20 runs exactly parallel to the circuit board 10. A compression spring 28 is inserted between the outer surface of the receiving disk 20 and a spring plate 26 provided at the outer end of the receiving pin 18, which causes a uniform pressure of the sliding contact 22 against the conductive segments 14 of the conductor tracks 12.

The sliding contact 22 consists of an electrically conductive elastic material, preferably of "contact rubber", a mixture of silicone rubber and carbon. The conductor tracks 12 consist of copper, and the conductive segments 14 are copper-plated onto the corresponding sections of the same. The spaces between the conductive segments

The conductive segments 14 are filled with an insulating material, preferably with resist 30, in such a way that the surfaces of the conductive segments 14 do not protrude or only protrude slightly above the resist surface, the elevation of the conductive segments 14 in relation to the resist surface advantageously being 0 - 100 μm. In a preferred embodiment of the invention, the surfaces of the conductive segments 14 are gold-plated with a thin layer of approximately 0.1 μm.

For the operation of the coding switch according to the invention, the receiving pin 18 is connected, for example, to the hour tube of an electric clock, so that the receiving disk with the sliding contact 22 sweeps over the entire surface of the ring-shaped conductor tracks 12 with its conductive segments 14 once within twelve hours and thereby controls the correct beat sequence of the hourly strike. Since the conductive segments 14 form an almost smooth surface with the resist surface 30, the scanning movement of the sliding contact 22 only produces extremely little abrasion. In addition, the elastic material of the sliding contact 22 causes a continuous self-cleaning of the conductive segments 14. In this way, incorrect contacts and the switching errors caused by them are largely avoided, and the service life of the coding switch is significantly increased.

110

Claims (1)

PROTECTION CLAIMS Coding switch, in particular for clocks, counters and the like, wherein a number of concentric conductor tracks arranged in a ring are provided on a circuit board, which are divided into conductive and non-conductive segments in a pattern characteristic of the desired coding, and over which a sliding contact driven, for example, by the hour pipe of an electronic clock is guided in a scanning manner, characterized in that the scanning sliding contact (22) extends radially over all conductor tracks (12) and consists of an electrically conductive elastic material, that the conductive segments (14) are applied to concentric continuous conductor tracks (12), and that the spaces between all conductive segments (14) are filled with stop varnish (30) in such a way that the surfaces of the conductive segments (14) do not protrude or only protrude slightly above the stop varnish surface. Coding switch according to claim 1, characterized in that the electrically conductive elastic material of the sliding contact (22) consists of a mixture of silicone rubber and carbon. Postal cheque account: KaMerun*&Tgr;&bgr;9,79-7&xgr;4 · ,BHnkkenti): Q4ut«ehe Bank AQ Vllllngen (BU 69470039) 146332 3. Coding switch according to claim 1 or 2, characterized in that the surfaces of the conductive segments (14) have an elevation of 0 - 100 μπα in relation to the resist surface. 4. Coding switch according to one of the preceding claims, characterized in that the conductor tracks (12) consist of copper, and that the conductive segments (14) are copper-plated onto the conductor tracks (12). 5. Coding switch according to one of the preceding claims, characterized in that cUe conductive segments (14) are gold-plated with a thin layer of approximately 0.1 μηη.