Electricity: magnetically operated switches – magnets – and electr – Permanent magnet-actuated switches
Reexamination Certificate
1998-11-20
2001-05-08
Donovan, Lincoln (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Permanent magnet-actuated switches
Reexamination Certificate
active
06229420
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a proximity switch having a housing, a sensor element, e.g. a pot core with a sensor coil, and a printed circuit board which is embedded in a potting compound in the housing and is electrically connected at one end to the pot core and, at the other end, to connection pins.
BACKGROUND INFORMATION
German Patent No. 92 00 772 describes a conventional proximity switch. Here, the sleeve-shaped housing is provided with a number of bores at the level of a centrally arranged light-emitting diode, in order to make it possible to see the switching state of the proximity switch from all sides. A transparent connector insert extending up to in front of the bores serves as an optical waveguide from the light-emitting diode in the direction of the bores. The connector insert is securely connected to connection pins whose ends are electrically connected directly to the printed circuit board, after having been bent. The connector pins with bent ends can be soldered directly onto the printed circuit board.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a proximity switch which can be assembled without transmission of forces to the pot core via the printed circuit board. In addition, it is an object of the present invention to specify an appropriate production process.
The object is achieved by the fact that the connection pins, apart from the potting compound, are held only by a direct mechanical connection to the printed circuit board, and that a connector insert integrated in the housing surrounds the connection pins without performing a supporting function for them.
An advantageous exemplary embodiment is obtained if the printed circuit board is produced together with the connection pins and the sensor element as a modular switch insert which, apart from the potting compound, is supported in the housing only using the sensor element. This exemplary embodiment proves to be particularly undemanding to assemble, since the switch insert can easily be produced in advance and its use as a module is then made much easier.
Furthermore, it is advantageous if the connector insert has guide means which are used to guide the solder pins during assembly. This technical measure also simplifies assembly. Expediently, the guide means are produced as lugs with bores having a bore diameter which is greater than the thickness of the connection pins.
If the switch insert is embedded in a potting compound in the housing which is produced by potting the housing only once, this reduces the complexity of assembly and at the same time the cost as well.
In order to make it possible to use a light-emitting diode in order to indicate the switching status through an aperture provided in the housing, the connector insert comprises, at least in part, transparent material.
In addition, it is advantageous if the connector insert has a circumferential seal which seals off any gap to the housing in such a manner that it prevents potting compound from escaping through apertures for indicating status.
Another object, of providing a production process for a proximity switch, is achieved by the following process steps:
A cylindrical housing, whose one end opening is covered by a cap, is potted with potting compound to such an extent that a defined interspace remains open between an aperture in the housing, which aperture serves to indicate the switching status, a switch insert assembled as a module from a printed circuit board, connection pins and a sensor element, e.g. a pot core with a sensor coil, is introduced into the uncured potting compound, which displaces some of the potting compound toward the aperture, a connector insert which is partially open at its base is inserted into the housing and displaces potting compound, this potting compound at least partially filling the interspace between the connector insert and the interior wall of the housing.
The process is advantageously improved if, after it has been introduced into the uncured potting compound, the switch insert is supported on the cap, by its own weight only, using the sensor element. This means that no other forces, which may possibly be destructive, act on the sensor element, e.g. the pot core.
REFERENCES:
patent: 5498651 (1996-03-01), Collins
patent: 5508611 (1996-04-01), Schroeder et al.
patent: 5789920 (1998-08-01), Gass
patent: 5803604 (1998-09-01), Pompei
patent: 5878824 (1999-03-01), Mercer et al.
patent: 92 00 772 (1992-04-01), None
patent: 93 02 714 (1993-05-01), None
patent: 93/15554 (1993-08-01), None
Bäuml Alfred
Gassner Robert
Schmitt Manfred
Donovan Lincoln
Kenyon & Kenyon
Siemens Aktiengesellschaft
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