Waterproof automotive detector switch integrates resistors

25-09-2015 | Alps | Design Applications

A growing number of vehicle models in today’s automobile market are equipped with idle stop (start–stop) systems that help to improve fuel efficiency. For safety reasons, the automatic engine restart function of an idle stop system is suspended while doors are opened and closed. Sometimes, however, when there is a technical fault such as a broken circuit, the idle stop system will not activate. To bring out a vehicle’s full fuel efficiency potential, a mechanism is required to both accurately detect open or closed status and quickly detect breaks, shorts or other abnormalities in surrounding circuits.

Detection typically employs an open/closed detection switch combined with a resistor (or resistors). Circuit breaks or shorts are detected from abnormal output voltage values during on–off switching. Earlier switches have primarily used external lead-type resistors that are soldered to the open/closed detection circuit, but issues remained, such as the occurrence of soldering defects and faulty water resistance sealing.

The SPVQD Series from ALPS contributes to quality consistency and circuit downsizing by incorporating chip-type resistors actually inside the switch package while retaining the same dimensions (15.2mm × 6.4mm × 7.45mm) as the existing SPVQA Series. This also allows the user to omit processes for affixing external resistors. As up to three resistors can be mounted, facilitating a wide range of resistance settings, the product also helps to improve design freedom.

Furthermore, the detector employs a 'clip' type double-sided sliding contact structure that clamps a fixed contact from both sides. This was achieved through application of ALPS proprietary precision processing technology. The configuration enables high contact reliability with strong particulate, vibration and impact resistance. The dust and water resistance rating of the SPVQD Series is IP67, says the company.

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