Design: Pad Sensitivity

Whilst testing the assembly of the devices I encountered a problem with responsiveness on the pads.

The current construction of the upper layer of the device is as such –

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The pad sits within the faceplate and has a layer of around 2mm underneath of soft silicone. It’s worth noting here that if this underlayer covered the whole of the faceplate,this issue wouldn’t exist. Unfortunately due to the pads being cut from a larger grid of pads (due to the failed casting of my own pads), I’ve had to cut away most of the excess. This means that when the faceplate is fitted into the enclosure, any pressure on the faceplate will cause this underlayer to protrude into the hole, causing no contact with the force sensor.

 

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I knew that in order to solve this Id have to create more space between the faceplate and the sensor. Exactly how much is determined by this underlayer of silicon (around 1.5mm). 3D printing allowed me to quickly print a 1.5mm spacer to fit under the faceplate. This adds another layer of the ‘sandwich’ which counteracts the issue with the button pad itself.

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A quick test with this spacer shows that I now have a responsive button pad with adequate spacing for each layer.

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And the ‘sandwiched’ upper layer with working pad –

 

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