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'[OT]: Re: Need some switch ideas'
2001\04\05@112749 by Steve Nordhauser

picon face
Steve,
I've got the image.  It would certainly work for equalizing the pressure.
I think it would even be feasible for the shutter button.  It would be
a problem for all the menu switches that would need to penetrate the
body (the internal boards would need to look like swiss cheese).

On the other hand, I would like to visit a consultant in New Zealand.....
Steve
--
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Imaging Systems
IEM Corp.
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Albany, NY 12202-1924
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Subject:
       Re: [OT] Re: Need some switch ideas
  Date:
       Thu, 5 Apr 2001 09:50:50 +1200
  From:
       Steve Baldwin <.....steveKILLspamspam@spam@TLA.CO.NZ>



> As someone suggested, if the back of the actuator
> isn't sealed, there is no pressure differential.  Unfortunately, that
> means that sand could get under the button head and jam the switch.
> So, they solve most of the power issues, but not the pressure issue
> unless I am missing something. Steve

Here's another approach.
If you take the constant pressure inside the enclosure out of the
equation, the problem goes away. What you have at the moment is
a rod with 1 atmosphere on one end and a varying pressure (1-6
atm) on the other. If you can apply the external pressure to the
other end of the rod, the two will cancel each other out so the key
pressure will remain constant, regardless of depth.

My ascii art sucks so I'll try a description to illustrate.

Take one waterproof box and drill a largish hole that goes right
through both sides. Stick a rubber patch over both holes. Measure
between the inside faces of the rubber sheet an cut a piece of solid
rod to match. When assembled, pressing one rubber patch will
make the other deflect outwards. When submerged, the pressure
deflection on both ends is the same so the rod doesn't move and
the box is still sealed.
Now put a cross piece on the bar so that it looks like a letter "t"
and position the cross piece above the switch on the circuit board.
Make one of the outside rubber patches inaccessable to fingers
with a (unsealed) cover of some sort and you have a push button
that has the same actuation pressure at any depth.

Obviously as described there are some practical limitations. You
can apply the same basic concept using pivots, etc to make it fit
within your mechanical constraints. Assuming you are moulding
your own case, the extra plastic costs almost nothing and you get
the constant switch pressure you require.

PS. I've been looking for a business related reason to travel to
North America/Canada and try some ice diving. You obviously need
to hire a consultant on this one. :-)

Steve.



======================================================
Steve Baldwin                Electronic Product Design
TLA Microsystems Ltd         Microcontroller Specialists
PO Box 15-680, New Lynn      http://www.tla.co.nz
Auckland, New Zealand        ph  +64 9 820-2221
email: stevebspamKILLspamtla.co.nz      fax +64 9 820-1929
======================================================

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2001\04\05@114150 by Alan B. Pearce

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>On the other hand, I would like to visit a consultant in New Zealand.....

There is some good diving in NZ, especially around the North of the North
Island, but then I guess you already knew that :)

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2001\04\05@172155 by steve

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face
Steve,

> I've got the image.  It would certainly work for equalizing the
> pressure. I think it would even be feasible for the shutter button.
> It would be a problem for all the menu switches that would need to
> penetrate the body (the internal boards would need to look like swiss
> cheese).

That was more for illustrating the concept. Picture a "V" shaped
piece of plastic behind a rubber keypad. The "V" pivots on the apex
and one end is below the button and the other is in the gap
between the buttons, the "V" only needs to be a few mm high.

> On the other hand, I would like to visit a consultant in New
> Zealand.....

I had two US customers "visit" last month. I guess you guys can't
be good at navigation. It always seems to take them a couple of
weeks and a lot of miles to find their way back to the airport.
And I have had business meetings at the Poor Knights Islands with
the dress standard being a wetsuit.

Steve.


======================================================
Steve Baldwin                Electronic Product Design
TLA Microsystems Ltd         Microcontroller Specialists
PO Box 15-680, New Lynn      http://www.tla.co.nz
Auckland, New Zealand        ph  +64 9 820-2221
email: stevebspamspam_OUTtla.co.nz      fax +64 9 820-1929
======================================================

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2001\04\05@181312 by rottosen

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face
Here in Denver, at the foot of the Rocky Mountains, the standard visit
is timed to end early on Friday. This leaves time to get to the ski
slopes for weekend skiing.


-- Rich


Steve Baldwin wrote:
{Quote hidden}

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