Dual shot!

Have you ever wondered how digital cameras do focus/shutter functions with the same button? probably not*, but I did.

Of course, dismantling a fully functioning camera was out of the question. First, because they are so integrated, that they’re prone to be broken once open, and second, and most importantly, because sometimes, breaking open microswitches, involves actually damaging them beyond use.

Luckily, today I was poking around on my trash-not-to-throw-away bin, and found a flexy circuit from a camera I didn’t remember taking apart…

123a - Camera switchfe

If you remember (13), normal smd switches, have a flat bendy disc to make the actual contact. (in fact, those bendy discs have tons of aplications beyond integrated switches, I might cover them someday).

So, what’s inside?

123b - Camera switchfe

Uh? That’s not a simple bendy disc, isn’t it? Welcome to the compound disc-ring land!

Let’s go deeper:

123c - Camera switchfe

A-ha!

On the first half of the button travel, the ring makes contact with the two semicircular contacts, then, as it lays flat against them, the only option avaliable is for the smaller disc to actually bend like a normal switch does, closing the three contacts together.

It is indeed a very interesting design, and I’ll probably use it someday, as you can buy them over Ebay at about 2 to 3$ each. Not cheap, but if you have space constraints, this is one of the ways to go.
(Btw, the switch measures 6*6mm)

*Seriously, you should start having a more inquisitive mind, electronics is not only resistors, capacitors, coils and transistors, you know…

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