On Jan 24, 2008, at 5:04 PM, John Daynes wrote:
> I'm working on a medical device that provides critical therapy to a
> patient.
> We have a keypad that is used to control the device, and on the
> keypad is a
> power button. We are sensitive to accidental actuations of the power
> button,
> which would turn the device off, potentially terminating therapy. We
> implemented a three-second delay on the button to avoid accidentally
> turning
> the device off, but the delay is seen as a real annoyance by users.
> I'm
> looking for suggestions (hopefully research-based) on how long the
> delay
> should be to prevent accidental actuation without causing undue
> operator
> annoyance.
1. Why does the power button have to be on the keypad where it can
easily be hit by accident?
2. If the delay is seen as an annoyance by the users, what do *they*
say it should be? (Not that they will be correct, but maybe they can
guide to no delay, 1/2 second, 2 seconds, etc.)
3. Users are used to a press-and-hold mechanism for powering on/off a
cell phone. What is the standard delay there, and why not use it?
4. Can the key be locked or protected to avoid accidental hits? Make
it a slider, add a flip-down cover on it, place it in the least likely
place to be accidentally hit.
5. Make powering down be a "secret move", something less likely to
happen by accident. Not that it has to be "up up up right B left B B
down A", but just "two presses in 1/2 second" might suffice. (If the
button is labelled so that doesn't have to be memorized, of course.)
-- Jim Drew
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