h a l f b a k e r yA riddle wrapped in a mystery inside a rich, flaky crust
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A lot of devices and products and technical gear have
LED
indicators. Sometimes these are static — on for
something, off for lack of something. Sometimes they
blink to indicate “activity”. The way they blink is an
inversion of the ‘on’ logic, so that the light is on to
indicate that the function
is active or available or
working,
and to overload that single LED with another layer of
information, it is momentarily turned off in a brief flash
of
nothingness, and back on. Thus, you have devices that
will
have a single LED or rows of single LEDs (eg, one LED per
channel), each of which is either off (not working), on
(sitting there doing nothing) or blinking (actually doing
its
job).
It’s a subtle design point, but I feel that taking the LED
all
the way off before returning back to fully on is a bit
harsh
on the eyes and the attention. I think it’s
environmentally
noisy. I propose that UI designers take the brightness
down
to an intermediate level instead of off. This might be
halfway, in terms of power drive to the LED, or it might
prove to be something like 90% of full power (or maybe
the other way round — 90% reduced power) because of
the
non-linear way that human perception works. Or maybe
a
perceptual halfway isn’t as nice looking as taking it
down
by two thirds, or a third, or 72% apparent brightness, or
something.
Technicalogically, this would be slightly unsimpler than
simply having a single LED on a single pin of a port of a
processor (unless you drive it as PWM). However, if
you’ve
got two pins on the port to spare for one LED, you could
easily do it using the second pin to pull down the drive
current via a transistor, or using the second pin to add
drive current using resistor summing, or a variety of
different ways.
It would look nicer, and that’s the main thing.
[link]
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Seems reasonable, and I've seen 'multi-tone' LCD screens with varying shades of grey on-screen at the same time, so it's perfectly doable. |
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What would be nice in some applications would be a smooth-transition from on to off, by invoking a kind of ASDR envelope to each LCD-cell's -on- event - that way, you'd be able to construct a single chip with a common interface to control this type of display. |
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[EDIT] later - just realised my mix-up between LED and LCD. Much of the same stuff should apply though, shouldn't it? I think I've seen Christmas Tree lights that show a range of brightnesses, and Apply have that pulsing thing that tells you whether your laptop is on standby or not. |
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I'm sure I've seen flashing LED units in the past (some years ago) which have some circuit in them - you just feed in DC and they flash - so, some passive analogue circuit embedded inside. So it should be possible to have something capacitive in there to smooth the sharp edges from your binary drive - i.e.you don't have to use more processor pins or make fancy driver code. And you wouldn't even increase your power consumption hardly. |
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For sure, if the LED is gently pulsating, that would say to me "working", wheras when they are FLASHING ON OFF ON OFF I usually think "oh no - what's the problem ?" |
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Personally, I hate how everything simply must have an LED indicator nowadays, especially one that indicates that the unit is in 'standby mode.' LEDs may be power-efficient, but their narrow-band light is hard on the eyes, and in the bedroom I go to great lengths, (well, lengths of electrical tape, anyway), to cover them over. |
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Especially blue leds — read up on “blue light
hazard”. |
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PWM would be OK, if fast enough, and two coloured LEDs
would allow the same light intensity but changing from one
colour to another. |
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[Rayford] - My bedroom also has bits of black paper taped everywhere to cover the LED's. Electronics stores should sell packs of black sticky paper for $3.95 as an "accessory". |
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Sound beeps should also do this - not "loud - nothing - loud - nothing - loud" but rather "loud - soft - loud - soft - loud". It would be a lot less jarring, and it would be clear when the signal was over, rather than make you wait to hear if there is another beep. |
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Just a note, but the sleep mode on Apple laptops is indicated by something like this (a pulsing LED). In my opinion, however, it gets to bright overall, as it tends to light a room to dark adjusted eyes. |
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No, that’s not this. The heartbeat LEDs on my
Macs
convey a completely different type of message.
The
information payload is fundamentally different to
the simple “blinkenlight” LED that blinks on and
off
to indicate activity. |
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As an example, and still within the Apple realm,
yesterday I set my Airport Extreeeeem to have the
single green LED indicate activity. It certainly
does, but it sucks all the attention in the room
towards it. So do the lights on the ethernet
switch. So do the lights on the BT Homehub. So
do portable USB flash drives, so do
card readers, etc etc and so on. |
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That’s why I had this idea, and not that one. |
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The only thing I actually like having a status LED on is my Tab
(well, it would be nice to have one on that) and my phone. The
way phones do it is usually just to alert you to a missed call,
unread SMS/email, or low battery, where it is then referred to as
a notification LED instead of a status LED. What I despise is
appliances that have a damned status light that's on just
because it's plugged in. Doesn't even have to be powered on
but that damned LED is always lit. |
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Anyways, to the idea. I don't think it'll make much difference.
On notification LEDs, you want it to be harsh on the attention to
be sure it notifies you. On most other electronics that I posses,
the status lights don't blink anyway. They're either on or off to
let you know the status, and when they're off, by damn, I am
GLAD they are off. |
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//unless you drive it as PWM// |
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That would be nifty. On and busy could be defined as 20% and 10% respectively for low light conditions. An optosensor could do that job automatically. |
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You could even use the LED itself as an optosensor. |
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I like to blink when the LED is on. At first this can be quite a chore, but after some practice you forget there was ever a blinking light to begin with. |
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You could try blinking when it was off, but then you'd never
know if it was off. |
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Oh for the days of neon tell-tales, Nixie tubes, dekatrons, and those lovely big black Bakelite quadrant meters .... |
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//So do the lights on the ethernet switch. So do the lights
on the BT Homehub. So do portable USB flash drives, so do
card readers, etc etc// So every one of these needs to be
retrofitted with, at least, a piece of black tape. The Oedipal
solution is much simpler. |
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What if the LED is so bright that when you are trying to
sleep, you can see it through your eyelids?
Black tape on your eyes? |
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Obviously, here is a great marketing opportunity for infra
red LEDs, which can flash as much as they like. |
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//Especially blue leds// blue LEDs are horrible, because they have a wavelngth so much shorter than everything else that they are always (to me at least) out-of-focus. There's a hotel near where I work (where I been for meetings, etc.) which, in a failed attempt to look cool and techy has put rows of blue LEDs along the edges of the steps in its marble staircase - very dangerous. |
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