For battery capacity limited device, what is the 'sweet spot' duty cycle and frequency to drive LED at highest energy efficiency (high brightness using low energy) for human active observer for attention-seeking guide light.
Instead of ON all the time, human visible persistence mean one can see the light even if it is a short pulse.
My question is how short (duty cycle) the pulse that huamn can 'feel' good brightness compare with 100% on time. Extreme example is xeon flash in film photography to freeze motion. On time is kind of 0.1 to 1ms. Traditional LED bed side clock is 4 digits driving 25% duty cycle.
To clarify, this is NOT blinking rate. Say, 3 blinks per second then 3 seconds off.
For three blinks per seconds, "167 ms light up and 167 ms no light", repeat 3 times.
Here, I am seeking advises for during the 'light up' 167 ms. One way is LED on for 167 ms. Another way is says, "167 ms with 25% duty cycle", "42 ms on, 125 ms off"
Many thanks