> Greetings,
>
> pls point me to site that have this information about time division
> multiplexed for LED display. i'm having hard time understanding how they
> scan out a character. thanks.
>
> regards,
> ckchan
>
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> I don't know of any site but this is basically what it is doing.
>
> The human eye has a scan rate of about 50 frames per second.  That means
> that if you flash something less than 50 times per second (lets pick 20),
> you will see the pulses or flashing.  Above 50 times per second (lets say
> 70), the human eye will see it as being constantly on. Knowing this, we can
> flash out LED display at a rate faster than 50 times per second and won't
> notice a thing.
>
> Time division multiplexing means that we only display 1 digit at a time.
> First we display the one's digit, then we display the 10's digit, then we
> display the 100's digit, then we display the 1000's digit, etc.  If we can
> display all the digits (one at a time) more than 50 times per second, you
> shouldn't notice any flicking.
>
> You will have two sets of control lines to handle this.  One will be the
> digit information and these lines will all be tied together at each
> display.  You will have a seperate set of control lines telling which digit
> we are displaying at any given time.  Only one of these lines will be active
> at any one time.  This 2nd set of control lines connect to either the common
> anode or common cathode depending on what type of LED display your useing.

> anode or common cathode depending on what type of LED display your useing.
>
> ckchan wrote:
>
> > Greetings,
> >
> > pls point me to site that have this information about time division
> > multiplexed for LED display. i'm having hard time understanding how they
> > scan out a character. thanks.
> >
> > regards,
> > ckchan

>

>
> >I'm not sure why this is, but if you stand facing a mirror and hold a
> >digital clock with the display facing the mirror (so you can see its
> >reflection) and move it around quickly, often you can see the individual
> >numbers broken apart.
>
> It does not need to be in a mirror. If you have a calculator or digital
> watch with LED display and wave it about in front of you while looking at a
> fixed point you can see this effect.
>
> Another effect that I have noticed is that a TV screen will show flicker
> when seen out the corner of your eye. Peripheral vision is much more
> sensitive to these effects, and does not have the "afterglow" effect of
> straight ahead vision. The other effect I have noticed is when there is an
> oscilloscope screen off centre of vision, it is sometimes possible to get
> the effect of the spot scan being stopped mid screen when you move your
> head. This is somewhat dependant on the scope scan speed and the direction
> of movement of your eyeball relative to the trace scan direction.
>