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X-Mailer: Mozilla 4.78 [en] (Windows NT 5.0; U)
Subject: Re: LCD Question
References: <email@example.com> <firstname.lastname@example.org>
Date: Sat, 02 Nov 2002 10:19:07 GMT
NNTP-Posting-Date: Sat, 02 Nov 2002 11:19:07 CET
Organization: Telia Internet
Have you tried to search for the data sheet on the web? Any pdf can be found
If there is a large black circuit near the connection to the display...search
for that number...
Or connect a 10 kohm resistor to a +5 Volt (or a segment nearby) on the PCB and
try to find the connection.
"Jack B. Pollack" wrote:
> Thanks Wafer & Gary ,
> Both of your posts were helpful. From Wafer's post I envisioned the whole
> process as a data and address type of scenario for each digit, but was
> baffled when I masked out with tape one of the contacts to find what
> appeared to be random segments disabled.
> Gary's post was right on the money 'it is not even on a digit basis'.
> Now that I understand how this works let me try to ask a little more
> specific question:
> We have a really nice Jacob Jensen digital clock that only displays time in
> 24 hour format, this drives my wife crazy. When I opened the clock I found
> a hardwired jumper to set the time format.
> The clock now displays time in 12 hour format, but the display lacks a PM
> indicator making the alarm function useless.
> I am sure that the 'blob' is outputting a signal for PM, but how do I find
> it (In a data/address scenario I would have looked for it on the 'digit'
> with the other indicators ('Alarm on', time set, etc)? But since segments
> are 'random' how do I find it?
> Secondly, I was going to drive a small low current LED for the PM indicator.
> I dont think this will work based on the explanation of the 2 square waves.
> I guess I could NAND them and then use the NAND as a driver for the LED (I
> dont know if the square wave voltage is too low to drive TTL). Any
> suggestions on indicate PM would be appreciated.
> Thanks again
> "Jack B. Pollack" wrote in message
> > I have several questions about a LCD display in a portable clock that I
> > have:
> > There are 13 'pad' connections on the PC board that connect the LCD
> > to the PCB and 'blob chip'. If I look at these connections with a scope
> > there is a square wave on each of them.
> > The display has no electronics in it, how is the data transferred to the
> > display and decoded? How are the individual segments on the display
> > addressed?
> > The second question is about the LCD backlight:
> > There is a thin film (looks like a piece of paper) with 2 contacts on it.
> > When 50V AC is applied the film glows blue and backlights the LCD. I would
> > like to find out more about this type of backlight technology and how to
> > build a similar driver circuit for the backlight.
> > Any insight would be appreciated.
> > Thanks
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