The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
User-Agent: Mozilla/5.0 (Windows; U; Win95; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0
X-Accept-Language: en-us, en
Subject: Re: LCD Question
Date: Fri, 01 Nov 2002 14:49:10 GMT
NNTP-Posting-Date: Fri, 01 Nov 2002 09:49:10 EST
Organization: Road Runner
Typically, a 7 segment display is used for clocks, both for LCD and
LED. There is usually a common connection for one side of each digit's
segments, so a 4 segment display gives you 4 connections. All the other
ends of the segments are actually connected together. Only one digit
will actually be "on" at any given time, via the common. The pulses are
timed such that only the proper segments get juice to form the proper
number for the respective digit, all in such rapid succession as to look
like all the digits are "on" simultaniously. Your display may look
something like this. Each "*" indicates one digit, hence one connection.
Then the 7 segments give an additional 7 connections, for a total of 13.
_ _ _
|[_] . [_][_] AM
|[_] . [_][_]
* * * * * *
The backlight is an electroluminescent strip, like the ones sold by
All Electronics. Here is a link to one:
Feel free to email me with any questions. Have fun!
Jack B. Pollack wrote:
> I have several questions about a LCD display in a portable clock that I
> There are 13 'pad' connections on the PC board that connect the LCD display
> 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
> 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.
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup