Talk:Seven-segment display

Capital N

How do you make a capital "N" with 7 segment display? I don't see how that is possible dispite the article's claim. --Anonymous

See below---capital N to the left, lowercase n to the right. As you see, the "capital N" is really nothing more than a double-height lowercase n. Not obvious at all, I guess.

 AAAA
F    B
F    B
F    B
            GGGG
E    C     E    C
E    C     E    C
E    C     E    C

As noted in the article: to make out some of the letters mentioned requires previous experience and some good will as well, I'd say. :-) We should make an illustrative graphics image of the letters to clarify this. I might do it meself if no one beats me to it. --Wernher 15:35, 15 May 2005 (UTC)[reply]

why the common anode configuration is needed for 7-segment display rather thatn the common cathode configuration

This section was moved here from the article so as to encourage further work on the wording before potential inclusion into the article.
--Wernher 01:43, 1 November 2005 (UTC)[reply]

It is because if common anode is used, the current must be large enough to light on the LEDs. If the common cathode is used, the input will be connected by other IC which may not have enought current to light the LEDs on.

Hmmm, I think what's meant here is that common anode is usually used because NPN open collector drivers are the most common and most convenient. It allows the drive voltage for the LEDs to be different from the power rail of the driver, if necessary. It's easier to sink the required current without needing a high power dissipation in the driver, than it is to source enough current to illuminate the LEDs and minimise power consumption in the driver. This only applies to LEDs. LCD displays can use either common anode or common cathode without any issues since there is negligible drive current. One thing that might be worth mentioning though is that LCDs require an AC (usually square wave) drive to avoid electrolytic effects in the liquid crystal that a DC current would cause. Thus LCD drivers usually have an XOR driver output and a "backplane" drive signal - a frequency of 50Hz or so is usually about right. Graham 04:56, 4 February 2006 (UTC)[reply]

Mechanical 7-segment displays

The section on implementation mentions LED and LCD versions. Gas stations often show their prices in big signs (totems) at the street, and volume and price in small displays at the filling post, using electormagnetic 7-segment displays, where 7 coloured bars rotate to show either a side contrasting with the background, or one coloured as the background. They deserve mention here, I think, but I don't know what they are called. Can someone write this properly?--Niels Ø 10:57, 28 November 2005 (UTC) - - - Here's a commercial site for displays of that type: [1]. I've made the addition myself, using some terminology I found following links from that site.--Niels Ø 11:28, 20 January 2006 (UTC)[reply]