Talk:Seven-segment display/Archive 1

Archive 1

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)

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)

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)

I've added information on common cathode and common anode connections for LED displays without going down the road of why common anode is more common. But yes, it will be because semiconductor devices generally find it easier to "sink" current rather than "source" it. Colin99 19:36, 29 January 2007 (UTC)

Mechanical 7-seg 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)

Recently added tables of 7-seg symbols

A big thank you! to Crissov for adding the detailed tables! I took the liberty of moving them to a separate section, to improve the readability of the article. I also linked the punctuation marks to their respective articles, but there are a couple of marks that I'm not sure I linked to the correct articles. Please double check my edits, anybody. --Wernher 09:45, 1 March 2006 (UTC)

I have now taken an even greater liberty with the tables, namely of moving them into an article of themselves, seven-segment display character representations. I did this to significantly reduce the loading time of the present article, as well as avoid having the downmost sections being faaaar down below the long tables. I think the tables deserve to have their own article, anyway. I have moved/rewritten some of the explanatory/background info regarding the tables; more to come.

Discussions about the character tables should, from now on, take place on the new article's talk page. --Wernher 07:07, 5 October 2007 (UTC)

Multiple-segment display

In Spain's railway system, on certain railway stations and inside the higher-speed trains, one can see displays employing what appears to be several dozen segments per character, thus giving quite well-formed letters. The technology appears to be old since the letters are either broken or have faded considerably. It would be nice to have a Wikipedia article for that system. As a comparison, France's TGV trains use dot-matrix displays.

Perhaps the fourteen segment display is what is used? I have seen similar electronic signage in the UK on trains, for example Chiltern Railways' coaches. Graham 04:09, 25 March 2006 (UTC)

Diagram needed

Someone added a {{reqdiagram}} to the page - I assume because of the ascii art on the page. I've replaced the ascii art (and I also found a picture of a mechanical 7 segment display) so I'm removing this tag --h2g2bob 21:39, 11 December 2006 (UTC)

Nonsense characters

This whole diagram of how Greek characters, punctuation, and metric symbols are displayed is total unsourced nonsense. I'm planning to remove it if someone doesn't provide any credible objection.

When CD/DVD players use 7-segment displays to say "OPEn" and "PLAY" and "Lo BAtt", that's about as far as it goes. Wikipedia is not for things made up in school one day. I am highly doubtful that any serious device uses a 7-segment display to display any of the things this article claims (like "2 hectares", or "3 picolitres", or "n = x·π". I am a fluent speaker of Greek and also feel pretty sure that these 7-segment list of Greek characters are completely bogus crap somebody just made up. If I'm wrong, then some good references are in order please, before I wipe it out. Reswobslc 05:19, 23 June 2007 (UTC)

I very much agree - go ahead!--Niels Ø (noe) 07:21, 26 June 2007 (UTC)

Mostly LEDs?

The article says:

Most separate 7-segment displays use an array of light-emitting diodes (LEDs), though other types exist using alternative technologies such as cold cathode gas discharge, vacuum fluorescent, incandescent filament, liquid crystal display (LCD), etc.

Is it true that most 7-segment displays use LEDs? Those on watches use LCDs, and most pocket calculators too. I suspect at least a plurality are LCD now. I think this at least needs a source. Mark Foskey (talk) 15:27, 17 December 2007 (UTC)