Very strange, 19 segment (!) LED indicator by LiteOn. For what purpose it is? - Page 1
Forum section: electronics / beginners

author: LinuxHata
author_rank: Frequent Contributor
timestamp: April 17, 2022, 12:19:08 pm
content: Hello, this is my 1st post hereRecently I've got from a friend in China a bunch of LTP10801HG 19 segment LED modules from LiteOn.They have two strange issues:1. All segments have different number of LEDs inside, and they're in series! There are segments with 1, 2 or 3 LEDS. Which makes driving this module quite complicated.2. The unusual location and shape of segments. While it do looks like typical 16 segment LED indicator at a 1st glance, upon close inspection, there are some interesting details.- there are 4 segments in the middle line, instead of "normal" 1 or 2 segment and one of bottom right vertical segment has small "dot" segment.Googling the part number brings up nothing. So the question is, why they made it into this shape?My initial thought was, that it is all for certain, non-latin language suport. I've searched a lot and found some special segment led displays for Hindi, Bengali, Japanese and some other language display, but none of them looks like these. Any ideas?

author: strawberry
author_rank: Super Contributor
timestamp: April 17, 2022, 01:32:14 pm
content: if its original LiteOn most likely 20y old stock parts. discontinued long long agolarger segment need more light output/more LEDs

author: LinuxHata
author_rank: Frequent Contributor
timestamp: April 17, 2022, 01:55:52 pm
content: Yes I understand that longer segments need more leds to be light evenly. But for example, in LTP8601M, which is bi-color 16 segment display, all LEDs (vertical segments have 3 leds in each) are nicely organized into 6x8 matrix - easy to drive and manage. But here everything is strange.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: April 17, 2022, 01:57:57 pm
content: If you'd pay more attention, you can find out, that indicator I've posted, has 3 extra segments, which are not present in original 16 segment display and are redundant - their presence won't improve visual display of any latin characters.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 17, 2022, 02:20:04 pm
content: The extra segments do improve the form of characters displayed on it.With the normal 14 or 16 segment displays, there are are some thin sections in letters where a tapered end of one segment lines up with the tapered en of another segment.The small extra segments fill up the gap that would otherwise be left by the tapered end points, so either a horizontal or a vertical line can be lighted in the center without a gap.The different amount of LED's in series are obviously to make each segment appear with a similar brightness per area.If the amount of LEDs in a small section would be the same then in a big segment, then it would appear much brighter with the same LED current.It really is no rocket science. Text can be represented readable with a 14 segment display, wile it looks a bit better on a 16 segment display.Some gadgets from the '80-ies era justed 7-segment displays and they managed to make the whole alphabet "readable" on it, although some letters were seriously distorted.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: April 17, 2022, 02:31:24 pm
content: Can you please tell me, display exactly of which Latin alphabet letter is improved by that small part at bottom right? Or which letter can be improved by small horizontal segment on the right?

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 17, 2022, 03:22:35 pm
content: instead of philosophizing over such small details, just make something to drive the display and turn some individual segments on and off, and then determine what looks better.

author: tunk
author_rank: Super Contributor
timestamp: April 17, 2022, 03:23:59 pm
content: Quote from: LinuxHata on April 17, 2022, 02:31:24 pmMaybe L and G?"106THAILAND" could suggest that it's made in week 06 in e.g. 2001.

author: retiredfeline
author_rank: Frequent Contributor
timestamp: April 17, 2022, 03:31:17 pm
content: Quote from: LinuxHata on April 17, 2022, 02:31:24 pmThe digit 4. Some old calculators had this.

author: free_electron
author_rank: Super Contributor
timestamp: April 17, 2022, 03:35:07 pm
content: Quote from: LinuxHata on April 17, 2022, 02:31:24 pmthat should sit on the left ... minus sign.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: April 17, 2022, 03:39:09 pm
content: I already lit up all segments and can't find any characters that will look reasonably better with these extra segments.L really might look better (but not G), as well as 4 (seen 4 like this on old VFD displays), but still, very plausible...For the orientation, the shown orientation is correct - 1st pin is marked and it is on the lower right side.

author: bw2341
author_rank: Regular Contributor
timestamp: April 17, 2022, 03:47:05 pm
content: https://www.maximintegrated.com/en/design/technical-documents/app-notes/3/3211.htmlI don't know if this is the standard font, but let's use this as a reference.The line segments of this LiteOn are very thick relative to the overall character size. This means the gap in the centre on any vertical, horizontal or diagonal line through the middle will be very visible if it were only 14 segments. On the figure in the app note from Maxim, you can see that gaps on diagonal lines are already visible even with thinner segments. Using a dot in the middle on this 19 segment display will give two smaller gaps instead.If you look at the "R" in the standard font, the diagonal leg on the lower right looks too short and overall, the "R" is hard to distinguish from an "A". The LiteOn's segment in the lower right corner will substantially improve the "R".If you look at "G" in the standard font, it is hard to distinguish from the "6" as they differ by a single segment. Adding the horizontal segment that sticks out on the right will substantially improve the "G".You already have a picture of the display so you can try colouring in segments in a graphics editing program to see what the problem characters will look like. You could also redraw the display as a 14 segment and see how much better the 19 segment will look.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: April 17, 2022, 04:02:55 pm
content: Thanks, that is really interesting approach, I never thought in that aspect - I believed that this is was for displaying east Asian languages, so searched there.Have any ideas about this display too?

author: ledtester
author_rank: Super Contributor
timestamp: April 17, 2022, 04:04:04 pm
content: I have a feeling the first was used in an avionics display. I'd ask on a forum where commercial pilots hang out to see if anyone recognizes it.

author: bw2341
author_rank: Regular Contributor
timestamp: April 17, 2022, 04:16:28 pm
content: Quote from: LinuxHata on April 17, 2022, 04:02:55 pmI guess the dot in upper left can help distinguish the "S" and the "5". Filling in the upper left will give the "5" a sharp corner. Leaving the upper left and lower right off will give a rounded and symmetrical "S".

author: Benta
author_rank: Super Contributor
timestamp: April 17, 2022, 05:50:23 pm
content: I'm no linguist, but could it be that it's made for Kanji or some other Far Eastern use?That the LEDs are in series is no big problem, as everyone knows (cough, cough) that LEDs are current driven.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: April 17, 2022, 06:32:34 pm
content: I checked some segment indicators for Japanese and Chinese characters and their segments have quite different shape.Regarding the series connection, the question is, why they choose to do it that way, when in quite similar displays they do use 6x8 matrix ?

author: Hideki
author_rank: Frequent Contributor
timestamp: April 17, 2022, 06:44:48 pm
content: They are for displaying both letters and numbers when you want the letters to be more readable than what a 7 segment display is capable of.Not really useful at all for displaying chinese characters.Here is one example of such a display being usedhttps://www.eventideaudio.com/pedals/space/

author: CaptDon
author_rank: Super Contributor
timestamp: April 17, 2022, 09:32:13 pm
content: For the oddball original ASCII characters including & % $ and the drivers were CONSTANT CURRENT so it made no difference how many LED's were in series. Although these may still be available their original design is very old. I believe these were used in some very early 'crawling message' displays found in places like NASA and NORAD.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: April 18, 2022, 06:51:43 am
content: Yeah, except that with that particular moduleVf @5mA is 2, 4, or 6 volt per segment.Why any normal design should waste 6-2/0.005 power on current limiting resistor for no practical reasons?

author: PA0PBZ
author_rank: Super Contributor
timestamp: April 18, 2022, 10:38:52 am
content: 24 channel constant current LED driver:https://www.ti.com/lit/ds/symlink/tlc5952.pdf

author: CaptDon
author_rank: Super Contributor
timestamp: April 18, 2022, 12:51:50 pm
content: Current limiting done inside the driver I.C. programmed with one resistor. Yes, each of the internal current limiting transistors would create a bit of heat but so did the linear power supplies of days gone by. Again, these were special purpose devices and probably never sold in huge quantities.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: April 18, 2022, 07:47:20 pm
content: I also have LTP8601M - 16 segment, dual color LED modules from LiteOn (with very beautiful, deep red color segments, rarely seen in the 16 segment area). So there are 16 red segments and 22 green (yellow-green) segments. All neatly organized into 6x8 matrix, and can be perfectly driven with TM1639, MAX7219 and tons of other, common ICs. So why they used such a weird way of driving, as in this indicator?

author: thm_w
author_rank: Super Contributor
timestamp: April 19, 2022, 12:48:06 am
content: Quote from: Hideki on April 17, 2022, 06:44:48 pmThats a normal 14 segment starbust display. OPs is 19

author: Doctorandus_P
author_rank: Super Contributor
timestamp: May 10, 2022, 08:27:22 am
content: Some other variations:Segmented Displays558,245 viewsApr 30, 2022

author: LinuxHata
author_rank: Frequent Contributor
timestamp: May 19, 2022, 08:57:49 pm
content: Yeah and some Russian datasheets show even weirder characters, but nothing like that one I have...

author: james_s
author_rank: Super Contributor
timestamp: May 19, 2022, 11:00:32 pm
content: Quote from: LinuxHata on April 17, 2022, 02:31:24 pmA dash between two characters seems like the obvious answer to that.

author: james_s
author_rank: Super Contributor
timestamp: May 19, 2022, 11:02:16 pm
content: Quote from: LinuxHata on April 18, 2022, 07:47:20 pmI don't see what's so weird about it.Those "common" ICs were not nearly as common at one time, and the Maxim stuff has always been so overpriced that it was rare until the Chinese copied it. A huge amount of mass produced devices were made using custom or semi-custom "blob" ASICs or small microcontrollers with transistors to drive multiplexed displays. All you need to drive segments of varying voltages is a different value resistor for some segments than others, easy.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: May 22, 2022, 08:30:28 pm
content: Maybe, but here some segments require well over 6 volts, to have normal brightness, and this is CMOS territory, and these early days, CMOS were not that capable, in terms of amperage....

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: May 22, 2022, 08:54:41 pm
content: Could it be for some other character set, Cyrillic (Russian) maybe ?

author: james_s
author_rank: Super Contributor
timestamp: May 23, 2022, 12:09:00 am
content: Quote from: LinuxHata on May 22, 2022, 08:30:28 pmThat's still easy, use a transistor. It's very common to do multiplexing and use transistors or transistor array ICs to drive LED displays. There are TTL ICs with open collector outputs too.

author: Nominal Animal
author_rank: Super Contributor
timestamp: May 23, 2022, 01:05:55 am
content: Quote from: LinuxHata on April 17, 2022, 02:31:24 pmQ.Quote from: LinuxHata on April 17, 2022, 02:31:24 pmDigit 7 when using the crossbar form, to decisively separate it from digit 1 (which otherwise are confusingly similar).When rotated 180 degrees, the small horizontal segment can indeed be a negative sign, and the small part an apostrophe (') or thousands separator.It seems to me to be quite a versatile design, if you want a single-glyph alphanumeric LED display, especially if driven using a serial-to-parallel latch so that the odd number of segments is not a problem. I'm just a hobbyist, but I'd bet there is a way to drive each element at a constant current using just a few components, using a serial-to-parallel latch and some transistors. (Or, use a serial-to-parallel latch and three ULN2003A's per glyph, with separate current-limiting resistor per element. Or a multiplexing scheme for the same elements in different glyphs. Lots of options; I like this part.)

author: LinuxHata
author_rank: Frequent Contributor
timestamp: May 25, 2022, 04:46:16 am
content: These small horizontal lines at right were found in some VFDs too, used in early Japanese calculators, so it was used as an "improvement" for digit 4, not as a minus sign.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: April 09, 2023, 11:03:29 am
content: Bumping up this again.I've scanned that indicator and created exact visual copy. I'm attaching it here, maybe someone else will have a clue?

author: MrAl
author_rank: Super Contributor
timestamp: April 10, 2023, 09:40:18 am
content: Quote from: LinuxHata on April 17, 2022, 12:19:08 pmHi,I am pretty sure those are displays made by alien Predators so they can show a countdown to when their body bomb explodes in their native numerical notation (ha ha).I looks to me like one possibility is they wanted to try to improve letters and numbers to make them look less "boxy" like a normal 7 segment display looks even for simple numbers 0 to 9.Another possibility is they were made for a particular application with a particular set of characters which would have important meaning in that application.I would think companies would move away from this kind of display now though since so many new types had been invented since the early 1800's when a lot of people couldnt read anyway (ha ha).The best way to find out is to ask your 'friend' where he got them. They could be custom made for a particular application so you would have no way to find out without finding out what they were made for or used for.