Don’t use 7-segment displays (2011) [pdf]

Re:Don’t use 7-segment displays (2011) [pdf] by tal8d on Sunday March 07, 2021 @02:24AM (#26373965)

Yeah, the HDSP-2132 is a common display component in military hardware. I'm sure that readability figures into it (especially for NVGs), but so does hardiness. My hopes of an 80x24 dumb terminal were dashed when I finally learned the unit replacement price... I don't need a rad hardened serial display that bad.

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Re:Don’t use 7-segment displays (2011) [pdf] by parsecs on Sunday March 07, 2021 @02:33AM (#26374013)

I've been looking into those Avago/Broadcom dot matrix displays recently. I don't think it'd be too hard to recreate something similar with tiny SMD LEDs on a PCB and a slightly intelligent driver board, for much cheaper. Would there be a market for something like that?

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Re:Don’t use 7-segment displays (2011) [pdf] by exmadscientist on Sunday March 07, 2021 @02:48AM (#26374069)

Only if you can get them listed at Digi-Key/Mouser/etc. Even if it's under a "maker" brand like Adafruit, Sparkfun, etc. Anyone who can replacement TIL311 and friends displays in there, and advertise them, will sell quite a few.

They're not hard to make, but they're the sort of thing that no one really wants to make in-house, since they're a means to an end rather than an end in themselves. Great thing to sell, though!

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Re:Don’t use 7-segment displays (2011) [pdf] by tal8d on Sunday March 07, 2021 @02:49AM (#26374071)

It has been done a few times, but I doubt there would be any kind of market for it. https://hackaday.io/project/85515-redotmatrix

Electroluminescent glass panels on the other hand... https://www.youtube.com/watch?v=Z2o_Sp2-aBo

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Re:Don’t use 7-segment displays (2011) [pdf] by zokier on Sunday March 07, 2021 @09:52AM (#26376244)

That redot project seems like perfect candidate for a kickstarter

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Re:Don’t use 7-segment displays (2011) [pdf] by mng2 on Sunday March 07, 2021 @05:42AM (#26374795)

In grad school I taught a electronics lab class where the students would burn through a bunch of HDSP-0772 every semester. I thought about coming up with a replacement, but at the time you could still get them for a somewhat reasonable price (like $10 or $20?).

At today's price of $50 it might be cost effective to do as you say, but I imagine there's not a huge market.

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Re:Don’t use 7-segment displays (2011) [pdf] by tyingq on Sunday March 07, 2021 @09:09AM (#26375934)

That would be roughly a 0.75mm pitch.

Not rad hardened, and not quite 0.75mm, but you can buy a 1.25mm pitch LED matrix panel for a relatively low cost. It's an RGB panel instead of monochrome for the HDSP-2132.

https://www.alibaba.com/pla/Hot-sale-small-pitch-led-display...

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Re:Don’t use 7-segment displays (2011) [pdf] by tal8d on Sunday March 07, 2021 @12:46PM (#26377911)

Unless I'm misreading the page, it is claiming a resolution of 104x78. So that means 8,112 LEDs.

The HDSP-2132 is made of 8 character elements, each element has a resolution of 5x7. So a 80x24 terminal would have a resolution of 400x168... 67,200 LEDs.

So about a magnitude off, even before ignoring the built in character spacing :)

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Re:Don’t use 7-segment displays (2011) [pdf] by tyingq on Sunday March 07, 2021 @02:06PM (#26378707)

I wasn't suggesting one of them would settle the matter. I was suggesting it would be cheaper to use them instead. They are made to be grouped together, and daisy chained to a single controller.

I believe each module would be 160 x 120 dots (19,200 dots total) though, based on module size and LED pitch. I'm unclear on where you got 104x78.

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Re:Don’t use 7-segment displays (2011) [pdf] by tal8d on Sunday March 07, 2021 @03:52PM (#26379653)

> I'm unclear on where you got 104x78.

https://www.alibaba.com/product-detail/Hot-sale-small-pitch-...

    Module  Res     Size
    P1.923  104*78  200*150

I went ahead and counted... 128x96 (12,288 LEDs)

https://imgur.com/a/4qdY1Pr

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Re:Don’t use 7-segment displays (2011) [pdf] by tyingq on Sunday March 07, 2021 @05:03PM (#26380213)

It's just bad pictures and errant info.

Here's a better link: https://www.aliexpress.com/item/32965783207.html

It's 160x120, as I mentioned for a 200x150mm P1.25 led module. You just divide the width/height by the pitch to see the number of dots.

As far as I can tell, 1.25mm is the smallest pitch available for these modules.

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Re:Don’t use 7-segment displays (2011) [pdf] by tal8d on Sunday March 07, 2021 @07:23PM (#26381109)

lol, I marked every tenth led manually and counted twice - the number is correct, the marketplace is wrong.

https://imgur.com/a/NqVXtDd

https://www.mblock.com.tw/upload/Investor/events/2020/202008...

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Re:Don’t use 7-segment displays (2011) [pdf] by tyingq on Sunday March 07, 2021 @07:44PM (#26381221)

You counted dots on a picture of something other than a "200mmx150mm P1.25 led module". Pitch is the distance between the center of each LED.

1.25mm x 160 = 200mm

1.25mm x 120 = 150mm

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Re:Don’t use 7-segment displays (2011) [pdf] by parsecs on Sunday March 07, 2021 @12:09PM (#26377550)

Is over $100 that low cost? Surely there could be better prices.

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Re:Don’t use 7-segment displays (2011) [pdf] by tyingq on Sunday March 07, 2021 @03:14PM (#26379352)

19,200 RGB LEDs plus all the mux chips adds up, but these signage modules are significantly cheaper than anything else with discrete separate LEDs.

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