Electrical – create a custom LED segment display. What do I need to study?


I want to create and then order a small run of a customized mass-produced LED segment displays for an art project. They will use PWM. It is not much more complex or detailed than a 7 or 16-segment display. But the segment design is different. If I want to design this myself what file format should I be working towards creating? Do I need to plan the pins and internals of the display myself? Are there any examples of what such plans should look like? My understanding is that the inside of a segment display is a sandwich of light diffusers, a one or two sided PCB, and pins.

Are there resistors in there or other electronics? Or is is just LEDS, diffusers and a little routing? I've tried cracking a few apart but it is hard to tell everything that is going on inside.

I do have an EE to help me, but since it's art and I can't pay much I want to do as much of the plan as I can myself and then get advice. But, I'm feeling lost on where to start.

Should I just try making a prototype with resin?

Best Answer

There are two types of LED segment displays. The original, or basic type, simply has LEDs with either a common anode or common cathode. These occupy a small pc board with a set of diffusers and an aperture mask on top. The shape of the apertures defines the shape of each segment. This type of display requires external LED drivers, usually comprising transistors to turn the LEDs on and off, and limiting resistors to set the LED currents. A more advanced type, the integrated display, includes an IC which decodes the inputs to provide the appropriate segment pattern, and also drives the LEDs to the required current/brightness levels.

I believe that you will not be able to afford a custom module. You MUST start inquiries NOW to find out both cost/quantity limits and lead time. I can pretty much guarantee that you will not like what you learn.

If you are trying to roll your own, you should stick to a basic type, that is, you should only provide the LEDs, and count on driving them externally. You can use individual LED modules to create your segments if you are willing to make your segments in whatever shape you can find in LEDs. This may well be circular, square, or rectangular, but your choices of segment size will be severely restricted. If you cannot accept these restrictions, you'll need to make tiny little diffusers, and get someone to make aperture masks using high-contrast transparency film. Then you'll need to assemble the LEDs/diffusers into modules, taking care to optically isolate each segment to avoid light from one segment spilling over to another. Then the aperture will be placed on top of the assembly and fixed in place. I don't know how many of these units you want to make, nor how small you're trying for, but I suspect that you're in for a large effort.

If your segments are large (tenths of inches or more in both dimensions), I'd suspect you're better off getting some perfboard and mounting your LEDs on that, then making isolation cells by drilling into something like 1/4 plywood, then placing a diffuser/aperture plate on top.