Commercial LED backlighting panels in store windows - Page 1
Forum section: electronics / general

author: xrunner
author_rank: Super Contributor
timestamp: February 28, 2022, 11:00:16 pm
content: I just thought these panels were interesting so I took a picture the other day. It's an array of LED panels used to back-light pictures in an abandoned store window. The store was an H&M clothing store in a local mall that is about 90% empty now. They moved out about three years ago and left these panels and the mall left some of the posters in the windows.Where the mall management removed the posters that had "H&M" on them from windows, you can see the commercial LED panels that are behind. They appear to be powered by 24 VDC. You can see the bus bars that connect the positive and negative to the next panel. The LEDs are not in an arrangement I'd have expected (if you go by the lines (traces?)). They appear to be wired in a honeycomb pattern instead of in series. I don't know for sure if the lines are PCB traces or not. I'm also not sure if the "traces" connect to adjacent panels. Has anyone else ever seen these types of LED panels? How do you think the LEDs are actually wired up?

author: Cerebus
author_rank: Super Contributor
timestamp: March 01, 2022, 03:25:18 am
content: I don't think the line that make up the hexagons are traces. Look at the terminals and you can't see traces (and there must be some) and the hexagons don't join up with the terminals.I think it's just slikscreen and I think it's probably there to make sure that people align the subpanels correctly when connecting them together. Look at the corners and you can see that the subpanels don't have rotational symmetry but the terminals look evenly spaced, meaning that you could wire a subpanel in reverse polarity if you rotated it 180 degrees. The mismatch of the lines that make up the hexagons would be a cue that you'd got a panel oriented incorrectly.

author: TerraHertz
author_rank: Super Contributor
timestamp: March 01, 2022, 08:59:58 am
content: The panels have a manufacturer name and details printed on them. Can you go back and take a closeup of that?Or just zoom that part of your image if it can be read.

author: xrunner
author_rank: Super Contributor
timestamp: March 01, 2022, 01:50:26 pm
content: Thanks for commenting.Quote from: Cerebus on March 01, 2022, 03:25:18 amSure that's possible. Seems like you'd only need some unique alignment symbols at the edges but the larger pattern looks good too. But if you try to avoid the "hex pattern" lines and just look at the LED placement, it still seems strange. If I did it, I would put a line of LEDs across. Then the next line would be spaced below with the LEDs halfway between the ones in the first row. Lather, rinse, repeat. Maybe the spacing they used resulted from the designer's research on how the backlighting best looks.I did notice that the center two rows of panels going across are wired together with bus bars, but above and below them those panels are not connected to them. They seem to have a larger space between the panels. Perhaps those sets need another power supply?Quote from: TerraHertz on March 01, 2022, 08:59:58 amI tried to "sharpen" the text but the results didn't look good. I can try another program, or (since I go there three times a week) take another close-up of the printing.I'd like to buy some of those panels from that window. I did know a person in the mall office several years ago, and she allowed me to buy a small utility tray table and a small LED desk light from a long abandoned nail spa - I think I paid $5 for both of them. I don't know anyone in the mall office now, but it can't hurt to ask I suppose. It's a shame that these nice panels are going to go unused for as long as it takes for the poor mall to either re-organize itself into something useful ... or be torn down. From the way things are going, being torn down looks to be the best option.

author: xrunner
author_rank: Super Contributor
timestamp: March 02, 2022, 10:08:32 pm
content: Here's a couple more pics of the panels. The part number appears to be "BT-HC1" or "BT-HC-24VBW65A". I did a quick search but it didn't turn up anything. I did search for "LED backlighting panel" and found many types and examples of this technology, but didn't see these exact panels. I suspect (after looking at what is offered in 2022) that this design may now be defunct, replaced by more modern technology. The H&M store would have started operating around 4 to 5 years ago so these panels were designed before then.The larger panels are marked "A", and I did see smaller panels marked "D". Using my powerful deductive abilities ...I deduce that there may also have been sizes "B" and "C". It appears that they are used to fill up smaller spaces left over after using the large "A" panels. I also now see what may be SMD resistors on the board, but cannot make out the value of them.I decided to go into the mall office this morning and ask them if I could obtain some of the panels. The lady I spoke with said she would ask up the chain and get back with me.

author: PlainName
author_rank: Super Contributor
timestamp: March 02, 2022, 10:26:03 pm
content: Could the LEDs have 3 connections (perhaps 1 NC) and the hexagons are actually conductive heatsinks. That would explain the lack of wires and the pattern, which is just isolation.

author: xrunner
author_rank: Super Contributor
timestamp: March 03, 2022, 03:23:33 pm
content: Quote from: dunkemhigh on March 02, 2022, 10:26:03 pmI don't know at this point. As you can see, there are SMD resistors (I think) but I can't tell how they are being used in whatever circuit there is. If you view a larger pic (once you know what to look for) you can't really tell what rows or columns or other arrangement the resistors are being used in.I need to get a panel and view the rear. I should find out soon if the mall will sell a few to me, but I ain't going to pay a lot for them.

author: thm_w
author_rank: Super Contributor
timestamp: March 03, 2022, 10:10:14 pm
content: Quote from: Cerebus on March 01, 2022, 03:25:18 amYeah hexagon is definitely silkscreen.The panel wont need heatsinking, its 6W and 24 LEDs, so only 0.25W per LED.