How do BOSE make these Awesome LEDs?!

Question

How do BOSE make these Awesome LEDs?!

MrG. (Mechanical)

(OP)

31 May 19 14:05

Hi, I work as a product designer an am trying copy a detail that Bose have on their head phones. Essentially they have what looks like flat black ABS plastic back light with some LEDS. Next to the LED is a printed symbol (Pad printing I think).

How do they create this clever effect with the LEDs?

At first I thought the plastic might have been translucent and that the black coating had been printed on the the outside. However, as you can probably see in the image, I tried scratching away on the top black surface to find that it looks like this whole chunk of material is black ABS. See image attached.

So how do they get the light through?
Is the wall thickness where the LEDs are super thin? But I tried poking the left one and it seems pretty tough.
Is there a hole all the way through the black ABS where the LEDs are and they insert some very tight fitting light guides/pipes?
Any thoughts/comments would be really appreciated. Thanks.

Greg

https://files.engineering.com/getfile.aspx?folder=7b40488f-88a2-4c81-8963-c

EdStainless (Materials) · Answer 1 · 2019-05-31 14:13:07

There are small clear beads of plastic molded into the black body.
Common method, but takes special tooling.

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P.E. Metallurgy, Plymouth Tube

MrG. (Mechanical) · Answer 2 · 2019-05-31 14:25:52

Edstainless, thanks for the reply.

This sounds very interesting, do you know what it is called/have any links about it? I'd quite like to read up on it. Maybe try specify it on a job.

tygerdawg (Mechanical) · Answer 3 · 2019-06-01 14:16:44

Two manufacturing methods that I have seen:

Co-injection of two different materials (in your case, black color and transparent), requires special tooling & machine.
Mold a transparent lens as a separate part, then insert & overmold the transparent lens to the black body part. Special tooling needed.

Perhaps you should consider paying custom injection molding specialists for some consulting time.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com

hendersdc (Mechanical) · Answer 4 · 2019-06-03 21:47:29

Another way I have seen this done is with a dead front overlay or membrane. If you google that term you will see a lot of examples and manufacturers that can make these parts for you.

Here are a couple of the example images that come up with that google search:

MrG. (Mechanical) · Answer 5 · 2019-06-04 09:45:37

Hi both,

Thanks very much for the replies. This is all very interesting. I found one of the website your had commented on which explains it well. It's a good read if anyone is new to this as well:
http://www.rapidkeypads.com/diffuse-uniform-led-ba...

I had spoken to someone else yesterday who said this:

'The ‘hidden’ LED is quite simple. There is a small moulding (usually translucent white) inserted from the ‘B’ surface sometimes with a hemispherical dome that covers the LED diameter. The moulding is pushed into a good fit hole and is sized to fit the wall thickness so that the ‘A ‘ surface of the moulding is flush with the end of the ‘A’ surface of the part. Then a single spray coat of paint is sprayed over the ‘A’ surface (including the end of the inserted piece) usually it is the same colour as the moulding because the film thickness is just sufficient to disguise the insert. When the LED is energised, the light shines through the paint film with sufficient contrast.'

This could be the solution although would the green and white lights shine through very thin black paint so vividly...maybe?

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How do BOSE make these Awesome LEDs?!