Improving the keyboard background light

[EvilDragon]

Nope, this is not yet the pre-preorder link (still got a bit of time before that), but as Nikolaus tested the keymat with the real unit, it's time to report back on that.

Unfortunately, the backlight doesn't work as good as we hoped yet, but we are already working on improvements.
Right now, we have 1 LED for four keys - but the light is not diffused enough to properly lighten up all keys.

There are multiple solutions to fix that:

• Increase the amounts of LEDs
• Try to find a keymat material that improves light distribution (I know there are foils, but I don't know if rubber can be created in the same way)
• Change the keymat so that only the key top is colored with black. This will improve the light distribution A LOT, but will also mean that the surroundings on the keys light up as well (which is the case on mostly every backlit keyboard I've seen, so no big deal).

We'll probably do a mix of all of those.
Instead of 1 LED for 4 keys, we'll use 1 LED for 3 keys. The downside is that this will increase the costs of the Pyra a lot... by 0,40 EUR.
Power consumption wouldn't be a problem, as each LED wouldn't need to be as bright as before, so each LED needs less power.

I've also asked the company to check whether there's some material available that distributes the light better.

Only printing the keys in black is easy as well: The mask needs to be changed so that only the tops will be covered with color.
The reason this improves lighting a lot is simple: The further away you are from the LED, the larger the area the LED actually emits light to.
You can easily check this with a flashlight yourself: Make a spot on the wall. The closer you get to the wall, the smaller the spot gets.
If you move away, the spot gets bigger.
Right now, the black paint stops the light of the LED after 1mm. If that's removed, then the light of the LED will go all the way to the top of the keymat - which is about 7mm further away. The spot becomes bigger, the lighting is more evenly distributed.
This is planned to happen next week and shouldn't delay things, so we're still planning November for the prototypes

I'll keep you informed, as usual!

 

[comradekingu]

Is it possible to glue something ala the 3M foil that edge-lit LCDs use to distribute light to the PCB?

Highter intensity LEDs or more voltage to them? Maybe something that distributes light in a different radiation-pattern?

Edit: Will putting the black layer farther up make for less durability since you can wear it down quicker?

I think less complexity and risk is the winning move, lighting up only the letters sounds classy.

 

[Jumpman]

Thanks ED, little issues like this are to be expected, and no surprise really. Thanks for the update, and I'm sure it will be worked out in short order.

It's so nice to have manufacturers close by, that don't take months to ship things back and forth. Just being able to fix little issues in a timely manner is worth any and all cost to have more local vendors. Great work, looking forward to actual assembled prototype videos.

Chris

 

[comradekingu]

Idea, how about a white PCB, will that improve anything?

 

[EvilDragon]

Is it possible to glue something ala the 3M foil that edge-lit LCDs use to distribute light to the PCB?

Highter intensity LEDs or more voltage to them? Maybe something that distributes light in a different radiation-pattern?

Edit: Will putting the black layer farther up make for less durability since you can wear it down quicker?

I think less complexity and risk is the winning move, lighting up only the letters sounds classy.

Yes, I thought about the 3M foil. But any added thickness would increase the travel distance, so it would need be be way thinner than 0,1mm.

Higher intensity LEDs won't help much - they would still be spotted, so the black color would just eat more light.

The black layer is no layer - it's just paint. So it's either everything that's covered with the black paint or only the key tops. There's nothing inbetween.

 

[levi]

Oh no, an extra 40 eurocents?  That's it, I'm out!

Having the key surrounds light up sounds fine to me, by the way.  As you say, that's already the case on most backlit keyboards.

 

[EvilDragon]

Oh no, an extra 40 eurocents?  That's it, I'm out!

Having the key surrounds light up sounds fine to me, by the way.  As you say, that's already the case on most backlit keyboards.

And probably also the reason for that

 

[Neelix]

Only printing the keys in black is easy as well: The mask needs to be changed so that only the tops will be covered with color.

The reason this improves lighting a lot is simple: The further away you are from the LED, the larger the area the LED actually emits light to.

You can easily check this with a flashlight yourself: Make a spot on the wall. The closer you get to the wall, the smaller the spot gets.

If you move away, the spot gets bigger.

Right now, the black paint stops the light of the LED after 1mm. If that's removed, then the light of the LED will go all the way to the top of the keymat - which is about 7mm further away. The spot becomes bigger, the lighting is more evenly distributed.

Would this really help that much?   The black paint is only on the surface.   I would have thought that instead of being blocked by the paint the same light would just instead be blocked by the case.   What am I missing?

-Neelix

 

[fusion_power]

Hm, the easiest way is to find a better keymat material instead of re-doing the PCB. The idea with the white PCB also seems legit. Or leave the labeling transparent completely, only black paint surrounding.

 

[derpybox]

by 0,40 EUR.

Highway robbery!

 

[EvilDragon]

Hm, the easiest way is to find a better keymat material instead of re-doing the PCB. The idea with the white PCB also seems legit. Or leave the labeling transparent completely, only black paint surrounding.

If there does exist a better material.
The PCB doesn't need much redoing. Just a few LEDs more.
 

Right now, the black paint stops the light of the LED after 1mm. If that's removed, then the light of the LED will go all the way to the top of the keymat - which is about 7mm further away. The spot becomes bigger, the lighting is more evenly distributed.

Would this really help that much?   The black paint is only on the surface.   I would have thought that instead of being blocked by the paint the same light would just instead be blocked by the case.   What am I missing?

Yes, it does, we can already see that with the old unpainted samples we got.

I'll try to show you:



This is a side-view of the keymat.
Those two green things should be LEDs.
The left one has the paint on the full keymat.
If the LED would be right below the button, the light would go further up - but that won't work (you couldn't press on the LED )
So the LEDs are placed in the middle of three keys, with no key directly above it.
If the mat it fully painted, the light would emit as far as on the left LED - and then only a tiny bit gets into the button cap itself.

The right LED would be an example if only the top of the keycap is painted.
The light would emit through the full keymat, through the buttons itself until it reaches the top.
Therefore, the area it lights up is a LOT larger.

 

[Neelix]

Right now, the black paint stops the light of the LED after 1mm. If that's removed, then the light of the LED will go all the way to the top of the keymat - which is about 7mm further away. The spot becomes bigger, the lighting is more evenly distributed.

Would this really help that much?   The black paint is only on the surface.   I would have thought that instead of being blocked by the paint the same light would just instead be blocked by the case.   What am I missing?

Yes, it does, we can already see that with the old unpainted samples we got.

I'll try to show you:

View attachment 12415

This is a side-view of the keymat.
Those two green things should be LEDs.
The left one has the paint on the full keymat.
If the LED would be right below the button, the light would go further up - but that won't work (you couldn't press on the LED )
So the LEDs are placed in the middle of three keys, with no key directly above it.
If the mat it fully painted, the light would emit as far as on the left LED - and then only a tiny bit gets into the button cap itself.

The right LED would be an example if only the top of the keycap is painted.
The light would emit through the full keymat, through the buttons itself until it reaches the top.
Therefore, the area it lights up is a LOT larger.

I have a hard time understanding exactly what's at what level on that cutaway view, but unless the keymat is going to be a solid block of rubber with that black paint layer somewhere in the middle I'm pretty sure it won't work the way you are envisioning.  My point here is that since the paint is on the outside of the keymat, any light absorbed by the paint layer is light that would be exiting the keymat  at that point anyway, so removing the paint there wouldn't actually facilitate it's transmission any futher through the keymat itself.     I think you'd be better off instead painting those areas of the keymat in an opaque white,  so as to reflect as much of the currently absorbed light as possible back into the keymat material itself.

-Neelix

 

[DAP]

Black paint absorbs light. Put down a coat of white paint under the black paint so the LED reflects off the white paint.

 

[fusion_power]

If there does exist a better material.

I'm no expert but I suggest to just ask for a more transparent silicone/rubber material.  From the pix you posted, the underside of the keymat looks just white and in no way transparent enough.

I'm sure there are standard methods to successfully light up an ordinary keymat. No need to re-invent the wheel.  
If the rubberm aterial is transparent enough, it should guide the light pretty well through, even with a black layer of paint on top. From the pix we can see that the underside is not painted so the light should spread freely there. Not sure if the distance to the top of the buttons is to big. Unpainted Mat would work better but does not look that well I guess. This is what ED means:
http://bettersilicone.en.made-in-china.com/product/yvfQXslKnJRe/China-Silk-Screen-Elastic-Rubber-Silicone-Keypad.html

We have this kind right now:
http://bettersilicone.en.made-in-china.com/product/evTnXMixYJpO/China-Laser-Elastic-Rubber-Backlight-Silicone-Keypad.html
and since these types can work pretty well, I prefer these ones actualy. ^^
 

 

[levi]

Strictly speaking, white surfaces absorb and re-emit light in all directions.  As opposed to reflective surfaces, such as metals, which re-emit incident light in a direction symmetrical about the surface normal to the incident light aka. reflecting it.

I've no idea whether ED's idea of not painting the edges will make enough difference.  It should let more light out from under the keymat, but whether it will come out in useful places will need to be tested.

 

[EvilDragon]

If there does exist a better material.

I'm no expert but I suggest to just ask for a more transparent silicone/rubber material.  From the pix you posted, the underside of the keymat looks just white and in no way transparent enough.
 

Making it more transparent will make things a lot worse because the light will be less diffused and you simply see the LED through the mat, without any area lighting 
I'll try to find some early pics, where we tested all that.

 

[fusion_power]

.If there does exist a better material.

I'm no expert but I suggest to just ask for a more transparent silicone/rubber material.  From the pix you posted, the underside of the keymat looks just white and in no way transparent enough.
 

Making it more transparent will make things a lot worse because the light will be less diffused and you simply see the LED through the mat, without any area lighting 

I'll try to find some early pics, where we tested all that.

Hm, but I've seen other rubber mats that are more transparent. Maybe you just have to find the "sweet spot", I'm sure there is an good compromise between transparency and light diffusing. From the pix in the link I posted, it seems these mats are semi-transparent, a little bit in the beige direction but not plain white.

http://www.better-silicone.com/Translucent-Silicone-Backlit-Switch-pd016125.html

"Translucent Silicone Backlight Keypad take full advantage of silicone original materials which is translucent. Different silicone is different transparency. Generally, more better silicone materials, the color is more transparent. The original color of liquid silicone is almost transparent."

 

[bismuthdrummer]

The top layer being black should make a big difference. Any light that escapes from behind the keymat and tries to bounce around that layer gets basically nowhere between the black of the keymat and the back of the case. Remove the black layer, and you now have more reflection from the top and refraction going through the material that can escape around the keys. The result will be more bleeding as ED noted, but that should be acceptable.

An appeal to imagination:
https://youtu.be/MmeOIYr4yjM?t=2m9s

Now imagine the whole keymat (minus the black keytops) glowing like the keys do. That's how much light is lost from that top layer, assuming there aren't more translucent materials around the keys. Looked like the rubber was slightly different right around each key, so I'm not 100% here.
 

 

[EvilDragon]

.If there does exist a better material.

I'm no expert but I suggest to just ask for a more transparent silicone/rubber material.  From the pix you posted, the underside of the keymat looks just white and in no way transparent enough. 

Making it more transparent will make things a lot worse because the light will be less diffused and you simply see the LED through the mat, without any area lighting 

I'll try to find some early pics, where we tested all that.

Hm, but I've seen other rubber mats that are more transparent. Maybe you just have to find the "sweet spot", I'm sure there is an good compromise between transparency and light diffusing. From the pix in the link I posted, it seems these mats are semi-transparent, a little bit in the beige direction but not plain white.

http://www.better-silicone.com/Translucent-Silicone-Backlit-Switch-pd016125.html

"Translucent Silicone Backlight Keypad take full advantage of silicone original materials which is translucent. Different silicone is different transparency. Generally, more better silicone materials, the color is more transparent. The original color of liquid silicone is almost transparent."

This is a totally different thing you're showing here.
Of course, with less transparent material, the brightness is lower. Brightness is not an issue. Area coverage is.
And that's why you need more diffuse material.

This picture is also a good example why removing the black painted layer is the correct thing to do:
If you take a look at those cubes, you can see that light emits from the sides as well. The emitted light actually lights up the surrounding area, which can also clearly be seen here.
A black painted keymat has THESE SIDES closed as well. So no light will get there.

BTW: One of my daily life work is properly lighting scenes.
You can believe me I know how light behaves with different material. And using a diffusor foil to make the light more soft and less spotty is a common thing.

 

[Christoph.Krn]

BTW: One of my daily life work is properly lighting scenes.

You can believe me I know how light behaves with different material. And using a diffusor foil to make the light more soft and less spotty is a common thing.

Could you point me to some resources where I can find some high-quality information about these things?