How much the reflection of the black color in print and paint?
Hello to all optical designers and signboard builders who require anti-reflective black color. I'm Teppei and we develop and sell ultra black anti-reflective sheet "FineShut" at KOYO Orient JAPAN.
Right off the bat, have you ever thought about how the black level for the black painting or black printing on signboards is evaluated?
We are evaluating black level by the index of "Total reflection".
According to its result, the total reflectance of black paint on signboards is from 3% to 10% or so on.
Even the total reflectance of 3% to 10% is good enough for general use, so usually it is no problem.
But there are some applications where you want to suppress the overexposure of light caused by the reflection.
For example, take the 2D barcode. If any part of it is missing due to overexposure, accurate information cannot be conveyed.
In addition, target markers for calibration use must be clearly visible without overexposure at any lighting environment.
Our FineShut SP has a total reflectance of 1.2% in visible light. So, it is far less reflective and is a more black color compared with black painting. Here are examples of improvements by using FineShut as a seal instead of printing or painting. Because the following is based on the actual project, it has been modified a little, then please consider it as only a reference.
Solution for the problem of 2D code sign overexposure
Today's client looks worried about something.
This company has an automatic patrol device using cameras which recognize 2D code signs.
Although it is instructed action by printed 2D code signs, but sometimes recognition errors occur.
It seems that these errors are caused by the overexposure light reflection from the room light.
All right let's solve it by FineShut!!
Let's make Non-reflective signboard !
I can't show the actual 2D code sign, so I made a QR code signboard for my example. I asked for a non-glossy finish print to a major printing service company.
Well, here is the non-glossy panel sample by typical print.
The same pattern is lined up so that you can compare the one with FineShut attached side by side with the one without FineShut attached.
Here is the main problem without FineShut attached...
the reflection. There is so much overexposure, then it can't be recognized as a QR code.
This is caused by the LED light on the ceiling.
So, we will make the right side of this panel to be Anti-reflective by attaching our FineShut.
First, we convert the illustrator file (or DXF or PDF with vector data) of the artwork to machining data for the laser cutting.
Considering making it thinner, we selected the combination of FineShut SP0.2 (t=0.2mm) and thin double-sided tape this time.
The total thickness is 0.27mm. Appearance after laser cutting is like this.
Half cutting was done to the transparent PET separator of the double-sided tape, so this is just tied together by the separator.
From here, stick the necessary parts onto the panel as a seal.
Sorry for forgetting to take photos, but we used a water sticking method when we stuck them. For this sticking method, we added dishwash detergent in the water and this will reduce the adhesiveness for easy positioning.
Because the seal stickiness is low when it is wet, we can easily re-apply multiple times until it is set in the correct position.
Here it is. The right side is treated with Anti-reflective treatment by our FineShut seals. What's that? Can't see the difference?
Well it will be more obvious if you observe from an angle. Finally, an anti-reflective signboard that can protect itself from light reflection, has been made.
The thickness of Anti-reflection area is only 0.27mm, so it seems it is no problem even if you see it in a diagonal direction.
I also filmed a video for easier understanding.
With this, one reflection problem of the two-dimensional code sign was settled. It is also ideal for creating AR markers such as ArUco code.
This is because the parts are cut out and pasted by hand, so I think that a tolerance of about ± 0.3 will probably occur, but products that require accuracy such as camera calibration boards can also be handled by another construction method.
After attaching the fine shut to the panel material specified by us (white mat acrylic board, etc.), only the layer of the FineShut is cut with a laser and the unnecessary parts are peeled off.
If so, such precision ones are also okay. This is a one-stop service for non-reflective panels. It cannot be machined if it exceeds 500 mm, but the processing accuracy is ± 0.15 mm. Please contact us.
Non-reflective treatment of floor-standing calibration board
Next is a non-reflective processing request for a target marker to be placed on the floor. This target marker is for inspection of the camera unit. It's called a camera calibration board that recognizes the displacement of the attached camera unit by looking at the image of the marker.
Similar to the example above, the reflection of the lighting will cause clear highlights.
This request is to be used while being stepped on as it is a target marker to be installed on the floor. It is quite a difficult problem to achieve both abrasion-resistant "black that does not reflect" and "it is safe to step on".
Our FineShut is promoted as "Easy to handle with soft material and feels good to the touch." However, I had never considered stepping on it because it was mainly used for optical equipment. This will be an experiment. This time, we will test with "Fine Shut SP 0.4".
Step on it!
And again! !! !!
After 2000 steps, the experiment was finished. It was a good exercise.
To describe the result, I found no scratches or tears. Although the shoes were dirty, it was easy to clean them.
No luster and no change in light absorption performance. A great result!
After that, like the example of the two-dimensional code, I cut the pattern with a laser and attached it, and made it a non-reflective specification and solved it.
Isn't there a considerable number of uses, such as the expression of holes in trick art, that require both durability and blackness for being stepped on?
Thanks for reading!
Anyone who are having trouble with light reflection by printing or painting method, we recommend you to use our anti-reflective solution "FineShut".
We offer One-stop support from sheet selection to design, cutting and pasting.
Please contact us by e-mail or contact form for your quotation!