Why Surface Pro 3 digitizer has 256 levels of pressure? Bashny.Net

Let's start with the electromagnetic stylus h5> 1. Accuracy. These stylus pens can be very accurate, but it strongly depends on the implementation. In order for such a pen worked well on the edges of the screen, the reception circuit board behind the screen should be slightly larger than the screen. Also, metal objects and magnets around the screen, or even near the device is strictly contraindicated, as they distort severely degrade the accuracy. These requirements limit the manufacturer's screen design and materials used. And because the EM field drift depending on the environment, the vendor should be well calibrated digitizer, as well as being taken into account the situation where the user places a metal object in front of the device (eg cover with metal insert).
2. The visual parallax - depends on the thickness of the screen, and none of the technology does not have a significant advantage in this respect.
3. Electronic parallax - as reception fee is buried deep in the device, digitizer pen must calculate the orientation and calculate the position of the orientation. Calculation of position often depends on exactly where on the screen is the tip of the pen. So you can not write a single mathematical transformation for all points on the screen. Few bother it and usually choose some easier way.
4. Stability and accuracy across the screen. The easiest way to check is to take a ruler and draw a few diagonal lines across the screen. Rate evenness lines. Rather, they will not be perfectly aligned, since This is difficult to achieve.
5. The pen itself - its weight, material, ergonomics. EM stylus may be made of metal. They can be any size and shape from thin and uncomfortable (but which can plug into the socket on the device), until more and more like a handle. Even they do not require batteries.
6. Stable and accurate assessment of pressure. Usually with this, EM styluses okay. By the way this is more dependent on the pressure curve than the number of bits reportiruemyh. I will explain in more detail below.
7. Integration with the device - as EM digitizer separated from digital digitizer would need around 0, 4-1mm thickness of several millimeters around the screen and a few tens of grams.

Active-capacitive stylus h5> 1. Accuracy. In the past I've seen here (trans .: in MS presumably) i> is not the best implementation, but I'm very pleased that we have made in Pro 3. We really raised the bar. Perot became much more precise and the entire screen. The first thing I hear from artists who first worked with this pen, it hvalby about the accuracy.
2. The visual parallax - depends on the thickness of the screen, as I said. In Pro 3, we reduce it to 0, 75 mm, and it is one of the lowest numbers that I have seen the tablet with the pen.
3. Electronic parallax - as capacitive line located immediately under glass (which we have only 0, 55 mm thick!), The parallax is small enough, and it's one of the reasons why our feathers are felt more precise.
4. Stability and accuracy across the screen - make test with a ruler!
5. The pen itself - its weight, material, ergonomics. Because we are not limited to pictures, we did klёvuyu adonirovannogo handle from aluminum, which fits comfortably in the hand. Yes, it needs a battery, but a battery can emit a stronger signal, which allows for example, by pressing on the end to open OneNote from a distance of five feet! Not do that with a passive stylus.
6. Delay - as I said, the delay is strongly dependent on the specific application. We really have one problem - he noticed a slight lag, but it is only in the hover.
7. Integration with the device - in comparison with the EM digitizer almost no restrictions. For example, our Type Keyboard cling to sёrfesu by magnets that would hurt the EM field.

Well, as promised, let's talk about the main Fedor about pressure. Some here worry that the 256-level pressure is not enough. You know, because you can promise any resolution, 10, 12, 14, 16 bit ... But in the end, even if the system produces a 16-bit number, it does not mean that it contains 16 bits of useful information. It's like the cameras with sensors of 20 megapixels - there is not always receive a 20 megapixel images useful. You can conduct an experiment that I spent last weekend. I took the best EM-tablet that I know and compare with Pro 3. First I downloaded softinu under the name «digiInfo», which is able to write Windows-message. Configure it to record reports of pressure on both plates. Then I made a small device that held the stylus on the screen and pressed with a force of about 50 g and (lane .: sorry that mix program with Newton) i>. Transcribed reportuemoe static pressure, imported into Excel, and here is what I saw: at EM-pen 1024-th levels, standard otklonienie was three times more than our pen has 256 levels. So, as a result, the performance is the same despite the extra two bits of resolution.
In other words, the pen Pro 3 measures the pressure in the range 10-400 grams and projects into one of 256 levels, and non-linearly as human pressure nonlinearly. But about 1-1 turns, 8 grams per level. A pen-EM measured in the range of 10-500 grams and theoretically receives about 0, 4 grams per level.
...
from the translator:
Then I lost the thread of the conversation. Steve started to talk about balance and about signal averaging.

I>

Think about both those numbers and that is both super super sensitive ... the best weight scale I have can do .1 gram increments .... The only reason it works is cause it averages the heck out of the numbers which adds a considerable amount of lag ... this lag one can not do on a stylus ... so you are stuck with a nosier signal comparatively in a stylus. I> < / blockquote> But after thoughtful analysis, I think he offers to take any precise scale and see how well you can put your finger pressure. He apparently has in mind that 10-bit precision of the pen is excessive, leading to excessive noise, strong signal averaging, and eventually lag. I>

Source: habrahabr.ru/post/224365/