Break It Down – How Does The S Pen Work?

February 6, 2013

s-pen-1

Who knows what we’ll see unveiled at Mobile World Congress, but with its recent purchase of five percent of Wacom, Samsung has shown that it believes there is a future in the S Pen.

And why not? It’s a nifty piece of hardware that allows users to do some very interesting things. The popularity of the Samsung Galaxy Note 2 isn’t entirely thanks to the S Pen—a long way from it, actually—but it certainly didn’t suffer because of it either.

Whether you like to use it or not, you may find yourself wondering how the S Pen works. Well that’s what we’re here for.

If you’re in a hurry, check out the three sentence summary, or watch the video.

Where Does The Power Come From?

You might have wondered this already. The S Pen has a button that obviously communicates with whatever Galaxy Note device you’re using, so it has got to require some power, right? One possible solution would be a rechargeable battery that would charge when the S Pen was stowed away, but this isn’t the case. So where does that power come from?

note-2-s-pen-disassembled

The answer: the S Pen pulls the power wirelessly from the device. See, behind the screen is a circuit board, a grid of coils, and a magnetic reflector. Together, these generate an electromagnetic field that emanates outward from the screen. How far does it go? Well, you know how when you move the S Pen close enough, the “hover” icon comes up? Right about there.

Inside the S Pen itself is another coil that channels the power from the field to its own internal circuit board. It uses this power to communicate information from its buttons back to the Note device. And no, that isn’t a type. I said buttons.

The Screen Has Nothing To Do With It

Alright, in the technical sense, maybe it isn’t a button, but that’s the easiest way to think of the tip, or “nib” of the S Pen. See, as the heading just above this paragraph says, the screen has nothing to do with writing, drawing or navigating using the S Pen.

The same electromagnetic field that provides power to the pen can also be used to calculate its position relative to the screen. This, along with information from the S Pen button and the nib on the end are what is used to determine what the user it doing with the S Pen.s-pen-3

If you have a Note device and S Pen handy, you can easily test this for yourself. Pick up the S Pen, push down the nib and move it in close to the screen. You’ll notice that you can draw in the air with the S Pen and it shows up on the screen just as it would if you were using it normally. For another test, take a business card or piece of cardboard, hold it over the screen, and if you’re close enough, you’ll be able to draw on this and see it on the screen.

What About Pressure Sensitivity?

Ah yes, pressure sensitivity. Again, as mentioned above, the screen has nothing to do with it. This is all in the S Pen. For all the levels of pressure sensitivity Samsung touts, I’ve basically only noticed two. Okay, make that three, if no pressure at all counts as a sensitivity level.

It’s interesting though: I personally found that once I knew that all the pressure sensitivity information came from the S Pen itself and not the screen, I was able to get more sensitivity out of it. Note that this still didn’t help my drawing or handwriting skills, but it is still worth pointing out.

Why Don’t More Apps Use The S Pen?

This is a good question, actually. In preparing for this article, I downloaded the S Pen SDK (Software Development Kit) from Samsung and looked through some of the included code samples.

Somewhat to my surprise, the code for using the S Pen was readable and easy to understand. In fact, most of the code can be abstracted away so that developers can add the relevant code to their input handling while leaving most of the rest of the code unchanged.

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Sure, this is easier said than done, especially when you’re dealing with an app that has been updated time and again for bug fixes. Still, it left me surprised that we don’t see more apps in the Play Store with S Pen-specific features, especially considering the popularity of the Samsung Galaxy Note line of devices.

The most likely answer is that the S Pen already “just works” in every app, so unless it can add features that would otherwise be impossible, developers are likely to let TouchWiz make sure the S Pen works for them.

TL;DR

An electromagnetic field is generated from a circuit behind the screen. The S Pen picks this up and uses it to power itself and figure out its position relative to the screen. It sends this, along with information from the S Pen button and the nib at the end, back to the Note.

Videos

Does It Matter?

So, assuming you didn’t already know, you now know how the S Pen works. It’s cool, but is there any practical use to this knowledge? Why yes, as a matter of fact: you can now use a heavy duty screen protector or case, if you wish, without worrying about it affecting S Pen sensitivity.

Is there anything else you’d like to see us break down? Would you like to see more detail? Less detail? Let us know in the comments below.

Comments

  • Kyle Hetzel

    Wow, great article! One of my friends has a Note 2, and I was wondering how the S Pen works! Thanks!

  • http://www.facebook.com/spaine.carinan Spaine Carinan

    This was the first video that I’ve seen about how the S pen work. I kinda searched for how the s pen works cause I was curious sometime ago, now I can sleep in peace.

    Keep up the good work!

  • http://www.facebook.com/osama.a.hasan Osama A. Hasan

    I’ve bought a cover for my note-II and when I draw on the screen using apps such as sketchbook Pro with the S-Pen I’ve noticed that there are some lines that are “shifted” from its place (making a shape of empty small circle) in the middle of the screen and I was worried but then I realized that the problem was caused by the covers’ magnet (in the back of the note-II that used to hold the other end of the cover) it was conflicting and distorting the electromagnetic field of the actual phone so the S-Pen was picking a”false fields” up and uses it to figure out a false position :)

    SO BE CAREFUL WHEN YOU ARE BUYING A NEW COVER

    great article, Thank you so much for letting me know how my mobile works

    • cu@femacamp

      Bloody brilliant observation Osama, I was wondering what the hell was at the bottom of my note 2 screen distortion error which was just applicable to the S Pen, and samsung support had no idea. I thought it had something to do with screen pressure as it was ‘reset’ when I changed the bezel, leading me to believe it had something to do with screw pressure. The leather clip case!!! Incidentally I waved the magnet on my case over the distortion area after seeing your message and voila! It seemed to even it out. Now to cut off the magnet clip cover. (It’s either that or get an expensive bit of mu-metal to shunt the EM field away from the phone!)

      • focusp

        I found that cutting off the magnet was not enough as my cover has a magnet in the back as well as the one on the flap that closes it. So I had to remove the whole cover and not just cut off the magnet to fix it. The cover supplier still has no idea that the magnet is causing interference with the S Pen a year after that post.

        What a great article on how the S Pen works thank you.

  • DragonsKindler

    So it works exactly like my Wacom tablet?
    :-P

  • w_p_w

    Well done on the article and the video, keep em coming ;)

  • http://twitter.com/KrRay03 Kaushik Ray

    I can die peacefully now..!!! Great one dude..!!

  • Rav

    it was good to know how the amazing s pen works. keep up the good work Android Authority

  • crnell

    why some people choose to sleep/die peacefully after knowing how s-pen works ? :D

  • http://www.facebook.com/kees.staps.1 Kees Staps

    Thanks and keep the info coming

  • thinsmek

    Thank You

    • Guy

      Thanks a lot for the info!! I am a new owner of a GT-N8010 and I like to know how it works!

  • http://AndroidAuthority.com/ Bogdan Petrovan

    Great post, Kris.

  • Chiew Yeik

    amazing!!!!

  • 路人

    我寂寞寂寞就好 這時候誰都別來安慰擁抱
    就讓我一個人去痛到受不了 想到快瘋掉
    死不了就還好

    我寂寞寂寞就好 你真的不用來我回憶裡微笑
    我就不相信我會笨到忘不了 賴著不放掉
    人本來就寂寞的 我總會把你戒掉

    • Twisted247

      Ya what he or she or it said above me : ) … imagine writing those symbols out with your s-pen

    • Twisted247

      Those symbols truly are amazing though. I have always had something for hand writing since I was younger and still have it today. I admire nice hand writing don’t know why. But these symbols above are fascinating to me.

      • vilecrud

        you were Japanese in a past life perhaps?

  • http://twitter.com/adam2evans adam evans

    good video personally id like a little more technical and you should do something with that nice green wall you have continently behind you!

  • Mimi R

    U failed to mention the button on the s pen

    • Joshua

      I would like to know too. Like does the switch change the binary state of the pen which allows the phone’s software to know that it has to use different functions?

  • mike

    great video,man! and amazing technology!
    we live really in the future!

  • humanfly

    I have the first Note and I’ve lost the S pen twice. The second time was pretty much the day after I bought the new one. I’ve bought a third, with the intent of using a Dremel to drill a teensy-tiny hole in the very tippy top of the pen, and do the same to the Otterbox case I have, and connect the two with fishing line or a small wire lead. What are my chances of damaging the pen when I drill a teensy hole in it’s butt end?

  • muchenjeri

    It is refreshing to find tech writers who actually provide information, rather than tech punditry. Thanks!

  • Jordan Anderson

    Thank you!

  • Emre Z

    You noticed 2 levels of pressure? lol… i must say i’m using a smartpc pro with an s-pen for digital sketches and it works nearly as good as a wacom tablet. I hope Samsung keeps working on the s-pen products! It is a must-have for an artist…

  • Simon Belmont

    I liked the video. So, I hope you do more.

    The article, itself, was a good read as well. Cheers.

  • gdv

    if it has nothing to do with the screen then can it work on other devices if we supply a power source too it??????

  • jazyeee

    Great article, does s-pen work with galaxy note 2 from Samsung Korea, which has simple stylus rather than s-pen?

  • Sunil

    This was really informative. :)

  • STUDENT

    EXCELENT INFORMATION THANKS A LOT

  • Michelle Steele

    Thank you so very very much. I’m so grateful you provided such awesome videos and explaining it so even I understood what you were saying. I’m hooked on Android Authority!!

  • Pitoyo Amrih

    The screen has nothing to do with it.. so, does it mean that the Samsung S-pen an work in every capacitive touchscreen?

    • Chris

      The screen has nothing to do with it but the hardware beneath it does. Which means only Note series are able to detect the pen usage.

  • Rijo Mathew

    Fantastic piece of engineering..

  • Dude

    Q? What would the cause of a S Pen suddenly not working at all on a Galaxy Note 10.1 as a example? I have got my S Pen working by re-flashing or back dating, then updating again to make the S Pen work, but out of the Blue, the S Pen just stops, and I find I can use my finger to draw or write, but the S Pen does not function. Why or What would be the cause of this exactly??? Its a good question but I have found no logic to why as yet on the web. Can you assist? BTW, thnx for the doco on how the S Pen works. Can you do one on why the S Pen does not work please?? LOL pretty please? :)

  • Jay Brahmbhatt

    How S-keeper work ??

  • Manic Zombie

    Awesome Break Down, keep up the good work.

  • Dele

    My s pen works with other devices(galaxy note 1 2 3 and galaxy note 8000) but it is not working with my device( galaxy note 1)..please help

  • Talha Ashraf

    Great work dude . Keep it up

  • Mo

    I’m a subscriber to your YouTube channel and I’m a fan of Android Authority. I really liked this article and the videos that you made explaining the nature of the S Pen. I honestly am impressed by the technology that went into making this Stylus. and I’m a happy owner of s Galaxy Note 3. One of the main reason I upgraded from Galaxy S2 to Galaxy Note 3, is actually the S Pen. I really like what it does and it makes the mobile experience a lot different. I mean let’s be frank, our fingers don’t have a fine and pointy nib that can address such sensitive screens, so when I need to do something with a lot of accuracy and precision, i definitely use the S-pen. I really love it.

    Thanks for your article and your videos.

  • Johnny

    More Note 3 details, please!!! Anything and everything about this device; I am interested in. I absolutely love it! Tweaks, changes, enhancements if you will; post ‘ em all!!!

  • Alex Gallagher

    Great explanation. I use a normal screen protector and was worried how it might effect things so thanks for clearing things up for me.

  • R. Adams

    Very good article! Thank you very much for the information.

  • Bruce Logan

    Amazing.

  • Nik

    Now break down the new S pen of Note 3 please and tell us what has improved since its last iteration.

  • Jay

    Can you drill a hole in head of s pen to add a pieace of paracord to access it easier, I don’t have nails so it’s a little hard getting to my pen?

  • Kristian Kofoed

    Hi — does the S-Pen work with the Surface Pro 2?

  • Phred

    Actually I was so fustrated with the s pen that I tossed it in the rubbish. I know several others who did the same. The pen is very sensitive to the enviornment. It often inks when I am not touching the display.

  • TTech

    i lost my s pen and not my screen isnt responding to the touch of my finger. Why is this?

    • TTech

      now*

  • Rinley

    ‘”Just works” in every app’ – HAH! Game after game after non-multitouch game after game after game FAILS to use the S-pen in any capacity, period. No navigation, no icon tapping, NOTHING. It is 100% useless in most of my games.