People that know me know I’m a Tablet PC fan. I love to be able to annotate pdf’s by writing in the margins with a pen. And I really like One Note for writing down my meeting notes or research ideas. It’s great for math, flow charts, etc. It’s the only reason I still use Microsoft (if only Apple would …, but I digress). I recently got a Lenovo Helix. But I had huge problems with calibration of the pen. Here is how I solved it.

(Updated post 01-04-2015 to include instructions on how to remove all calibration data if resetting through the Tablet PC Settings panel doesn’t work)

Before I owned a Dell Latitude XT2 (which replaced my Dell XT) and my first tablet was a Toshiba Portege M220. I really loved the high resolution of the Toshiba, which made me choose the Lenovo Helix this time. Also, the Helix has a detachable keyboard that contains an extra battery that really fits my workflow perfectly. (I travel a lot so I need a real laptop experience many times.)

However, I initially was very disappointed with the Lenovo Helix. It comes with a terribly small pen. This makes it very uncomfortable to write. Moreover, palm rejection basically fails because your palm touches the screen before the screen ‘sees’ the tip of the pen. Moreover, the tip of the pen is very loose, meaning it bends a bit when you touch the screen to write. Quite horrible, really. Not suitable for any serious writing.

However, the biggest problem was the calibration of the screen. When I got the helix and used the standard calibration tool (Control Panel -> Table PC Settings), I could not get it to calibrate such that the cursor followed precisely enough to allow for comfortable writing. This was especially an issue around the edges of the screen, making the pen really unusable within 1 centimetre of the edge of the screen. Not nice if you write in the margins of pdf’s a lot…

I initially thought that maybe the bad calibration was related to the bad pen quality. So I bought a Microsoft Surface pen and a Wacom Bamboo Stylus feel. Although Wacom tech support claims the Stylus feel only works for certain Samsung devices, I can confirm it works with the Lenovo Helix too. However, the Microsoft Surface Pen also works, and additionally has an eraser at the other end of the pen (which the Bamboo Stylus has not). This allows you to quickly erase a mistake you made in applications that support it. One Note and my pdf annotation program do. The Bamboo Stylus feel comes with different pen tips (which the Surface pen does not), which may make it a more attractive choice for other users.

Note that you need to remove the default pen from its dock in the screen for other pens to work! If the pen is in the dock, the digitizer is switched off, apparently to conserve battery power.

Switching to the Microsoft Surface pen resolved the palm rejection issue. Also, it writes much nicer than the small pen Lenovo supplied. But calibration was still terrible. So I searched the web and found some information that helped me to solve my problem. The trick is to use a standard windows tool called tabcal.exe. Tabcal allows you to specify many more calibration points. By using more than the 16 points initially provided when you calibrate for the first time, this really helps to get near perfect pen tracking across the screen.

I ran the command with the following parameters.

tabcal lincal devicekind=pen novalidate
YGridPts=10,60,110,360,660,960,1260,1560,1810,1860,1910
XGridPts=10,60,110,200,330,490,650,810,970,1020,1070

This gives you a grid of 121 calibration points, with most points close to the edges of the screen (to improve tracking in those areas). Note that the parameters above are for the Helix in portrait mode. For landscape, swap the values of the X and Y grid points. Note that you have to decide whether you are going to use the Helix mostly in portrait or landscape mode: calibrating this way erases all earlier calibrations… You can execute this command by using the Windows “Run” program. Make sure to run that as Administrator.  (Again, remove the small pen from its dock in the screen, to activate the digitizer.)

calibrate-pen-device-managerRunning tabcal as described above will fail if the device is already calibrated. The error message instructs you to reset calibration using the Tablet PC Settings control panel item. This may not always work, however. If this is the case, run the Device Manager (again as Administrator). Open the Human Interface Devices section (see figure) and right-click on the HID-compliant pen device and select ‘Uninstall’. Next right-click Human Interface Devices and select ‘Scan for hardware changes’ to reinstall the driver. Now running tabcal as described above should work.

After running this command, and even after a few reboots, I have near perfect tracking of the pen, even upto a few millimetres off the edges of the screen… And I am finally happy with my Lenovo Helix. If only Apple…..

P.S.: Wacom recently also released a driver for the digitizers used in the Lenovo Helix (and the Surface Pro as a matter of fact). Their driver gives you pressure sensitivity support in Adobe Photoshop and other programs (that do not support the new Microsoft pen interface that is standard in Windows 8). I tried it but it didn’t improve my pen precision, and I had the feeling it increased the pen writing lag in One Note. As I don’t really need pressure sensitivity in Photoshop, I stuck with the default Windows 8 driver.

P.P.S.: For annotating pdf’s try PDF Annotator or Bluebeam Revu. I’ve had printing issues with PDF Annotator, and some of my students couldn’t see my annotations. That’s why a switched to Bluebeam Revu. But that one is much more expensive… Your mileage may vary.

P.P.P.S.: For what it’s worth, I really commend Dell for their support. I had tremendous issues with the XT for years. They eventually replaced it (and all the accessories like docking station and batteries) with the XT2 for free!

P.P.P.P.S.: Lenovo should really ship a separate, normal size, Microsoft Surface like pen with the Helix. And it should provide detailed instructions on how to properly calibrate the pen to its users. When I contacted Lenovo tech support about the issue, they said they weren’t aware… (I’ll send them a link to this blog).