Thinkpad笔记本指点杆(小红点)自动漂移的问题

Dell, HP, Thinkpad在高端商务机上会配备指点杆(小红点), 有很多人是指点杆的忠实用户, 因为工作时可以双手不离键盘, 非常方便. 在指点杆的使用过程中, 有时候会遇到指点杆自己漂移的问题(trackpoint drifting), 我在T60, T410s, T420s, X240, T550这些机器上都遇到过这个问题.

产生漂移的问题根源是指点杆的校准机制. 这个机制的工作原理, 就是对指点杆连续采样的值进行监控, 如果在一段时间内x轴y轴的采样值保持不变(就像持续受到同一个方向的均匀的力), 程序就会认为这个采样值是本底偏差, 校准机制就会把这个x轴y轴采样值作为静止状态的参考值(类似于电子秤的清零).

这个校准机制可以消除一些硬件模数转换的细微误差, 使得指点杆设备的精度容忍度增大, 哪怕设备静止时采样值没归零也不影响使用. 但是这种机制会引入新的问题, 比如用户刚好在一段时间里均匀用力, 校准机制会误把这个状态当作本底偏差, 于是将这个状态的采样值作为静止状态的参考值, 当用户松开的时候, 就好像受到了相反方向的力一样往反方向运动了, 这就是指点杆的漂移现象.

因为Windows和Linux下使用的指点杆驱动不一样, 甚至在不同版本的Windows和Linux下使用的驱动也不一样, 指点杆的校准机制都有差别. 相比较而言, 与Win10相比, 在Ubuntu20.04下漂移出现的概率更高, 校对时间也更长.

解决办法:

1. 遇到指点杆自己漂移时, 松开指点杆, 你可以用键盘但是不要操作指点杆, 等几秒钟让指点杆的校准机制发挥作用, 漂移就会自动停止. 在漂移速度较快时, 校准需要的时间也更长. Ubuntu20.04下可能要等几十秒.
2. 平时使用时, 不要在一个方向上操作指点杆过长时间, 例如在浏览网页, 浏览代码时, 使用指点杆加中键翻页, 每隔一两秒顿一下, 能预防漂移的情况.

引用一个回复

To preface. This is my 3rd thinkpad. t61p, t530, x1c6.

I'm a 100% trackpoint user. Never use a mouse. I have the trackpad turned off. I use Ubuntu 18.04 LTS currently, but I have another x1c6 which runs Windows 10.

Both my Linux & Windows x1c6 have drift.

Keep in mind, my t61p & t530 both had drift, BUT is was rare and easily fixable by leaving the trackpoint alone while it recalibrates. This was annoying at times, but didn't happen enough to where my computer was unusable at times like the x1c6.

The drift is so bad on my x1c6 that it continously happens for hours, where I feel like I'm fighting with my laptop to use it at times. It can happen immediately after I allow the trackpoint to recalibrate. This happens both on Ubuntu & Windows. It's so frustrating I can barely use my laptop at times. It kills my productivity and fighting against the drift to use my laptop hurts my fingers.

Here's a video of my drift issues https://www.youtube.com/watch?v=_vilgWgUo00

The jerky movements are me, and the slow straight line pulls are the drift. You'll notice in a 1 minute video, I'm able to trigger drift 4 times, after each time letting it recalibrate. This is "just how my laptop works". Great experience.

I can experience drift so bad the speed of the pointer will be so fast, I can't even fight against it and I'll need to let it sit for 20-30 seconds while it sorts itself out. While I'm typing this, I'm still getting slight drift. It happens constantly.

Now I understand low consistant presure can cause drift and require not using trackpoint for a time and recalibrate, but as you see from my video, I'm not performing long low constant presure movements and drift still gets triggered. It's WAY too easy to trigger drift.

I'm considering asking for keyboard replacement or something, because after months of just putting up with this, I'm at my ends. I was fighting attempting to use my computer last night for hours.

参考

• This god damn trackpoint drift is making me mad!