Pen pressure

Overview

Pressure is the physical force being exerted on its tip.

Key concepts

  • The pen senses pressure, not the tablet. The pen communicates the pressure it detects to the tablet.

  • The Initial Activation Force is the smallest amount of pressure that an EMR pen will detect and report. More here:

  • The Pen pressure range is the range of physical force the pen is capable of sensing and outputting as pressure. In other words its lower bound is the IAF and its upper bound is the maximum pressure.

  • A tablet splits up the pressure range into a number of segments that are called Pen pressure levels.

  • The pen pressure response is the pen hardware's "pressure behavior" - how a specific pen maps the physical pressure (how hard you are pressing down) to a logical pressure number that is sent to your computer.

  • A pressure curve is a way of modifying or processing the pressure pressure response of a pen. You can do this to solve solve or mitigate some kinds of pressure problems or to achieve certain kinds of creative effects.

  • A pressure dead zone is a ways of using a a pressure curve to effectively increase the IAF.

  • The vast majority of drawing tablet pens are too-sensitive to small changes in physical pressure near the IAF. This means there is some pressure instability at low pressure. You can address this by using pressure curves or pressure smoothing.

  • Tilt affects pressure. The pen is more sensitive when it is held - perpendicular to the tablet surface.

"Under pressure" video series

If you'd prefer to watch, I built the "Under Pressure" video series on YouTube that goes deep into how pressure works. It explores all these concepts in great detail.

Relationship between the pen and the tablet

  • The pressure sensing mechanism is in the Pen, not the tablet.

  • Tablets do play a role in processing pressure. Tablets

    • Determine the number of pressure levels

    • Translate the pressure information from the pen into those levels

    • May process the pressure data before it is sent to the computer

Units

When dealing with the pressure (i.e. the force applied to the tip), the standard unit used in gram force abbreviated as gf.

You may occasionally this force described as grams and see the unit g used. This is technically incorrect, since grams are a unit of mass, not force.

Disabling pressure

Sometimes it is useful to disable pen pressure. For options on how to do so go here: Disable pen pressure.

How EMR pens measure pressure

There are two different techniques. The newer technique involved a pressure sensor in the pen. More here: EMR pressure detection

Notes

  • Pens - even if they are of the same model - differ a little in their pressure sensitivity

  • Pressure sensors are subject to wear. Over time, you may find that a pen is less sensitive to pressure than it used to be. Though in practice, I have never experienced this in any noticable way myself.

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