A guide to how drawing tablets work

Whether you are just starting out or are an experienced digital artist, understanding the basic principles of how your drawing tablet works and the actions that they are capable of can help you get the most out of your tablet and troubleshoot any technical issues when they arise.

A drawing tablet, also known as a graphics tablet, pen tablet or illustration tablet is a computer input device that is specially designed to capture a hand drawn image or a signature. A drawing tablet can also be used in place of a computer mouse when navigating a computer. Alternating between computer input devices can help a user avoid repetitive strain injury.

The drawing tablets consist of two main parts: the tablet, which is a flat surface to draw and trace on with a pen-like stylus or puck. The image is either displayed on the computer screen or in an incorporated LCD display.

Drawing tablets are commonly categorized based on the type of stylus technologies that different manufacturers use. There are four broad types of drawing tablets.

Passive Tablets

Passive tablets use electromagnetic induction technology; the tablet contains a printed circuit board that is inlaid with a grid of send/receive coils and an attached magnetic reflector. The grid alternates between transmitting and receiving modes approximately every 20 microseconds. In transmitting mode the tablet generates an electromagnetic field.

The accompanying stylus contains an inductive coil, capacitor resonant (LC) circuit, a circuit board and a pressure sensor. Many styluses also contain buttons, which allow the user to set custom commands, usually the type of tool such as pen, eraser, pencil or brush.

When the stylus is brought within range of the field generated by the tablet it stimulates oscillation in the coil and capacitor resonant circuit inside the stylus. The received signal passes through to the circuit board along with information from the pressure sensor and the switches on the side of the stylus. All of this information is then encoded and sent back to the tablet from the resonant circuit as a data stream when the tablet switches to receive mode.  

The information sent back to the tablet is analysed by the computer in order to determine the position of the stylus along with other information such as pen pressure, speed, tilt and the type of tool selected by the switches on the side of the pen.

As the grid within the tablet provides the power to the pen through resonant inductive coupling, no batteries are required. The electromagnetic signals mean that tablet can detect the location of the pen without the pen even touching the surface of the tablet.

Brands that use passive technology include Wacom and Parblo.

Wacom Intuos Draw CTL490DW Digital Drawing and Graphics Tablet

Active Tablets

Active tablets operate in a very similar way to passive tablets, however they use a battery to power the stylus. As the stylus transmits it’s own signal the tablet does not alternate between send and receiving modes, instead it constantly listens for the pen’s signal. Powering the pen is designed to result in less stuttering, however it does add weight.  

Active tablets require the stylus to touch the screen of the tablet to generate and transmit a constant signal to the tablet.  

Brands that use active technology include XP Pen, Huion and Ugee.

XP-Pen Star05 Wireless 2.4G

Capacitive Tablets

Capacitive technology is commonly used in touch screen monitors and devices including smartphones and some tablet computers. A capacitive tablet includes a layer of material that stores an electrical charge. Touching the screen with a finger or a stylus disrupts the electrostatic field creating a change in capacitance; this is due to the conductive properties of the human body or the accompanying stylus.

The information generated by the change in the electrostatic field is analysed by the tablet to determine the location, pressure and tilt of the stylus or touch input.

Brands that use capacitive technology include Wacom, Turcom, Huion.

Ugee Pen Tablet Review

LCD Tablets

More advanced and expensive drawing tablets typically incorporate an LCD display directly underneath the drawing surface. The most significant advantage of the LCD display is that it closely replicates the natural experience of drawing on paper; the user sees the location of the pen in direct relation to their design instead of looking at the computer screen.

LCD tablets can use active, passive or capacitive input technology.

Brands that offer LCD drawing tablets include Wacom, Parblo, Huion, Ugee and Yiynova and XP Pen.

Passive Tablet.

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