Tech Questions You May Have About Apple Pencil Answered

Published in

Computer Systems MFACA

6 min readOct 28, 2023

Introduction

If you are a visual artist, you must have tried or at least heard of a drawing app on iPad called Procreate. Since Apple launched its first-generation Apple Pencil in 2015, Procreate has become extremely popular in the art community.

As a digital artist and a current SVA MFA Computer Art student myself, the combination of iPad and Apple Pencil has helped me create tons of illustration and animation works that I am really proud of. But in the process of using these marvelous devices, I’ve always wondered: How does Apple Pencil actually work? Why does the iPad pick up my pencil strokes but is not affected by my finger touches? How is it that Apple Pencil requires charging and Bluetooth connection but Wacom pens don’t?

Since I am more of a creative person than a technical expert, I did some research on the principles of the stylus, put together this blog post, and hope that after reading this, you can have a sneak peek into the technology behind ‘the best digital drawing tool in the world’ (said the Apple lovers) — Apple Pencil.

What is a stylus:

To answer these questions, let’s first take a look at some fundamental theories of how stylus works. Stylus is a pen-like tool that can be used as an input device that can help users interact with a touch screen. (Wikipedia says it can also be a pottery tool, but that’s not what we are talking about today).

There are two main versions of styluses: Capacitive Stylus, and Active Stylus.

Types of Stylus:

1. Capacitive Stylus

Capacitive Stylus is a type of stylus that conducts a small amount of electrical charge from the stylus to the screen, just like your finger would. This type of stylus itself won’t produce any signal and does not have any complex components within it. Since it is so simple, some product companies would put it at the end of a normal ball-pen so that it can have multiple functions.

A typical capacitive stylus could look like this

This kind of stylus is usually less accurate and does not offer pressure sensitivity features. Thus, few people use it for drawing these days. But I do miss its soft tactile.

2. Active Stylus

Compared to capacitive styluses, active styluses are more advanced. It usually includes electronic components that allow communication with the device paired with it. This type of stylus enables features such as pressure sensitivity, tilt sensing, palm rejection, or even customizable gestures. They are also considered more accurate and have a low latency response. Both Apple Pencil and Wacom pens are a type of active stylus. But why are they still different?

The reason is that Wacom pen uses a tech called EMR (electromagnetic resonance) and Apple Pencil uses something more similar to AES (active electrostatic).

Apple Pencil vs Stylus: Is Apple’s really better? — WorldofTablet

AES and Apple pencils:

AES uses an electrostatic grid with a special pattern. Both the pen and one of the girds act as the transmitting unit that generates an electrical field. The other grids act as receiving units to help determine the pen’s position. Since the pen needs to actually send out signals by itself, an AES stylus needs to be powered by a battery.

However, the grids of an AES system are placed between the glass and LCD (Liquid Crystal Display) layer, which means that denser girds can have a negative effect on the display quality, making AES tech less sensitive compared to an EMR system. Moreover, Some AES systems also don’t have tilt recognition which can be a problem for digital artists.

Fortunately, Apple does a great job in overcoming the issues with the AES technology. Apple Pencil has tilt sensors built into the device with logic boards and pressure sensors to help measure its position, tilt angle, and pressure. It also uses Bluetooth connection to help achieve palm rejection and customizable gestures such as double tap to change functions. All the elements combined make its latency and sensitivity top-notch in the industry.

EMR and Wacom pens:

Wacom, on the other hand, is famous for its advanced EMR digitizer technology. EMR pens absorb energy waves from the secondary digitizer made of a grid of wires in the screen with is underneath the glass, LCD (Liquid Crystal Display), and touch-screen, and then send a signal back to determine its position, pressure, and tilt. Since they absorb energy from the digitizer, they don’t need batteries to work. Also, because of the fact that the digitizer is placed underneath the display layer, it doesn’t affect the display quality and has great palm rejection features.

Hardware Breakdown of the Apple pencil:

If you’re further interested in the hardware components inside the Apple Pencil, here’s a post I found that has a step-by-step teardown of everything in a 1st generation Apple Pencil.

And here’s a picture of the components of the 2nd generation Apple Pencil.

Hardware components of a 2nd generation Apple Pencil

Conclusion

There you go, now you should have all the answers to the questions listed in the beginning of the blog post.

How does Apple Pencil actually work?

Apple pencil uses AES technology with hardware such as tilt sensors with Bluetooth connection to achieve drawing, pressure sensing, tilt sensing, palm rejection, and customizable gestures.

Why does the iPad pick up my pencil strokes but is not affected by my finger touches?

Apple pencil uses Bluetooth connection to tell the difference between palm and pencil to achieve palm rejection.

How is it that Apple Pencil requires charging and Bluetooth connection but Wacom pens don’t?

The AES technology used by Apple Pencil requires the pencil to send out signals by itself that need to be powered by a battery. Wacom on the other hand, uses EMR technology that allows the pen to pick up energy waves from the Wacom tablet. Thus, it does not require charging or Bluetooth connection.