Traditionally, styluses and touchscreen pens have been used for touchscreen devices such as tablets and game consoles. They are a tool used to navigate, engage with or even create content. Styluses and pens have come a long way, so let’s take a quick look at the technology behind the screens before moving to the pens, and jumping to technologies for the future.
Types of Touch Technology
There are two main types of touchscreens: resistive and capacitive. Resistive touchscreens rely on mechanical pressure to function and sense touch. They are typically made up of a number of layers, one clear poly-carbonate layer on top that you interface with, and two conductive layers which are separated by spacer dots. When you press down on the poly-carbonate layer, it pushes the conductive layers together, and sensors detect the voltage change to determine position. These are generally used for screens that do not offer complex operations, or are often preset. Some typical examples of resistive touchscreens you may encounter regularly include the Nintendo DS, shopping mall maps, GPS devices, and older touch displays in cars.
Capacitive technology, on the other hand, doesn’t need mechanical pressure. Instead, it is coated with a conductor agent, and when a human finger or capacitive stylus touches the screen, it causes a change in the electrostatic field, which can be measured in voltage, and tracked to determine position. Most modern day smartphones use capacitive touch.
Resistive touchscreens have the advantage of being cheaper to produce. They’re also able to be used with any physical pointer, be that a finger, paper clip or even the pointy end of a chopstick. Generally, higher end products will want to use a capacitive touch screen, for more durability, sharper images, and multi-touch functionality.
Pushing Pen Powers
Moving on from screens to the pens that write on them, current pen technologies fall into two categories – electromagnetic resonance (EMR) and active electrostatic (AES).
The underlying principles are similar to what we discussed before. Changes in electrostatic fields create a measurable voltage that can be traced to a location. EMR technology uses a field of sensors in a grid that emits a weak electromagnetic field. The pen affects that magnetic field, which the device uses to determine its location, orientation and pressure. One key advantage of this technology is that the pen itself is not powered.
Active electrostatic technology, as the name implies, requires some form of active power. It operates on similar principles of electrostatic changes, but with a more powerful manipulation of the fields. This reduces the sensitivity of the device, but increases its robustness.
Handheld Motion Sensing – Form and (Added) Function
Modern digital pens need to be able to streamline their users’ needs. They also need to meet the needs of ever-increasing desires for an intuitive and complete user experience. This is why companies are connecting their pens to their devices using RF protocols. Handheld motion sensing is one of the foremost tools for achieving this, utilizing inertial sensors to translate hand motions into precise pointing and intuitive gesture controls.
Say you’re giving a presentation and “all you have” is your laptop’s active pen. No problem. With motion sensing, you can command the presentation with your pen. Move the cursor to highlight items in your presentation and interact with your content with no added hardware, capability impossible with a typical presenter.
If you’re creating a new digital work of art, moving between tools on screen with a traditional stylus can be a drag (literally). But imagine, in mid-stroke, twisting the pen to change the width of your digital calligraphy. Or making a quick circle gesture to bring up a color wheel without leaving that area of that detail you’re working on. Or maybe a quick shake of the pen to erase the last few strokes? With this type of functionality, drawing can be less… drawn out.
When editing photos, tweaking color scales is a common task. With a stylus that integrates handheld motion sensing, you can do this easily by rotating your pen like a knob to control the sliders with precision, and flicking to change between color settings. Depending on the application context, the same rotating motion can be used to zoom in to the perfect amount to touch up your work.
Whether it’s giving a big presentation, illustrating a new piece of art, editing some photos, or any other pen-based computer application, the functionality of the digital pen can be improved on with an integrated IMU and sensor fusion.
Our team at CEVA is developing a growing list of features for use with stylus pens, set-top box remotes, game controllers, smart phones, and AR/VR controllers, and PC peripherals in our MotionEngine Air product. Features include:
- Point and click cursor control
- Event classification (such as Pick-up, Stability, onTable)
- Gesture recognition (such as Flick, Shake, Circle, Twist)
- Virtual controls