There are different types of e-writers. Dedicated e-writers may not have many features beyond allowing you to take notes or fill out forms on a screen. Many tablet devices have apps that record notes or translate handwriting into text. But though there are dozens of variations, most e-writers do share a few traits in common.
One of those traits is a touch-screen interface. This is what lets you jot down your thoughts on an electronic device. The job of the touch screen is to detect and track your touches. There are several ways to do this but most e-writers use either a resistive screen or a capacitive screen. Both types track you using electricity.
Resistive screens detect touch through pressure. A resistive screen has several layers. The top layer, which acts as the device's touch surface, bends as you press on it. This makes it come into contact with lower layers. When the layers touch, they form a circuit. A weak electronic signal passes through and the device detects a touch. Moving the point of pressure around the surface changes the contact point and the device tracks the movement.
A capacitive screen doesn't detect pressure. Instead, it detects changes in an electric field whenever a conductive material makes contact with the screen. Your fingers -- along with the rest of you -- are conductive. Even the lightest touch on a screen will cause the electric field to change, registering a touch.
There are advantages and disadvantages to both types of screens. Resistive screens tend to be less expensive to produce, driving down the cost of the gadgets. They also tend to detect touches with more precision than capacitive screens. And you can use anything to interact with a resistive screen -- your finger, a stylus or any other object that can apply pressure to the screen.
Capacitive screens only work with conductive material. If you're wearing regular gloves or using a standard stylus, you won't get a reaction from a capacitive screen. But capacitive screens tend to respond faster than resistive screens. And while a standard stylus might not work with one, there are electronic varieties that are compatible with capacitive screens. Unlike resistive screens, capacitive screens won't wear down as you use them.
Not all e-writers must expend energy to detect a touch on the screen. Let's take a look at how some liquid crystals can record your notes.