How do capacitive touchscreens work

How do capacitive touchscreen work

In the world, more than 4 billion people use smartphones. They are incredibly powerful and complex devices that can do so many different tasks. One of their main component is the screen, as more than 90% ot the cellphones have one. The touchsceren is not just a screen, but a main way to interact with the device. But how does the screen finds out where we place our fingertips?

What is a touchscreen

A display is an electrical device that displays different colors organized in such a day that it can display many different symbols, digits, images, and more. The display consists of few major components – LEDs (or light emitting diodes), a motherboard, backlight, and more. The display works by changing the color of each LED according to the information given by the electrical components.
Displays are composed of millions of small LEDs which you might know as pixels. Each pixel is a single LED element. And the resolution is the total amount of pixels for the display. So a 1080p resolution would mean 1920×1080 which is 1920 individual LED on each row, and there are 1080 rows. If we multiply that we get 2 073 600 pixels. Depending on the DPI (dots per inch) or the size of the display and each pixel a display with a size of 10″ can have as little as 640×480 (or 307 200 pixels) or for instance 3840×2160 (8 249 400). The difference being in the size of the pixels or DPI. The more DPI a display has the smaller the pixels are. Which represents a clear and better-looking image.
A touchscreen is simply a display that you can interact with, by touching its surface.

Types of touschreens

There are two major types of touchscreens that are used in modern devices.

Resistive touch screen – this type of screen is earlier technology, as is basically made of 2 layers, one layer is resistive and the other is conducting. They are separated by spacers. An electric current flows through the conductive layer, and it can be changed by pressing the surface layer which is the resistive one. When they come in contact the electric current changes, this is detected by the device and it knows where on its surface is being pressed.

Capacitive touch screens – these are the main type of displays found in most modern devices with a touch screen. It doesn’t require pressure to know where you have touched on its surface, as it works by detecting a change in capacitance on its surface by any object that conducts electricity – such as the human finger. Their main components are glass and conductors such as copper. The copper is used to create a grid. Electrodes apply voltage on the conductive layer and create an electrostatic field, so when a finger touches the screen a charge is transferred to the field and completes the circuit. This creates a voltage drop, and the controlled of the device notes where on the grit that drop happened, so it can detect the position of your touch.

Advantages and disadvantages of different types of touch screens

Since capacitive touchscreens rely on the touch of a conductive object to work it senses the electrical field change. The disadvantage is that you can not operate this screen with gloves for example. You would need to touch the display with something that conducts electricity, there are pens and even touch screen gloves as they are specifically designed to work with capacitive touch screens. The main advantage is that they do not require actual pressure just a touch, they are durable and can work even if the screen is damaged.

The resistive touch screens are better in outside environments as they do not require conductive object, and you can operate them in different weather conditions and you can do it with your gloves on too. They often are used in GPS units and other devices. They are used in different environments as they do not require to be touched with a naked hand.