Quite possible that you are reading this text on a touchscreen phone. Also, might be wondering that how did this phone let to bring this far on Internet? First of all I would say that your curiosity has brought you this far. Secondly, you are going to face a fur smooth and simple approach to understand the working of touchscreen phone. Thirdly, let’s begin 😉
It has always been a matter of curiosity that,
- Are smartphones really smart enough to detect screen touches?
- How does a touchscreen phone works?
- How it transfers the signals from screen when touched?
- Even if it somehow transfers the signals, then what is the screen made of?
- Is it made-up of glass?
- Or it is made of fibre or some other material?
- What does resistive touch screens do?
- How do they work?
- What are capacitive touch screens?
- How do they all work?
- Whats the difference between different touchscreens?
and many other questions quarreling inside your head. Lets draw the answers now.
SIMPLEST Thing (A 4-Step Process):
Step 1: As soon as you touch the screen, it detects the pressure of your finger or any other device that is touched.
Step 2: It transfers the signal to a background layer which always remains in contact with your phone circuitry.
Step 3: The background layer asks the phone circuitry receives some electrical signals and completes the circuit by traversing the signal passed.
Step 4: In turn, the result is returned back to the display screen and thus you see the output.
Diving Into the Depths (A 4+ Step Process):
There are many touchscreen technologies like:
- Projected Capacitive
- Surface Capacitive
- Optical Imaging
Out of these, we are much familiar with resistive and capacitive (both projected and surface).
Resistive touchscreens literally resist your touch. But if you press hard enough, then you can feel that the screen bends slightly. This is how basically resistive touchscreens work. There are two layers in resistive touchscreen phones:
- Conductive Layer
- Resistive Layer
These layers are separated by tiny dots called spacers. An electric current runs through the conductive layer all the time, but when you touch the screen, then resistive layer comes in contact with the conductive layer. The electric current changes at that point of contact and the function corresponding to that contact is carried out. The resistive screens are durable, but its difficult to read them in sunlight because of ambiance effect of light.
Unlike resistive touchscreens, capacitive touchscreens do not use pressure of your finger. Instead, they work with anything that can hold an electric charge. Capacitive touchscreens are constructed by materials like Copper or Indium Tin Oxide. These store electric charges on electrostatic grid made up of tiny wires thinner than human hair. There are three layers in capacitive touchscreen devies:
- A glass sheet (layer)
- A conducting layer (layer)
- A protective coating (layer)
- A controller
- Electrodes at the corners
The electrodes apply low voltage to the conducting layer creating a uniform electrostatic field. When a finger hits the screen, a tiny electrical charge is transferred to the finger to complete the circuit. Also, creates a voltage drop at that point of the screen. The location of this drop is recorded by the controller. Next the process of function calling and rest of the process followed by resistive touchscreens. This is how capacitive touchscreen works.