How Do Drawing Tablets Work? Drawing tablets weren’t that popular in their early days. Surprisingly, there has been an upsurge in drawing tablets lately, and their demand is increasing daily.
Drawing tablets have many users, and you might want to grab one too. Most students use drawing tablets for notes, while tutors use them for online tutoring. Apart from school work, organizations use drawing tablets for presentations and artists for digital art.
Now that you know the uses of a drawing tablet let’s find out how they work.
How Do Drawing Tablets Work? the Stylus
Drawing tablets work by being connected to a computer via a USB cable. When you purchase a drawing tablet out of the box, you get a drawing tablet and a stylus pen.
Some tablets come with a rechargeable stylus pen like Wacom Intuos, and others come with removable batteries. When you try to make some strokes on the tablet, you’ll notice that the stylus works like a mouse when the left button is long-pressed.
The only reason you won’t admire the drawings made using a mouse is they look crooked, while drawings made by a stylus look smooth, just like hand drawn.
You’re probably wondering how the rechargeable stylus gets powered. This is a common question, and it even goes further to how the stylus can record button clicks. The drawing tablet has a lot to do with the functioning of its stylus pen. A rechargeable stylus uses electromagnetic resonance technology.
Through this technology, the pen derives power from the drawing tablet.
Drawing Tablets Engineering Overview
We took a sneak glance inside one of our old drawing tablets with the help of our scientists. By exterior design, you’ll think that the engineering work that goes into the components of drawing tablets is straightforward.
Well, it isn’t simple, but we promise to use the simplest terms to explain everything to you so that you understand every bit.
After disassembling a drawing tablet, we came across circuit diagrams and blueprints and tried our best to understand them.
A drawing tablet has two fundamental components:
- Electromagnetic induction
- Magnetic field due to current-carrying wire
When you pass an electric current through a coil of wire, an electromagnetic field is generated around the coil wire.
The opposite of the above statement is also true because when the coil wire encounters a changing magnetic field, a voltage difference is induced.
How does a Graphic Tablet Work?
While most of us believe that position tracking comes from the stylus, it comes from the tablet because the tablet tracks the pen.
The circuitry underneath determines the location that signals are coming from. Below are the components of a drawing table:
- The tablet has horizontally (yellow) arranged wires which capture the movement of the stylus pen along the x-axis.
- Vertical parallel wires (white) detect the movement of the stylus along the y-axis.
- Connection switch circuit switches between the transmission and reception
- The selection circuit selects separate wires along the y and x-axis
- The transmission circuit transmits electromagnetic pulses at an established frequency
- Receiving circuit receives data from the stylus pen
- Processing device helps control the overall operation
Transmission of Electromagnetic Waves By The Pen Tablet
It starts with a transmission circuit where the transistor has an oscillator that generally creates a signal of a pre-established frequency. The transmitter then transforms this continuous signal into a pulse signal with the help of its additional circuity.
The signal is carried to the connection switching circuit to the selection circuit that then distributes the signal to every wire on the y and x axis. Once the signal travels through all the wires, it is transmitted to electromagnetic waves and will be transmitted in all directions.
At the back of the wire grid, an electromagnetic shield absorbs the EM coming to the back. As a result, EM waves are only emitted from the front, where the wave comes in contact with the stylus pen.
At this stage, the tablet prepares to receive a signal after transmitting the electromagnetic wave.
When the pen comes into contact with the electromagnetic wave from the tablet, it encounters a sudden change in the electromagnetic field.
Near its tip, the stylus has a coil of wire that experiences a pulse of EM wave. When this happens, an electric current is induced into the pen.
The induced current determines pen pressure and button presses, then is sent back to the wire coil at the tip.
The next thing that happens is that the coil converts the heavy electrical data into an electromagnetic wave sending it to the tablet through the tip of the stylus pen.
A slight voltage increase takes place when the EM wave emitted from the pen meets the wires in the tablet.
The wires close to the tip experience the most significant voltage increase and taper off as you draw away from the tip. At this point, the processing device instructs the selection circuit to choose the number of coils that have voltage above the predetermined detection level along the y and x axis.
Another thing that also happens is the coil with the highest voltage along the y and the x-axis is selected too. After this, the processing device maps the specific location based on the coils in the y and x-axis, and that’s how the whole calculation takes place.
The electromagnetic waves from the stylus also contain embedded information on button clicks and pressure measurements.
The embedded information from the stylus is amplified and sent to the receiving circuit.
The pressure data is kept in the form of phase difference. Higher pressure levels are stored in larger phase differences, and lower pressure levels are stored in smaller phase differences.
For the receiving circuit to decode pen pressure, it compares the received signal from the pen to the original signal coming from the transmitter. After that, it calculates the phase difference between the two and sends the pressure information to the processing device.
The processing device then reports the pressure, location, and button clicks to the computer, which displays the information on the screen. This process takes place quickly and repeats itself a hundred times a second.
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