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The operating principle of the capacitive keyboard is based on the electrical variation
that occurs when the user approaches the finger to the glass. With just approaching
the finger there is already an electrical variation detected by the system. However, for
the selection of the function to be effective, it is necessary to press on the key covering
with the finger its maximum surface, thus creating the effect of pulsation.
The software is responsible for immunizing the keyboard from the effects of water that
may remain on it. For this the system performs a series of individualized readings of
each key obtaining a reference value for each one of them in the environmental condi-
tions (humidity, more or less water on the keyboard, but without the finger). When you
press the key with your finger, this reference value assigned to the key is far exceeded
and the function is pressed and started.
If we move the finger little by little to the key, it will not cause the key to be pressed, be-
cause the device assimilates it to a variation of the environment. Also, until we remove
the finger for a few seconds, the key will not respond adequately to a new press.
The slow increases in capacity are considered variations of the environment and the
rapid ones that are considered user pulsations. Thus, the approach of the finger to the
key must be fast, the energetic pulsation and covering the entire surface of the key.
When several keys are pressed at the same time, the device decides the one that was
most pressed or the one that was previously pressed, since by reliability several pulses
are not allowed at the same time.
When one or several keys are pressed (or excess water) more than 25 seconds, the
logo flashes red indicating an anomaly that the keyboard has something on it (a wet
towel for example) that must be removed or cleaned.
If water is poured on the keyboard and it remains stagnant, several keys may be pres-
sed. To eliminate this effect, it is enough to remove the water.
There are factors that modify the sensitivity of the keyboard:
- The more finger surface touches the crystal, the greater the capacity variation.
- If the keyboard has a thin layer of water it will be less sensitive since this water film
increases the reference value.
- A layer of water can cause a different key to be pressed than the user wishes since the
water being conveyed transmits the variation of capacity to all the keys it covers.
- The fact that the user is inside the bathtub filled with water can increase the responsi-
veness of the keyboard.
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