What is a capacitive keyboard?
A capacitive keyboard is a type of computer keyboard that uses a change of capacitance on a keyboard’s capacitor pad to detect a pressed key. This type of keyboard provides functionality similar to a standard mechanical keyboard, but its internal structure makes depressing a key quicker and quieter.
What sensors do keyboards use?
Optoelectronic keyboards use a light source (usually infrared), and a light detector (e.g. photo-resistor) to detect the presence of a key press.
What is capacitive sensing method?
Capacitive sensing is a technology based on capacitive coupling that takes the capacitance produced by the human body as the input. It allows a more reliable solution for applications to measure liquid levels, material composition, mechanical buttons, and human-to-machine interfaces.
Do capacitive touch sensors work?
How Capacitive Touch Sensors Work. It’s called capacitive because the technology is based on capacitive coupling that detects anything that is conductive or has a dielectric different from air. In this case, the human body (your fingers) is being used as an electrical charge conductor.
Are keyboard keys capacitors?
Under the keyboard s keys are capacitors that store electricity as opposite static charges in pairs of conductive plates made from nickel-plated copper that are separated by a non-conductive material (typically some form of plastic).
How does a capacitive keyboard change capacitance?
Upon touching a capacitive switch, this electrical charge disturbs the switch’s own electrical charge; thus, causing a change in capacitance. Because of this change, the switch can identify when and where the touch occurred, which is essentially how capacitive switches work.
What are the types of keys on the keyboard?
The keys on your keyboard can be divided into several groups based on function:
- Typing (alphanumeric) keys. These keys include the same letter, number, punctuation, and symbol keys found on a traditional typewriter.
- Control keys.
- Function keys.
- Navigation keys.
- Numeric keypad.
What do capacitive sensors detect?
Capacitive sensors are most often used to measure the change in position of a conductive target. But capacitive sensors can be effective in measuring presence, density, thickness, and location of non-conductors as well. Non-conductive materials like plastic have a different dielectric constant than air.
Can capacitive sensor detect plastic?
Capacitive sensors detect both metal and non-metal objects, and can sense through insulating materials such as wood or plastic. They are often used to detect fill levels of liquids, pellets, and powders through container walls.
What are the typical capacitance values of capacitive keyboards?
A typical capacitive sensor has a value of 10 to 30 pF. Typical finger coupling capacitance to the sensor through 1 mm of insulating overlay is in the range of 1 to 2 pF. For thicker overlays the coupling capacitance decreases.