Capacitance Sensors for Human Interfaces to Electronic Equipment
Mechanical buttons, switches, and jog wheels have long been used as interfaces between users and machines, but their many drawbacks have led designers to look for more reliable solutions. Capacitive sensors, which can be used in place of buttons, can also add versatility. Available ICs can measure the capacitance of up to 14 sensors, compensate for environmental changes, and provide a digital output.
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8 Comments:
I think this is a good article. Please teach about using it in touch screen applications, like CRT or LCD.
Easy to understand, enlightening... Makes you look forward to using this kind of device.
An article about touch-screen controllers can be found at http://www.analog.com/library/analogDialogue/archives/35-04/touchscreen/index.html
well written, easy to understand, good ilustrations. Thanks.
Is the chip described here adaptable to distance sensing rather than touch sensing for a 30 cm range ?
@RB: This product is designed for user input touch sensing applications; it would not be suitable or capable of doing long distance sensing greater than 3 cm.
Hi,
Thanks for this article.
But I would like to understand one point of your article. You said : "When a user comes close to or touches the capacitance sensor, the measured capacitance decreases or increases."(as shown on the green graphic)
I don't know how the capacitance measured can decrease, I thought that user's finger could only increase the capacitance detected by the sensor.
Thank you (sorry for mistakes, english isn't my native language)
ADI's parts implement two types of capacitance sensing. With self capacitance, where there is an increase in capacitance when the user comes close to the sensor. (AD7147 and AD7148 products). We also have mutual capacitance sensing parts : in this case, the user shunts some of the capacitance measured away from the RX sensor electrode, so a decrease in capacitance is measured at the RX sensor.
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