Capacitive Touchpad
   
 
Q1 :  What is capacitive touch sensor?
Q2 :  Which types of capacitive touch sensor ICs does ELAN offers?
Q3 :  How to process the board level design of the capacitive touch sensor?
Q4 :  What communication interfaces can ELAN's capacitive sensor ICs support?


  Answer
Q1 :   What is capacitive touch sensor?
  A:Capacitive touch sensor is a dust-proof, fire-proof, scratch-resistant, and durable sensor with high resolution feature. Applications of capacitive touch sensor technology is quite broad. Most significant and practical applications are in the following sectors: 1) Banking Sector (ATM or ticketing machines), 2) Health Care Sector, 3) Public Information Sector, and 4) Entertainment Sector. The theory behind the capacitive touch sensor technology is very simple. When a finger tip approaches or touches the sensor panel, existing capacitance of the touch panel will increase by about 5%. An IC monitors and measures the amount of actual capacitive change within the 5% capacitance. The IC then transforms the data into digital signal and transmits the information to the applied device.


Q2 :   Which types of capacitive touch sensor ICs does ELAN offers?
  A:ELAN provides various types of capacitive touch sensor ICs for variety of applications, i.e., button type, single-dimension type, two-dimension type, and wheel type. Button type:is used to virtually perform the traditional mechanical push buttons functions in such devices as cell phones, remote controls, and computer keyboards. Single-dimension type:is used as slider to control audio volume and screen brightness/contrast, and perform menu selection function. It can also be used to execute mouse scrolling functions. Two-dimension type:is applied as touch-pad for laptops and as handwriting recognition sensor for cell phones. It is also used with ITO touch sensor screens (e.g., ATM interactive screen). Wheel type:is mainly applicable to iPod and MP3.


Q3 :   How to process the board level design of the capacitive touch sensor?
  A:First choose the board material to use. Currently, the most common board materials are PCB, FPC, glass, and film. Of these materials- PCB is usually used for applications with flat surface, such as laptops, MP3s, etc. FPC, which is the most expensive, is usually used in applications that involve curved surfaces (such as mouse). Glass and film, being transparent materials, are mostly used in display screen/panel applications. In order to maintain screen display quality, ITO is coated on the glass or film surface to produce the capacitive sensor overlay.When designing the capacitive touch sensor panel, take note of its capacitive value and the thickness of its insulator cover. Sensitivity is affected if the capacitive value is too high or the cover is too thick. This may also cause difficulty in determining the correct amount of capacitive change when the sensor is touched. As a general rule of thumb, the cover thickness tolerance for each type of touch sensor ICs is as follows: – button type has the highest tolerance; single-dimension type has a medium tolerance; and the two-dimension type the lowest.


Q4 :   What communication interfaces can ELAN's capacitive sensor ICs support?
  A:Depending on the application type, ELAN sensor ICs provides the following communication interfaces: PC peripherals:PS/2, USB, Quadrature Consumer:UART, SPI , I2C. I/O For more information on the supported communication interface and its specifications, please refer to concerned IC product specifications.