Previously published in the October edition of ECE Magazine, this article written by Helen Francis from Atmel summarizes test results using gloved hands to operate capacitive touch sensors. The article stipulates that the subject must be dealt with on a case-by-case basis, but says that in general, it is possible to use touch panels as human-machine interface, even in environments where gloves must be worn. Read the full article to learn more.
Touch Guy knows that making parts for fighter jets is a whole lot easier than meeting the specifications for the automotive market. There are a few automobile tests that we use to evaluate the effects of temperature extremes on LCDs. The best assessment is the Phoenix test where a car is left in the hottest desert temperatures and everything must work properly when started. The weakest link is usually the LCD, which must meet the 85 degree high temperature range without turning black. In extreme heat, touch panels can become puffy, the coordinates can drift and the sunlight can make the display even harder to read. Once passing the Phoenix test, it is on to the Alaska test with low temperatures where a heater is incorporated into the touch panel to keep the LCD warm and toasty.
Traditionally, most automotive GPS systems have been integrated with 4-wire or 8-wire touch technology. These systems required flexible glass to be incorporated into the top plastic layer in order to prevent puffiness on the surface due to extreme changes in temperature. In situations such as this, a better alternative is 5-wire touch technology which is resistant to extreme temperatures, does not need to be recalibrated and costs the same.
The best solution is to use projected capacitive technology because it provides great optics, no temperature drift, never wears out and you will be able to use the cool multi-touch capability to expand or pinch the map size. Touch International is currently integrating proximity sensing technology into the GPS so that the GPS backlight will dim at night until you get your hand nearby and the brightness will increase based on your proximity.
Stay tuned for details!
Until next time,