== Air Logic == When consumer products like cars first needed complex controls systems like central locking and power windows, electronics were in their infancy. Electro-mechanical relays were large, hot, loud, expensive and unreliable. This was solved instead mostly by the use of "air logic." Compressed air (or sometimes vacuum) systems use miniature 3- and 4-way air valves to fulfil the needs of the logical components and, or, not, yes, and flip-flop as well as timers and delay mechanisms. Users turn dials or push buttons which feed data into the system via air instead of electricity, and the control system actuates power controls which cause air or electrically-driven accessory controls to function. Some even used these to control engine accessories, like air conditioning, fuel timing, and emissions controls. While it continues to be used today, it's only for specialized industrial uses. From the 1970s onward, the now cheap and reliable integrated circuit began replacing air logic and cars were really the vanguard of the all-electronic world we live in. When I encounter an air logic system, I often imagine a long-retired engineer with a shelf of industry awards and books; the father of air logic, now forgotten due to the march of technology. This book is about portable touchscreen devices--from small handheld mobile phones through to writing-pad sized tabets. I started writing in late 2014 based on research begun in 2012, NOTE ABOUT GOING OUT OF DATE... Keep yourself educated, keep up to date with trends and technology, and never be so in love with a particular solution, or way of working that you lose sight of the changing world. == History of Touchscreens == Mostly how they are not new. Very brief overview. Give Apple due credit, but no more. Following from my (and others') Wikipedia entry. Users must be able to accurately select targets on touchscreens, and avoid accidental selection of adjacent targets, to effectively use a touchscreen input device. The design of touchscreen interfaces must reflect both technical capabilities of the system, ergonomics, cognitive psychology and human physiology. Guidelines for touchscreen designs were first developed in the 1990s, based on early research and actual use of older systems, so assume the use of contemporary sensing technology such as infrared grids. These types of touchscreens are highly dependent on the size of the users fingers, so their guidelines are less relevant for the bulk of modern devices, using capacitive or resistive touch technology.[29] [30] From the mid-2000s onward, makers of operating systems for smartphones have promulgated standards, but these vary between manufacturers, and allow for significant variation in size based on technology changes, so are unsuitable from a human factors perspective. [31] [32] [33] == Capacitive Touch == From articles and presentations, include inaccuracy, calibration, s/n tradeoffs, edge dropoff (moto study with grids). Photo of Casio grids to show size, etc. Images from moto test rig if I can get them, photo of Alison's phone with grid visible, nearby, to explain this is not microscopic scale at all. List of upsides/downsides to it. I am glad I was not very well known back in the early 2000s so you can all go and quote how misguided I was. Capacitive screens were on a few mobile devices before the iPhone, and many people—including myself-thought they were very silly for reasons that are still true: * Cannot be used with gloves * Weather also * Picks up multiple inputs so cannot rest hand on screen * Requires special stylii * Fragile... Wrapup. The rest of this book will entirely assume capacitive touch, as that's the current winner by far. But in case you design for something else, or encounter additional technologies, here's a brief overview of the most important and commonly-encountered ones, and the most interesting future technologies. == Resistive Touch == Basics... List of upsides/downsides to it Simple guidelines for adapting touch info below to this. Pressure, so along axis of the end digit, not pads so much. All others apply. == IR??? == Mostly kiosks, dunno. Other old-school tech? At least mention things that are out of scope so people know what is not going to be covered. == Machine Vision == Already in use for general sensing... Do mention what we aren't talking about, how this is great for installations, all the way back to the original surface, and use the Argo example Mark Rolston showed off for room-size interactions. How it's awesome, but not what is in scope for this book so... Kinect and others... http://shoobe01.blogspot.com/2013/08/gesture-deathmatch-leap-motion-vs.html == Future Touch Technology == And current! Sensing contact patch so pressure, and whatever else seems good. ---- === References === * http://paulgraham.com/ecw.html?utm_content=bufferb0452&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer * https://en.wikipedia.org/wiki/Touchscreen