Page 22
www.us-tech.com
December, 2020
Don’t Take Touch for Granted: Criteria for Choosing the Right Sensor Control IC
T
ouch has become an incredibly intuitive way for people to interact with high-tech devices. Only a few short years after the first smart-
phones hit the shelves, it seems the whole world is happily tapping, swiping, pinching and flicking at home, at work and on the road. We expect every re- sponse to be precise and instantaneous — as cool and glassy smooth as the surface of the device itself.
Design Factors Designers know that this is not always easy
to achieve. The processes involved with creating and measuring the capacitance changes that de- scribe the type and location of each touch on the screen are subject to numerous challenges. These include electrical noise both inside and outside the system, humidity in the environment and uninten- tional user gestures close to the screen. In addition, ensuring electromagnetic compat-
ibility (EMC) of the end product is especially chal- lenging for equipment that contains a touchscreen. Passing EMC testing calls for immunity to external electrical disturbances, while the touchscreen relies on detecting and measuring these disturbances to interpret the user’s commands. Achieving great touch sensitivity and fast response, while prevent- ing unwanted signals causing spurious responses calls for careful engineering. Unfortunately, after many cumulative man-
years of touchscreen development experience, there is no “default setting,” no universal parame- ters that can be simply programmed to make the touchscreen of an embedded project just work.
Dedicated Ti tanium Selective Solder Nozzle
By Adilson Jacob, Application and Development Engineer, Anders Electronics plc Every system is different. First, there are
multiple touchscreen technologies, such as glass-
most projects consider the touch display before the controller. The concept for the product is often pre- dominantly about look and feel, and the display size is often determined by application constraints, as are decisions about the coverlens, including the
Achieving great touch sensitivity
and fast response, which depends on slight changes in capacitance across the screen, while preventing
unwanted electromagnetic signals, is a delicate balance.
A well-designed touchscreen can often be the most intuitive way to interact with high-tech equipment.
film or glass-glass construction with single or dou- ble ITO (SITO/DITO) layers. Also, the size of the screen and the coverlens material and thickness influence touch response. Designers may have on- ly a limited notion of the environment in which the screen will be used — whether outdoors or indoors, whether there will be high humidity or likelihood of water splashes, or other potential sources of in- terference. The interactions between the display and the
touch controller are critical to ensuring a great touch experience for the user. It is fair to say that
Adjustable SMT Machining Services Ful l Process Carrier
thickness, glass or polycarbonate, any vandal-re- sistant treatments, and anti-glare/anti-reflective coating.
Choosing a Touch Controller With so many decisions already made or diffi-
cult to change, the challenge to identify and inte- grate a suitable touch controller — and optimize the firmware — requires special skills and expert- ise.
Typical touch control chips on the market to-
day are microcontroller-based ICs that integrate circuitry needed to stimulate the sensor and cap- ture measurable responses. This typically includes a high-voltage charge pump controller, regulator, and multichannel capacitance-to-digital converter that takes care of driving and sensing the capaci-
Continued on next page
Manual Sl ide Line (Combo-Slide)
Wet ted Selective Solder Nozzles
PCB Assembly and Handling Solutions
Custom Selective Solder Fixture
Assembly Fixture (Flip-Rak)
1 Gwinnup Road • Blairstown, NJ 07825 Phone: 908.362.5588 • Fax: 908.362.5115
cs@mb-mfg.com •
WWW.MB-MFG.COM
Adjustable Wave Solder Fixture
Ti tanium Finger Masks Board St i f feners
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80
