The difference among Resistive, Capacitive, SAW and IR touch panels

Resistive touch screen technology is recommended for use in POS (Point of Sale): Grocery Stores, Hotels, Restaurants and Retail Stores; Industrial Applications: MMI (Man Machine Interface), Machine and Process Control; Portable Devices; Personal Information Management Systems; Transportation Solutions; Medical Solutions: Equipment, Instrumentation and Patient Monitoring Systems. Resistive technology generally uses a display overlay composed of layers, each with a conductive coating on the interior surface. Special separator "dots" are distributed evenly across the active area and separate the conductive interior layers. The pressure from using either a mechanical stylus or finger produces an internal electrical contact at the "action point" which supplies the controller with vertical and horizontal analog voltages for data input. To reduce parallax for older "curved" CRT applications only, resistive touchscreens are generally spherical to match the curvature of the CRT (true flat resistive touch overlays are also available for TFT flat panels and/or CRTs). Our resistive touchscreens are anti-glare to reduce reflective shine intensity, which will slightly diffuse the light output throughout the screen. Resistive technology offers tremendous versatility in that activation can be initiated by; a gloved hand, fingernail, mechanical stylus or an ungloved finger. Resistive touch screens can be gasket sealed for NEMA 4 and NEMA 4X environments. Limitations include: Low light output, diffused resolution images and the a plastic surface material can be scratched if improperly touched.

Capacitive touch screen technology is recommended for use within KIOSK applications that require a "finger touch". It will not operate with either a gloved hand or with a mechanical stylus. It is made of glass, which makes it extremely durable and scratch resistant. This glass overlay has a coating that stores the charge deposited over its surface electrically. Capacitive touchscreens operate using oscillator circuits that are located in each corner of the glass overlay and measure the capacitance of the area being "touched". Depending on where the person touches the overlay, the oscillators will vary in frequency. Then a touchscreen controller measures the frequency variations to ascertain the coordinates of the person's touch. When used with flat panel displays, capacitive offers drift-free stable performance that is not susceptible to deterioration over time. A capacitive touch screen is impervious to grease, dirt and water, which makes it ideal for frequent use. It can also be gasket sealed for NEMA 4 and NEMA 4X operation. Since a capacitive touchscreen is made of glass, it is susceptible to breakage.

SAW touch screen technology is suggested for use in ATMs, Amusement Parks, Banking and Financial Applications, Gaming Environments, Industrial Control Rooms and KIOSK. SAW touch cannot be used within NEMA environments, as the technology cannot be gasket sealed. It has excellent durability that allows it to continue working if scratched since the overlay for the touch sensor is a solid glass display. The disadvantage to this glass overlay is that is breakable and won't work in washdown conditions. The waves are spread across the screen by bouncing off reflector arrays along the edges of the overlay and are detected by two "receivers". The acoustic wave weakens when the user touches the glass with their finger, gloved hand or soft stylus. The coordinates are then determined by the controller circuitry that measures the time at which the amplitude declines. It is the only technology that can produce a Z-coordinate axis response. SAW technology offers drift-free stable performance that is always precise. SAW offers superior image clarity, resolution and high light transmission.

Infrared touch screen technology is based on "legacy" technology. Over the years, Infrared bezels have proven to be a very reliable technology for use in ATMs, Food Service and Preparation, KIOSK, Medical Instrumentation, Process Control Systems and Transportation Tracking applications. It does not incorporate any sort of "overlay" that could inhibit screen clarity or brightness, but instead, uses a special bezel of LEDs (light emitting diodes) along with diametrically opposing phototransistor detectors, which surround the glass of the display surface. The controller circuitry scans the screen with an invisible lattice of infra-red light beams just in front of the surface that directs a sequence of pulses to the LED's. It then detects information at the location where the LEDs have become interrupted by a stylus or finger. The infrared frame housing the transmitters can impose design constraints on operator interface products. IR screens are sealable to IP65 and operate flawlessly in conditions from severe weather to factory environments where water, acid, oil, dust, dirt and moisture can be a problem. A few limitations are (1) that they usually require low-resolution output of the monitor, (2) can produce activation without touching the screen and (3) the cost to produce the special Infrared bezel is quite high.

	Resestive	Capacitive	SAW	Infrared
Benefits
Vandal Resistant
Scratch Resistant
Abrasion Resistant
Not Sensitive to Dust
Not Sensitive to Humidity
Not Sensitive to Water Droplets
Not Sensitive to Moisture
Not Sensitive to Temperature
Not Sensitive to Cleaning Chemicals
Not Sensitive to RFI
Not Sensitive to EMI
Can be Hermetically Sealed
Can be FINGER operated
Can be STYLUS operated			Soft Only
Can be GLOVED HAND operated
Has Tactile Sence
U.S. Federal 508 Applications
Recommended Applicatons
Restaurant POS
Hospitality
Kiosks	Supervised
Medical
Gaming
Process Conrol - Automation
Food Preparation
Avionics
ATM Machines
Pay Phones
Military Applications
Harsh Environments
Sinocan Monitor Types and TouchScreen Cross Reference
Desktop LCD
Open Frame LCD
NEMA 4/4x/12
Rack Mount
Bezel Frame
Chassis LCD

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The difference in characteristic between 4 wire T/P and 5 wire T/P

	4 wire T/P	5 wire T/P
Noise	Voltage switches between top and bottom layers that is easy to cause interference.	The signal of X axis and Y axis are all at the same layer that the interference is not easy to occur.
Cutting	The linear is defective once damaged	Still can work perfectly even is cut
Lifetime of single point	Above one million	Above ten million
Life time	Good	Excellent
Stability	Common	High
Price	Low	Medium
Technical level	Low	High

4 Wires Touch Kit:
The preferred solution for low cost applications. The coordinate X axis of the touch point can be detected by measuring the voltage value thru the top ITO layer and the coordinate Y axis of the touch point can be detected in the same way by changing voltage input to the top layer's electrodes.

5 Wires Touch Kit:
The preferred solution for applications requiring durability and reliability over time.
Similar to the 4-Wire technology, 5-Wire touch screen also consists of a conductive bottom layer (ITO Glass or ITO Film) and a conductive top layer (ITO Film). The fundamental structure difference between the two is: in the 5-wire technology, all the electrodes are placed on the bottom layer and the top layer acts only as a voltage measuring probe. Therefore, the touch screen works properly even with damages or scratches on the top layer.

8 Wires Touch Kit:
8-Wire Resistive Touch Screen: the touch screen controller can automatically correct the drift issue resulted from the harsh environment exposure or long time usage, so is the preferred solution for applications requiring accuracy and no re-calibration over time.
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