Resistive touchscreen

Touchscreen technology

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A resistive touchscreen is a type of touch-sensitive display that works by detecting pressure applied to the screen.[2] It is composed of two flexible sheets coated with a resistive material and separated by an air gap or microdots.[3]

Description and operation

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There are two different types of metallic layers. The first type is called matrix, in which striped electrodes on substrates such as glass or plastic face each other. The second type is called analogue which consists of transparent electrodes without any patterning facing each other. As of analogue offered lowered production costs.[citation needed] When contact is made to the surface of the touchscreen, the two sheets are pressed together. On these two sheets there are horizontal and vertical lines that, when pushed together, register the precise location of the touch. Because the touchscreen senses input from contact with nearly any object (finger, stylus/pen, palm) resistive touchscreens are a type of "passive" technology.

For example, during the operation of a four-wire touchscreen, a uniform, unidirectional voltage gradient is applied to the first sheet. When the two sheets are pressed together, the second sheet measures the voltage as distance along with the first sheet, providing the X coordinate. When this contact coordinate has been acquired, the voltage gradient is applied to the second sheet to ascertain the Y coordinate. These operations occur within a few milliseconds,[4][5] registering the exact touch location as contact is made, provided the screen has been properly calibrated for variations in resistivity.[6]

Resistive touchscreens can have high resolution ( x or higher), providing accurate touch control. Because the touchscreen responds to pressure on its surface, contact can be made with a finger or any other pointing device.[citation needed]

Comparison with other touchscreen technology

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Resistive touchscreen technology works well with almost any stylus-like object, and can also be operated with gloved fingers and bare fingers alike. In some circumstances, this is more desirable than a capacitive touchscreen, which needs a capacitive pointer, such as a bare finger (though some capacitive sensors can detect gloves and some gloves can work with all capacitive screens). A resistive touchscreen operated with a stylus will generally offer greater pointing precision than a capacitive touchscreen operated with a finger. Costs are relatively low when compared with active touchscreen technologies, but are also more prone to damage.[7] Resistive touchscreen technology can be made to support multi-touch input. Single-touch screens register multiple touch inputs in their balanced location and pressure levels.[8]

For people who must grip the active portion of the screen or must set their entire hand down on the screen, alternative touchscreen technologies are available, such as an active touchscreen in which only the stylus creates input and skin touches are rejected. However, newer touchscreen technologies allow the use of multi-touch without the aforementioned vectoring issues.[8]

Where conditions allow bare finger operation, the resistive screen's poorer responsiveness to light touches has caused it to generally be considered for use with low resolution screens and to lose market share to capacitive screens in the 21st century.[9] Projected capacitive touchscreen technology overtook resistive touchscreen technology in revenue in and in units in .[10]

See also

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References

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Through the mobile devices we use, touchscreens are literally putting the world at our fingertips morning, noon, and night. And it&#;s not just our personal devices that are all around us, touch screens are now prominent in busy high streets, airports, and industrial areas, but it wasn&#;t always so.

Here we&#;re going to take a brief look at the history of touchscreen technology.

The beginning

In E.A. Johnson invented, what is generally considered the first finger driven touchscreen. Published in Electronic Letters, Johnson&#;s article &#;Touch display &#; a novel input/output device for computers&#; outlined a type of touchscreen that many personal devices today use; capacitive touch.

Development

In the &#;s Dr Sam Hurst developed a new type of sensor called the &#;Elograph&#;. Discovered almost by accident, Hurst&#;s touch screen was not transparent, as most touchscreens are today. Using the force of a touch, the technology required a conductive layer to contact a separate layer below containing an X and Y axis, the coordinates were then transmitted to a computer. Today we refer to this type of touchscreen technology as &#;resistive&#; and is one of the most widely used touch variants. Later in , the first transparent resistive touchscreen was developed by Hurst and his team (the Elographics) and was patented in .

Further Development

In Nimish Mehta, at the University of Toronto developed a &#;touch tablet&#; device, using frosted glass, with a camera behind it that could recognise shadows and dark spots on the screen. This gestural interaction was then used by American computer Artist, Myron Krueger, to design an optical system that could track hand movements. Originally known as Video Place, it later became Video Desk in .

This system used projectors and video cameras to track hands, fingers, and the people they belonged to. However, unlike &#;true&#; multitouch technology, it wasn&#;t aware of who or what was touching it.

Early Adoption

Touchscreens began to become commercialised during the &#;s when HP (then known as Hewlett-Packard) created the HP-150. This computer featured a 9&#; CRT display, with infrared (IR) detectors around the edge that could detect when a user&#;s finger interacted with the screen, however there were noticeable issues with the system. The infrared technology was not very reliable and often a &#;touch&#; would block more than one sensor, and the system would not be able to tell where the real touch was occurring.

A real step forward came in when Bob Boie, of Bell Labs, created a new transparent touch overlay, by utilising a capacitive array over a CRT. This advancement led to the capacitive technology we see today in tablets and smartphones.

In , IBM and BellSouth launched the Simon Personal Communicator, one of the first cellphones with touchscreen technology. Advanced for its time, it featured paging capabilities, an , an appointment schedule, an address book, a calculator, and a resistive touchscreen operated with a stylus to navigate through menus and to input data.

Later that year Apple released the Newton PDA, with handwriting recognition. The software didn&#;t work very well, but undeterred, Apple continued to improve, and manufacture the Newton for a further 6 years.

Towards the end of the 90&#;s University of Delaware graduate student, Wayne Westerman published a doctoral dissertation entitled &#;Hand Tracking, Finger Identification, and Chordic Manipulation on a Multi-Touch Surface.&#; The paper detailed the mechanisms behind what we know today as multitouch capacitive technology. Westerman then formed a company called FingerWorks, and began manufacturing gesture-based products, including the iGesture pad; a PDA device that allowed one handed gesturing. FingerWorks was eventually bought by Apple in , and the technology became widely available in their phones and music players in .

Innovation

The mass adoption of projected capacitive (or p-cap) touch technology by smartphones and tablets, has created a greater demand for large format, commercial applications such as; digital signage, industrial and point of sale (POS), to become interactive, and here&#;s where the technology has really come into its own.

Scaling up p-cap touch sensors to close to 100&#; diameter is not an easy task, meaning that we&#;ve had to innovate, creating new manufacturing techniques, and advanced controller electronics, to offer the same responsiveness consumers expect from their hand-held interactive device.

Having been developing and manufacturing p-cap touch sensors for over 20 years we have become rather good at it, first with the introduction of ZyTouch®; a &#;hot-laminated&#;, and initially single-touch solution, which remains the toughest, and most durable touchscreen on the market. Over the next decade we developed our proprietary &#;cold-lamination&#; manufacturing technique, allowing the development of touch sensors made from a single glass substrate (ZyBrid®), which thanks to Zytronic&#;s 50+ years of glass processing knowhow, is tough, durable and totally customisable (even in ones and twos). During the same period, our talented R&D team were hard at work advancing our touch controller technology to accompany the unique touch sensors, and in we introduced our first multi-touch controller and sensor, which offered the same durable and customisable options as standard ZyBrid, but with true multitouch capabilities (up to 40 simultaneous touch points).

Never standing still, we&#;ve continued to invest in and advance our proprietary touch technology, and this month  released the all-new ZXY500 multi touch controller based on our own design ASIC (not a 3rd party solution) &#; fully optimised to our patented touch sensing technology. This innovative new range of control electronics allows touch screens to be designed with ultra-narrow inactive borders and even facilitate the integration of contact-less peripheral systems such as NFC payment, and charging alongside the touch sensors.

For additional information about our new ZXY500 controller range, see the data sheet, and our FaB&#;s .

Contact us if you&#;d like to find out more, or discus any new touch applications.

Want more information on High-End Industrial Control Resistive Touch Screens? Feel free to contact us.