How Does Touch Screen Technology Work?

Touch screen is now a days much popular but it was started in 1971, as at that time first touch sensor was developed by Dr. Sam Hurst. But it was not a proper touch sensor. The first proper touch sensor was developed in the year 1974 and the name of the company was Elo touch systems. Three main components combine together to make an input they are touch sensor, controller and a software driver. Capacitive is the technology used in the modern touch items like iPhones. Resistive is another technology used in touch screens in this technology screen is made of many layers of electrically conductive material. In resistive technology when we physically press screen the layers comes in contact with each other. And these are the two most commonly used technologies in touch screens.

The sensor has some electrical current passing through it and by pressing the screen causes some fluctuation in that voltage. And this change in the voltage is the main thing in touch system that determines the place where our finger is pointing out on the screen. And the other thing is the controller but this is not used in mobile phones but used in monitors and touch monitors also require software or we can say that it needs a driver. Driver is an essential component in touch monitors. So the touch system, either in the mobiles or in the monitors make our work easier and reliable. We feel more easy in touching as compared to pressing the buttons.


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How Touch Screen Technology Works

Touch screen technology can be mysterious if you ever stop to wonder what really makes a screen recognize your finger, pen, or stylus. As technology advances, touch screens are becoming more popular because they make the user interface more exciting and intuitive for people new to modern tech gadgetry. There are three basic systems used in screens to recognize your touch and at the writing of this article, infrared technology is making its way as the fourth system as well as others in development for different scale products.

The first is a resistive system that uses a conductive and resistive metallic sheet to cover a glass panel. The two layers are held apart by spacers with electrical currents running through both layers when the screen is on. There is also a scratch protection layer that covers the metallic layer to keep the screen from being destroyed too easily. When the user touches the screen, the two layers are forced to touch each other at that spot. There is a change in the electrical field when the contact is made and the coordinates of the point of contact are fed to a computer which calculates where that is on the screen and in turn tells the operating system which determines what a touch on that particular spot means.

The capacitive system is built with a layer that holds an electrical charge right on top of the glass panel. When a finger touches the screen, some of the charge escapes into the finger. The decrease in charge is measured in circuits which are usually located at the corners of the screen. And from the relative change in charge at each corner the computer can calculate what the point of contact was with the finger that released some of the charge.

The surface acoustic wave system uses a pair of transducers along the sides of the glass plate. And reflectors are placed in the glass plate to reflect the electrical signal that is sent from one sending transducer to one receiving transducer. When a finger touches the screen, the electrical signal is disturbed and using two axes the computer can calculate the precise area of contact.

Because the surface acoustic system does not use a metallic plate, it allows 100 percent of light from the monitor through for perfect clarity. As opposed to the resistive system which transmits about 75 percent of the monitors light and the capacitive system which transmits about 90 percent for improved image quality over the resistive system.

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How Touch Screen Technology Helps


Have you ever wondered about touch screen computer monitors? I mean, how do they know where you are touching in the first place?

Today we find touch screen POS (points of sale) everywhere.

• Checkout stands in stores 
• Gas pump service stations 
• Fast food restaurant check stands

And that is just to name a few places where touch screen LCD monitors can be found today. I'm sure you can think of others.

No matter if it is a Samsung or Acer screen the mystery of how such devices recognize your finger, pen or stylus remains. Gone are the less intriguing days of dragging a mouse across the screen to complete your selection. Today's users are presented with a more interactive and interesting technical connection than ever before.

Currently, the three most common ways that these LCD monitors recognize your touch include:

1. Resistive 
2. Capacitive 
3. Acoustic

Though infrared technologies within are steadily finding their place within the industry.

How does the resistive approach work?

First, a conductive and resistive metallic sheer covers the glass panel so that both layers are separated by electrically charged spacers during operations. Both layers are forced to connect when the screen is touched thereby sending the proper message to the computers network of communications.

Comparatively, capacitive technology actually maintains an electrical charge on top of the glass panel. A touch screen LCD monitor using capacitive processes releases some of the charge into the user's finger. The lack of charge at that spot in the system is interpreted by the device as an entry which is then processed accordingly.

Finally, the surface acoustic wave system introduces transducers at the sides of the glass plate. Reflectors then use electrical signals to interpret what is being communicated by the user's actions.

Which touch screen computer best buy is right for you?

This largely depends on the purposes you have for such technology within your own projects. Whatever you decide, the bottom line is that today's technology within touch screen computer monitors is steadily moving forward.

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How Does Optical Touch Overlay Work?

Optical imaging.

Optical imaging is one of the latest sensor technologies used in touch screen interfaces. Optical imaging technology enables users to interact with the screen with a high degree of accuracy, clarity and convenience. Based on optical imaging technology, a wide range of products have come into being, such as the optical touch overlay, the optical touch module and the optical interactive white board.

Sensor design.

The optical imaging technology detects the touch point with optical sensors that operate on the basis of the principles of optics. An optical sensor is a device that converts light rays into electronic signals. It measures the physical quantity of light and translates it into a form read by the instrument. Optical sensors come with a lot of advantages, such as no contact pressure, no external interference, high-speed transmission of signal, capability of remote control, etc., and are widely used for detecting and tracking the motion of target object. Optical overlays use cameras, which detect specifically Infrared Light (IR).

Infrared Light Sources.

Infrared (IR) is a portion of the light spectrum with longer wavelengths than those of visible light and is radiated strongly by hot objects, so objects with heat are especially visible in infrared wavelengths of light. In optical touch devices, a filter that removes visible light is installed so that the camera sensor detects only infrared light. IR LEDs are used in most multi-touch optical equipment, as they are efficient and effective at providing infrared light.

Camera sensor.

Through camera sensor an optical image is converted into electronic signal and high-quality camera sensors ensure the good performance of the optical touch device. Firstly, a bandpass filter is required on the (IR sensitive) camera in order to prevent the visible light, adding to the touch's accuracy and responsiveness. Secondly, higher resolution of a camera with more pixels improves the optical touch's precision. Thirdly, higher frame rate means more snapshots and data in a short time, which make the touch screen more responsive. [1]

How it works.

An optical touch product uses an array of infrared (IR) LEDs in its bezel. When an object, or a finger, or a hand, approaches the screen, the IR light sources are interrupted. Two (or more) small-sized sensors then detect the interruption and track the movement of the approaching objects.

The heart of the technology is a controller that receives signals from the cameras, compensates for IR light distortions and locates the position of the touching object with extreme accuracy.

Besides compensation for distortions, a systematic algorithm is adapted to help eliminate the impact of ambient light to add to the accuracy of the optical touch screen.

Comparisons with other touch screen technologies.

Zero pressure

Optical imaging technology uses optical sensor to track the touch point, so the approaching object can be detected before it physically reaches the screen. This means zero or very little pressure is applied to the screen for a response.

Multi-touch capable

Optical touch products based on optical imaging technology can detect multiple touch points (fingers/pen/cards, etc) at the same time and allow users to use more than one object to point, rotate and stretch. Multi-touch goes beyond the capabilities of traditional touch screen devices, bringing a brand new touching and viewing experience to users.

Any substrate possible

Any substrate is suitable for the sensor, including glass, acrylic and polyester. Technologies such as capacitive and Surface Acoustic Wave (SAW) can only use glass with ITO (Indium Tin Oxide) coating for sensor substrate.

Designed for large displays

Optical imaging technology can be tapped into displays of very large sizes, while capacitive, resistive and SAW can hardly support devices over 30'. Optical imaging is consistent at all sizes, which makes purchase of large-scale optical touch equipment very cost-effective.

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This article is written solely by E. Yang



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Smartphones have become an integral part of modern life. With their reserves of information and apps to do anything you desire, they have become our beloved personal assistants. Initially, smartphones started out as humble mobile phones – devices that let you talk with a person on a similar device. Although humble, these were revolutionary, but it was only a matter of time before the world realized they had the potential to be so much more. With the advancement of technology, they were soon upgraded with better features and more usability.

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One of the revolutionary advancements was the major upgrade to the Input System. In the vast majority of modern phones, physical buttons have been replaced with touchscreens, which are far more efficient and practical. We already make use of touchscreens almost everywhere, aside from smartphones, such as in elevators, ATM machines, cash counters, etc.

downloadThe only problem is that we don’t understand much of what goes on behind that ‘black mirror’. Our knowledge about touchscreens isn’t any more developed than a toddler – we’re fascinated by them and rarely ask questions… until now.

There are basically two types of touchscreens:

Perimeter-Based Touchscreen

These touchscreens have emitters embedded in the phones that emit waves. The interference in the wave pattern is registered as an input. There is no need for actual contact in order to detect an input; even hovering works. The waves can be infrared light waves or ultrasonic sound waves, which are similar in concept, but differ in effectiveness and accuracy. The wave setup has no metallic layers on the screen, allowing for 100% light through output and perfect image clarity.

Overlay-Based Touchscreens

These touchscreens have sensors embedded under the glass layer, so actual contact with the screen is necessary for registering input. Overlay-based touchscreens are more popular because of their low cost and higher durability. There are two types of Overlay-based touchscreens that are used in your phones and other handheld devices.

Resistive Touchscreens

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Resistive Touchscreens

The resistive system works as a result of the interaction between two layers – the resistive layer and the conductive layer. The resistive layer is at the top, followed by the conductive layer, then the glass protector, and finally the display screen. The resistive layer is separated from the conductive layer by small spherical spacers. When you press the resistive layer, it actually bends and touches the conductive layer. The conductive layer then sends a current originating from this point of contact, while the processor in the phone uses this current to figure out the location of the point. Resistive screens are very durable and accurate, but not too efficient. These are used in places where accuracy is a priority over speed of use, such as in an ATM or cash-counter.

Capacitive Touch Screens

The capacitive system, on the other hand, does not have flexible screens, but instead utilizes the conductive nature of our skin. These touchscreens consist of a matrix of electrical circuits arranged on two similar, but perpendicular films that are thinner than a human hair. These layers have low-voltage current flowing through them, which gets transferred to our fingertips upon touch. The voltage drop due to this loss of charge is detected by four electrodes located at the four corners of your phone. Using the voltage drop data, the processor finds out the exact location of the input.

With the use of four electrodes and two conducting layers, unlike in resistive systems, it is possible to register slide input, as well as simultaneous multiple touches. The capacitive system transmits 90% of the light from the monitor, whereas the resistive system only transmits 75%. Due to this basic difference, capacitive surfaces reflect less ambient light, making it easier to see the screen.

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Ambient light reflection can make it difficult to read

Another area in which the systems differ is in what registers as a touch event. A resistive system registers a touch as long as the two layers make contact, which means that it doesn’t matter if you touch the screen with your finger or a rubber ball. A capacitive system, on the other hand, must have a conductive input, usually your finger, in order to successfully register a touch.

All of these touchscreen technologies can also be integrated on top of a non-touch-based system, like an ordinary LCD that is converted into an Open Frame Touch Monitor.

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Although this touchscreen technology was invented in the 1960s, high-end phones still use the basic concept developed back then. Some would say that we need an upgrade to newer tech.

Disney Research is currently developing a touchscreen technology called ‘TeslaTouch’. This aims to provide the user with hap-tic feedback and lets the touchscreen interact with the user. Voltage on the screen due to the conducting finger could be oscillated to control the friction between the screen and the finger. This could provide the user with the feeling of texture, or the user could find heavy files more difficult to drag than lighter ones! The future is going to be quite an amazing place!



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How Does a Touchscreen Actually Work?

Here's why your smartphone craves skin contact.

These days we don't think twice before tapping and swiping the ubiquitous touchscreens around us. For toddlers, it seems almost innate, and hey, even Teletubbies have touchscreens built into their blobby stomachs now. Chances are you tapped a link to access this article. But have you ever stopped to think about how a touchscreen actually works? We've got some answers.

Firstly, the touchscreen you use at the local ATM and the one on your smartphone are completely different types of technology. Screens that you tap at the ATM or the automated supermarket checkout are called 'resistive' touchscreens - they consist of two thin, flexible layers just barely spaced apart, with an electric current running in between. The actual LCD display of the device is located behind these layers.

When you press your finger on a resistive screen, the top, flexible layer touches the bottom one, and the interruption in the electrical current is noted by the device, and it calculates the precise location of the point of contact. Depending on what button is located under your finger, the software registers the coordinates and performs the command.

Resistive screens are a relatively cheap technology that's been around since the 1970s. Because they respond to pressure, you can activate them with bare fingers, gloves, or styluses (remember the PalmPilot?), but you can't swipe or use multi-touch gestures, because the electric current encased within can only successfully register one point of contact at a time. Additionally, the plastic used doesn't have the same clarity as glass, which is why ATMs and some in-flight entertainment screens have that characteristic haziness.

The glass-covered smartphone you carry in your pocket uses something different - it's called a 'capacitive' touchscreen. The name, unsurprisingly, comes from the term 'capacitor' - an electronic component that can temporarily store an electric charge (not to be confused with a flux capacitor). A capacitor is built out of two conductive layers separated by an insulator, and this principle is employed in making your iPhone respond.

If you hold your smartphone in bright sunlight at just the right angle, you may be able to notice a grid of dots underneath the glass surface. This is an array of horizontal and vertical transparent conductive wires that form capacitors at the crossings, with tiny electrical currents running through. These transparent wires are typically made out of indium tin oxide, and are located on the opposite sides of a sheet of glass, which acts as the insulator and is laminated to the top layer you touch.

Human skin conducts electricity, which is how a capacitive touchscreen responds - as you're writing a text, your finger decreases the charge at the intersection of the grid where the capacitor is located, and the microprocessor calculates which contact points were activated. This info is then relayed to the software, which in turn performs what you wanted - or, more likely, triggers yet another typo.

Unlike resistive touchscreens, capacitive touchscreens don't respond to pressure at all. Even though sometimes it feels like pressing harder did the trick, it's probably because squashing your finger on the glass increased the surface area of the touch, helping the processor register contact. If you have 'fat fingers' and touch too many areas of the screen at once, it gets confused and doesn’t respond at all. 

So a need for electrical conductivity is why you can't operate a smartphone with gloves or a plastic stylus, which are both essentially insulators. But as anyone who lives in a cold-enough climate can confirm, if you're in a pinch, swiping the screen with your nose will work just as well as a finger.



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How do touchscreens work?

What?

touchscreen1One of the driving forces behind science fiction is predicting technology of the future. Certain propositions like human teleportation and warp drive (traveling at speeds faster than light) have been deemed scientifically impossible, but others have been eerily accurate. One of the clearest examples of this is how touchscreen devices now not only exist, but are commonplace. Touchscreen technology was first developed for specialized research products in the 1970s, but now they are found in everyday devices, including cell phones, computer screens, and GPSs.

Why?

Touchscreens were never considered impossible, but when the idea of them was first conjured up, no one could have predicted how omnipresent they would become. They first started gaining momentum with the introduction of PDAs and certain handheld video game consoles, but it wasn’t until the iPhone was released in 2007 that touchscreens began to be used in nearly every new technology, revolutionizing the electronics market. What, then, was different about the iPhone that made it such a catalyst for future touchscreen technologies?

How?

Touchscreen technology prior to the iPhone used the “resistive” method. The idea behind the “resistive” method is quite simple: two thin layers, usually made of tough plastic, are spaced a miniscule distance apart with electricity running in between. The screen is above the upper layer and the LCD display is below the bottom layer. When the screen is pressed, it forces the top layer against the bottom layer so sensors can detect where the two meet. One of the best conveniences of this method is that it can detect touch from anything that presses down on the layers, whether it is a finger or a pen cap. However, this method can only recognize one point of contact because only one point can be fully depressed at a time and as a result, does not have smooth sliding and dragging motions (“Touchscreens”). Although this method is now considered largely outdated due to the mass market of iPhone technologies, it is still used on some ATMs and in-car screens.

touchscreen2On the other hand, iPhones, iPads, Samsung Galaxy smartphones, and Amazon’s Kindle Fire, to name a few, use the “capacitive” method. These electronic devices monitor changes in electrical currents running through the screens. The touchscreens include a layer of capacitive, or electricity-storing, material. The capacitors in the screen are arranged according to a coordinate system, creating a grid. The circuitry inside the screen can then sense changes in electrical charge at each point along the grid. As a result, every individual point on the grid generates its own signal when touched, which is then relayed back to the device’s processor, allowing the device to recognize multiple points of contact.

The downside to using this method as opposed to the resistive method is that capacitive screens function by sensing the electrical charges on your skin that are produced when your finger interacts with the electrical field. And so, a capacitive screen won’t work if the user is wearing gloves or if a stylus is being used (Wilson). Nonetheless, the capacitive method is much more responsive and versatile than the resistive method.

So?

This technology has evolved from phones to tablets to computers in the span of about five years and is still continuing to expand. One company has created a projector that can turn any surface into a touch screen, such as a desk, a wall, or even a human hand. Another company has developed a way to manipulate the electrical force between your finger and the screen to create textures on the glass. If touchscreen technology continues to develop further, it can be used in an infinite number of incredible ways, continuing on the path of transforming science fiction into scientific fact.