Touch screen: resistive or capacitive - what's the difference? Touchscreen - what is it? Using and calibrating the touchscreen for your phone or tablet

The structure of the touch screen (touchscreen) and problems associated with its replacement

Touch screen- an information input and output device, which is a screen that responds to touches.

Resistive touch screen

A resistive touch screen consists of a glass panel and a flexible plastic membrane. A resistive coating is applied to both the panel and the membrane. The space between the glass and the membrane is filled with micro-insulators, which are evenly distributed over the active area of the screen and reliably isolate conductive surfaces. When the screen is pressed, the panel and membrane are closed, and the controller, using an analog-to-digital converter, registers the change in resistance and converts it into touch coordinates (X and Y).

In general terms, the reading algorithm is as follows:
1. A voltage of +5V is applied to the upper electrode, the lower one is grounded. The left and right are short-circuited and the voltage on them is checked. This voltage corresponds to the Y-coordinate of the screen.
2. Similarly, +5V and ground are applied to the left and right electrodes, and the X-coordinate is read from the top and bottom.

Capacitive touch screens

A capacitive (or surface capacitive) screen takes advantage of the fact that a large capacitance object conducts alternating current.

A capacitive touch screen is a glass panel coated with a transparent resistive material (usually an alloy of indium oxide and tin oxide). Electrodes located at the corners of the screen apply a small alternating voltage (the same for all corners) to the conductive layer. When you touch the screen with your finger or other conductive object, current leaks. Moreover, the closer the finger is to the electrode, the lower the screen resistance, which means the greater the current. The current in all four corners is recorded by sensors and transmitted to the controller, which calculates the coordinates of the touch point.

In earlier models of capacitive screens, direct current was used - this simplified the design, but if the user had poor contact with the ground, it led to failures.
Capacitive touchscreens are reliable, about 200 million clicks (about 6 and a half years of clicks every second), do not leak liquids, and tolerate non-conductive contaminants very well. Transparency at 90%. However, the conductive coating is still vulnerable. Therefore, capacitive screens are widely used in machines installed in protected areas. They do not respond to a gloved hand.

Multi-touch(English multi-touch) is a function of touch input systems that simultaneously determines the coordinates of two or more touch points. Multitouch can be used, for example, to zoom an image: as the distance between the touch points increases, the image enlarges. In addition, multi-touch screens allow multiple users to work with the device simultaneously. They are often used to implement other, simpler functions of touch displays, such as single touch or quasi multi-touch.
Multitouch allows you to not only determine the relative position of several touch points at any given time, it determines a pair of coordinates for each touch point, regardless of their position relative to each other and the boundaries of the touch panel. Correct recognition of all touch points increases the capabilities of the touch input system interface. The range of tasks solved when using the multi-touch function depends on the speed, efficiency and intuitiveness of its use.

The most common multi-touch gestures

Move your fingers - smaller
Spread your fingers - get bigger
Move multiple fingers - scroll
Two Finger Rotate - Rotate an object/image/video

Resistive Touch Screen Installation Issues

Sometimes a complete analogue of the required wheelbarrow is not at hand, or the pinout of the cable is different, the following problems may arise:
1.Touch rotated 90.270 degrees
- Swap X-Y

2.The touchpad is turned horizontally
- Swap X+ , X-

3. Turn the touch upside down
- Swap Y+, Y-

These solutions need to be implemented if the problem does not go away after calibrating the touch screen.

Replacing the touch screen did not help.
- Reflash the phone

Resistance at TOUCHSCREEN contacts
Y-,Y+=550 Om Without pressing
X-,X+=350 Om Without pressing

Y+,X+=from 0.5 to 1.35 kOm Measurements were taken in different corners of the touchscreen when pressed. Without touching the touchscreen, the resistance is infinity.
Y-, X- = from 1.35 to 0.5 kOm Measurements were taken in different corners of the touchscreen when pressed. Without touching the touchscreen, the resistance is infinity.

Resistance may vary depending on touch screen model. These measurements were taken on the touch screen from the I9+++ phone.

When is it time to replace your touchscreen?

It's time to replace the touch screen in the following cases:
- if he does not respond to touch
- you found an “oily stain” on it (multi-colored stains)
- it is impossible to calibrate the touch screen
- after entering the message and selecting the English text input mode, try to put dots over the entire area, if lines appear instead of dots, then it’s time to change
- after entering the service-miscellaneous-Touch Screen, try to put dots over the entire area; if green stripes appear instead of crosses, it’s time to change
- if you try to click on an icon, desktops flip through or icons fall off (vertical shedding of icons in iPhone-like phones)
- if 5 minutes after calibration you again do not hit the icon you click on

Just recently, few could believe that phones with familiar buttons would give way to devices that were controlled by touching the screen. But times are changing and the demand for push-button phones is gradually falling, while the demand for smartphones is growing.

The term “touchscreen” is formed from two words - Touch and Screen, which in English translates as “touch screen”. Yes, that's right - a touchscreen is a touchscreen that you touch when you use your smartphone or tablet. In fact, touch screens are found not only in the world of mobile technology. So, you could see them when depositing funds into your mobile device account through a terminal, at an ATM, in ticket devices, etc.

Touch-screen owes its appearance to Western scientists. The very first samples were born in the second half of the 60s of the last century. Based on this, we can conclude that the touchscreen has been in use for more than 40 years. Before smartphones, they were used in ATMs, etc. At the moment, every person who uses cellular communications, car navigators, visits banks and shops, encounters this technology, sometimes without even knowing what it is called. So, we figured out what a touchscreen is in phones. Essentially, this is the same as a finger touch display. It is perfectly used instead of a keyboard and is actively used in mobile technologies. The advantages of a touchscreen include protection from dust, moisture and other adverse environmental factors, as well as a high degree of reliability. If our touch device does not always respond to touch, or even refuses to do so, for example, it does not want to change the brightness on the iPad, most likely it is the touch-screen that has failed. It is relatively inexpensive (especially if we are interested in a resistive display), and it is easy to replace.

Touchscreen basis

The basis of any touchscreen is a liquid crystal matrix, which is actually a smaller copy of the one found in the monitor. On the back side there are backlight diodes, and on the front side there are a number of layers that record pressing (resistive screen) or touch (capacitive screen).

A person who is well versed in what a touchscreen is understands that most of the devices manufactured use a resistive touchscreen. This follows from their low cost and relative simplicity of design. Many Chinese “smartphones” that have flooded the market have a resistive type of screen, the manufacturing technology of which, by the way, appeared earlier than capacitive.

Types of touch screens

Touch screens are divided into resistive, matrix, projected capacitive, surface acoustic wave touch screens, infrared, optical, strain gauge, DST and induction touch screens.

Resistive touch screens

They are divided into four-wire and five-wire.

The resistive screen sensor consists of two transparent plastic plates with a thin conductive mesh that are located on the surface of a conventional liquid crystal screen. Between the plates there is a transparent dielectric layer. The program displays a graphical interactive interface, which, thanks to the transparent materials on the matrix, is clearly visible. When responding to a program request, the user clicks on the desired interface point (for example, the image of a button). - The plastic dielectric diverges, the plastic plates come into contact, supplying current from the electrode of one to the grid of the other. The appearance of current is recorded by the recording controller, which, in accordance with the coordinate grid, will determine the pressing point. The coordinates of the point are entered into the program and processed according to the established algorithms.

Four-wire screen

A resistive touch screen consists of a glass panel and a flexible plastic membrane. A resistive coating is applied to both the panel and the membrane. The space between the glass and the membrane is filled with micro-insulators, which are evenly distributed over the active area of the screen and reliably isolate conductive surfaces. When the screen is pressed, the panel and membrane are closed, and the controller, using an analog-to-digital converter, registers the change in resistance and converts it into touch coordinates (X and Y). In general terms, the reading algorithm is as follows:

A voltage of +5V is applied to the upper electrode, and the lower one is grounded. The left and right are short-circuited, and the voltage on them is checked. This voltage corresponds to the Y-coordinate of the screen.

Similarly, +5V and ground are supplied to the left and right electrodes, and the X-coordinate is read from the top and bottom.

There are also eight-wire touch screens. They improve tracking accuracy, but do not improve reliability.

Five-wire screen

The five-wire screen is more reliable due to the fact that the resistive coating on the membrane is replaced by a conductive one (the 5-wire screen continues to work even with a cut through membrane). The rear glass has a resistive coating with four electrodes at the corners.

Initially, all four electrodes are grounded, and the membrane is “pulled up” by a resistor to +5V. The voltage level on the membrane is constantly monitored by an analog-to-digital converter. When nothing is touching the touch screen, the voltage is 5V.

As soon as the screen is pressed, the microprocessor detects the change in membrane voltage and begins to calculate the coordinates of the touch as follows:

A voltage of +5V is applied to the two right electrodes, the left ones are grounded. The voltage on the screen corresponds to the X-coordinate.

The Y-coordinate is read by connecting both upper electrodes to +5V and to ground both lower ones.

Resistive touch screens are cheap and resistant to contamination. Resistive screens respond to touch with any smooth, hard object: a hand (bare or gloved), a stylus, a credit card, a pick. They are used wherever vandalism and low temperatures are possible: for automation of industrial processes, in medicine, in the service sector (POS terminals), in personal electronics (PDA). The best samples provide an accuracy of 4096x4096 pixels.

The disadvantages of resistive screens are low light transmission (no more than 85% for 5-wire models and even lower for 4-wire models), low durability (no more than 35 million clicks per point) and insufficient resistance to vandalism (the film is easy to cut).

Matrix touch screens

The design is similar to resistive, but simplified to the limit. Horizontal conductors are applied to the glass, and vertical conductors are applied to the membrane.

When you touch the screen, the conductors touch. The controller determines which conductors are shorted and transmits the corresponding coordinates to the microprocessor.

They have very low accuracy. Interface elements have to be specially positioned taking into account the cells of the matrix screen. The only advantage is simplicity, cheapness and unpretentiousness. Typically matrix screens are queried row by row (similar to a button matrix); this allows you to set up multi-touch. They are gradually being replaced by resistive ones.

Capacitive touch screens

A capacitive (or surface capacitive) screen takes advantage of the fact that a large capacitance object conducts alternating current.

In earlier models of capacitive screens, direct current was used - this simplified the design, but if the user had poor contact with the ground, it led to failures.

Capacitive touch screens are reliable, about 200 million clicks (about 6 and a half years of clicks with an interval of one second), do not leak liquids and tolerate non-conductive contaminants very well. Transparency at 90%. However, the conductive coating located directly on the outer surface is still vulnerable. Therefore, capacitive screens are widely used in machines only installed in a weather-protected room. They do not respond to a gloved hand.

It is worth noting that due to differences in terminology, surface- and projected-capacitive screens are often confused. According to the classification used in this article, the screen of, for example, the iPhone is projected capacitive, not capacitive.

Projected capacitive touch screens

A grid of electrodes is applied on the inside of the screen. The electrode together with the human body forms a capacitor; the electronics measures the capacitance of this capacitor (supplies a current pulse and measures the voltage).

Samsung has managed to install sensitive electrodes directly between the subpixels of the AMOLED screen, which simplifies the design and increases transparency.

The transparency of such screens is up to 90%, the temperature range is extremely wide. Very durable (the bottleneck is the complex electronics that process clicks). PESE can use glass up to 18 mm thick, which results in extreme vandal resistance. They do not react to non-conductive contaminants; conductive ones are easily suppressed using software methods. Therefore, projected capacitive touch screens are widely used in personal electronics and in vending machines, including those installed on the street. Many varieties support multi-touch.

Surface acoustic wave touch screens

The screen is a glass panel with piezoelectric transducers (PETs) located in the corners. At the edges of the panel there are reflective and receiving sensors. The operating principle of such a screen is as follows. A special controller generates a high-frequency electrical signal and sends it to the probe. The probe converts this signal into a surfactant, and the reflective sensors reflect it accordingly.

These reflected waves are received by the corresponding sensors and sent to the probe. The probes, in turn, receive the reflected waves and convert them into an electrical signal, which is then analyzed using a controller. When you touch the screen with your finger, some of the energy from the acoustic waves is absorbed. The receivers record this change, and the microcontroller calculates the position of the touch point. Reacts to touch with an object capable of absorbing the wave (finger, gloved hand, porous rubber).

The main advantage of a surface acoustic wave (SAW) screen is the ability to track not only the coordinates of a point, but also the pressing force (here, rather, the ability to accurately determine the radius or area of pressing), due to the fact that the degree of absorption of acoustic waves depends on the pressure at the point touch (the screen does not bend under finger pressure and is not deformed, so the pressing force does not entail qualitative changes in the controller’s processing of data on the coordinates of the impact, which records only the area that overlaps the path of acoustic impulses).

This device has very high transparency because the light from the imaging device passes through glass that does not contain resistive or conductive coatings. In some cases, glass is not used at all to combat glare, and emitters, receivers and reflectors are attached directly to the screen of the display device. Despite the complexity of the design, these screens are quite durable. According to, for example, the American company Tyco Electronics and the Taiwanese company GeneralTouch, they can withstand up to 50 million touches at one point, which exceeds the life of a 5-wire resistive screen.

Surfactant screens are used mainly in slot machines, secure information systems and educational institutions. As a rule, surfactant screens are divided into regular ones - 3 mm thick, and vandal-resistant ones - 6 mm. The latter can withstand a blow from the fist of an average man or a drop of a metal ball weighing 0.5 kg from a height of 1.3 meters (according to Elo Touch Systems). The market offers options for connecting to a computer both via the RS232 interface and via the USB interface. At the moment, controllers for surfactant touch screens that support both types of connection - combo (data from Elo Touch Systems) are more popular.

The main disadvantage of a surfactant screen is malfunctions in the presence of vibration or when exposed to acoustic noise, as well as when the screen is dirty. Any foreign object placed on the screen (for example, chewing gum) completely blocks its operation. In addition, this technology requires contact with an object that necessarily absorbs acoustic waves - that is, for example, a plastic bank card is not applicable in this case.

The accuracy of these screens is higher than matrix ones, but lower than traditional capacitive ones. As a rule, they are not used for drawing and entering text.

Infrared touch screens

The principle of operation of the infrared touch panel is simple - the grid formed by horizontal and vertical infrared rays is interrupted when any object touches the monitor. The controller determines the location where the beam was interrupted.

Infrared touch screens are sensitive to contamination and are therefore used where image quality is important, for example, in e-books. Due to its simplicity and maintainability, the scheme is popular with the military. Intercom keypads are often made using this principle. This type of screen is used in numerous Neonode phones.

Optical touch screens

The glass panel is equipped with infrared illumination. At the glass-air interface, total internal reflection is obtained; at the glass-foreign object interface, light is scattered. All that remains is to capture the scattering picture; for this there are two technologies:

In projection screens, a camera is placed next to the projector.

This is how Microsoft PixelSense works, for example.

Or the additional fourth subpixel of the LCD screen is made photosensitive.

They allow you to distinguish hand presses from presses with any objects, there is a multi-touch. Large touch surfaces are possible, up to a blackboard.

Strain gauge touch screens

React to screen deformation. The accuracy of strain gauge screens is low, but they are highly resistant to vandalism. The main application is ATMs, ticket machines and other devices located on the street.

DST touch screens

The DST (Dispersive Signal Technology) touch screen detects the piezoelectric effect in the glass. It is possible to press the screen with your hand or any object.

A distinctive feature is the high reaction speed and the ability to work in conditions of heavily soiled screens. However, the finger must move; the system does not notice a stationary finger.

A universal type of touch screen has not yet been developed, and the technologies currently used have both their advantages and disadvantages. Read about the pros and cons of the main types of touch screens in this material.

The use of touch screens is most appropriate in small portable devices. Firstly, this is due to the inconvenience of using a mouse, keyboard and other input devices in phones and other small electronics. Secondly, eliminating hardware buttons allows you to significantly increase the screen area. Thirdly, the production of touch panels is expensive, and their use in large screens is still at least economically unprofitable.

However, having started with such small devices as PDAs, touch screens have already reached the medium format (tablets and some laptops), and it is only a matter of time before they appear on the big screen.

There are only a few types of touch screens. Below we will discuss the three most common technologies, as well as several of its varieties.

RESISTIVE PANELS

The touch part of such screens consists of two layers separated by a small space, each of which has an array of resistive or conductive elements (depending on the specific implementation).

When you press with a finger, stylus (or any other object) on the surface of the screen, these layers come into contact, the elements close, and the screen “understands” where it was touched.

Considering that contact between the two layers is only possible using a flexible material that will bend under pressure, resistive screens are usually covered with a special flexible film rather than glass. This leads to scratches and more frequent damage to the screen when applying excessive pressure with the stylus.

The technology is one of the simplest, so it was the first to appear in touch devices. It still has some advantages, but there are more disadvantages than other types of touch screens.

Advantages

In addition to the low price (the cost of such displays is approximately half that of capacitive ones), the accuracy of resistive screens also depends little on the condition of the top layer, so if it gets dirty or wet, the responsiveness of the sensor practically does not change.

Despite the age of the technology, it still allows us to make the most accurate touch panels. In a properly calibrated display, you can actually hit a specific pixel with the stylus thanks to a dense lattice of resistive elements.

Flaws

Despite the fact that there are exceptions to this rule, most resistive screens do not recognize multi-touch, that is, the screen understands only one touch (the very first or the strongest), which significantly limits the ability to control the interface. Even in devices where multi-touch is implemented, fewer simultaneous touches are still recognized than in the most common capacitive screens.

Using multiple layers reduces the contrast and brightness of the screen. The light transmission coefficient is ~75%, which is ~15% lower than in capacitive screens. Thus, in devices with a resistive sensor, the contents of the screen are more difficult to view in direct sunlight or under strong artificial lighting.

The use of two layers separated by a small gap is an indirect reason for reducing the accuracy of the sensor. If you hold the stylus perpendicular to the screen, then the accuracy may be the same, but at an angle, the discrepancy will be several pixels due to the fact that the point on which the stylus presses is not directly above the desired pixel (parallax effect).

Protection against accidental input in resistive screens is a certain pressure that must be overcome in order for the device to count the command. Consequently, it is more difficult to equip resistive screens with an additional protective coating, which will only increase the response threshold. Paired with a plastic coating, which is necessary for the flexibility of the touch layer, resistive screens are more susceptible to damage than others, especially scratches, and if handled incorrectly (pressing hard with a sharp object), they can simply crack.

Despite the fact that the number of clicks at each specific point is estimated at 30 million, resistive screens still fail earlier than other types and are the most unreliable by this indicator.

Conclusion

Low cost and resistance to contamination (or rather, maintaining input accuracy when contaminated), coupled with all of the above disadvantages, have become the reason that resistive screens are slowly being forced out of use, although they have been able to gain a foothold in some niches, for example, in the sector of terminals for fast payment.

Styluses

A characteristic feature of devices with a resistive sensor is the widespread use of a stylus, the contact area of which with the surface is smaller than that of a finger, and the pressure force is greater, which results in more accurate input.

The presence of a stylus is desirable, although not necessary for screens with a small diagonal (mainly phones, and a few years ago, PDAs), however, in tablets, sufficient accuracy can be achieved using your fingers.

After PDAs were completely replaced by smartphones and other devices several years ago, it seemed that styluses had left the scene along with them forever, but now you can increasingly see their reincarnation, especially in devices of intermediate sizes between smartphones and tablets.

Since resistive screens are used less and less now, styluses have also changed a bit. Adapting to modern realities, they began to be produced with special attachments at the end, which are recognized by capacitive screens.

CAPACITIVE PANELS

The principle of operation of capacitive screens is that a small voltage is applied to a special layer of electrical conductor located on the outer surface of the screen, forming a uniform electrostatic field. When a finger, which is a conductor of electricity, is applied to the screen, the properties of the field change due to the appearance of a leak (the user acts as a ground electrode and “steals” current from the screen). By changing the capacitance, you can determine the presence of a contact and its coordinates.

To determine the coordinates, electrodes are installed in the corners of the screen that measure the strength of the leakage current, and the stronger it is on each specific sensor, the closer the pressing occurred. By defining specific values, you can very accurately calculate the coordinates of the click.

A subclass of capacitive screens are projection-capacitive screens, the operating principle of which is also to measure capacitance, but the basic elements in them are located not on the outside of the screen, but on the inside, which increases the security of the sensor. These are the screens that are now used everywhere in smartphones.

Unlike resistive panels, which use a flexible material, capacitive sensors are covered with glass. This better protects them from scratches, although they are more likely to cause cracks if subjected to a strong impact or fall.

Advantages

The absence of multiple layers of additional materials not only increases the brightness of the screen (transparency to light is approximately 90%), but also reduces the distance between the screen surface and the image, allowing you to more accurately hit the desired pixels. Even if the gain is not big, it is still noticeable, especially when the device is at a certain angle relative to the axis of view, that is, at those moments when the difference between the actual position of the desired pixel on the screen and the point at which you need to hit shift as much as possible relative to each other friend.

Samsung's Super AMOLED displays further reduce screen thickness by eliminating the additional layer of capacitive elements. In this type of screen they are built directly into the matrix.

Capacitive screens are much more durable than resistive screens (almost by an order of magnitude) when it comes to the number of clicks before the touch elements fail. The number of such repetitions is estimated at 200+ million times.

Flaws

Capacitive screens are more expensive to manufacture than resistive screens and require that the material touching their surface must have the properties of a conductor. Therefore, it will not be possible to use any convenient object or work with ordinary gloves with capacitive screens. In this regard, special capacitive styluses and gloves for working with touch panels in cold weather are becoming widespread.

The accuracy of capacitive screens is somewhat lower than that of resistive screens, although in practical tasks this difference is not very noticeable, since it is literally 1-3 pixels, and given that in most cases the program interface is already designed to eliminate these errors, it is difficult to call this a disadvantage .

Conclusion

Capacitive panels, in terms of their characteristics and price, are best suited for mobile device screens, which is why they now dominate this sector.

INFRARED PANELS

Despite the fact that infrared sensors began to appear in devices later than other types of panels, they should not be considered more advanced. They have several advantages, however, most likely, like resistive screens, they will remain niche and will not be able to displace capacitive panels.

Optical

The main difference between infrared sensors and all others is that special sensors are located not on the surface of the screen, but along the edges of it and form a series of horizontal and vertical infrared rays directly above the display. When an object touches the screen, the rays are broken and thus the location of contact is determined.

Thermal

A type of infrared screens are screens with thermal sensors. In order for them to respond to touch, the object must be warm.

Like capacitive panels, devices with infrared sensors use a protective glass coating, which causes the same advantages and disadvantages: better scratch resistance, but more likely to crack if hit hard.

Advantages

The location of the sensors on the sides of the matrix makes it possible to eliminate the intermediate layer on the LCD matrix, which improves the brightness of the picture (the transparency of the coating is almost 100%), reduces the gap between the real image and the screen surface, makes the display more resistant to damage, and also allows you to work with contaminated screen, but provided that contamination does not interfere with the free propagation of infrared rays.

Infrared (optical) screens can be operated with gloves or using any other convenient objects.

Flaws

Any contamination at the edges of the matrix, obscuring infrared signal sources, leads to malfunctions of the sensors. Problems also arise with slight curvature of the device, when the rays leave a plane parallel to the screen.

However, one of the most common problems with infrared sensors is false alarms. Since users do not have to physically touch the screen, sometimes the sensors are activated when the finger is sufficiently close to the screen or while it moves from one point to another.

Despite the fact that infrared sensors are often used in devices with a relatively low cost (for example, e-readers), screens with an infrared sensor themselves are more expensive than both resistive and capacitive screens.

Conclusion

If resistive and capacitive screens could be conditionally classified as respectively dying out and dominant types of screens, then infrared sensors are a marginal device technology, since they are used in little-known models of portable electronics. The exception is e-readers, such as the Nook Touch.

INSTEAD OF AN EPILOGUE

Touch and conventional displays will see many more innovations in the near future (flexible matrix, new protective coatings), but when it comes to technologies responsible for input recognition, there are no revolutionary alternatives on the horizon, so capacitive sensors will continue to dominate. as the most convenient and relatively inexpensive compared to other types of sensors.

There is constant debate about which phone has the better screen. Especially between owners of Apple equipment and those who prefer devices on the Android platform.

This simple infographic beautifully breaks down all the benefits of each type of touchscreen. I hope that when buying your next smartphone, it will help you make the right choice and not overpay a tidy sum.

So, there are three types of touch screens: Resistive, Capacitive and Infrared.

Resistive

Phones with resistive screens: Samsung Messager Touch, Samsung Instinct, HTC Touch Diamond, LG Dare

How do they work? Small dots separate several layers of material that transmit current. When the upper flexible layer presses on the lower layer, the electric current changes and the location of the impact, that is, the touch, is calculated.

How much does it cost to manufacture? The cost of manufacturing resistive touch screens is not very high - $ .

Screen material. A layer of flexible material (usually a polyester film) is placed on top of the glass.

Tools of influence. Fingers, gloved fingers or stylus.

Visibility on the street. Poor visibility in sunny weather.

Possibility of multi-gestures. No.

Durability. For its price, the screen lasts quite a long time. Easily scratched and susceptible to other minor damage. It wears out quite quickly and requires replacement.

Capacitive

Phones with capacitive touch screens: Huawei Ascend, Sanyo Zio, iPhone, HTC Hero, DROID Eris, Palm Pre, Blackberry Storm.

How do they work? The current is broadcast from the corners of the screen. When a finger touches the screen, it changes the direction of the current and thus the location of the touch is calculated.

How much does it cost to manufacture? Quite expensive - $$ .

Screen material. Glass.

Tools of influence. Only fingers without gloves.

Visibility on the street. Visibility on a sunny day is good.

Possibility of multi-gestures. Eat.

Durability.

Infrared

Phones with infrared touch screens: Samsung U600 (heat), Neonode N2 (optical).

How do they work? In order for the heat-sensitive screen to react, you need to touch it with a warm object. An optical screen uses a grid of invisible sensors directly above the screen. The touch point is calculated based on the point where the x-y axis was violated.

How much does it cost to manufacture? Very expensive - $$$ .

Screen material. Glass.

Tools of influence. Optical - fingers, gloves and stylus. Heat-sensitive - warm fingers without gloves.

Visibility on the street. Visibility in sunny weather is good, but strong sunlight affects productivity and accuracy.

Possibility of multi-gestures. Yes.

Durability. Lasts quite a long time. Glass breaks only from serious damage.

Tablets, many smartphones, as well as monitors and displays on household appliances are equipped with touch screens. This technology pleases, firstly, with its attractive design, and secondly, with its functionality and simplicity. In addition, now there is no need to waste space on placing buttons, which is also very convenient. Read about the types of screens, their structure, operating principles, pros and cons in our article.

The most popular types of sensors

Resistive sensors

The resistive sensor consists of a plastic membrane (the first layer) and a panel made of glass (the second layer). A micro-insulator is laid between these layers, designed to protect conductive surfaces from each other. Electrodes are located on the surfaces of the layers (in the first layer they run horizontally, in the second – vertically). By pressing on the screen, you provoke the closure of the layers; a special sensor reads your press and converts it into a signal that is transmitted to the processor. As a result, the screen reacts to the task set by your touch - for example, it starts a video, opens a document, etc.

This technology is considered quite simple, and therefore not too much money is spent on the production of resistive screens. As a result, products with them often end up in the budget price segment, which is the main advantage of equipment with resistive screens. Equipment with resistive displays is presented in large quantities and assortment. Among the disadvantages of this type of sensors are the lack of support for multi-gestures, poor visibility in the sun/in bright light, low wear resistance, and low accuracy.

Capacitive sensors

This technology is more advanced - it supports multi-touch, has decent visibility in bright light, better wear resistance, and a higher level of accuracy. Disadvantages include the higher price of devices with capacitive screens and a negative reaction to exposure to liquids.

How does this type of touch screen work? The key role here is played by electrodes located in the corners of the display and transmitting alternating flows of electricity to each other. As a result, a kind of current grid is formed. By pressing on the screen, a person shifts the direction of the current, which allows the system to determine the location of the press and accordingly calculate and execute the required command. In this case, the human body, together with the screen itself, act as current conductors. The display consists of glass coated with a resistive material that provides effective electrical contact.

Infrared sensors

The screen frame (made of glass) includes receivers and emitters of infrared rays. When working, they form an infrared grid on the surface of the display. By clicking on the screen, we will block access to certain rays - the system will calculate this location and calculate the corresponding task that it will need to perform.

Disadvantages include not very high accuracy (especially in bright light), “fear” of contamination and the high cost of products with infrared displays. Among the advantages are good visibility in the sun and durability.

Less popular types of sensors

Matrix sensors

The matrix system is similar to how the sensor works in resistive display models. Only vertical current conductors are applied to the membrane, and horizontal current conductors are applied to the glass. Pressing causes a closure, which the system calculates and then converts into performing a particular task.

Matrix screens are rarely used today because they are considered very inaccurate and therefore unproductive.

Surface acoustic wave screens

Piezoelectric transducers are built into different corners of the glass panel. Along the perimeter of the display there are sensors that receive and reflect signals. A special controller provides high frequency signal generation. Pressing the display initiates the execution of a task.