The struggle of screens – capacitive versus resistive. Your phone's touchscreen: resistive, capacitive or projected capacitive

In modern mobile devices- smartphones, communicators, players - two types of touch screens are used: resistive and capacitive. Moreover, more than 90% of all touch displays today they are of the resistive type, although there is already a clear tendency to increase the share of capacitive screens.

To stop getting confused, just remember: resistive screens are pressure sensitive, while capacitive screens are touch sensitive. This difference is due to the design of the displays, and it is in principle impossible to train, for example, a capacitive screen to recognize pencil presses.

Resistive screen It is a glass liquid crystal display on which a flexible membrane is applied. A resistive composition is applied to the contacting sides, and the space between the planes is divided by a dielectric. Electrodes (usually four or five) are attached to the edges of the plates. When pressed, the screen and the membrane come into contact at the point of pressing, which allows you to “find out” where the pressing occurred. That is why The resistive screen can be pressed with any hard object- from a fingernail and a stylus to a pencil or a match, and it will work. Their second advantage is resistance to pollution.. This means that even the screen surface covered with dust and water stains will still work well, and pressure sensitivity will not change.

If speak about disadvantages of resistive touch screens, then the first one can be called its low durability. If you translate the lifespan of such a screen into the number of clicks, it would be 1 million clicks for four-wire screens and 35 million clicks for five-wire screens (the two most common types of resistive touch screens). The disadvantages of resistive screens also include low light transmission - no more than 70-85%, which requires increased backlight brightness. Despite the used protective layer, the operation of such a screen can be quite easily disrupted by damaging it. Plastic is easily cut by sharp objects, and its surface does not withstand too much high temperatures and may melt.

The popularity of resistive touch screens is still very high. They are the ones who did touch phones accessible and allowed us to bring to the market many inexpensive devices costing up to $200. Among the most popular devices in this segment are the Samsung GT-S5230 Star, Nokia 5230 and others.

Capacitive touch screen works based on the human body's ability to conduct electricity. Most often, a capacitive screen is based on a glass substrate, on the surface of which a resistive material is applied, covered with a conductive film. When you touch the screen with your finger, an electric current is generated, and a special controller calculates the coordinates of the touch.

In terms of accuracy in determining coordinates, capacitive screens are in no way inferior to resistive screens, but they transmit light better (90% or more instead of 80%). The durability of such screens is much higher - they can withstand up to 200 million clicks. Impact environment to capacitive screens less - ideally, they are able to work flawlessly in sultry heat and extreme cold. But, as practice shows, at best, the accuracy of determining coordinates decreases; at worst, it simply stops responding.

The main disadvantage of this type of screen is that it can only operate under the influence of a conductive object. That is, if you want to use a regular stylus or any other hard object, the screen will not react to your touch.

This problem manifests itself especially strongly in winter, when on a frosty day, when answering an important call, there is no opportunity (or desire) to take off the glove and press the corresponding button on the screen. True, some owners of such phones have already found a rather original way out of this situation - instead of using their fingers to press this button, they use... their nose! It must be said that in some cases it is possible to control it with a gloved hand - this will depend on the quality of the screen and its sensitivity, as well as the material from which the glove is made.

Another disadvantage of capacitive touchscreens is their high susceptibility to surface contamination. In this case, the sensitivity and accuracy of clicks can be significantly reduced.

Projected capacitive touch screens They differ from classic capacitive screens in only one way - they support Multitouch technology. Projected capacitive touch screens have many advantages - in addition to Multitouch support, they are durable (about 200 million touches), resistant to damage (can be used for protective purposes). strained glass or special plastic up to 18 mm thick), can withstand work at very low temperatures (down to -40 °C), and are capable of transmitting light well (over 90%). Projected capacitive screens have only one drawback - they can only be controlled using conductive objects (as is the case with conventional capacitive screens).

The most famous smartphones with projected capacitive screens are produced by Apple company, she also became a pioneer in this field. Also working Multitouch is available on models such as Nokia N8, Samsung GT-I9100 Galaxy S II, HTC Desire S.

What to choose

If you are faced with the question of choosing a mobile device depending on the type of touch screen, you can first decide how much you are willing to spend on buying a phone or smartphone, what the operating conditions of the device will be, and whether you agree to use only your fingers for control. If you're willing to pay a hefty price for Multitouch support and need a modern, high-performance smartphone, choose a model with a projected capacitive display. If you are purchasing a phone with a touch screen for the first time and want to save money, a resistive screen will suit you. He will be the best solution, if you are embarrassed by the need to operate it exclusively with your fingers, or if you often work in less than sterile conditions, and particles of dirt and dust regularly fall on the surface of the screen.

Resistive or capacitive screen? Resistive! October 26th, 2014

How do capacitive screens used in the iPhone and other modern mobile devices differ from other types of touch displays? And is this the future?

You need to choose a RESISTIVE SCREEN!

Review and explanation

I have been convinced many times that regular users absolutely do not suspect the existence different types touch screens and learn with genuine amazement that the lack of response of the display of a newly purchased communicator to the usual poking with a pencil is not at all a sign of a malfunction. It's just a different screen, built on a different technology. Even some sellers are confused in the readings, attributing to displays of one type the properties of others. So first we will conduct brief educational program, after which you will be able to distinguish different types of screens literally by touch. And then we’ll talk about which of them is the future.

Modern mobile devices - smartphones, communicators, players - use two types of touch screens: resistive and capacitive. Moreover, more than 90% of all touch screens today are of the resistive type, although there is already a clear trend toward an increase in the share of capacitive screens.

To stop getting confused, just remember: resistive screens are pressure sensitive, while capacitive screens are touch sensitive. This difference is due to the design of the displays, and it is in principle impossible to train, for example, a capacitive screen to recognize pencil presses.

A resistive screen is a glass liquid crystal display on which a flexible membrane is applied. A resistive composition is applied to the contacting sides, and the space between the planes is divided by a dielectric. Electrodes (four or eight, five or six and seven) are attached to the edges of the plates. It is easy to guess that when pressed, the screen and the membrane come into contact at the point of pressing, the coordinates of which are calculated by sequentially applying current to the upper and lower plates and measuring the voltage at the point of contact of the plates. That is why you can press such a screen with any hard object - from a fingernail and a stylus to a pencil or a match, and it will work.

Operating principle of a five-wire resistive screen

Due to their design, resistive screens and, especially, their conductive layer are subject to gradual wear, which is why there is a need for periodic calibration of the screen. The simplest and cheapest four-electrode screens can withstand only 3 million clicks on one point. Several times more reliable - up to 35 million clicks - are five-wire ones, where four electrodes are located on the screen plate, and the fifth is on a membrane coated with a conductive composition and serves only as a kind of “probe”. In addition, five-wire and its modifications 6 and 7-wire screens continue to work even if part of the membrane is damaged.

The disadvantages of resistive screens also include low light transmission - no more than 70-85%, which requires increased backlight brightness. But these screens are extremely cheap to produce, which explains their wide distribution.

A capacitive touch screen is generally a glass panel on which a layer of transparent resistive material is applied. Electrodes are installed at the corners of the panel, supplying low-voltage power to the conductive layer. AC voltage. Since the human body is capable of conducting electrical current and has some capacitance, when touching the screen, a leak appears in the system. The location of this leak, that is, the point of contact, is determined by a simple controller based on data from the electrodes at the corners of the panel.

Operating principle of a capacitive screen

There are no flexible membranes on the screen, which ensures high reliability and allows you to reduce the brightness of the backlight. Unfortunately, you cannot poke them with a stylus or fingernail, since the command simply will not be recognized. Only with your finger. Such a screen also does not like negative temperatures: at best, the accuracy of determining coordinates decreases; at worst, it simply stops responding.

Operating principle of a projected capacitive screen

Unfortunately, on the simplest capacitive screen, which is now installed in the cheapest “touch” phones, it is impossible to organize a fashionable “multi-finger” multi-touch interface - four electrodes in the corners are capable of recording only one click at a time. Projected capacitive displays, in which reverse side the screen has a whole grid of conductors (or rows of electrodes), to which a weak current is applied, and the place of contact is determined by the points with increased capacity. By the way, such screens are capable of reacting even to the approach of a hand (and therefore to a gloved hand) - it all depends on the sensitivity settings.

Many experts, not without reason, believe that resistive screens are a thing of the past, and capacitive screens are the future. Indeed, just the transition from a mechanical-electrical input system to a purely electrical one is certainly progress. Reliability and accuracy of coordinate determination have increased, the need for calibration has disappeared, and a “multi-finger” interface has appeared.

The abandonment of resistive displays stimulated the development of truly convenient user interfaces, optimized for finger control. In modern communicators, you no longer need to aim a sliver at microscopic interface elements inherited from the “big ones” operating systems. Please note, the latest Windows Phone 7 is absolutely nothing like the rest of the family of “mobile windows” of previous generations, in which there was nothing to do without a tiny stylus.

Skeptics will note that you can no longer draw on a capacitive screen with a regular plastic stylus or some random object, or write down a memo by hand. To do this, you will have to buy a special stylus with an electrical capacity. HTC even patented such a capacitive stylus (http://www.devicewire.co.uk/official-htc-hd2-capacitive-stylus) and asks about $30 for it. But how often do we draw on our phones or use handwriting? As they say in certain circles, a little less often than never. But touch tablets for drawing use completely different technologies, and they are not going anywhere.

The only reason why resistive screens still occupy the lion's share of the market is because they are extremely cheap. In addition, over the course of several years, all the largest vendors managed to produce such a number of very diverse and not at all cheap handsets with resistive displays that it would be like death for them to immediately write them into the category of obsolete. In any case, there will be more and more devices with capacitive screens, and fewer and fewer devices with resistive screens. In a few years, we won’t even remember that we once poked special thin slivers into the screen of smartphones.

ANALYSIS AND CONCLUSION

Analyzing the operating principle of the two different screens, we can conclude that in resistive the screen has no effect on the human body electromagnetic radiation and indirectly by electric shock. Conversely, the screen capacitive this is practically an electromagnetic field into which you immerse your hand to perform certain actions. Moreover, this electromagnetic field begins to be physically felt already from a distance of 5-10 cm from the screen.

Do not forget that blood in the human body is carried by hemoglobin, which contains iron. Using capacitive screen, you actually conduct electromagnetic treatment of your blood, which then distributes these results throughout the body.

A rheumatist, as a person most sensitive to effects on the cardiovascular system, will immediately answer: “After five minutes from the capacitive screen, my hand hurts and my bones ache! Throw away this shit immediately! Don’t give it to children!”

If you work a lot and often with touch screens, then always choose a resistive one. In principle, children should not be given access to capacitive screens. We don't need multitouch if such crap accompanies its use. Improve resistive screens to multi-touch and don’t come to us with capacitive screens.

Analysis and conclusion: Judicial technical expertise institutions of CNEAT Samara:

Or a smartphone, a person reads a lot of reviews and reviews, while he simply gets lost in the abundance of new and incomprehensible terms. For example, such a user may have a question: resistive screen - what is it? There is no need to prove that the main part of a tablet is the display. That is why it is worth understanding such a difficult concept.

This term hides a display that is produced using the technology of the same name. Thanks to this, it is possible to ensure its special properties in comparison with the second common type - a capacitive screen. It is worth understanding in more detail what this technology is, as well as what it means for specific user. To simplify, then in general outline thanks to such features, it is possible to turn a stylus or nail into something like computer mouse. The sensor includes two layers: glass and a special plastic membrane. An insulator layer is located between them. The deflection of the membrane to the glass, that is, the contact of these two layers, leads to a change in the level of resistance, which is recorded by the device itself, due to which the point of impact of the stylus is determined.

If we consider what a resistive screen is, then it is worth determining how all this is expressed in practice, since in theory it may seem very strange. That is why it is worth considering the features of such technology in comparison with capacitive technology in order to understand what its advantages and disadvantages are. Among the primary advantages of such screens is their low cost. This technology is quite simple and well-tested, thanks to which it is possible to create quite budget models phones, tablets and e-readers. This device is very reliable, since the glass used is quite strong. If the gadget is equipped with a new generation sensor - a five-wire screen, then it will be especially reliable, since it is not afraid of even single breaks or cuts in the outer membrane.

If we consider the resistive screen type, it is worth noting that it also has certain disadvantages. It is generally accepted that devices using such screens transmit less contrast and brighter images. Such devices do not allow multi-touch, that is, the use of some complex movements, for example, spreading your fingers to zoom in - a resistive screen will not allow this.

What this is, you understand in general terms. Now it should be said that the user who chooses this or that gadget already has a good idea of ​​what exactly he needs, because he can touch the screen with his hands, and here he does not need to master any abstract concepts such as processor power or version of the operating system.

It is important to note that you should not dismiss this type of device just because its price is lower. IN in this case cheaper does not mean worse, it just means that you won’t have to overpay for features that you personally don’t need. Now you understand what a resistive screen means.

What is the difference capacitive screens, used in iPhone and other modern mobile devices, from other types of touch displays? And is this the future?

I have repeatedly been convinced that ordinary users are completely unaware of the existence of different types of touch screens and are truly surprised to learn that the lack of response of the display of a freshly purchased communicator to the usual poking with a pencil is not at all a sign of a malfunction. It's just a different screen, built on a different technology. Even some sellers are confused in the readings, attributing to displays of one type the properties of others. So first we will conduct a brief educational program, after which you will be able to distinguish different types of screens literally by touch. And then we’ll talk about which of them is the future.

Modern mobile devices - smartphones, communicators, players - use two types of touch screens: resistive And capacitive. Moreover, more than 90% of all touch screens today are of the resistive type, although there is already a clear trend toward an increase in the share of capacitive screens.

To stop getting confused, just remember: Resistive screens are pressure sensitive, while capacitive screens are touch sensitive. This difference is due to the design of the displays, and it is in principle impossible to train, for example, a capacitive screen to recognize pencil presses.

A resistive screen is a glass liquid crystal display on which a flexible membrane is applied. A resistive composition is applied to the contacting sides, and the space between the planes is divided by a dielectric. Electrodes (four or eight, five or six and seven) are attached to the edges of the plates. It is easy to guess that when pressed, the screen and the membrane come into contact at the point of pressing, the coordinates of which are calculated by sequentially applying current to the upper and lower plates and measuring the voltage at the point of contact of the plates. That is why you can press such a screen with any hard object - from a fingernail and a stylus to a pencil or a match, and it will work.

Due to their design, resistive screens and, especially, their conductive layer are subject to gradual wear, which is why there is a need for periodic calibration of the screen. The simplest and cheapest four-electrode screens can withstand only 3 million clicks on one point. Several times more reliable - up to 35 million clicks - are five-wire ones, where four electrodes are located on the screen plate, and the fifth is on a membrane coated with a conductive composition and serves only as a kind of “probe”. In addition, five-wire and its modifications 6 and 7-wire screens continue to work even if part of the membrane is damaged.

The disadvantages of resistive screens also include low light transmission - no more than 70-85%, which requires increased backlight brightness. But these screens are extremely cheap to produce, which explains their wide distribution.

A capacitive touch screen is generally a glass panel on which a layer of transparent resistive material is applied. Electrodes are installed at the corners of the panel, supplying low-voltage alternating voltage to the conductive layer. Since the human body is capable of conducting electrical current and has some capacitance, when touching the screen, a leak appears in the system. The location of this leak, that is, the point of contact, is determined by a simple controller based on data from the electrodes at the corners of the panel.

There are no flexible membranes on the screen, which ensures high reliability and allows you to reduce the brightness of the backlight. Unfortunately, you cannot poke them with a stylus or fingernail, since the command simply will not be recognized. Only with your finger. Such a screen also does not like negative temperatures: at best, the accuracy of determining coordinates decreases; at worst, it simply stops responding.

Unfortunately, on the simplest capacitive screen, which is now installed in the cheapest “touch” phones, it is impossible to organize a fashionable “multi-finger” multi-touch interface - four electrodes in the corners are capable of recording only one click at a time. Projected-capacitive displays are free from this drawback, in which a whole grid of conductors (or rows of electrodes) is applied to the back of the screen, to which a weak current is supplied, and the point of contact is determined by points with increased capacitance. By the way, such screens are capable of reacting even to the approach of a hand (and therefore to a gloved hand) - it all depends on the sensitivity settings.

Many experts, not without reason, believe that resistive screens are a thing of the past, and capacitive screens are the future. Indeed, just the transition from a mechanical-electrical input system to a purely electrical one is certainly progress. Reliability and accuracy of coordinate determination have increased, the need for calibration has disappeared, and a “multi-finger” interface has appeared.

The move away from resistive displays has spurred the development of truly seamless user interfaces optimized for finger control. In modern communicators, you no longer need to aim a sliver at microscopic interface elements inherited from “large” operating systems. Note, latest Windows Phone 7 is absolutely nothing like the rest of the family of “mobile windows” of previous generations, in which there was nothing to do without a tiny stylus.

Skeptics will note that you can no longer draw on a capacitive screen with a regular plastic stylus or some random object, or write down a memo by hand. To do this, you will have to buy a special stylus with an electrical capacity. HTC even patented such a capacitive stylus and asks about $30 for it. But how often do we draw on our phones or use handwriting? As they say in certain circles, a little less often than never. But touch tablets for drawing use completely different technologies, and they are not going anywhere.

The only reason why resistive screens still occupy the lion's share of the market is because they are extremely cheap. In addition, over the course of several years, all the largest vendors managed to produce such a number of very diverse and not at all cheap handsets with resistive displays that it would be like death for them to immediately write them into the category of obsolete. In any case, there will be more and more devices with capacitive screens, and fewer and fewer devices with resistive screens. In a few years, we won’t even remember that we once poked special thin slivers into the screen of smartphones.

Nowadays you won’t surprise anyone with a touch screen. Moreover, it is already strange to see devices without a sensor, especially when we're talking about O mobile gadgets. This is due to the desire to increase the working surface area. But how often do we think about what type of display is used in a particular device? Has it ever happened that, having bought new tablet or a smartphone, we try to control it using the usual digital pen, but bad luck, the device simply does not respond to its touch. Apparently, the screen is made using a different technology, capacitive, which is gradually beginning to displace its predecessor, the resistive type display.

Can be found a large number of touch displays, differing not only design features, but also the principle of operation. Today, there are the following types of touch screens: resistive, capacitive, projection-capacitive, matrix, surface acoustic wave touch screen, infrared, strain gauge, inductive.

IN currently There are two main types of touch screens used in electronics: resistive and capacitive. We will talk about them in more detail, and also try to highlight the strong and weak sides everyone.

First, let's look at the operating principle of a resistive touch screen. It consists of a glass panel and a flexible plastic membrane, on which a resistive coating is applied. The space between the glass and the membrane is filled with micro-insulators, which in turn reliably insulate the conductive surfaces, evenly distributed over the active area of ​​the screen. When you press the display, the panel and membrane close, and the controller, using an analog-to-digital converter, registers the change in resistance, converting it into touch coordinates. It is for this reason that such a screen can be pressed with any hard object, it can be a fingernail, a special stylus, or even an ordinary pencil. As a consequence of this structure, resistive screens gradually wear out, which is why there is a need for periodic calibration of the screen so that when you press the display, the coordinates of the touch point are correctly processed.

There are four-, eight-, five-, six- or seven-electrode screens. The simplest to manufacture, and therefore the cheapest, are four-electrode ones. They can withstand only 3 million clicks at one point. Five-wire ones will already be much more reliable - up to 35 million clicks; in them, four electrodes are located on the panel, and the fifth is located on a membrane, which is coated with a conductive composition. It is worth noting that five-wire and subsequent versions of six- and seven-wire screens continue to work even if part of the membrane is damaged.

Advantages

The advantages of a resistive screen include the low cost of its production, and, consequently, the low cost of the device in which it is used. In addition, it is worth noting that the sensor response here does not depend on the condition of the screen surface; even if dirty, the touchscreen remains just as sensitive. It should also highlight the accuracy of hitting desired point, because a dense lattice of resistive elements is used.

Flaws

As a disadvantage of resistive screens, we highlight low light transmission, no more than 70% or 85%, so increased backlight brightness is required. It is also low sensitivity, i.e. Simply touching with your finger is not enough, pressure is required, so you cannot do without a digital pen or long nails. This type in most cases it does not support multi-touch, i.e. the screen only understands one touch. When interacting with the screen, you need to make some effort to transmit any command, and if you overdo it, you can not only scratch it, but also damage the display. As mentioned above, for proper functioning it is necessary to periodically calibrate the screen.

Capacitive touch screen

A capacitive screen is a glass panel that is coated with a transparent resistive material, typically an alloy of indium oxide and tin oxide. Electrodes are installed at the corners of the panel, supplying a low-voltage alternating voltage to the conductive layer; they monitor the flow of charges in the screen and transmit data to the controller, thus determining the coordinates of the touch point. Before touching, the screen has some electric charge; when touched with a finger, a point appears on the conductive layer, the potential of which is less than the potentials of the electrode, since the human body has the ability to conduct electric current and has a certain capacity. There are no flexible membranes on the screen, which ensures high reliability and allows you to reduce the brightness of the backlight. This type of screen is capable of simultaneously determining the coordinates of two or more touch points, which means multi-touch support.

Projection-capacitive screens have become a subtype of capacitive screens. They work on a similar principle. The difference is that the basic elements in them are located not on the outside of the screen, but on the inside, making the sensor more protected. This type of display is mainly used in modern mobile devices.

Interaction with a capacitive screen should only be carried out with a conductive object, a bare finger or a special stylus that has electrical capacitance. The number of clicks before the sensor elements fail reaches more than 200 million times.

Advantages

One of the advantages of capacitive screens is that even in bright sunshine, visibility remains quite good, which cannot be said about a resistive screen, since it reflects a lot of ambient light. Another advantage was the ability to quickly and accurately recognize a touch without using additional accessories. The undoubted advantage of screens of this type is more long time sensor service compared to the previous type. A “multi-finger” interface or multi-touch has also appeared, although not all devices with a screen of this type are fully implemented.

Flaws

TO negative aspects The use of a capacitive touch screen can be attributed to a higher cost due to the complexity of production. Interaction with the display is only possible by touching a material that is a conductor. For this reason, special capacitive styluses or gloves are purchased to work with it; this becomes especially important in cold weather, and this is another expense item.

To summarize, let us recall that resistive screens are pressure sensitive, while capacitive screens are touch sensitive. The accuracy of capacitive displays is comparable to that of resistive displays, but capacitive type is characterized by higher reliability due to the absence of a flexible membrane, and a smaller number of layers makes them more transparent.

There is an opinion that resistive displays have already outlived their usefulness, and the future belongs to capacitive displays. Indeed, the transition from mechanical-electrical input to electrical already means a lot, since the accuracy of determining coordinates has increased, and multi-touch has appeared.

However, today on the market electronic technology There are still a large number of devices with resistive screens, but they are slowly beginning to be replaced by gadgets with capacitive sensors. Observing this trend, one can assume that the former will soon disappear altogether.