difference between tft lcd and resistive touchscreen made in china

Capacitive touch panels are the more modern and advanced touchscreen option because of their advanced capabilities. They are commonly found in consumer products like smartphones, tablets, appliances, and monitors.

A capacitive touchscreen detects and responds to changes in capacitance caused by the screen"s electrostatic field when the screen"s surface is touched.

Capacitive touchscreen displays allow for touch gestures and respond to multi-touch inputs. You’ll typically be able to enter one to five touch inputs simultaneously, but some capacitive touchscreens can process even more.

Capacitive touchscreens deliver brighter, higher contrast images due to the makeup of their panels. Displays with capacitive touch screens are more durable than resistive touch screens because they are designed with cover glass on their top layer. In fact, all of our capacitive TFT displays have standard 0.7mm thick built-in cover glass and can be further

While the cost is currently higher than resistive touchscreens, capacitive touchscreens are quickly becoming the industry standard in touchscreen technology.

The enhanced responsiveness can be a downside depending on how and where the display is used. For example, a capacitive touchscreen would not easily respond to the user while wearing certain types of gloves. Although capacitive touchscreens don’t respond to inorganic inputs, they can still be accidentally activated by other conductive elements. One of the the most common elements that causes interruptions is water.

Rain, humidity, and condensation on the surface of capacitive touchscreens will often cause accidental inputs and reduced accuracy until the water is removed. This is one of the main reasons why a resistive touchscreen would be chosen over a capacitive touchscreen in certain situations.

Any device that utilizes touch gestures like swiping, pinching, or multi-touch will require a capacitive touchscreen. These features often help make capacitive touchscreen displays more intuitive and user-friendly than resistive touchscreens. Capacitive touchscreens are best suited for applications requiring improved touch responsiveness with better image brightness and contrast.

sense pressure on the display"s top layer and send a signal to the circuit layer to activate the touchscreen functionality. Because they use pressure to activate the touch inputs, resistive touchscreen displays can be used with a stylus, gloves, and other items. Resistive touchscreens are built without cover glass and made of plastic, making them more susceptible to dents and scratches.

"touch event" occurs when these two layers make contact with each other (closing the circuit) by the user"s action of pressing into the soft, semi-flexible top layer. Each layer consists of horizontal and vertical lines (x,y matrix) that detects the exact location of the touch.

The gap or space layer typically consists of air or inert gas and some spacers whose only purpose is to separate the soft top layer from the bottom layer.

Resistive touchscreens are often seen as the less advanced variety of touch panel compared to capacitive touch panels. However, being able to interact with non-organic inputs keeps these touchscreens relevant in specific industries.

Resistive touchscreen displays are less sensitive than capacitive touchscreen displays. This is considered an advantage in some cases and is why they’re chosen for specific applications. Resistive touchscreens will not respond to accidental inputs from the environment, so they won’t be interrupted by things like water spills or lightweight debris landing on the screen.

This type of touchscreen requires more intentional inputs from the user, making them more reliable in rugged and unstable environments. For example, a resistive touchscreen is the perfect solution on a construction site where water or debris might land on the screen. They’re also the best touchscreen display option for situations where the user is wearing gloves.

Resistive touchscreen panels are unfortunately more susceptible to dents and scratches. Their poor visibility in direct sunlight does not make them ideal for outdoor applications. Their inability to respond to multi-touch inputs can be a disadvantage in fast-paced applications requiring such. Because resistive touchscreens rely on the pressure applied to the top layer, they tend to be abused and mishandled, which makes them less durable over time than capacitive touchscreens.

Resistive touchscreen technology is ideal for low-cost applications involving rugged environments, indirect sunlight, and simple touch features. Fewer accidental touch inputs, better resistance to heat and moisture, and the ability to be operated with pretty much anything (stylus, pen, gloves, fingers, etc.) make this touchscreen technology a more reliable solution when user input is crucial.

While it’s clear that capacitive touchscreens are dominating the consumer electronics market, resistive touchscreens still have an advantage in some ways.

If you’re looking for a cost-effective touchscreen that can operate with simple tap inputs in rugged environments, resistive is the way to go. For more advanced and intuitive touchscreen technology with higher quality applications, choose capacitive touchscreens.

A surface capacitive touchscreen uses a transparent layer of conductive film overlaid onto a glass sublayer. A protective layer is then applied to the conductive film. Voltage is applied to the electrodes on the four corners of the glass sublayer to generate a uniform electric field. When a conductor touches the screen, current flows from the electrodes to the conductor. The location of the conductor is then calculated based on the activity of the currents. Surface capacitive touchscreens are often used for large screen panels.

Projected capacitive touchscreens are extremely precise and quick to respond and are typically found on smaller devices such as iPhones, iPod touches, or iPads. Unlike the surface capacitive touchscreens, which use four electrodes and a transparent conductive film, the projected capacitive touchscreens use a vast amount of transparent electrodes arranged in a specific pattern and on two separate layers. When a conductor moves near the screen, the electrical field between the electrodes changes, and sensors can instantly identify the location on the screen. Projected capacitive touchscreens can accurately register multi-touch events.

Selecting the most suitable type of touch screen for your project can improve device functionality and durability, which can mean a significant increase in customer adoption.

This article highlights the unique advantages and drawbacks of common touch screen technology, to help product design engineers make an informed decision.

Resistive touch is a legacy form of touch screen technology that was broadly popular for many years, but has been replaced by capacitive touch for many applications. Currently, resistive touch has a smaller range of common uses, but can still capably address certain needs.

The core elements of a resistive touch screen are two substrate layers, separated by a gap filled with either air or an inert gas. A flexible film-based substrate is always used for the top layer, while the bottom layers substrate can be either film or glass. A conductive material is applied to the inner-facing sides of the substrate layers, across from the air gap.

When a user applies pressure to the top surface, the film indents and causes the conductive material on the top layer to make an electrical contact with the conductive surface of the bottom layer. This activity creates a difference in voltage that the system registers as a touch. The location of this contact is pinpointed on the X and Y axes, and the touch controller then interprets the action. Because physical force is needed for a resistive touch screen to function, it is similar to a mechanical switch.

Resistive touch screens must be calibrated before they are used to ensure accurate and reliable operation. A user must apply pressure to the four corners of the screen, and sometimes on its center, to calibrate the screen with the rest of the system via a lookup database.

Because resistive touch screens interpret physical pressure as a touch, they are effective in a variety of environments using single touch. Any object capable of applying force to the screen can be used with the same result. For example, in applications where end users wear gloves, resistive touch screens offer reliable single-touch functionality.

Since resistive touch screens area actuated via mechanical force, they continue to function as intended even when liquids or debris are present on the surface. This makes them especially useful in situations where substances could disrupt the function of other types of touch screens. For example, on single-touch applications within agricultural equipment, boats and underwater machinery.

Besides the functional advantages of resistive touch screens, price is a common reason why OEMs select this option. In projects where cost is a top concern, companies can use this option to realize savings that may not be possible with alternatives.

The configuration of a resistive touch screen removes the possibility of gestures, such as pinching and zooming, or any actions requiring multi-touch functionality. These screens cannot determine the location of a touch if more than one input is present.

In terms of visibility, the film substrate commonly used as the top surface in resistive touch screens is less transmissive than glass. This leads to reduced brightness and a certain level of haze compared to touch screens with a top layer of glass. The film layer can also expand or contract based on temperature, which alters the distance between the two layers and affects touch accuracy. Additionally, the film substrates are susceptible to scratches and can start to wear away with repeated use, necessitating occasional recalibration or replacement over time.

Capacitive touch screens were invented before resistive touch screens. However, early iterations of this technology were prone to sensing false touches and creating noise that interfered with other nearby electronics. Due to these limitations, resistive touch screens and other options, like infrared touch screens, dominated the industry.

With more development and refinement of controller ICs, projected capacitive (PCAP) touch screens became the preferred touch technology for a majority of applications. For example, this technology is now commonly used on tablets, laptops and smartphones. Though PCAP stands for “projected capacitive (PCAP) touch”, it’s more commonly referred to as “capacitive touch”.

The foundation of PCAP touch screens is an array of conductors that create an electromagnetic field. As a user touches a PCAP screen, the conductive finger or object pulls or adds charge to that field, changing its strength. A touch controller measures the location of this change and then instructs the system to take a certain action, depending on the type of input received.

For a device with PCAP touch technology to acknowledge an input, users simply need to touch the screen. No physical pressure is required, unlike resistive touch screens.

Another key difference from resistive touch technology is that PCAP screens can accommodate a variety of inputs, with different gestures and more contact points instructing the system to take a variety of actions. PCAP touch can support multi-touch functionality, swipes, pinches, and zoom gestures which aren’t possible with resistive touch screens.

The value that comes with recognizing multiple inputs is a clear and positive differentiator for PCAP touch screens. Users can initiate a variety of commands, providing more functionality in devices where this technology is used. Consider how consumers now expect smartphones, tablets, and interactive laptop screens to support actions requiring two fingers, like pinching and zooming. In more specialized settings, such as multi-player gaming applications, PCAP touch screens can support more than 10 inputs at a single time.

PCAP touch screens do not require initial calibration, offering a simpler experience than resistive touch screens. Additionally, PCAP touch screens are highly accurate even as they support a variety of gestures and subsequent actions by the system.

Since their top layer is usually made of glass, PCAP touch screens offer a high degree of optical transmission and avoid the appearance of haze to users. Additionally, the glass top layerprovides improved durability compared to the film top layer of resistive touch screens – even for the largest sizes of up to 80 inches (and growing).

Operation in environments where a PCAP screen may be exposed to liquids or moisture — including conductive liquids like salt water — is possible through specialized controller algorithms and tuning. PCAP technology has evolved to support medical glove and thick industrial glove operation, as well as passive stylus operation.

PCAP touch screens can be customized with different cover lens materials (soda lime, super glasses, PMMA) based on application specific needs. Cover lenses can be ruggedized with chemical strengthening and substrates that improve impact resistance. This can be especially valuable for public-facing applications, like ATMs, gas pump displays, and industrial applications. Specialized films or coatings – such as AG (anti-glare), AR (anti-reflective), AF (anti-fingerprint) – can be added to the cover lens substrate to improve optical performance.

Unlike resistive touch screens, PCAP touch screens depend on variations in an electrical field to operate. While a passive stylus can activate this screen, a non-conductive tool like a pencil can’t.

If cost is a top concern for a project, PCAP may not align with budget limits. It is a more expensive technology than resistive screens, although it continues to grow more accessible in terms of price as the technology advances and improves.

The below table compares the advantages and disadvantages of projected capacitive touch vs resistive touch screens.CharacteristicsPCAP TouchResistive TouchRequires calibrationNoYes

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The construction of a capacitive touch screen,mainly to plate a transparent film conductor layer on the glass screen,then add a protective glass to the outside of the conductor layer,plate narrow electrodes on all four sides of the touch screen,a low voltage alternating electric field is formed in the electrical conductor.When you touch the screen,due to the existence of the human body electric field,a coupling capacitor is formed between the finger and the conductor layer,the current from the four electrodes will flow to the contacts,the current strength is proportional to the distance from the finger to the electrode,the controller behind the touch screen can calculate the ratio and strength of the current,then can accurately calculate the location of the touch point.

Compared with the resistive touch screens that are common in the market at that time,capacitive touch screen has obvious advantages,no pressure is needed to generate the signal,while the resistive touch screen is activated by pressure.Second,the capacitive touch screen has a long average life.Third,for the resistive touch screen, the upper film needs to be thin enough to be elastic so as to be bent downward to contact the underlying film, so it is easily damaged.And the covers of capacitive touch screen can be thicker, also have glass protection and have good scratch resistance, which can better protect conductors and sensors.In addition, capacitive touch screen is more durable, not easy to aging, high temperature resistance.Moreover, the double-glass design of capacitive touch screen can effectively prevent the impact of external environmental factors on the touch screen,even if the screen is stained with dirt, dust or oil stains, the capacitive touch screen can still accurately calculate the touch position.the more important thing is,at this time, the touch screen has evolved from an early analog touch screen to a digital touch screen, can achieve multi-touch.

There are a variety of touch technologies available today, with each working in different ways, such as using infrared light, pressure or even sound waves. However, there are two touchscreen technologies that surpass all others - resistive touch and capacitive touch.

There are advantages to both capacitive and resistive touchscreens, and either can be suited for a variety of applications dependent on specific requirements for your market sector.

Resistive touchscreens use pressure as input. Made up of several layers of flexible plastic and glass, the front layer is scratch resistant plastic and the second layer is (usually) glass. These are both coated with conductive material. When someone applies pressure to the panel, the resistance is measured between the two layers highlighting where the point of contact is on the screen.

Some of the benefits of resistive touch panels include the minimal production cost, flexibility when it comes to touch (gloves and styluses can be used) and its durability – strong resistance to water and dust.

In contrast to resistive touchscreens, capacitive touchscreens use the electrical properties of the human body as input. When touched with a finger, a small electrical charge is drawn to the point of contact, which allows the display to detect where it has received an input. The result is a display that can detect lighter touches and with greater accuracy than with a resistive touchscren.

If you want increased screen contrast and clarity, capacitive touch screens are the preferred option over resistive screens, which have more reflections due to their number of layers. Capacitive screens are also far more sensitive and can work with multi-point inputs, known as ‘multi-touch’. However, because of these advantages, they are sometimes less cost-effective than resistive touch panels.

Although capacitive touchscreen technology was invented long before resistive touchscreens, capacitive technology has seen more rapid evolution in recent years. Thanks to consumer electronics, particularly mobile technology, capacitive touchscreens are swiftly improving in both performance and cost.

At GTK, we find ourselves recommending capacitive touchscreens more regularly than resitive ones. Our customers almost always find capacitive touchscreens more pleasant to work with and appreciate the vibrancy of image that cap touch TFTs can produce. With constant advancements in capacitive sensors, including new fine-tuned sensors that work with heavy duty gloves, if we had to pick just one, it would be the capacitive touchscreen.

Touch screens have become very commonplace in our day-to-day lives. Devices using touch panels to enable user interaction without the use of keyboard or mouse. But do you know there are couple distinctively different types of touch screens? The five most common types are: Resistive, Surface Capacitive, Projected Capacitive, Surface Acoustic Wave and Infrared.

Resistive Touch is the most widely used touch technology these days. Because it is cheaper to make and easier to use in different environments. A resistive touch screen is composed of two very thin layers of material, separated by a thin gap. The top layer is typically some type of clear polycarbonate material, while as the bottom layer is made from rigid material. LCD manufacturers normally use PET film and glass for these layers. The upper and bottom layers are lined with conducting material like indium tin oxide (ITO), facing each other, separated by a narrow gap. When a user touches the screen, two metallic layers make contact, it creates a change in resistance.

In a 4-wire analog setup, both the top and bottom layers contain two electrodes called “bushbar”. These electrodes are oriented perpendicular to one another.

Electrodes on the top are positive and negative Y axis, while the ones on the bottom are positive and negative X axis. Using this setup, screen can sense the coordinates where the two layers have come in contact.

When user’s finger or stylus makes an area of the two layers touch, the sensing wire sends the voltage for the coordinates to device processor. With fewer components and a simpler design, the 5-wire analog circuit is a bit more durable than other designs.

The most sensitive resistive touch screen design is that of the 8-wire sensing circuit. Its layout is similar to the 4-wire one, but each of the “bushbar” connects with two wires.

Capacitive touch panel technology relies on the capacitance of the human body, and not on mechanical pressure like resistive technology. There are two types of capacitive touch panels – surface capacitive and projected one.

Surface Capacitive Touch are the second most popular type of touch screens on the market. In a surface capacitive touch panel a thin glass surface covers capacitive touch screen. Under this glass surface, lies a thin layer of transparent electrodes on top of LCD glass panel.

Projected Capacitive is like Surface Capacitive, with two main advantages: besides bare finger, it can also be activated with fingers inside thin surgical or cotton gloves; and it enables multi-touch activation.

Beneath the glass with protective cover, there is a pattern of electrode layers – or the matrix. This pattern forms the plane of X and Y coordinates which the controller uses to calculate the event of touch.

SAW (Surface Acoustic Wave) touch screen utilizes a series of piezoelectric transducers and receivers along the sides of the glass plate to create an invisible grid of ultrasonic waves on the surface. When the panel is touched, a portion of the wave is absorbed. This allows the receiving transducer to locate the touch point and send this data to the computer. SAW monitors can be activated by a finger, gloved hand, or soft-tip stylus. SAW monitors offer easy use and high visibility.

Infrared touch screen monitors do not overlay the display with an additional screen or screen sandwich. Instead, infrared monitors use IR emitters and receivers to create an invisible grid of light beams across the screen. This ensures the best possible image quality. When an object interrupts the invisible infrared light beam, the sensors are able to locate the touch point.

As the name suggests, resistive touch LCD screen works on the basis of a pressure applied to LCD screen. A resistive touchscreen consists of several thin layers. The layers comprise of a bottom glass panel that is followed by two resistive circuit layers which are coated with electrically conductive thin metallic layers (e.g. ITO) separated by a slim gap consisting of spacer dots.

When pressure is applied on the screen with a finger or stylus, the outer resistive layer is pushed onto the inner layer. The two metallic conductive layers come into contact, causing a current loop and generating a change in resistance on both vertical and horizontal axis. The change is detected by the sensors located on the screen"s edges which in turn find out the exact location by using the horizontal-vertical coordinates to indicate the touch point.

Minimal production cost- resistive touchscreens are easier to make due to its simple structure and cost less when compared with otherLCD touch technologies.

Activate with any object - as stated above, anything that can apply pressure on resistive touch screen will trigger a touch action and detected by resistive touch sensors. This property makes resistive touch screen the preferred choice in industrial and medical settings, where operators may use gloves on the LCD touch screen.

Less sensitive to stray stimuli - how a touch action is detected by resistive touch screen determines liquid spills/snow or surface contaminants won"t cause the touch screen to react unintentionally. And this is very important for industrial and outdoor environments.

No shattered glass risk - most LCD touch screen technologies use glass as outer touch layer. This is usually not allowed in food and beverage facilities, to avoid shattered glass contamination. Resistive touch screen uses a tough polycarbonate outer layer, which can contain shattered glass in case the LCD screen is cracked.

Resistive touch LCD screens have been used widely for many years. It is a well-proven and trusted solution for building human-machine interface. Here is an example of "How to implement LCD display resistive touch".

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Touchscreens have changed the way people expect to interact with their devices. When it comes to smartphones and tablets, touch is the way to go. Even handheld game consoles, laptops, and car navigation systems are moving towards touch. Manufacturers of these devices need to give their respective consumers the responsiveness these consumers are looking for. Selecting the right TFT-LCD display to use for different devices is important.

For touch-sensitive displays, two types of technologies are used: resistive and capacitive. The main difference is in how they respond to touch. Mobile phone comparison site Omio indicates that resistive technology is more accurate but capacitive technology is more responsive.

To elaborate on that, resistive touchscreens allow input from fingers and non-finger objects, like a stylus. A stylus has a smaller point than a finger and makes interaction on a resistive screen more accurate. This makes the technology suitable for devices whose applications require high accuracy, like sketching and pinpoint games. Mobile devices that use a stylus typically have resistive touchscreens.

Capacitive touchscreens, on the other hand, offer more responsiveness with better optical clarity and multi-touch performance. They detect more complex finger gestures. These qualities are shown to be more important for general interaction so it’s more dominant in smartphones and tablets, as well as in other devices with small to medium screen sizes.

As you can see, capacitive screens get general usage while resistive screens cater to more specific applications. With this, TFT-LCD module manufacturers, like Microtips Technology, focus on continuously improving capacitive screen technology.

Electronic Design states that many technological advances can be used to integrate touch sensors directly into the display. In some, manufacturers stack-up the touch sensors and integrate the controller with the display driver ICs. These advances allowed thinner and smarter capacitive touchscreens – a trend that you see in many devices today. For example, Windows phones originally worked exclusively with resistive touchscreen technology but later on moved over to capacitive. If the continuous development of capacitive touchscreen technology becomes successful, these screens may soon have abilities they don’t possess at the moment, such as hover support, non-finger support, and many more.

Resistive touch screen composed of two sheets made of electrically resistant material .i.e., conductive bottom and the top layer with spacer dots suspended in between. The value of resistance gets affected due to the generation of pressure between screen and finger when the finger touches the touch panel’s surface.

Through variant shifts in the value of resistance, the controller detects the position of the contact by exchanging signals. Eagle Touch provides top-rated optical solutions for industrial applications with its widened diversity of low-cost resistive touch screen panels.

We purpose to understand high quality disfigurement with the output and supply the top service to domestic and overseas buyers wholeheartedly for Tft Lcd Display Panel With Resistive Touch Screen, Monitor Lcd Panel, Rugged Touch Screen Monitor, Tft Flat Screen Monitor,Lcd Touch Screen. We sincerely hope to determine some satisfactory interactions with you in the in the vicinity of long term. We"ll hold you informed of our progress and stay up for building steady small business relations along with you. The product will supply to all over the world, such as Europe, America, Australia,Cyprus, Belgium,Rome, Brunei.Our aim is to help customers realize their goals. We are making great efforts to achieve this win-win situation and sincerely welcome you to join us. In a word, when you choose us, you choose a perfect life. Welcome to visit our factory and welcome your order! For further inquiries, please do not hesitate to contact us.

Our company specializes in developing solutions that arerenowned across the globe and meet expectations of the most demanding customers. Orient Display can boast incredibly fast order processing - usually it takes us only 4-5 weeks to produce LCD panels and we do our best to deliver your custom display modules, touch screens or TFT and IPS LCD displays within 5-8 weeks. Thanks to being in the business for such a noteworthy period of time, experts working at our display store have gained valuable experience in the automotive, appliances, industrial, marine, medical and consumer electronics industries. We’ve been able to create top-notch, specialized factories that allow us to manufacture quality custom display solutions at attractive prices. Our products comply with standards such as ISO 9001, ISO 14001, QC 080000, ISO/TS 16949 and PPM Process Control. All of this makes us the finest display manufacturer in the market.

Without a shadow of a doubt, Orient Display stands out from other custom display manufacturers. Why? Because we employ 3600 specialists, includingmore than 720 engineers that constantly research available solutions in order to refine strategies that allow us to keep up with the latest technologiesand manufacture the finest displays showing our innovative and creative approach. We continuously strive to improve our skills and stay up to date with the changing world of displays so that we can provide our customers with supreme, cutting-edge solutions that make their lives easier and more enjoyable.

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Choosing services offered by Orient Display equals a fair, side-by-side cooperation between the customer and our specialists. In each and every project, we strive to develop the most appropriate concepts and prototypes that allow us to seamlessly deliver satisfactory end-products. Forget about irritating employee turnover - with us, you will always work with a prepared expert informed about your needs.

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Capacitive touch screen technologyUSES the human body’s current induction to work. The capacitive touch screen is a four-layer composite glass screen. The inner surface of the glass screen and the interlayer are coated with one layer of ITO respectively. The outermost layer is a thin layer of silica soil glass protective layer. When the finger touches the metal layer, the user and the touch screen surface form a coupling capacitor due to the electric field in the human body.

The capacitor is a direct conductor to the high-frequency current, so the finger sucks a small current away from the contact point. The current flows from the electrodes at the four corners of the touch screen respectively, and the current flowing through the four electrodes is proportional to the distance from the fingers to the four corners. The controller calculates the precise proportion of the four currents to get the position of the touchpoint.

In order to realize multi-touch on a capacitive screen, it is necessary to add electrodes of mutual capacitance. In a simple words, it is to divide the screen into blocks and set a group of mutual capacitance modules in each area to work independently. Therefore, the capacitive screen can independently detect the touch situation of each area and simply realize multi-touch after processing.

Capacity Touch Panel USES the current induction of the human body to work. The capacitive screen is a four-layer composite glass screen. The inner surface of the glass screen and the interlayer are coated with ITO (indium sikgold oxide nano). The outermost layer is a protective layer of silica glass with a thickness of 0.0015mm.

Whena user capacitive touch screen, the electric field due to the human body, your fingers and face form a coupling capacitance, because the working plane to have a high-frequency signal, so the fingers on a very small current, respectively from the current screen in the four corners of the electrode, and theoretically through the four electrodes with the finger to the four corners of the current is proportional to the distance, the controller through the precise calculation of the four current ratio, it is concluded that location. It can achieve 99% accuracy, with a response speed of less than 3ms.

Projective capacitive touch screens etch different ITO conductive circuit modules on two layers of ITO conductive glass coatings. The etched patterns on the two modules are perpendicular to each other and can be thought of as sliders with continuous changes in X and Y directions. As the X and Y architectures are on different surfaces, their intersection forms a capacitor node. One slider can be used as the drive wire and the other as the detection wire. When a current passes through one of the wires in the drive wire, if there is a signal of a change in the capacitance outside, it will cause a change in the capacitance node on the other layer of wire. The change in capacitance can be detected by measuring the electrical circuit connected to it, and then converted to A digital signal by A/D controller, which can be processed by A computer to obtain the (X, Y) axis position, so as to achieve the positioning target.

During operation, the controller successively supplies power to the driving wire, thus forming a specific electric field between each node and the wire. Then scan the sensor line one by one to measure the capacitance change between the electrodes so as to achieve multi-point positioning. When the finger or touch medium is close, the controller can quickly detect the change of capacitance between the touch node and the wire, and then confirm the position of the touch.

One axis is driven by a set of AC signals, and the response across the touch screen is measured by electrodes on the other axis. Users call this’ transversal ‘sensing or projective sensing. The sensor is plated with the ITO pattern of the X and Y-axis. When the finger touches the touch screen surface, the capacitance under the touchpoint increases according to the distance of the touchpoint. The continuous scanning on the sensor detects the change of capacitance value, and the control chip calculates the touchpoint and returns it to the processor.

Projective capacitive touch screens are multi-finger touch. These two capacitive touch screens have the advantages of high light transmittance, fast response speed, and long life, etc. The disadvantages are: with the change of temperature and humidity, the capacitance value will change, resulting in poor work stability, often drift phenomenon, need to frequently proofread the screen, and can not wear ordinary gloves for touch positioning.

The projected capacitive touch screen can be divided into the capacitance and mutual capacitance screen two types, one of the more common mutual capacitance screen as an example, the internal electrode and receiving electrode by the driver, drive electrode signal low voltage high frequency projected onto the receiving electrode form stable current, when human exposure to the capacitance screen, earth due to the human body, fingers and capacitance screen to form an equivalent capacitance, and the high-frequency signal by the equivalent capacitance into the ground, in this way, the receiver receives charge is reduced, when fingers near the transmitter, electric charge, the more significant, according to the receiving end receives the current strength of to determine the touchpoint.

Arrays of transverse and longitudinal electrodes are made from ITO on the surface of the glass. These transverse and longitudinal electrodes form capacitors with the ground respectively. This capacitor is commonly referred to as self-capacitance, that is, the capacitance of the electrode to the ground. When the finger touches the capacitive screen, the capacitance of the finger will be superimposed on the capacitance of the screen, thus increasing the capacitance of the screen.

During touch detection, the horizontal and longitudinal electrode arrays are respectively detected from the capacitive screen. According to the changes of capacitance before and aftertouch, the horizontal coordinates and longitudinal coordinates are determined respectively, and then the touch coordinates of the plane are combined. The scanning method of self-capacitance is equivalent to projecting the touchpoints on the touch screen to the X-axis and Y-axis directions respectively, and then calculating the coordinates in the X-axis and Y-axis directions respectively, and finally combining them into the coordinates of the touchpoints.

If it is a single touch, the projection in the X and Y direction is unique, and the combined coordinates are unique. If there are two touches on the touch screen and the two touches are not in the same X direction or the same Y direction, then there are two projections in the X and Y direction respectively, and the combined coordinates are 4.Apparently, only two of the coordinates are real, and the other two are known as ghost points. Therefore, self – the capacitive screen can not achieve true multi-touch.

The mutual capacitor screen also USES ITO to make the transverse electrode and the longitudinal electrode on the glass surface. The difference between it and the self-capacitor screen is that the place where the two groups of electrodes cross will form a capacitor, that is, the two groups of electrodes form the electrodes of the capacitor respectively. When a finger touches a capacitive screen, the coupling between two electrodes near the touchpoint is affected, thus changing the capacitance between the two electrodes.

When the mutual capacitance is detected, the transverse electrode will send out excitation signals successively, and all the longitudinal electrodes will receive signals at the same time. In this way, the capacitance value of all the intersection points of the transverse and longitudinal electrodes can be obtained, that is, the capacitance value of the entire two-dimensional surface of the touch screen. The coordinates of each touchpoint can be calculated according to the two-dimensional capacitance variation data of the touch screen. Therefore, even if there are multiple touchpoints on the screen, the actual coordinates of each touchpoint can be calculated.

The advantage of the mutual capacitive screen is less wiring, and can simultaneously identify and distinguish the difference between multiple contacts since the capacitive screen can also sense multiple contacts, but because the signal itself is fuzzy, so can’t distinguish. In addition, the induction scheme of the mutual capacitive screen has the advantages of fast speed and low power consumption, because it can measure all the nodes in a driveline at the same time, thus reducing the number of acquisition cycles by 50%. The dual-electrode structure has the function of self-shielding external noise and can improve signal stability at a certain power level.

In any case, the touch position is determined by measuring the distribution of signal changes between the X and Y electrodes, and a mathematical algorithm is then used to process the changed signal levels to determine the XY coordinates of the touchpoint.

•   Capacitive schemes last longer because the components in the capacitive touch screen do not need to move at all. In a resistive touch screen, the top layer of the ITO film needs to be thin enough to be elastic so that it bends down and touches the bottom layer of the ITO film.

•   The choice of capacitor or resistor depends largely on the object touching the screen. If it is a finger touch, the capacitive touch screen is a better choice. If a stylus is needed, whether plastic or metal, a resistive touch screen will do. A capacitive touch screen can also use a stylus but requires a special stylus to work with it.

•   Surface capacitances can be used for large touch screens and are relatively low, but they currently do not support gesture recognition: inductive capacitances are mainly used for small and medium-sized touch screens and can support gesture recognition.

•   Capacitive technology is wear-resistant, has a long service life, and has low maintenance costs when users use it, so the overall operating costs of manufacturers can be further reduced.

•   Capacitive touch screens are designed to support multi-touch technology and are less responsive and less prone to wear and tear than resistive touch screens.

STONE provides a full range of 3.5 inches to 15.1 inches of small and medium-size standard quasi TFT LCD module, LCD display, TFT display module, display industry, industrial LCD screen, under the sunlight visually highlight TFT LCD display, industrial custom TFT screen, TFT LCD screen-wide temperature, industrial TFT LCD screen, touch screen industry. The TFT LCD module is very suitable for industrial control equipment, medical instruments, POS system, electronic consumer products, vehicles, and other products.

The capacitive touch screen is stacked on the tft lcd display, there are two ways to make it, one is frame bonding, another one is optical bonding. the frame bonding means the capacitive touch screen attached on the tft screen by the double glue tapes via the lcd frame on the four sides. the optical bonding means the full lamination about the capacitive touch screen and tft lcd screen, that is the lamination is via OCA glue, and full lamination about the capacitive touch panel and tft lcd screen.

Projected capacitive touch (PCT) technology is a capacitive technology which allows more accurate and flexible operation, byetchingthe conductive layer. AnX-Y gridis formed either by etching one layer to form a grid pattern ofelectrodes, or by etching two separate, parallel layers of conductive material with perpendicular lines or tracks to form the grid; comparable to thepixelgrid found in manyliquid crystal displays(LCD).

Resistive touch screen: pressure is required to make contact with each layer of the screen, and it can be operated with fingers (even with gloves), nails, stylus, etc. Supporting stylus is very important in the Asian market, where gesture and text recognition is valued.

Capacitive touch screen: The smallest contact from the surface of a charged finger can also activate the capacitive sensing system under the screen. Non-living objects, nails, and gloves are invalid. Handwriting recognition is more difficult.

Resistive touch screen: The accuracy is at least a single display pixel, which can be seen when using a stylus. It is convenient for handwriting recognition and helps to operate under the interface with small control elements.

Capacitive touch screens: Capacitive screens from different manufacturers are 10% to 50% more expensive than resistive screens. This extra cost does not matter to flagship products, but it may discourage mid-priced phones.

Resistive touch screen: The fundamental characteristics of the resistive screen determine that its top is soft and needs to be able to be pressed down. This makes the screen very prone to scratches. Resistive screens require protective film and relatively more frequent calibration. The advantage is that the resistive touch screen device using the plastic layer is generally less vulnerable to damage and less likely to be broken.

Capacitive touch screen: The outer layer can use glass. Although this is not indestructible and may shatter under severe impact, the glass is better for daily rubbing and staining.

Capacitive touchscreen displays work by detecting the electrical properties of the human body. When you touch the screen, your body’s natural capacitance is transferred to the touchscreen display. This change in capacitance is registered by the processor of the device as a touch pcs.

Capacitive touchscreen displays are made up of a thin sheet of glass that contains a grid of hair-thin lines of conductive metal. The grid lines in one direction are called the driving lines and provide a constant electric current. Lines perpendicular to the grid lines are called the sensing lines, and they detect this electric current.

At every point where the driving lines and sensing lines cross each other, they create an electrostatic field registered as neutral by the processor of the device. When you touch the screen, your body’s natural capacitance is transferred to the touchscreen display. This change in capacitance is registered by the processor of the device as a touch event.

Capacitive touch screen monitor 32 inch displays are highly accurate and responsive, making them ideal for use in industrial and commercial applications.

A resistive touchscreen display consists of a glass panel that is coated with transparent conductive material. The conductive material is separated from the glass by a thin layer of air. When a user presses on the screen, the conductive material makes contact with the glass and completes an electrical circuit. This process is known as mutual capacitance.

In this Arduino touch screen tutorial we will learn how to use TFT LCD Touch Screen with Arduino. You can watch the following video or read the written tutorial below.

For this tutorial I composed three examples. The first example is distance measurement using ultrasonic sensor. The output from the sensor, or the distance is printed on the screen and using the touch screen we can select the units, either centimeters or inches.

The next example is controlling an RGB LED using these three RGB sliders. For example if we start to slide the blue slider, the LED will light up in blue and increase the light as we would go to the maximum value. So the sliders can move from 0 to 255 and with their combination we can set any color to the RGB LED,  but just keep in mind that the LED cannot represent the colors that much accurate.

As an example I am using a 3.2” TFT Touch Screen in a combination with a TFT LCD Arduino Mega Shield. We need a shield because the TFT Touch screen works at 3.3V and the Arduino Mega outputs are 5 V. For the first example I have the HC-SR04 ultrasonic sensor, then for the second example an RGB LED with three resistors and a push button for the game example. Also I had to make a custom made pin header like this, by soldering pin headers and bend on of them so I could insert them in between the Arduino Board and the TFT Shield.

Here’s the circuit schematic. We will use the GND pin, the digital pins from 8 to 13, as well as the pin number 14. As the 5V pins are already used by the TFT Screen I will use the pin number 13 as VCC, by setting it right away high in the setup section of code.

As the code is a bit longer and for better understanding I will post the source code of the program in sections with description for each section. And at the end of this article I will post the complete source code.

I will use the UTFT and URTouch libraries made by Henning Karlsen. Here I would like to say thanks to him for the incredible work he has done. The libraries enable really easy use of the TFT Screens, and they work with many different TFT screens sizes, shields and controllers. You can download these libraries from his website, RinkyDinkElectronics.com and also find a lot of demo examples and detailed documentation of how to use them.

After we include the libraries we need to create UTFT and URTouch objects. The parameters of these objects depends on the model of the TFT Screen and Shield and these details can be also found in the documentation of the libraries.

Next we need to define the fonts that are coming with the libraries and also define some variables needed for the program. In the setup section we need to initiate the screen and the touch, define the pin modes for the connected sensor, the led and the button, and initially call the drawHomeSreen() custom function, which will draw the home screen of the program.

So now I will explain how we can make the home screen of the program. With the setBackColor() function we need to set the background color of the text, black one in our case. Then we need to set the color to white, set the big font and using the print() function, we will print the string “Arduino TFT Tutorial” at the center of the screen and 10 pixels  down the Y – Axis of the screen. Next we will set the color to red and draw the red line below the text. After that we need to set the color back to white, and print the two other strings, “by HowToMechatronics.com” using the small font and “Select Example” using the big font.

Next is the distance sensor button. First we need to set the color and then using the fillRoundRect() function we will draw the rounded rectangle. Then we will set the color back to white and using the drawRoundRect() function we will draw another rounded rectangle on top of the previous one, but this one will be without a fill so the overall appearance of the button looks like it has a frame. On top of the button we will print the text using the big font and the same background color as the fill of the button. The same procedure goes for the two other buttons.

Now we need to make the buttons functional so that when we press them they would send us to the appropriate example. In the setup section we set the character ‘0’ to the currentPage variable, which will indicate that we are at the home screen. So if that’s true, and if we press on the screen this if statement would become true and using these lines here we will get the X and Y coordinates where the screen has been pressed. If that’s the area that covers the first button we will call the drawDistanceSensor() custom function which will activate the distance sensor example. Also we will set the character ‘1’ to the variable currentPage which will indicate that we are at the first example. The drawFrame() custom function is used for highlighting the button when it’s pressed. The same procedure goes for the two other buttons.

getDistance(); // Gets distance from the sensor and this function is repeatedly called while we are at the first example in order to print the lasest results from the distance sensor

Here’s that function which uses the ultrasonic sensor to calculate the distance and print the values with SevenSegNum font in green color, either in centimeters or inches. If you need more details how the ultrasonic sensor works you can check my particular tutorialfor that. Back in the loop section we can see what happens when we press the select unit buttons as well as the back button.

Ok next is the RGB LED Control example. If we press the second button, the drawLedControl() custom function will be called only once for drawing the graphic of that example and the setLedColor() custom function will be repeatedly called. In this function we use the touch screen to set the values of the 3 sliders from 0 to 255. With the if statements we confine the area of each slider and get the X value of the slider. So the values of the X coordinate of each slider are from 38 to 310 pixels and we need to map these values into values from 0 to 255 which will be used as a PWM signal for lighting up the LED. If you need more details how the RGB LED works you can check my particular tutorialfor that. The rest of the code in this custom function is for drawing the sliders. Back in the loop section we only have the back button which also turns off the LED when pressed.

In order the code to work and compile you will have to include an addition “.c” file in the same directory with the Arduino sketch. This file is for the third game example and it’s a bitmap of the bird. For more details how this part of the code work  you can check my particular tutorial. Here you can download that file:

getDistance(); // Gets distance from the sensor and this function is repeatedly called while we are at the first example in order to print the lasest results from the distance sensor