When you need to purchase in bulk or customize touchscreens for a project, you may encounter different touch technologies. What are the characteristics of each type of touchscreen, and how should you choose? This article will give you a complete guide.
Resistive Touch Screen
Work Principle of Resistive Touch Screen
A resistive touch screen consists of an upper membrane, spacer dots, a substrate, and a control circuit. Its operating principle is that when you press the screen, different conductive layers will come into contact, the resistance will be changed, and the contact points will be detected. Based on the positioning method, resistive touch screens are further divided into four-wire and five-wire types.
Advantages of Resistive Touch Screen
- The activation of a resistive touch screen is triggered by mechanical pressure. You can operate it not only with a finger, but also with a fingernail, while wearing gloves, or using a plastic stylus.
- High immunity to electromagnetic interference. Resistive touch screens do not rely on weak capacitance changes, and they can still operate stably in strong EMI environments.
- The material cost of a resistive touch screen is always lower than that of other types of touch screens. Also, its yield rate is quite high, and its cost per screen is low.
- It can operate in harsh environments. High humidity, dusty, and oily environments do not affect the operation of a resistive touch screen.
Disadvantages of Resistive Touch Screen
- Low light transmittance and average display quality. The light transmittance of a resistive touch screen is only 70%–85%, which is lower than that of other types of screens.
- Because the touch input requires pressing, resistive touch screens are not suitable for sliding and are relatively laborious to operate.
Capacitive Touch Screen
Work Principle of Capacitive Touch Screen
A capacitive touch screen detects the touch positions by sensing changes in capacitance, which are caused by your body or a conductive object interacting with the screen, and responds to your touch accordingly. The controller will continuously scan the capacitance value on each electrode. When the capacitance in a certain area exceeds the set threshold, your touch will be sensed.
Advantages of Capacitive Touch Screen
- It can be operated with a light touch. Capacitive touch screens do not require pressing, and they just need a gentle touch, which can enhance your user experience.
- The light transmittance is quite high. The light transmittance of capacitive screens is generally over 90%, and their color and brightness performance are quite good.
- Resistant to wear and easy to clean. Tempered glass is always used for the surface of the capacitive touch screens, which is scratch-resistant and easy to clean.
Disadvantages of Capacitive Touch Screen
- Touch input requires the use of a conductive object. Non-conductive objects such as gloves, plastic, or wooden sticks cannot be used to operate the screen.
- The cost of a capacitive touch screen is always high. Its material cost is high, the manufacturing process is complex, and algorithms must be frequently applied.
- Because the capacitance changes with temperature, it may perform poorly under extreme temperatures.
Infrared Touch Screen
Work Principle of Infrared Touch Screen
The surface of the infrared touch screen has a grating emitted by an infrared emitter. When you touch the screen with your finger or other object, it will block or reflect some infrared light. At this point, the photoelectric receiver on the screen border detects the signal change and can identify the touch position.
Advantages of Infrared Touch Screen
- You can achieve touch control with any medium, including fingers, gloves, and hard objects.
- Infrared touch screens support 10 or more points of multi-touch and can also recognize gestures.
- The surface of an infrared touch screen can be made of ordinary glass or tempered glass, which is highly resistant to wear.
- Water, dust, and oil do not affect touch input.
Disadvantages of Infrared Touch Screen
- Transparent glass or plastic blocks little light, and it is often difficult to register touch.
- The frame must have a wide width to install the transmitters and receivers. Therefore, it cannot be made extremely narrow.
- The controllers, photoelectric receivers, and algorithms of infrared touch screens are all complex, and their cost is generally higher.
Surface Acoustic Wave
Work Principle of Surface Acoustic Wave
Surface Acoustic Wave is also known as SAW. It consists of a display glass layer, transducers, reflectors, and controllers. Its work principle is that there are sound waves on the screen surface, which are constantly detected by the controller. When you touch the screen, you will absorb or scatter a portion of the sound waves, and the transducer will detect the amplitude changes, thereby enabling touch operation.
Advantages of Surface Acoustic Wave
- A light tap on the screen is sufficient to trigger it, and you do not have to press the screen.
- The touch accuracy of surface acoustic screens is high, with positioning errors typically within ±1–2 mm.
- Its transmittance is typically more than 90%, and the brightness and color display are good.
- The surface glass of the screens is wear-resistant and easy to clean.
Disadvantages of Surface Acoustic Wave
- Dust, liquids, and oil stains may absorb or scatter sound waves, causing touch failure or accidental touch.
- The SAW screen does not support multi-touch. Simultaneous touching with multiple fingers can interfere with the sound wave signal, making it impossible to accurately locate.
- The transducers, reflectors, controllers, and algorithms are expensive, and both installation difficulty and required installation precision are quite high.
Optical Imaging Touch Screen
Work Principle of Optical Imaging Touch
An optical imaging touch screen consists of a display, cameras, optically calibrated corner points, and a controller. The four corner cameras of the screen will cover the entire touch area. When your finger touches the screen, the camera will capture the corresponding image. Then, the image processing algorithm will respond accordingly and output to the system.
Advantages of Optical Imaging Touch Screen
- You can touch with any object, and don’t need to consider whether it is conductive or not, including fingers, gloves, pens, and sticks.
- With multiple cameras, the screen can simultaneously detect multiple touch points. It also supports gesture operations such as zooming and rotating.
- Optical imaging can cover large screens of over 100 inches. And increasing the screen size will not significantly increase the cost.
- The top layer of glass hardly wears even with long-term use, and it is also easy to clean.
Disadvantages of Optical Imaging Touch Screen
- Optical imaging touch screens are sensitive to ambient light, which may interfere with the cameras.
- In optical imaging touch screens, the accuracy of touch control is affected by multiple factors, and the workload of calibration is very large.
- The process of touch control requires going through image capture, image processing, coordinate calculation, and other procedures. Therefore, it usually takes a long time to respond.
- It will take up a lot of space. To achieve an optical imaging touchscreen, you need to place the camera and optical components around the screen frame.
Projected Capacitive Touch Screen
Work Principle of Projected Capacitive Touch Screen
Projected capacitive touch screens are an upgrade of capacitive touch technology. The controller on the glass surface applies an alternating voltage to the electrodes, creating a uniform electric field.
Because the human body is a conductor, and it has inherent capacitance, when your finger approaches the screen, it couples a portion of the electric field. Then, the capacitance value at the corresponding point will change, and the system will respond.
Advantages of Projected Capacitive Touch Screen
- Natively supports multi-touch. It supports multi-touch with 5, 10, or more than 20 touch points, and can also accurately recognize your gestures such as zooming, rotation, and swiping.
- Because the triggering mechanism is capacitive coupling, it usually provides a natural touch feel and a relatively fast response speed.
- Its touch accuracy is very high, and the accuracy at the center and edges of the screen is nearly identical.
- Its light transmittance is extremely high, which usually brings out high contrast and high brightness.
Disadvantages of Projected Capacitive Touch Screen
- Only fingers or a capacitive stylus can operate the screen, while non-conductive objects cannot.
- Its cost is quite high. Its electromagnetic interference protection design is very complex, and the surface also requires an extremely thin cover glass.
- In some extreme environments, such as strong electromagnetic fields, heavy precipitation, or high noise conditions, the touch functionality of the screen may decrease.
| Technology | Resistive Touch | Capacitive Touch | Infrared Touch | Surface Acoustic Wave | Optical Imaging | Projected Capacitive
|
| Multi-Touch | Single-point | Multi-point | Multi-point | Single-point | Multi-point | Multi-point |
| Usable Object | Finger, glove, or stylus | Finger or capacitive pen | Any object | Finger or soft object | Any object | Finger or capacitive pen |
| Transparency | Medium | Very high | High | High | High | Extremely high |
| Accuracy | Medium | High | Medium | High | Medium | High |
| Environmental Robustness | High | Medium | Ordinary | Low | Low | Medium |
| Cost | Low | Medium | High | High | High | High |
| Typical Application | Industrial, Medical, POS, ATM | Smartphones and tablets | Large-screen ads | ATM, ticketing, and info terminals | Large interactive displays | High-end smartphones, tablets, and interactive ads |
Single-Point Touch and Multi-Point Touch
The single-point touch refers to the screen that can only recognize one touch point at a time. It is commonly found in early resistive touch screens, SAW screens, and some infrared screens. The experience of the single-point touch screens is even weaker. You can’t achieve complex functions such as two-finger zooming and screenshot on the screen. However, their cost is usually lower, and they also have stronger anti-interference capability.
Multi-touch refers to the screen having the ability to recognize two or more touch points simultaneously, sometimes even more than ten. It is always used in projected capacitive (P-Cap) and optical imaging touchscreens.
A multi-point touch screen can achieve complex functions such as zooming, rotating, dragging, etc. Some can also achieve adjusting the stroke by judging the pressure size, multi-finger operation, etc. For example, when you perform a five-finger pinch gesture on an iPad, you can quickly return to the home screen. Multi-point touch screens can offer you a better touch experience, but the cost is often higher.
Typical Applications of Touchscreens
Smartphones, Tablets, and Laptops
Consumer electronic products such as mobile phones, tablets, laptops, and smartwatches began to incorporate touch functions in the early 21st century. Currently, they always use projected capacitance technology, which can achieve high precision and gesture-rich multi-touch.
Industrial Control Panels
In industrial fields such as industrial HMI and factory automation panels, touch control functions need to be configured. They generally use durable, reliable, dust-proof, and water-proof resistive touch technology.
Interactive Whiteboard for Teaching
An interactive whiteboard can use projection screens, LED, LCD, or OLED displays to achieve touch functionality. Depending on the type of display, the interactive whiteboards generally use resistive, optical imaging, or projected capacitive touch technologies.
Self-Service Terminal
Self-service terminals include scenarios such as ATMs, ticket machines, ordering machines, and information inquiry machines. They usually need to be durable, tamper-proof, and waterproof. Common self-service terminals typically use resistive touch screens, projected capacitive screens, infrared touch screens, and optical imaging touch screens.
Why Does a Touchscreen Occasionally Not Respond?
Occasionally, you may encounter a situation where the touchscreen malfunctions. The possible reasons are as follows:
- Screen damage or scratches: If the touch-sensing layer of resistive or capacitive screens is damaged, certain areas may become unresponsive.
- Hardware issues: The touch layer aging, malfunctioning controllers, or bad connections may result in the touchscreen becoming unresponsive.
- Software or system faults: Driver errors, heavy system resource usage, or defects in touch algorithms may lead to touchscreen malfunctions.
- Environmental factors: Direct sunlight may prevent optical imaging or infrared screens from detecting touch; extreme temperatures or water on the screen may also affect touch performance.
- Improper operation: Using a non-conductive object on a capacitive touchscreen, having too small a contact area, insufficient contact, or operating too quickly may cause touch failure.
Moreover, if your screen has a problem with touch failure, you can troubleshoot it by cleaning the screen, checking the connection, restarting the screen, and updating the software. If you can’t determine the cause of the touch failure, it is recommended to send it to a professional institution for repair.
How to Choose an Appropriate Touch Technology for a Display?
As a retailer, integrator, or project manager, when customizing a touchscreen, you need to consider these factors to determine which touch technology you need:
Operation Mode
First, confirm whether your screen will be operated with bare fingers, gloves, a stylus, or other non-conductive objects. For example, for finger touch, you can choose projected capacitive (P-Cap), optical imaging, or infrared technology; for glove operation, you can choose resistive, infrared, or optical technology.
Multi-touch Requirements
Confirm whether your screen requires specific gesture operations or multi-user simultaneous input. If multi-touch is required, projected capacitive or optical imaging is the ideal choice; if multi-touch is not needed, resistive or SAW screens can fully meet your needs.
Screen Size
Different screen sizes require different technologies. For example, for large screens over 65 inches, optical imaging is the most suitable choice.
Environmental Conditions
If the screen is to operate outdoors or in harsh environments, infrared, optical, or high-protection resistive screens that resist water vapor and dust interference are suitable.
Budget
Among all types of touchscreens, resistive touchscreens are the cheapest, followed by infrared and optical imaging, while projected capacitive screens are the most expensive. You can choose based on your budget.
The Future Trend of Touchscreen Technologies
In the near future, touchscreens are evolving toward faster response, more accurate recognition, greater scratch resistance, and better water resistance. Hence, the application of projected capacitive screens will be more widespread. On the other hand, the interaction methods will become increasingly advanced. More complex gestures and even touchless interactions will become increasingly common.
FAQs
Which is Better, Resistive or Capacitive Touch screens?
Resistive and capacitive touch screens both have their own advantage. If you prefer a smoother touch experience and better brightness performance, then a capacitive touch screen is the better choice; if you prefer stronger dust and water resistance, then a resistive touch screen is the better choice.
Can a Capacitive Touch Screen be Operated with Other Body Parts, Such as Knuckles?
Generally speaking, except for fingers, other body parts, like knuckles and toes, can also operate a capacitive touch screen. However, when the touch area is small or the electric field is weak, the responsiveness may be lower than that of fingers.
Can Scratches Degrade the Performance of a Touch Screen?
In most cases, the scratches on the screen surface have almost no impact on touch sensitivity; they only affect your visual experience. But for resistive touch screens, scratches on the screen surface may affect the accuracy of touch control.
Is Touch Functionality Necessary for Advertising Displays?
It depends on your specific needs. When the display is only used for playing videos, pictures, or other information, you don’t have to make it have touch functionality; if you want to encourage cutomers to participate in your activities, or obtain information through the advertising screen, in order to enhancing their sense of participation and the effectiveness of the advertisement, you can purchase one with touch control function.
Final Thoughts
There are several technologies that can achieve touch, and each has its own characteristics. When making a selection, you should decide based on your specific requirements. If you want to customise an LED screen with touch functionality, JINGYLED may be your ideal choice. We specialize in manufacturing screens of various types, sizes, and resolutions to meet your different needs.
If you have any further questions, feel free to contact us!
