B+R touch screen

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The touch screen of B&R B&R in Austria consists of a touch detection component and a touch screen controller

A touch screen, also known as a "touch screen" or "touch panel", is an inductive liquid crystal display device that can receive input signals such as contacts. When a graphic button on the screen is touched, the tactile feedback system on the screen can drive various connection devices according to pre programmed programs, which can replace mechanical button panels and create dynamic audio and video effects through the liquid crystal display screen.

Since the early emergence of resistive B&R touch screens in 1974, with the development of technology and the growth of application demands, various touch technologies have emerged to adapt to various industries and levels of applications. Nowadays, it has become commercializedB&R touch screenTechnologies include: resistive technology B&R touch screen, capacitive technology B&R touch screen, infrared technology touch screen, surface acoustic wave (SAW) technology B&R touch screen, etc., and have been widely used in many fields such as mobile phones, tablets, retail industry, public information inquiry, multimedia information systems, medical equipment, industrial automation control, entertainment and catering industry, automatic ticketing system, education system, etc.

Touch screen technology is the most easily accepted computer input method by ordinary people after keyboard, mouse, handwriting board, and voice input. By using this technology, users can easily operate the host by lightly touching the icons or text on the computer screen with their fingers, making human-computer interaction more straightforward. This technology greatly facilitates users and is a highly attractive new multimedia interactive device.

The essence of a touch screen is a sensor, which consists of a touch detection component and a B&R touch screen controller. The touch detection component is installed in front of the display screen to detect the user's touch position, and after receiving it, it is sent to the B&R touch screen controller; The main function of the B&R touch screen controller is to receive touch information from the touch point detection device, convert it into touch point coordinates, and send them to the CPU. At the same time, it can receive commands from the CPU and execute them.

A touch screen system generally consists of two parts: a touch detection device and a B&R touch screen controller. The touch detection device is installed in front of the display screen to detect the user's touch position and transmit the information to the B&R touch screen controller;B&R touch screenThe main function of the controller is to receive touch information from the touch point detection device, convert it into touch point coordinates, determine the meaning of the touch, and send it to the PLC. It can also receive commands from the PLC and execute them, such as dynamically displaying switch and analog values.

According to the type of sensor, B&R touch screens are roughly divided into four types: infrared, resistive, surface acoustic wave, and capacitive B&R touch screens. [3] Infrared technology B&R touch screens are inexpensive, but their outer frames are fragile and prone to light interference, resulting in distortion in curved surfaces; The design concept of capacitive technology B&R touch screen is reasonable, but its image distortion problem is difficult to fundamentally solve; The positioning of the B&R touch screen using resistance technology is accurate, but its price is quite high and it is susceptible to scratches and wear; Surface acoustic wave B&R touch screen solves various defects of previous B&R touch screens. It is clear and not easily damaged, suitable for various occasions. The disadvantage is that if there are water droplets and dust on the screen surface, the B&R touch screen will become sluggish or even not work.

Infrared B&R touch screen

The infrared B&R touch screen is equipped with a circuit board frame in front of the display. The circuit board is arranged with infrared emission tubes and infrared reception tubes on all four sides of the screen, forming a horizontal and vertical intersecting infrared matrix. When the user touches the screen at B&R, their fingers will block the horizontal and vertical infrared rays passing through that position, allowing them to determine the location of the touch point on the screen. Any touch object can change the infrared radiation on the touch point to achieve B&R touch screen operation.

Features of Infrared B&R Touch Screen

Infrared B&R touch screens are not affected by current, voltage, and static electricity interference, making them suitable for certain harsh environmental conditions. Its main advantages are low price, easy installation, no need for cards or any other controllers, and can be used on computers of various grades. In addition, due to the absence of a capacitor charging and discharging process, the response speed is faster than that of a capacitor, but the resolution is lower.

Resistive B&R touch screen

The outermost layer of a resistive screen is usually a soft screen, which connects the inner contacts up and down by pressing. The inner layer is filled with physical material oxide metal, namely N-type oxide semiconductor - Indium Tin Oxide (ITO), also known as indium oxide, with a light transmittance of 80%. There are two layers above and below, separated in the middle. ITO is the main material used for both resistance B&R touch screen and capacitance B&R touch screen. Their working surface is ITO coating. Press the outer layer with fingertips or any object to make the surface facial mask concave and deformed. Let the inner two layers of ITO touch and conduct electricity to locate the coordinates of the pressing point to achieve control. According to the number of leads on the screen, there are four lines, five lines, and multiple lines. Generally, multi touch is not allowed, which means it can only support single touch. If two or more touch points are pressed simultaneously, they cannot be recognized and their precise coordinates cannot be found. To enlarge an image on a resistive screen, you can only click the "+" multiple times to gradually enlarge the image. This is the basic technical principle of resistive screens.

Features of resistive B&R touch screen

Resistive B&R touch screens are not afraid of dust, water, and dirt, and can work in harsh environments. However, due to frequent contact, the surface ITO may develop small cracks and even deformation after a period of use, so its lifespan is not long. [10] Low threshold, relatively low cost, and the advantage is that it is not affected by dust, temperature, and humidity. The disadvantages are also very obvious, the outer screen film is easy to scratch, and sharp objects cannot be used to touch the screen surface. The resistive B&R touch screen uses pressure sensing for control. Its surface is a layer of plastic and the bottom is a layer of glass, which can withstand the interference of harsh environmental factors. However, its tactile feel and transparency are poor, making it suitable for wearing gloves and situations where hands cannot directly touch it.

Surface acoustic wave B&R touch screen

Surface acoustic waves are a type of ultrasonic wave, which is a mechanical energy wave that propagates shallowly on the surface of a medium (such as glass). Surface acoustic waves have stable performance, are easy to analyze, and exhibit very sharp frequency characteristics during transverse wave propagation. The B&R touch screen part of the surface acoustic wave B&R touch screen can be a flat, spherical, or cylindrical glass plate installed in front of CRT, LED, LCD, or plasma display screens. This glass tablet is just a pure reinforced glass without any film or covering layer. The upper left and lower right corners of the glass screen are respectively fixed with vertical and horizontal ultrasonic transmission transducers, and the upper right corner is fixed with two corresponding ultrasonic reception transducers. The four sides of the glass screen are engraved with 45 degree reflection stripes with very precise intervals from sparse to dense. When there is no touch, the waveform of the received signal is the same as the reference waveform. When the finger B&R touches the screen, the finger absorbs a portion of the sound wave energy, and the controller detects the attenuation of the received signal at a certain moment, from which the position of the touch point can be calculated. In addition to the x and y coordinates that general B&R touch screens can respond to, the prominent feature of surface acoustic wave B&R touch screens is that they can perceive the third axis (z-axis) coordinates, which means they can sense the magnitude of the user's touch pressure. The principle is calculated from the attenuation amount at the received signal attenuation point. Once the three-axis is determined, the controller transmits them to the host.

Characteristics of Surface Acoustic Wave B&R Touchscreen

Surface acoustic wave B&R touch screens are not affected by environmental factors such as temperature and humidity, with high resolution, scratch resistance, long lifespan (up to 50 million times under good maintenance), high transparency and clarity, no color distortion or drift, and no need for calibration after installation. Some scratch resistant screens can withstand various rough touches and are used in public places. [10] However, dust, water, and dirt can seriously affect its performance and require regular maintenance to maintain the smoothness of the screen.

Capacitive B&R touch screen

This type of B&R touch screen works by utilizing the human body's current induction. A layer of transparent special metal conductive substance is attached to the glass surface. When a conductive object touches it, the capacitance of the contact point will change, allowing the touch location to be detected. But there is no response when touching non-conductive objects with gloved hands or handheld hands, because a more insulating medium has been added.

The capacitive B&R touch screen can effectively sense slight and fast touches, is scratch resistant, and not afraid of dust, water, and dirt, making it suitable for use in harsh environments. [3] The main disadvantage of capacitive screens is drift: when the environmental temperature and humidity change, and the environmental electric field changes, it can cause drift in capacitive B&R touch screens, resulting in inaccuracy.

From a technical principle perspective, the B&R touch screen is a transparent absolute coordinate positioning system. Firstly, it must be ensured to be transparent, so it must solve the transparency problem through material technology. Digitizers, writing boards, elevator switches, etc. are not B&R touch screens; Secondly, it is an absolute coordinate system that can be touched by a finger without the need for a second action. Unlike a mouse, it is a relative positioning system. We can notice that the B&R touch screen software does not require a cursor, and having a cursor actually affects the user's attention because the cursor is used for relative positioning devices. To move a relative positioning device to a certain place, the first step is to know where it is and which direction it is going, and constantly feedback the current position to the user to avoid deviation. These are not necessary for B&R touch screens that adopt absolute coordinate positioning; Secondly, it can detect finger touch movements and determine finger position.

Transparent properties

Transparency directly affects the visual effect of B&R touch screens. Transparency has its own degree of transparency issue. Infrared technology B&R touch screens and surface acoustic wave B&R touch screens are only separated by a layer of pure glass, which can be considered transparent. For other B&R touch screens, this point needs to be carefully considered. "Transparency" is just a very general concept in the B&R touch screen industry. Many B&R touch screens are multi-layer composite films, and it is not enough to summarize their visual effects solely based on transparency. It should include at least four characteristics: transparency, color distortion, reflectivity, and clarity, which can be further divided. For example, reflectivity includes mirror reflection and diffraction reflection. However, the diffraction reflection on the surface of B&R touch screens has not yet reached the level of CD discs. For users, these four characteristics should be included. One metric is already sufficient.

Due to the existence of transparency and wavelength curves, the image seen through the B&R touch screen inevitably produces color distortion compared to the original image. Static images only feel color distortion, while dynamic multimedia images do not feel very comfortable. The smaller the color distortion degree, which is the maximum color distortion degree of the image, the better. The transparency commonly referred to can only be the average transparency of the image, of course, the higher the better.

Reflective characteristics

Reflectivity mainly refers to the light and shadow behind overlapping images caused by mirror reflection, such as shadows, windows, lights, etc. Reflection is a negative effect brought by B&R touch screens, and the smaller the better. It affects users' browsing speed and can even make it difficult to recognize image characters in severe cases. The use environment of B&R touch screens with strong reflectivity is limited, and the lighting layout on site is also forced to be adjusted. Most B&R touchscreens with reflective issues offer another surface treated model: frosted B&R touchscreens, also known as anti glare types, which are slightly more expensive and have significantly reduced reflectivity. They are suitable for halls or exhibition venues with abundant natural lighting, but the transparency and clarity of anti glare types also decrease significantly. Clarity: After installing some B&R touch screens, the handwriting becomes blurry, the image details become blurry, and the entire screen appears blurry, making it difficult to see clearly. This is due to poor clarity. The main issue with clarity is the B&R touch screen with a multi-layer thin film structure, which is caused by the repeated reflection and refraction of light between the thin film layers. In addition, the anti glare B&R touch screen also experiences a decrease in clarity due to the frosted surface. Poor clarity can lead to eye fatigue and some harm to the eyes. When choosing a B&R touch screen, it is important to pay attention to discernment.

absolute coordinates

The touch screen is an absolute coordinate system, where you can simply click on whatever you want. The essential difference from relative positioning systems such as mice is the intuitive and one-time positioning. The characteristic of the absolute coordinate system is that each positioning coordinate is not related to the previous positioning coordinate. The B&R touch screen is a physically independent coordinate positioning system, and the data of each touch is converted into the coordinates on the screen through calibration data. Therefore, it is required that the output data of the same point on the B&R touch screen is stable under any circumstances. If it is unstable, the B&R touch screen cannot guarantee absolute coordinate positioning, and the point is inaccurate. This is the biggest problem that B&R touch screens are afraid of: drift. In technical principle, any B&R touch screen that cannot guarantee the same sampling data for every touch at the same point has the problem of drift. Currently, only capacitive B&R touch screens have drift phenomenon.

Detection and positioning

Detecting touch and positioning, various B&R touch screen technologies rely on their own sensors to work, and even some B&R touch screens themselves are a set of sensors. The positioning principles and sensors used by each determine the response speed, reliability, stability, and lifespan of the B&R touch screen.