From telephones, office equipment, speakers, digital photo frames, TV control keys, remote controls, GPS systems, car keyless control, to medical monitoring equipment, touch devices are everywhere! Every industry, every product type, every size, and every application is inseparable from touch technology.

In fact, if the product has an LCD or keyboard, designers may need to consider how to design a product that uses touch technology. Unfortunately for designers, when designing touch screens, there are many different solutions, with various performances, and of course different design considerations. So now is the time to understand the technology in depth and evaluate your product line. Only in this way can we become a leader in the market, and a good appearance design is the starting point of the design.

In-depth Analysis of Touch Technology

Understanding the design needs is the most important first step in touch product design. Many providers in the touch screen supply chain usually provide a lot of confusing different components, and more often some providers join together to provide a value chain for end customers.

1. Front panel or frame

The front panel or frame is the outermost layer of the end product. In some products, the outer frame encloses a transparent cover plate to avoid being affected by external harsh weather or humidity, and also to prevent the following sensing products from being scratched and damaged. Sometimes, the outermost frame simply covers the top of the touch sensor. In this case, it is just a decoration.

2. Touch controller

Usually, the touch controller is a small chip located between the touch sensor and the PC or embedded system controller. The chip can be assembled on the controller board inside the system, or it can be placed on a flexible printed circuit (FPC) glued to the glass touch sensor. The touch controller will extract the information from the touch sensor and convert it into information that the PC or embedded system controller can understand.

3. Touch sensor

The touch screen "sensor" is a transparent glass plate with a touch-responsive surface. The sensor is placed on the LCD so that the touch area of the panel can cover the visible area of the display. There are many different touch sensing technologies on the market today, each of which uses a different method to detect touch input. Basically, these technologies cause current to flow through the panel when touched, thereby generating a voltage or signal change. This voltage change will be sensed by the touch controller to determine the touch position on the screen.

4. Liquid crystal display (LCD)

The vast majority of touch screen systems are used on traditional LCDs. The LCD selection method for touch products is basically the same as in traditional systems, including resolution, clarity, refresh speed, cost, etc. But another major consideration in touch screens is the radiation level. Since the technology in the touch sensor is based on the tiny electrical changes caused by the panel being touched, an LCD that can radiate a lot of electrical noise is a difficult point in the design.

5. System software

The touch screen driver software can come from the original manufacturer (such as the embedded OS in the mobile phone), or it can be software added later (such as adding a touch screen to a traditional PC). The software should enable the touch screen to work with the system controller. It will tell the product's operating system how to parse the touch event information from the touch controller. In PC-type applications, most touchscreen drivers work like a mouse. This makes touching the screen very similar to pressing the mouse continuously at the same location on the screen. In an embedded system, the embedded control driver must compare the information that appears on the screen with the position where the touch is received.

Three Main Touch Technologies

Resistive touch technology: Resistive touch technology is the most commonly used touch screen technology. It is used in high-traffic applications and has immunity to water drops and other residues on the screen. Resistive touch screens are usually the lowest cost solution. Because it responds to pressure, you can touch it with your fingers, gloved hand, touch pen, or other objects like credit cards.

Surface capacitive touch technology: The surface capacitive touch technology provides a clearer display than the plastic film commonly used in resistive touch. In surface capacitive display, sensors located in the four corners of the display detect changes in capacitance due to touch. This type of touch screen can use fingers or other capacitive objects to achieve touch excitation.

Protective capacitive touch: Protective capacitive touch is a technology that has only recently entered the market. This technology can also provide excellent light transmittance, but it also has some advantages that are much better than surface capacitive touch. Projection-type capacitive touch does not require position calibration and can provide much higher position accuracy. Another exciting aspect of the projected capacitive touch is that it can support multiple touches at the same time.

Designing Industrial Touch Screens

There is no doubt that the touch screen has an excellent appearance. They began to define a new type of user interface and industrial design standards that are being widely accepted worldwide. In devices ranging from heart rate monitors to the latest all-in-one printers, touch screens are rapidly becoming the technical design standard. But in addition to the beautiful appearance, the touch screen also provides unmatched safety performance, resistance to severe weather, abrasion resistance, and can use new touch technologies such as multi-touch to open up a new market. Many kinds of products can be realized using touch technology, so designers must deeply understand the ecosystem of the technology and the usability of the technology currently used.