Advantages and Disadvantages of Infrared Touch Screen

Touch screens are electronic visual displays that detect the presence and location of a touch within the display area. The term refers to directly touching the device's display with a hand or finger. Touch screens can also sense other passive objects, such as a stylus. However, if the object is active, like a light pen, the term "touch screen" may not apply.

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There are two main characteristics of touch screens. Firstly, they allow direct interaction with what is displayed, rather than indirect interaction through a cursor controlled by a mouse or touchpad. Secondly, touch screens enable users to perform actions without needing any intermediate device, such as a stylus, that needs to be held. These displays can be connected to computers or networks, functioning as terminals. They also play a significant role in the design of electronic devices such as personal digital assistants (PDAs), satellite navigation devices, mobile phones, and video game consoles.

History

The first "touch sensor" was developed by Dr. Sam Hurst, the founder of Elographics, while he was an instructor at the University of Kentucky. He named this sensor the "Elograph," which was patented by the University of Kentucky Research Foundation.

The Elograph was not transparent like modern touch screens, but it was a significant milestone in touch screen technology. In subsequent years, Sam Hurst and Elographics introduced the first touch screen with a transparent surface. In 1991, Elographics patented the five-wire resistance technology, which is still one of the most popular touch screen technologies in use today. Touch screens gained visibility with the creation of computer-assisted learning terminals, which emerged in the 1970s as part of the PLATO project. Soon after, touch screens became common in daily life, as many companies adopted them for kiosk systems in retail and travel settings, POS systems, ATMs, and PDAs, often using a stylus for data entry.

From 1985 to 1986, the Fairlight CMI music workstation used light pen technology, allowing users to interact with synthetic data and navigate menus. Later models switched from light pens to graphics tablets.

The HP-150, released in 1983, was one of the world's first commercial touch screen computers. Its touch screen monitor did not technically qualify as a true touch screen; instead, it contained a 9-inch Sony CRT surrounded by infrared transmitters and receivers that detected the position of non-transparent objects.

To this day, most consumer touch screens can only detect one point of contact at a time, although some can sense how hard a user is touching the screen. The commercialization of multi-touch technology has since changed this landscape.

Touch screen computers are widely used in hospitality and heavy industries, as well as in kiosks like museum displays or room automation systems, where traditional input devices like keyboards and mice might not offer sufficient interaction or responsiveness.

Historically, the development of touch screen technology involved a diverse range of aftermarket system integrators, while display, chip, or motherboard manufacturers largely abstained from offering such capabilities. Recently, display and chip manufacturers across the globe have recognized the benefits of integrating touch screen features into their products due to rising consumer demand.

Touch Screen Technologies

Various types of touch screen technologies are utilized across different fields, which can be summarized as follows:

Resistive

Resistive touch screen panels are composed of several layers, with two key electrically conductive layers separated by a narrow gap. When an object, like a finger or stylus, presses down on the panel’s surface, the two layers connect at that point. This creates a change in electrical current, registered as a touch event, which is sent to the controller for processing.

Surface Acoustic Wave

Surface acoustic wave (SAW) technology utilizes ultrasonic waves that travel through the touch screen panel. When an object, such as a finger or stylus, touches the panel, part of the wave is absorbed, registering the location of the touch event and relaying this information to the controller. However, SAW touch screens can be affected by pollutants on their surface.

Capacitive

A capacitive touch screen consists of an insulator like glass coated with a transparent conductor (indium tin oxide). The human body acts as a conductor, and when a finger touches the surface, it creates a distortion in the screen's static electricity field, measured as a change in electric capacity. Different technologies may be employed to determine the touch position, which is then processed by the controller.

Projected Capacitance

Projected Capacitive Touch (PCT) technology offers greater precision by etching the conductive layer. It forms an X-Y grid, allowing multiple touch points to be registered simultaneously. PCT supports writing with various objects, including fingers, gloved hands, or styluses, and is increasingly utilized in professional environments.

Infrared

Infrared touch screens use an array of X-Y infrared light-emitting diodes (LEDs) and photodetectors to map the interface, detecting interruptions in the LED beams caused by touches. This system recognizes various input types, including fingers or styluses, and is often used in outdoor applications where traditional capacitive technology may fail.

Advantages and Disadvantages of Infrared Touch Screens

Advantages

• Cost-effective, especially for larger screens.
• Excellent light transmission, leading to vibrant image quality.
• Supports multi-touch, facilitating interaction with multiple users simultaneously.
• Short response time, typically less than 8ms.
• Durable glass overlay minimizes the risk of scratches.
• Flexible customization for various monitor sizes.
• Ease of maintenance due to a simple assembly structure.
• Compatible with a variety of writing tools, including fingers, gloves, and pens.
• No need for calibration, simplifying user experience.
• No pressure needed for writing, reducing screen damage.

Disadvantages

• More sensitive to environmental conditions, such as direct sunlight.
• Potential issues in detecting very light touches.
• May require regular maintenance to ensure optimal performance.
• Can be affected by dirt and dust accumulation around the bezel.

Conclusion

Infrared touch screens present a unique set of advantages and disadvantages, making them suitable for a variety of applications. They are particularly valuable in contexts where multiple users need to interact with a screen simultaneously or where the technology must endure harsh environmental conditions. Understanding these factors is crucial for making informed decisions about implementing touch screen technology in various settings.