A touch screen overlay is a technology that transforms a standard display into a touch-sensitive interface. It consists of a thin, touch-responsive layer placed over an existing screen, allowing users to interact with the display using their fingers or a stylus.
Unlike the built-in touch-sensitive layers found in native touch screen devices, a touch screen overlay is an independent accessory. While traditional touch screens are designed with integrated touch-sensitive layers made of flexible plastic or glass, overlays are external add-ons that provide touch functionality to non-touch displays.
The primary function of a touch screen overlay is to upgrade a standard display device, such as a Human-Machine Interface (HMI), by adding touch functionality. While some devices are inherently designed to support touch-based input, others lack this capability. However, with the installation of a touch screen overlay, even non-touch displays can be adapted for touch interaction.
Touch screen overlays are made from transparent or translucent materials that detect and respond to touch inputs. Various technologies enable this functionality, including projected capacitive, resistive, and infrared (IR) touch sensing, with IR being one of the most commonly used methods. Infrared overlays utilize a grid of infrared beams to identify the point where a user interrupts the flow of light to determine the exact location of the touch command. Each technology has its own set of advantages and disadvantages, influencing factors such as accuracy, durability, and cost.
One of the main advantages of touch screen overlays is their ability to easily add touch functionality to display devices that were not originally designed for touch interaction. Once installed, users can seamlessly operate the device using touch commands.
Another key benefit is cost-effectiveness. Touch screen overlays are relatively inexpensive, making them a popular choice for businesses looking to upgrade multiple display devices without investing in entirely new touch-enabled screens. By enhancing interactivity and creating a more intuitive user experience, overlays contribute to a more engaging and sophisticated interface.
However, touch screen overlays may not always match the precision, quality, and responsiveness of devices with built-in touch technology. They tend to be less accurate and may have slower response times compared to dedicated touch screen displays, which can impact user experience in applications requiring high precision.
An infrared (IR) touch screen consists of an LCD monitor paired with an IR touch frame equipped with LEDs and photodetectors. The frame includes an optical bezel or protective cover that allows LEDs to emit invisible infrared beams, forming an optical grid across the screen’s surface. When a user touches the screen, the touch interrupts the infrared beams, and the photodetectors register these disruptions to determine the exact touch location.
Due to their high accuracy, durability, and reliability, IR touch screens are widely used in retail, gaming, healthcare, manufacturing, and other interactive applications where precision and responsiveness are essential. However, the traditional IR touch sensor technology also has a few limitations.
Ambient light can cause problems with infrared touch screens. Touch detection can be hampered by strong sources of infrared light, such as strobing sunlight or bright interior illumination.
If a user interacts with the screen using a stylus that is too narrow to interrupt the infrared beams, the touch may not be registered. To ensure accurate detection, the stylus must be wide enough to break at least one of the infrared beams.
Infrared touch screens generally consume more power than capacitive or resistive touch screens. This is because they require a continuous emission of infrared light, often necessitating a more robust power supply.