Supporting Multi-Touch Functions

Multi-touch technology might be easy to use, but the mechanics behind it are far more complex. While several technologies support multi-touch functions, museums may find that certain ones suit an exhibition’s needs better than others. Choosing the right multi-touch platform is the first step in creating an interactive and personal experience for visitors. 

My previous article, Multi Touch Technology and the Museum, explored how capacitive grids create intuitive touch screens. However, the popular capacitive method is only one of the technologies that support multi-touch functions. Several lesser-known methods may better fit a museum’s vision in creating a multi-touch experience. 

Capacitive Touch Panels

As previously mentioned, capacitive touch panels are the first and most popular type of multi-touch technology. They are also the most popular multi-touch technology used in museums. This method recognizes minor changes in electrical currents upon contact. Capacitive touch systems can be used in two types of touch screens: surface capacitive touch panels and projective capacitive touch panels. While simple in structure and inexpensive, surface capacitive screens do not support multi-touch functions.

In contrast, the complex internal structure of projective capacitive touch panels supports multi-touch use. Projective capacitive touch systems contain a computer chip underneath a layer of transparent electrodes. Insulated by plastic or glass, these electrodes allow the device to recognize two touch points at the same time. Many of us encounter this multi-touch technology on a daily basis on our smartphones or tablets. Additionally, some museums employ capacitive touch when renting out iPhones or iPod Touches to visitors.

While projective capacitive touch systems are high-precision tools for smaller screens, such as smartphones, they are not recommended for larger screens. On larger screens, projective capacitive touch technology results in slower transmission between the electrical current causing processing delays. Additionally, the insulated screen may interfere with image quality. For this reason, museums must look elsewhere for large multi-touch screens.

Infrared Touch Overlays

 IR Touch Overlay used for interactive white board technology

IR Touch Overlay used for interactive white board technology

There are several options for museums interested in multi-touch technology on larger screens. Many professionals in the field provide museums with infrared (IR) touch overlays. IR touch overlays use infrared light to create an invisible grid of infrared beams and sensors. These sensors detect when a finger touch or solid object breaks the plane of the grid.

This accurate method is great option for museums that need a larger multi-touch screen. In fact, the grid can recognize up to 40 simultaneous touches, allowing several users to use the screen at once. With no insulating glass or plastic layer, images used for IR touch overlays tend to provide great image quality. Additionally, IR overlays are commonly used for interactive white board technology in the classroom.

Unfortunately, IR touch overlays may encounter some problems. While such overlays are durable, they tend be fairly expensive. Additionally, bright light or other solid objects may interfere with multi-touch system. Museums must be conscious of this when determining where to place an IR touch overlay screen.

Optical Touch Screens

Another method that utilizes infrared light is optical touch screen technology. Optical touch screen technology uses multiple optical sensors that detect motion. This method requires infrared cameras that monitor the screen’s view. Sensors in these cameras detect when a user’s finger or any other solid object blocks the infrared light.

The optical touch sensors scan a user’s finger the moment before contact with the screen. This means it requires no physical contact with the screen to function. Unfortunately, this also means the system detects solid object that get close to the screen, rendering it an especially sensitive technology.

 Diagram of optical touch screen technology function

Diagram of optical touch screen technology function

Although optical touch screen technology allows for greater multi-touch possibilities, it has similar issues to the IR touch screen. Often, large objects can interfere with the optical touch system or the large optical touch screen may experience ghosting, or unprompted performance. Additionally, sunlight or reflections can hinder performance. On top of these difficulties, the complex technological system is difficult to manufacture correctly on a large scale.

These various multi-touch technologies can create transformative experiences for visitors. However, each system presents unique advantages and disadvantages. With this in mind, museums may find systems such as infrared overlays and optical touch systems better fit their needs and desires. Whether you want a 40-foot wall to greet visitors or small interactive panels in your exhibition, these technologies can meet your multi-touch function needs.