„A single display that can be used by anyone for simple and convenient control of the entire technology within a building, including all communication, information and entertainment media. Both on site and while travelling.” Stuttgart, 1999
Touch screen is a durable and reliable interface in home automation appliance systems, is one of the user-friendliest tools available to reach the public with a message.
A touch interface allows users to navigate a computer system by touching icons or links on the screen. With the right software interface, it is easily use and interact with a touch screen enhanced system. It is being used in a wide variety of applications to improve human-computer.
Figure 6.2 Touch screens
By integrating the input device with the display, valuable workspace can be saved. And with a graphical interface, operators can monitor and control complex operations in real-time by simply touching the screen.
The control system touch screens can range from a 15" (diagonal viewing area) full-color high-resolution active matrix LCD displays to a 4" grayscale LCD. All come with a touch sensitive overlay, this allows you to simply touch the screen to select or control a desired feature.
The different touch screens can display pictures, video, symbols, and words. By touching different areas of the screen you can step through simple menu screens to select and control the different features in your home.
Each screen will always have basic lighting and volume controls available, as well as an icon to immediately return you to the main menu. Your main screen display (the display shown when the touch screen is inactive) may display any picture or graphical representation of your choice. With video capable touch screens, you could preview video sources before selection or the view the images from your video security monitoring cameras.
Touch screens can be built flush into walls, designed into furniture, put on coiled cords and moved between dedicated jacks in desired areas, or even made completely wireless if desired.
There are 3 types of touch screen displays:
1. Displays based on PC technology are standards-based and provide the most flexible solution. They can interface with your home controller and can also enable you to view IP cameras and access the web. When these displays are mounted on the wall, they are usually referred to as a Panel PC. On a tabletop, they can be either a touch screen PC or a tablet PC.
2. High-end remote controls can also make a great looking graphical display. One of the key advantages of this type of display is long battery life. It provides instant control of Room scenes, AV equipment, HVAC, security, and Groups of Actions with little or no additional programming needed.
3. A third option is the custom displays associated with a distributed AV system or those associated with a lighting system. They provides a program that can be loaded and provides instant control of Room scenes, AV equipment, HVAC, security, and Groups of Actions with little or no additional programming needed.
Figure 6.3 The structure of Touch screens
Most handheld touch screens today use resistive technology. In a resistive touch sensor, a conductive membrane is suspended over a conductive substrate.
The conductors are electrically resistive sheets with taps on the edges or corners. Pressure from a pen or finger bends the membrane into contact with the substrate to form an electrical circuit.
The controller locates the pen or finger by measuring the resistance between the point of contact and the edges or corners.
Performance with fingers is poor due to the need for physical pressure; it is difficult to tune the sensor to work well with both fingers and pens. Resistive sensors cannot distinguish pens from fingers, nor can they detect proximity of a pen or finger without actual pressure.
Capacitive touch screens use a thin layer of ITO (indium tin oxide) to sense the proximity of a finger by capacitive coupling they work extremely well for fingers but do not sense pens.
Inductive touch screens sense a pen containing a special resonant coil; other coils within the touch screen excite the resonant coil and detect the resulting ringing by magnetic proximity sensing.