Speakers and Displays
Loudspeakers perform the opposite function of a microphone converting elec-
trical energy back into acoustical energy.
Types of Speakers
Speakers vary in the range of audio frequencies reproduced and the dispersion
pattern of the sound. Loudspeaker types include cones and compression drivers.
Cones can be used for reproduction of the bass-, mid- and high-frequency
spectrum, while compression drivers are used only for mid- and high-range fre-
quencies. Since no single loudspeaker driver can accurately reproduce the entire
range of frequencies several drivers may be utilized in a single speaker enclosure.
Displays
A video display device presents information visually. Video displays come in a
wide variety of sizes and core technologies and are utilized in a broad range of
environments. Selection of a display is based on the dimensions of the viewing
area, lighting, and the type of content and materials to be displayed.
Display devices can be front or rear projected. Front projection is the pre-
ferred display in presentation environments (such as classrooms and meeting
rooms) because it is less expensive than rear protection and requires much less
space. The viewing image for the audience is projected onto a front screen
which reflects the image.
Rear screen projection is preferred in bright, well-lighted environments. Essen-
tially light from a rear screen projector is transmitted through the screen. The
screen is made of material that transmits the light with relatively little distortion.
Rear and front screen projections can use LCD, cathode ray tube (CRT), or
digital light projector (DLP) technology.
Major types of video displays include the following:
Plasma Screen
Plasma screens are basically a network of chemical compounds called “phos-
phors” contained between two thin layers of glass that, when excited by an
electric pulse, produce colors, light, and a picture. The picture of a plasma
screen is bright and rich with color. Screens can be as large as 80 inches.
Plasma screens are thin, lightweight, have a wide viewing angle and offer good
pictures under normal room lighting conditions.
174 Smart Building Systems for Architects, Owners, and Builders