Until relatively recently, persons who are blind, have low vision or are learning disabled or otherwise print handicapped are denied access and orientation that the general population takes for granted in every day life. Finding their way is a challenging event often ending with asking strangers' help. Whether getting on the right bus, finding a restroom or a telephone, determining directions to elevators or exits, crossing streets or understanding directories in public places, these populations are placed at a great disadvantage and often in danger. Directional "wayfinding" devices have not existed to provide them the ability to "read and see" remote signs.
In recent years an information and wayfinding system has been developed for assisting blind, low-visioned and otherwise print-handicapped individuals. The system, marketed under the trademark Talking Signs.RTM., consists of infrared transmitters and receivers. Transmitters are placed on key signs in the environment which continually transmit the message of the sign. The receiver is carried by the person who activates it when direction or information is desired.
Transmitters of lightwave signals, especially infrared signals, such as used in the Talking Signs.RTM. system referred to above, must effectively deliver a frequency modulated infrared signal (preferably continuous) having a unique set of characteristics so that the signal can be sensed by a portable, hand-held receiver which in turn converts the signal into intelligible communication for the person carrying the receiver. For example, the transmitters may comprise an array of single or multi-channel emitters each of which delivers the frequency modulated infrared signal in the pattern of a cone having a beam width in the range of about 10.degree. to about 50.degree. at a modulated frequency of about 25 KHz with band width in the range of about 3 to about 6 KHz and having an infrared carrier frequency in the range of about 850 to about 950 nanometers. At the same time the transmitter system must be suitably covered to protect the system against excessive accumulation in the system of dust or other debris, and to minimize or deter vandalism, theft, breakage or other activities that would interfere with proper performance of the transmitter system.