The present invention relates to the field of visual displays and more particularly to methods and apparatus for generating a visual display of light patterns responsive to an audio frequency input signal.
Visual display systems are known which employ light baffles to create compartments, and illuminate the compartments with combinations of light sources and filters for producing abstract lighting effects. Such devices thereby generate areas of light which are larger than individual bulbs, but nonetheless are discrete and stationary. Apparatus of this type are described in U.S. Pat. No. 4,622,881. Such devices are not driven by audio programming input. Rather, they are "stand alone," although their output may be coordinated with the beat of an audio program by use of a "beat detector" shown in FIG. 4 in the '881 patent.
Other known methods and apparatus for producing "light shows" include a series of band-pass filters for dividing an audio input signal into several components, each representing a particular band of frequencies. These component signals may be used to control a display unit comprising, for example, an array of light bulbs or light emitting diodes, so that each frequency component activates a particular light or group of lights. An apparatus of that type is shown in U.S. Pat. No. 4,355,348. In an apparatus of that type, the size of the visual display is equal to the size of the display unit, typically on the order of one or two feet square. Manufacture of a larger display unit employing the same techniques as shown in U.S. Pat. No. 4,355,348 would be bulky, expensive, and require a substantial amount of electrical power to operate. Whatever the size of the display unit, it comprises a number of discrete light sources, thereby limiting the size of the generated visual display.
Still other devices are known for controlling lights in a display unit responsive to the volume or power level of the audio input signal. Thus, such devices activate additional lights or different lights, as the level of the input signal varies.
Another apparatus for combining audio and visual effects is shown in U.S. Pat. No. 3,478,837. That patent shows a speaker including a rotating baffle for creating a tremolo or vibrato effect, coupled with a light bulb which is activated synchronously with the rotating baffle to produce what the inventor calls "optically enhanced vibrato." The visual aspect of that invention comprises a single flashing light bulb.
Laser lighting systems are known which employ a laser beam reflected off an orthogonal pair of mirrors onto a wall or other display surface for producing any one of a variety of predetermined display patterns. A light beam is directed so that it strikes one of the mirrors, then the other mirror, and finally a display surface. Each mirror is oscillated by an independent transducer including a magnet and drive coil. A pair of signal generators drive the coils. The apparatus includes a memory containing prestored driver information for controlling the signal generators. In operation, each mirror deflects the light beam in a different direction, resulting in a two-dimensional visual display pattern. Display systems of that type are difficult to manufacture, expensive, and require substantial input signal power to drive the coils. Further, the amount of mirror deflection, and hence the size of the display pattern, is quite limited.
Laser lighting systems of the foregoing type generally are responsive to a selected characteristic of an audio input signal. For example, changes in input signal volume and/or frequency are used to select among predetermined display patterns. Thus, the particular patterns selected for display and their sequence of display are determined by the audio signal, though each of the individual patterns is predetermined and information to generate it is prestored in the memory. Variations of the above-described types of equipment include multiple beam systems and systems having beam splitters for projecting repetitive images.
Display devices are also known that change display patterns automatically as a function of time, or in response to selected characteristics of an audio signal, as described above. The display pattern size may be modulated apparently responsive to the audio input by displaying progressively larger prestored patterns in response to higher audio input signal levels. In all of the above-described devices, the generated visual displays comprise one or more stationary light sources, or a light beam directed to traverse a predetermined path for displaying a predetermined pattern.
In summary, many existing devices for producing visual displays in combination with audio signals are adapted to activate stationary, discrete light sources responsive to predetermined parameters of the audio input. Other devices employ electronic circuitry including driver coils and a memory for deflecting a pair of mirrors to direct a reflected light beam to trace predetermined display patterns. Patterns are selected in response to frequency and/or volume characteristics of the audio input signal.
The need remains for a display system for generating novel light patterns traversed on a display surface in response to an audio input signal which are uniquely associated with the input signal.