High intensity lighting circuit

#The present invention relates to the production of high levels of intense light, e.g. 25 kw-1000 kw, having applications in numerous fields, such as flash photography, solid state laser pumps, entertainment special effects, stroboscopes, and solar flash simulators.

#In the application to which the present invention is particularly directed, entertainment special effects lighting, high intensity light to simulate lightning, for example, was initially produced by drawing an arc between carbon electrodes connected in a high voltage DC circuit. With the advent of high intensity lamps, such as xenon lamps, drive circuits were developed to drive these lamps in a pulsed mode to produce bursts of high intensity simulating lightning bolts. As exemplified by Pringle et al., U.S. Pat. No. 5,150,012, such drive circuits have been AC drive circuits. To achieve pulsed operation, high power AC switches, such as triacs, are required. Triacs, while capable of handling the high levels of voltage and current involved, are notorious radiators of EMI (electromagnetic interference), which raises havoc with any associated electronic equipment. Triacs also produce undesirable AC waveform distortion.

#It is an objective of the present invention to overcome at least some of the disadvantages and drawbacks of the prior art. To achieve this objective, in accordance with the present invention, there is provided a high intensity lighting circuit comprising a circuit breaker having three phase inputs for connection to a three phase AC source and three phase outputs connected to inputs of a three phase full wave rectifying bridge network having first and second DC output terminals. A high intensity DC lamp has a first electrode connected to the first DC output terminal and a second electrode connected to the second DC output terminal through an ignitor having power inputs connected to at least one of the three phase outputs of the circuit breaker.

#The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the following detailed description, serve to explain the objectives, advantages, and principles of the invention.

#The sole FIGURE of the drawing is a circuit diagram of a high intensity lighting circuit in accordance with a presently preferred embodiment of the present invention.

#A high intensity lighting circuit consistent with the present invention, as illustrated in the drawing, includes a three phase circuit breaker 10 connected to a three phase AC source 12, which may have an output voltage of, for example, 208, 240, or 480 volts. This circuit breaker would typically be equipped to provide overcurrent protection. When circuit breaker 10 is closed, the three phases A, B, and C of source 12 are rectified by a full wave bridge network, generally indicated at 14, to produce a positive DC output voltage on terminal 16 and a negative DC output voltage on terminal 18.

#The positive bridge output terminal 16 is connected to one electrode 22 of a DC xenon lamp 24, while negative bridge output terminal 18 is connected to the other electrode 26 of the xenon lamp through an ignitor 28 and a single pole electronically controlled switch, such as a solid state relay 30. This solid state relay may be an insulated gate, bipolar transistor DC power switch, and thus avoids the drawback of triacs. A solid state relay suitable for application in the present invention is commercially available from Gentron of Scottsdale, Ariz. under the designation IGTD 600240R100.

#An ignitor 28 suitable for application in the present invention is a Model 4675 manufactured by L.P. Associates of Hollywood, Calif. The AC power input for ignitor 28 is obtained from two of the three phase outputs of circuit breaker 10 through a two pole relay 32, which may be a conventional electromagnetic relay. A current limiting resistor R1 may be connected into the ignitor power input circuit.