1, Electrical Characteristics and Circuit Design of Computer Moving Head Lamps

Before, the vast majority of professional 1200W moving head computer lamps worldwide used rare gas discharge bulb light sources. The starting and stable operation of the gas discharge bubble depends on the design of the circuit type, the choice of electrical components such as power supply and ballast. After the rare gas discharge bulb is started, generally no stabilization time is required. In order to ensure stabilization, the difference between the maintaining voltage of the circuit and the instantaneous voltage of the bulb should be sufficiently large during the entire AC cycle. The starting, stability, extinguishing and restarting of

light source should be designed according to the characteristics of the light source. The starting voltage of the rare gas discharge bubble is very high, which requires the use of transformers, starter devices, semi-resonant circuits, etc., to increase the instantaneous starting voltage. The stability of the light source after starting depends on the matching of ballast and circuit parameters. The basic function of the ballast is to prevent current runaway and to operate the light source under its normal electrical characteristics. At present, manufacturers usually use two types of ballasts, one is an inductive rectifier and the other is an electronic rectifier. The advantage of inductive rectifier is good stability, the disadvantage is heavy, the strength of the lamp body, handling, loading and unloading have higher requirements; electronic rectifier is essentially a power conversion circuit, the input power current frequency, waveform and amplitude changes. Its advantages are light weight, convenient loading and unloading, and handling; the disadvantages are high structural design requirements and high maintenance costs. The restart of

light source, in the conventional circuit design, due to the high temperature generated during the operation of the gas discharge bubble, the saturated gas in the bubble forms vapor pressure resistance, it is difficult to realize the immediate retrigger of the light source, and the restart can only be triggered after the gas pressure in the lamp is reduced to the cold state value. At present, international and domestic production enterprises basically adopt conventional circuit design.

2, Program Control Part

At present, international and domestic computer lights generally use DMX data format to write program files. Principle of DMX512: The speed of DMX data stream is 250K, that is, each BIT is 4 microseconds of standard. The data format of DMX is divided into the following parts: 1)IDLE (idle) or NO DMX situation (case): when there is no DMX data packet output, it will be a high level signal; 2)BREAK: The beginning of DMX data packet is a forecast {header} of 88 microseconds low level output; 3)MARK AFTER BREAK(MAB):MAB is after BREAK, is an 8 microsecond high level or 2 pulses; 4)STARTCODE(SC) start code: SC is the channel data at the beginning of the data stream, which has the same format as the channel data, generally 11 pulses or 44 microseconds; 5)MARK TIME BETWEEN FRAMES(MTBF):MTBF can be 0-1 seconds, less than 1 second, and MTBF can be high level before each channel start bit, which is; 6)CHANNEL DATA(CD): The logical format of the channel data frame after SC is 1-512 or less than 512;7)MARK TIME BETWEEN PACKETS(MTBP): Send high level after valid data is sent.

computer light effect is produced through different modeling scenes, different color changes, different viewing angles, horizontal and vertical light angle changes, speed, strobe speed, aperture size changes, focal length changes and other comprehensive performance. The work of all these attribute indexes is realized by the drive of the stepper motor, and the electrical operation parameters of the stepper motor are defined and programmed to complete the control of the computer lamp.