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Moving Head Light Internal Structure and Working Principle
Whether it is a large-scale concert, a variety show, or a small music party, rendering the atmosphere with light effects, highlighting the concept of music expression, creating live effects, has an irreplaceable role. In addition to the traditional downlights, background lights, spotlights, the effect lights have moving head beam lights, LED par lights, gobo moving head lights, as well as wash moving head light, laser light, etc.
Today let's mainly talk about the moving head light. Moving head light is a high-tech product integrating electronics, machinery, and optics. A qualified moving head light must be stable and reliable, with excellent light efficiency, accurate positioning, and good heat dissipation.
The moving head lights can be divided into 200W, 230W, 260W, 280W, 300W, 330W, 350W, 380W, 440W beam moving head lights and other varieties from the use of power. The beam moving head light is the main type of light in professional event venues today.Generally, the moving head light is composed of three major systems: optical, mechanical, electrical, and program control. The three systems are interrelated and organically combined to meet the needs of light, color, gobo, speed, direction, effect, heat dissipation, noise, positioning, and others.
Below let's demystifying the internal structure and working principle of computer lights.
1. Optical system
The most important consideration in optical system design is the luminous flux utilization of the light source. The most important consideration in optical system design is the luminous flux utilization of the light source. Specific performance indicators include light intensity, uniformity, saturation, and spot size.
There are two factors that affect the above indicators, one is the light source, and the other is the optical system structure and material selection.
At present, domestic and foreign manufacturers and users basically recommend YODN, OSRAM, or PHILIPS1200W short-arc double-ended metal gas discharge lamps. Its characteristics are compactness, high brightness, high color temperature, good color rendering, and the light source can maintain a relatively stable color temperature during the dimming process. The disadvantage is that the layering problem of the filler in the lamp, that is, the filler appears in the arc imaging ribbon or condenses in the arc tube, forming a shadow effect, needs to be controlled to the minimum range during the design of the optical structure.
In the optical structure, in order to obtain a uniformly mixed beam, a parabolic reflector can be used. To collect a divergent or narrow beam, a reflector with scale processing or surface texture should be selected. A reflector system made of specular reflective materials is better than a refraction system. When you need to get several beams from a light source, you can use a prism or lens combination refraction system.
Currently, in the optical design of 5R Sharpy Beam/200W beam moving head lights at home and abroad, the lens combination is used, which is composed of aspherical (that is, parabolic) quartz lenses. The most important feature of the parabolic lens is to place a point light source on the focal point, which will get a parallel beam. In the design of the optical path, it is also necessary to consider the correlation between the light intensity distribution curve, shape and the size of the light source, the size of the aperture of the reflective lens, and the shape of the light source.
2. Mechanical system
The range of mechanical systems is very wide, including materials, structure, mechanical properties, housing requirements, heat dissipation requirements, and so on. The main considerations for the selection of moving head lights materials are meeting the functional requirements of the moving head, the degree of difficulty in manufacturing, and the economy. At present, the materials of international and domestic 200W beam moving head lights are mainly steel, plastic, and aluminum alloy. Under the premise of satisfying the overall function of the moving head light, the structural model of the moving light is designed, divided into different parts, and using different materials.
Such as Shining 200W beam moving head light, the arm shell of the lamp body is made of plastic, and the support frame, base, side plate and endplate of the lamp body are made of aluminum alloy castings, stamping parts, and car parts. The structure of the lamp determines its mechanical properties, heat dissipation, strength, noise, weight, and other factors. Both the international and domestic 200W beam moving head light use a dual-arm support structure. The lamp body rotates horizontally up to 540° and vertically rotates up to 270°. The base part must be strengthened to meet the requirements of the hanging head flip. The mechanical properties of the lamp body are mainly reflected in the mechanical strength of the lamp body components so that the lamp body is not deformed, wear-resistant, corrosion-resistant, shock-resistant and pressure-resistant during the continuous and effective working; the lamp housing must have strict waterproof, dustproof, antistatic and moistureproof requirements.
According to the degree of dustproof and waterproof, the protection level requirements of different shells are divided: for example, the protection level of moving head lights used indoors is usually IP20, and the protection level of outdoor moving head lights is usually IP65. For the mechanical structure of 200W high-power moving head lights, the heat dissipation requirements are very important. If the heat dissipation system is defective, it will usually cause electrical parameter drift, color wheel, and gobo wheel rupture, plaques appear, resulting in serious consequences such as crash, out of step, uncontrolled, etc.
3. Electrical and Program Control
First, let's see electrical characteristics and circuit design of moving head light. The vast majority of professional high power moving head lights worldwide use rare gas discharge light sources. The start and stable operation of the gas discharge bubble depend on the design of the circuit type, the selection of electrical components such as power supply, ballast, etc. After the rare gas discharge bulb is started, generally no stabilization time is required. To ensure stability, the difference between the circuit's maintenance voltage and the instantaneous voltage of the bulb should be sufficiently large during the entire AC cycle. For starting, stability, extinction, and restarting of the light source, the circuit should be designed according to the characteristics of the light source. The starting voltage of the rare gas discharge bubble is very high, requiring the use of transformers, starting 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 the current from running out of control and make the light source work under its normal electrical characteristics.
At present, manufacturers usually use two types of ballasts, one is an inductive ballast and the other is an electronic ballast. The advantages of inductive ballast are good stability, and the disadvantages are heavy. They have high requirements for the strength, handling, and loading and unloading of the lamp body. The electronic ballast is essentially power conversion circuits, which carry out the input power current in frequency, waveform, and amplitude. change. Its advantage is lightweight, convenient for loading and unloading, handling. The disadvantage is high structural design requirements and high maintenance costs. A restart of the 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 a vapor pressure resistance. It is difficult to realize the light source to be triggered again immediately. The pressure of the gas in the lamp must be reduced to the cold value Only then can a restart be triggered. At present, international and domestic stage lighting factories basically adopt conventional circuit design.
Second, let's see the program control part of moving head light. Right now, international and domestic moving head lights generally use DMX data format to write program files. The principle of DMX512: The speed of the DMX data stream is 250K, that is, each BIT is a standard 4 microseconds. The data format of DMX is divided into the following parts. 1) IDLE (idle) or NODMXsituation (case): when there is no DMX packet output, it will be a high-level signal. 2) BREAK: The start of the DMX packet is an 88-microsecond low-level output forecast (head). 3) MARKAFTERBREAK (MAB): After MAB is BREAK, it is a high level of 8 microseconds or 2 pulses. 4) START CODE (SC) start code: SC is the channel data at the beginning of the data stream, it 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 second, less than 1 second, MTBF can be high before the start bit of each channel. 6) CHANNEL DATA (CD): the logical format of the channel data frame after SC is 1-512 or less than 512. 7) MARK TIME BETWEENPACKETS (MTBP): Send a high level after the valid data is sent.
The effect of moving head lights is generated by different scenes, color changes, gobos, viewing angles, horizontal and vertical light angle changes and speed, speed, stroboscopic speed, aperture size change, focal length change, and other comprehensive performance. The work of all these attribute indexes is realized by the transmission of the stepper motor. The electrical operating parameters of the stepper motor are defined and programmed, and the control of the moving head light is completed.
All in all, today we learn about the moving head light internal structure and working principle. I hope you have a more clear mind about stage lighting moving head light now.
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