The computer shake head lamp is a high-tech product that integrates electronics, mechanics, and optics. A qualified computer shaking head lamp must be stable and reliable, with excellent light efficiency, accurate positioning, good heat dissipation, and the lamp body and material structure must meet the requirements of human-machine engineering. Computer shake head lights can be classified into 250W, 575W, 1200W and other types based on their power usage. Among them, 1200W is the main lighting type for professional performance venues. This article focuses on analyzing the construction principle of the 1200W shaking head lamp. In summary, the shaking head computer light is composed of three major systems: optical, mechanical, electrical, and program control. The three major systems are interrelated and organically combined to meet the needs of elements such as light, color, speed, direction, effect, heat dissipation, noise, and positioning.
1、 Optical system
The main consideration in optical system design is the utilization rate of light source flux. 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 generally recommend OSRAM or PHILIPS 1200W short arc double ended metal gas discharge lamps. Its characteristics include compactness, high brightness, high color temperature, good color rendering, and the ability of the light source to maintain a relatively stable color temperature during dimming. The disadvantage is that the layering problem of the filling agent inside the lamp tube, that is, the filling agent appears as a color band in arc imaging or condenses in the arc tube, forming a shadow effect, needs to be controlled within the minimum range during optical structure design. In optical structures, to obtain a uniform mixed beam, a parabolic reflector can be used. To collect divergent or narrow beams, a reflector with scale processing or surface texture should be selected. A reflector system made of mirror reflective materials is better than a refracting system. When several beams of light need to be obtained from a single light source, a prism or lens combination refractive system can be used. At present, the optical design of 1200W shaking head computer lights both domestically and internationally adopts a lens combination method, consisting of non spherical (i.e. parabolic) quartz lenses, etc.
The most important feature of a parabolic lens is to place a point light source at the focal point, which will result in a parallel beam of light. When designing the optical path, it is also necessary to consider the correlation between the intensity distribution curve, shape and the size of the light source, the aperture size of the reflective lens, and the shape of the light source.
2、 Mechanical systems
The scope of mechanical systems is very wide, including materials, structure, mechanical performance, shell requirements, heat dissipation requirements, and so on. The main factors to consider in the selection of lighting materials include meeting the functional requirements of the lamp, the difficulty of manufacturing, and the economy. At present, the materials for international and domestic 1200W shaking head lamps mainly include steel, plastic, and aluminum alloy. Under the premise of considering meeting the overall function of the lamp, design the structural model of the lamp, divide it into different parts, and use different materials. For example, Aceda spot 1200III1200W shaking head lamp, the lamp body shell is made of plastic parts, and the lamp body support frame, base, side plate, and end plate are made of aluminum alloy castings, stamped parts, and car parts.
The structure of a lamp determines its mechanical performance, heat dissipation, strength, noise, weight, and other factors. Both international and domestic 1200W shaking head lamps adopt a double arm support structure, with the lamp body rotating horizontally up to 540 ° and vertically up to 255 °. The base part needs to be reinforced to meet the hanging and inversion requirements of the shaking head lamp.
The mechanical performance of the lamp body is mainly reflected in the mechanical strength of the lamp body components, which enables the lamp body to work continuously and effectively without deformation, wear resistance, corrosion resistance, earthquake resistance, and compression resistance; The shell of the lamp must have strict requirements for waterproofing, dust-proof, anti-static, and moisture-proof. According to the degree of dust and water resistance, the protection level requirements for different casings are divided: for example, the protection level for indoor computer lights is usually IP20, and the protection level for outdoor computer lights is usually IP44.
The mechanical structure of a 1200W high-power computer light requires crucial heat dissipation. If there is a defect in the heat dissipation system, it usually causes electrical parameter drift, color chip and film breakage, plaque formation, and serious consequences such as crashing, losing step, and being out of control.
3、 Electrical and Program Control Section
1. Electrical characteristics and circuit design of computer shaking head lights
Most professional 1200W shaking head computer lights worldwide use rare gas discharge bubble light sources. The start-up and stable operation of gas discharge bubbles depend on the design of the circuit type, the selection of electrical components such as power supply and ballast. After starting the rare gas discharge bubble, it generally does not require a stable time. To ensure stability, the difference between the maintained voltage of the circuit and the instantaneous voltage of the light bulb should be sufficiently large throughout the entire AC cycle.
The starting, stability, extinguishing, and restarting of the light source should be designed according to the characteristics of the light source. The starting voltage of rare gas discharge bubbles is very high, requiring the use of transformers, starting devices, semi resonant circuits, and other methods to increase the instantaneous starting voltage. The stability of the light source after starting depends on the matching of the ballast and circuit parameters. The basic function of a ballast is to prevent current loss of control and ensure that the light source operates under its normal electrical characteristics. At present, production enterprises usually use two types of ballasts, one is an inductive rectifier and the other is an electronic rectifier. The advantage of an inductive rectifier is good stability, but the disadvantage is heavy weight, which requires high requirements for the strength, handling, and loading and unloading of the lamp body; Electronic rectifiers are essentially power conversion circuits that change the frequency, waveform, and amplitude of the input power current. Its advantages are light weight, convenient for loading, unloading, and transportation; The disadvantage is high structural design requirements and high maintenance costs.
The restart of the light source is difficult to achieve immediately due to the high temperature generated during the operation of the gas discharge bubble in conventional circuit design, which causes the saturated gas inside the bubble to form vapor pressure resistance. It is necessary to reduce the gas pressure inside the lamp to a cold state value before triggering the restart. At present, international and domestic production enterprises generally adopt conventional circuit design.
2. Program Control Section
At present, both international and domestic computer lights generally use the data format of DMA to write program files. The principle of DMX512: The speed of the DMX512 data stream is 250K, which means each BIT is a standard 4 microseconds. The data format of DMA is divided into the following parts: 1) IDLE (idle) or NO DMA situation: When there is no DMA data packet output, it will be a high-level signal; 2) BREAK: The beginning of the DMA packet is a low-level output prediction header of 88 microseconds; 3) MARK After BREAK (MAB): MAB is a high level of 8 microseconds or 2 pulses after the BREAK; 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, usually 11 pulses or 44 microseconds; 5) MARK TIME BETWEEN Frames (MTBF): The MTBF can be 0-1 seconds, less than 1 second, and can be set as 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 BETWEEN PACKETS (MTBP): Send a high level signal after sending valid data.
The effect of computer lights is generated through different shaped scenes, different color changes, different angles of view, horizontal and vertical light angles, as well as comprehensive expressions such as speed, strobe, aperture size, and focal length changes. All these attribute indicators are achieved through the transmission of the stepper motor. By defining and programming the electrical operating parameters of the stepper motor, the control of the computer light is completed.
