Analysis of stage lighting technology

Abstract: This paper introduces the development and composition of stage lighting, the structure of stage lighting control system and the location and function of equipment installation, and expounds the relevant technical knowledge in power distribution, control and engineering design of stage lighting.

Keywords: stage lighting, control system, communication module

Since the stage came into being, stage lighting has become an integral part of the stage. Stage lighting focuses on four elements: vision, realism, aesthetics and expression. Has evolved over the years. Gradually developed into a more perfect and advanced lighting system today. The first prosperous period of drama appeared in ancient Greece more than two thousand years ago. The theaters at that time were all open-air or semi-open-air. The lighting of the stage depends on the huge "lamp" in the sky-the sun, so it can only be performed during the day. However, the objective disadvantages such as the need for rest and entertainment at night, the vulnerability of open-air performances to the weather and the development of drama make stage lighting a problem that people must solve.

The success of theater lighting design is marked by the proper handling of stage lighting. Stage lighting should not only illuminate the actors, let the audience see the facial expressions, demeanor and movements clearly, but more importantly, make full use of lighting technology, mobilize lighting operations and other means to enhance the artistic effect, so that the audience has a sense of being there. Installation position, function and lamp configuration of stage lighting According to its use function, stage lighting is mainly divided into two types: dimmable dimming circuit; Non-dimmable direct amplifier circuit. There are three types of stage lighting:

a. General lighting. Refers to the ceiling light and the hanging light ring of the extended stage as part of the ceiling light, as well as the lighting on the grape trellis and the overpass.

b。 Accent lighting. Refers to surface light, slap, column light, side light, foot light, flowing light, low-angle surface light of extended stage, inside (outside) side light, turntable flowing light and low-voltage socket set in the orchestra pit for connecting music lamps.

c。 Decorative lighting. It refers to sky lighting, ground lighting, laser effectors, chasing lights, mobile music fountains and various computer lights used on the stage.

The stage lighting is so important that the above description is relatively simple. Let's analyze it from a technical point of view:

The structure of the stage lighting control system can be roughly divided into three modules; Man-machine interface module, main control module and bottom control module. The three modules communicate with each other by RS485 bus and transmit data at a fixed baud rate.

the function of the man-machine interface module is mainly to receive the control instructions of the controller, which can generally be realized by a simple industrial control panel. After receiving the instruction, the module does not translate the instruction, and directly transmits the key information to the main controller module through RS485 bus.

The main controller is the core part of the whole lighting control system, and is responsible for the connection between the upper control interface and the lower hardware control module. After receiving the key information sent by the control module, the master computer translates it to form a binary control instruction; Then the master computer composes a complete frame of data according to the received instructions and the addresses of related control modules, and transmits it to the downlink bus through RS485 bus, and each bottom control module obtains its own data according to address matching.

The bottom control module is a hardware device that directly controls the action of stage lighting. Because the number of stage lights is generally large, the number of control modules is generally between 11 and 21, and all control modules are linked to the same bus and programmed independently from each other. When the master computer sends data to the bus, all control modules receive the data information, and analyze their own instructions according to the address information contained in the frame structure and execute them.

The control module of the stage lighting control system has two main functions: one is to communicate with the main controller and receive instructions from the upper level. The second is to control the hardware circuit according to the instruction to control the lighting action. The following two modules are introduced respectively.

the following is an introduction to the receiving communication module:

① Selection of communication mode

Because the control signal is relatively simple, serial communication mode is adopted here. This method is convenient to use, and has low requirements for peripheral devices, and the half/full dual-function mode can be freely selected. The most important thing in asynchronous method is the setting of baud rate. Too high, it will increase the burden of single chip microcomputer, or even impossible; Too low will affect the response speed of the whole operation.

② Selection of transmission standards

At present, there are many transmission standards, but each has its own advantages and disadvantages. Because the lighting system is used in the studio, there will be a lot of interference from all kinds of audio and electrical appliances, so the selected transmission mode should be strong in anti-interference. Therefore, when the communication distance is tens of meters to thousands of meters, it is ideal to choose RS485 bus for transmission. The 485 bus uses two transmission lines and adopts balanced transmission and differential reception, so it has the ability to suppress the interference of * * * mode. In addition, the receiver has high sensitivity and can detect the voltage as low as 211mV, so it can greatly enhance the anti-interference ability during transmission, and the transmitted signal can be recovered from thousands of meters away.

RS485 bus is easy to use, and a pair of twisted pairs can be used to realize multi-station networking to form a distributed system. It is widely used in engineering projects because of its simple equipment, low price and long-distance communication.

③ Selection and use of transceiver

The 485 level is transmitted on the 485 bus, while the single chip microcomputer and the main control microcomputer can only recognize the TTL level. In this way, there must be a special chip to design the conversion circuit between the two, which is the transceiver. There are many kinds of transceivers, which can switch different levels as needed. Here, only 485-TTL level switching is needed. Compare-g. M ax48x series and Max148x series with isolation are used. In application, in order to reduce the interference between communication circuit and other circuits, isolation stage is necessary. Although the high-grade 485 transceiver with isolation stage can be directly used, considering the price, it is better to design its own isolation circuit. Here, photoelectric coupling devices and separate power supply are used to realize isolation. When using M ax483, we should pay attention to the control of the enabling terminal. The transceiver is in the receiving state only at/re = 1, and it is portable, avoiding unnecessary repetitive work. The module function management layer and the hardware driver and basic function interface layer in Figure 2 belong to Opentv middleware. The module function management layer is a function about audio, video and channel operation management and control, which is written in accordance with certain middleware function interface standards for the convenience of writing user applications. Driver and basic function interface layer is the bottom part of OpenTV middleware. The software programming at this level should be changed according to the specific hardware drivers, in order to provide a unified driver interface function for the module function management layer.

③ Operating system and hardware driver layer

The operating system adopted in this system is pSOS；; The hardware driver layer mainly provides corresponding drivers for each hardware module. The main drivers include: Kernel module, which is mainly responsible for providing operations on processes, such as the creation and deletion of processes; Interface module, including I C interface operation control, RS-232 serial communication, smart card control, etc. Audio module; Video module; OSD module; Demultiplexing module; Decoding module; Flash driver module; TUNER driver module.

the last step is the debugging of set-top box system: the software of this system is compiled on the basis of pSOS compiler. The whole test block diagram is shown in Figure 3. The system uses a TS code stream generator as the debugging TS source of the set-top box. The TS stream is modulated into the channel by QAM modulator, and the QAM signal is sent to the front end of the set-top box for QAM demodulation, and then sent to the system board for source decoding. The TS stream can also be sent directly through the interface in the system board to debug the source decoding separately. The test of the system PC is carried out on the platform of PC+WINDOWS2111. The running software of the system is executed in the real-time operating system environment of pSOS. The compiled executable file is loaded into the RAM on the hardware platform from the serial port through the emulation RoM, and then the system will read from a fixed address in the RAM and execute the program. Because this hardware platform does not provide a network port, the online debugging function of pSOS cannot be realized, and the debugging information can only be obtained through the output information in the process of executing the program.

Therefore, by connecting the serial port on the hardware with the serial port of the personal computer, the debugging information during the program running can be displayed on the screen of the personal computer, so that the programmer can get the needed debugging information.

[ Summary ]

Nowadays, the control of lighting system has evolved from manual operation to computer control. It also puts forward realistic requirements for the improvement of the computer level of the dancers. I believe that with the continuous improvement of lighting system and the improvement of the quality of dancers, our stage will be more contemporary. More attractive, more exciting.

References:

[1] Li Haidong Building Electricity Science and Technology Press 2112

[2] Jin Changlie, Liu De 'an, Yao Han Stage Lighting Machinery Industry Press 2114

[3] Dou Weiping and Ma Yingjun Visual Design Colors Southeast University Press 2111

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