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Explanation of terms related to stage lighting

StaJim Knowledge Sep 13,2022 04:37 126 0

Some knowledge about: color temperature channel luminous flux, etc.
1. Brightness 
Brightness refers to the luminous intensity emitted in a given direction divided by the area of ​​the unit projected in the same direction around a point of micro-unit area on a surface, the unit is: cd/c㎡. The concept of brightness is generally not encountered in lighting systems. 

2. Illumination 
Illuminance refers to the luminous flux density on one surface, which is the luminous flux entering a unit area, and the unit is LX. The definition and measurement of illuminance are more complicated, such as average cylindrical illuminance, equivalent spherical illuminance, scalar illuminance, etc. Their measurement conditions and calculation methods are different. It is often encountered in architectural and decorative projects, and the concept of illuminance is occasionally involved in lighting systems. 

3. Luminous flux 
Luminous flux refers to the energy radiated from the light source to the surrounding space per unit time, which can cause visual response energy, that is, the energy of visible light. It describes the effective radiation value of the light source in 1m (lumens). The luminous flux of lamps of the same power may be completely different because of their different luminous efficacy. For example: ordinary lighting bulbs are only 10 1m/W, while metal halide lamps can reach 80 1m/W. 

4. Color temperature 
Color temperature means that when the color emitted by the light source is the same as the light color radiated by the black body at a certain temperature, the temperature of the black body is called the color temperature of the light source, generally in Kelvin k. Such as 3200k and 5600k and so on. When the color temperature is high, the color of the light is cooler: when the color temperature is low, the color of the light is warmer: when the color temperature is moderate, the light is close to white. Under normal sunlight in nature, the color temperature of light is generally higher than that of artificial lamps. Under normal circumstances, the color temperature of sunlight is about 5600k, while the color temperature of studio and performance lamps is about 3200k (thermal light source). However, the recent rise of cold light source lighting in TV studios is a change to traditional light sources. The color temperature of the cold light source is high, the energy consumption is low, and the heat generation is small. When shooting indoors and outdoors, the color temperature conversion is simple, and the picture is natural. Of course, the performance requirements of the cold light source on the dimming table are also higher. 

5. Channel 
In modern light control, a new concept of a channel arises. It refers to a collection of control loops on a luminaire. Specifically, the functions of a certain lamp need to be controlled separately (such as: focus, strobe, color change, etc.), and the collective name of the output circuit of the dimmer console is the channel. For example, the functions of a computer light include aperture, color, strobe, dimming, horizontal movement of the lens, and vertical movement, so they occupy 6 channels. It can be seen from this that the concept of the channel is still evolved from the traditional lighting control loop, but modern lighting is a collection of multiple channels on one device for unified control. Of course, the more advanced, more complex, and the more actions the lamps and lanterns have, the more channels they may occupy, and the higher the requirements for the lighting console. For example: a dimmer with 108 light paths and digital output, if it wants to control a computer light with 12 channels, it can only control 9 such lights at most, how to control it is a problem of signal and address allocation .

6. Analog control signal 
It is a signal that directly uses low-voltage signals to control lamps or silicon boxes. Now generally 0~10V voltage signal is used as an analog control signal. It is usually used in stage dimming, speed regulation and control of some simple effect lamps. Its advantages are: the generation, reception and processing of signals are relatively simple. There is no need to add any processing equipment, the use is intuitive, and the maintenance is relatively easy. Especially in dimming control, the analog control signal can easily achieve stepless dimming. In some important places, due to the consideration of reliability, some computer lamps and lanterns are generally controlled by analog signals because they need to be controlled by special personnel. Its disadvantage is that the signal transmission is more troublesome, and each loop must have a separate signal path, which is why the signal input interface of the analog control device with many signal channels is thick and large (in it There are dozens or hundreds of ferrules); at the same time, the anti-interference ability of analog signals is also relatively poor. 

7. Digital control signal 
It uses digitally encoded bit signals to control information (including parameters and addresses), including a multi-data control signal, which is usually used in modern computer lamps and digital control equipment. Its biggest advantage is that dozens or hundreds of optical path information can be quickly and accurately transmitted to the corresponding equipment with one signal line, and the transmission distance is very long, the anti-interference is high, and the same type of digital control signal can also be used. It's easy to combine with each other. Its disadvantage is that the corresponding coding and receiving equipment are complicated, and under the existing technical conditions (coding and processing technology), the information it can accommodate is still limited. There are two types of digital control signals commonly used: 
 1) lRS232 digital signal (aka PMX) 
 It is a serial digital coded signal, introduced by the British pulsar company. Generally, a 3-pin or 5-pin XLR socket is used, of which 1 is the shielding ground, and 2 and 3 are the signal paths. This signal is mainly used in the pulsar console and the lamps and silicon boxes that receive this signal. 
 2) DMX512 digital signal 
 It is also a serial digitally encoded signal. Due to its wider and wider range of use, it has gradually become a standard for light control signals. With the existing transmission ratio and signal processing capability, it can transmit the optical output signal to 512 optical paths. When using DMX512 digital signals, in order to ensure accurate signal transmission, it is necessary to use a terminating resistor at the end of the signal line. 
 3) Address encoding 
 Address coding is a concept that occurs simultaneously with digital control signals.
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