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Light term explanation

Light term explanation

(Summary description)Brightness refers to the luminous intensity emitted in a given direction around a micro-unit area on a surface divided by the area of the unit projected in the same direction, the unit is: cd/c㎡. The concept of brightness is generally not encountered in a lighting system.

Light term explanation

(Summary description)Brightness refers to the luminous intensity emitted in a given direction around a micro-unit area on a surface divided by the area of the unit projected in the same direction, the unit is: cd/c㎡. The concept of brightness is generally not encountered in a lighting system.


1. Brightness

   Brightness refers to the luminous intensity emitted in a given direction around a micro-unit area on a surface divided by the area of ​​the unit projected in the same direction, the unit is: cd/c㎡. The concept of brightness is generally not encountered in a lighting system.

2. Illumination

   Illuminance refers to the luminous flux density on a surface, it is the luminous flux incident on 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 construction and decoration engineering, and occasionally the concept of illuminance is also involved in the lighting system.

3. Luminous flux

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

4. Color temperature

   color temperature refers to 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 as the unit. For example, 3200k and 5600k, etc. The color temperature is high, and the color of the light is cold: the color temperature is low, and the color of the light is warm: 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 lamps for studios and performances is about 3200k (heat light source). However, the recent emergence of cold light source lighting in TV studios is a revolution to traditional light sources. The cold light source has high color temperature, low energy consumption and low heat generation. When performing indoor and outdoor photography, the color temperature conversion is simple and the picture is natural. Of course, the cold light source also requires higher performance requirements for the dimming table.

5. Channel

  In modern light control, a new concept of channel is produced. It refers to a collection of control loops on a certain lamp. Specifically, the function of a certain lamp needs to be controlled separately (for example: focusing, strobe, color change, etc.), and the collective name of the output circuit of the dimmer that it occupies is the channel. For example, the functions of a computer light include aperture, color, strobe, dimming, horizontal movement and vertical movement of the lens, so that they occupy 6 channels. It can be seen from this that the concept of channel is still evolved from the traditional lighting control loop, but modern lamps and lanterns are unified and controlled by combining multiple channels on one device. Of course, the more advanced, complicated, and more actions the lamps are, the more channels may be occupied, and the higher the requirements for the lighting console. For example, if a dimming console with 108 light paths and digital output wants to control a computer light with 12 channels, then it can only control 9 such lamps at most. How to control it is a matter of signal and address allocation. Up.

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 analog control signal. It is usually used in stage dimming, speed control and the control of some simple effect lamps. Its advantage is: signal generation, reception and processing are relatively simple. There is no need to add any processing equipment, it is intuitive to use and easy to maintain. 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 need to be controlled by a dedicated person, so they are generally controlled by analog signals. Its shortcomings are: signal transmission is more troublesome, and each loop must have a separate signal path. This is why the signal input interface is thick and large on analog control equipment with more signal channels (in it There are dozens or hundreds of ferrules); at the same time, the anti-interference ability of analog signals is 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 it can quickly and accurately transmit dozens or hundreds of optical path information to the corresponding equipment with a single signal line, and the transmission distance is very long, and the anti-interference is high. The same type of digital control signal can also be used. It is easy to combine with each other. Its shortcomings are: the corresponding coding and receiving equipment are more complicated, and under the existing technical conditions (coding and processing technology), the information it can hold is still limited. There are two commonly used digital control signals:

1) lRS232 digital signal (also known as PMX)

   It is a serial digital coded signal, introduced by the British pulsar company. Generally use 3-core or 5-core XLR plug-in interface, where 1 is the shielding ground, 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 digital coded signal. Due to its wider application range, it has gradually become a standard for light control signals. With the existing transmission ratio and signal processing capabilities, it can transmit the output signal of the optical path to 512 optical paths. When using DMX512 digital signal, in order to ensure the accuracy of signal transmission, it is necessary to use a terminating resistor at the end of the signal line.

3) Address coding

  Address coding is a concept that is generated simultaneously with the digital control signal. It refers to the determination of lamps or other light driving equipment in a specific position controlled by digital signals, that is to say: in the signal control system of the light equipment, they are given a number similar to the address. The address code can express the actual position of the lamp in the system, that is, the real address code: it can also express the starting position of the channel contained in the lamp in the system. To be precise, the address at this time should be the limbs of the channel. Usually, the address encoding is done by an address encoder, and usually multiple two-stage DIP switches on the address encoder are used to set the address. For the address coding, it is necessary to clearly point out that: the consecutive numbers of 1, 2, 3, 4, etc. on the general address encoder refer to the number of the DIP switch of the encoder, rather than the real address encoding. The difference between the address code and the DIP switch value is easier to understand. Because the digital signal adopts the binary coding method, the address coding also incorporates this idea. It uses the corresponding DIP switch to turn on and off to achieve the purpose of digital coding. in fact. The address code corresponding to the Nth DIP switch is regular, that is, 2n-1, which is the exponential form of 2. In addition, the address code is in the form of the sum of the address codes corresponding to the DIP switch. For example, the address code corresponding to the above address encoder should be 1+4+8=13, which means that the address code is set to the 13th fixture of the system or the 13th channel in the system. If the device includes multiple channels, then its DIP switch setting is the address code of its first channel, and the subsequent channels are arranged in sequence. For example: the device has 12 channels, and the address set by its DIP switch is 13, so the channel address occupied by the device in the system is from 13-24.

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