The gray scale referred to in the
LED display industry can also be referred to as LED brightness. Gray level is also called midtone. It is mainly used to transmit images, pictures, and video screens. There are 16 levels, 32 levels, and 64 levels. It uses matrix processing to process the pixels of the file into 16, 32, and 64 levels. To make the transmitted picture clearer. Whether it is a full-color screen or a two-color screen, it is necessary to adjust the illuminance of each LED constituting a pixel to display an image or an animation, and the degree of fineness of the adjustment is what we usually call gradation.
The main control box obtains the brightness data of each layer of pixels from the display card of the computer, and then re-allocates the data to a plurality of scanning boards, each of which is responsible for controlling several rows (columns) on the LED screen, and each row (column) The display control signals of the upper LEDs are transmitted in a serial manner.
There are currently two ways to serially transmit display control signals:
First, pulse width modulation. The serial transmission of the scan board is not the switching signal of each LED but an 8-bit binary gray value. Each LED has its own pulse width modulator to control the lighting time. Thus, in a period of repeated lighting, each pixel point requires only 4 pulses in 16-level gray scale, and only 8 pulses in 256-level gray scale, which greatly reduces the serial transmission frequency. With this method of controlling the gradation of the LED, it is convenient to implement 256-level gradation control.
Second, the scanning board centrally controls the gray level of each pixel, the scanning board decomposes the gray value of each row of pixels from the control box (ie, pulse width modulation), and then turns the turn-on signal of each row of LEDs into a pulse form (lighting It is 1, and it is not lit. 0) It is serially transmitted to the corresponding LED by line to control whether it is lit. This method uses fewer devices, but the amount of data transmitted serially is larger because each pixel requires 16 pulses at 16 levels of gray during a repeated lighting period, requiring 256 levels of gray. 256 pulses, due to the device operating frequency limit, generally only enable the LED screen to achieve 16 gray levels.
There are two ways to control the gray level of the LED:
First, change the current flowing.
Second, pulse width modulation:
1) Change the current flowing through the LED. Generally, the LED tube allows a continuous operating current of about 20 mA. In addition to the saturation of the red LED, the other LED gray levels are substantially proportional to the current flowing through;
2) Using the visual inertia of the human eye, the pulse width modulation method is used to realize the gray scale control, that is, the optical pulse width (ie, the duty ratio) is periodically changed, as long as the period of repeated lighting is short enough (ie, the refresh frequency is sufficiently high) ), the human eye does not feel that the illuminating pixels are shaking. Because pulse width modulation is more suitable for digital control.
Therefore, in today's widespread use of microcomputers to provide LED display content, almost all LED screens use pulse width modulation to control gray levels. The LED control system usually consists of three main parts: the main control box, the scanning board and the display control unit.
Stator Interlocking
Progressive Punching is an efficient self-riveting process of fixed rotor, which can realize large-scale and precise riveting operation and is suitable for mass manufacturing production line. The following is the introduction of progressive rotor self-riveting process:
First, determine the type and specification of the stator and rotor required for riveting, and prepare the rivets and riveting machines required for riveting. Rivet size should match the hole size of stator and rotor to ensure tight fit and firmness.
According to the size and riveting requirements of stator and rotor, the rivet is machined into the corresponding length and shape. Progressive punch riveting machine also needs to adjust, set, calibrate the position of the riveting head, pressure, speed and other parameters.
Insert the rivet into the stator hole, and start the progressive punching riveting machine with electricity. The rivet will exert force on the rivet head according to the set parameters, and form a large number of threaded processes on the inner wall of the stator hole, so that the rivet deformation is firmly connected with the stator.
Wait for the rivet deformation, riveting process is complete. The remaining rivet tail should be cut off and inspected after riveting is completed to ensure that the riveting is firm and reliable and the transmission system runs smoothly.
In general, the process of progressive impact fixed rotor self-riveting can improve the production efficiency, but also ensure the precision and stability of riveting. However, riveting machine adjustment requires specialized skills, so an operator familiar with the riveting process is required.
Motor stator riveting, beraring stator riveting, generator stator riveting
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