LED digital tube display use the drive circuit to drive the digital tube segment, which shows what we want, therefore, according to the different ways on the drive LED digital tube can be divided into static and dynamic categories .
A, static display driver:
Static drive, also known as the DC drive. Static drive means to each tube for each segment of code consists of a microcontroller I / O ports to drive, or use, such as BCD code – decimal decoder decoding to drive. The advantages of the static drive is programmed, the display brightness, the drawback is that takes up I / O ports and more, such as driving the 5 digit tube (stealth led grow lights) static display, 5 × 8 = 40 I / O port to drive, be aware that a 89S51 microcontroller available the I / O port 32. Must be increased so the practical application of the decode drive to drive, increasing the complexity of the hardware circuit.
B, dynamic display driver:
Digital dynamic display interface is one of the most widely used microcontroller, a display, dynamic driving the all digital tube (stealth led grow lights) 8 shows the stroke “a, b, c, d, e, f, g, dp” with the same name connected together, the other to increase the bit strobe control circuit for each of the tube very COM-bit strobe controlled by a separate I / O lines, when the microcontroller output glyph code, all digital tube received the same font code, but what is the digital tube will display the shape, depending on the control of the microcontroller strobe bit COM terminal circuit, so we just need to display digital tube strobe control open, the bit on the show the glyph, there is no digital strobe tube will not light.
Through time-sharing in turn control the COM side of each LED digital tube, so that in turn controlled display various digital tube, which is dynamically driven. In the rotation display process, per bit digital tube light time of 2ms, the human visual persistence of the phenomenon and the light-emitting diode (stealth led grow lights) afterglow effect, despite the fact that you number the pipe is not lit, but as long as the sweep The aim of speed is fast enough to create the impression that a stable set of display data, there will be no light flashes, the effect of dynamic display and static display is the same, can save a lot of I / O port, and lower power consumption.
Constant current driver with constant current driver on the LED digital tube is mainly the following:
1, showing the effect:
LED tube is basically a current sensitive components, the dispersion of the forward voltage drop large, and also with the temperature, you need to make it a constant current in order to ensure digital pipe has good brightness uniformity, and can not be temperature and other factors. In addition, when the temperature changes when the driver chips also can automatically adjust the size of the output current in order to achieve the temperature compensation of the color balance.
2, security:
Even short-term current overload may also cause permanent damage to the LED lights, digital tube, constant current drive circuit to prevent current fault extensive damage.
In addition, the Commission adopted VLSI characteristics of cascading delay switch to prevent reverse voltage spike damage on the light-emitting diode. VLSI also has thermal protection which automatically shuts down when any one temperature exceeds a certain value, fault indication and can be seen in the control room.