Light emitting diode (LED) display screen constant current drive circuit with high constant current accuracy

Abstract

The invention discloses a light emitting diode (LED) display screen constant current drive circuit with high constant current accuracy. The LED display screen constant current drive circuit with the high constant current accuracy comprises a reference voltage source circuit, a constant current adjustment circuit, a voltage sampling circuit, a current image ratio self-adjusting circuit, a current mirror circuit and a display frame data processing circuit. The reference voltage source circuit comprises seven-level loop oscillators and a band-gap reference circuit. The voltage sampling circuit comprises a differential comparator and a logic processing circuit. The current image ratio self-adjusting circuit comprises a plurality of logic sum sequence circuits. An output drive channel port of the circuit is provided with a 13V voltage withstanding circuit which comprises two n-metal oxide semiconductor (NMOS) tubes. The constant current adjustment circuit comprises a comparator, a current bias pipe and an external ground resistor. A constant current I0 is adjusted through adjustment of the external ground resistor. The LED display screen constant current drive circuit with the high constant current accuracy has the advantages of being capable of improving constant current accuracy of a chip, capable of increasing LED display screen gray level gradation, capable of improving a luminance contrast degree, capable of achieving voltage withstanding of the output drive channel port with low cost and the like.

Description

[0001] This application is a divisional application with the application number of 201110301641.7, the filing date of September 28, 2011, and the title of the invention "LED display constant current drive circuit with mirror ratio optional". Technical field [0002] The invention relates to a driving circuit, in particular to a constant current driving circuit of an LED display screen with high constant current precision. Background technique [0003] The light emitting diode is a current control device, which has the advantages of high brightness, small size, low power consumption, good monochromaticity, fast response speed, and long service life. Large, medium and small LED display screens are composed of light-emitting diode arrays, which can be used to display text, graphics, images, animations, market quotations, videos and other various information, and light-emitting diodes with three primary colors of red, green and blue The composed full-color LED display can display deli...

AI Technical Summary

Problems solved by technology

However, since the brightness of a light-emitting diode is determined by the current that drives it, the value of M will be restricted by the constant current accuracy of the drive current and the current consistency between different current drive channels, so it is difficult to establish a very accurate more The system of gray level and brightness contrast relationship, which in turn affects the display quality of the entire full-color LED display

[0005] In addition, in order to improve the overall brightness of the LED display and adapt to the environment with strong light, some LED displays will be designed and produced by stringing several LEDs together to increase the brightness, but such a solution will increase the power supply voltage of the entire system At the same time, it is also required that the output drive channel port of the LED drive circuit has the characteristics that the withstand voltage can be improved

In order to make the output drive channel port of the LED drive circuit have the characteristics of improved withstand voltage, the main solution is to use a higher withstand voltage processing technology or use a withstand voltage drive tube for each data output port to drive the LED. string, but both options will increase the cost of the overall system

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