The organic electroluminescent (EL) devices, also known as organic light emitting diode (O LED) generally has a layer structure of organic electroluminescent medium between a metallic cathode and a transparent anode gripper. After a certain voltage is applied between the electrodes, the luminescent medium emits light. A display made by applying an OLED to a flat panel display is called an organic light emitting display, also called an OLED display. Compared with LCD, OLED has active illumination, no viewing angle problem; light weight, small thickness; high brightness, high luminous efficiency; rich luminescent materials, easy to realize color display; fast response, high dynamic picture quality; wide temperature range; It can realize soft display; it has a series of advantages such as simple process, low cost and strong seismic resistance, so he is called the ideal display of the future by experts.
Although OLED has made great progress and has brought new dawn to the field of flat panel display, O LED technology is still in the development stage, and organic luminescent materials are still the most important limiting factor of OLED. Since the microscopic world of organic electroluminescence is difficult to directly observe, it can only provide a certain basis for analyzing the luminescence mechanism by measuring the driving voltage, current, brightness, luminous efficiency and other parameter indicators. The key content of this paper is the use of single-chip control and power conversion technology, using a self-designed drive power with adjustable voltage, frequency and duty cycle as a test platform for analyzing organic electroluminescent materials, and designing voltage, Different software modules such as real-time frequency adjustment enable the power supply to work in different driving modes, and achieve performance testing of cold light sheets (organic electroluminescent media) in different states.
2, test power hardware structure
The test power supply used in this paper is an AC pulse power supply, which is divided into two parts from the circuit function: main circuit and auxiliary circuit.
The main circuit includes: chopper voltage regulation and full-bridge conversion circuit to generate AC pulse voltage with adjustable peak voltage, frequency and duty cycle.
The auxiliary circuit includes the following parts:
(1) The control circuit realizes the generation of the control signals of the chopper tube and the frequency modulation tube, and has the functions of overcurrent protection interruption, A/D sampling of the potentiometer setting value and manual reset.
(2) The driving circuit provides power amplification of the pulse signal generated by the control circuit to each of the switching tubes, and simultaneously isolates the main circuit from the control circuit.
(3) The snubber circuit reduces the power consumption of each switch tube at the moment of switching, and improves the safety of the switch tube at the moment of switching.
(4) Over-current protection circuit to prevent the transient current from being too large when the load is short-circuited, and damage the components.
(5) The peak voltage sampling circuit provides a peak voltage sample value in the range of 0 to 5 V for the display circuit.
(6) Auxiliary power supply to supply power to the control circuit, drive circuit and display circuit. The circuit block diagram of the power supply is shown in Figure 1.
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