Testing Scheme for White Radiation OLED-matrix
DOI:
https://doi.org/10.31649/1997-9266-2020-153-6-115-120Keywords:
OLED-matrix, LED, test circuit, microcontrollerAbstract
The scheme of testing the organic LED-matrix is proposed, the size of which is 16´16 tricolour pixels, the voltage control range is 5…30 mA, the supply voltage has 16 discrete values that vary in the range from 2 to 6 V in steps of 0,25 V. The purpose of the device for which the scheme is developed is to study the reliability of the failure time in different modes of operation, dynamic and electrical characteristics in the range of the device, which is determined by the condition that the loss of luminosity is from 100 to 70 %.
The proposed testing scheme is designed on two boards (two modules) for flexible upgrades if necessary.
The main module is the controller of the LED panel. It is built on an eight-bit ATMega8515 microcontroller. Since the size of the test field of the panel is small, the speed of such a microcontroller is quite sufficient. The microcontroller dynamically controls the display driver, display voltage, and communicates with the computer via the USART interface using a USB-USART bus converter. The microcontroller's internal random access memory (RAM) is insufficient, so the data for display on the display panel is stored in the external memory type SRAM, which is connected to the microcontroller.
The slave module is the driver board of the LED matrix. The LEDs are powered by a separate adjustable voltage source, which additionally allows you to adjust the overall brightness of the display, explore its operation in different ranges of supply voltages, extend the service life during operation. Switching of supply voltage on lines is carried out through electronic keys on the TD62783 chip. The matrix row is selected by a 4-on-16 decoder 74HC4514.
To control the brightness of the LEDs on the columns used specialized chips WS2801. They provide bit control of 8 bits per color, a total of 24 bits, which is more than 16 million shades. The two-wire data recording circuit and the possibility of cascading reduces the number of wires in the circuit. The ability to connect reverse resistors (RFB, GFB, BFB) to the current stabilizer of the LED, allows you to compensate for the variance of the parameters of the LED matrix by selecting the values of these resistors.
A special power supply module provides stabilization of supply voltages of digital chips and LED matrix
References
Tetsuo Urabe et al., “Technological Evolution for Large Screen Size Active Matrix OLED Display,” SID, vol. 38, issue 1, pp.161-164. May, 2007. [Electronic resource]. Available: https://onlinelibrary.wiley.com/doi/abs/10.1889/1.2785252 .
Min-Hao Michael Lu et al., “Power Consumption and Temperature Increase in Large Area Active-Matrix OLED Displays,” Journal of Display Technology, vol. 4, issue 1, pp. 47-53, 2008. https://www.osapublishing.org/jdt/abstract.cfm?uri=jdt-4-1-47 .
Inseok Choi et al., “Low-power color TFT LCD display for hand-held embedded systems,” in ISLPED '02 Proceedings of the 2002 international symposium on Low power electronics and design. Monterey, California, USA: Association for Computing Machinery, August 2002, pp.112-117. [Electronic resource]. Available: https://dl.acm.org/doi/abs/10.1145/566408.566440 .
Bernard Geffroy et al. “Organic light-emitting diode (OLED) technology: materials, devices and display technologies,” Polymer international, vol. 55, issue 6, pp. 572-582, February, 2006. [Electronic resource]. Available: https://onlinelibrary.wiley.com/doi/abs/10.1002/pi.1974 .
А. Самарин, «OLEDD дисплеи: от мифов к реальности,» Компоненты и технологии, № 2, 2007. [Электронный ресурс]. Режим доступа: https://ecworld.ru/media/bip/pdfs/samarin_ct207.pdf .
Preliminary WS2801 3-Channel Constant Current LED Driver With Programmable PWM Outputs. [Online]. Available: https://pdf1.alldatasheet.com/datasheet-pdf/view/1132047/ETC1/WS2801.html .
High-Speed CMOS Logic 4- to 16-Line Decoder/Demultiplexer with Input Latches. [Online]. Available: http://www.ti.com/lit/ds/symlink/cd54hc4514.pdf .
8ch High-Voltage Source Driver. [Online]. Available: https://docs.rs-online.com/bc35/0900766b80811071.pdf .
ATmega8515. 8-bit Microcontroller with 8K Bytes In-System Programmable Flash. [Online]. Available: http://ww1.microchip.com/downloads/en/devicedoc/doc2512.pdf .
CY7C199. 32K x 8 Static RAM. [Online]. Available: http://info.incomp.hu/NETPDF/CY7C199-25SC.pdf .
CD54HC573, CD74HC573 OCTAL TRANSPARENT D-TYPE LATCHES WITH 3-STATE OUTPUTS. [Online]. Available: http://www.ti.com/lit/ds/symlink/cd54hc573.pdf .
LM340, LM340A and LM7805 Family Wide VIN 1.5-A Fixed Voltage Regulators. [Online]. Available: http://www.ti.com/lit/ds/symlink/lm340.pdf .
LM317 3-Terminal Adjustable Regulator. [Online]. Available: http://www.ti.com/lit/ds/slvs044x/slvs044x.pdf .
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