Nowadays, display panels use white LEDs backlight to provide thin and lightweight devices with high brightness. The spectrum of white LEDs has an important blue component with a peak wavelength around 450 to 470 nm. The term “blue light hazard” (BLH) refers to the photochemical damage of the retina in the range of 380–550 nm. Blue light retinal injury can result from viewing either an extremely bright light for a short duration or a less bright light for a longer duration. Our studies and measurements focused on usual display panels of desktop and laptop PCs, used many hours a day by the operators who are endangered by the cumulative effect of blue light exposure. The paper will present the results and recommendations in order to order to minimize the risk of blue light exposure.
The problem of noise introduced by optocouplers has been well documented and should be a concern for electronic designers. The paper investigates the effect of phase jitter introduced by optocouplers into systems that are sensitive to this type of noise, mainly paying attention to RFID systems.
The paper presents the experimental results obtained by using the embedded protection diode for monitoring the operating temperature of the power LEDs. The experiments have been done in both heating and cooling conditions, in order to prove the accuracy of the proposed method. Monitoring the thermal regime of power LEDs by using the embedded protection diode proved to be a viable solution.
The characterization of the quality of communication between an RFID reader and a transponder at all expected positions of the latter on the reader antenna is of primal importance for the evaluation of performance of an RFID system. Continuing the line of instruments developed for this purpose by the authors, the present work proposes an enhanced version of a previously introduced automated platform for 2D evaluation. By featuring higher performance in terms of mechanical speed, the new version allows to obtain 2D maps of communication with a higher resolution that would have been prohibitive in terms of test duration with the previous version. The list of measurement procedures that can be executed with the platform is now enlarged with additional ones, such as the determination of the variation of the magnetic coupling between transponder and antenna across the antenna surface and the utilization of transponder simulators for evaluation of the quality of communication.
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