Design of PDLC film-based light filtering control system

It is known that exposure to natural and artificial light sources has positive and negative effects on living and non-living entities. On the other hand, there are situations where light needs to be limited for purposes such as air conditioning, insulation, and treatment. Therefore, the transmission, insulation, and filtering processes are crucial for the controlled use of light according to need. Polymer Dispersed Liquid Crystal (PDLC) films are widely used in light insulation and shading applications due to their various advantages such as fast switching and easily adjustable transparency. In this thesis study, a control system for PDLC film-based light filtering is designed and its performance is examined. The hardware of the developed system consists of control unit, measurement unit, power unit, user interface and PDLC film assembly. In the control unit where the microcontroller card is used, the data collection and control operations required for the system are carried out depending on the visible (VIS), infrared (IR) and ultraviolet (UV) light filtering settings. In the power unit, the supply required for the PDLC film is provided by the designed microcontroller-based adjustable DC-AC inverter. The necessary feedback for control is obtained by measuring VIS, IR and UV light levels with the measurement unit. OLED display and buttons are used as the user interface. In the study, a setup is created using PDLC film with dimensions of 15 cm x 20 cm. The embedded system software for the operation of the developed system is coded in Arduino C language. Within the scope of experimental studies to examine the performance of the designed system, the light filtering effect is examined by applying PDLC film in various energy forms with the control system. Consequently, by automatically controlling the power of the PDLC film system and adjusting its transparency, the visible light transmission (VLT) ratio could be set between 5.1% and 73.5%, the infrared light transmission (IRT) ratio between 9.6% and 82.4%, and the ultraviolet light transmission (UVT) ratio between 0% and 0.2% for applied AC voltage values ranging from 0 to 30 Vrms. Thus, it has been observed that filtering can be performed to a certain extent depending on the light transmission adjusted by the PDLC film.