The biological effects of a light-emitting diode (LED) light therapy device are determined by irradiation parameters, mainly wavelength and power density. However, using a battery to provide power causes a problem in the variation of LED power density during battery discharge. As a result, maintaining a stable LED power density, along with extending battery life and operating time, are the primary concerns in designing a LED light therapy device. The present study aims to introduce a LED light therapy device design with different LED color power density control. A Fuzzy logic, based on the relationship between LED power density and operating time, was proposed to control constant power density in this design. The experimental results demonstrate that by using the designed controller, the LED light therapy device's power density (40 mW/cm², 50 mW/cm², 60 mW/cm² for red, blue, and green light, respectively) can be controlled. The newly designed LED light therapy device could be considered an advanced version with energy savings and stabilized LED power emitting property under a broad range voltage variation.

发光二极管 (LED) 光疗设备的生物效应取决于照射参数，主要是波长和功率密度。然而，使用电池供电会导致电池放电过程中LED功率密度变化的问题。因此，保持稳定的 LED 功率密度以及延长电池寿命和工作时间是设计 LED 光疗设备的主要考虑因素。本研究旨在介绍具有不同 LED 颜色功率密度控制的 LED 光疗设备设计。在该设计中，基于 LED 功率密度和工作时间之间的关系，提出了一种模糊逻辑来控制恒定功率密度。实验结果表明，通过使用设计的控制器，LED 光疗设备的功率密度（40 mW/cm²，50毫瓦/厘米²，60毫瓦/厘米²为红，蓝，和绿色光，分别地）可以被控制。新设计的 LED 光疗仪可被视为具有节能和稳定 LED 功率在宽范围电压变化下的先进版本。