I. Summary Mechanical percussion keyboards are becoming more common in daily life, and the introduction of a new non-contact keyboard has the potential to significantly enhance people's quality of life. This project aims to explore the development of such a keyboard, which could offer practical benefits and technological innovation. The design utilizes the high-performance MIPS core MCU-PIC32MX460F512L development board, specifically the Cerebot 32MX4 Board from Microchip, as the main control unit. LEDs are chosen as one of the key components due to their cost-effectiveness, wide application, and aesthetic appeal. As an inductive device, LEDs can serve as a light source with excellent brightness and efficiency, making them ideal for use in a contactless keyboard system. Selection of Two Sensors 2.1 About the Selection of Several Sensors 1. Photodiode Photodiodes are low-cost and highly accurate under normal lighting conditions. However, they do not function effectively at night, as they require ambient light to operate properly. Therefore, they are not suitable for use as sensors in a keyboard that needs to work in low-light environments. 3. Proximity Sensor Proximity sensors have strong recognition capabilities and can detect objects from a distance. However, they tend to be more expensive compared to other sensor types, which increases the overall cost of the system. 4. Infrared Transceiver Integrated Sensor These sensors are convenient for both transmitting and receiving signals. However, they are relatively costly when used with LEDs, and their power consumption is slightly higher than that of standard LEDs. 5. Light-Emitting Diodes (LEDs) LEDs are capable of sensing light within a certain range and can be effectively used in a keyboard system. They also provide illumination, even in dark environments, making them a versatile choice. 2.2 About the Selection of Light-Emitting Diodes To achieve the desired performance, LEDs were selected as the primary sensing component. Red LEDs are particularly sensitive, although their detection range is limited. Based on light energy characteristics and reflection properties, infrared light is most efficient for transmission, followed by red visible light. Therefore, red LEDs are preferred for this application. When selecting LED tubes, brightness is a critical factor. Higher brightness improves both recognition accuracy and illumination. Additionally, the emission should be uniform and concentrated rather than too divergent. This ensures better signal consistency and reliability. A "white-red" LED was found to be suitable for use as a sensor in this project. For "red-red" Preliminary testing showed that "red-red" LEDs are not suitable for this purpose. 3. Characteristics of LEDs LEDs are known for their low power consumption and high luminous efficiency, saving up to 70-80% of electricity compared to fluorescent lamps. They have a long lifespan—typically over 5,000 hours, with some models lasting up to 100,000 hours. Their performance remains stable, with only a 30% light decay after 50,000 hours. They are environmentally friendly, containing no harmful substances like mercury and being recyclable. They emit no infrared or ultraviolet radiation, which helps reduce mosquito attraction. LEDs also provide better eye comfort due to constant current driving, eliminating flicker issues. Their compact size allows flexible design and integration into various modules. The manufacturing process of LEDs allows for different divergence angles. For example: (The type of divergence angle of the LED. A smaller divergence angle is preferable for improving detection accuracy.) Mull-Gang Integrated Switches Spec,Mull-Gang Integrated Switches Low Profile,Mull-Gang Integrated Switches Gray,Mull-Gang Integrated Switches Yellow Yang Guang Auli Electronic Appliances Co., Ltd. , https://www.ygpowerstrips.com
