With the continuous development of LED technology , LED is made possible as an illumination source. Since the light source has strict requirements on the color rendering index CRI in the lighting fixture, the current white LED technology is not mature in color rendering, making it become Restricting LED as a major obstacle to lighting sources.
White light is a composite light, and it is easy to decompose the light of various colors contained in white light by a prism. LED is a kind of light source with comprehensive chromatogram. This wide color gamut has laid a theoretical foundation for the high color rendering of LED lighting products.
Light is a substance with wave-particle two-phase properties. This material contains the characteristics of the wave and contains the characteristics of the particle, which makes it have strong composite characteristics. Therefore, in terms of the nature of light and the characteristics of LED, LEDs are becoming a high-quality illumination source.
At present, white LED technology mainly adopts the manufacturing process of blue-chip chip coating phosphor. This technology is developed by Nichia Corporation and follows the principle of fluorescent light in a certain sense. This technology is lacking in red and green light components. In order to make up for this defect, phosphor technology has become the main direction of the industry.
The blue chip is coated with phosphor to make white light technology. This technology can produce white light with better effect in principle, but the difference in the adaptability to the environment during use makes the difference between theory and actual product. The difference is largely due to the effect of the LED heat build-up on the phosphor.
We all have the experience that high-power white LEDs gradually reach equilibrium with the generation of heat and heat loss as the working time progresses. The higher the temperature of this equilibrium state, the more the influence on the white LEDs using the same type of phosphors. Large, the following figure shows the effect of temperature on the luminescent properties of the phosphor;
As can be seen from the above figure, as the LED temperature continues to rise, the phosphor activity will be greatly reduced (Fahrenheit / Celsius conversion formula: Celsius = 5 / 9 * (Fahrenheit - 32), at 100 degrees Fahrenheit phosphor The activity is preferred, but the activity of the phosphor is substantially lost at around 250 degrees Fahrenheit (i.e., 120 degrees Celsius).
While affecting the activity of the phosphor, the temperature also has a certain influence on the wavelength of the light wave excited by the phosphor. The following figure shows the effect of temperature on the wavelength of the phosphor.
TO-220 Transistor Outline Package is a type of in-line package often used in high-power transistors and small and medium-sized integrated circuits.
It not only plays the role of mounting, fixing, sealing, protecting the chip and enhancing the electrothermal performance, but also connects to the pins of the package shell with wires through the contacts on the chip, and these pins pass through the wires on the printed circuit board. Connect with other devices to realize the connection between the internal chip and the external circuit.Because the chip must be isolated from the outside world to prevent impurities in the air from corroding the chip circuit and causing electrical performance degradation. On the other hand, the packaged chip is also easier to install and transport.
TO-220 package is a kind of in-line package that is often used for fast recovery diodes. TO-220AC represents a single tube with only two pins and only one chip inside.
The diodes are packaged in TO-220AC and can be used in switch mode power supplies (SMPS), power factor correction (PFC), engine drives, photovoltaic inverters, uninterruptible power supplies, wind engines, train traction systems, electric vehicles and other fields.
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