Taking the single chip AT89C51 as the control core, the semiconductor refrigeration technology is introduced into the LED heat dissipation research. The PID algorithm and PWM modulation technology are used to control the input voltage of the semiconductor refrigeration chip, and then the control of the semiconductor refrigeration power is realized. The feasibility of this method.
With the rapid development of LED technology, LED has entered the market of general lighting. However, the development of LED lighting systems is largely affected by thermal issues. For high-power LEDs, heat dissipation has become a bottleneck restricting its development. The semiconductor refrigeration technology has the advantages of small size, no need to add refrigerant, simple structure, no noise, stability and reliability. With the advancement of semiconductor material technology and the discovery of high thermoelectric conversion materials, semiconductor refrigeration technology is used to solve the LED lighting system. The heat dissipation problem will have a very realistic meaning.
1. The cause of LED heat generation and the effect of heat on LED performance
At the forward voltage, the electrons receive energy from the power source. Under the driving of the electric field, the electric field of the PN junction is overcome, and the N region transitions to the P region. These electrons recombine with the holes in the P region. Since the free electrons drifting to the P region have higher energy than the P region valence electrons, the electrons return to the low energy state during recombination, and the excess energy is released in the form of photons. However, only 30% to 40% of the released photons are converted into light energy, and the remaining 60% to 70% are converted into thermal energy in the form of point vibration.
Since the LED is a semiconductor light-emitting device, and the semiconductor device changes itself with changes in temperature, the inherent characteristics thereof change significantly. An increase in the junction temperature of the LED results in a change in device performance and attenuation. This change is mainly reflected in the following three aspects:
1. Reduce the external quantum efficiency of the LED;
2. Shorten the life of the LED;
3. The main wavelength causing the LED to emit light is shifted, resulting in a shift in the color of the light source. High-power LEDs generally use more than 1W of electric power input, which generates a lot of heat, and solving the heat dissipation problem is a top priority.
2, semiconductor refrigeration principle
Semiconductor refrigeration, also known as electronic refrigeration, or thermoelectric cooling, is a discipline that has developed from the 1950s on the edge of refrigeration technology and semiconductor technology. It is also known as the world's three major refrigeration systems with compression refrigeration and absorption refrigeration. The basic device of a semiconductor refrigerator is a thermocouple pair, that is, an N-type semiconductor and a P-type semiconductor are connected into a thermocouple (see Figure 1). After the DC current is applied, temperature difference and heat transfer occur at the interface. . A pair of pairs of semiconductor thermocouples are connected in series on the circuit, and the heat transfer is parallel, thus forming a common refrigeration thermopile. By means of various heat transfer means such as heat exchangers, the hot end of the thermopile continuously dissipates heat and maintains a certain temperature, and the cold end of the thermopile is placed in the working environment to absorb heat and cool down, which is the principle of semiconductor refrigeration.
Figure 1 Semiconductor refrigeration chip TEC structure
This article uses semiconductor refrigeration because it has no mechanical rotating parts, no refrigerant, no pollution, high reliability, long life and easy control. Compared with other refrigeration systems, the volume and power can be made very small, which is very suitable for LED limited. Application in the workspace.
Icicle & Curtain Lights
The curtain light is mainly composed of a light string and a fixing hook; the light string is formed by connecting light bulb and wire; the fixing hook is a fitting having a wire groove and a hook, and the hook is formed above the wire groove. According to a certain shape, the wires on the light string can be fixed in the wire trough, so that various styles of curtain lights can be assembled., and the whole curtain light can be hung on the frame of the window and door through the hook when in use, and with the light bulb on the light chain to achieve the effect of dressing up windows and doors.
Usage one of Curtain lights: decorative bedroom
In fact, curtain lights are generally made up of a combination of small light strings of different colors, so you can transform a lot of shapes, decorate in all aspects, you can choose a part of the curtain light string, hanging on both sides of bedroom curtains and bedroom door, the ceiling can also be combined with some romantic patterns, and if the light selection is softer, it must very beautiful when the advent of the night lights come on.
Usage two of Curtain lights: decorative bed
The curtain and the bed curtain have similar effect , it can be operated if your bed with a bedpost or a bed curtain, if all the light string of the curtain light are hung on the bed or mattress, or directly take the light as a curtain and it looks like a waterfall when turn it on at night .
Usage three of Curtain lights: decorative wall surface
Curtain lights can be used to decorate walls, it is not only simply hanging on the wall as decoration, but also can be decorated with some murals or room structure, even it can be combined into a pattern or letter and so on. It is convenient to operate and very innovative.
Usage four of Curtain lights: decorative windows
The curtain lights is playing a major role to decorate windows, but the new method certainly not an ordinary decoration, it not only can be decorated on the window frame, but also can use as curtain, and it can sew special pattern on the curtains, then a beautiful pattern will be appeared when you draw the curtain at night.
Usage five of Curtain lights: decorative items
There are several kinds of items in the family unused and not pretty, and the key is that they are indispensable items. Such items are often incongruous in space and obtrusive, so you can use the curtain lights to decorate them, to wrap around them to create different scenery, like some toys can also be decorated.
Usage six of Curtain lights: decorative balcony
The monotonous balcony can also be very romantic. Choose star-shaped curtain light to decorate on the side of the balcony or on the balcony of the plant. Such a balcony is very special.
Icicle & Curtain Lights,LED Rubber Icicle Light,LED Mesh Lights,LED Net Curtain Light
Heshan Jianhao Lighting Industrial Co., Ltd. , http://www.sunclubtw.com