your lighting expert!

LED lights, Uncategorized

6 characteristics of LED lights

Home ┬╗ LED lights,Uncategorized ┬╗ 6 characteristics of LED lights

Energy saving features

1.LED light source has high luminous efficiency

Comparison of luminous efficiency: incandescent light efficiency is 10-15lm, tungsten halogen light efficiency is 12-24 lumens/watt, fluorescent light 50-90 lumens/watt, sodium light 90-140 lumen/watt, most of the power consumption becomes heat loss.

LED light efficiency: It can emit 50-200 lumens/watt, and its light emission has good monochromaticity and narrow spectrum. It can directly emit colored visible light without filtering.

2.LED light source consumes less power

The LED single tube power is 0.03-0.06 watts, using DC drive, and the single tube driving voltage is 1.5-3.5 volts. Current 15-18 mA has a fast response speed and can be operated at high frequency. When used with the same lighting effect, the power consumption is one ten thousandth of that of incandescent lamps and one half of that of fluorescent tubes. It is estimated in Japan that if it is used LEDs, which are twice as efficient as fluorescent lamps, can replace half of Japan’s incandescent and fluorescent lamps, saving the equivalent of 6 billion liters of crude oil every year. A fluorescent lamp with the same effect is more than 40 watts, while the power of each LED is only 18 watts. .

3.LED light source has long service life

Incandescent lamps, fluorescent lamps, and tungsten halogen lamps use electronic light field radiation to emit light. The filament emits light and is prone to burning, heat deposition, and light attenuation. LED lamps are small in size, light in weight, and encapsulated in epoxy resin, which can withstand high-strength mechanical impact and Vibration-resistant, not easily broken, with an average lifespan of 30,000-50,000 hours, the service life of LED lamps can reach 3-5 years, which can greatly reduce the maintenance costs of lamps and avoid the pain of frequent lamp replacement.

4.Strong safety and reliability

It has low calorific value, no thermal radiation, cold light source, safe to touch, can accurately control the light pattern and angle of light, and light color, no glare, and does not contain mercury, sodium and other substances that may be harmful to health.

5.LED light source is beneficial to environmental protection

LED is an all-solid-state light emitter, is impact-resistant and not easily broken, is recyclable, has no pollution, reduces the generation of harmful gases such as sulfur dioxide and nitrides, and greenhouse gases such as carbon dioxide, and improves people’s living environment. It can be called a “green lighting source.”

There are currently three technologies for producing white LEDs: one, which uses the principle of three primary colors and the three ultra-high brightness LEDs of red, green, and blue that can be produced to mix the light intensity in a ratio of 3:1:6 to produce white; the other, which uses ultra-high-brightness LEDs Highly InGan blue LED, with a small amount of yttrium-diamond-granite-based phosphor added to the tube, it can produce yellow-green light under blue light excitation, and this yellow-green light can be combined with the transmitted blue light to synthesize white light. The three types are incompatible with ultraviolet light. Light LED uses ultraviolet light to excite three primary color phosphors or other phosphors to produce white light mixed with multiple colors.

6.LED light source is more energy-saving

Of course, energy saving is the main reason why we consider using LEDs. LEDs may be more expensive than traditional light sources, but using energy savings in one year to recoup the investment in light sources will lead to a net payback period of several times the annual energy savings in 4 to 9 years.

life of lights

Constant current source driving is the best way to drive LEDs. Using constant current source driving, there is no need to connect a current limiting resistor in series with the output circuit. The current flowing through the LED is not affected by external power supply voltage changes, ambient temperature changes, and the discreteness of LED parameters. influence, so that the current can be kept constant and the various excellent characteristics of LED can be fully utilized.

An LED constant current power supply is used to power LED lamps. Since the current flowing through the LED is automatically detected and controlled during operation of the power supply, there is no need to worry about excessive current flowing through the LED at the moment of power on, or a load short circuit and burnout. Bad power supply.

lamp housing

LED lights have the characteristics of high efficiency, environmental protection and long life. However, people who often use LED lights will find that because LEDs are extremely bright, they can easily turn light energy into heat energy, making LED lights very hot. At this time, if the LED cannot dissipate heat as quickly as possible, its lifespan will be greatly reduced.

Many LED manufacturers use aluminum casings for LED lamps. Aluminum casings are easy to dissipate heat, have beautiful appearance and are lightweight. Many high-end electronic products use aluminum casings. For example, the company’s high-end notebook computer series “Mac Pro” uses an all-aluminum casing to facilitate notebook computer heat dissipation, so that the computer does not even need a fan.

The aluminum shell of LED can increase the life of the wick and make the LED light look beautiful. However, the aluminum lamp cup is relatively expensive and the production cost is very high. The lamp cup needs to be processed with a lathe. Therefore, some high-quality and medium-quality LED lights will use aluminum lamp housings.

Another common LED lamp housing is a plastic housing. Since the cost of plastic shells is very low, some low-end LED lamps will use plastic shells. However, plastic shells are not easy to dissipate heat, and plastics tend to melt and sublimate when heated to produce harmful gases. Therefore, Europe, North America, and Japan do not use plastic casings. Due to the large-scale demand for cheap LED lights in some areas of the country, plastic casings have a large sales volume in the country.

household lamp

Many LED lights can replace spiral incandescent lamps or energy-saving light bulbs, ranging from 5-40 watts, low-power incandescent lamps, to 60 watts (requiring only about 7 watts of electricity). As of 2010, some lamps can even replace higher-power light bulbs. For example, a 13-watt light bulb has about the same brightness as a 100-watt incandescent lamp. (General incandescent lamps have an efficiency standard of about 14 to 17 lumens/watt, depending on their size and voltage. According to EU standards, an “energy-saving light bulb” equivalent to a 60-watt incandescent lamp requires at least Can output 806 lumens.)

Most LED bulbs are designed to be non-dimmable, but some can be operated with dimmers and have a narrow illumination angle. Since 2010, the price of these light bulbs has dropped from $30 to $50. LED bulbs save more power than energy-saving bulbs and have a lifespan of up to 30,000 hours if heat is dissipated properly. Incandescent lamps generally only have a lifespan of 1,000 hours, and energy-saving light bulbs only have a lifespan of about 8,000 hours. Therefore, LED bulbs can be used for about 25 to 30 years, and the brightness decreases very little over time. The Energy Star standard stipulates that after a light bulb is used for 6,000 hours, the luminosity attenuation should be within 10%, and the worst case should not exceed 15%. Unlike fluorescent lamps, LED bulbs are mercury-free. LED bulbs also come in different color options. Although the selling price is higher, it is offset by lower electricity and maintenance costs.

Special Purpose

White LED bulbs are highly efficient and have a leading position in low-power consumption markets (such as flashlights, solar garden lights, pedestrian street lights, bicycle lights, etc.). Single-color LED lights are often used to make traffic lights and holiday lighting.

In 2010, LED lights became a hot topic in the horticulture and agricultural circles. NASA pioneered the use of LED lights for planting in space, and domestic and commercial indoor gardening followed suit. These special planting lights are specially designed so that the light waves are exactly the wavelengths absorbed by chlorophyll. This not only promotes growth, but also reduces light waves that are not absorbed by plants, causing waste. In the visible spectrum, only red and blue are needed for photosynthesis, so these lights are designed with both colors in mind. Compared with similar products, these LED lights can provide the same luminosity, do not require a ballast, and generate much less heat than gas discharge lamps, making them very suitable for indoor cultivation. Less heat can reduce evapotranspiration, thereby reducing the number of fillings. For this reason, when using these planting lights, plants should not be overwatered.

Buying guide

  1. Choose LED lights with the “Three Guarantees” commitment and choose lamps with the CCC certification mark;
  2. It depends on whether the LED lamp product labels are complete. Regular products should be labeled;
  3. Check whether the LED light power cord has the CCC safety certification mark;
  4. Check whether the live parts of the lamp are exposed. After the light source is installed in the lamp holder, fingers should not touch the live metal lamp holder;
  5. Check whether the LED chip is in accurate position and whether the lens or screen is worn.

Cause of damage

  1. The voltage of the current is unstable. An increase in the power supply voltage is particularly likely to cause damage to the LED lamp. There are many reasons for a sudden increase in voltage, such as quality problems with the power supply or improper use by the user. The power supply voltage may suddenly increase. high.
  2. The power supply path of the lamp is partially short-circuited. This is usually caused by a component in the circuit or a short-circuit in other wires that increases the voltage in this place.
  3. It may also be that the LED is damaged due to its own quality and forms a short circuit, and its original voltage drop is passed on to other LEDs.
  4. The heat dissipation effect of the lamp is not good. We all know that the lighting of the lamp is a heat dissipation process. If the temperature inside the lamp is too high, the characteristics of the LED will easily deteriorate. This can also easily cause damage to the LED lights.
  5. It is also possible that water has entered the lamp, because water is conductive, which will short-circuit the circuit of the lamp.
  6. Failure to do anti-static work during assembly has resulted in the interior of the LED being damaged by static electricity. Even if normal voltage and current values are applied, it is very easy to cause damage to the LED.

Common causes and solutions for LED light flickering

Normally, the human eye can detect light flickers with a frequency of up to 70 Hz, but not with frequencies higher than this. Therefore, in LED lighting applications, if the pulse signal has a low-frequency component with a frequency lower than 70 Hz, the human eye will feel flicker. Of course, in specific applications, there are many factors that may cause LED lights to flicker.

For example, in offline low-power LED lighting applications, a common power supply topology is an isolated flyback topology.

Taking the 8W offline LED driver GreenPoint┬« reference design that complies with the “Energy Star” solid-state lighting standard as an example, since the sinusoidal square wave power conversion of the flyback regulator does not provide constant energy to the primary bias, the dynamic self-power supply (DSS) ) circuit may activate and cause light to flicker.

To avoid this problem, the primary bias must be allowed to partially discharge during each half-cycle. Correspondingly, the values of the capacitors and resistors that make up the bias circuit need to be chosen appropriately.

Additionally, electromagnetic interference (EMI) filters are required even in applications using LED drivers that provide excellent power factor correction and support TRIAC dimming.

The transient current caused by the TRIAC step will excite the natural resonance of the inductor and capacitor in the EMI filter.

If this resonant characteristic causes the input current to drop below the TRIAC holding current, the TRIAC will shut down. After a short delay, the TRIAC usually turns on again, stimulating the same resonance.

This series of events may repeat multiple times during one half cycle of the input power waveform, resulting in visible LED flashes. To deal with this problem, a key requirement for TRIAC dimming is that the input capacitance of the EMI filter is extremely low and that this capacitance can be decoupled by the TRIAC and the winding impedance.

According to the formula, if the capacitance in the dimming module is reduced, the resistance of the resonant circuit can be increased, which in principle suppresses oscillation and restores the desired circuit operation.