To say that LED is used in flashlights, I am sorry to introduce the characteristics of LEDs first:
1, LED long life, generally can reach 50,000 hours or more than the traditional tungsten filament lamp life is 5 to 10 times higher.
2, cold light, low heat, will not damage the lamp holder security.
3, the reaction speed is fast, impact resistance, small size, easy to be small and lightweight.
4, energy saving, energy saving, new environmentally friendly light bulbs.
5, the reaction speed is as fast as 1us (microseconds), no need for warm lights can improve safety.
6, low-voltage drive safety.
Due to the above advantages, LED has been gradually applied to: backlight, traffic lights, urban lighting, automotive lights, general lighting. Here we will introduce the application of high-power LEDs on flashlights. In recent years, as the technology of high-brightness LEDs has matured and the cost has been declining, high-brightness LEDs of various specifications have been more commonly used in new types of lighting equipment. At present, this high-brightness LED is used in a flashlight, which is arguably the most suitable, because the high-brightness LED has high efficiency, long life and pure color. At present, high-power LEDs cannot be produced, but low-power LEDs are suitable for use in small lighting devices such as flashlights.
LED flashlight is a mature application lighting tool with LED light-emitting diode as the light source. It has the advantages of power saving, durability and brightness.
First, the type of LED flashlight
At present, various types of lighting flashlights on the market mainly include plastic flashlights, LED flashlights, iron flashlights, aluminum flashlights, stainless steel flashlights, hand-cranked flashlights, environmentally friendly flashlights, and electric mosquito swatter flashlights. Here we focus on the classification of LED flashlights.
At present, the common LED flashlights have a small keychain type, a multi-head type, a single lamp head and a high power type. From the type of power supply, there is an AA battery or an AAA battery, some use three AAA batteries, and some use three button batteries, as well as manual power generation.
Second, the performance characteristics of common types of LED flashlights
1. Compact LED flashlight
The compact LED flashlight refers to a multi-lamp small flashlight with an AA battery or AAA battery, or a pocket flashlight or keychain flashlight with three button batteries. These compact LED flashlights also have a poor concentrating effect and consume a lot of power. However, in the case of temporary emergency lighting or nighttime viewing in the city, it is not practical for a long time. Because the flashlight is not used for a long time, it is often stored for temporary use. Therefore, it is best to use a well-sealed alkaline battery (usually it can be stored for two or three years without failure). Do not use ordinary carbon batteries, so as not to use it for a long time. The electrolyte is drained and the flashlight is damaged.
2. Manual charging LED flashlight
There are two types of manual charging LED flashlights. One type of such flashlight has a movable cylindrical magnet that slides in a coil when the hand is shaken. The coil generates a current and is rectified to charge the battery to illuminate an LED. The other is the flashlight that drives the generator to rotate by hand. The price of this flashlight is lower, but most of these manually generated LED flashlights are not reliable.
3. Multi-lamp type with three batteries
The number of lamp caps (ie, LEDs) ranges from a dozen to twenty or thirty, and more than forty lamps are reached. The outer casing of the flashlight is mostly made of aluminum alloy. Some of the switches of the flashlight are arranged at the tail, and some are arranged at the front part of the side. The side front switch is more convenient to use. Since the ignition voltage of the high-brightness LED is about 3V, the LED flashlight with three AAA batteries can be directly lit without boosting, so the power efficiency is high, and only a small energy consumption is limited. On the flow resistor. It should be noted that the more LEDs, the better. Also note that it is necessary to look at whether there is a good quality reflective film behind the lamp head, which can reflect the light scattered by the LED, which can increase the brightness of the flashlight by 20% to 30%. The main disadvantage of this multi-lamp flashlight is the poly The light effect is not very good, obviously not as good as the ordinary flashlight, so it is not bright enough when it is irradiated to a distant object.
4. Single lamp head high power LED flashlight
The single-lamp high-power LED flashlight refers to a single LED light-emitting flashlight with a power of 1W to 5W. The high-power LEDs used in this single-lamp flashlight are either domestic or imported. In general, imported high-power LEDs have higher luminous efficacy, but the price is much higher. The biggest advantage of this single-lamp high-power LED flashlight is that the concentrating effect is better, but it is still necessary to see whether the concentrator of the flashlight is made well. The production of a more regular single-lamp high-power LED flashlight, the concentrating effect is close to the ordinary flashlight, and the brightness is higher.
5. Plastic shell rechargeable LED flashlight
Rechargeable flashlights in plastic housings are often cheaper multi-head LED flashlights with lead-acid batteries. The flashlight has a lamp holder ranging from five to more than twenty, and also has a capacitor with a step-down capacitor, and the charging is also convenient. This type of plastic case rechargeable LED flashlight, the price is generally not high. The concentrating effect of this type of flashlight is not very good, but the overall brightness is good. The main disadvantage is that the lead-acid battery used needs to be charged frequently to prevent the battery from failing in advance; even if the maintenance is good, this type of lead-acid battery can only be used for one year. More will fail. The flashlight is a structure in which a lead-acid battery and a flashlight are integrated, and it is generally not easy to replace after failure.
Third, the considerations for the purchase of LED flashlight
1. The number of heads is moderate. Generally, the number of households should not exceed 12, and the batteries used are better in 2~3, which is a little wasteful. For other special needs, you can determine it according to your needs.
2, welding must be strong. Each diode is connected to the board by soldering. If there is a bad solder joint, it may cause no light or affect the overall use.
3. Focus on the spot of the electric beads as much as possible. This kind of flashlight can not adjust the focal length like ordinary flashlight. When buying, be careful not to have astigmatism.
4, the power switch contact should be obvious. This type of flashlight uses a rotary switch. It is tightened and then turned off. If the contact is not obvious, it is easy to cause the phenomenon of light up and off.
5, pay attention to waterproof. Because it belongs to electronic products, there is a circuit board at the front of the flashlight. Once it enters the water, it is easy to short-circuit and cause damage.
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