To talk about the application of LED in flashlight, I'm sorry to first introduce the characteristics of LED:

1. The ultra long service life of LED can generally reach more than 50000 hours, which is 5 ~ 10 times longer than that of traditional tungsten filament lamp.

2. Cold light, low heat, no damage to the lamp holder, high safety.

3. Fast reaction speed, impact resistance, small volume, easy to be small and lightweight, etc.

4. Power saving, energy saving, new environmental protection bulb.

5. The reaction speed is fast, as long as 1US (microsecond), and the safety can be improved without warming the lamp.

6. Low voltage drive safety.

Due to the above advantages, LED has been gradually applied to backlight, traffic lights, urban lighting, car lights and general lighting. Here I want to introduce the application of high-power LED in flashlight. In recent years, with the gradual maturity of high brightness LED technology and the continuous decline of cost, various high brightness LEDs of different specifications are widely used in new lighting equipment. At present, this kind of high brightness LED is suitable for flashlight, because it has high efficiency, long service life and pure color. At present, high-power LED can not be made, but low-power LED is very suitable for small lighting devices such as flashlight.

LED flashlight is a mature application lighting tool with LED as light source. It has the advantages of power saving, durability, strong brightness and so on.

1、 Type of LED flashlight

At present, there are many kinds of lighting flashlights in the market, mainly including plastic flashlights, LED flashlights, iron flashlights, aluminum alloy flashlights, stainless steel flashlights, hand-held flashlights, environmental protection flashlights, mosquito clapping flashlights and so on. Here we focus on the classification of LED flashlights.

At present, the common LED flashlight has small key chain type, multi lamp head type, single lamp head high-power type and so on. From the type of power supply, some use one AA battery or one AAA battery, some use three AAA batteries, some use three button batteries, and some use manual power generation.

2、 Performance characteristics of common types of LED flashlights

1. Compact LED flashlight

Compact LED flashlight refers to a small multi lamp flashlight with one AA battery or AAA battery, or a pocket flashlight or key ring flashlight with three button batteries. This kind of compact LED flashlight has poor focusing effect and high power consumption, but it still has certain practical value when it is not used for a long time in cities, such as temporary emergency lighting or night viewing. This kind of flashlight is often stored for temporary use due to its short service time. Therefore, the alkaline battery with good sealing (generally can be stored for two or three years without failure) is adopted. Do not use ordinary carbon battery, so as not to flow out electrolyte for a long time and damage the flashlight.

2. Manual charging LED flashlight

There are two types of manually charged LED flashlights. One is that there is a movable cylindrical magnet in the flashlight, which can slide in a coil when shaking by hand. The coil generates current and charges the battery after rectification to light up an LED. The other is the flashlight that drives the generator to rotate by hand. The price of this kind of flashlight is lower, but most of these LED flashlights with manual power generation are unreliable.

3. Multi head type with three batteries

The number of lamp caps (i.e. LED) ranges from more than ten to twenty or thirty, and more than forty lamp caps. The shell of the flashlight is mostly made of aluminum alloy. Some switches of the flashlight are set at the tail and some at the side front. The side front switch is more convenient to use. Since the ignition voltage of high brightness LED is about 3V, the LED flashlight with three AAA batteries can be lit directly without boosting. Therefore, the efficiency of power supply is high, and only a small amount of energy is consumed on the current limiting resistance. It should be noted that the more LEDs, the better. It should also be noted that it is necessary to see whether there is a high-quality reflective film behind the lamp cap, which can reflect the light scattered by the LED and improve the brightness of the flashlight by 20% ~ 30%. The main disadvantage of this multi lamp cap flashlight is that the focusing effect is not very good, which is obviously not as good as that of the ordinary flashlight, so it is not bright enough when shining on a long-distance object.

4. High power LED flashlight with single lamp cap

Single lamp cap high-power LED flashlight refers to a flashlight that uses a single LED with a power of 1W ~ 5W. The high-power LED used in this single cap flashlight is either domestic or imported. Generally speaking, imported high-power LED has higher luminous effect, but the price is much higher. The great advantage of this single lamp cap high-power LED flashlight is that it has a good focusing effect, but it still depends on whether the spotlight of the flashlight is well made. Manufacturing a more formal single lamp cap high-power LED flashlight, its focusing effect is close to that of ordinary flashlight, and the brightness is higher.

5. Plastic case rechargeable LED flashlight

Rechargeable flashlights with plastic shells are often cheaper LED flashlights with lead-acid batteries. The lamp caps of this flashlight range from five to more than 20, and it is also equipped with a capacitor step-down charger, which is also convenient for charging. This kind of plastic shell rechargeable LED flashlight, the price is generally not high. The concentrating effect of this kind of flashlight is not very good, but the overall brightness is good. Its main disadvantage is that the lead-acid battery needs to be charged frequently to prevent the battery from failure in advance; Even if the maintenance is good, this kind of lead-acid battery can only be used for more than a year and will fail. This kind of flashlight is an integrated structure made of lead-acid battery and flashlight, which is generally not easy to replace after failure.

3、 Precautions for purchasing LED flashlight

1. The number of heads is moderate. Generally, the number of household batteries should not exceed 12. It is better to use 2 ~ 3 batteries. It is a little wasteful if it is larger. Those used for other special needs can be determined according to their own needs.

2. Weld firmly. Each diode is connected to the circuit board by welding. If there is faulty welding and poor contact, it may not light up or affect the overall use.

3. Try to concentrate the light collecting surface of the electric bead. Unlike ordinary flashlights, this kind of flashlight can adjust the focal length. When purchasing, you should pay attention not to have astigmatism.

4. The contact of power switch shall be obvious. This kind of flashlight mostly adopts rotary switch, which turns on when tightened and turns off when loosened. If the contact is not obvious, it is easy to cause the phenomenon of on and off.

5. Pay attention to waterproof. As it is an electronic product, there is a circuit board in front of the flashlight, which is prone to short circuit and damage in case of water inflow.