Light point control.The light bulbs of traditional cars are all halogen bulbs. Halogen bulbs are the improved products of incandescent lamps. They have not changed much in the hundreds of years since their invention. The technology is mature and the price is low. Because it is cheap enough, the natural color temperature is low, the penetration is great in rainy and snowy days, and the 12V low-voltage direct drive... A series of advantages have made it firmly occupy the top position in the car lamp market for decades.
In fact, halogen bulbs have always been used as "standard bulbs": any evaluation of car lighting parameters needs to be based on halogen bulbs during development. Therefore, the luminous design of any LED lamp must also "approach halogen bulbs", and the most critical thing is the control of the luminous point.
The luminous point of halogen lamps is smaller than "half a grain of rice"!
The luminous point as thin as a needle tip is its magic weapon for focusing light
We pick up a halogen bulb and observe it carefully. We can see that the filament of the Lu Su bulb (the metal wire spirally wound in the center of the bulb) is actually very short. The volume of that "spiral wire" is only about as small as "half a grain of rice". If we wear "welding goggles" to observe a lit halogen bulb, we will find that the part of the halogen bulb that really emits light is that "spiral wire". It is precisely because of this that halogen bulbs are typical "point light sources".
The light point is very small (less than half a grain of rice), which is approximately equivalent to a point the size of a needle tip. Therefore, the "focus" of the light is very concentrated. Even without a lens, any reflector can successfully complete the task of focusing and controlling light (common sense: the smaller the light point, the better the focusing). Therefore, halogen bulbs are the "least picky" bulbs, and they can perform well with or without lenses.
The light point of a xenon lamp is only as big as a soybean
So a lens is needed to diffuse light
So how does a xenon lamp perform in this regard? (In fact, many readers have been leaving messages asking about xenon lamps). Here I can tell you clearly: xenon lamps are also very easy to "diverge light", and their performance in focusing light is far inferior to traditional halogen lamps. Don't believe it? Let's take a look at the working principle of the xenon lamp:
In the core component of the xenon lamp, the reaction tube (a quartz glass tube), high-pressure xenon gas is encapsulated, and two electrodes are installed at both ends of the reaction tube. When we turn on the xenon lamp, the high-voltage electricity of about 27,000 volts on the electrode instantly "breaks through the xenon gas", and the high-temperature arc instantly ionizes the xenon gas, and then the xenon gas emits light by itself. At this time, only low-voltage electricity is needed to keep the bulb working.
So from the principle, we can directly understand that the core part of the xenon lamp is the "glass tube encapsulating xenon gas". How big is this thing? - About the size of a soybean. It is many times larger than the "half grain of rice" of a halogen lamp. Because the volume of the luminous core is obviously larger, the focusing effect of the xenon lamp is still far inferior to that of the halogen lamp. Therefore, don't believe that "xenon lamps can be used without lenses"! The truth is that "xenon lamps are useless without lenses"!