[Deceleration glass] What is deceleration glass What is the principle of deceleration glass
Reduction glass is actually a kind of laminated glass, which is composed of two layers of tempered glass sandwiched with a layer of PVB film When this kind of glass is damaged by external force, the glass fragments will still stick to the film and will not fly out and cause secondary damage to the vehicle occupants. High-quality deceleration glass has good optical properties, good light transmittance, and no light distortion. It can very realistically reflect the shape and operating status of the scenery outside. The vision is very clear, the same as the visual effect without glass, plus interlayer technology. It also has certain heat insulation and soft light effects, making people feel more comfortable. In fact, the correct name for glass used in transportation vehicles (including cars, trains, airplanes, etc.) is: safety glass.
Origin
The term “speed reduction glass” is an outstanding “invention” of the older generation of drivers in our country, 50-60In the 1990s, some veteran drivers who used to drive large trucks and later drove cars found that driving a large truck had a significantly different sense of speed than driving a small car, but they could not use their knowledge to explain this phenomenon. , so they thought that foreigners (cars at that time were all foreign products) used some high-tech glass on cars to slow down the car, thus creating the term “deceleration glass”. Later, it became widely circulated as a rumor and was used by some businesses to deceive consumers. It was also used by some car owners to show off the quality of their cars. Many people were deeply confused because they did not understand its principle. In fact, the Western countries that produced cars at that time did not have this term. The Chinese used it too much. Some news media that did not know the reason were also promoting it, and the translation had to follow suit, so “decelerating glass” came into being. ” is an English vocabulary, and abroad it is also classified as a “Chinese characteristic” vocabulary together with “white strips” and so on. Although it is an “invention” of the Chinese, it is an “invention” that goes against scientific common sense. In fact, it is found in the formal technical materials of domestic and foreign design and production units such as automobiles and automobile glass, or in the textbooks of relevant colleges and universities. The word cannot be found.
Non-existence
The proof is simple.
First, let the distance traveled by the train be S, and let it take time for the train to complete the distance S fort. Suppose there is a passenger in the train who is stationary relative to the train. He looks out from when the train starts to move, and his gaze is always perpendicular to the side of the train car until the train stops.
① When there is no glass, the speed of the passenger’s gaze movement is obviously the same as the speed of the train, which is = .
② When there is a ‘speed reduction glass’, since the passenger takes the train from the starting point to the ending point, the distance he passes is S, and his eyes scan The distance traveled is also S; since he and the train are relatively stationary, the time he looks at the outside of the train is neither faster nor slower than the time the train moves. . Therefore, the time the passenger looks at the outside of the train is exactly t. Therefore, the speed of the passenger’s gaze movement is.
According to the principle of relative motion, the speed at which the passenger sees the scenery outside the window should be equal to the speed of his gaze movement. And because , the speed at which the passenger sees the movement outside the window is exactly the same in the two situations ,“Deceleration glass” does not play the role of deceleration. The so-called “deceleration” is just that people’s visual experience is different.
Overview Since there is no deceleration glass, why do we open different ones? Will the car have different sense of speed? It can be explained from the following aspects.
Visual error
The variable that people use to judge motion perception is not linear speed, but angular speed (viewing angle/ seconds). A point-like object moves at the same speed, if its direction of movement is exactly parallel to the line of sight of the eye, this The angle of view when is 0° (Of course, people have two eyes, it is impossible for both eyes to be 0, in fact it can only be close to 0), that is, the angular velocity is 0, and you can hardly feel it It is moving; when the direction of movement is perpendicular to the line of sight of the eye, the angular velocity is the largest, and you can feel the fast movement speed; in addition, the size of the angular velocity is also related to the distance. The farther the distance, the smaller the angular velocity is, and the closer the distance. , the greater the angular velocity. It can be seen that when viewing an object with the same moving speed at different positions (different angles, different distances), you will have a completely different sense of speed! This is a visual error. Open differentThe car will have a different field of view and a different sense of speed. For example, cars and buses have flat heads, the front glass is almost vertical, and the seats are high. The driver can see the road very close to the front of the car, and naturally feels faster (if the driver is on the floor of the car) Make a hole and let you look down vertically, you will be even more surprised). The car is different. The car not only has a longer front. In order to look beautiful and reduce wind resistance, the front glass is installed at an angle, and the slope is larger. The seats are farther back, so that the distance between people and the front of the car is reduced. At the same time, the seat of the car is very low, so you can only see the road in front of the car from a relatively flat angle. The road you can see is quite different from where you sit. Horizontal distance (that is, there is a long road ahead of the car that is blocked by the front of the car and cannot be seen), you feel much slower! This is the main reason for “slowing down”. Moreover, the more high-end the car, the longer the front part of the car, the greater the inclination of the front windshield, and the farther the driver is from the front of the car, the more obvious this “deceleration” effect will be. Isn’t the moon moving around the earth very slowly (average revolution speed 1.023 kilometers / seconds!)? But why can’t we almost feel it? What makes it “slow down”? It is because the distance is too far (the viewing angle is too small) that our eyes cannot distinguish, resulting in the illusion of “slowness”!
The stability of the car
The same car is driven on a rural road with poor road surface quality It will feel very fast at a speed of 40km. Because at this time, in addition to the forward motion of the vehicle, there is also a lot of irregular shaking caused by the bumps of the vehicle, which makes it difficult for the human eye to capture the scenery outside, giving you the feeling of “fast”; On the highway, the irregular shaking has basically disappeared, and it feels very slow even when driving 100km per hour. It can be seen that the smoother the vehicle travels, the slower it feels. There is no doubt that high-end cars have better shock absorption, ride more smoothly, and feel less fast.
Quality of glass
As mentioned before, good glass should have the same feeling as no glass, so that the scenery outside will not look good. It will deform and feel comfortable. If the quality of the glass is not good, the scenery outside will be deformed when viewed through the glass, superimposing a kind of blur caused by the deformation on the moving objects, which will easily make the driver visually fatigued and give you a sense of pleasure.
Distance
Looking at objects with the same speed at different distances will have different feelings.Close objects outside the car window will flash by, but when looking at distant mountain peaks, they will feel moving very slowly. The same goes for driving. Different car drivers have different visions. For example, compare driving a car with driving a bus.
This is the whole secret of “slow glass”.
Introduction
Reduction glass is actually what is usually called a laminated car front windshield. Some tempered front windshields have poor optical performance and poor transition. Smooth, if the driver drives for a long time, it will cause the eyes to tire easily and feel dizzy. The optical properties of laminated glass are good, there is no light distortion, and the vision from the car is very clear. In addition, the introduction of new technologies in laminated glass makes the light very soft, which can give people a feeling of slowing down.
Laminated glass is a kind of safety glass made of two layers of glass with a layer of PVB film in between. Now some automotive glass manufacturers use the most advanced glass and film The manufactured front windshield has a better heat-absorbing effect, thereby increasing the cooling feeling inside the car in hot summer. “Deceleration glass” does not exist, just because the name is unscientific, or it can be considered misleading for commercial purposes.
Principle
The main function of glass is to transmit light, and the best effect it can have is: let this The glass’s presence is exactly the same as its absence. In fact, deceleration glass does not make the movement of external scenery appear slower than it actually is, but it looks consistent with the actual speed – exactly the same as without glass. Therefore, the correct name of the so-called deceleration glass should be “no speed increase” Glass”. Other ordinary glass, relatively speaking, can be called “speed-increasing glass”.
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