Every self-service purchase is a science fiction blockbuster

  Some people think that the vending machine is unfathomable, with one hand to pay and one hand to deliver, with a quiet look. The reason for this is because everyone is very curious, how does the vending machine know whether the coin put in is true or false, and what is the size of the denomination?
  Recently, there is a very hot video on the Internet that specifically demonstrates the process of self-service shopping with coins. I saw the coins go through five levels and cut six, just like the game upgrade and Daguai, remove one obstacle after another, prove yourself step by step, and finally complete the shopping. The whole process is intense and exciting, beautiful and fun, completely beyond people’s imagination, coupled with the combination of sound and light effects, let people lament that every self-purchase is a science fiction blockbuster.
  In fact, the vending machine is a very precise machine consisting of a circuit board, a coin chute, and a coin sorter. For coins, to complete the shopping, you must pass through several levels of vending machines to prove “who am I.”
  First, coins have to prove themselves by size. To accomplish this task, coins must pass through two light sensors. At this point, all it has to do is spur full horsepower and rush forward without looking back. Normally, the light sensor consists of a diode and a sensor that can receive the light emitted by it. Then, the computer system can accurately determine the size of the coin based on the duration of the coin blocking sensor and the time difference between the two sets of sensor light blocking. So far, all coins that meet the specifications have passed the first pass.
  This also means that invalid coins that want to fish in troubled waters and be recharged will be returned to their origins. For example, the diameter of a dollar coin is 25 mm, the pentagon coin is 20.5 mm, and the dime coin is 22.5 mm. If the size does not match, it will be recognized as an invalid coin and thrown into the refund port.
  In the second hurdle, coins will prove themselves by their color and texture. At this time, the coin passes through two copper coils. There is current in these copper coils, and a magnetic field is formed around them, which becomes an electromagnet. The coin will cut this magnetic field during the crossing, and then change the magnitude of the current in the copper coil. For example, the yuan coin is made of copper-nickel alloy, and the pentagon coin is copper-zinc alloy. Different metals have different effects on the magnetic field in the copper coil. According to the change in current, the circuit board of the vending machine can immediately determine what the metal contained in the coin is. Therefore, all invalid coins with different materials have to be eliminated.
  After completing the above two steps, the coin is finally determined to be “own”. The face value of the coin was calculated in less than a second. Then in the call of “come to my bowl”, the coins of one yuan, five cents and one cent are happily led to the corresponding coin slot. If a change is needed, the coin slot will carefully release coins, only one coin at a time, until the change is completed.
  There is also a secret in the vending machine. The goods we see are actually samples. What we buy is not these samples, but the goods placed in the vending machine warehouse. So, now it’s time for the spring freight lane to show its talents. There is a button under each item. After receiving the instruction, the spring goods lane will push the corresponding item forward. The most “technological sense” is that before the product comes out, it must pass through a layer of grating composed of 10 far-infrared beams, which is exactly the same as the line of defense in Hollywood blockbusters. After that, as the goods dropped smoothly, the shopping was completed.
  However, with the development of technology, payment methods have become increasingly diversified, and now WeChat payment has been widely used. Perhaps one day in the future, self-service coin shopping will become history. Of course, the science fiction blockbuster we saw may be a different look.