Every conscientious historian who has been interested in the development of technological progress knows very well that the theory of using microwaves to heat food appeared in the mid-1920s. However, Percy Spencer, an American from Massachusetts, was the first to receive a patent for a microwave oven for defrosting and heating food on October 8, 1945. This date is considered the birthday of the microwave oven. According to a widespread legend, the idea for this useful invention came to the scientist at the moment when a chocolate bar unexpectedly melted in his pocket. Surprised, Spencer began to look for the cause of the unpleasant emergency and soon realized that the reason for such incorrect behavior of the chocolate bar was the magnetron near which he was standing. As is known, this particular device generates microwave electromagnetic radiation. A worthy legend for an invention useful in the household, which was quickly adopted by military canteens and large restaurants. It should be noted that the first microwave ovens were large and heavy. With a height of about two meters, their weight reached about 340 kg. Those microwave ovens to which we are accustomed began to appear in the West only in the 1960s, and in the USSR from the second half of the 1970s. However, the modern historiography of the appearance of the first microwave ovens is not reliable. In fact, they were invented in the USSR on the eve of the Great Patriotic War.
Today, many families use a microwave oven, and it’s difficult to surprise anyone with this device at work. It is affordable and not a luxury, it is small in size, convenient and easy to use. But it wasn't always like this. We offer a brief historical excursion into the creation of the microwave oven. It’s interesting what a microwave was like in its original form.
Who invented the microwave
There is no agreement on this issue to this day. Russia and the United States dispute the authorship of the microwave oven, however, the patent belongs to the inventor from the United States.
Historians' versions of who invented the microwave oven
One of the most plausible versions sounds like this: the American engineer and inventor Percy LeBaron Spencer once, during experimental work with a magnetron, discovered that a chocolate bar in his pocket had melted during the work. There is also a version that he placed a sandwich on the magnetron, and then discovered the heating of food while the device was operating. It is likely that during the experiments he received a burn, but when he received a patent for the invention of a microwave oven, he decided to keep silent about it so as not to spoil the image of his brainchild.
Another version set out in the newspaper Trud for 05/17/2011, states that back on June 13, 1941, on the pages of the same newspaper, a device was described that used ultra-high-frequency currents to process meat products. The development was allegedly carried out in the magnetic wave laboratory of the All-Union Research Institute of the Meat Industry.
There are also versions about German developments during the Third Reich, which fell into the hands of scientists from the USSR and the USA. But they never received confirmation.
Patent for the invention of a microwave oven
A patent for a prototype microwave oven was issued in 1946. It was called “Radarange”, its first release dates back to 1947, and was used to quickly defrost food products. It was used only by military personnel in canteens and hospitals.
Interesting to know!
The first microwave was about 180 cm in height and weighed about 340 kg. The power consumption was twice that of modern analogues and consumed 3 kW, its cost was quite high - 3 thousand dollars.
Serial production of the above model began in 1949. The first household microwave oven for the general public was created by the Tappan Company in 1955. Serial production of household microwave ovens dates back to 1962, it was established by the Sharp company, Japan. The new product was met with distrust and did not gain much popularity.
In the Soviet Union, the beginning of mass production of microwave ovens dates back to the early 80s. years of the last century. They were produced by ZIL, YuzhMash, the Elektropribor plant (Tambov), and the Dnieper Machine-Building Plant named after V.I. Lenin.
Who invented the microwave: the USSR or America?
As already written above, it is not possible to accurately establish the authorship of the invention. The fact is that in 1941 the Soviet Union was drawn into the most difficult and bloody war in history, and everyone simply had no time for invention. According to existing international rules, authorship is recognized by the one who received the patent. Therefore, the official author of the microwave oven is Percy LeBaron Spencer from the USA.
Microwave: from the time of invention to the present day
Since the creation of the first models to this day, the appearance of the microwave oven has changed a lot - it has become more compact, more convenient to use, and a lot of useful functions have appeared:
- The calling card of any microwave oven is the rotating tray, which appeared in 1962 thanks to the developments of the Japanese company Sharp.
- The microprocessor that controls the operation of the microwave began to be used for the first time in 1979.
- At the end of the 90s. Since the last century, models have appeared in which the device is controlled by a built-in microcomputer, and at the same time grill and convection functions appeared.
Panasonic has introduced another innovation - inverter microwave ovens. Unlike conventional models, where the magnetron is powered by a transformer, in inverter furnaces the power is supplied through an inverter that converts direct current into alternating current. As a result, the food being heated has a controlled, gentler effect, allowing it to be heated evenly. In addition, the inverter is smaller in size than the transformer, which also makes it possible to reduce the weight and dimensions of the device, which has already become compact compared to the first prototypes, which weighed more than three hundred kilograms and were not inferior in size to a large refrigerator.
Note!The first models of microwave ovens weighed about 300 kg.
Modern stoves, unlike the initial ones, are equipped with a timer that allows you to automatically turn off the device at the right time. Thus, you do not need to monitor the microwave oven as before; it will turn itself off after a certain time and beep.
In a word, progress does not stand still, and many companies compete with each other for the sales market, offering the buyer more and more new models with different functions. Despite the emergence of many different innovations, the principle of operation of the microwave has not changed since its invention. It still uses ultra-high frequency currents to heat and cook food.
In the early forties of the 20th century, American physicist-researcher P. Spencer discovered during experiments that microwave radiation has a thermal effect. While working in an industrial laboratory, Spencer tested a microwave emitter. One day, as is typical for many scientists, he put a sandwich on the installation. Great was his surprise when, after a few minutes, the sandwich turned out to be heated!
Another version of the story of the discovery of the thermal effects of ultra-high-frequency waves says that the scientist carried a chocolate bar in his pocket, which melted due to the operation of the installation.
More than three years later, the scientist received a well-deserved patent for the use of microwave radiation for cooking purposes. This happened in October 1945. And by the end of the forties, the first microwave ovens appeared in US canteens. But the device was very bulky and weighed quite a lot. A wide field of activity opened up for inventors to improve the microwave oven.
Success came to Japanese designers who worked hard to refine Spencer's invention for a decade and a half. A more modern design of the furnace was developed; the device received a rotating plate inside. In 1979, the first microwave oven appeared with a built-in microprocessor control system.
How does a microwave oven work?
The design of a microwave oven is simple and complex at the same time. Inside the device there is a transformer, a waveguide and a magnetron, which is a vacuum device that generates waves. To generate the required voltage, the furnace is equipped with.
The device is cooled through a fan that blows an air stream over the magnetron.
From the magnetron, microwaves go into a waveguide channel that has metal walls that can reflect radiation. After passing through the mica filter, the waves enter the furnace chamber. The internal cavity of the oven is usually made of metal and is sometimes covered with paint that imitates enamel. More expensive models are equipped with a coating made of , which is relatively easy to wash off dirt and can withstand thermal effects.
A modern microwave oven differs significantly from its prototype. It is compact, economical and multifunctional. Today, in a microwave oven you can not only heat food, but also defrost it using one of several programmable modes. There are models with a built-in grill that are popular. It is quite possible that in pursuit of consumer attention, inventors will add many more useful functions to the stove.
It's quite simple. The phenomenon of heating by microwave or microwave electromagnetic radiation (usually with a frequency of 2.45 GHz) of substances containing water, or more precisely, its dipole molecules (at one end there is a positive charge and at the other - a negative charge) is used.
Microwave, or ultra-high frequency (microwave), radiation is electromagnetic waves with a length of 1 millimeter to 1 meter. Let us note that these waves also exist in nature; they are emitted by the Sun. The wavelength in a microwave oven is 12.25 cm.
Direct heating of the products occurs due to the very rapid movement of molecules under the influence of electromagnetic radiation, microwaves generated by a special emitter - a magnetron - and entering the working chamber through a sealed metal waveguide.
The electromagnetic field in which food molecules are located changes polarity almost five billion times per second, which causes the molecules to “tumble” at breakneck speed, and heat is released from friction between them.
Appearance versions
Precisely versions, because there are several of them. In addition to the official, “American” one, there are others that are less often remembered.
Daddy Spencer
Percy LeBaron Spencer is an American engineer who worked in the forties of the twentieth century at Raytheon, which is still alive and well today - the Pentagon's largest supplier, developer and manufacturer of Patriots and Tomahawks.
Spencer was then engaged in the development and manufacture of radars and their components, and one day, as it later turned out, for housewives all over the world, while testing another magnetron (microwave generator), he noticed how hot the sandwich, for some reason lying on the working device, became very hot.
cooking" magnetron at one of the meetings on Raytheon's entry into the consumer market and received approval from management. So the microwave is more likely the fruit of systematic work than an accident.
The method of cooking food using microwaves was patented (patent number - 620.919), and in 1947 Raytheon introduced the first microwave oven - the Radarange. It weighed more than 300 kg, was 180 cm high, had a power of 3000 W (almost three times more than modern models), was water-cooled and cost a huge amount of money at the time - $5000 (multiply by 10–11 and get the equivalent price nowadays).
The product was clearly not mass produced. Initially, the oven was purchased by the same US Department of Defense - for quickly defrosting food in soldiers' canteens and in the kitchens of military hospitals. Hotel and restaurant owners also showed some interest in Radarange and installed them in ship galleys.
Japanese trace
The Japanese also had a hand in “microwave cooking”. In fact, they even overtook the Americans by starting mass production of the Sharp R-10 in 1962 (demand, however, was sluggish), while in the States the first mass model appeared five years later. In 1966, Sharp developed the now familiar turntable, which significantly improved the quality of cooking and defrosting food. In 1979, the same company presented the first microwave oven with microprocessor control, and in 1999 - with access to the Internet .
Made in the USSR
There is also an opinion that the birthplace of the microwave is the Soviet Union. Relatively recently, on May 17, 2011, the Trud newspaper reported that just before the start of the Great Patriotic War, on June 13, 1941, it published a note “A new method of cooking meat,” which described the installation developed at the All-Union Research Institute of Meat Industry for heat treatment meat products, using ultra-high frequency currents for this purpose.
It was a kind of prototype of a microwave oven. Perhaps, if the war had not happened a little over a week later, our country would still be considered its homeland. But everything turned out differently, and after the war the USSR had no time for microwaves.
However, much later, in the 80s of the twentieth century, our country had its own production of microwave ovens from Japanese components: at the ZIL (Moscow) and Yuzhmash (Donetsk) factories.
Alien visitor
For dessert - a version about the alien origin of the microwave oven. There is one. According to it, the technology was borrowed by the Americans from aliens as a result of the famous Roswell incident. In 1947, an alleged UFO crashed or was shot down in New Mexico (the US Air Force does not officially confirm this when talking about a weather balloon). And there, on board an alien ship, along with immediately classified aliens, they allegedly found our heroine - a microwave oven, in any case, the technological solutions that formed the basis of her work.
Of course, there is no official confirmation of this version. The Roswell incident is now more of a part of American pop culture, although there are still debates about how it really happened, whether it was aliens or a secret military experiment.
Massive conquest of kitchens
Microwaves took their first steps into American homes in 1955, when local household appliance manufacturer Tappan (later purchased by Electrolux), using Raytheon's own developments and technologies, introduced a version of the microwave oven for home use. But these steps are still timid - the device still turned out to be cumbersome, still unclear to Americans, and although it was cheaper, it was still expensive for those times - $1,295.
The American company Litton Industries (still exists today - the largest manufacturer of military equipment in the United States) also did a lot in the middle of the last century to promote microwave ovens to the masses. It is Litton that we owe for the appearance of models of the format that is now considered a classic: small in height, but relatively wide and deep.
The first truly popular microwave appeared in the United States in 1967 and was a joint product of Raytheon and Amana. It cost about 400 dollars. It was 50 years ago that the microwave boom began in the United States. By 1975, sales of microwave ovens were already about 1 million units per year.
At first, Japan was ahead of the United States in percentage terms in the distribution of microwave ovens. In the early 70s, already 17% of Japanese families used a microwave oven every day at home, and in the USA - only 4%. But within a few years, such stoves were working in the kitchens of 14% of American families. By the end of the seventies, it was already in more than 50% of kitchens in the United States and overtook the dishwasher in popularity.
Main components of magnetron microwave oven:
- a metal chamber with a metallized door (in which high-frequency radiation is concentrated, for example 2450 MHz), where the heated products are placed;
- transformer - source of high-voltage power supply for the magnetron;
- control and switching circuits;
- direct microwave emitter - magnetron;
- a waveguide for transmitting radiation from the magnetron to the camera;
- auxiliary elements:
- rotating table - necessary for uniform heating of the product from all sides;
- circuits and circuits that provide control (timer) and safety (mode locking) of the device;
- fan cooling the magnetron and ventilating the chamber.
Varieties
Based on the type of design, microwave ovens are divided into:
- solo- only microwave radiation; without grill and convection.
- with grill- contains a built-in quartz or heating element grill.
- with convection- a special fan forces hot air into the chamber, thereby ensuring more uniform baking, similar to an oven.
Based on the type of control, microwave ovens are divided into:
- mechanical- mechanical time and power regulators are used.
- push-button- the control panel consists of a set of buttons.
- sensory- touch-type buttons are used.
Story
Precautions for use
Microwave radiation cannot penetrate metal objects, so it is impossible to cook food in metal utensils.
It is undesirable to place dishes with a metal coating (“golden border”) in a microwave oven - even this thin layer of metal is highly heated by eddy currents, which can destroy the dishes in the area of the metal coating.
Do not heat liquids in a microwave oven in hermetically sealed containers and whole bird eggs - due to the strong evaporation of water, high pressure is created inside them and, as a result, they can explode. For the same reasons, it is not advisable to overheat sausage products covered with plastic film (or pierce each sausage with a fork before heating).
It is forbidden to turn on an empty microwave. You need to at least put a glass of water in it.
When heating water in the microwave, you should also be careful - water is capable of overheating, that is, heating above the boiling point. A superheated liquid can boil almost instantly from careless movement. This applies not only to distilled water, but also to any water that contains few suspended particles. The smoother and more uniform the inner surface of the water container, the higher the risk. If the vessel has a narrow neck, then there is a high probability that when it starts boiling, superheated water will spill out and burn your hands.
Security Issues
Electromagnetic safety
There is extensive evidence to support the dangers of microwave ovens for electronic devices. Microwave radiation during operation of the oven (in the event of a malfunction or leakage of the chamber), coming out, can interfere with the operation of semiconductor chips (leading to their malfunction) and even disable them. There are even known cases where microwaves were used to knock ballistic missiles off course by pointing a working microwave with the door open at them. [ ]
Federal sanitary rules, norms and hygienic standards
Permissible levels of EMF in the frequency range 30 kHz - 300 GHz for the population (in residential areas, in places of public recreation, inside residential premises) 10 μW/cm².
