Microwave ovens are food heating with uhf electromagnetic waves of 2450 mhz, which can travel without damage through plastics, ceramics, metals that cannot be crossed, which reflect, but through water-bearing foods, molecules in the food can friction at high speed, generate heat and make the food warm. In kitchen appliances, microwaves can be said to be the most technocratic appliances, but they do not work in the same way as other appliances and can be seen at once。
Microwaves and light waves in microwaves are two different ways of heating: microwaves heat their own food, and the light waves warm their food from outside like sunlight. The distinction is as follows:
The heating principle is different
Heating directions and effects
Apply scene
In short, microwaves are like "quick cook" and light waves are like "precision roast." now there's a lot of light-wave furnaces that are microwave-photo combinations that combine speed and taste。
The principles of microwave heating food
Microwave means an electromagnetic wave with a frequency of 300 mhz - 300 mhz and a wavelength of 1 mm - 1 m. Microwave frequencies are higher than radio waves, lower than infrared, visible and ultraviolet, and are non-ionising radiation electromagnetic waves。
I. Structures and circuits of microwaves
Microwave furnaces consist of boxes, magnetic tubes, transformers, high-voltage capacitors, high-pressure diodes, radiative fans, rotors and a series of control protection switches, most of which are also equipped with electro-heaters with barbecue functions。
Microcomputer-controlled microwave ovens
Mechanical control microwave ovens
The key element of the microwave is the magnetic tube, which is not visible on household appliances except for the microwave. The main thing is that the magnetic tube cannot be dismantled and that his structure can only be dissected。
There are also “showers” online, and the video can clearly express the internal structure of the magnetic tube。
Magnetic tube light
Magnetic tube anode
The internal structure of the magnetic tube is shown in the figure, and the rationale for its work is shown in the figure below. There is a cylinder cathode inside the magnetic tube, surrounded by an anode outside the cathode, and an axle magnetic field is established through a permanent magnet in an area between the cathode and the anode. When the magnetic tubes are added to the voltage, the cathode is preheated and produces a large number of electrons, which, under the influence of the electric field formed by the high-level differentials between the cathodes and the anodes, as well as by the magnetic field, are orbiting towards the anode. There are a number of small acoustic cavities in the anodes, where electrons convulsate before they reach the anode and form groups of “electronic irradiation”, which rotates at extreme axes (as illustrated by the figure). These vibrating cavities are like a convulsive circuit consisting of a sense of electrons and a convulsive circuit in low-frequency transmitters, and the electronic beams “blowing” through the convulsive cavity form what is called an electronic “wind”, which senses microwaves in the metal cavity. The conversation cavity increases frequency and produces a continuous microwave of 2450 mhz, which is how electronics hand over energy to the uhf electromagnetic field. Microwaves formed during the above-mentioned process enter the cavity of the human microwave through antennas and wave catheters。
In practice, not 100 per cent of the electrons can turn their direct flow energy into microwave energy, and there is always a part of the electron that eventually hits the anodes directly, turning them into thermal energy and warming them. The interaction of magnetic tubes is generally only 70-85 per cent efficient. In order to ensure the stability of the magnetic tubes, the anodes require strong cold or water. In addition, some electrons are unable to participate in energy exchange and return to the cathode, raising the cathode temperature. As a result, the general magnetic controls, after the vibration, need to reduce the heating power of light threads in order to avoid extreme heat and prolong their useful life。
The internal structure is clear, there is no substantial theoretical basis for electromagnetic electron and it is also in the cloud fog, and it is not known how it produces microwaves. It's not like a stone-engineered heater that can see red-hot heaters, it can't see or feel them, but it can cook food, and it's lethal to people。
In order to prevent microwave leaks, the microwaves have taken very strict safety precautions. The microwave has three door switches to prevent microwave injuries. This is due to the fact that the microwave circuits are much more complex because of these three door switches。
Ii. Microwave circuits
This is the circuit chart of the lg microwave (wd 700). Primary switches, monitoring switches, secondary switches are three door-connected micro-switches. Primary switches and secondary switches are the constant-open micro-switches, the micro-switch contacts are disconnected when the furnace door is open, the surveillance switches are the constant-closed micro-switches, and the micro-switch contacts are closed when the furnace door is open。
Electricity status
The doors are closed, primary switches and secondary switches are closed, and the microdynamic switches are disabled; electrical power is plugged into the microwave circuit board, which is also referred to as the “0” on the screen because of the chip on the panel. Figure ry1 is not a regular closed relay, with no return path in the upper or lower state and no light on the stove。
Electricity status
Open the door
When the door was opened, the primary switch cut open the firing line, the secondary switch, the pk, cut off the microwave and barbecue relay circuits, the surveillance was closed and the high-pressure transformer primary loops were cut short, with the aim of preventing an accident from creating microwaves that endangered life. The secondary switch pk was disconnected when the door was opened, the microprocessor received a signal, the drive chip was powered to the ry1 relay loop, the ry1 handle was connected and the stove light was lit. The fan, tray is not working because the primary switch is at a break。
Open the door
Barbecue status
Press the barbeque button in the state of up-to-power, start the button to signal a flash, rotate to start the knob to set the barbecue time, press the start button, ry3 connect, and form the barbecue circuit. The main relay, ry1, is connected, and fans, trays and stove lights work simultaneously. It is worth noting that the tray is driven by a 21v synchronized motor, and that the voltage comes from the ultra-scattered motor wire ring。
Barbecue status
Microwave status
Press the start button in the upper state, or press any other button, and then press the start button by weight or time, and ry2 closes, creating a microwave state. Of these, the light-wire circuit voltage is 3. 3 v. Magnetic tube circuits with a direct flow of 4000 v, which divides the voltage on the second side of the high voltage transformer into a positive and negative half-week analysis. In the first half of a week, high-pressure diode conduits are charged to high-voltage capacitors with a voltage voltage of approximately 2,000 v; in the negative half-week, the high-pressure diode is closed, the high-pressure capacitors are discharged, together with the second side of the voltage superimpose, forming about 4,000 direct current voltages, and the cathode electrons are projected in the direction of reverse currents to form microwaves to the anode。
Microwave status
