when was the self cleaning oven invented

What is a Microwave Oven?

No one is born to know about Microwave Ovens (MO). We all wake up one day and observe food being inserted into a medium size box in the kitchen to make it hot. I have always wondered how a microwave oven works, who invented it, can you change the colour, will I get one for college and so on.

Needless to say, the microwave oven is a staple in every household and a must-have appliance that has revolutionized all domestic and commercial kitchens around the world. Believe it or not, we use our microwave ovens almost as much as we do our phones (this might be inaccurate, depending on how much warm pizza and bread you can consume within 24 hours). The design of such a fantastic household appliance is such that it relies on electromagnetic radiation to cook all meals as fast and evenly as possible, thanks to the internal heating process used.

The main job of every MO is to help you with all time-consuming cooking tasks, some of which include the melting of your butter for toast and water heating. There are three major types of microwave oven, namely the solo, grill, and conventional ovens, each possessing a unique ability and wide range of accessories that allow you to enjoy your favorite meals warm and free from harm.

What Principle does Microwave Oven operate on?

Electromagnetic Radiation

Just like Ultraviolet Radiation, Radio Waves, Gamma, and X-Rays, microwaves are enlisted as a type of electromagnetic radiation. It exists in a broad range of applications, some of which include radar, communications, and cooking, which is by far the most common application all over the globe. Electromagnetic radiation moves at varying frequencies and wavelengths and is transmitted via particles or waves. The varying wavelengths are often referred to as the electromagnetic spectrum range or the EM, and this spectrum has seven divisions in order of increasing energy and frequency and decreasing wavelength.
Microwaves are often found between infrared light and radio waves, and as such, it is used mostly for point-to-point communication systems for the conveyance of information. Concerning cooking, food is heated or cooked once it is exposed to the electromagnetic radiation found in the microwave frequency range. This produces thermal energy, causing what is known as dielectric heating. Unlike other types of heating, microwaves are known to heat foods quickly and uniformly.

History of Microwave Ovens

The existence of microwaves was known to humanity for decades, but the invention of the microwave oven was by total accident. Since the majority of scientists knew what microwaves could do, the next step was to figure out how these microwaves could serve humans in peace. Only one man asked himself this question and sought to find the most appropriate answer. The invention of the microwave oven happened as World War II came to an end, and it was around this time that the market for magnetron tubes experienced a drastic reduction.

Why was the microwave oven invented

Magnetron tubes, during those times, were being used by the masses to generate microwaves for short-range military radar. The reduction in supply led many scientists like Raytheon, to begin research on new applications for magnetron tubes. Besides the fame and knowledge of microwaves, one other thing that wasn't incredibly new to the world was the idea of heating food with radio waves. In fact, before the invention of the microwave oven, companies such as RCA, Bell Labs, and General Electric were in constant production mode, working on variations of the dielectric heating technology.

Percy Spencer, a Raytheon engineer, was well aware of all their efforts and decided to take the research further after he visited a magnetron lab. Percy Spencer walked into a lab where magnetron tubes and other power tubes of radar sets were undergoing testing. While walking through the process, he felt the peanut bar in his pants pocket begin to cook. Further observation and discussions with present scientists affirmed the occurrence, but Spencer still itched for a deeper understanding.
The next test involved a package of popcorn which he held near a magnetron, and a fresh egg placed within a kettle through a hole Spencer himself cut. The popcorn package exploded all over the lab, while the cooked egg exploded in Spencer's face, the very first microwave cooked egg. Spencer's research escalated after this incident, leading Raytheon to create and launch their first batch of commercial microwave ovens, called the Radarange. Continuous research led to further alterations of the initial microwave oven design until homes and restaurant kitchens were filled with cabinet and countertop microwave ovens that could accommodate all kinds of foods.

The First Microwave Oven (Radarange)

Weight	750 pounds
Size & Dimension	Height:5.9ft & Width: 1.9ft
Price	$5,000
Year	1947

Who Invented The Microwave Oven?

Many wonder the creative genius behind the invention of this must-have kitchen appliance, the microwave oven. As stated earlier in the history of microwave ovens, the oven was first discovered and designed by a Raytheon engineer, Percy Spencer. His entire invention is what one would classify as a unique accident that resulted in something positive and mighty useful for decades to come. While working with Raytheon, Percy Spencer was an engineer who developed microwave radar transmitters during World War II.
The first food he cooked after creating the first working microwave oven was popcorn, which was cooked evenly and quickly since the microwaves penetrated the food speedily and converted all fats and sugars to heat. Percy also observed with his invention that materials such as glass, plastics, and ceramics could not absorb microwaves; thus, all foods can be placed in containers made of these materials and heated without any potential harm coming to the consumer.

          In 1946, Dr. Percy LeBaron invented the first Microwave Oven

Dr Percy LeBaron Spencer was an American self-taught electrical engineer, scientist and inventor who invented the microwave oven, now a household name in many homes.
Born on July 19, 1894 and died on September 8, 1970, Dr Spencer is lived a life of adventure and ingenuity. Many have described his 76 years of life as exceptionally impactful leaving an indelible mark on science.
Unlike most people, Dr Spencer acquired his knowledge and qualification by teaching himself the basics and principles of electricity. This was an intentional attempt to be more useful at his new job with a paper mill. Joining the navy was another challenge as he combined his daily duties with his new found interest in learning about Radio. He quickly realized that he needed to learn maths, physics and chemistry, which he taught himself yet again. He mostly read text books from friends or public libraries as he could not afford all the books needed.

Dr Spencer quickly turn out to be one of the world's top minds in radar tube design. Spencer got a job at a contracting firm for the U.S. Department of Defense – Raytheon. As the leader of the power tube branch, Spencer secured a significant contract with the Government to develop a set of radar facility for the Radiation Laboratory of M.I.T.. Many attributed his fast success to his high level of character and proficiency in his work. The contract was of enormous importance to the Allies of World War II and was considered the military's second biggest in significance during World War II, behind the Manhattan Project.
Spencer eventually assumed the position of the Vice President of Raytheon and later retired in 1964. The sad news of his passing came six years after he left his role at Raytheon. He did not live to see how big his invention will become.
Later in his life, The University of Massachusetts awarded Dr. Percy LeBaron Spencer, a PhD honorary degree for his invention and contribution to science.

What technology drives it?

The common element in all microwave ovens is the magnetron. This part of the microwave oven takes electricity from the power outlet when you set the unit to start cooking. The energy received is transformed into a high-powered radio wave that then penetrates your foods for even cooking. The waves move through a waveguide until it gets to the food, spinning slowly on the oven's turntables. The technology that makes all microwaves so efficient is the bouncing back and forth of waves off the reflective walls of your compartment. Without this process, the microwaves cannot gain contact with your food and penetrate it for perfect preparation.

How does a Microwave Oven work?

The magic of how microwaves turn their electricity into heat is one that leaves many people in awe, except scientists and microwave oven designers, of course. If you've ever wondered exactly how these microwaves work, we are here to show you how!
What we all see on the outside is a sturdy metal box. This box is called a magnetron by scientists, and it is meant to be a microwave generator. Once the microwave is in operation, the magnetron receives energy from a power source, and this energy is then converted into high-powered radio waves. These high-powered waves are approximately 12 cm, equivalent to 4.6 inches.
There is a food channel called the waveguide, and it is through this channel that the magnetron blasts waves into the food compartment. In the food compartment, your food sits comfortably on a turntable, allowing the microwaves to cook it evenly as it spins slowly. Within the walls of the food compartment, the microwaves bounce back and forth, just as light bounces off a reflective surface. All waves bounce off the metallic walls until they hit your food, upon reaching the food itself, the microwaves penetrate inside your food, making the molecules vibrate more quickly.
The faster the molecules vibrate, the hotter your food will become since vibrating molecules have heat. This process happens within a short period, depending on the type of food heating and its state (frozen or non-frozen). Read more about how the Microwave Oven works

Patents on Microwave Ovens

The first patent for the microwave oven was filed by Raytheon, even though Percy Spencer did the design and science. Their license was submitted on October 8, 1945, two years before the company produced its first commercial microwave oven. This machine was called the Radarange, was almost six feet tall, and weighed about 750 pounds (this is about two-thirds as heavy as a Polar Bear). Besides its enormous form, the Radarange was very expensive, since it was the first of its kind. The first microwave oven model cost $5,000, and this lasted for many years before competing brands manufactured significantly cheaper options.

Name of Microwave Oven	Year of active market	Selling price	Cost in today's dollars
Randarange	1947	$5,000	$52,000
Randarange 2.0	1954	$2,000 to $3,000	$20,000 to $30,000
Unknown	1955	$1,295	$9,000
Unknown	1967	$495	$3,500

Since the filing of that first patent, varying designs of microwave ovens can be found all over the world, in restaurant kitchens, convenience stores, and the comfort of our homes. The principal heating operation is still the same but has been modified to be lighter and smaller for easy transport.

Types of Microwave Ovens by Installation

When you consider buying microwave oven, you need to think about the space you have to accommodate it. In terms of structure and installation of Microwave Oven, we have 3 main types of microwave ovens namely the countertop, over-the-range, and the built-in microwaves. We will review these 3 types for better understanding.

Countertop Microwave Oven

The most available and generally inexpensive model is the countertop microwave oven, which many households like because of its simple usage and installation. This type requires no additional cost of installation and certainly movable in the home. Countertop Microwave makes cooking and reheating meals or beverages simple, quick, and convenient.

The Over-The-Range Microwave Oven

Over the range microwaves ovens will naturally help free up space on your counter top by avoiding the big, bulky appliance on limited space in the kitchen. Installing your microwave over your range also gives it a more stable and permanent look.

Built-In Microwave Oven

Built-in microwaves ovens are larger and unlike the countertop microwave is less likely to move around with you. Its installation will need professional hands to accomplish. A built-in microwave oven is usually installed directly above a wall oven or fitted between built-in microwave cabinets.

Types of Microwave Oven by Use

In the land of microwaves, three significant types rule supreme; the solo, grill, and convection microwave ovens. They're listed in order of design and sophistication; thus, the solo microwave oven is the most basic model, followed by the grill and, finally, the convection oven. The differences among these types are based on the model's watts, features, and most importantly, the cost associated.

Solo Microwave Oven

This is the primary entry microwave oven, designed to cook noodles, reheat foods and beverages, and also to defrost frozen meals. It is used commercially and domestically, with its watts converting all energy into heat for the cooking of all foods. Solo microwave ovens can be seen in many areas, from office break rooms to restaurants and small apartments, mainly because it is the most affordable of the three oven types.
Because of the lack of features, and its basic design, the solo microwave is often labeled as a 'microwave.' Some primary uses of this oven include cooking minute rice or pasta, reheating yesterday's dinner, defrosting meat, and heating your coffee. It operates with a watt range of up to 1000 watts, which is the most common wattage for all solo ovens. The price ranges from $50-$300, depending on the capacity, finish, features, watts, and the brand name. Solo microwave ovens have three main finish types, namely stainless steel, plastic, and aluminum.

Grill Microwave Oven

Our second oven type is the grill microwave oven, which is loved by several families around the world. This microwave oven gives your foods the grill taste without needing to use any fire or grill source; thus, it is most suited for grilling your chicken, pizza, and even your fish. Grill microwaves differ from solo ovens because of their additional features and accessories. Their accessories allow the user to grill, roast, and toast foods of their choice within record time.
The grill microwave can be used to cook popcorn, chicken, steak, and even bake your favorite foods. It is more expensive than the solo oven but cheaper than the convection oven. Its price range starts from $85, with the highest price hovering around $600. Some unique features associated with the grill oven include the power grill, solo grill, turntable on/off and eco mode, and the plus combo grill. You can place this microwave oven on your kitchen countertop, or attach it under a cabinet.

Convection Microwave Oven

The convection Microwave is the sleek combination of both the solo and grill microwave ovens. With such a combination in features, this oven allows you to cook all foods enlisted for both oven types, and much more. The significant difference between the convection oven and the two microwave ovens described earlier is that the convection oven uses a fan to operate.
The uses of this convection microwave oven are endless, and as such, its price surpasses both the solo and grill microwave ovens. You can use this oven to make chicken, pizza, popcorn, loaves of bread, and cakes. It is often found in high-end domestic kitchens and many commercial kitchens. Since the cooking technology for this oven is different slightly, its wattage doesn't matter as much as that of the solo, and grill microwaves do.
The highest price for convection ovens stands at $2000, with the lowest level of the spectrum being $180. Some additional features possessed by this oven includes inverter technology, sensor reheating, smarter cooking, and a premium glass door. The convection microwave oven can be placed over the range or built-in to your kitchen space.

Uses of Microwave Ovens

Cooking food
You can cook with your microwave oven, even though most people usually consider their cooktops and stoves only for such a feat. There are multifunctional microwave ovens that allow the use of bake, grill, boil, roast, and steam food items to meet their desired needs. Microwave ovens are very versatile machines that prevent you from buying different kitchen appliances.
Reheating Food
Another use of the microwave oven is to reheat already cooked foods. This is the number one use of the oven around the world. The microwave oven can reheat all meals and ensure that the essential nutrients are retained. The end result is tasty food which isn't too salty or soggy. And the best part? They can be used to reheat any kind of food.
Making fruits juicier
One might find this hard to believe, but it's true. A microwave can help make fruits juicier. This is an excellent use of microwave ovens. To enjoy more succulent fruits, simply place your lemon or orange in the microwave for up to 20 seconds, after which you can squeeze out all the juice you want.
Disinfect kitchen items
Your plastic sponges and cutting boards can be disinfected with help from your microwave oven. The trick is to soak the cutting boards and sponges in lemon juice before heating them for a minute. Microwaves will disinfect your kitchen utensils and deodorize your kitchen in the process.
Proofing yeast
You can proof your yeast in under 15 minutes, instead of waiting for over an hour, with help from your microwave oven. Allow your dough to stand for three minutes and set the microwave for that amount of time. Heat the mixture again for another 3 minutes, allowing it to rest for six minutes. The resting period allows your dough bulk to double.
Heating beauty products
Food aside, the microwave oven helps you look good too! For a splendid application, some beauty products require exposure to a heat source. Microwave ovens make this very simple and less messy. Some beauty products you can heat include your hot oil conditioning packs, facial masks, and reheat gels.

Parts of a Microwave Oven

There are two major systems associated with microwave ovens. These systems are separate but highly connected such that they control all the oven's inner workings. These systems are the control section and the high-voltage section. Besides these two systems, there are other parts of the microwave that help in its operations.

Triac
This is a device that moves electricity from your primary power source to the high voltage system, through your cord. It operates only when the microwave is turned on, thanks to sensors installed within the oven.
High voltage transformer
This is another part of the microwave oven that magnifies the power available to the oven from your home's wiring. The power is then reduced to the needed level for the production of microwaves. The transformer consists of capacitors, which make it a potent part of the oven. From the typical 115 volts in all households, these capacitor loops help produce up to 3000 volts of power for your microwave.
Waveguide
The waveguide is a device that directs and channels all microwaves into the cooking chamber, where your food spins. Before reaching your food, these waves bounce off the inner walls of the oven, with the waveguide being their director.
Frame & Cooking Capacity
The final part we discuss is the deep cavity left for cooking and the box around the cavity. This box is known as the frame, and the deep cavity called the cooking cavity. The oven box is designed such that it keeps all microwaves within the sealed box, with holes that allow the user to see into the cooking cavity, without being affected by the microwaves.

What is the difference between Over-The-Range and Over-The-Counter Microwave Oven?

Over the range microwave ovens are the same as over the counter microwaves. The whole idea is to have your microwave oven installed above your counter top, leaving you more space in the kitchen. Some brands describe this as Over-the-range while others label it as Over-The-Counter.

Glossary

There are several terms often associated with the functioning and use of microwave ovens, many of which relate to cooking, heating, and the preparation of foods.

---------------A – C-----------------------

Additional time settings: Interface pre-programmed to make easy chice of cooking time. Usually designed to be able to add 30seconds to cooking time. Can range from 30 seconds to several number of minutes.

Adjustable sound levels: A sound signal to help in knowing when cooking is done.

Air filter: Installed in over-the-range type of microwaves, the air filter and the built-in exhaust fan help to decrease smoke coming form the coking of various food.

Auto defrost: Automatically uses pre-determined times and power levels to defrost food according to food category and weight.

Auto nightlight: A light installed on the bottom of over-the-range microwaves that illuminates the surface below and is programmable to go on and off at certain times.

Baked goods option: A pre-programmed touchpad for heating, cooking, or defrosting baked goods.

Bi-level cooking rack: A rack that lets you cook more than one item at the same time.

Browning element: An electrical heating feature that makes food to color or brown and crisp during operation.

Built-in: A microwave that is planned to be installed in a cabinet or wall in locations other than above the range.

Capacity: The size of oven cavity measured in cubic feet.

Casserole/stew option: A pre-programmed feature helps to cook casseroles or stews.

Child safety: A safety feature to keep children safe at home by locking the interface panel.

Combination oven: An oven that uses both the cooking functions of a microwave and a convection oven; also called a combi oven or microwave/convection oven.

Convection oven: An electric oven making use of an internal fanning system with an effective approach of uniformly moving hot air to cook food

Cook sensor: A sensor powered by electricity and gauges the level steam or humidity emitted by food in the cavity and is able to determine how much time is needed to cook the food.

Cooking complete reminder: The sound that a microwave makes when it is done cooking food.

Cooktop light: A light installed under an over-the-range microwave that brightens the cooking surface below.

Countertop microwave: A standalone type of microwave that is not installed in a cabinet. – Movable!

Cubic feet: Knowing the operational capacity of a microwave oven is important to making a choice. The cubic feet is the unit of measurement for this and the capacity varies from model to model, typically between 0.6cf and 2.0cf.

---------------D–G------------------------

Defrost sensor option: A sensor that gauges the steam or humidity frozen food lets off and mechanically determines defrosting time.

Delay start: It's a feature that offers you the opportunity to set when you want the microwave to begin operating.

Demo function: As part of the display, some practical ways of operating a microwave are available to be learned via demos and samples.

Dielectric heating: The principle of dielectric heating involves the transformation of the high-frequency electromagnetic field to thermal energy. Dielectric energy is often applied in the crop production area to kill some pests that affect the harvest of the crop. Another use of this heating form is to cook food quickly and evenly.

Display: This is the interface where details such as cooking time, time of the day and date can be shown. Details and forms of display vary from brand to brand.

Distribution: The way the oven dispenses microwaves in the cooking cavity.

Door swing: The opening of the door of the microwave. This could either be designed to close from the left side of from the right side.

Exhaust fan: A fan built into an over-the-range model that is designed to decrease odors and smoke from cooking foods on the range below.

Exhaust or recirculation: It's a feature that is part of over-the-range microwaves or built-in models. In terms of installation, one can deploy an exhaust fan mob up smoke through an outlet to an open space outside the home. Alternatively, smoke can be recirculated and extracted by a filtering system.

Food index menu: A list of foods whose cooking times have been pre-programmed into the control panel in some models.

Fresh vegetable option: A preset feature that cooks vegetable well

Frozen food option: A pre-programmed touchpad for cooking frozen foods.

Griddle: A griddle grill is a great outdoor grill often used to cook a variety of foods. It's user-friendly and considered an ideal option for all light, healthy meals.

---------------h – p-----------------------

Help function: A guide for users that varies from model to model. It may provide helpful instructions for certain functions or let users program certain options.

Hot liquid option: Pre-programmed feature that used for liquids such as tea, coffee or hot chocolate.

Induction Heating: The process of heating an object made from metallic materials using electromagnetic induction is known as induction heating. The heat moves through magnetic fields until it gets to your object, where electric currents are generated for the heating process to begin.

Internal light: The light that is inside of the microwave that goes on or off when the door is opened or closed.

Meat option: Pre-programme feature that was made to cook meat to tasty levels

Message reminder function: A time management tool to keep you close to all appointments and schedules.

Multi-lingual function: Some microwaves have a number of languages that it engages with. It could include Spanish, English, etc

Over-the-range: A built-in microwave, equipped with an exhaust fan, that is designed to be installed above a range or cooktop. Generally, over-the-range microwaves offer both ducted and ductless venting options (see Exhaust or recirculation).

Popcorn preset option: An interface with pre-programmed times to cook a bag of microwave popcorn.

Popcorn sensor: Used to pop corn by releasing enough heat to help in cooking

Power levels: An option of the microwave that release electric power to the device. Usually in increments of 10 and has a lowest number of 10 to as high as 100.

Pre-programmed dishes: There are certain foods that you will naturally find lots of people using the microwave on. Such foods have gained a place in the interface of microwaves. Foods such as rice, pizza or frozen entrees have pre-made times for cooking.

Preheat/warm option: A useful function to help uniformly warm food before eating. The button is preset and effective to use.

Quick start option: A quick and intuitive way of quickly starting a microwave without touching or press the start button. Different microwaves have different digital tools to do this

---------------R – Z-----------------------

Rack: A shelf found in a microwave oven or a combination microwave/convection oven that is intended to enable cookware and increase cooking flexibility.

Recipes menu: A memory system where cooking details are stored up and made available for future cooking.

Reheat: Pre-programme buttons to help in warming of food. Some models may have a "cooking sensor" and others may have a number of preset times.

Repeat function: It captures history of last cooking and presents its as an option to be used for the next cooking activity.

Safety compliance: As the industry is regulated, the safety compliance label signifies that the microwave oven is tested for all the safety and standards provisions. Standards are usually set by Dept. of Health & Human Services and the Federal Communications Commission.

Self-returning turntable: As the name implies, the feature has the ability to bring back the turntable to its original starting point after cooking is done.

Skillet: A skillet is a small metal pot, designed with legs for cooking. A skillet pan has slanted sides, making it the best option for quick cooking techniques such as stir-frying.

Time presets: The device has an estimation of common cooking time and has pre-programmed defined times for use. It may range from 30 seconds to several number of minutes.

Turntable: This is the movable and rotating panel that sits in the cavity of the microwave oven. Its mean role is to ensure evenness in the cooking of food.

Turntable on/off: This is choice of switching the turntable off or on. Usually when it is turned off, there appears to be more space in the cavity of the microwave.

Under-the-counter: A microwave oven installable in the lower part of the counter.

Wattage output: A unit of measurement for the amount of electricity deployed into the system of the microwave. Predictably, higher figures of wattage result in faster cooking of foods.