Electromagnetic oven system for automatically heating variable numbers and sizes of food items or the like

Claim 3

The system set fourth in claim 1 including: guide means in the cavity; an article carrier removably positioned in the cavity by said guide means; and means mounting said sensor unit on the article carrier so that said sensor is coupled to said control unit when said article carrier is positioned by said guide meame.

Claim 4

The system set forth in claim 1 in which said control unit includes a magnetically controlled switching means, and said sensor unit includes a magnetic material magnetically coupled to said switching means.

Claim 9

A system as defined in claim 5 in which the sensor is a magnetic member and in which the detecting means and the sensor are magnetically coupled when the article carrier is in a proper position within the cavity and the initiating of heating of the oven is inhibited when the sensor is not coupled to the detecting means.

Claim 10

A system as defined in claim 6 in which the detecting means includes magnetized means magnetically coupled to the magnetic member when the article carrier is properly positioned in the cavity.

Claim 11

An automatic system for heating items varying in size using electromagnetic energy, said system comprising: a chamber within which electromagnetic heating is to take place; a magnetic field which, at least in part, passes through a wall of said chamber; a sensor having ferromagnetic properties at normal temperatures and paramagnetic properties at elevated temperatures and having electromagnetic absorption properties which cause it to become hot when exposed to the electromagnetic energy that is sometimes present within said chamber; a fixed location within said chamber where said sensor may be placed within said magnetic field whenever at least one item is to be heated in said chamber; magnetic field strength detecting means positioned outside of said chamber adjacent said wall and within said magnetic field for generating a signal whenever the strength of the magnetic field indicates that a sensor having ferromagnetic properties is present at said fixed location; and means for supplying electromagnetic energy to the interior of said chamber under the control of said signal; whereby said sensor, when placed into said chamber along with said item, automatically causes said means for supplying energy to heat said item for a period of time proportional to the energy absorbed by said item.

Claim 12

An automatic system for heating items varying in size using electromagnetic energy, said system comprising: a chamber within which electromagnetic heating is to take place; a magnetic field which, at least in part, passes through a wall of said chamber; a sensor having ferromagnetic properties at normal temperatures and paramagnetic properties at elevated temperatures and having electromagnetic absorption properties which cause it to become hot when exposed to the electromagnetic energy that is sometimes present within said chamber; a fixed location within said chamber where said sensor may be placed within said magnetic field whenever at least one item is to be heated in said chamber; magnetic field strength detecting means positioned outside of said chamber adjacent said wall and within said magnetic field for generating a signal whenever the strength of the magnetic field indicates that a sensor having ferromagnetic properties is present at said fixed location; and means for supplying electromagnetic energy to the interior of said chamber under the control of said signal; whereby said sensor, when placed into said chamber along with said item, automatically causes said means for supplying energy to heat said item for a period of time proportional to the energy absorbed by said item.

Claim 13

An automatic system in accordance with claim 8 wherein said magnetic field strength detecting means comprises a switch having magnetic contacts arranged to open and close in response to changes in the strength of the magnetic field adjacent said switch, and wherein said signal is represented by the presence or absence of current flow through said switch.

Claim 14

An automatic system in accordance with claim 9 which includes a magnetic member, and means for adjustably positioning said member relative to said switch.

Claim 15

A automatic system in accordance with claim 8 wherein said magnetic field strength detecting means comprises a magnet which also generates said static magnetic field and means for generating said signal in response to a motion of said magnet towards said fixed location.

Claim 16

An automatic system in accordance with claim 11 wherein said means for generating said signal comprises a switch arranged to be actuated by the motion of said magnet.

Claim 17

An automatic system in accordance with claim 12 wherein said switch is a mercury switch and which includes means for rotating said mercury switch in response to motion of said magnet.

Claim 18

An automatic system in accordance with claim 8 to which is added a counter means for counting the number of times said signal is generated, and signalling means controlled by said counter means for indicating when said signal is generated a predetermined number of tiMes, but not less than twice.

Claim 19

An automatic system in accordance with claim 14 wherein said chamber has a door and wherein means are provided for resetting said counter when said door is actuated.

Claim 20

An automatic system in accordance with claim 15 wherein additional means are provided for defeating the action of said resetting means if said signal is not present when said door is actuated, thereby preventing the resetting of said counter when a sensor is not present within said chamber.

Claim 21

In an electromagnetic oven, the combination of, means defining cavity in which articles to be heated are placed; a source of electromagnetic energy for said cavity; an energy sensor positioned where it is exposed to the electromagnetic energy generated by said source, said sensor having ferromagnetic properties at low temperatures and paramagnetic properties at elevated temperatures, and said sensor being capable of absorbing energy at a rate which is proportional to the energy absorption of an article which is also exposed to electromagnetic energy generated by said source so that said sensor changes from a predominantly ferromagnetic state to a predominantly paramagnetic state when the article to be heated reaches a predetermined temperature; magnetic-property detector means positioned adjacent said sensor for generating a signal whose state indicates whether said sensor is predominantly ferromagnetic or paramagnetic; and means responsive to said signal for placing said electromagnetic energy source into operation when the state of said signal indicates that said sensor is predominantly ferromagnetic and for shutting down said electromagnetic energy source when the state of said signal indicates that said sensor is predominantly paramagnetic.

Claim 22

In an electromagnetic oven, the combination of, means defining cavity in which articles to be heated are placed; a source of electromagnetic energy for said cavity; an energy sensor positioned where it is exposed to the electromagnetic energy generated by said source, said sensor having ferromagnetic properties at low temperatures and paramagnetic properties at elevated temperatures, and said sensor being capable of absorbing energy at a rate which is proportional to the energy absorption of an article which is also exposed to electromagnetic energy generated by said source so that said sensor changes from a predominantly ferromagnetic state to a predominantly paramagnetic state when the article to be heated reaches a predetermined temperature; magnetic-property detector means positioned adjacent said sensor for generating a signal whose state indicates whether said sensor is predominantly ferromagnetic or paramagnetic; and means responsive to said signal for placing said electromagnetic energy source into operation when the state of said signal indicates that said sensor is predominantly ferromagnetic and for shutting down said electromagnetic energy source when the state of said signal indicates that said sensor is predominantly paramagnetic.

Claim 23

A control system in accordance with claim 17 wherein the detector means comprises s source of magnetic field and a magnetically actuatable switch located within said field.

Claim 24

A control system in accordance with claim 17 wherein the detector means comprises a magnet, an electrical switch, a mounting for said magnet which permits said magnet to move towards and away from said sensor, means for normally biasing said magnet away from said sensor, and means for actuating said switch in response to motion of said magnet.

Claim 25

A control system in accordance with claim 17 to which is added means for counting, means for advancing said means for counting in response to the fluctuations of said signal, and signalling means for signalling when said means for counting reaches a predetermined count.

Claim 26

A control system in accordance with claim 17 to which is added means for measuring the energy level within said heating system and means for lowering the energy level within said heating system when said measuring means signals that the energy level generated by said system is excessively high.

Claim 27

In an electromagnetic oven, the combination of: a source of electromagnetic energy for said oven, an energy sensor capable of absorbing electromagnetic energy from a location at which the level of electromagnetic energy varies inversely with the amount of electromagnetic energy absorbed by material placed in the oven to be heated so that said sensor absorbs electromagnetic energy at a rate which is proportional to the rate at which the material to be heated changes in temperature, means including said energy sensor for developing a control signal having a first value when the energy absorbed by said sensor is below a predetermined value corresponding to a desired condition of the material to be heated and having a second value when the energy absorbed by said sensor is above said predetermined value, and oven control means controlled by said control signal for deactivating said source of electromagnetic energy when said control signal has said second value.

Claim 28

In an electromagnetic oven, the combination of: a source of electromagnetic energy for said oven, an energy sensor capable of absorbing electromagnetic energy from a location at which the level of electromagnetic energy varies inversely with the amount of electromagnetic energy absorbed by material placed in the oven to be heated so that said sensor absorbs electromagnetic energy at a rate which is proportional to the rate at which the material to be heated changes in temperature, means including said energy sensor for developing a control signal having a first value when the energy absorbed by said sensor is below a predetermined value corresponding to a desired condition of the material to be heated and having a second value when the energy absorbed by said sensor is above said predetermined value, and oven control means controlled by said control signal for deactivating said source of electromagnetic energy when said control signal has said second value.

Claim 29

A control system in accordance with claim 22 wherein a plurality of sensors are provided, and each of said sensors changes from A predominantly ferromagnetic state to a predominantly paramagnetic state at said predetermined value of absorbed energy, whereby a fresh sensor may be placed within the oven adjacent the means for detecting each time the oven is used.

Claim 30

A control system in accordance with claim 22 wherein said oven includes an adjustable source of electromagnetic energy and means indepdendent of said sensor for lowering the output of said source whenever the energy level within said oven rises above a predetermined threshold level.

Claim 31

A control system in accordance with claim 22 wherein said oven is designed to accept trays, wherein said oven includes an adjustable source of electromagnetic energy, and wherein said control system includes means for lowering the output of said source in response to the insertion of trays having particular properties into the oven.

Claim 32

A control system in accordance with claim 22 wherein the oven system includes a counter arranged to count fluctuations of said signal and to initiate a control action after a fixed number of fluctuations occur.

Claim 33

A control system in accordance with claim 22 wherein the oven system includes a signalling device and a counter arranged to count fluctuations of said signal and to energize said signalling device after a fixed number of fluctuations are counted.

Claim 34

A control system in accordance with claim 22 wherein said means for developing said control signal is arranged to generate said first value of control signal whenever said sensor is not positioned at said location so that said oven cannot be operated without said sensor being present.

Claim 35

In an electromagnetic oven, the combination of: a cavity in which items to be heated are placed; a source of electromagnetic energy for said cavity, an energy sensor-detector unit having a property which changes from a first state to a second state at a predetermined operating point, said energy sensor-detector unit being capable of absorbing energy from said source at a rate which is proportional to the rate at which an item to be heated increases in temperature, so that said sensor-detector unit changes from said first state to said second state when said item to be heated reaches a predetermined temperature, and control means responsive to said energy sensor-detector unit for deactivating said source of electromagnetic energy when said energy sensor-detector unit changes from said first state to said second state.

Claim 36

In an electromagnetic oven, the combination of: a cavity in which items to be heated are placed; a source of electromagnetic energy for said cavity, an energy sensor-detector unit having a property which changes from a first state to a second state at a predetermined operating point, said energy sensor-detector unit being capable of absorbing energy from said source at a rate which is proportional to the rate at which an item to be heated increases in temperature, so that said sensor-detector unit changes from said first state to said second state when said item to be heated reaches a predetermined temperature, and control means responsive to said energy sensor-detector unit for deactivating said source of electromagnetic energy when said energy sensor-detector unit changes from said first state to said second state.

Claim 37

A control system in accordance with claim 29 wherein the said property of the sensor is a temperature-dependent magnetic property, said sensor having a ferromagnetic property at lower temperatures and a paramagnetic property when heated to beyond a critical temperature level.

Claim 38

A control system in accordance with claim 30 wherein said means for detecting comprises a source of magnetic field and a field-strength-responsive signalling device both located in the vicinity of said energy sensor.

Claim 39

A control system in accordance with claim 31 wherein said signalling device comprises a reed switch having magnetically actuatable contacts.

Claim 40

In a microwave oven adapted to receive trays on which items to be heated may be placed and successively positioned within said oven, the combination of, a sensor carried by one of said trays, said sensor having a characteristic which varies from a first state to a second state in response to the absorption of a predetermined amount of electromagnetic energy, said sensor having said first state when the tray on which it is placed is initially placed in said oven, means for positioning said tray within said oven so that said sensor is at a predetermined location within said oven where it can receive electromagnetic energy, detecting means positioned to detect the presence of a sensor at said predetermined location and arranged to develop a control signal having a first value when said sensor has said first state and a second value when said sensor has said second state, and means cOntrolled by said control signal for supplying electromagnetic energy to said oven only during periods when said control signal has said first value.

Claim 41

In a microwave oven adapted to receive trays on which items to be heated may be placed and successively positioned within said oven, the combination of, a sensor carried by one of said trays, said sensor having a characteristic which varies from a first state to a second state in response to the absorption of a predetermined amount of electromagnetic energy, said sensor having said first state when the tray on which it is placed is initially placed in said oven, means for positioning said tray within said oven so that said sensor is at a predetermined location within said oven where it can receive electromagnetic energy, detecting means positioned to detect the presence of a sensor at said predetermined location and arranged to develop a control signal having a first value when said sensor has said first state and a second value when said sensor has said second state, and means cOntrolled by said control signal for supplying electromagnetic energy to said oven only during periods when said control signal has said first value.

Claim 42

The combination of claim 33, wherein said sensor is predominantly ferromagnetic when in said first state and is predominantly paramagnetic when in said second state, and said detecting means is magnetically coupled to said sensor when said tray is positioned within said oven.

Claim 43

The combination of claim 33, which includes means for counting the number of times electromagnetic energy is applied to said oven while the same sensor is positioned at said predetermined location.

Claim 44

The combination of claim 35, which includes means controlled by said counting means for producing a second control signal, and indicating means controlled by said second control signal.

Claim 45

The combination of claim 33, which includes means independent of said sensor and detecting means for developing a second signal proportional to the level of of electromagnetic energy within said oven, said level varying with the amount of energy absorbed by the food on a tray placed within said oven, and means controlled by said second control signal for controlling said electromagnetic energy supply means to reduce the level of electromagnetic energy supplied to said oven when said second signal exceeds a predetermined value.

Claim 46

The combination of claim 37, wherein said electromagnetic energy supply means normally supplies a predetermined level of electromagnetic energy to said oven, means controlled by said second control signal for reducing the level of electromagnetic energy in said oven when a tray having less than a predetermined quantity of food is placed in said oven, and means for restoring said predetermined level when a tray having more than a predetermined quantity of food is placed in said oven.

Claim 47

The combination of claim 37 which includes means for adjusting the value of said second signal at which said reduction in level of electromagnetic energy is made, thereby to adjust the quantity of food which must be present on one of said trays to cause said reduction in energy level.

Claim 48

The combination of claim 33, which includes indicating means, and means operative after a predetermined number of applications of electromagnetic energy to the items on said tray for energizing said indicating means.

Claim 49

The combination of claim 40, which includes means for energizing said indicating means in the event a tray with a sensor in said second state is placed in said oven.

Claim 50

The combination of claim 33, which includes indicating means, and means for energizing said indicating means in the event a tray without a sensor is placed in said oven.