Microwave heating apparatus having automatic heating period control

Claim 2

A microwave heating apparatus of the type heating an object in a heating chamber by microwaves, said apparatus comprising: detection means for detecting temperature in the heating chamber, said detection means including a microwave energyabsorbing member disposed in said heating chamber for absorbing a portion of said microwaves, and a detector for detecting a temperature of said microwave energy-absorbing member, said temperature of said microwave energy-absorbing member changing dependent on the quantity of said object, thereby detecting a temperature of said object to be heated, and control means for controlling the supply of microwaves to said heating chamber as a function of the detection of a predetermined temperature of said object by said detection means.

Claim 3

A microwave heating apparatus according to claim 1, further comprising cooling means for reducing the temperature of said microwave energy-absorbing member in said heating chamber to a predetermined level prior to heating a second object to be heated.

Claim 4

A microwave heating apparatus comprising: a heating chamber for containing an object material to be heated; means for generating and supplying microwave energy to said heating chamber for heating the object material; detecting means for detecting a temperature including an energy-absorbing material located within said heating chamber for absorbing a part of said microwave energy in said heating chamber, said energy-absorbing material being heated to a temperature detected by said detecting means upon the absorption of said part of said microwave energy, said part of said microwave energy being inversely dependent on the quantity of said object material; means for generating an electrical signal according to the temperature of said energy-absorbing material; means for generating a reference voltage; means for comparing said electrical signal and said reference voltage so as to generate a control signal when said electrical signal is larger than said reference voltage; and means for applying said control signal to said microwave energy generating means so as to stop the generation of the microwave energy.

Claim 5

A microwave heating apparatus comprising: a heating chamber for containing an object material to be heated; means for generating and supplying microwave energy to said heating chamber for heating the object material; detecting means for detecting a temperature including an energy-absorbing material located within said heating chamber for absorbing a part of said microwave energy in said heating chamber, said energy-absorbing material being heated to a temperature detected by said detecting means upon the absorption of said part of said microwave energy, said part of said microwave energy being inversely dependent on the quantity of said object material; means for generating an electrical signal according to the temperature of said energy-absorbing material; means for generating a reference voltage; means for comparing said electrical signal and said reference voltage so as to generate a control signal when said electrical signal is larger than said reference voltage; and means for applying said control signal to said microwave energy generating means so as to stop the generation of the microwave energy.

Claim 6

A microwave heating apparatus according to claim 3, further comprising: means for cooling said energy-absorbing material; and means for energizing said cooling means when the generation of said microwave energy is stopped.

Claim 7

A microwave heating apparatus according to claim 4, further comprising: means for de-energizing said cooling means when the electrical signal generated by said electrical signal generating means is reduced to a predetermined level.

Claim 8

A microwave heating apparatus according to claim 4, further comprising: means for de-energizing said cooling means when said cooling means has completed a cooling operation for a predetermined period of time.

Claim 9

A microwave heating apparatus according to claim 4, wherein said means for cooling includes: a ventilation flue connected to said heating chamber, a fan for supplying cooling air through said ventilation flue into said heating chamber for cooling said energy-absorbing material so that any effect of the temperature of said energy-absorbing material detecting the temperature of a first object material is eliminated prior to detecting a temperature of a second object material, and a motor operable in response to said control signal for rotating said fan.

Claim 10

A microwave heating apparatus according to claim 7, further comprising: means for generating a second control signal when the temperature of said energy-absorbing material is reduced to a predeteRmined temperature; and means for supplying said second control signal to said motor for stopping the operation of said motor.

Claim 11

A microwave heating apparatus according to claim 3, further comprising: a ventilation flue connected to said heating chamber, a fan for supplying cooling air through said ventilation flue into said heating chamber for cooling said energy-absorbing material so that any effect of the temperature of said energy-absorbing material detecting the temperature of a first object material is eliminated prior to detection of a temperature of a second object material, a motor for rotating said fan; and a switch adapted to be closed by said control signal for a predetermined period of time for supplying a power to said motor to rotate said fan for said predetermined period of time.

Claim 12

A microwave heating apparatus comprising: a heating chamber having a door for containing an object material to be heated; means for generating and supplying microwave energy to said heating chamber for heating the object material; detecting means for detecting a temperature including an energy-absorbing material located within said heating chamber for absorbing a part of said microwave energy in said heating chamber, said energy-absorbing material being heated to a temperature detected by said detecting means upon the absorption of said part of said microwave energy, said part of said microwave energy being inversely dependent upon the quantity of said object material; means for generating an electrical signal according to the temperature of said energy-absorbing material; means for generating a reference voltage; means for comparing said electrical signal and said reference voltage so as to generate a control signal when said electrical signal is larger than said reference voltage; means for applying said control signal to said microwave energy generating means so as to stop the generation of the microwave energy; an arm having a rack the movement of which is operatively associated with the opening and closing of said door of said heating chamber; a pinion being in mesh with said rack of said arm; a fan adapted to be rotated by the rotation of said pinion; means for generating an air flow by the use of said fan; and a ventilation flue for guiding said air flow to said energy-absorbing material from outside of said heating chamber so that any effect of the temperature of said energy-absorbing material detecting the temperature of a first object material is eliminated prior to detection of a temperature of a second object material.

Claim 13

A microwave heating apparatus comprising: a heating chamber having a door for containing an object material to be heated; means for generating and supplying microwave energy to said heating chamber for heating the object material; detecting means for detecting a temperature including an energy-absorbing material located within said heating chamber for absorbing a part of said microwave energy in said heating chamber, said energy-absorbing material being heated to a temperature detected by said detecting means upon the absorption of said part of said microwave energy, said part of said microwave energy being inversely dependent upon the quantity of said object material; means for generating an electrical signal according to the temperature of said energy-absorbing material; means for generating a reference voltage; means for comparing said electrical signal and said reference voltage so as to generate a control signal when said electrical signal is larger than said reference voltage; means for applying said control signal to said microwave energy generating means so as to stop the generation of the microwave energy; an arm having a rack the movement of which is operatively associated with the opening and closing of said door of said heating chamber; a pinion being in mesh with said rack of said arm; a fan adapted to be rotated by the rotation of said pinion; means for generating an air flow by the use of said fan; and a ventilation flue for guiding said air flow to said energy-absorbing material from outside of said heating chamber so that any effect of the temperature of said energy-absorbing material detecting the temperature of a first object material is eliminated prior to detection of a temperature of a second object material.