CA1111505A - Microwave oven having a radiation leak-proof drawer type door - Google Patents
Microwave oven having a radiation leak-proof drawer type doorInfo
- Publication number
- CA1111505A CA1111505A CA300,742A CA300742A CA1111505A CA 1111505 A CA1111505 A CA 1111505A CA 300742 A CA300742 A CA 300742A CA 1111505 A CA1111505 A CA 1111505A
- Authority
- CA
- Canada
- Prior art keywords
- rack
- heating chamber
- door
- microwave oven
- microwave
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000005855 radiation Effects 0.000 title 1
- 238000010438 heat treatment Methods 0.000 claims abstract description 71
- 239000000463 material Substances 0.000 claims abstract description 10
- 239000003989 dielectric material Substances 0.000 claims description 5
- 230000008878 coupling Effects 0.000 claims description 4
- 238000010168 coupling process Methods 0.000 claims description 4
- 238000005859 coupling reaction Methods 0.000 claims description 4
- 239000011810 insulating material Substances 0.000 claims description 2
- 230000002093 peripheral effect Effects 0.000 claims description 2
- 230000000284 resting effect Effects 0.000 claims description 2
- 229910001220 stainless steel Inorganic materials 0.000 claims description 2
- 239000010935 stainless steel Substances 0.000 claims description 2
- 239000011521 glass Substances 0.000 description 9
- 238000010276 construction Methods 0.000 description 8
- 230000002265 prevention Effects 0.000 description 6
- 239000002184 metal Substances 0.000 description 5
- 238000005485 electric heating Methods 0.000 description 4
- 230000002035 prolonged effect Effects 0.000 description 3
- 230000003014 reinforcing effect Effects 0.000 description 3
- 230000002411 adverse Effects 0.000 description 2
- 239000002885 antiferromagnetic material Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000000875 corresponding effect Effects 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 238000005192 partition Methods 0.000 description 2
- 230000003449 preventive effect Effects 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 101100124609 Caenorhabditis elegans zyg-12 gene Proteins 0.000 description 1
- 208000027418 Wounds and injury Diseases 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000001808 coupling effect Effects 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000010892 electric spark Methods 0.000 description 1
- 230000005672 electromagnetic field Effects 0.000 description 1
- 239000002320 enamel (paints) Substances 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 208000014674 injury Diseases 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/72—Radiators or antennas
- H05B6/725—Rotatable antennas
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/6414—Aspects relating to the door of the microwave heating apparatus
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/76—Prevention of microwave leakage, e.g. door sealings
- H05B6/763—Microwave radiation seals for doors
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/76—Prevention of microwave leakage, e.g. door sealings
- H05B6/766—Microwave radiation screens for windows
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Electric Ovens (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A microwave oven has an oven-defining structure with an access opening leading into a heating chamber. A
drawer type door assembly of substantially L-shaped con-figuration includes a door structure adapted to close and open the access opening. A rail structure is movably supported to facilitate the movement of the door structure between closed and opened positions. A power source transmits microwave energy into the heating chamber. Hook members each have a plurality of hooks for the support of a rack to support a material to be heated. The oven may further include a tray by which the material to be heated is mounted on the rack. The door structure is designed to assume a parallel relation to the plane of the access opening when moved between closed and open positions.
A microwave oven has an oven-defining structure with an access opening leading into a heating chamber. A
drawer type door assembly of substantially L-shaped con-figuration includes a door structure adapted to close and open the access opening. A rail structure is movably supported to facilitate the movement of the door structure between closed and opened positions. A power source transmits microwave energy into the heating chamber. Hook members each have a plurality of hooks for the support of a rack to support a material to be heated. The oven may further include a tray by which the material to be heated is mounted on the rack. The door structure is designed to assume a parallel relation to the plane of the access opening when moved between closed and open positions.
Description
The present invention generally relates to a micro-wave oven and, more particularly, to a microwave oven comprising an oven-defining structure having an access opening leading into a heating chamber and a drawer type door assembly for selectively closing and opening the access opening.
A recent development of microwave oven is a type adapted to be installed on a floor, for example, a kitchen floor, which may be referred to as a base-board model.
Of the various base-board models now commercially available, one having a drawer type door assembly of substantially L-shaped construction including a horizontally extending support base structure and a vertically extending door structure is considered convenient and easy to handle, since both the door structure and the support base structure (with or without a rack for the support of a material, for example, a food item, to be heated ) can be simultaneously moved out of the oven-defining structure with the door structure in parallel relation to the plane of the access opening, when the door assembly is opened. This is in contrast to a microwave oven of the type having a hingedly supported door which, since a support table for the support of the food item to be heated is fixedly positioned within the heating chamber, requires the user to bend or stoop to reach the food on the support table within the heating chamber when such oven is used as a base-board model, that is, when it is installed on a kitchen floor below waist level.
When a microwave oven is provided with an electric heating unit for broiling and/or baking inside the oven-defining structure, to provide an electric heating 5~5 capability in addition to the microwave heating capability, a base-board model having a drawer type door assembly has another advantage in that, since the food placed directly on the support base structure or on the rack above the support base structure can be moved out of the heating chamber as the door assembly is drawn out to open the access opening leading into the heating chamber, there is no possibility of the user being burnt in the hand, which can occur if the user inserts his hand into the heating chamber, as is often experienced with microwave ovens of the type having the hingedly supported door.
However, a microwave oven of the base-board type has its own pecul~ar problems to be solved.
; In the first place, complicated measures have to be taken to avoid any possible leakage of microwaves that may take place through a gap between the drawer type door assembly and the oven-defining structure. In the case of a microwave oven of the type having the hingedly supported door, the position of the hingedly supported door relative to the access opening leading into the heating chamber within the oven defining structure is such that, since the door is hinged to one of the edges defining the access opening, there is no substantial possibility of considerable mis-alignment and the door can ~e accommodated within 1 to
A recent development of microwave oven is a type adapted to be installed on a floor, for example, a kitchen floor, which may be referred to as a base-board model.
Of the various base-board models now commercially available, one having a drawer type door assembly of substantially L-shaped construction including a horizontally extending support base structure and a vertically extending door structure is considered convenient and easy to handle, since both the door structure and the support base structure (with or without a rack for the support of a material, for example, a food item, to be heated ) can be simultaneously moved out of the oven-defining structure with the door structure in parallel relation to the plane of the access opening, when the door assembly is opened. This is in contrast to a microwave oven of the type having a hingedly supported door which, since a support table for the support of the food item to be heated is fixedly positioned within the heating chamber, requires the user to bend or stoop to reach the food on the support table within the heating chamber when such oven is used as a base-board model, that is, when it is installed on a kitchen floor below waist level.
When a microwave oven is provided with an electric heating unit for broiling and/or baking inside the oven-defining structure, to provide an electric heating 5~5 capability in addition to the microwave heating capability, a base-board model having a drawer type door assembly has another advantage in that, since the food placed directly on the support base structure or on the rack above the support base structure can be moved out of the heating chamber as the door assembly is drawn out to open the access opening leading into the heating chamber, there is no possibility of the user being burnt in the hand, which can occur if the user inserts his hand into the heating chamber, as is often experienced with microwave ovens of the type having the hingedly supported door.
However, a microwave oven of the base-board type has its own pecul~ar problems to be solved.
; In the first place, complicated measures have to be taken to avoid any possible leakage of microwaves that may take place through a gap between the drawer type door assembly and the oven-defining structure. In the case of a microwave oven of the type having the hingedly supported door, the position of the hingedly supported door relative to the access opening leading into the heating chamber within the oven defining structure is such that, since the door is hinged to one of the edges defining the access opening, there is no substantial possibility of considerable mis-alignment and the door can ~e accommodated within 1 to
2 mm. in height in the horizontal direction. On the contrary, in the case of a microwave oven having a drawer type door assembly, because of the relationship of guide elements oarried by the oven-defining structure to the rail mem~ers carried by the door assembly, displacement in position of the door assembly relative to the access open-ing tends to occur in a range of 2 to 4 mm. Therefore a QS
microwave oven of the type having a drawer type door assembly involves a relatively greater possibility of microwave leakage, as compared with ovens of the type having a hinged door.
In the second place, even though a microwave oven of the type having a drawer type door is generally con-sidered convenient and easy to handle, it involves some problems of oven efficiency, namely a-possibility of metal-to-metal sparking, and problems of heat distribution during microwave heating, unless the manner of placing the material to be heated is carefully determined and unless the selection of a supporting method and material for the oven-defining structure is carefully carried out.
In view of the peculiar problems described above, conventional microwave ovens of base-board type, such as disclosed in U.S. Patents Nos. 2,778,911, 2,782,292 and 4,013,861, respectively patented on January 22, 1957, February 19, 1957 and March 22, 1977, still have the following disadvantages.
U.S. Patent No. 2,778,911 discloses a microwave oven of a type having a drawer type door assembly and, so far as measures for microwave leakage prevention are con-cerned, a metal plate carried by the door assembly is adapted to be pressure-fitted to a metal lining surrounding the perimeter of the access opening leading into the heating chamber when the door assembly is closed, thereby achieving microwave leakage prevention. Although the microwave leakage prevention in the microwave oven of U.S. Patent No. 2,778,911 is satisfactory as far as the initial stage of use thereof is involved, there is a possibility of occur-rence of spark discharge between the plane of the access ~5 opening and the metal plate carried by the door assembly.Moreover, as the microwave oven is used for a substantially prolonged period of time, pile-up of smears and jamming of foreign matter tend to result in deformaton of the metal plate to such an extent that microwaves may leak to the outside of the heating chamber.
U.S. Patent ~o. 2,77~,911 further discloses the use of a tray for the support of the material to be heated, this tray having one end removably supported by the door assembly and the other end having rollers carried by the tray below the latter and resting on the base of the oven-defining structure. The tray can be moved out of the heating chamber within the oven-defining structure, as the door assembly is pulled to open the access opening. In such an arrangement, if the tray is made of a metallic material, the rollers can be fitted to the tray. However, the use of a metallic tray will, since the microwaves tend to be shielded by the metallic tray, result in uneven distribution of microwave enerqy within the heating chamber.
U.S. Patent No. 2,782,292 discloses a microwave oven of a type having a drawer type door assembly wherein a mesh-type food supporting rack is moved together with the door assembly. However, it has been found that, because of the employment of the mesh-type food supporting rac~, the distribution of microwave enerqy tends to be adversely affected and, in addition, there is the possibility that a liquid medium, which may boil over from a container on the food supporting rack, may deposit on the base of the oven-defining structure.
In order to avoid the problem associated with micro-wave lea~age in the oven disclosed in any one of the fore-going U.S r patents, one can readily conceive the employment 11115~S
of a choke structure as disclosed in U.S. Patent No.
4,013,8~1 in the microwave oven of either cf the other foregoing U.S. patents. However, in order to render the choke structure of U.S. Patent No. 4,013,861 employable in the oven of either of U.S. Patents Nos. 2,778,911 and 2,782,292, the following problem has to be solved which is mainly associated with the microwave leakage which may take place through a hook structure secured to the door assembly for the support of a food supporting rack.
As is well known to those skilled in the art, in the case of the microwave oven so constructed as to allow the user to look into the heating chamber from the outside thereof, what divides a free space and the heating chamber in which microwave energy is distributed is a single metallic plate. Accordingly, in order to make it possible for a hook structure, which is often employed in an electric heating oven or in a microwave oven having a door assembly composed of two or more metallic plates and through which the user cannot look into the heating chamber, to be employed and secured to the metallic plate facing the heating chamber so as to extend therethrough, it is necessary to take leakage prevention measures with respect to the holes through which the hook structure extends.
In view of the above, a microwave oven of the base-board ~ype hav~ng a drawer type door assembly and being free from one or other of the foregoing disadvantages and inconveniences, has long ~een sought.
Accordingly, an essential ob~ect of the present invention is to provide a microwave oven of the type having a drawer type door assembly wherein any possibility of significant leakage of microwave energy through the perimeter of the door, particularly through a gap between the periphery of the door assembly and the surrounding edge of the access opening leading into the heating chamber, is eliminated.
To this end the invention provides in a microwave oven comprising an oven-defining structure having an access opening leading into a heating chamber defined therein, a drawer type door assembly including a door structure adapted to close and open the access opening, and a rail structure movably supported to facilitate movement of the door structure between closed and opened positions, a microwave power source for transmitting microwave energy into the heating chamber, and hook members each having a plurality of hooks for the support of a rack adapted to support a material to be heated, the improvement wherein said door assembly is provided with a capacitance coupling and a choke cavity for shielding when the door structure is in the closed position and microwave energy is radiated into the heating chamber, said door structure during movement thereof between closed and opened positions moving in sub-2~ stantially parallel relation to the plane of the accessopening.
Another object of a preferred embodiment of the present invention is to provide the microwave oven of the type referred to above, wherein a removable metallic mesh rack for the support of a container accommodating therein a material to be heated is so constructed as to avoid the possibility of an electric spark discharge, with correspond-ing increased heating efficiency.
These and other features of embodiments of the ~resent invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a side sectional view of a microwave oven according to one embodiment of the present invention;
Fig. 2 is a side sectional view of a drawer type door assembly;
Figs. 3, 4 and 5 are side sectional views of a portion of the drawer type door assembly, showing respective embodiments of the present invention;
Fig. 6 is a plan view of a portion of a door fixture;
Fig. 7 is a top sectional view, on an enlarged scale, of a portion of the drawer type door assembly;
Fig. 8 is a side sectional view of a microwave oven according to a further embodiment of the present invention;
Figs. 9(a) and 9(b) are a top plan view and a side sectional view of a tray for the support of a food supporting grill, respectively;
Fig. 10 is a side sectional view , on an enlarged scale, of an essential portion shown in Fig. 9(b); and Fig. 11 is a side sectional view of a hingedly supported door employed in a conventional microwave oven.
Referring first to Fig. 1, a microwave oven of the type having a drawer type door assembly comprises a micro-wave energy source, for example, a magnetron 2, capable of emitting microwaves when energized. m e microwaves from the magnetron 2 are fed through a waveguide 3 to an antenna 4, a portion of such antenna 4 protruding into a heating chamber 1 through an opening 5 defined in the waveguide 3 so that the microwaves can be radiated into the heating chamber 1. The opening 5 in the waveguide 3 through which the antenna 4 protrudes is closed by a cover 6~ made of dielectric material.
~tll~S
For the purpose of providing an electric heating capability in addition to the microwave heating capability, the oven further comprises an electric heater 7 extending into the heating chamber adjacent the top thereof and coupled to an electric power supply socket 8. The electric heater 7 is supported in position by holders 9. In addition to the heater 7, an additional heater 10 is positioned externally of the heating chamber 1 beneath the bottom thereof, the heater 10 being coupled to an electric power supply socket 11 and covered by a heater cover 12.
The drawer type door assembly comprises a door structure 13 including a glass plate 14, the periphery of which is held against a door framework through a gasket 15 to avoid leakage of hot air from the heating cha~ber 1.
A handle 16 is accessible to the user and a door rail structure 19 extends substantially at right angles to the door structure 13 while carrying a plurality of rollers 18.
The door assembly is supported for movement between closed and open positions by the rollers 18 and a plurality of rollers 17 which are rotatably supported on the base of a housing structure. The door rail structure 19 is rigidly connected at one end thereof to the bottom of the door structure 13 by means of a bracket 54 , the other end of the rail structure 19 being provided with a spring stopper 20 which is made of an elastic metallic material and which holds the door as~sembly in its closed position when the latter is moved thereto.
The door structure 13 further includes a door 21 having a plurality of slits 22, a plurality of reinforcing ribs 23 and at least one pair of hook members each hauing a plurality of hooks 24 secured to the door by means of _ ~ _ 11115~S
hexagonal bolts 25.
me oven further comprises a circulating fan 27 driven by a motor 28 housed within a casing 29, this fan 27 being separated from the heating chamber 1 by a per-forated partition wall 57. It is to be noted that, since the partition wall 57 is perforated, the air current produced by the fan 27 can flow into the heating chamber 1. The fan 27 is positioned behind the wall 57 and is housed within a chamber defined by such wall 57 and a covering 30 externally surrounding the perimeter of the fan 27.
Positioned above the door structure 13 is a control panel having a temperature control knob 31 coupled to a control box 32 which is in turn coupled through a connecting rod 33 to a temperature control switch 34 operatively associated with a temperature sensor 35.
Positioned adjacent the magnetron 2 is a fan 36 for cooling the magnetron 2 during operation. There is also a ventilator fan 37 positioned externally of and adjacent an upper rear corner of the heating chamber 1.
For illuminating the heating chamber 1 there is an electric lamp 38, the light from which is transmitted to-wards the heating chamber 1 through an illuminating window 39 formed in the top wall of the oven-defining structure and which is covered by a glass plate 40 for preventing spatters from reaching the lamp 38.
The antenna 4 is coupled to a drive shaft 47 of a motor 4B through a connecting shaft 41 made of dielectric material, this connecting shaft 41 extending rotatably through a dielectric plate member 42 which also serves as a bearing plate. The motor shaft 47 and the connecting ~111~5 shaft 41 extend through a space defined by a covering 43 and, within such space, there is a sliding cone 44 mounted in part on the motor shaft 47 and in part on the connecting shaft 41 and secured thereto by means of respective pins 46 and 45.
Reference numeral 49 represents a microswitch which is closed only when the door assembly is held in the closed position. Reference numeral 50 represents body reinforce-ment beams and reference numeral 51 represents body rein-forcement ribs. The magnetron 2 and the cooling fan 36 arehoused within a casing 52 positioned below the oven-defining structure having the heating chamber 1 therein.
Reference numerals 53 and 55 represent retaining covers for retaining in position respective layers of heat insulating material (not shown). Reference numeral 56 represents the housing structure of the oven.
Referring now to Fig. 2, the door structure 13 includes a pair of glass plates 14a and 14b and a perforated plate 57 held against the glass plate 14b, the glass plates 14a and 14b being supported in spaced relation to each other by a door 59. The door 21 is used to secure the glass plate 14b and the perforated plate 57 to the door 59. The door 21 has a flange 60 bent at right angles relative to the body of the door 21 and extending towards the door 59, which flange 60 defines a cho~e cavity 61 in cooperation with the door 59. Reference n~meral 58 represents a front overhang plate contiguous to a front extension 62 protruding forwardly rrom the heating chamber 1. The front extension 58 cooperates with the flange 60 to define a capacitance coupling between the front extension 58 and the flange 60 when the door assembly is held in the closed position.
111~3~5 In Fig. 2, the door assembly is shown with the door 21 of the door structure 13 accommodated within the heating chamber 1. Since the movement of the door assembly between the closed and opened positions takes place in a direction parallel to the direction of protrusion of the front extension 62 of the heating chamber l, the period of time during which the distance shown by Qq can be main-tained at a constant value can be prolonged by varying the distance shown by Qp. Accordingly, since the distance QP can be chosed to have a relatively small value at an upper edge portion of the door assembly, as compared with the case of a microwave oven having a hingedly supported door assembly, the capacitance coupling effect is relatively high with a minimized amount of microwave leakage, thereby obviating the need to employ a microwave absorbing element, such as ferrite, which has heretofore been required.
Furthermore, even though thermal deformation takes place due to heating by the electric heaters over a prolonged period of use, the improved microwave leakage prevention can still be attained, compared with a microwave oven wherein the door, when closed, faces an access opening leading into the heating chamber in a face-to-face relation. In relation to the problem that a drawer type door assembly is susceptible to displacement horizontally relative to the access opening, as compared with the case of a hingedly supported door, this can readily be solved by providing a suitable rounding at a corner portion of the access opening and/or the door 21 without enlarging the distance ~q and without making it possible that the door 21 not enter the heating chamber l as the door assembly is closed.
111~5Q5 Moreover, when the door assembly is to be closed, the distance Qq can be maintained at a substantially zero value by the application of force to the rail structure 19 in the direction indicated by the arrow in Fig. 2 and, therefore, there is no possibility of leakage of microwave energy to the outside of the heating chamber, even if the amount of microwave energy leaking from the choke cavity is high.
With this construction, since the microwave leakage preventive performance is high, it is possible to make available a relatively large clearance for disposition of the switch 49 which is employed to detect the position of the door assembly and which is closed only when the door assembly is closed.
Fig. 3 illustrates an example wherein the flange 60 of the door 21 is operatively associated with a metallic panel 63, sLmilar in construction to a picture frame, protruding ~orwardly of the access opening perpendicularly to the plane of the access opening.
Fig. 4 illustrates another example wherein an opening leading into the choke cavity 61 is operatively associated with a front planar plate of the heating chamber.
Fig. 5 illustrates a further example wherein a projection having a length shown by Qs is formed in the door structure 13 shown in Fig. 2.
When the door structure 13 is constructed in a manner shown in one of Figs. 3 to 5, a substantially similar microwave leakage preventive per~ormance as that afforded by the door structure shown in Fig. 2 is achieved.
Fig. 6 illustrates details of slits 22 in the flange of the door 21 for improving the microwave leakage prevention.
~ 12 -The reason why a distance corresponding to the distance Qq cannot be minimized in a microwave oven of the type having a hingedly supported door assembly will now be described with reference to Fig. 11.
Referring to Fig. 11, assuming that the door assembly 102 has a thickness T and is pivoted about a hinge pin 101 during opening and closing of the access opening, the distance Q must be greater than the distance ~o. To achieve this relationship the clearance between the perimeter 103 of the door assembly and the oven-defining structure 104 must be greater than the difference between the distances Q and ~o. Therefore, such clearance cannot be less than a certain value. In view of this, the hingedly supported door assembly has to be provided with a microwave absorbing element, such as the ferrite block 105.
Referring now to Fig. 7, there is here illustrated the detailed manner of support of the hook members 24 for support of the food support rack, as will be described later, only one of the hook members 24 being shown in Fig. 7.
In Fig. 7, reference numerals 61, 65 and 66 respectively represent a choke cavity and two doors. Numerals 67, 68 and 69 represent glass plates and numeral 70 represents a heat insulating spacer. Numerals 71 and 72 represent gaskets while numerals 73 and 74 represent glass retainers secured to the doors by means of screw members 75. Numeral 76 re-presents bolts used to connect the door structure and the rail structure.
Numeral 77 represents a retainer for retaining a heat insulating layer in the door structure and numeral 78 ~pr~sn~9 a flange of the heating chamber. Numeral 79 represents one of the opposed side walls surrounding the QS
heating chamber and numeral 80 represents a portion of a sash.
One of the features of the present construction resides in that the hook members 24 are positioned to face towards the heating chamber.
In a construction wherein the user can look into the heating chamber through a perforated plate, as in the present construction, if a portion of one of the hook members 24 projects to the outside through the door 65 or through the door 66, that portion of the hook member 24 that projects outside could serve as an antenna raising the possibility that microwave energy might leak to the outside of the heating chamber. However, this possibility can be eliminated by employing the construction shown in Fig. 7.
Referring to Fig. 8, there is here shown an example wherein a rack 86 with a tray 85 thereon is accommodated within the heating chamber 1. In the construction shown in Fig. 8, the wavegui~de 3 for transmitting energy from the magnetron 2 opens at a rear wall 82 of the oven-defining structure 81 through a radiating opening 5 in such rear wall 82. The rear wall 82 is opposed to the access opening lead-ing into the heating cham~er 1 and is adapted to ~e closed and opened by the door assembly, particularly the door structure 13. Projecting into the waveguide 3 from the magnetron 2 is a magnetron antenna 83.
One surface of the door structure 13 facing towards - the heating chamber 1 is provided with hook members 24 on which is hung a rack 86 in the form of a metallic mesh for support of the tray 85 on which the food item 84 is placed.
The rack 86 is designed to support the perimeter of the tray 85 when the latter is placed on the rack 86, as best shown in Figs. 9(a) and 9(b). In other words, the rack 86 is so designed as to have horizontally extending portions a, b, c and d on which the peripheral portions of the tray 85 rest with no possibility of the tray 85 falling below the rack 86 and no possibility of the tray 85 being displaced out of alignment with the rack 86.
The tray 85 is preferably made of a dielectric material, such as porcelain or glass, to permit the microwave energy to permeate therethrough.
It is to be noted that, to reinforce the rack 86 so that the latter can support the total weight of the B tray ~ and the food item, the rack 86 may have transverse and/or longitudinal reinforcing rods unless the disposition of these reinforcing rods adversely affects the pattern of distribution of heat within the heating chamber.
The rack 86 is preferably made by bending wire elements, the opposed ends of such elements being welded to each other, so that the resultant rack 86 can be readily handled without injury to the hands of the user which could occur if there were fins or knife edges on the wire element forming the rack. Moreover, the rack 86 does not involve the possibility of being heated during the microwave operation.
Therefore there is no possibility that the user of the oven may burn his hand when touching the rack 86.
Furthermore, the hook members 24 and the rack 86 are preferably made of an anti-ferromagnetic material, such as stainless steel, to minimize the possibility of becoming heated during the microwave heating. This is because an anti-ferromagnetic material does not conduct induction currents in the presence of microwave energy and, therefore, S
will not be heated.
If the rack-to-rack distance or the space between the perimeter of the rack and the walls of the structure forming the heating chamber is selected to be one tenth or more of the wavelength of the microwaves employed, for example, not less than 12 mm. in the case of microwaves of a wavelength of 120 mm., the rack 86 will not shield the passage of microwave energy therethrough and, therefore, the oven chamber can accommodate two or more racks simultaneously.
Removal of the rack 86 from the associated hooks of the members 24 can be carried out by moving the rack 86 in the direction indicated by the arrow in Fig. 9(b).
When and so long as the rack 86 is hung on the as-sociated hooks of the hook members 24, two metallic rods forming the rack 86 are engaged with the hook members 24 in a manner such as shown in Fig. 10. Numeral 88 represents an insulating coating , such as an enamel coating applied to any one of the hook members 24 for avoiding the pos-sibility of heating portions of the hook members 24 that the rack 86 contacts and also the occurrence of a spark discharge between one of the hook members 24 and the rack 86.
It is to be noted that, instead of applying the insulating coating to the hook members 24, it may be applied to the rack 86, or it may be applied to both the rack and the hook members 24.
While the rack 86 and the hook members 24 are con-structed and positioned in the manner described above, employment of the tray 85 of dielectric material does not provide any obstruction to uniform development of an electro-magnetic field within the heating chamber, and a portion ofthe microwave energy reflected from the base of the oven-defining structure can be utilized for~heating the food ~15Q5 item on the tray 85 from the bottom thereof.
In addition, since the food item 84 to be heated is placed on the tray 85 which is in turn mounted on the rack 86 during heating, not only can the food item be supported steadily in position, but also there is lhttle possibility of any spatter or any other liquid medium that may boil over from the food item being heated, falling onto the bottom of the heating chamber. Therefore, there is minimum risk of the bottom of the heating chamber becoming soiled 1~ by spatters and/or smears.
The oven according to the present invention can be used concurrently as a microwave oven wherein heating is solely dependent on the application of microwave energy and as an electrlc oven wherein the heating is from heaters.
microwave oven of the type having a drawer type door assembly involves a relatively greater possibility of microwave leakage, as compared with ovens of the type having a hinged door.
In the second place, even though a microwave oven of the type having a drawer type door is generally con-sidered convenient and easy to handle, it involves some problems of oven efficiency, namely a-possibility of metal-to-metal sparking, and problems of heat distribution during microwave heating, unless the manner of placing the material to be heated is carefully determined and unless the selection of a supporting method and material for the oven-defining structure is carefully carried out.
In view of the peculiar problems described above, conventional microwave ovens of base-board type, such as disclosed in U.S. Patents Nos. 2,778,911, 2,782,292 and 4,013,861, respectively patented on January 22, 1957, February 19, 1957 and March 22, 1977, still have the following disadvantages.
U.S. Patent No. 2,778,911 discloses a microwave oven of a type having a drawer type door assembly and, so far as measures for microwave leakage prevention are con-cerned, a metal plate carried by the door assembly is adapted to be pressure-fitted to a metal lining surrounding the perimeter of the access opening leading into the heating chamber when the door assembly is closed, thereby achieving microwave leakage prevention. Although the microwave leakage prevention in the microwave oven of U.S. Patent No. 2,778,911 is satisfactory as far as the initial stage of use thereof is involved, there is a possibility of occur-rence of spark discharge between the plane of the access ~5 opening and the metal plate carried by the door assembly.Moreover, as the microwave oven is used for a substantially prolonged period of time, pile-up of smears and jamming of foreign matter tend to result in deformaton of the metal plate to such an extent that microwaves may leak to the outside of the heating chamber.
U.S. Patent ~o. 2,77~,911 further discloses the use of a tray for the support of the material to be heated, this tray having one end removably supported by the door assembly and the other end having rollers carried by the tray below the latter and resting on the base of the oven-defining structure. The tray can be moved out of the heating chamber within the oven-defining structure, as the door assembly is pulled to open the access opening. In such an arrangement, if the tray is made of a metallic material, the rollers can be fitted to the tray. However, the use of a metallic tray will, since the microwaves tend to be shielded by the metallic tray, result in uneven distribution of microwave enerqy within the heating chamber.
U.S. Patent No. 2,782,292 discloses a microwave oven of a type having a drawer type door assembly wherein a mesh-type food supporting rack is moved together with the door assembly. However, it has been found that, because of the employment of the mesh-type food supporting rac~, the distribution of microwave enerqy tends to be adversely affected and, in addition, there is the possibility that a liquid medium, which may boil over from a container on the food supporting rack, may deposit on the base of the oven-defining structure.
In order to avoid the problem associated with micro-wave lea~age in the oven disclosed in any one of the fore-going U.S r patents, one can readily conceive the employment 11115~S
of a choke structure as disclosed in U.S. Patent No.
4,013,8~1 in the microwave oven of either cf the other foregoing U.S. patents. However, in order to render the choke structure of U.S. Patent No. 4,013,861 employable in the oven of either of U.S. Patents Nos. 2,778,911 and 2,782,292, the following problem has to be solved which is mainly associated with the microwave leakage which may take place through a hook structure secured to the door assembly for the support of a food supporting rack.
As is well known to those skilled in the art, in the case of the microwave oven so constructed as to allow the user to look into the heating chamber from the outside thereof, what divides a free space and the heating chamber in which microwave energy is distributed is a single metallic plate. Accordingly, in order to make it possible for a hook structure, which is often employed in an electric heating oven or in a microwave oven having a door assembly composed of two or more metallic plates and through which the user cannot look into the heating chamber, to be employed and secured to the metallic plate facing the heating chamber so as to extend therethrough, it is necessary to take leakage prevention measures with respect to the holes through which the hook structure extends.
In view of the above, a microwave oven of the base-board ~ype hav~ng a drawer type door assembly and being free from one or other of the foregoing disadvantages and inconveniences, has long ~een sought.
Accordingly, an essential ob~ect of the present invention is to provide a microwave oven of the type having a drawer type door assembly wherein any possibility of significant leakage of microwave energy through the perimeter of the door, particularly through a gap between the periphery of the door assembly and the surrounding edge of the access opening leading into the heating chamber, is eliminated.
To this end the invention provides in a microwave oven comprising an oven-defining structure having an access opening leading into a heating chamber defined therein, a drawer type door assembly including a door structure adapted to close and open the access opening, and a rail structure movably supported to facilitate movement of the door structure between closed and opened positions, a microwave power source for transmitting microwave energy into the heating chamber, and hook members each having a plurality of hooks for the support of a rack adapted to support a material to be heated, the improvement wherein said door assembly is provided with a capacitance coupling and a choke cavity for shielding when the door structure is in the closed position and microwave energy is radiated into the heating chamber, said door structure during movement thereof between closed and opened positions moving in sub-2~ stantially parallel relation to the plane of the accessopening.
Another object of a preferred embodiment of the present invention is to provide the microwave oven of the type referred to above, wherein a removable metallic mesh rack for the support of a container accommodating therein a material to be heated is so constructed as to avoid the possibility of an electric spark discharge, with correspond-ing increased heating efficiency.
These and other features of embodiments of the ~resent invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a side sectional view of a microwave oven according to one embodiment of the present invention;
Fig. 2 is a side sectional view of a drawer type door assembly;
Figs. 3, 4 and 5 are side sectional views of a portion of the drawer type door assembly, showing respective embodiments of the present invention;
Fig. 6 is a plan view of a portion of a door fixture;
Fig. 7 is a top sectional view, on an enlarged scale, of a portion of the drawer type door assembly;
Fig. 8 is a side sectional view of a microwave oven according to a further embodiment of the present invention;
Figs. 9(a) and 9(b) are a top plan view and a side sectional view of a tray for the support of a food supporting grill, respectively;
Fig. 10 is a side sectional view , on an enlarged scale, of an essential portion shown in Fig. 9(b); and Fig. 11 is a side sectional view of a hingedly supported door employed in a conventional microwave oven.
Referring first to Fig. 1, a microwave oven of the type having a drawer type door assembly comprises a micro-wave energy source, for example, a magnetron 2, capable of emitting microwaves when energized. m e microwaves from the magnetron 2 are fed through a waveguide 3 to an antenna 4, a portion of such antenna 4 protruding into a heating chamber 1 through an opening 5 defined in the waveguide 3 so that the microwaves can be radiated into the heating chamber 1. The opening 5 in the waveguide 3 through which the antenna 4 protrudes is closed by a cover 6~ made of dielectric material.
~tll~S
For the purpose of providing an electric heating capability in addition to the microwave heating capability, the oven further comprises an electric heater 7 extending into the heating chamber adjacent the top thereof and coupled to an electric power supply socket 8. The electric heater 7 is supported in position by holders 9. In addition to the heater 7, an additional heater 10 is positioned externally of the heating chamber 1 beneath the bottom thereof, the heater 10 being coupled to an electric power supply socket 11 and covered by a heater cover 12.
The drawer type door assembly comprises a door structure 13 including a glass plate 14, the periphery of which is held against a door framework through a gasket 15 to avoid leakage of hot air from the heating cha~ber 1.
A handle 16 is accessible to the user and a door rail structure 19 extends substantially at right angles to the door structure 13 while carrying a plurality of rollers 18.
The door assembly is supported for movement between closed and open positions by the rollers 18 and a plurality of rollers 17 which are rotatably supported on the base of a housing structure. The door rail structure 19 is rigidly connected at one end thereof to the bottom of the door structure 13 by means of a bracket 54 , the other end of the rail structure 19 being provided with a spring stopper 20 which is made of an elastic metallic material and which holds the door as~sembly in its closed position when the latter is moved thereto.
The door structure 13 further includes a door 21 having a plurality of slits 22, a plurality of reinforcing ribs 23 and at least one pair of hook members each hauing a plurality of hooks 24 secured to the door by means of _ ~ _ 11115~S
hexagonal bolts 25.
me oven further comprises a circulating fan 27 driven by a motor 28 housed within a casing 29, this fan 27 being separated from the heating chamber 1 by a per-forated partition wall 57. It is to be noted that, since the partition wall 57 is perforated, the air current produced by the fan 27 can flow into the heating chamber 1. The fan 27 is positioned behind the wall 57 and is housed within a chamber defined by such wall 57 and a covering 30 externally surrounding the perimeter of the fan 27.
Positioned above the door structure 13 is a control panel having a temperature control knob 31 coupled to a control box 32 which is in turn coupled through a connecting rod 33 to a temperature control switch 34 operatively associated with a temperature sensor 35.
Positioned adjacent the magnetron 2 is a fan 36 for cooling the magnetron 2 during operation. There is also a ventilator fan 37 positioned externally of and adjacent an upper rear corner of the heating chamber 1.
For illuminating the heating chamber 1 there is an electric lamp 38, the light from which is transmitted to-wards the heating chamber 1 through an illuminating window 39 formed in the top wall of the oven-defining structure and which is covered by a glass plate 40 for preventing spatters from reaching the lamp 38.
The antenna 4 is coupled to a drive shaft 47 of a motor 4B through a connecting shaft 41 made of dielectric material, this connecting shaft 41 extending rotatably through a dielectric plate member 42 which also serves as a bearing plate. The motor shaft 47 and the connecting ~111~5 shaft 41 extend through a space defined by a covering 43 and, within such space, there is a sliding cone 44 mounted in part on the motor shaft 47 and in part on the connecting shaft 41 and secured thereto by means of respective pins 46 and 45.
Reference numeral 49 represents a microswitch which is closed only when the door assembly is held in the closed position. Reference numeral 50 represents body reinforce-ment beams and reference numeral 51 represents body rein-forcement ribs. The magnetron 2 and the cooling fan 36 arehoused within a casing 52 positioned below the oven-defining structure having the heating chamber 1 therein.
Reference numerals 53 and 55 represent retaining covers for retaining in position respective layers of heat insulating material (not shown). Reference numeral 56 represents the housing structure of the oven.
Referring now to Fig. 2, the door structure 13 includes a pair of glass plates 14a and 14b and a perforated plate 57 held against the glass plate 14b, the glass plates 14a and 14b being supported in spaced relation to each other by a door 59. The door 21 is used to secure the glass plate 14b and the perforated plate 57 to the door 59. The door 21 has a flange 60 bent at right angles relative to the body of the door 21 and extending towards the door 59, which flange 60 defines a cho~e cavity 61 in cooperation with the door 59. Reference n~meral 58 represents a front overhang plate contiguous to a front extension 62 protruding forwardly rrom the heating chamber 1. The front extension 58 cooperates with the flange 60 to define a capacitance coupling between the front extension 58 and the flange 60 when the door assembly is held in the closed position.
111~3~5 In Fig. 2, the door assembly is shown with the door 21 of the door structure 13 accommodated within the heating chamber 1. Since the movement of the door assembly between the closed and opened positions takes place in a direction parallel to the direction of protrusion of the front extension 62 of the heating chamber l, the period of time during which the distance shown by Qq can be main-tained at a constant value can be prolonged by varying the distance shown by Qp. Accordingly, since the distance QP can be chosed to have a relatively small value at an upper edge portion of the door assembly, as compared with the case of a microwave oven having a hingedly supported door assembly, the capacitance coupling effect is relatively high with a minimized amount of microwave leakage, thereby obviating the need to employ a microwave absorbing element, such as ferrite, which has heretofore been required.
Furthermore, even though thermal deformation takes place due to heating by the electric heaters over a prolonged period of use, the improved microwave leakage prevention can still be attained, compared with a microwave oven wherein the door, when closed, faces an access opening leading into the heating chamber in a face-to-face relation. In relation to the problem that a drawer type door assembly is susceptible to displacement horizontally relative to the access opening, as compared with the case of a hingedly supported door, this can readily be solved by providing a suitable rounding at a corner portion of the access opening and/or the door 21 without enlarging the distance ~q and without making it possible that the door 21 not enter the heating chamber l as the door assembly is closed.
111~5Q5 Moreover, when the door assembly is to be closed, the distance Qq can be maintained at a substantially zero value by the application of force to the rail structure 19 in the direction indicated by the arrow in Fig. 2 and, therefore, there is no possibility of leakage of microwave energy to the outside of the heating chamber, even if the amount of microwave energy leaking from the choke cavity is high.
With this construction, since the microwave leakage preventive performance is high, it is possible to make available a relatively large clearance for disposition of the switch 49 which is employed to detect the position of the door assembly and which is closed only when the door assembly is closed.
Fig. 3 illustrates an example wherein the flange 60 of the door 21 is operatively associated with a metallic panel 63, sLmilar in construction to a picture frame, protruding ~orwardly of the access opening perpendicularly to the plane of the access opening.
Fig. 4 illustrates another example wherein an opening leading into the choke cavity 61 is operatively associated with a front planar plate of the heating chamber.
Fig. 5 illustrates a further example wherein a projection having a length shown by Qs is formed in the door structure 13 shown in Fig. 2.
When the door structure 13 is constructed in a manner shown in one of Figs. 3 to 5, a substantially similar microwave leakage preventive per~ormance as that afforded by the door structure shown in Fig. 2 is achieved.
Fig. 6 illustrates details of slits 22 in the flange of the door 21 for improving the microwave leakage prevention.
~ 12 -The reason why a distance corresponding to the distance Qq cannot be minimized in a microwave oven of the type having a hingedly supported door assembly will now be described with reference to Fig. 11.
Referring to Fig. 11, assuming that the door assembly 102 has a thickness T and is pivoted about a hinge pin 101 during opening and closing of the access opening, the distance Q must be greater than the distance ~o. To achieve this relationship the clearance between the perimeter 103 of the door assembly and the oven-defining structure 104 must be greater than the difference between the distances Q and ~o. Therefore, such clearance cannot be less than a certain value. In view of this, the hingedly supported door assembly has to be provided with a microwave absorbing element, such as the ferrite block 105.
Referring now to Fig. 7, there is here illustrated the detailed manner of support of the hook members 24 for support of the food support rack, as will be described later, only one of the hook members 24 being shown in Fig. 7.
In Fig. 7, reference numerals 61, 65 and 66 respectively represent a choke cavity and two doors. Numerals 67, 68 and 69 represent glass plates and numeral 70 represents a heat insulating spacer. Numerals 71 and 72 represent gaskets while numerals 73 and 74 represent glass retainers secured to the doors by means of screw members 75. Numeral 76 re-presents bolts used to connect the door structure and the rail structure.
Numeral 77 represents a retainer for retaining a heat insulating layer in the door structure and numeral 78 ~pr~sn~9 a flange of the heating chamber. Numeral 79 represents one of the opposed side walls surrounding the QS
heating chamber and numeral 80 represents a portion of a sash.
One of the features of the present construction resides in that the hook members 24 are positioned to face towards the heating chamber.
In a construction wherein the user can look into the heating chamber through a perforated plate, as in the present construction, if a portion of one of the hook members 24 projects to the outside through the door 65 or through the door 66, that portion of the hook member 24 that projects outside could serve as an antenna raising the possibility that microwave energy might leak to the outside of the heating chamber. However, this possibility can be eliminated by employing the construction shown in Fig. 7.
Referring to Fig. 8, there is here shown an example wherein a rack 86 with a tray 85 thereon is accommodated within the heating chamber 1. In the construction shown in Fig. 8, the wavegui~de 3 for transmitting energy from the magnetron 2 opens at a rear wall 82 of the oven-defining structure 81 through a radiating opening 5 in such rear wall 82. The rear wall 82 is opposed to the access opening lead-ing into the heating cham~er 1 and is adapted to ~e closed and opened by the door assembly, particularly the door structure 13. Projecting into the waveguide 3 from the magnetron 2 is a magnetron antenna 83.
One surface of the door structure 13 facing towards - the heating chamber 1 is provided with hook members 24 on which is hung a rack 86 in the form of a metallic mesh for support of the tray 85 on which the food item 84 is placed.
The rack 86 is designed to support the perimeter of the tray 85 when the latter is placed on the rack 86, as best shown in Figs. 9(a) and 9(b). In other words, the rack 86 is so designed as to have horizontally extending portions a, b, c and d on which the peripheral portions of the tray 85 rest with no possibility of the tray 85 falling below the rack 86 and no possibility of the tray 85 being displaced out of alignment with the rack 86.
The tray 85 is preferably made of a dielectric material, such as porcelain or glass, to permit the microwave energy to permeate therethrough.
It is to be noted that, to reinforce the rack 86 so that the latter can support the total weight of the B tray ~ and the food item, the rack 86 may have transverse and/or longitudinal reinforcing rods unless the disposition of these reinforcing rods adversely affects the pattern of distribution of heat within the heating chamber.
The rack 86 is preferably made by bending wire elements, the opposed ends of such elements being welded to each other, so that the resultant rack 86 can be readily handled without injury to the hands of the user which could occur if there were fins or knife edges on the wire element forming the rack. Moreover, the rack 86 does not involve the possibility of being heated during the microwave operation.
Therefore there is no possibility that the user of the oven may burn his hand when touching the rack 86.
Furthermore, the hook members 24 and the rack 86 are preferably made of an anti-ferromagnetic material, such as stainless steel, to minimize the possibility of becoming heated during the microwave heating. This is because an anti-ferromagnetic material does not conduct induction currents in the presence of microwave energy and, therefore, S
will not be heated.
If the rack-to-rack distance or the space between the perimeter of the rack and the walls of the structure forming the heating chamber is selected to be one tenth or more of the wavelength of the microwaves employed, for example, not less than 12 mm. in the case of microwaves of a wavelength of 120 mm., the rack 86 will not shield the passage of microwave energy therethrough and, therefore, the oven chamber can accommodate two or more racks simultaneously.
Removal of the rack 86 from the associated hooks of the members 24 can be carried out by moving the rack 86 in the direction indicated by the arrow in Fig. 9(b).
When and so long as the rack 86 is hung on the as-sociated hooks of the hook members 24, two metallic rods forming the rack 86 are engaged with the hook members 24 in a manner such as shown in Fig. 10. Numeral 88 represents an insulating coating , such as an enamel coating applied to any one of the hook members 24 for avoiding the pos-sibility of heating portions of the hook members 24 that the rack 86 contacts and also the occurrence of a spark discharge between one of the hook members 24 and the rack 86.
It is to be noted that, instead of applying the insulating coating to the hook members 24, it may be applied to the rack 86, or it may be applied to both the rack and the hook members 24.
While the rack 86 and the hook members 24 are con-structed and positioned in the manner described above, employment of the tray 85 of dielectric material does not provide any obstruction to uniform development of an electro-magnetic field within the heating chamber, and a portion ofthe microwave energy reflected from the base of the oven-defining structure can be utilized for~heating the food ~15Q5 item on the tray 85 from the bottom thereof.
In addition, since the food item 84 to be heated is placed on the tray 85 which is in turn mounted on the rack 86 during heating, not only can the food item be supported steadily in position, but also there is lhttle possibility of any spatter or any other liquid medium that may boil over from the food item being heated, falling onto the bottom of the heating chamber. Therefore, there is minimum risk of the bottom of the heating chamber becoming soiled 1~ by spatters and/or smears.
The oven according to the present invention can be used concurrently as a microwave oven wherein heating is solely dependent on the application of microwave energy and as an electrlc oven wherein the heating is from heaters.
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a microwave oven comprising an oven-defining structure having an access opening leading into a heating chamber defined therein, a drawer type door assembly in-cluding a door structure adapted to close and open the access opening, and a rail structure movably supported to facilitate movement of the door structure between closed and opened positions, a microwave power source for trans-mitting microwave energy into the heating chamber, and hook members each having a plurality of hooks for the support of a rack adapted to support a material to be heated, the improvement wherein said door assembly is provided with a capacitance coupling and a choke cavity for shielding when the door structure is in the closed position and micro-wave energy is radiated into the heating chamber, said door structure during movement thereof between closed and opened positions moving in substantially parallel relation to the plane of the access opening.
2. A microwave oven as claimed in Claim 1, wherein said choke cavity in the door assembly is defined in the door structure such that, when said door structure is in closed position, said choke cavity is accommodated within the heating chamber.
3. A microwave oven as claimed in Claim 1, further comprising a metallic panel member provided on the perimeter of the door structure and having a plane perpendicular to the plane of the access opening, said capacitance coupling and said choke cavity being operatively associated with said metallic panel member.
4. A microwave oven as claimed in Claim 1, wherein one of a plurality of planes defining the choke cavity, which faces an opening leading into the choke cavity, is formed with a plurality of slits each extending in parallel relation to a direction of extension of the access opening.
5. A microwave oven as claimed in Claim 1, wherein said hook members are secured to a door member of the door structure facing the heating chamber and positioned inside the heating chamber when the door structure is in closed position.
6. A microwave oven as claimed in Claim 5, further comprising a tray of dielectric material, said tray being removably mounted on a rack, said rack being made of a metallic mesh and adapted to be removably mounted on the hook portions of the hook members, said material to be heated being adapted to be supported on the rack through the tray,
7. A microwave oven as claimed in Claim 6, wherein said rack is made of a metallic wire element shaped into the mesh form, said tray when mounted on the rack having its peripheral edge portion resting on the perimeter of the rack.
8. A microwave oven as claimed in Claim 6, wherein at least one of said rack and said hook members is made of stainless steel.
9. A microwave oven as claimed in Claim 6, wherein at least one of said rack and said hook members is coated with an electric insulating material.
10. A microwave oven as claimed in Claim 6, wherein said rack has a plurality of rod members, each two adjacent such members being spaced from each other a distance sub-stantially equal to or greater than one tenth of the wavelength of the microwaves generated by the microwave power source.
11. A microwave oven as claimed in Claim 6, wherein said rack, when accommodated within the heating chamber, has its perimeter spaced from walls of the heating chamber a distance substantially equal to or greater than one tneth of the wavelength of the microwaves generated by the microwave power source.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP103619/1977 | 1977-08-01 | ||
| JP9275177A JPS5426549A (en) | 1977-08-01 | 1977-08-01 | High frequency wave heating device |
| JP1977103619U JPS5720964Y2 (en) | 1977-08-01 | 1977-08-01 | |
| JP92751/1977 | 1977-08-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1111505A true CA1111505A (en) | 1981-10-27 |
Family
ID=26434128
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA300,742A Expired CA1111505A (en) | 1977-08-01 | 1978-04-10 | Microwave oven having a radiation leak-proof drawer type door |
Country Status (8)
| Country | Link |
|---|---|
| AU (1) | AU521773B2 (en) |
| CA (1) | CA1111505A (en) |
| CH (1) | CH632627A5 (en) |
| DE (1) | DE2833040A1 (en) |
| FR (1) | FR2399780A1 (en) |
| GB (1) | GB2002210B (en) |
| IT (1) | IT1097788B (en) |
| YU (1) | YU41111B (en) |
Families Citing this family (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5948517B2 (en) * | 1979-09-11 | 1984-11-27 | 松下電器産業株式会社 | High frequency heating device |
| JPS6047716B2 (en) * | 1980-10-03 | 1985-10-23 | 松下電器産業株式会社 | High frequency heating device |
| DE3106786A1 (en) * | 1981-02-24 | 1982-09-09 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | Microwave heating apparatus |
| JPS5933792A (en) * | 1982-08-17 | 1984-02-23 | 松下電器産業株式会社 | High frequency heater |
| JPS5933793A (en) * | 1982-08-18 | 1984-02-23 | 松下電器産業株式会社 | High frequency heater |
| JPS5949191A (en) * | 1982-09-13 | 1984-03-21 | 松下電器産業株式会社 | High frequency heater |
| EP0173491B1 (en) * | 1984-08-14 | 1989-11-08 | Microwave Ovens Limited | Microwave oven |
| DE3585945D1 (en) * | 1984-11-20 | 1992-06-04 | Matsushita Electric Ind Co Ltd | DOOR STRUCTURE FOR MICROWAVE HEATER. |
| DE3607557A1 (en) * | 1986-03-07 | 1987-12-23 | Bosch Siemens Hausgeraete | MICROWAVE OVEN |
| GB8609937D0 (en) * | 1986-04-23 | 1986-05-29 | Microwave Ovens Ltd | Microwave ovens |
| FR2639170B1 (en) * | 1988-11-17 | 1991-01-11 | Dietrich & Cie De | DOOR FOR MIXED COOKING CABINET HAVING A FLOATING WAVE TRAP |
| KR100512247B1 (en) * | 2003-08-25 | 2005-09-05 | 엘지전자 주식회사 | Structure of choke using interception electromagnetic wave |
| DE102004003406A1 (en) * | 2004-01-23 | 2005-08-18 | Electrolux Schwanden Ag | A method for constructing a door for microwave ovens has an inner frame forming a quarter wavelength pocket around the opening and a smaller gap to the housing |
| US9119234B2 (en) | 2010-03-23 | 2015-08-25 | Panasonic Intellectual Property Management Co., Ltd. | Drawer-type heating apparatus |
| EP3087808B1 (en) * | 2013-12-23 | 2022-02-09 | Whirlpool Corporation | Multiple cavity microwave oven door |
| EP3497372B1 (en) | 2016-08-11 | 2021-07-07 | Whirlpool Corporation | Divider assembly for a microwave oven |
| CN110107929B (en) * | 2019-04-15 | 2024-05-28 | 青岛笈美创意科技有限公司 | Microwave heating system for box lunch vending machine |
| US20220205639A1 (en) * | 2019-07-31 | 2022-06-30 | Sharp Kabushiki Kaisha | Heating cooking apparatus |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2782292A (en) * | 1952-04-17 | 1957-02-19 | Gen Motors Corp | Domestic appliance |
| US2778911A (en) * | 1952-08-12 | 1957-01-22 | Gen Motors Corp | Domestic appliance |
| CH442563A (en) * | 1965-08-26 | 1967-08-31 | Karl Dr Fritz | Microwave ovens for household and catering |
| US3440385A (en) * | 1965-10-13 | 1969-04-22 | Microtherm Ltd | Electronic ovens |
| JPS5011108B1 (en) * | 1970-03-03 | 1975-04-26 | ||
| US3662139A (en) * | 1970-03-04 | 1972-05-09 | Varian Associates | Cavity resonator having means for reducing leakage of r.f. energy at a covered access point |
| CA1030613A (en) * | 1974-06-14 | 1978-05-02 | Amana Refrigeration | Microwave energy oven seal |
| CA1054231A (en) * | 1975-03-31 | 1979-05-08 | Arnold M. Bucksbaum | Microwave oven door seal system of resonant transmission line structure |
| US4013861A (en) * | 1975-08-13 | 1977-03-22 | The Frymaster Corporation | Microwave oven door seal |
-
1978
- 1978-04-10 CA CA300,742A patent/CA1111505A/en not_active Expired
- 1978-07-25 CH CH799078A patent/CH632627A5/en not_active IP Right Cessation
- 1978-07-27 GB GB7831396A patent/GB2002210B/en not_active Expired
- 1978-07-27 DE DE19782833040 patent/DE2833040A1/en not_active Ceased
- 1978-07-28 IT IT7826220A patent/IT1097788B/en active
- 1978-07-31 AU AU38498/78A patent/AU521773B2/en not_active Expired
- 1978-07-31 FR FR7822634A patent/FR2399780A1/en active Granted
- 1978-08-01 YU YU1867/78A patent/YU41111B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| FR2399780A1 (en) | 1979-03-02 |
| GB2002210A (en) | 1979-02-14 |
| DE2833040A1 (en) | 1979-02-22 |
| CH632627A5 (en) | 1982-10-15 |
| IT7826220A0 (en) | 1978-07-28 |
| IT1097788B (en) | 1985-08-31 |
| FR2399780B1 (en) | 1984-10-26 |
| AU521773B2 (en) | 1982-04-29 |
| YU186778A (en) | 1982-10-31 |
| AU3849878A (en) | 1980-02-07 |
| YU41111B (en) | 1986-12-31 |
| GB2002210B (en) | 1982-05-19 |
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