Temperature sensing probe for microwave oven application

A connector of temperature sensing probe for a microwave oven which connects to the control circuit of the microwave to rotate together with a turntable while being inserted in the food being cooked. A plug which is provided in one end of the temperature sensing probe is inserted along a plug guide into a connector, and is sandwiched by elastic parts composed of first and second springs. When the plug revolves with the rotation of the turntable, the cylinder itself also rotates, cause the lead to output temperature data from the probe via the contact elements. As a result, due to the minimum number of parts used, the connector embodied by the present invention has an extremely compact and simple structure, enabling the temperature sensing probe to freely rotate, thus resulting in a reduced cost for both material and assembly.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates to a connector for a temperature sensing 
probe of a microwave oven, and more particularly, to a device that 
connects a temperature sensing probe to the control circuit of the 
microwave oven, wherein said temperature sensing probe is inserted into 
the food being cooked rotates together with the turntable of the microwave 
oven. 
A typical microwave oven incorporating heat control means that respond 
varying temperature and which can be monitored during the food cooking 
operation is already commercially available. Such a microwave oven is 
designed so that the temperature can be properly controlled, for example, 
by inserting a temperature sensing probe containing a thermister 
incorporated in the tip portion of a metal needle tube into the food in 
order that temperature data detected by the thermister can be sent to the 
heat source control circuit such as a magnetron of the microwave oven. 
On the other hand, while operating a microwave oven that uses a turntable 
for rotating the food during the cooking operation and the temperature 
control means mentioned above, the food being cooked rotates together with 
the temperature sensing probe. This makes it quite necessary that the 
temperature sensing probe be properly connected to the microwave oven so 
that it can freely rotate throughout the cooking operation. 
As shown in a sectional view in a conventional connector of FIG. 1 and the 
plane view thereof in FIG. 2, a typical device connected to a freely 
rotating temperature sensing probe incorporates a structure comprising 
bushes 2a and 2b in choke 1 that is secured to the microwave oven unit so 
that the relay jack 3 is freely rotatably supported by bushes 2a and 2b. A 
plug connected to one end of the temperature sensing probe is inserted 
into the relay jack 3 in order that the plug can rotate together with the 
relay jack, thus causing the contact elements 4a and 4b to be elastically 
placed into contact with guide plates 41 and 42 that are provided at one 
end of the relay jack 3, and enabling the temperature data to be record. 
Details of this mechanism were disclosed by U.S. Pat. No. 4,149,056 
"MICROWAVE OVEN WITH FOOD TEMPERATURE-SENSING MEANS" to Kaneshiro et al. 
With reference to the mechanism of the conventional connector discussed 
above, not only the guide plates 41 and 42, but also a variety of parts 
such as a plug hold spring 33', a jack cylinder 44, and many other 
elements are required for the relay jack 3. In addition, since the 
connector has a complex structure, it cannot be easily produced. As a 
result, the cost still remains very high. 
In the light of such disadvantages, the present invention is primarily 
directed to providing a connector that enables a rotating temperature 
sensing probe to be effectively connected to the connector while at the 
same time being composed of a simple structure by minimizing the parts 
being used. 
A preferred embodiment of the present invention provides an improved 
connector of the temperature sensing probe for connection with the control 
circuit of a microwave oven to permit the probe to freely rotate together 
with the turntable when it is inserted into food during the cooking 
operation. More particularly, an improved connector comprises a freely 
rotating cylinder made of an insulation material, which is installed in a 
choke secured to the microwave oven unit. The connector contains first and 
second springs which are made of a conductive material and secured to the 
cylinder, one end of which makes up a plane surface along one end of the 
surface of the cylinder. The other end thereof makes up an elastic part 
along the inner surface of said cylinder, and the first and second contact 
elements elastically come into contact with the plane surfaces of the 
first and second springs. A plug at the tip portion of said probe is 
supported by the elastic parts of both the first and second springs, and 
as a result, the plug is supported by said choke in a freely rotating 
state via said cylinder, thereby eventually allowing said contact elements 
to send out the temperature data detected by the temperature sensing 
probe. 
Another preferred embodiment of the present invention provides means, in 
which the choke lid secured to the microwave oven unit is made a throttle 
plate, whereas a cylinder of a large diameter is projectively installed in 
the center position of said choke lid via an opening which passes through 
the plug of the temperature sensing probe to enable the choke lid and 
choke itself to be coupled together. If necessary, a spacer is provided in 
the choke opening so that the spacer behaves as a guide to enable the plug 
of said probe to be inserted into said opening.

DETAILED DESCRIPTION OF THE INVENTION 
With reference to the attached drawings, the preferred embodiments of the 
present invention are described below. 
FIG. 3 is a sectional view of the connector as a preferred embodiment of 
the present invention. FIG. 4 is a plane view of the connector shown in 
FIG. 3 seen from the upright position. 
Choke 6 secured to the microwave oven unit 5 is provided with a cylinder 7 
which is made of an insulation material, for example, plastics. The 
cylinder 7 is securely provided with a first spring 8 and a second spring 
9 which are respectively shown in the perspective views of FIGS. 5 and 6. 
The first spring 8 is composed of a pair of the elastic parts 8b and 8b 
protruding from a circular plane part 8a. Likewise, the second spring 9 
has a pair of elastic parts 9b and 9b protruding from a circular plane 
part 9a. These elements are unitedly composed of conductive material, for 
example, a copper alloy, finished with nickel plating. 
The first and second springs 8 and 9 are arranged so that their plane parts 
8a and 9a correctly lay on the surface of the cylinder 7, while the 
elastic parts 8b and 9b also correctly meet the internal surface of said 
cylinder. Circular plane parts 8a and 9a of the first and second springs 8 
and 9 are elastically held in contact with the first and second contact 
elements 10a and 10b, while leads 11a and 11b are connected to contact 
elements 10a and 10b, respectively. A plug guide 12 is installed to choke 
6 on the identical axis to that of the cylinder 7. 
When the plug 14 in one end of the temperature sensing probe 13 is inserted 
along the plug guide into the connector, plug 14 is sandwiched by elastic 
parts 8b and 9b of the first and second springs 8 and 9. 
When the plug 14 is revolved by the rotation of the turntable, cylinder 7 
also rotates so that temperature data from the temperature sensing probe 
are sent to leads 11a and 11b via the contact elements 10a and 10b. 
FIG. 7 shows a sectional view of the main part of a connector according to 
another preferred embodiment of the present invention, whereas FIG. 8 is 
an exploded view of the connector shown in FIG. 7. This represents a 
slipping connector to which an output terminal of the temperature sensing 
probe 13 that detects temperature of the food being cooked on the 
turntable of a microwave is connected, while said connector incorporates a 
circular choke made of throttle metal plate having its structure divided 
into a bore and outer diameter parts, and yet the bore contains a mobile 
contact that permits an output terminal to be freely connected or 
disconnected in the center space of the bore. As a result, since the choke 
part is made of a throttle metal plate, it is cheaper than a diecast 
substrate, while the connector can be made up in a compact size, since it 
contains a mobile contact in the center space of the choke bore. 
Referring to FIG. 7, reference numeral 21 is a choke lid secured to wall 22 
of the cooking chamber of a microwave oven by screws. Cylinder 25 contains 
a choke which is about 5 mm high and wider than the circular opening 
through which a plug 24 of the temperature sensing probe passes, while 
said cylinder 25 is projectively installed in the center space surrounded 
by the throttle metal plate. Cylindrical choke 26 is connected to the 
choke lid 21 by calking, while a choke opening 27 is provided in the upper 
edge 25' of said cylinder 25. Sliding pipe 28 made of a friction-free 
resin such as "TEFLON" is in contact with plug 24 which is installed in 
the opening 27 of said choke. 
FIG. 8 is an exploded view of said connector, in which, the first 
cylindrical rotor 29 being installed to said choke 26 in a free rotational 
state is internally provided with the second cylindrical rotor 30 that is 
tightly inserted into and coupled with said first rotor 29. The first 
elastic part 31 secured to the internal part of the second cylindrical 
rotor 30 is finished with nickel plating over its surface. The plug 24 is 
inserted into the connector, and the first elastic part 31 elastically 
contacts the ground of said plug 24. 
Reference number 32 denotes the second elastic part that elastically comes 
into contact with the tip portion 24' of said plug 24 that transmits 
signals detected by a thermister (not illustrated) of the temperature 
sensing probe 23. The second elastic part is made of a nickel-plated 
phosphorated bronze plate, which is secured to the center position of the 
first rotor 29 via an auxiliary plate 33. Reference number 34 denotes a 
terminal base that is secured to the upper surface of the choke 26 by 
screws, which provides the first contact sheet 35 that is pressed against 
the upper surface of the first elastic part 31 and the second contact 
sheet 36 pressed against the upper surface of the second elastic part 32, 
while said contact sheets 35 and 36 are respectively connected to the 
control circuit of the microwave oven unit, to which temperature data of 
the food detected by the thermister is transmitted. 
The effect of arranging a cylinder 25 of about 5 mm in height in the center 
position of the choke lid 21, which is secured to wall 22 of the cooking 
chamber by screws with said cylinder tightly inserted into the choke 6 
results in an attenuation which is as effective as the case in which the 
choke inlet is moved away from the inner part even if the choke opening 27 
of the choke 26 is provided in a lower position, proving that it is an 
advantageous choke structure. 
As a result, screwing holes can be provided through the wall of the cooking 
chamber to permit the connector to be properly secured with screws at a 
position where the choke effect near the choke inlet is rarely affected, 
thus allowing the connector to be securely installed. 
Another preferred embodiment of the present invention is characterized by 
the simplified method of installing both the choke lid and choke as a 
result of the connection of the choke lid and choke by making up said lid 
with a metal throttle plate secured to the microwave oven and by 
projectively installing a cylinder having a greater diameter than the 
opening which permits the plug of the temperature sensing probe to enter 
into the center position of the choke lid. This embodiment is also 
characterized by effectively preventing microwave leakage because the 
projectively installed cylinder ensures a satisfactory choke effect, even 
if the choke opening is internally provided, i.e., in a position adjacent 
to the cooking chamber. It provides a still further advantage in that the 
choke unit can be securely installed to the microwave oven, since screw 
holes can be provided in such portions where the choke effect near the 
choke inlet is rarely affected. Since the above preferred embodiment 
provides the choke opening of the choke near the wall of the cooking 
chamber and a spacer that guides the plug of the temperature sensing probe 
to correctly enter the choke opening, the connection parts such as contact 
sheets that respectively come into contact with the plug of the 
temperature sensing probe at a position apart from the cooking chamber 
wall and the lead terminals to be connected to the control circuit of the 
microwave oven can be compactly arranged, thus enabling the connecter to 
be built in a very compact size. 
As clear from the above detailed description, the preferred embodiments of 
the present invention typically provide simple structures of connectors by 
minimizing the parts required, thus allowing the temperature sensing probe 
to be properly connected in a free rotational state and eventually 
minimizing the cost needed for the materials and assembly as well. 
The present invention thus described in reference to the annexed drawings 
will obviously be suggestive of any derivation or modification from the 
spirit and scope contained therein by those skilled in the arts. It should 
be understood, however, that the present invention is not limitative 
within the spirit and scope described therein, but is intended to solely 
include all of such derivations and/or modifications within the spirit and 
scope of the following claims.