JPH07246156A - Rice cooker - Google Patents

Abstract

PURPOSE:To provide a very low-priced and safe rice cooker for consumers by improving the noise suppression property of electronic circuit boards with a simple configuration. CONSTITUTION:A rice cooker with high shield performance is made by providing a main body 1, an inner pot 2 detachably contained in the main body 1, an induction coil 7 at the bottom of the inner pot 2 in the main body l, an electronic circuit board 9 to control the continuity to the induction coil 7 set under the induction coil 7, and an antimagnetic plate 10 formed in a saucer comprising aluminum alloy, etc., between the induction coil 7 and the electronic circuit board 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rice cooker for cooking rice in an inner pot by an electromagnetic induction heating method, and relates to a rice cooker for shielding a high frequency magnetic field generated by an induction coil from leaking to the outside.

[0002]

2. Description of the Related Art Conventionally, this type of rice cooker has a problem that if a high frequency magnetic field generated by an induction coil leaks, an article (pot, spoon, etc.) made of a magnetic material placed near the main body may generate heat due to induction heating, and There was a problem such as noise entering the radio etc. As an invention for solving this problem, for example, Japanese Patent Application Laid-Open No. 1-302680 is known. This invention is an inner pot that is detachably housed in the main body,
The storage part of the inner pot in the main body is composed of an inner container bottom made of a non-metallic material such as resin that does not generate heat by induction heating. A magnetic shield ring made of aluminum plate is installed side by side to absorb the high frequency magnetic field generated from the induction coil by the magnetic shield ring and obtain a shield effect that does not leak to the outside.

The structure of a conventional example is shown in FIG. 101 is a rice cooker body in which an inner pot 102 is detachably housed. 1
A lid 03 covers the upper openings of the main body 101 and the inner pot 102 so as to be openable and closable. An inner container 104 is provided inside the main body 101 so as to wrap the side of the inner pot 102, and an inner container bottom 105, a coil base 106, and an induction coil 1 formed of a heat-resistant plastic inside the bottom of the inner container 104.
There is provided a coil unit that is integrally configured with 07.

Ferrite 108 is adhered to the back surface of the coil base 106 to enhance the inductive coupling and to prevent the outside from being magnetized. A board case 111 made of plastic is provided below the coil unit, and the pattern surface side of an electronic board 109 for controlling the energization of the induction coil 107 is fixedly installed on the board case 111.
Further, an annular magnetic shield ring 110 made of an aluminum plate is provided on the outer peripheral side of the coil unit. Board case 1
The high-frequency magnetic field generated from the induction coil 107 is absorbed by 11 and the magnetic shield ring 110, and a shielding effect that does not leak to the electronic substrate 109 and the outside is obtained.

As another example, for example, Japanese Patent Laid-Open No. 5-1153 / 1991.
As shown in Japanese Patent Laid-Open No. 58-58, there is a method in which the electronic board is provided outside the magnetic shield ring without using the board case and the electronic board is separated from the induction coil.

[0006]

In the structure of the conventional rice cooker, the magnetic shield ring 110 is provided only on the side surface of the induction coil 107, and it is difficult to obtain a sufficient shield effect because it cannot cover the wide area of the side surface. In order to obtain a sufficient effect, it is necessary to provide the magnetic shield ring 110 that is wide from the upper side to the lower side of the side surface portion, which causes a problem of high cost.

Further, this structure has little effect on the downward magnetic field leakage of the induction coil 107. By installing the ferrite 108 as shown in FIG. 3, the inductive coupling is enhanced and the magnetic field is leaked downward to the outside. Had to be prevented. However, since the ferrite 108 has a plurality of rod-shaped objects arranged radially, there is a magnetic field slightly leaking from between the ferrites, and the electronic substrate 10 provided inside the main body 101.
9 acts to cause noise other than the normal signal, which causes malfunction. There is a method of increasing the number of ferrites 108 to solve this problem.
No. 8 is expensive, and there is also a drawback that the attachment work time increases because an elastic adhesive is used for attaching the ferrite 108.

The board case 111 installed between the induction coil 107 and the electronic board 109 blocks the magnetic flux from the induction coil 107 to some extent, but the board case 111 is required in addition to the magnetic shield ring 110, and the number of parts is large. There was a flaw. In addition, the electronic board provided on the outer side of the magnetic shield ring has drawbacks that the wiring work at the time of assembling the product becomes very difficult and the lead wire becomes long and complicated, resulting in high cost.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and includes a main body, an inner pot removably housed in the main body, and an induction coil provided at the bottom of the inner pot in the main body. And a rice cooker consisting of an electronic board for controlling energization of the induction coil provided below the induction coil, a saucer-shaped magnetic shield plate made of aluminum alloy or the like is provided between the induction coil and the electronic board. It is a thing.

[0010]

According to the structure of the present invention, the magnetic flux generated from the induction coil during rice cooking and consumed by the heat generated in the inner pot is consumed by the ferrite and the magnetic shield. In addition, since the Joule heat generated in an aluminum alloy or the like having a low specific resistance value is much smaller than that in an iron pot or the like, it is not affected by heat on the main body and the electronic substrate.

Therefore, even if there is no magnetic shield ring or substrate case, the magnetic shield provided between the induction coil made of aluminum alloy or the like and having a saucer shape and the electronic substrate completely shields the side surface and the bottom surface of the induction coil. Further, the upper surface of the induction coil does not need to be magnetically shielded because there is an inner pot to be heated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view of a rice cooker to which an embodiment of the present invention is applied, and FIG. 2 is a perspective view of a main part of the rice cooker.

In the figure, reference numeral 1 is a main body of a rice cooker, and an inner pot 2 for cooking rice is detachably housed in the main body 1. A lid 3 covers the upper openings of the main body 1 and the inner pot 2 so as to be openable and closable. The inner pot 2 is formed of a clad steel plate whose outer surface is magnetic. In addition, the inner pot 2 is provided inside the main body 1.
The inner container 4 is provided so as to wrap the side of the inner container 4, and a coil unit integrally formed of the inner container bottom 5, the coil base 6, and the induction coil 7 is provided inside the bottom of the inner container 4.

A ferrite 8 is adhered to the back surface of the coil base 6 to enhance the inductive coupling and to protect the outside from the magnetic field. An electronic board 9 for controlling energization to the induction coil 7 is installed below the induction coil 7 with a magnetic shield 10 sandwiched therebetween. The magnetic shield 10 is a dish-shaped plate of aluminum or aluminum alloy having a small specific resistance value.

Next, the operation of this embodiment having the above structure will be described. When the user puts the washed rice and the appropriate amount of water in the inner pot 2 into the inner container 4 and closes the lid 3 and starts the operation of the rice cooker, a large current flows to the induction coil 7 and around the induction coil 7. A magnetic field is evenly generated and a magnetic flux flows. Most of the magnetic flux heats the inner pot 2 to heat the rice and water in the inner pot 2 to cook rice.

At this time, the magnetic flux other than that consumed for heating the inner pot 2 adversely affects the outside of the main body 1. Providing only the ferrite 8 enhances the inductive coupling and prevents the magnetic field from leaking below the ferrite 8. However, in order to completely prevent the magnetic field from leaking, it is necessary to arrange a large number of ferrites 8 densely. A slight magnetic field leaks downward from between 8 and acts on the electronic substrate 9 to cause noise other than the normal signal in the circuit.

The ferrite 8 adhered to the coil base 6 attached to the lower surface of the induction coil 7 and the magnetic shield 10 shaped like a saucer can block the magnetic flux from the induction coil 7 and prevent the magnetic field from being applied to the electronic substrate 9. Completely prevent leaks.

With this, since the circuit malfunction due to noise can be prevented, the substrate case between the induction coil 7 and the electronic substrate 9 becomes unnecessary, and the pattern surface of the electronic substrate 9 can be installed facing the induction coil 7. The workability in assembling is improved, and the number of ferrites 8 can be reduced due to the improvement of the magnetic shielding to the outside and the electronic substrate 9. Further, by forming the magnetic shield 10 in the shape of a saucer, it has the function of a magnetic shield ring, and even if the inner container 4 is provided with a hole for some reason, it has an effect of preventing water from entering the electronic substrate 9.

[0019]

As described above, according to the present invention, since the magnetic shield plate formed in the shape of a saucer such as an aluminum alloy having a small specific resistance value is provided between the induction coil and the electronic board, the magnetic flux from the induction coil can be completely cut off. The circuit malfunction due to noise can be prevented, and the board case between the induction coil and the electronic board is not required, and the pattern surface of the electronic board can be installed facing the induction coil, improving the workability in assembly. In addition, it is possible to reduce the number of ferrites by improving the magnetic protection to the external and electronic boards. Further, by forming the magnetic shield plate in the shape of a saucer, it has the function of a magnetic shield ring, and has the effect of preventing water from entering the electronic substrate even if a hole or the like is provided in the inner container for some reason. Therefore, an inexpensive and safe rice cooker can be provided to consumers.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a rice cooker showing an embodiment of the present invention.

FIG. 2 is a perspective view of a main part of the rice cooker.

FIG. 3 is a cross-sectional view of a rice cooker showing a conventional example.

[Explanation of symbols]

 1 Main Body 2 Inner Kettle 7 Induction Coil 9 Electronic Board 10 Magnetic Shield Plate

Claims (1)

[Claims] 1. A body (1), an inner pot (2) removably housed in the body (1), an induction coil (7) provided at the bottom of the inner pot (2) in the body (1), A rice cooker comprising an electronic board (9) provided below the induction coil (7) for controlling energization of the induction coil (7), wherein a saucer is provided between the induction coil (7) and the electronic board (9). A rice cooker, which is provided with a magnetic-shield plate (10) made of aluminum or an aluminum alloy formed into a strip shape.