JPH04371724A - Microwave oven - Google Patents

Abstract

PURPOSE:To provide a microwave oven capable of arbitrarily heating the whole of foodstuffs or a part of foodstuffs in a surface wave heating system, making the checking of heating conditions of the foodstuffs easier, and further simply automating surface wave heating to an optimum state. CONSTITUTION:The title oven is provided with: heating plates 5 for heating microwaves oscillated from a microwave oscillation source 2, in a surface wave propagation mode; variable mechanisms 6 for varying the surface wave propagation mode of the heating plates 5 according to the kinds of foodstuffs; a heating chamber 1 covering up the upper portions of the heating plates 5 with a cover 14 consisting of a transparent body having a microwave shielding mechanism; a detecting means 10 for detecting a microwave absorbing quantity of foodstuffs in the heating chamber 1; and a regulating means 11 for regulating the variable means according to a signal from the detecting means 10. This constitution makes it possible to achieve the purpose of cooking.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency heating device for heating food.

0002

2. Description of the Related Art A conventional high-frequency heating device heats food 4 by emitting high-frequency waves from a high-frequency oscillation source 2 in a closed space in which a heating chamber 1 is entirely surrounded by metal, as shown in FIG. There is. Therefore, the food 4 was heated in the heating chamber 1 by the standing wave mode 12 generated by the heating chamber wall. Furthermore, the door (not shown) is provided with punched holes to prevent high-frequency waves from leaking to the outside in order to take the food 4 in and out of the heating chamber 1 and check the heating status of the food. A turntable 13 is provided to improve the heating distribution of the food 4 in the heating chamber. In this way, the entire food 4 was heated from the inside by high frequency heating. Note that 3 is a power source that supplies power to the high frequency oscillation source 2;
8 is a cooling fan that cools the high frequency oscillation source 2.

On the other hand, apart from such standing wave mode heating methods, there is also a heating method in which the electric field is concentrated near the food by surface wave heating (for example, Japanese Patent Publication No. 47-3877
Publication No. 8).

0004

[Problem to be solved by the invention] However, the above figure 4
With conventional configurations, there were problems in that the entire food was heated, making it difficult to brown the food, and that a temperature gradient could not be achieved depending on the type of cooking. In addition, since there are punched holes, it is difficult to check the internal heating status.

[0005] Furthermore, in the conventional surface wave heating method, the electric field is concentrated in the vicinity of the food, so although the problem shown in FIG. (For example, there were times when the side near the concentration of the electric field was heated, but the side opposite to it was not heated.)

[0006] Furthermore, realizing the optimum surface wave propagation mode depending on the shape, amount, and type of food requires extremely complicated operations for the user.

The present invention solves the above problems, and provides a high-frequency heating device that uses a surface wave heating method to uniformly heat the entire food, makes it easy to check the heating status, and easily achieves the optimum surface wave heating state. It is intended to provide.

[0008]

[Means for Solving the Problems] In order to achieve the above objects, the present invention includes a high frequency oscillation source that oscillates high frequency waves, and a periodic structure heating plate that heats the high frequency waves oscillated from the high frequency oscillation source in a surface wave propagation mode. a variable mechanism that changes the surface wave propagation mode of the heating plate depending on the type of food; a heating chamber surrounding the heating plate with a lid having a radio wave shielding mechanism; and detecting the amount of radio waves absorbed by the food in the heating chamber. The configuration includes a detection means and an adjustment means for adjusting the variable means based on a signal from the detection means.

[0009]

[Operation] With the above configuration, the present invention detects the degree of high frequency absorption of the food on the heating plate, and the adjustment means automatically adjusts the surface wave heating propagation mode so that the high frequency is efficiently absorbed by the food. It has an effect.

0010

[Embodiment] An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, 1 is a heating chamber surrounded by a lid 14 made of heat-resistant transparent resin and has a radio wave shielding mechanism made of a conductive film, 2 is a magnetron which is a high frequency oscillation source, and 3 is a heating chamber surrounded by a lid 14 made of heat-resistant transparent resin.
is a power source that supplies power to the magnetron, 4 is a food product, 5 is a heating plate of a periodic structure that produces a surface wave heating mode, 6 is a variable mechanism that changes the propagation mode of surface wave heating, 7
8 is an antenna for exciting high frequency waves from the magnetron 2 on the heating plate 5; 8 is a cooling fan that cools the magnetron 2; and 9 is a resin that covers the periodic structure. 10 is a detection means for detecting the degree of absorption of high frequency waves into the food on the heating plate, and 11 is an adjustment means for adjusting a variable mechanism based on a signal from the detection means to change the propagation mode of surface wave heating.

FIGS. 2 and 3 are explanatory diagrams of a periodic structure for explaining surface wave heating. Surface wave heating utilizes total reflection of radio waves, and by forming a periodic structure with grooves as shown in FIG. 2, radio waves can be concentrated near the surface. Figure 3 shows the equivalent circuit, where the characteristic impedance is Z0, the concentrated impedance is Z1, the phase constants of each space are βO, βP, the phase constant in the Z direction is βZ, and the periodic pitch is p. As an equation, cosβZ p=cosβO p+(Z1 /2Z
0 )・sin βP holds true.

In the grooved structure shown in FIG. 2, if the depth a and pitch p of the grooves are selected appropriately for the wavelength λ of the frequency used, radio waves traveling perpendicular to the transmission direction Z are blocked by the grooves. The waves meet the area, or are completely reflected at the interface between the groove surface and the free space, creating a standing wave, which ultimately propagates only in the Z direction. Further, the propagation of radio waves in the X direction decreases exponentially (Floquet's theorem, Kindai Kagakusha, Microwave Engineering Volume 2, P, 462 to P, 464).

Therefore, by making the heating plate 5 a periodic structure and providing the variable mechanism 6 that changes the depth of the grooves, it is possible to concentrate the electric field on the food 4 and to reduce the radio waves exponentially in the X direction. can also be changed. In other words, the purpose is to loosen the degree of concentration in the Z direction and increase the intensity of radio waves in the X direction.

In the above configuration, when the depth of the groove is increased, the concentration of radio waves increases near the surface of the groove, so when browning meat, the variable mechanism 6 is adjusted to deepen the groove, and If you want to heat the inside, you can make the depth of the groove shallower, reduce the concentration of the electric field, and heat the entire area. Further, in order to prevent leakage of radio waves into free space, it is preferable to provide a lid 14 having a radio wave shielding mechanism such as punched holes on the heating plate 5. Furthermore, in order to make the inside clearly visible, the heating chamber 1 may be provided surrounded by a lid 14 made of a heat-resistant transparent resin and having a radio wave shielding mechanism that reflects radio waves with a conductive film or the like. This configuration prevents radio waves from leaking and irradiating the human body. Note that the heat-resistant transparent resin is not limited to this, and any transparent material such as glass or ceramic may be used. Furthermore, in the above description, the case where the whole food is surrounded by a transparent transparent body was explained, but since it is good if the browned state of the food 4 can be clearly seen, the whole food does not necessarily have to be transparent, and only a part of it can be transparent. You can.

[0016]

[Effects of the Invention] As explained above, the high frequency heating device of the present invention has the following effects. (1) Optimal surface wave heating is achieved by adjusting the variable mechanism that changes the surface wave propagation mode of the heating plate based on the signal from the detection means, and a heating method that does not cause uneven heating can be easily realized. In addition, since the variable mechanism is adjusted according to the shape, type, and amount of food, there is no troublesome operation, and the usability is improved. (2) Since a lid made of a heat-resistant transparent material having a radio wave shielding mechanism is used in at least a portion of the heating chamber, the finished state of the food inside can be clearly observed.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view showing the overall configuration of a high-frequency heating device in an embodiment of the present invention.

[Fig. 2] Diagram of a periodic structure explaining surface wave heating according to an embodiment of the present invention.

[Fig. 3] Equivalent circuit diagram of a periodic structure explaining surface wave heating according to an embodiment of the present invention.

[Figure 4] Partial cross-sectional view showing the configuration of a conventional high-frequency heating device

[Explanation of symbols]

1 Heating chamber 2 High frequency oscillation source 4 Food 5 Heating plate 6 Variable mechanism 10 Detection means 11 Adjustment means 14 Lid

Claims (2)

[Claims] 1. A high-frequency oscillation source that oscillates high-frequency waves; a periodic structure heating plate that heats the high-frequency waves oscillated from the high-frequency oscillation source in a surface wave propagation mode; a variable mechanism for changing intensity; a heating chamber provided between the heating plate and a lid having a radio wave shielding mechanism surrounding the heating plate; a detection means for detecting the amount of radio waves absorbed by food in the heating chamber; and adjusting means for adjusting the variable means according to a signal from the means. 2. The high-frequency heating device according to claim 1, wherein at least a portion of the lid is a transparent body equipped with a radio wave shielding mechanism.