JPS58176895A - Microwave heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in microwave heating devices. Hitherto, various microwave heating devices have been proposed that utilize microstrip lines in which a ladder pattern is formed on the center conductor or ground conductor (for example, Japanese Patent Applications No. 55-108444 and No. 56-112729).

However, in these conventional examples, among the slits forming the ladder pattern, the microwave is largely reflected at the rear end edge of the slit in the most consuming part (the same end facing the microwave supply lIl). However, standing waves are generated, and there is a risk that so-called "uneven baking" may occur in the heated object.

The reason for this is thought to be that the characteristic impedance of the microstrip line changes (decreases) drastically at the rear edge of the rearmost slit. Therefore, when a thin object to be heated, as shown in Figure 1, is scanned over the ladder pattern in the direction of the arrow, only the shaded area (where standing waves are generated) will be heated strongly, and the other areas will be heated. This means that the trench will not be heated. To explain this situation in more detail with reference to FIG. 2, in this figure, the nine curves indicated by solid lines are traveling waves (2) propagating in the microstrip line. In addition, the nine curves indicated by the one-dot chain line are the reflected waves of the traveling wave reflected at the reflecting surface (at the rear edge of the rearmost slit).The nine curves indicated by the zero-dot chain line are , is a standing wave (q) that is generated by combining the traveling wave in l and the reflected wave (b).As can be seen from this figure, there is a part (c) that reflects the traveling #IL (g). and a standing wave (q) will be generated.

Therefore, if only this reflective surface (g) was removed, the permanent wave 0 could be prevented from occurring, but this is practically difficult.

Therefore, without eliminating the standing waves, we can calculate the position where the standing waves occur by λ・n/2+λ/4 (λ is the effective wavelength of the microwave,
In order to reciprocate by the same dimension as (n is an integer) and to heat all the items to be heated equally, a device was proposed in which a means was provided to periodically short-circuit the front and rear edges of the slit at the rearmost end. (For example, Tokusho No. 54-191209), however, what is described in the clear summary and drawings of this patent application 1982-191201Hj is a structure in which a ladder pattern is formed in which a strong V% electric field is concentrated. - Because short circuits and opens occur repeatedly in the ground conductor part, sparks are generated (there is a risk of damage to the ground conductor). I couldn't.

The present invention has been made in view of the female point of prayer, in which a conductive member is brought into contact with or close to the conductor on the '& side where a ladder pattern is formed, and the position is changed to where a standing wave is generated. This is what we do.

Hereinafter, examples of the present gloss will be described with reference to the drawings below the Wj black diagram.

FIG. 5 is a perspective view showing an embodiment of the present invention, FIG. 4 is a side view thereof, and FIG. 5 is a back view thereof. In these figures, (1) is a five-tube tunnel. This microstrip vA path txt consists of a dielectric substrate (2) formed of a dielectric material such as fluoroethylene, a ground conductor (3) made of steel that can be pasted on the upper surface of this substrate, and a ground conductor (3) made of steel on the lower surface. The center conductor (the ground conductor IJI) K is made up of 4 pieces (the inside of which is pasted) and the center conductor (the ground conductor IJI) K is connected to the slab [(5j・- is plural) along the microwave propagation direction. In this embodiment, each slit (to) is formed at a non-perpendicular angle to the propagation of the microwave. ) is a coaxial cable for supplying microwaves to the microwave. (9) is a rectangular gold 1+1vi as a conductive member provided so as to be in contact with the lower surface of the center conductor (4), and is connected to the same rotation axis I of the motor. The distance between this rotation center and the rear edge of the microstrip 4 circuit (1) is set to λ/4 (λ is the effective wavelength of the microwave within the microstrip 411 circuit). In addition, the center conductor [3] and the metal plate (91 is micros) tap line (1
) They do not necessarily need to be in contact, as long as they are close enough to change the characteristic impedance of the two.

The metal plate +97 does not need to be placed in a square shape as long as it is non-circular. be transported.

When the gold lR plate (9) rotates while slidingly contacting the center conductor +47, the microwave in the microstrip line (1) vibrates as follows. When the direction of the metal plate (9) is parallel to the propagation direction of the microwave, the impedance does not change significantly at that point.Therefore, the microwave mainly flows through the center conductor (4). The zero-order metal plate (force 90 @ When it rotates and its grip is perpendicular to the direction of microwave propagation,
At that point, the impedance changes significantly. Therefore, the microwave is reflected at the orthogonal portion of the center conductor (4) and the metal plate (9), and the accompanying standing waves are generated. Therefore,
As the gold plate (9) rotates, the positions where the standing waves are generated are separated by λ/4 and intermittently reciprocate between 92 positions. ) The state of changing hinge heating distribution mt will be explained according to FIG. α■ moves in the direction of the arrow on the copy paper, and the shaded area shows the heated part of the copy paper (13). Heating state when the 0-σ line part of the copy paper 11 approaches the ladder pattern 16) and the direction of the force applied to the metal Wi+91 is perpendicular to the propagation direction of the mital wave. This shows that. As you can see from this figure, the Am III board (9) is!
0'' When one rotation is made, the standing wave becomes λ/4f) by the dimension Vf)f
As the metal plate (9) continues to rotate, a heating distribution as shown by the shaded area in FIG. 7 occurs. Therefore, when the metal plate (9) is rotated at a high speed compared to the scanning speed of the copy paper 02, the entire surface is heated uniformly.

In addition, in the above embodiment, Life I! ! Although the distance between the center of rotation of the plate (9) and the rear edge of the microstrip line (1) was set to λ/4, it may be λ・n+J/4 (n is a positive integer). When it is not necessary to uniformly heat the copy paper 13 over the entire surface, a metal plate (9) is used.
The distance between the rotation center of the microstrip line (11) and the rear edge of the microstrip line (11) can be set arbitrarily.
In order to increase the change in characteristic impedance caused by the rotation of the central conductor (4), the portion of the center conductor (4) that contacts the metal plate (9) may be made narrower than the other portions.

FIGS. 8 and 9 are side and back views of other embodiments. In this embodiment, the metal plate +93 is configured to be able to come into contact with and separate from the center conductor +4).

That is, (141 is an imaginary body, and this oscillating body (14
2) The metal plate (9) is in contact with and separated from the center conductor +4). In addition, in this example, gold III plate (
When 9J is in contact with or close to the center conductor f4j, the microwave is reflected at that part and
When +43 is apart, the microwave will be reflected at the short circuit (8) of the four microstrip circuits (1). The microwave behaves in a manner similar to that of the previous embodiment.

As mentioned above, in the present invention, since the conductive member is brought into contact with or close to the conductor on the side where the ladder pattern is not formed, and where the concentration of the electric field is rough, there is little risk of wing baking. Therefore, high-power microwaves can be supplied to the microslap line.

In addition, since there is no flange on the surface on which the ladder pattern is formed to prevent the object from being scanned, the effective surface sI of the microstrap 41 that contributes to heating is smaller than the conventional example (
increases compared to

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a state in which heating is caused by standing waves in a conventional example, Fig. 2 is a waveform diagram showing a state in which standing waves occur, Fig. 5 is a tanning diagram, and Fig. 7 is an embodiment of the present invention. An example is shown, Figure 5 is a perspective view, Figure 4 is a partial view of the main part, Figure 5 is a back view of the main part, Figures 6 and 7 are heating distribution. FIGS. 8 and 9 are schematic diagrams showing other embodiments of the present invention, and FIG.
The figure is a back view showing the main parts. (11... Microslip line, (2)... Dielectric jl & plate, (3)... Ground conductor, (4k/center conductor, (5)... Slit, [6J... Ladder pattern, (7) - coaxial cable, (81 - short circuit plate, (9)
...metal plate, scream--motor, ■...l! Heck. Applicant Sanyo Electric Co., Ltd. Figure 6 Figure 7 Figure 9 1 92 (// ) (( =4:

Claims (1)

[Claims] t A microstrap line in which a plurality of slits are opened along the propagation direction of microwaves in one conductor to form a ladder pattern, and a means for supplying microwaves to the microstrap line. and a means for scanning the object to be heated on the ladder pattern; A microwave heating device characterized by having a means for changing impedance. 2. The microwave heating device according to claim 1, wherein the means for changing the characteristic impedance of the microstrip line is a conductive member that intermittently approaches or contacts the conductor on which no ladder pattern is formed. (v) The means for reducing the characteristic impedance of the microstrip 4 is a non-circular electrically conductive member that can be rotatably viewed in close proximity to or in contact with the ladder pattern conductor. Microwave heating equipment as described in item 1 of the scope. Table Claim III in which the portion of the conductor where the conductive member contacts or approaches is narrower than other portions! 11th
Micro #I according to any one of item 111 and item 185 i
L heating device. (v) The microwave heating device according to any one of claims 1 to 4, wherein the fiber conductor is short-circuited at the end of the mist facing the microwave supply side. 6 The distance from the end opposite to the microphone CI wave supply to the part where the conductive member contacts or approaches is -1), -stomach λ・n/2+λ/4 (where λ is micro The effective wavelength within the wave microstrip 41 path, n is 0
A microwave heating device according to any one of claims 1 to 5, wherein the microwave heating device has a relation to it (an integer including 1).