JPS5819005B2 - Temperature probe for microwave oven - Google Patents

Description

Detailed Description of the Invention The present invention provides a microwave oven in which a plug connected via a cable to a detection part with a built-in temperature detection element that detects the temperature of an object to be heated is removably attached to a jack provided on the oven wall. For improving temperature probes.

Related.

2. Description of the Related Art Microwave ovens equipped with a temperature control device that detect the temperature of an object to be heated inside the oven using a temperature probe and terminate microwave heating when the temperature reaches a predetermined temperature are well known.

Therefore, there are many proposals for improving temperature probes, but the plug, which is connected via a cable to the detection part with a built-in temperature detection element that detects the temperature of the heated object, can be freely attached to and detached from a jack installed on the oven wall. The following improvements have not been made regarding the structure of the temperature probe that is attached to the

In other words, in the case of heating work that does not require a temperature probe, it is preferable to take the temperature probe out of the oven chamber.Therefore, a jack is installed on the oven wall so that it can be attached or detached using a plug. It is fine as long as you unplug it from the jack, but if you forget the temperature probe in the oven and heat it with microwaves, the microwaves will enter from the plug side and cause the temperature detection element to be exposed to the microwaves. A wave current is passed through it, causing abnormal heating, which can lead to destruction or deterioration of characteristics.

The structure of a conventional detachable temperature probe is roughly as shown in FIG.

According to this, 1 is a temperature detection element such as a thermistor, which is built in a protection tube 2 made of stainless steel and detects the temperature by inserting the protection tube 2 into a heated object, and the protection tube 2 is a temperature detection element. 1 and electrically coupled to one terminal of the coaxial cable 3.

This cable 3 consists of a core wire 3a and a braided wire 3b, and is connected to the sleeve 4a and tip 4b of the plug 4, respectively.
The above constitutes the signal transmission path of the temperature detection element 1.

The plug 4 is filled with an insulating material 4c, and the sleeve 4a and tip 4b are coaxially assembled.

When the temperature probe is configured in this way, depending on the size of the distance L between the tip 4b of the plug 4 and the sleeve 4a, it becomes a good antenna for the microwaves that are supplied to the inside of the oven. Microwaves enter the temperature detection element 1.

In view of this point, the present invention provides a temperature probe for a microwave oven that is improved so as to prevent microwaves from entering through the plug portion, thereby preventing destruction or characteristic deterioration of the temperature detection element.

FIG. 2 is a sectional view showing a plug 5 assembled into the temperature probe of the present invention, which is connected to the same cable 3 as in FIG. 1 and electrically connected to the temperature detection element 1.

Unlike the plug 4 in FIG. 1, this plug 5 has a sleeve 5.
A folded inner cylinder 5aa having a length of about λ/4 (λ is the wavelength inside the plug) is provided at a to form a double-tube sleeve,
It is filled with an insulating material 5c and connected to the core wire 3a1 of the cable 3 in a coaxial configuration with the chip 5b and the braided wire 3b, respectively.

When the plug 5 is configured in this way, the distance between the unshielded tip of the sleeve 5a and the tip of the tip 5b is, for example, L=λ
/4, the microwave is most strongly induced using this part as an antenna and is transmitted to the temperature detection element 1 via the cable 3.
Microwaves try to enter the side.

However, the impedance at point A becomes zero due to the choke effect of the sleeve 5a and the inner cylinder 5aa, and the microwave does not enter the cable 3 from this point A.

Therefore, the temperature detection element 1 built into the tip of the protection tube 2 is protected from the influence of microwaves.

FIG. 3 is a sectional view of a plug 6 assembled in another embodiment of the present invention, according to which the plug 6 is attached to the sleeve 6a about λ.
An inner cylinder 6aa having a length of /4 (λ is the wavelength within the plug) and opening at the tip side of the sleeve 6a is provided to form a double cylinder sleeve, and is filled with an insulating material 6c to form a coaxial structure with the chip 6b. , the core wire 3a of the cable 3 as shown in FIG.
It is connected to each of the knitting wires 3b.

When the plug 6 is configured in this way, the distance between the unshielded tip of the sleeve 6a and the tip of the tip 6b is, for example, L-λ.
/4, the microwave is most strongly induced using this part as an antenna and is transmitted to the temperature detection element 1 via the cable 3.
Microwaves try to enter the side, but the impedance at point A becomes zero due to the choke effect of the sleeve 6a and inner cylinder 5aa, so the temperature detection element 1 is protected from the microwaves as in the example shown in Fig. 2. .

As yet another embodiment, FIG. 4 shows a sectional view of another plug T.

According to this, the plug 7 is constructed by changing the diameter (thickness) of the core rod of the tip 7b, which is coaxial with the sleeve 7a, in the longitudinal direction such as bl and b2, so that the sleeve 7a is filled with the insulating material 7c. The distance between the tip Ib and the tip Ib is changed in the longitudinal direction, and the plug knob 7d is the base of the plug 7.
The inner diameter of the sleeve 7a and the inner diameter of the sleeve 7a are also changed in the longitudinal direction like al, C2, C3, C2D, E,
The impedance seen from the microwave entering direction at point F is changed.

Therefore, the microwaves that enter the coaxial cable 3 due to mismatching due to this difference in impedance are repeatedly reflected and lost, and the microwaves reach the temperature detection element 1 built in the tip of the protection tube 2. The energy is greatly attenuated and is more protected than microwaves.

Furthermore, according to experiments, if the distance between the sleeve tip and the tip tip is less than 5 mm, the antenna effect will almost disappear.
Microwaves are prevented from entering through this part.

As explained above, the present invention provides a temperature probe in which a plug connected via a cable to a detection part with a built-in temperature detection element that detects the temperature of an object to be heated is detachably attached to a jack provided on an oven wall. In this case, the above-mentioned plug connects the cable with a coaxial configuration of sleeve and tip, and since a λ/4 length choke is provided on the sleeve, the plug can be pulled out from the jack on the oven wall and the temperature probe can be left in the oven. Even if the temperature detection element is exposed to microwaves, the temperature detection element is protected from microwaves and will not be destroyed or suffer from characteristic deterioration, and can be put to practical use as a temperature probe with safety measures.

Further, if the plug is constructed by appropriately combining the above-mentioned embodiments, even more thorough safety measures can be taken.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional temperature probe for a microwave oven, and FIGS. 2 to 4 are sectional views of a plug assembled into the temperature probe for a microwave oven of the present invention. 1... Temperature detection element (thermistor), 2... Protection tube, 3... Cable, 4... Conventional plug, 5, 6.
7... Plug according to the present invention, 5 a 26 a 27
a... Sleeve, 5b t 6b, 7b... Chip.

Claims (1)

[Scope of Claims] 1. A temperature probe in which a plug connected via a cable to a detection part with a built-in temperature detection element for detecting the temperature of an object to be heated is removably attached to a jack provided on an oven wall. This is a temperature probe for microwave ovens that connects to a cable as a coaxial configuration of three nibs and a tip, and is characterized by having a λ/4 length choke installed in the sleeve. 2. A temperature probe for a patented microwave oven characterized by changing the gap between the sleeve and the tip in the direction of microwave penetration to prevent microwave penetration. 3. The temperature probe for a microwave oven according to claim 1, wherein the length between the tip end and the sleeve end is 5 mm or less.