JPS6214061B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a microwave oven with a heater that has a heater heating function in addition to a microwave heating function. Microwave ovens perform dielectric heating by irradiating the food with microwaves, so it is possible to generate heat over almost the entire food. However, unlike in the case of radiant heating, the surface area is not heated, so it is difficult to focus on the food. I can't attach it. In this way, the food surface does not get browned.
This has been a major problem with microwave ovens, as it can be inferior to conventional cooking methods in terms of appearance, flavor, etc., depending on the type of food being cooked. In order to compensate for the above-mentioned drawbacks of microwave heating, devices have been developed in which a radiant heater, such as an electric heater, a gas combustion heater, or an infrared heater, is provided in the oven, which is the heating chamber. However, even in an apparatus equipped with such a radiant heater, it is difficult to achieve an appropriate degree of focus depending on the type of food, and it is also not possible to achieve a uniform degree of focus. In response to this, the applicant installed an infrared radiation type so-called browner heater in the oven, supported it so that it could move up and down in the oven, and made it possible to adjust the distance between the food surface and the heater surface by external operation. Special request for a microwave oven with a heater was made in 1974.
An application has already been filed under No. 59028. The first object of the present invention is to improve the above-mentioned microwave oven with a heater, in which the Brauner heater is moved up and down by a manual lever.
The heater is automated by a drive means such as a motor, and the second purpose is to be able to detect when the heater hits the food while it is moving.The third purpose is to configure the detection means with an electronic circuit. The fourth purpose is to return the heater to its initial position when it hits food. In order to achieve the above-mentioned object, the present invention is equipped with a heater built in an oven, which is a heating chamber, which is movably transported by a driving means such as a motor, and which can be stopped and held at a proper position in the oven. in the microwave oven, a counting means for counting up a time pulse during transportation of the heater; and an abnormality detection signal outputting means for outputting an abnormality detection signal when the time measured by counting up by the counting means exceeds a predetermined time. The apparatus further comprises a return operation means for returning the driving means to the return operation based on the output of the abnormality detection signal output means. An embodiment of the heater-equipped microwave oven of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the external appearance of a microwave oven with a heater, which is an embodiment of the present invention. A turntable 2 is provided at the inner bottom of the oven 1, which is a heating chamber, and a browner heater, which will be described later, is provided at the top. 3 is provided. An operation panel 5 is provided on the front surface of the main body along with a door 4 that can freely open and close the opening of the oven 1, and a keyboard 6 and a digital display device 7 are provided with keys to be described later. This heater-equipped microwave oven is equipped with a microcomputer in the control circuit section, and by operating each key arranged on the keyboard 6, a cooking program suitable for the type of food can be created. The key layout is, for example, as shown in FIG. Here, 60a is a key group consisting of keys for selecting and setting the heating method, for example.

[Formula] The key is the key to set microwave output 30% as low heat,

[Formula] The key is microwave output as a high flame. Key to set power 100%,

[Formula] The key is the key to operate the Brauner heater 3,

The [Formula] key is a key for instructing to which position in the oven the heater 3 is to be moved. In addition, 60b is a key group consisting of a numeric keypad for setting numerical information such as cooking time and heater position, and 60c is a key group for starting cooking (

[Formula] key) or stop (

[Formula] key) is a set of keys. Now, as an example, a cooking program to be set up when cooking frozen meat for steak will be explained. This cooking program consists of the following three steps. First stage: As a thawing process, heat repeatedly for 4 minutes at 30% microwave output. 2nd stage Microwave output for normal cooking work
Heat to 100% over high heat for 2 minutes and 30 seconds. 3rd Stage As a browner browner heater, move the heater to heater position "3" in the oven and heat it for 7 minutes. In the process of focusing, the position of the browner heater in the oven may be selected to suit the user's preference. In order to automatically switch between such three-stage cooking sequences, each key is selected and operated in advance as follows.

[Table] Ji starts cooking.
FIG. 3 is an internal configuration diagram of the heater-equipped microwave oven shown in FIG. 1, viewed from the front, and mainly shows the vertical drive and support mechanism of the Brauner heater 3. A magnetron (not shown) is installed outside the oven 1, which is the cooking chamber, and when it is in operation, it projects 2450MHz microwaves into the oven 1, while when the heater 3 is in operation, it directs the radiant heat onto the turntable 2. irradiate the food to bring it into focus. The turntable 2 is located at the bottom of the oven and is rotatably supported at its center bottom.
It rotates by being connected to the drive shaft of an externally mounted motor 8. As the turntable 2 rotates, the relative position of the food in the oven changes, making not only the microwave irradiation conditions but also the radiant heat irradiation conditions from the heater 3 almost uniform regardless of the location of the food, thereby eliminating uneven heating. You can cook food without any food. The heater 3 consists of a back plate 31 and a meandering heat generating part 32 located on the back plate 31. The back plate 31 has a surface facing the heat generating part 32 made of a mirror-finished metal plate or a heat-resistant ceramic plate. The radiant heat radiated toward the oven ceiling is reflected toward the food. The heat generating section 32 of the heater 3 is made of a sheathed heater, and a heat generating resistance wire that generates heat when energized is inserted into the interior of a highly conductive tubular sheath. A heat-resistant insulating material such as magnesia is filled between the tubular sheath and the resistance wire. Further, the heat generating portions 32 meander in order to increase the heat generating area on the surface facing the back plate 31, and are fixed to each other by fixtures 33 on both side walls of the back plate 31. In heater 3,
The sheathed heater covering the heat generating resistance wire extends further from the attachment end of the back plate 31 and is provided in a long integral manner, penetrating both side walls of the oven and forming a support pipe 34 that supports the heater 3. . A lead wire is inserted through the support pipe 34, and an electrical connection is made to the resistance wire near where the support pipe 34 passes through the side wall of the back plate 31 to connect the heater 3 to a power supply circuit located outside the oven. electrically connected. Note that the support pipe 34 can be formed integrally with the sheath of the heat generating part 32 from a conductor, but in consideration of the process of assembling the microwave oven, the sheath of the heat generating part and the support pipe made of a conductor may be formed separately. Consisting of
Electrical connections may be made using coupling means such as joints. Further, since the lead wires inserted into the support pipe 34 are covered with a pipe made of a conductive material, there is no fear that the microwaves projected into the oven will ride on the lead wires and leak to the outside of the oven. The oven side wall where the support pipes 34, 34 on both sides are located is provided with a recess 9 that protrudes outward to avoid a reduction in the volume inside the oven. has been derived. A cylindrical radio wave shielding means 11 having a chiyoke structure is attached to the bottom wall 10 in order to shield microwaves from leaking to the outside from the penetrating portion of the support pipe 34. A vertical movement driving and supporting mechanism for the heater 3 as shown in FIGS. 3 to 5 is provided outside the oven 1. First, L-shaped support plates 12, 12 are attached to both sides of the top plate 101 of the oven 1, which rotatably supports a shaft 14 to which pulleys 13, 13 are fixed at both ends, and the other side forms the outer casing of the microwave oven. L-shaped support plates 16, 16 are attached to both sides of the bottom plate 150 of the cabinet 15, and pulleys 18, 18, which are rotatable with shafts 17, 17, are mounted on the L-shaped support plates 16, 16.
Timing belts 19, 19 supporting the upper and lower pulleys 13, 18 are suspended. A transmission gear 22 is fixed to the right end of the shaft 14, and a drive gear 2 is rotationally driven by a motor 20.
1 and rotation is transmitted. Furthermore, motor 2
0 is attached to the top plate 101 of the oven 1 with a support plate 23. Furthermore, as shown in an enlarged view in FIG. 5, a belt fixing fitting 25 is attached to the timing belt 19.
However, the heater fixing fittings 26 are attached to the support pipe 34 of the heater 3 with screws 24 and 28, respectively, and both fittings 25 and 26 are connected by a spring 27. The spring 27 has one end attached to the belt fixing fitting 25 and the other end attached to a fixing piece 260 bent and raised from the heater fixing fitting 26, and normally transmits the movement of the belt 19 to the heater 3 by its tensile force.
The structure is such that the two move together as one.
If the heater 3 hits food or tableware placed on the turntable 2 during its descent, the heater 3 will stop at that position, but the belt 19 will be further driven by the motor 20 until the heater fixing bracket 26 Broken line 2 relative to the fixed piece 260 of
The belt fixing fitting 25, which was at the position 5', is lowered to the position shown by the solid line in FIG. 5 against the tensile force of the spring 27. Accordingly, the actuator of the food detection switch 29 is pressed and the food detection switch 29 is closed. This food detection switch 29 is attached to the heater fixture 26 and is assembled as a means for reversing the motor 20 in conjunction with its closing operation, as will be described later. Attached to the left side of the heater fixture 26 is a switch operation plate 40 having three vertical rows of protrusions 40a to 40h formed on one surface thereof. As shown in a perspective view in FIG. 6 and in a side view in FIG. The actuators face the switches 42, 43, and 44, and the protrusions in each row are positioned on the respective actuators, with the switch 42 in the first row, the switch 43 in the second row, and the switch 44 in the third row.
The protrusions 40a to 40d in the first row are treated as position marks, and the protrusions 40e to 40h in the second and third columns are treated as sensing marks. The switches 43 and 44 facing the protrusions in the second and third rows operate as sensing mark read switches, and the sensing marks are formed longer than the position marks. This is to ensure that the position mark read switch 42 operates after the sensing mark read switches 43 and 44 operate reliably. These switches 42 to 44 are food detection switches 2
9 and is assembled into the electric circuit shown in FIG. 9, which will be described later. FIG. 8 shows an electric circuit installed in the above-mentioned microwave oven with heater. According to this, the control circuit 50
(shown by dashed-dotted lines), five relays RL ₁ to RL ₅ that suitably connect power to each load, and the above-mentioned key group 60
A keyboard 6 with a to 60c array, and a display device 7
A microcomputer 51 is also installed which stores a cooking program input through key operations on the keyboard 6 and executes cooking according to the program. Amplifiers 52 to 56 that drive relays RL ₁ to RL ₅ are connected to this microcomputer 51 . Further, 57 is a constant voltage power supply that supplies DC voltage to each device of the control circuit section 50. Relay RL ₁ opens and closes switch 61 and operates fan motor 6 that rotates the magnetron cooling fan.
The relay RL ₂ opens and closes the switch 64 to control the energization of the high voltage generating circuit 63 and causes the magnetron 62 to output microwaves. Relay RL ₃ opens and closes switch 65 to control energization of the Brauner heater 3 described above, and relay RL ₄ opens and closes switch 66 to control energization of motor 20 that moves heater 3 up and down. When the other relay RL ₅ is activated, it switches the heater vertical movement changeover switch 67, which is connected in series with the previous switch 66 and is normally at the normally closed contact NC, to the normally open contact NO. The motor 20 is rotated in the reverse direction by switching the heater vertical movement changeover switch 67. Now, a vertical movement control circuit for the heater 3 shown in FIG. 9 is installed in the microcomputer 51. Schematically, among the keys arranged on the keyboard 6 shown in FIG. 2, the key for specifying the heater position is

[Formula] key After operating the number keys, e.g.

[Formula] By operating the key, the stop position of the heater 3 can be stored in advance. and

[Formula] When cooking is started in response to key operation, the heater 3 is controlled to be automatically moved to the set heater position "4" in synchronization with the heating operation. According to FIG. 9, 6 indicates a keyboard provided on the operation panel 5 shown in FIG. 2, including a key group 60a for setting the heating method and a key group 60b for setting numerical information such as cooking time and heater position. As described above, it is comprised of the key group 60c for setting the start or stop of cooking. The output of each key is code-converted by an encoder 70 into a code signal consisting of binary signals "0" and "1" handled by a microcomputer, and sent to a central processing unit (CPU) 71. Here, the key group 60b
Number keys arranged in a numeric keypad configuration

Numerical information on the cooking time and heater position input by operating [Formula] is transferred to the storage device (RAM) 73 and stored there. In addition, the key group 60c

[Formula] When the key is operated, a cooking start signal S is generated from the central processing unit (CPU) 71. According to the cooking example of frozen meat for steak mentioned above,
Numerical information on the cooking time and heater position for each stage is stored in the storage device (RAM) 73 in accordance with key operations according to the procedure, and as the cooking start signal is generated, the cooking time information is sequentially stored in the counter 74 and the numerical information on the heater position is stored in the storage device (RAM) 73. The information is transferred to temporary storage registers 75, respectively. Set the cooking program,

[Formula] When the key is operated, a cooking start signal is generated, and the thawing operation, which is the first step, is started. At this stage, microcomputer 51 generates a signal to drive relay RL ₂ intermittently with a duty of 3/10 based on a control command read from fixed storage device (ROM) 72. Therefore, the high pressure generating circuit 63 is driven intermittently to cause the magnetron 62 to oscillate 30% of the microwave output, thereby performing carryover heating suitable for thawing the frozen food. At this time, the relay
RL ₁ operates simultaneously to rotate the turntable 2 and rotate the magnetron cooling fan.
Further, the digital display device 7 sequentially counts down the set cooking (defrosting) time by four minutes. When this display reaches zero, the process moves to the second step. Microcomputer 51 outputs a signal to continuously operate relay RL ₂ based on the second stage control command read from fixed storage device (ROM) 72 . Therefore, in this stage, high flame heating with 100% microwave output is performed. fan motor 6
0, the turntable 8 remains in operation, and the display device 7 sequentially counts down the set cooking time of 2 minutes and 30 seconds.
When this display reaches zero, the process moves to the third and final focusing step. Since this focusing process is related to the gist of the invention, it will be explained in detail with reference to FIG. That is, when the second stage process is completed, the storage device (RAM) 7
3, the cooking (scorching) time information is transferred to the counter 74 as in the previous stage,
On the other hand, heater position information is transferred to temporary storage register 75. At the same time, a heater drive instruction signal is generated from the central processing unit (CPU) 71 to set the flip-flop 89. This setting causes the Q terminal of flip-flop 89 to go high,
Amplifier 54 is operated to close switch 65 by relay RL ₃ . The browner heater 3 starts to be energized by this, and projects radiant heat onto the food from its heat generating part 32, but at the same time, the browner heater 3 is moved to the heater position "3" in the oven 1, which has been programmed in advance in the cooking program. work has begun. The heater position "3" is encoded by the encoder 70 as a code signal 110 as shown in Table 1, and is temporarily stored in the register 75. However, due to the generation of the heater drive instruction signal, three
MOS transistors 76 to 78 are turned on and the signal is transferred to register 79.

[Table] In Table 1, “1” indicates the switch is closed.
"0" corresponds to the open state of the switch. Therefore, for example, when the heater is in position "2", the switch 42 is closed, the switch 43 is open, and the switch 42 is closed.
4 is in a closed state. The register 80 is a device that stores heater position information corresponding to the actual position of the heater 3. The heater 3 is always located at the uppermost stage in the oven 1 (near the top plate 101) as an initial position, and this corresponds to heater position "1". Therefore, register 80
A code signal 100 corresponding to heater position "1" is stored in advance. Here, since the code signal is set and input to the register 80 through the switches 42 to 44 shown in FIG. 6, the heater position "1" means that the switch operation plate 40 is at the top of its vertical movement range. only the actuator of the switch 42 is located on the protrusion 40.
It is closed by being pressed by d. The switch operation panel 40 in FIG. 6 has heater positions "1" to "1" on the right end
A number is written in the place corresponding to "4". A comparator 81 connects both registers 79 and 80, compares the magnitude of the code signals stored in both, and keeps the A>B terminal in a high state until they match.
Assuming that the code signal stored in register 71 is A and the code signal stored in register 80 is B,
When the heater drive instruction signal is generated and the third stage process is started, A>B, so the comparator 81 sets the A>B terminal to a high state and outputs a signal to the amplifier 55 via the OR gate 82. do. Relay RL ₄ is operated in accordance with this, and since it is a relay that operates motor 20 as shown in FIG. 8, heater 3 begins to descend. Since the lowering of the heater 3 is accompanied by the lowering of the switch operation plate 40 at the same time, the protrusions 40a to 40h selectively open and close the switches 42 to 44 in sequence. That is, the register 80 contains code signals 101, 110, and 110 corresponding to each heater position.
111 are input in sequence. When the heater reaches position "3" while the heater is lowering, a code signal of 110 is input to the register 80, so the comparator 81 detects A=B and outputs the A>B terminal.
Invert to Low state. This causes the relay RL ₄ to be disconnected, and the heater 3 therefore stops descending and is held in that position for 7 minutes to brown the food. However, the heater 3 may hit food or tableware during its descent. Of course, this does not always happen, and if you happen to lower the heater to the intended position, the food may be larger than expected. In that case, as explained in FIG. 5, the heater 3 and the switch operation plate 40 stop at the position where they hit the food due to the expansion of the spring 27, but the belt 19 moves until the food detection switch 29 is closed. continue. Switch 29 assembled in FIG. 9 represents this food detection switch, and when it is closed, it resets flip-flops 84 and 85 via OR gate 83. Accordingly, the contents of the lower two bits of the register 79 are forcibly set to "0", and the code signal is switched to the code signal 100. That is,
When A>B hit the food, it changes to A<B, and the comparator 81 immediately sets the A<B terminal to a high state and sends the relays RL ₄ and RL ₅ to return the heater 3 to the top stage. Activate. As described above, the relay RL ₅ is a relay that switches the heater vertical movement changeover switch 67 to the normally open contact NO and rotates the motor 20 in the reverse direction. When the heater 3 returns to the top stage, which is the heater position "1", only the switch 42 is closed and the register 80 receives the code signal 1.
00 is input. As a result, the comparator 81 outputs A=
Detect B and invert the A<B terminal to Low state,
Disconnect relays RL ₄ and RL ₅ . Further, when the food detection switch 29 is closed, the flip-flop 86 is reset and the counter 74 is reset.
Force the contents of to zero. Accordingly, the zero detection circuit 87 resets the flip-flop 89. Therefore, relay RL ₃ is cut off and heater 3
Cut off the electricity. At this time, the notification circuit 5 shown in FIG.
8 to notify the error. The user must therefore reset the heater position and try again.

[Formula] key must be operated. Indeed, by incorporating the food detection switch 29 into the vertical drive mechanism of the browner heater 3, it is possible to detect when the browner heater 3 hits the food. However, since it is mechanically configured, springs 27, belt fixing fittings 25, etc. are required, which inevitably increases the number of parts and the assembly process, and furthermore, the desired elastic force is lost due to the life of the springs 27. It has the disadvantage that accurate food detection is not possible. Therefore, in the present invention, without using such parts,
Therefore, the food detection switch 29 and the OR gate 83 are omitted from the control circuit section of FIG. 9, and an electronic circuit such as a counter 90 is used instead. Of course, the electronic circuit is assembled into the microcomputer 51. Further, the belt fixing fitting 25 before the improvement is unnecessary, and the belt 19 is directly connected to the heater fixing fitting 26. The improved vertical movement control circuit of the heater 3 is installed in the 10th
As shown in the figure. In this figure, the same parts with the same reference numerals as in Fig. 9 are used, and therefore, the explanation of the parts common to Fig. 9 has already been explained, so here we will explain the newly assembled circuit parts. Explain. According to this, 91 is an AND gate, and the connection point between the switch 42 and the register 80, and the comparator 8.
Connect the A>B terminals of 1 to the respective input terminals,
The output terminal is connected to the reset circuit 92. Therefore, the function of this AND gate 91 is that the comparator 8
When the A>B terminal of 1 is in the High state and the position mark reading switch 42 is in the closed state, an output is sent to the reset circuit 92, and the counter 90 is reset by the reset pulse output from the reset circuit 92. It is something that makes you 93
is another AND gate, the output terminal of the count control circuit 88 and the A>B terminal of the comparator 81 are connected to their respective input terminals, and the output terminal is connected to the counter 90. As will be described later, the count control circuit 88 is a timing pulse generation means that counts the power supply frequency of 60 Hz and periodically outputs a pulse at a rate of one per second. A>B terminal
When in the High state, a timing pulse is output to the counter 90, and thereby the counter 90 sequentially counts up each time the timing pulse is input. 9
4 is an overflow detection circuit which detects when the count of the counter 90 exceeds a predetermined value and outputs an abnormality detection signal p to the reset terminal of the flip-flop 89. flip flop 89
is reset in response to the generation of the abnormality detection signal p, and accordingly, the relay RL ₃ is immediately disconnected and the energization of the Brauner heater 3 is stopped. On the other hand, at this time, the terminal of flip-flop 89 is switched to a high state, so flip-flops 84 and 85 are reset, and the contents of register 79 are forcibly set to "100". By the way, when the Brauner heater 3 enters the focusing work process and the work to move the heater 3 to the programmed predetermined heater position starts, a timing pulse is output from the AND gate 93, and the counter 90 starts counting up. Start operation.
However, each time the switch 42 is closed while the heater 3 is lowering, the count contents of the counter 90 are reset by a reset pulse output from the reset circuit 92, and the counter 90 starts counting up again in synchronization with the opening of the switch 42. Let's do it. As described above, in the case where the food is programmed to be moved to the heater position "3", it is assumed that the heater 3 hits the food just before it descends to the heater position "3" and reaches the heater position "3". Note that the time required for the heater 3 to move between each heater position is 8 seconds. In this case, when the heater 3 passes the heater position "2", the counter 90 starts counting up again from zero, but because it hits the food on the way, the switch does not start even after 8 seconds have passed after passing the heater position "2". 42 is not closed. Therefore, the reset circuit 92 does not output a reset signal even after 8 seconds have passed, so the counter 90 is not reset even after 8 seconds, that is, 7 timing pulses have been input, and continues to count up. . The counter 90 has a 3-bit configuration, and when seven timing pulses are input, the count becomes "111". Therefore, if more clock pulses are input, the digits will overflow, or in other words, there will be an overflow.
The overflow detection circuit 94 detects this and outputs an abnormality detection signal p. Upon generation of the abnormality detection signal p, the flip-flop 89 is reset, the relay RL ₃ is immediately disconnected, and the energization of the pruner heater 3 is stopped. Then, since the terminal of flip-flop 89 is switched to the high state, flip-flops 84, 8
5 is forced to be reset to "0", and therefore register 79 is forced to be set to "100". This means that A>B, which had been A>B, is forcibly changed to A<B, and the A<B terminal of the comparator 81 is forcibly changed to the High state. Because of this, relays RL ₄ and RL ₅ are driven and the motor 20 is rotated in the reverse direction, causing the Brauner heater 3
is raised and returned to its initial position. If the browner heater 3 does not hit the food, or after hitting the food, adjusts the heater position one step higher and is brought to a predetermined heater position, the focusing operation is performed at that position for a preset time. . When the heater 3 is brought to the desired position and the focusing work is completed, the display device 7 reaches zero. Zero detection circuit 8
The output of 7 detects this and goes high, resetting the flip-flop 89. At this time, that terminal switches to High, so the flip-flop 8
4,85 and the contents of register 79.
Force set to 100. As a result, the comparator 81 immediately sets the A<B terminal to a high state and relays RL ₄ and RL ₅
Activate. Therefore, as mentioned above, register 8
The heater 3 is raised until the content of 0 reaches 100. Note that 88 is a count control circuit that counts the power supply frequency of 60 Hz and periodically outputs pulses at a rate of one per second to cause the counter 74 to count down. Further, a display body 7a provided at the left end of the display device 7 digitally displays the heater position. In this way, the predetermined cooking program ends. At this time, since the heater 3 is reset near the top plate 101 as the top shelf in the oven, there is little risk of the food being melted by the heater 3 when the food is taken out. Also, during microwave heating, uneven heating does not occur because it is on the top stage. Since the microwave oven with a heater of the present invention is as described above, the heater is automatically moved to an appropriate position in the oven that has been set in advance, and the desired browning can be achieved. There is no need to move the sensor, and the abnormality detection means can be implemented as an electronic circuit.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of a microwave oven with a heater according to the present invention. Figure 2 is an enlarged view of the operation panel. FIG. 3 is a front view showing the internal structure. Figure 4 is its side view. Figure 5 is an enlarged view of the main parts. FIG. 6 is an enlarged perspective view of the switch operation panel. Figure 7 is its side view. FIG. 8 is an electric circuit diagram assembled into the above-mentioned microwave oven with heater. FIG. 9 is an electric circuit diagram showing the control circuit section before the improvement. FIG. 10 is an electrical circuit diagram showing the improved control circuit section. 1...Oven, 3...Browner heater, 6...
Keyboard, 13, 17... Pulley, 19... Belt, 20... Motor, 40... Switch operation board, 42
~44...Switch, 51...Microcomputer,
90... Counter, 94... Overflow detection circuit, p... Abnormality detection signal.

Claims (1)

[Claims] 1. In a microwave oven equipped with a heater, in which a heater built into the oven, which is a heating chamber, is movably transported by a driving means such as a motor, and the heater can be stopped and held at a suitable position within the oven, the heater is transported while the heater is being transported. a counting means for counting up the time measurement pulse of the counting means; an abnormality detection signal outputting means for outputting an abnormality detection signal when the time measured by the counting up of the counting means exceeds a predetermined time; and an output of the abnormality detection signal outputting means. a return operation means for returning the drive means to an initial position.