CN1146703C

CN1146703C - Heating cooker

Info

Publication number: CN1146703C
Application number: CNB971229678A
Authority: CN
Inventors: 冈村嘉夫
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 1996-11-29
Filing date: 1997-11-28
Publication date: 2004-04-21
Anticipated expiration: 2017-11-28
Also published as: JPH10160167A; KR19980041900A; GB9725172D0; KR100312917B1; JP3288234B2; CN1184231A; MY123783A; TW349165B; GB2319910B; GB2319910A; GB9725477D0

Abstract

The door of a microwave oven is associated with at least two safety switches 24,25 connected in power supply lines 31,32 and operating in response to opening and closing of the door. A switch 29 is operated when the door is opened, and causes a microcomputer control circuit 35 to measure the resistance of a path A through the switches 24,25 to determine whether the switches are operating correctly. Visible and audible indications are provided for fault conditions such as welded switch contacts, broken wires, deterioration of primary transformer winding 34a, and poor condition of other oven components. The oven may also be disconnected from the power supply, or subsequent operation may be prevented.

Description

Heating device

Technical field

The present invention relates on power line, dispose the heating device that carries out the safety switch of switch motion according to the switching of door.

Background technology

Fig. 8 shows an example of the local circuit structure that has disposed safety switch in the micro-wave oven of this heating device.As shown in Figure 8, derive power line 2,3, in these power lines 2,3, dispose safety switch 4,5 respectively from the attaching plug 1 that is connected with industrial AC power.Safety switch 4 and 1 of attaching plug at power line 2 on one side are provided with fuse 6.

Also have, also away from being connected with pilot switch 7 on the power supply position on one side, also be connected with a winding 8a of transformer 8 simultaneously than the safety switch 4,5 of 2,3 of power lines.Above-mentioned safety switch 4,5 disconnects when opening, connects when closing.Pilot switch 7 is so-called short switches, connects when door is opened, and disconnects when door is closed.In addition, transformer 8 is the transformers that constitute the power circuit of magnetron supply power.

Under the situation of above-mentioned formation, break down and when continue connecting, if door is opened, pilot switch 7 is just connected, and therefore, has formed short circuit current, flows through overcurrent, fuse 4 fusing at safety switch 4,5.Like this, just become and to prevent under the state that safety switch 4,5 breaks down, to use microwave oven structure.

But, in above-mentioned existing structure, when fuse 4 fusing,, therefore, be not very good on safety though be always to have overcurrent to flow through the short time.Also have, when above-mentioned overcurrent flows through, the action of opening circuit of the breaker of distribution board.And, under the some situations about breaking down in two safety switches 4,5, owing to do not form short circuit current, so, just be created in the rough sledding of in the same old way using micro-wave oven under the state of a safety switch fault.

Further also have, need between the switch motion of the switch motion of two safety switches 4,5 and pilot switch 7, be set the time difference.Specifically, under the situation that door is opened, need pilot switch 7 after safety switch 4,5 is connected, to connect again, under the situation that door is closed, safety switch 4,5 is connected after pilot switch 7 disconnects again.Therefore just need be used to be provided with the special-purpose lever part of above-mentioned time difference, only this point shortcoming that the structure complicated of making just arranged and product cost is uprised.

In addition, Fig. 9 shows a kind of of structure that above-mentioned switch 4,5,7 is set in the main body of micro-wave oven.As shown in Figure 9, utilize the operating portion 10 that is located on the door 9 to make a safety switch 4 carry out switch motion, utilize the operating portion 11 and the interlock lever 12 that are located on the door 9 to make another safety switch 5 carry out switch motion.And pilot switch 7 utilizes the operating portion 11 of door 9 and is used to be provided with the special-purpose lever 13 of time difference and carries out switch motion.

Summary of the invention

Therefore, the object of the present invention is to provide such heating device: can prevent to flow through overcurrent when safety switch breaks down, any one that can judge two safety switches breaks down, and can seek simplified structure and reduce product cost.

According to a kind of heating device of the present invention, wherein, between the two poles of the earth of the power line of the primary side of the transformer that supplies power to described heating device from source power supply, safety switch is set, these safety switches respond described heating device heating clamber the door switching and move, it is characterized in that:

Described each safety switch is respectively a double-throw type switch,

The common junction of described each safety switch is connected with described transformer side respectively,

In the fixed contact of described each safety switch, respectively when described door is closed, be connected to source power supply side power line respectively by the reveal fixed contact that closes of closure,

Described heating device has:

In the fixed contact of the described safety switch of one side, when described door is opened, the ground connection circuit passband that is connected with the side fixed contact that opens the door by closure,

Among the fixed contact of the described safety switch of opposite side, when described door is closed, be connected, detect the switch checkout gear that described ground connection circuit passband has or not energising with the side fixed contact that opens the door by closure,

Detect described door open and-shut mode the door checkout gear and

When detecting described door by described door checkout gear and open, make described switch checkout gear detect the control device of action.

If employing said structure, owing to when door is opened, make the switch checkout gear detect action, so, when in two safety switches either party breaks down, open conducting state between side joint point by detecting gate, can judge that an above-mentioned side's safety switch breaks down.And, under the situation of this structure,, do not flow through overcurrent even safety switch breaks down yet.Also have, owing to can also save monitoring switch and save the bar of pilot switch special use simultaneously, so simple in structure, simultaneously, product cost is low.Also have, though also need the door checkout gear as the open and-shut mode of detecting gate such as door switch in addition, owing to also can make door switch and safety switch synchronously carry out switch motion, so the bar of pilot switch special use has not just needed.

Also have, under the situation of said structure, be preferably in the moment that door opens to make the switch checkout gear carry out the detection action of stipulated time.And then, also can be judged as unusual time notice by the switch checkout gear should be unusual and forbid adding the heat run action.

And then also have, two safety switches of switch checkout gear best detection leave resistance between side joint point at door, and simultaneously, when the magnitude of voltage that detects be infinity, fault had taken place in the judgement safety switch.At this moment, the switch checkout gear also can just be judged as second abnormality during greater than setting value in the resistance value that detects.Also have, also can during less than setting value, be judged as the 3rd abnormality in the resistance value that detects.

On the other hand, a plurality of loads are set between power line and make a plurality of relays of each load on/off, and the switch checkout gear is preferably by making a plurality of relays connect the fault of judging each load successively.When this structure, when in the state that door is being opened, making the operated key of operating screen carry out special operational, preferably make the switch checkout gear detect action.

Description of drawings

Fig. 1 is the circuit diagram that is used to illustrate the principle of the detection action of representing one embodiment of the present of invention;

Fig. 2 is the summary vertical profile side view of micro-wave oven;

Fig. 3 is the major part of expression control circuit and the circuit diagram of safety switch;

When Fig. 4 breaks down at a safety switch, the figure suitable with Fig. 1;

Fig. 5 is a flow chart;

Fig. 6 is the circuit diagram of the micro-wave oven of band heater;

Fig. 7 is a flow chart;

Fig. 8 represents to have earlier figure structure, suitable with Fig. 1;

Fig. 9 is the figure suitable with Fig. 2.

The specific embodiment

Below, an embodiment who applies the present invention to micro-wave oven is described referring to figs. 1 through Fig. 7.The fault detect principle of the safety switch of present embodiment at first, is described according to Fig. 1 to Fig. 5.Fig. 2 is the figure of schematic configuration around the safety switch in the Machine Room of expression micro-wave oven.Among Fig. 2, the front openings portion that is located at the heating clamber (not shown) in the micro-wave oven main body 21 utilizes door 22 to open and close.And, in main body 21, be provided with the Machine Room 23 with above-mentioned heating clamber adjacency, in Machine Room 23, be provided with two

safety switches

24 and 25.

These safety switches 24,25 for example are made of micro switch.One of them (top) safety switch 24 utilizes the operating portion 26 on the top, end that is located at door 22 to carry out switch motion.In addition, another (bottom) safety switch 25 utilize the bottom, end that is located at door 22 operating portion 27, carry out switch motion by trace 28.

And shown in the circuit diagram of Fig. 1,

safety switch

24,25 has common junction C and two contact a and b, constitutes: when door 22 is closed, connect between contact (c-a); When door 22 is opened, connect between contact (c-b).At this moment, each contact b formation door of

full switch

24,25 to open the side joint point.

Also have, near the safety switch 25 of bottom, be provided with door switch 29 (not shown among Fig. 2, shown in Figure 1), and laterally be arranged side by side with this safety switch 25.This door switch for example is made of micro switch, and utilize door 22 operating portion 27, carry out switch motion by trace 28, promptly carry out switch motion synchronously with safety switch 25.And door switch 29 is for example connected when door 22 is closed, is disconnected when door 22 is opened.Like this, just can utilize the on/off of door switch 29, the open and-shut mode of detecting gate 22.At this moment, door switch 29 constitutes the door checkout gear.Also have, it is opposite with above-mentioned on/off action that door switch 29 also can constitute the on/off action that door 22 is opened and closed.

In Fig. 1 of expression electrical structure, derive

power line

31,32 from the supply socket 30 that links to each other with industrial AC power, be provided with fuse 33 and safety switch 24 on the power line 31 of a side in these

power lines

31,32, simultaneously, on the opposing party's power line 32, be provided with safety switch 25.And, be connected with a winding 34a of transformer 34 31,32 of power lines.

Specifically, the contact a of safety switch 24 links to each other with an end of fuse 33, and common junction c links to each other with the end of a winding 34a.And the contact a of safety switch 25 links to each other with supply socket 30, and common junction c links to each other with the other end of a winding 34a.Like this, but

safety switch

24,25 constitutes the structure at the two poles of the earth of

deenergization line

31,32 respectively.In addition, the contact b of safety switch 24 links to each other with the first terminal 36 of control circuit 35, and the contact b of safety switch 25 links to each other with second terminal 37 of control circuit 35.Also have, two contact c of door switch 29 link to each other with the 3rd terminal 3 and the 4th terminal 39 of control circuit 35 with a.

On the other hand, transformer 34 is to constitute to magnetron (not shown) to supply with the transformer that drives with the current circuit of power supply, is connecting main relay and constitute the various electric components (and then magnetron) of the power circuit that driven by magnetron uses on its secondary winding 34b.

Moreover above-mentioned control circuit 35 has each function as switch checkout gear of the present invention and control device.And as shown in Figure 3, control device 35 is made of microcomputer of installing on printed circuit board 40 (calling microcomputer in the following text) 41 and various electronic unit.Above-mentioned microcomputer has all functions of running of control micro-wave oven, is storing the control program that is used for above-mentioned control.Also have, as shown in Figure 1, supply with from the constant voltage (for example DC voltage of 5V) of DC power supply circuit 42 outputs to control circuit 35.This DC power supply circuit 42 is connected the part between the contact a of part between the contact a of fuse 33 in the power line 31 and safety switch 24 and supply socket 30 in the power line 32 and safety switch 25.

Then, with reference to Fig. 3 the structure that detects unusual (fault) of

safety switch

24,25 with microcomputer 41 is described.As shown in Figure 3, the contact b of safety switch 24 links to each other with the input 41a of microcomputer 41 by resistance 43, simultaneously, links to each other with the output 41b of microcomputer 41 by resistance 44, and then the conductor that is used for ground connection that is provided with on the electric capacity 45 of eliminating usefulness by noise and the printed circuit board 40 links to each other and ground connection.And the contact b of safety switch 25 links to each other and ground connection with the conductor that is used for ground connection that is provided with on printed circuit board 40.

Under the situation of this structure, microcomputer 41 is from lead-out terminal 41b output dc constant voltage (for example DC voltage of 5V), simultaneously the analog voltage signal that is input to input terminal 41a is carried out the A/D conversion, input through the A/D conversion digital voltage signal, carry out signal and handle (for example judging the processing of magnitude of voltage).

And, in said structure, under the state of the door 22 of opening micro-wave oven, connect between safety switch 24 and each contact (c-b) of 25, as Fig. 3 and shown in Figure 1, formed from the lead-out terminal 41b of microcomputer 41 through between the contact (c-b) of resistance 44, safety switch 24, flow to the electrical path on ground between the contact (c-b) of a winding 34a of transformer 34, safety switch 25.

Under the state that has formed this electrical path, the DC voltage that provides from the lead-out terminal 41b of microcomputer 41 is by resistance 44, through the energising electric resistance partial pressure of the energising path between the contact (c-b) of safety switch 24, between the contact (c-b) of winding of transformer 34 and safety switch 25.And, the voltage signal of dividing potential drop is offered input terminal 41a.Therefore, microcomputer 41 can utilize the voltage signal that offers input terminal 41a to detect the size of the energising resistance of above-mentioned power-on circuit A.

Here, the situation to any one break down (the contact melting is bonding) of

safety switch

24,25 describes.As shown in Figure 4, the situation of fault has for example taken place at safety switch 24, when the door 22 of micro-wave oven was opened, the contact of safety switch 24 (c-b) still disconnected, so, be off state between resistance 44 that links to each other with the lead-out terminal 41 of microcomputer 41 and ground.Under this circuit state, the DC voltage dividing potential drop that will provide from the lead-out terminal 41b of microcomputer 41 with resistance 44 and infinitely-great resistance is provided, the microcomputer 41 that receives the voltage signal of this dividing potential drop can judge that the energising resistance of above-mentioned electrical path A is infinity, and promptly at least one side breaks down (or the wiring that constitutes above-mentioned electrical path is broken) in the

safety switch

24,25.

Also have, but the on/off state of microcomputer 41 detecting gate switches 29.For example, an end ground connection of door switch 29, the other end provides DC voltage by resistance, and the other end of door switch 29 is connected with the input of the tie point of resistance with microcomputer 41.Like this, microcomputer 41 can be left or be closed by the value detecting gate of the voltage signal that offers above-mentioned input.And when microcomputer 41 was connected at door switch 29, the door that is judged as micro-wave oven was closing; When door switch 29 disconnects, be judged as door and opening.

Then, with reference to the effect of flowchart text said structure shown in Figure 5, particularly judge the control when

safety switch

24,25 etc. breaks down.Judge the content of the control section when

safety switch

24,25 etc. breaks down in the flowcharting microcomputer 41 of this Fig. 5 in the control program of storage.

At first, among the step S1 in Fig. 5, whether microcomputer 41 is opened according to the on/off state decision gate 22 of detecting gate switch 29, here, when door 22 is opened, enter "Yes" in step S1, the fault of microcomputer 41

detection safety switches

24,25 etc. is carried out detection with the predetermined stipulated time (for example several seconds) and is moved.

Specifically, enter step S2, microcomputer 41 is from lead-out terminal 41b output dc constant voltage, simultaneously, the voltage signal that receives according to input terminal 41a detects the resistance of electrical path A (through the electrical path between the contact (c-b) of safety switch 24, between the contact (c-b) of a winding 34a of transformer 34, safety switch 25).Then, whether infinitely great microcomputer 41 judge the resistance R (step S3) of above-mentioned detection.

When the resistance value R that detects was infinity, at least one that is judged as in the

safety switch

24,25 broke down (or the wiring that constitutes electrical path is broken), enters "Yes" in step S3, carried out first abnormity notifying (step S4).At this moment, as first abnormity notifying, for example go up and show " EEEE " and make buzzer produce buzzing at the display of operation screen (specifically, time showing use seven segment type displays).This first abnormity notifying represents that at least one side's

safety switch

24,25 breaks down.Then, enter step S5, whole running actions are after this stopped, promptly forbidding heating running operation.

Also have, in step S3, when the resistance value R of detection is not infinity, enter "No", judge that whether above-mentioned resistance value R is than predetermined upper limit resistance R max big (step S6).Here, two

safety switches

24,25 just often, the resistance of above-mentioned electrical path A depends on the resistance value of a winding 34a of transformer 34 basically, though exist along with the difference of product has dispersion, all is the value in predefined certain limit.In contrast, when the abrasion of electric component increased the weight of (for example the loss of 34 winding 34a of transformer increases the weight of), the resistance value R of electrical path A became greater than the value of above-mentioned certain limit, promptly became than the also big value of predetermined upper limit resistance value Rmax.Also have, when the degradation of insulation of electronic unit increased the weight of (for example the degradation of insulation of transformer 34 winding 34a increases the weight of), the resistance value R of electrical path A became less than the value of above-mentioned certain limit, promptly became than the also little value of predetermined lower limit resistance value Rmin.

Therefore, under the situation of a winding 34a of transformer 34 loss, in the judgement of above-mentioned step S6, enter "Yes", carry out second abnormity notifying (step S7).At this moment, as second abnormity notifying, for example on the display of operation screen, show " E01 " and make buzzer produce buzzing.The winding 34a loss of this second abnormity notifying indication transformer 34.And, even do not have obstacle basically because the former state execution adds heat run yet, so, this second unusual situation is: return main program behind the control program (checking operation) of the fault of finish to carry out

judging safety switch

24,25 etc., become running holding state (waiting for the states of the various operated keys on the operating operation screen).

On the other hand, in above-mentioned step S6, when resistance value R is not more than upper limit resistance value Rmax, enter "No", judge that whether resistance value R is less than lower limit resistance value Rmin (step S8).At this moment, if the secondary winding 34a degradation of insulation of transformer 34 increases the weight of, then resistance value R becomes also littler than lower limit resistance value Rmin, so, in step S8, enter "Yes", carry out the 3rd abnormity notifying (step S9).At this moment, as the 3rd abnormity notifying, for example on the display of operation screen, show " E02 " and make buzzer produce buzzing.The degradation of insulation of a winding 34a of the 3rd abnormity notifying indication transformer 34.

Then, under the 3rd unusual situation, also identical with the above-mentioned second unusual situation, even almost do not have obstacle owing to heat in the same old way yet, so, return main program behind the control program of the fault of end execution

judgement safety switch

24,25 etc., become the operation holding state.

Also having, is under above-mentioned second unusual and the 3rd unusual situation in judgement, can carry out to add heat run, replaces but can forbid also that after this running is moved.

So, if employing said structure, then during some the breaking down in two

safety switches

24,25, detect action by when door 22 is opened, carrying out, detect the conducting state between each contact b of

safety switch

24,25, specifically detect the resistance of electrical path A, for example when the resistance of above-mentioned control is infinity, can judge that an above-mentioned side's

safety switch

24,25 breaks down (i.e. first abnormality).And, under the situation of this structure, even do not flow through overcurrent owing to

safety switch

24,25 breaks down yet, so, further improved security.Also have, can not need to have earlier the pilot switch 7 of structure (with reference to Fig. 8 and Fig. 9), can not need the bar 13 of pilot switch special use, so, can make designs simplification, make product cost low.

Also have, in said structure, the door checkout gear as the open and-shut mode of detecting gate 22 for example is provided with door switch 29, but owing to can make door switch 29 and safety switch 25 carry out switch motion synchronously, so, can not need the bar 13 of pilot switch special use really.Also have, formerly have in the micro-wave oven of structure, door switch 29 usually and pilot switch be provided with separately, so, can not make the manufacturing cost raising owing to door switch 29 is set.Here, formerly have in the structure, the reason that door switch 29 is set is to make microcomputer to know the switching of door.

Also have, in said structure, be judged as

safety switch

24,25 when breaking down, just forbid whole running operations after this, therefore, can prevent from when either party's safety switch breaks down, also to carry out in the same old way and add heat run.And, in this case, because the user can not make the micro-wave oven running, so, must repair micro-wave oven, improved security.

And then, in said structure, judge during at the resistance value R that detects and (for example to be in second abnormality greater than setting value (being upper limit resistance value Rmax), the state of the winding 34a loss of transformer 34), so, can notify second abnormality, the user can discern micro-wave oven reliably and be in second abnormality.And then also have, when the resistance value R that detects is lower limit resistance value Rmin less than setting value, conclude and (for example be in the 3rd abnormality, the state of a winding 34a degradation of insulation of transformer 34), so, can notify the 3rd abnormality, the user can discern micro-wave oven reliably and be in the 3rd abnormality.

Above-mentioned microwave oven structure is the structure that is used to illustrate the abnormality detection principle of safety switch, and actual microwave oven structure is the relay that increases various loads and make these load power on/off in said structure.Therefore, with reference to Fig. 6 and Fig. 7 concrete structure as the actual micro-wave oven micro-wave oven of heater (for example with) is described.Have, in circuit diagram shown in Figure 6, the structure identical with structure in the circuit diagram shown in Figure 1 is marked with identical symbol again.

In above-mentioned Fig. 6, be provided with main relay 46 near on the position of transformer 34 1 sides than the safety switch on the power line 32 25.And, than the safety switch on the power line 31 24 near the position of transformer 34 1 sides and than the main relay on the power line 32 46 near between the parts of transformer 34 1 sides, lamp 47 and be used to rotate and change the RT motor 48 that drives rotating disk in the stove in parallel.

Also have, between said power 31 and power line 32, be connected in parallel with motor 48 with lamp 47 in the above-mentioned stove: with culinary heater 49 of grill and series circuit that the grill relay 50 of these heater 49 power on/off is in series, the series circuit that parallel circuit after culinary heater 51 of open type and 52 parallel connections of Hot-air fan motor and the open relay 53 that above-mentioned heater 51 and motor 52 is carried out power on/off are in series, and the series circuit that is in series of the motor 54 that will make the heating room ventilation and the fan motor relay 55 that this motor 59 is carried out power on/off.

And, with position that the end of a winding 34a of transformer 34 on the power line 31 links to each other on, be provided with the stove relay 56 that magnetic controller is carried out power on/off.Also have, above-mentioned main relay 46, grill relay 50, open relay 53, fan motor relay 55 and stove relay 56 carry out break-make control by control circuit 35 (microcomputer 41) respectively.Also have, the RT motor relay that RT motor 48 is carried out power on/off is connected with above-mentioned RT motor 48, by utilizing control circuit 35 (microcomputer 41) that above-mentioned RT motor relay is carried out that break-make is controlled independently to RT motor 48 control of switching on.

In addition, 35 pairs of displays 57 that are provided with on the operation screen of above-mentioned control circuit drive control, import the switching signal of shielding the various operated keys 58 that are provided with from operation simultaneously.Aforementioned display device 57 is made of the display that shows current time and the display of cooking time and demonstration cooking menu etc.Also have,, be provided with cooking menu key, time set key, beginning key and cancel key etc. as various operated keys 58.

Then, with reference to the effect of flowchart text said structure shown in Figure 7, particularly judge the control (the detection action when door is opened) of the fault of

safety switch

24,25 etc.The flow chart of this Fig. 7 is shown in the content of the control section of the fault of judging

safety switch

24,25 etc. in the control program of storage in the microcomputer 41 of control circuit 35.

At first, in the step of Fig. 7 S101, whether microcomputer 41 is being opened by the on off operating mode decision gate 22 of detecting gate switch 29.Here, when door 22 is opened, in step S101, enter " deciding ", the detection action (step S102-S113) of the fault of the

detection safety switch

24,25 of explanation below microcomputer 41 was carried out with the predetermined stipulated time (for example 1～2 second) etc.

Specifically, enter step S102, microcomputer 41 is connected relay 46, then enters step S103, and microcomputer 41 detects the processing of the fault of

safety switch

24,25 at first.Specifically, detect energising resistance between

safety switch

24,25 each contact b, when the resistance value that detects be infinity, at least one that is judged as in the

safety switch

24,25 breaks down.And, the above-mentioned judged result of microcomputer 41 storages.

Then, enter step S104, check in the stove lamp 47 and RT motor 48 whether loss or degradation of insulation according to the resistance of above-mentioned detection.Detect processing in the same manner with the processing of above-mentioned step S6 and S8.Promptly, microcomputer 41 is in the resistance R that detects during greater than upper limit set value Rmax1, being judged as is second unusual (electronic unit, be

lamp

47 and 48 losses of RT motor in the stove), in resistance R during less than lower limit set value Rmin, being judged as is the 3rd unusual (above-mentioned electronic unit degradation of insulation), stores this judged result.

Afterwards, owing to disconnect main relay 46, so, enter step S105, microcomputer 41 is connected main relay 46 and grill relay 50, then enter step S106, microcomputer 41 is carried out to detect and is had or not the loss of the culinary heater 49 of grill or the processing of degradation of insulation, and this detection is handled and the processing of above-mentioned step S6 and S8 is similarly carried out.Promptly, connection resistance between each contact b of microcomputer 41 detection safety switches 24,25, at the resistance value R of this detection during greater than upper limit set value Rmax2, predicating is second unusual (electronic unit is heater 49 losses), at resistance value R during less than lower limit set value Rmin2, be judged as the 3rd unusual (above-mentioned heater 49 degradation of insulation), store this judged result.

Then, owing to disconnect main relay 46 and grill relay 50, so, enter the step 107, microcomputer 41 is connected main relay 46 and open relay 53, then, enter step S108, microcomputer 41 execution detection culinary heaters 51 of open type and motor 52 have the processing of lossless or degradation of insulation.This detection is handled and the processing of above-mentioned step S6 and S8 is similarly carried out.Promptly, energising resistance between each contact b of microcomputer 41 detection safety switches 24,25, at the resistance value R that detects during greater than upper limit set value Rmax3, being judged as is second unusual (electronic unit is heater 51 and motor 52 losses), at resistance value R during less than lower limit set value Rmin3, being judged as is the 3rd unusual (degradation of insulation of above-mentioned electronic unit), stores this judged result.

Then, owing to disconnect main relay 46 and open relay 53, so, enter step S109, microcomputer 41 is connected main relay 46 and stove relay 56, then enters step S110, and microcomputer 41 is carried out the processing that a winding 34a who detects the culinary transformer 34 of stove has lossless or degradation of insulation.This detection is handled and the processing of above-mentioned step S6 and S8 is similarly carried out.Promptly, energising resistance between each contact b of microcomputer 41 detection safety switches 24,25, at the resistance value R that detects during greater than upper limit set value Rmax, being judged as is second unusual (electronic unit is transformer 34 losses), at resistance value R during less than lower limit set value Rmin, being judged as is the 3rd unusual (degradation of insulation of above-mentioned electronic unit), stores this judged result.

Afterwards, because

main relay

46 and 56 disconnections of stove relay, so, entering step S111, microcomputer 41 is connected main relay 46 and fan motor relays 55, then, enters step S112, and microcomputer 41 execution detect the processing that fan electromotor 54 has lossless or degradation of insulation.This detection processing and above-mentioned step S6 and S8 handle and similarly carry out.Promptly, energising resistance between each contact b of microcomputer 41 detection safety switches 24,25, at the resistance value R that detects during greater than upper limit set value Rmax4, being judged as is second unusual (electronic unit is transformer 54 losses), at resistance value R during less than lower limit set value Rmin4, being judged as is the 3rd unusual (degradation of insulation of above-mentioned electronic unit), stores this judged result.

Then, because main relay 46 and fan motor relay 55 disconnect, so, entering step S113, microcomputer 41 is showing unusual more than a kind on the display 57 when having stored unusual more than a kind as the judged result of storage.And, when

safety switch

24,25 breaks down, whole running actions are after this stopped, promptly forbidding adding the heat run action.Here, when detecting unusual outside the fault of

safety switch

24,25, even add heat run and also do not have obstacle basically owing to carry out in the same old way, so, after finishing to carry out the control program of the fault of judging

safety switch

24,25, return main program, become the running holding state, and, also can be outside the fault that detects

safety switch

24,25 unusual the time, also stop whole runnings actions after this.

If adopt the present embodiment that constitutes like this, can access and identical effect and the effect of effect, effect that is used to illustrate that the structure that detects operating principle obtains.Particularly in the above-described embodiments, owing to connect a plurality of relays successively, so, can judge easily that a plurality of loads are the unusual and fault of a plurality of electronic units.In addition, in the above-described embodiments, owing to carried out the action of the fault of checking

safety switch

24,25 and a plurality of electronic units with 1～2 second left and right sides time, so, even 10,000 one or two

safety switches

24,25 break down simultaneously, even connect between each contact (c-a), owing to the about 3 second time of process till driving to the magnetic controller vibration, so, can before driving, the magnetic controller vibration detection of end move, can fully guarantee security.

In addition, in the above-described embodiments, when opening, carries out at door 22 fault detect of

safety switch

24,25 fault detects and a plurality of electronic units, but also can constitute like this: when door 22 is opened, only carry out the fault detect of

safety switch

24,25, when the operated key that under the state that door 22 is opened operation is shielded has carried out predetermined special operational, carry out the fault detect of a plurality of electronic units.If constitute like this, do not produce the driving sound of relay when opening basically owing to door 22, so, there is not hearing to disturb.One of diagnostic method when in addition, the detection method of utilizing the special operational of aforesaid operations key to begin to carry out the fault detect action of a plurality of electronic units can be repaired micro-wave oven as maintenance mans and utilizing.

In addition, in the above-described embodiments, after detecting

safety switch

24,25 faults, continue to carry out the fault detect of a plurality of electronic units, but be not limited to this, also can constitute like this: detect

safety switch

24,25 and whether break down, if do not carry out the fault detect of a plurality of electric components with regard to stopping to move.Also have, in the above-described embodiments, it is the structure that when door 22 is opened, detects the fault of

safety switch

24,25 etc., but be not limited to this, for example also can be under the state that door 22 is opened, be the fault detect action that condition is carried out

safety switch

24,25 etc. with the predetermined operated key in the operated key on the operating operation screen.In addition, in the above-described embodiments, in

power line

37,32, be provided with two

safety switches

24,25, but also can replace the safety switch that is provided with more than three.At this moment, specifically, can on a power line, two or more safety switches be set.

From above explanation as can be known, the present invention includes switch checkout gear and control device, above-mentioned switch checkout gear is when door is opened, detection is opened side joint point (with the common junction of at least two safety switches) with door and is linked to each other, detect these and open conducting state between side joint point, above-mentioned control device makes the switch checkout gear detect action when door is opened, therefore, can prevent to flow through when safety switch from breaking down overcurrent, can judge that fault has taken place in two safety switches any one simultaneously, have simple in structure and can reduce the excellent results of product cost.

Claims

1. heating device, wherein, between the two poles of the earth of the power line of the primary side of the transformer that supplies power to described heating device from source power supply, safety switch is set, these safety switches respond described heating device heating clamber door switching and move, it is characterized in that:

Described each safety switch is respectively a double-throw type switch,

Described heating device has:

Among the fixed contact of the described safety switch of another example, when described door is closed, be connected, detect the switch checkout gear that described ground connection circuit passband has or not energising with the side fixed contact that opens the door by closure,

Detect described door open and-shut mode the door checkout gear and

2. according to the described heating device of claim 1, it is characterized in that begin the stipulated time, described control device makes described switch checkout gear detect action when described door is opened.

3. according to claim 1 or 2 described heating devices, it is characterized in that, be judged as by described switch checkout gear when unusual that described control device notice should be unusual and forbade adding the heat run action.

4. according to claim 1 or 2 described heating devices, it is characterized in that described switch checkout gear detects described two safety switches and opens resistance between the side fixed contact at door, simultaneously, when the resistance value that detects is infinity, judge that at least one side in the described safety switch breaks down.

5. according to the described heating device of claim 4, it is characterized in that described switch checkout gear greater than by the upper limit resistance value of the predefined scope of resistance value of the primary coil of transformer the time, is judged as second abnormality in the resistance value that detects.

6. according to the described heating device of claim 4, it is characterized in that described switch checkout gear less than by the lower limit resistance value of the predefined scope of resistance value of the primary coil of transformer the time, is judged as the 3rd abnormality in the resistance value that detects.

7. according to claim 1 or 2 described heating devices, it is characterized in that, a plurality of loads are set between described power line and make a plurality of relays of each load on/off; Described switch checkout gear is connected the fault of judging each load successively by making described a plurality of relay.

8. according to the described heating device of claim 7, it is characterized in that make the operated key of operation screen carry out special operational, promptly described control device makes described switch checkout gear detect action under the state that described door is opened.