JP2006012671A - Induction heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To rapidly detect abnormality with an inexpensive microcomputer without complicating a circuit structure. <P>SOLUTION: This induction heating cooker (rice cooker) is provided with: an induction heating coil 4; an inverter circuit 13; a driving circuit 14; the microcomputer 15; a power voltage detection means 20; a power current detection means 21; and a coil current detection means 22. Signal output lines 23a, 23b and 23c from the power current detection means 21, the power voltage detection means 20 and the coil current detection circuit 22 are put together and connected to one interrupt terminal 15a of the microcomputer 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an induction heating cooker such as a rice cooker or an electromagnetic cooker.

  This type of induction heating cooker includes an induction heating coil, an inverter circuit that converts an input DC voltage into a high frequency voltage and applies the induction voltage to the induction heating coil, a drive circuit that drives the inverter circuit, and the drive circuit And a microcomputer for transmitting a drive signal to the pot, and the induction heating coil induction-heats a pot which is an object to be heated through a partition plate made of a non-conductive material.

  Prior art document information related to the induction heating cooker of the present invention includes the following.

Japanese Patent No. 3109173

  In this Patent Document 1, a power supply current detection means for detecting a power supply current abnormality of the inverter circuit, a power supply voltage detection means for detecting a power supply voltage abnormality of the inverter circuit, and a coil current abnormality that is passed through the induction heating coil are detected. There is provided an inverter control circuit provided with detection means for detecting an abnormality occurring in an electric circuit, such as a coil current detection means for detecting.

  Here, the microcomputer as the control means has a plurality of input terminals and output terminals. Among them, the input terminal includes an interrupt terminal that can be recognized at high speed, a normal terminal that has a lower recognition speed than the interrupt terminal, and the like. When the detection means is connected to the normal terminal of the microcomputer, the occurrence of abnormality cannot be recognized instantaneously, and it may not be recognized when the abnormality is instantaneous. On the other hand, when the detection means is connected to the interrupt terminal of the microcomputer, the occurrence of an abnormality can be recognized instantly and reliably, but if the number of interrupt terminals increases, the microcomputer becomes expensive and expensive.

  For this reason, in Patent Document 1, the detection means is connected to the normal terminal of the microcomputer, and an abnormality maintaining circuit is provided between them for maintaining an abnormal condition until the microcomputer can recognize it.

  However, in the configuration of Patent Document 1, the microcomputer cannot quickly detect an abnormality particularly in an inverter circuit to which a high voltage is applied. In addition, in order for the microcomputer to detect an abnormality, it is necessary to further add a complicated circuit to maintain the abnormal state, so there is a problem that the cost increases.

  Accordingly, an object of the present invention is to provide an induction heating cooker that can quickly detect a plurality of abnormalities with an inexpensive microcomputer without complicating the circuit configuration.

  In order to solve the above problems, an induction heating cooker according to the present invention includes an induction heating coil that induction-heats an object to be heated, and an inverter circuit that converts an input DC voltage into a high-frequency voltage and applies the high-frequency voltage to the induction heating coil. A drive circuit for driving the inverter circuit; a microcomputer for transmitting a drive signal to the drive circuit; power supply voltage detection means for detecting a power supply voltage abnormality of the inverter circuit; and a power supply for detecting a power supply current abnormality of the inverter circuit In an induction heating cooker comprising current detection means and coil current detection means for detecting an abnormality in the coil current applied to the induction heating coil, the power supply current detection means, the power supply voltage detection means, and the coil current detection means The signal output lines are aggregated and connected to one interrupt terminal of the microcomputer.

  In this induction heating cooker, each of the detecting means preferably has a comparator for detecting the presence / absence of abnormality by level comparison, and the output at the time of abnormality by these comparators is preferably set to a low level.

Further, the aggregated signal output lines are branched and further connected to the level detection terminal of the microcomputer. When the microcomputer indicates a signal indicating an abnormality to the interrupt terminal, the inverter circuit is connected via the drive circuit. It is preferable that the abnormal point is identified by reading the level detection terminal.
In this case, it is preferable to further provide display means for displaying the abnormal part.

  In the induction heating cooker of the present invention, the signal output lines of the three detection means that need to be quickly stopped are aggregated and connected to one interrupt terminal of the microcomputer, so that the microcomputer is mounted on the microcomputer. The number of interrupt terminals can be reduced. Therefore, it is possible to quickly detect a plurality of abnormalities with an inexpensive microcomputer with few interrupt terminals and to prevent the circuit configuration from becoming complicated.

  Moreover, since the output at the time of abnormality by the comparator which each detection means has is made into the low level, the signal output lines of each detection means can be collected reliably, and it can be detected by one interrupt terminal.

  In addition, the signal output lines that have been consolidated into one branch are branched, and the branch lines are connected to the level detection terminal of the microcomputer so that the microcomputer can identify the location where the abnormality has occurred. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a rice cooker 1 that is an induction heating cooker according to a first embodiment of the present invention. The rice cooker 1 generally includes an inner pot 2 that is a pot for storing food, a rice cooker body 3 that includes a protective frame 3a made of a non-conductive material for storing the inner pot 2, an induction heating coil 4, and an inner pot. 2, a temperature sensor 5 for 2, a lid 6, a lid heater 7, a temperature sensor 8 for the lid, and a circuit board 10.

  As shown in FIG. 2, the circuit board 10 includes a rectifier circuit 12 connected to an AC power source 11. The rectifier circuit 12 converts the input DC voltage into a high-frequency voltage and converts it into the induction heating coil 4. An inverter circuit 13 to be applied, a drive circuit 14 for driving the inverter circuit 13, and a microcomputer 15 as control means are mounted.

  The rectifier circuit 12 and the inverter circuit 13 are connected by a pair of power supply lines 16a and 16b. The induction heating coil 4 and the inverter circuit 13 are connected by a pair of connection lines 17a and 17b. The inverter circuit 13 and the drive circuit 14 are connected by a connection line 18. The drive circuit 14 and the microcomputer 15 are connected by a connection line 19. The connection line 19 is connected to a normal terminal of the microcomputer 15.

  And in this embodiment, in order to detect the power supply voltage abnormality and power supply current abnormality of the said inverter circuit 13 which are abnormality which needs to stop operation | movement rapidly, and the coil current abnormality supplied to the said induction heating coil 4 are detected. In addition, three detection means 20, 21, 22 are mounted. Specifically, in order to detect an abnormality in the power supply voltage of the inverter circuit 13, a power supply voltage detection means 20 that outputs a signal based on the detected voltage value is disposed between the power supply lines 16a and 16b. . Further, in order to detect an abnormality in the power supply current of the inverter circuit 13, power supply current detection means 21 for outputting a signal based on the detected current value is interposed in the power supply line 16b. Further, in order to detect an abnormality in the coil current supplied to the induction heating coil 4, a coil current detection means 22 for outputting a signal based on the detected current value is disposed on the connection line 17b.

Signal detection lines 23a, 23b, and 23c are connected to the detection means 20, 21, and 22, respectively. These signal output lines 23a, 23b, and 23c are connected to negative terminals of comparators 24a, 24b, and 24c that detect the presence or absence of abnormality by level comparison. The positive terminals of the comparators 24a, 24b, and 24c are connected to the power supply terminal _Vcc via the resistance element 25 and grounded via the resistance element 26. The output terminals of the comparators 24a, 24b, and 24c are connected to signal output lines 27a, 27b, and 27c, and the signal output lines 27a, 27b, and 27c are connected to positive terminals of the diodes 28a, 28b, and 28c. ing. Furthermore, the signal output lines 29a, 29b, and 29c are connected to the negative terminals of the diodes 28a, 28b, and 28c, and these are aggregated into one signal output line 30. The signal output line 30 is connected to the power supply terminal _Vcc via the resistance element 31, and is also connected to the interrupt terminal 15a of the microcomputer 15.

  In this rice cooker 1, when an abnormality occurs in any of the detection means 20, 21, and 22, the integrated signal output line 30 outputs a low (L) level regardless of which abnormality occurs. The When this L level signal is input to one interrupt terminal 15a that can be recognized (processed) at high speed in the microcomputer 15, the microcomputer 15 quickly determines that an abnormality has occurred in any part, Processing can be performed to stop the inverter circuit 13 via the drive circuit 14.

  Thus, in the rice cooker 1 of this embodiment, the signal output lines 23a, 23b, and 23c of the three detection means 20, 21, and 22 that need to be quickly stopped are replaced with one signal output line 30. By collecting and connecting to one interrupt terminal 15a of the microcomputer 15, it is possible to detect abnormalities at three locations, so that the number of interrupt terminals 15a mounted on the microcomputer 15 can be reduced. Therefore, a plurality of abnormalities can be quickly detected by an inexpensive microcomputer 15 having a small number of interrupt terminals 15a, and the circuit configuration can be prevented from becoming complicated.

  Next, specific control of the heat treatment by the microcomputer 15 will be described.

  In this heat treatment, as shown in FIG. 3, the microcomputer 15 first outputs a drive signal for driving the inverter circuit 13 to the drive circuit 14 in step S1-1. Thereafter, in step S1-2, it is detected whether or not an abnormality (L) signal is input to the interrupt terminal 15a. If an abnormal signal is input, the process proceeds to step S1-3. If an abnormal signal is not input, the process returns to step S1-1.

  In step S1-3, the operation status of the control performed until the occurrence of the abnormality is stored, and then in step S1-4, output of the signal to the drive circuit 14 is stopped in order to temporarily stop the inverter circuit 13. Execute pause processing. Next, in step S1-5, 1 is added to the number (N) of occurrence of abnormality, and then in step S1-6, it is detected whether or not the number of abnormality (N) has become 3 (times). If N is 3, the process proceeds to step S1-7. If N is not 3, the process proceeds to step S1-9.

  In step S1-7, after performing the stop process for completely stopping the rice cooking process or the heat retaining process including the heat process, in step S1-8, the number of abnormalities (N) is reset (0) and the process ends.

  In step S1-9, after resetting and starting the 3-second counter for restarting, in step S1-10, the process waits until the 3-second counter is counted up. That is, when an abnormality is detected in step S1-2, the inverter circuit 13 is completely stopped when the number of abnormalities exceeds a preset number, and when it is within the number, the inverter circuit 13 is stopped for a predetermined time. When the 3-second counter counts up, the stored operation status is read in step S1-11, and then the process returns to step S1-1 to output a drive signal to continue the rice cooking process or the heat retaining process. The abnormal number (N) is also reset when the rice cooking process or the heat retaining process is completed.

  4 and 5 show the rice cooker 1 of the second embodiment. In this rice cooker 1, as shown in FIG. 4, the signal output lines 29 a, 29 b, and 29 c are provided with resistance elements 32 a, 32 b, and 32 c having different resistance values, and branched from the signal output line 30. The line 30a is connected to the level detection terminal 15b of the microcomputer 15. When an abnormality (L) signal is input to the interrupt terminal 15a, the voltage of the signal output line 30 is detected from the level detection terminal 15b, and any of the detection means 20, 21, and 22 detects abnormality according to the detection level. It is different from 1st Embodiment by the point which judged whether it was done and the abnormal part was displayed on the display panel 9 mounted in the rice cooker 1. FIG.

  Next, specific control of the heat treatment of the second embodiment by the microcomputer 15 will be described.

  In the heat treatment of the second embodiment, as shown in FIG. 5, the microcomputer 15 first outputs a drive signal for driving the inverter circuit 13 to the drive circuit 14 in step S2-1. Thereafter, in step S2-2, it is detected whether or not an abnormality (L) signal is input to the interrupt terminal 15a. If an abnormal signal is input, the process proceeds to step S2-3. If an abnormal signal is not input, the process returns to step S2-1.

  In step S2-3, the operation state of the control performed until the abnormality occurs is stored, and then in step S1-4, output of the signal to the drive circuit 14 is stopped to temporarily stop the inverter circuit 13. Execute pause processing. In step S2-5, the voltage of the signal output line 30 is detected (read) from the level detection terminal 15b. In step S2-7, any of the detection means 20, 21, and 22 is abnormal based on the detected voltage value. Whether the signal has been output is specified and stored in the built-in storage means.

  Next, in step S2-7, 1 is added to the number of occurrences of abnormality (N), and in step S2-8, it is detected whether or not the number of abnormalities (N) has become 3 (times). If N is 3, the process proceeds to step S2-9. If N is not 3, the process proceeds to step S2-13.

  In step S2-9, after executing the stop process for completely stopping the rice cooking process or the heat retaining process including the heat process, the stored abnormal part is read in step S2-10. Next, in step S2-11, after the location where the abnormality has occurred is displayed on the display panel 9, in step S2-12, the number of abnormalities (N) is reset (0) and the process ends.

  In step S2-13, after resetting and starting the 3-second counter for restarting, in step S2-14, the process waits until the 3-second counter is counted up. When the 3-second counter counts up, in step S2-15, the stored operation state is read, and then the process returns to step S2-1 to output a drive signal to continue the rice cooking process or the heat retaining process. The abnormal number (N) is also reset when the rice cooking process or the heat retaining process is completed.

  In the second embodiment, the signal output line 30 aggregated into one is branched, and the branch line 30a is connected to the level detection terminal 15b of the microcomputer 15 to thereby select one of the three detection means 20, 21, and 22. The microcomputer 15 can identify the location where an abnormality has occurred. And since the abnormal part is memorize | stored in the memory | storage means incorporated, and it is displaying on the display panel 9 which is a display means, workability | operativity at the time of repair can be improved.

  In addition, the induction heating cooking appliance of this invention is not limited to the structure of the said embodiment, A various change is possible.

  For example, in the said embodiment, although the structure of this invention was applied to the rice cooker 1 of an induction heating system, even if it applies to an electromagnetic cooker, the same effect | action and effect can be acquired.

It is the schematic which shows the rice cooker which is the induction heating cooking appliance of this invention. It is a block diagram which shows the structure of the rice cooker of 1st Embodiment. It is a flowchart which shows the heating control of 1st Embodiment by a microcomputer. It is a block diagram which shows the structure of the rice cooker of 2nd Embodiment. It is a flowchart which shows the heating control of 2nd Embodiment by a microcomputer.

Explanation of symbols

1 ... Rice cooker (induction heating cooker)
2… Inner pot (object to be heated)
DESCRIPTION OF SYMBOLS 4 ... Induction heating coil 10 ... Circuit board 12 ... Rectifier circuit 13 ... Inverter circuit 14 ... Drive circuit 15 ... Microcomputer 15a ... Interrupt terminal 15b ... Level detection terminal 20 ... Power supply voltage detection means 21 ... Power supply current detection means 22 ... Coil current Detection means 23a to 23c ... signal output line 24a to 24c ... comparator 30 ... signal output line 30a ... branch line

Claims (4)

An induction heating coil that induction-heats an object to be heated, an inverter circuit that converts an input DC voltage into a high-frequency voltage and applies it to the induction heating coil, a drive circuit that drives the inverter circuit, and a drive to the drive circuit A microcomputer for transmitting a signal, a power supply voltage detecting means for detecting a power supply voltage abnormality of the inverter circuit, a power supply current detecting means for detecting a power supply current abnormality of the inverter circuit, and a coil current abnormality energized in the induction heating coil In an induction heating cooker provided with a coil current detection means for detecting
An induction heating cooker characterized in that signal output lines from the power supply current detection means, power supply voltage detection means and coil current detection means are aggregated and connected to one interrupt terminal of the microcomputer.   2. The induction heating cooker according to claim 1, wherein each of the detection units has a comparator that detects presence or absence of abnormality by level comparison, and an output at the time of abnormality by the comparator is set to a low level. Branching the aggregated signal output lines and further connecting to the level detection terminal of the microcomputer,
The microcomputer, when a signal indicating an abnormality is input to the interrupt terminal, stops the inverter circuit via the drive circuit, and reads the level detection terminal to identify an abnormality location. The induction heating cooker according to claim 1 or 2.   The induction heating cooker according to claim 3, further comprising display means for displaying the abnormal part.

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