JPH0975207A - Electric cooker heating control device - Google Patents

Abstract

(57) [PROBLEMS] To provide a heating control device for an electric cooker which prevents deterioration of switches and the like due to abnormal inrush current and has high safety. SOLUTION: A heating device of an electric cooker includes a halogen lamp 2 as a heat source, a limiting circuit 11 for limiting an inrush current to the halogen lamp 2, and a current detecting means 3 for detecting an input current to the halogen lamp 2. A control means 1 for performing heating control based on the output of the current detection means 3 and a key input means 4 for operating the cooker are provided. Then, when the value of the inrush current generated when the halogen lamp 2 is energized exceeds a predetermined value, the energization is stopped and a warning indicating that there is an abnormality is issued.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating control device for an electric rice cooker or the like which uses a halogen lamp for generating electromagnetic waves as a heat source.

[0002]

2. Description of the Related Art A radiant heating type electric rice cooker using a halogen lamp as a heat source is described in JP-A-7-39453. The basic circuit configuration is shown in FIG.
As shown in FIG. 5, a series circuit of a halogen lamp 61, a load 62, and a relay switch 63 is connected to both ends of the commercial AC power supply 60. Here, the load 62 plays a role of limiting the inrush current generated when the halogen lamp 61 is turned on by turning on the relay switch 63.

It should be noted that the current flowing through the halogen lamp 61 is detected and controlled in order to appropriately heat the halogen lamp 61, and a specific current detection circuit thereof is shown in FIG. In the figure, while the relay switch 63 is in the ON state, the current (AC current) flowing through the heater 61 ′ (and the load 62) of the halogen lamp 61 can be obtained by the current transformer 70 by reducing it to 1 / n on the secondary side thereof. , This current is converted into AC voltage by the resistor 72, and the diode 73, the capacitor 74, and the resistor 75
Converted to DC voltage by the microcomputer 76
Give to. The microcomputer 76 turns ON / OFF (duty) the switch 63 based on the detected current.
To control the current flowing through the halogen lamp 61.

[0004]

As described above, in an electric cooker using a halogen lamp, a large rush current flows at the moment when the halogen lamp is energized, and therefore a circuit (load 62) for limiting the rush current is provided. However, if an extremely large inrush current occurs due to some abnormality (for example, short circuit of load 62), it will be turned on by a switch such as a relay.
There is a problem that the contact of the switch is seriously damaged if the switch is turned on / off, and the life of the contact is shortened. Further, the conventional current detection circuit has a drawback that it is difficult to detect a wide range of current values because the current value is monitored and controlled for one judgment value.

It is an object of the present invention to provide a heating control device for an electric cooker which prevents deterioration of switches and the like due to an abnormal rush current and is highly safe.

[0006]

In order to achieve the above object, the present invention detects a halogen lamp as a heat source, a load for limiting an inrush current to the halogen lamp, and an input current to the halogen lamp. In a heating device of an electric cooker including a current detecting means, a control means for performing heating control based on the output of the current detecting means, and a key input means for operating the cooker, generated when the halogen lamp is energized. When the value of the inrush current exceeds a predetermined value, the energization is stopped and a warning indicating that there is an abnormality is issued.

In such a configuration, for example, when the load is short-circuited and an abnormally large inrush current flows, the output of the detection means exceeds a predetermined value (abnormality determination level), so that the control means is in an abnormal state. Then, the user is notified of this, and the cooking operation is stopped.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of this embodiment. In the figure, reference numeral 1 is a control means comprising a microcomputer, and a halogen lamp 2
The detected value of the current flowing through the sensor is received from the current detecting means 3.

Also, a key input is received from the key input means 4. The key input means has a plurality of keys such as a rice cooking key, a heat retention key, and a cancel key. On the other hand, the control means 1 controls the energization of the halogen lamp 2 via the heating means 7. Here, the heating means 7 is composed of a switch (relay switch) inserted in the current supply path.

When the detected current value from the current detection means 3 exceeds a predetermined value, the control means 1 judges that it is in an abnormal state, stops the heating means 7, and simultaneously displays the display means 5 and sounds. The means 6 is driven to give a warning that there is an abnormality. The display means 5 can also display the detected current value at the time of the abnormality. This display may be performed automatically, or a display-dedicated switch 9 may be provided and displayed in response to the operation of the switch 9. Instead of providing the display-only switch 9, the display may be made by using an existing key operation combination.

FIG. 2 shows a current supply path of the halogen lamp 2,
The details of the current detection means 3 are shown. Commercial AC power supply 10
A halogen lamp 2, a limiting circuit 11 for limiting the inrush current, a relay switch 12, and a current transformer 13 are connected in series at both ends of the plug via a plug (not shown).

The limiting circuit 11 is composed of a load such as a resistor. On the secondary side of the current transformer 13, 1 / n (1 / n is the transformer 1
An alternating current reduced in current ratio of 3) flows. This alternating current is converted into an alternating voltage by the resistor 15. The AC voltage is further converted into a DC voltage by the diode 16, the capacitor 17 and the resistor 18, and then applied to the control means 1.

Next, the operation of FIG. 2 will be described. When the key switch means 4 is operated, the control means 1 starts the heating control operation and turns on / off the relay switch 12. As a result, a current flows through the halogen lamp 2. Since the resistance of the heater of the halogen lamp 2 is low at first, an inrush current flows when the relay switch 12 is turned on, but this inrush current is limited by the limiting circuit 11.

Incidentally, when the relay switch 12 is turned on, an AC voltage as shown in FIG. 4A is obtained at the output side of the current transformer 13, and the AC voltage is converted into a DC voltage as shown in FIG. 4B. , Does not exceed the specified value (abnormal level).

When an abnormality occurs in the power supply system due to some cause (for example, the limiting circuit 11 is short-circuited),
The inrush current becomes very large. At this time, the current value detected by the current detection means 3 exceeds a predetermined value (abnormal level) preset in the control means 1 as shown in FIG. 4C, so the control means 1 judges that it is in an abnormal state, The relay switch 12 is fixed in the OFF state. Therefore, repeated ON / OFF of the relay switch 12 under a large current is avoided, so that the switch and the like are not damaged and the safety of the electric cooker is secured.

When the control means 1 makes an abnormality determination as described above, the display means 5 should further inform the user of the abnormality.
For example, the display as shown in FIG. Although the detected abnormal current value can be displayed on the display means 5 as shown in FIG. 5B, this display may be performed automatically or by pressing a key switch. You may do it. The current display example in FIG. 5B is a value when A / D conversion is performed in the detection current control means 1.

Further, since the control means 1 prohibits the subsequent key input means 4 from accepting a key input when such an abnormality occurs, when the abnormality occurs, the control means 1 holds the stopped state thereafter. The cancellation of this stopped state is left to the user or service person. When the reset key 8 is operated, the stopped state is released.

Next, FIG. 3 shows another configuration of the current detecting means 3. Here, a resistor 31 and a switching transistor 32, and a resistor 33 and a switching transistor 34 are connected in parallel to the resistor 15 as shown in the drawing, and the switching transistors 32 and 34 are ON / OFF controlled by the control means 1. It is like this.

This is such that the resistance value that determines the magnitude of the AC voltage generated on the secondary side of the current transformer 13 can be varied, and the detection sensitivity is switched by this. Then, this sensitivity switching is performed according to the cooking mode. A mode can be selectively selected by various keys provided on the key input means 4.

For example, a rice cooking mode, a heat retention mode, a standby mode, etc. can be selected. And, for example, in rice cooking mode,
The resistance value on the secondary side of the transformer 13 is reduced. On the other hand, in the heat retention mode, a slight amount of current flows through the halogen lamp, so the resistance value is increased to increase the detection sensitivity. In standby mode, the resistance is further increased to increase the sensitivity.

The resistance of the transistors 32 and 34 is set to O.
The smaller the value is, the smaller the value becomes, and the larger the value when it is turned off. The control means 1 controls the O of the transistors 32 and 34 depending on the mode.
The sensitivity is changed by controlling N and OFF, and the predetermined value (abnormality determination level) is also changed. Thus, FIG.
According to the configuration, the abnormal current can be monitored according to each mode, and the safety is greatly improved.

[0022]

According to the present invention, it is possible to prevent self-damage of an electric cooker due to an abnormal inrush current when driving a halogen lamp, and to improve safety and reliability. is there. Further, according to claim 5, since the current detection sensitivity and the predetermined value (abnormality determination level) are changed for each mode in which the amount of current supplied to the halogen lamp is different, the abnormal state can be reliably detected in each mode, and the reliability can be improved. The property is further improved.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a circuit diagram of a main part thereof.

FIG. 3 is a circuit diagram showing a modified example of the circuit.

FIG. 4 is an operation explanatory diagram of the embodiment of the present invention.

FIG. 5 is a diagram showing a display example according to the embodiment of the present invention.

FIG. 6 is a circuit diagram of a conventional example.

FIG. 7 is a diagram showing a conventional current detection circuit.

[Explanation of symbols] 1 control means 2 halogen lamp 3 current detection means 4 key input means 5 display means 6 sounding means 7 heating means 8 reset switch 11 limiting circuit (load) 12 relay switch 15, 31, 33 resistance

Claims (5)

[Claims] 1. A halogen lamp as a heat source, a load for limiting an inrush current to the halogen lamp, a current detecting means for detecting an input current to the halogen lamp, and heating based on an output of the current detecting means. In a heating device for an electric cooker including a control means for controlling and a key input means for operating the cooker, when the value of the inrush current generated when the halogen lamp is energized exceeds a predetermined value, the energization is stopped. In addition, a heating control device for an electric cooker, which warns that there is an abnormality. 2. The heating control device according to claim 1, wherein when the value of the inrush current exceeds the predetermined value, the input by the key input means is not accepted and re-cooking is prohibited. 3. The heating control device according to claim 1, wherein the warning is given by a display means and a sounding means. 4. The heating control device according to claim 1, wherein the value of the current exceeding the predetermined value is displayed on the display means. 5. The heating control device for an electric cooker according to claim 1, wherein the current detection sensitivity of the current detection means is changed according to the cooking mode and the predetermined value is switched.