JPH06229556A - Heater device - Google Patents

Abstract

PURPOSE:To provide a heater device capable of reducing the number of electronic component parts in a sensor circuit and improving an accuracy in measurement. CONSTITUTION:Signals got from an IR ray sensor 1 and a case temperature sensing sensor 3 of the IR ray sensor are inputted separately into a micro computer and a temperature of a heated item is calculated by a program stored in the micro computer, so that the number of component parts in a sensor circuit 9 can be reduced. In addition, since the micro computer is constructed to correct a dispersion of characteristic of a sensor device 14 with a signal got from a correction circuit 5, a temperature of the heated item can be calculated accurately. In addition, a voltage got from a constant voltage generating circuit 4 installed in the sensor circuit 9 is set to be a reference voltage of an IR ray sensor 1 and a sensor signal processing, so that a temperature of the heated item can be accurately measured without being influenced by a dispersion of electronic parts or noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device such as a microwave oven, and more particularly to a heating device for measuring the temperature of an object to be heated for the purpose of automatic cooking.

[0002]

2. Description of the Related Art Conventionally, in a heating device of this type, as shown in FIG. 6, infrared rays emitted from an object to be heated are intermittently incident on an infrared sensor 36 by a chopper 37, and a signal of the sensor is filtered by a filter circuit 38 and AC cut. After passing through the amplifier circuit 39, the chopper signal is synchronized with the synchronizing circuit 40. Incidentally, 49 is a chopper drive circuit. Further, the signal synchronized by 40 passes through the filter circuit 41 and the amplifier circuit 42, and is added by the adder circuit 43 with the signal amplified by the chopper temperature detecting element 44, and then the absolute value circuit 46 and the line approximation. It is configured to be input to a microcomputer (hereinafter referred to as a microcomputer) 48 via a circuit 47 and the like. Based on this input information, the microcomputer 48 controls the magnetron according to the menu to be cooked, and finishes heating. Automatic cooking was realized by changing the heating pattern.

[0003]

However, in the above-mentioned conventional configuration, the sensor unit does not rely on the software processing of the microcomputer so much and the circuit configuration is performed. Therefore, the circuit configuration becomes large and the product itself becomes large. ,
The cost of the product will be high, and the measured data will vary due to variations in circuit components.

The present invention is intended to solve the above-mentioned problems.
The purpose of is to have a compact circuit configuration. The second purpose is to improve the measurement accuracy.

[0005]

In order to achieve the first object, in order to achieve the first object, the heating device of the present invention includes an infrared sensor for detecting infrared light emitted from an object to be heated, and an infrared sensor. Case temperature detecting means for detecting the case temperature of the sensor, input means for individually taking in the signal of the infrared sensor and the signal of the case temperature detecting means, and signal of the infrared sensor taken in by the input means and case temperature detecting means And a control means for controlling the heating means on the basis of the estimated temperature.

In order to achieve the second object, heating means for heating an object to be heated, an infrared sensor for detecting infrared rays emitted from the object to be heated, and a case temperature for detecting a case temperature of the infrared sensor The detecting means, the input means for individually taking in the signal of the infrared sensor, the signal of the case temperature detecting means, and the signal of the estimating means, and the signal of the infrared sensor and the signal of the case temperature detecting means taken in by the input means are used. Temperature calculation means for calculating the estimated temperature of the object to be heated, correction means for giving correction information to the temperature estimation means, and control means for controlling the heating means based on the estimated temperature corrected based on the information of the correction means. It is composed of and.

Further, in order to achieve the second object, a heating means for heating an object to be heated, a constant voltage power source, and a constant voltage power source are provided on the same substrate and connected to the constant voltage power source as a reference. An infrared sensor for detecting infrared rays emitted from a heated object, a case temperature detecting means for detecting the case temperature of the infrared sensor, an infrared sensor signal, a signal of the case temperature detecting means, and a voltage value of a constant voltage power supply are individually provided. To be heated by using the input means taken in to the input means, the signal of the case temperature detection means taken in the input means and the signal of the infrared sensor taken in the input means based on the voltage value of the constant voltage power supply taken in the input means It is provided with a structure including a temperature calculation means for calculating the estimated temperature of the object and a control means for controlling the heating means based on the estimated temperature.

[0008]

According to the present invention, with the above configuration, the portion realized by the circuit is realized by the software processing of the microcomputer.
The number of electronic parts can be reduced, the product itself can be made smaller, and the cost of the product can be reduced.

Further, since the variation in the characteristics of each sensor unit from the reference sensor unit is stored in the sensor circuit as the correction information and the temperature of the object to be heated is calculated using the correction information, the sensor unit is used. The temperature of the object to be heated can be accurately estimated even if the characteristics of No. 1 vary.

Further, a constant voltage power source is provided in the sensor circuit,
By connecting the sensor and processing the sensor signal on the basis of the value, the variation of the sensor circuit can be absorbed, the influence of noise is reduced, and the measurement accuracy is improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 3, reference numeral 15 is a main body of the microwave oven,
Reference numeral 21 is an oven formed in the main body 15, 11 is a magnetron as a heating source for supplying microwaves to the inside 20 of the oven via the waveguide 12, and 13 is a heated object housed in the inside 20 of the oven. An object 14 is a sensor unit that receives infrared rays emitted from the object to be heated 13 and detects the temperature thereof. Further, 16 is a motor for rotating a placing plate 17 for placing the object 13 to be heated, and 18 is an oven chamber 20.
An internal light for illuminating the room, and a heater 19 as a heating source.

FIG. 2 is a side sectional view of the sensor unit 14. A pyroelectric element or a thermopile is used as the infrared sensor. In this embodiment, a case where a thermopile is used will be described. The sensor unit 14 includes a lens 10 arranged on the front surface of the thermopile 1, a lens holder 7 for holding the lens 10, a sensor circuit 9 including the thermopile 1 and electronic parts, a shield case 8 for protecting the sensor circuit 9 from noise, and the like. Become. The temperature sensor IC3, which is a component of the sensor circuit 9, is thermally coupled to the can case of the thermopile 1.

The sensor unit 14 is a microcomputer shown in FIG.
35 and the shield wire. Fig. 4 Control times
A block diagram of the road is shown. The commercial power source 22 is the low voltage transformer 2
It goes down in 3 and goes through the half-wave rectifier circuit 24, and then the constant voltage
Power supply V of microcomputer 35 through raw circuit 25_CCConnected to
It The ground is V_SS, 26 are reset ICs
It The reference voltage of the A / D of the microcomputer 35 is AV on the positive side._CCso
V_CCOn the negative side is AV_SSAnd V _SSConnected to. Also, my
The controller 35 is, in addition to the sensor circuit 9, fluorescent light as display means.
Display tube 27 and switch group 28 for instructing a cooking menu
-3 or a start switch 28 for instructing the start of cooking
-1 or a cancel switch 28 for instructing to cancel or cancel cooking
Set the switch group 28 consisting of 2 and cooking time etc.
An encoder 29 is connected. Further as a heating source
Heater 19 and the inside of the oven for illuminating the inside 20
A motor 1 for rotating the lamp 18 and the plate 17
Drive circuits 30, 31 and 3 for driving 6
2 are connected. Also controls the oscillation of the magnetron 11.
The inverter 33 and the relay circuit 34 are connected.

FIG. 1 shows a sensor circuit. The sensor circuit 9 includes a constant voltage generating circuit 4 for supplying a reference power source to the thermopile 1, an amplifier circuit 2 for amplifying the signal of the thermopile 1, a temperature sensor IC 3 for measuring the case temperature of the thermopile 1, and a semi-fixed resistor 5. The correction circuit 5 provides the microcomputer 35 with correction information such as -2. The constant voltage generating circuit 4 outputs a voltage of about 2.5 V. This is because the voltage (about 24 V) supplied from the control circuit is the constant voltage IC4.
It goes to about 5V by passing -1, and becomes about 2.5V by passing through the constant voltage circuit 4-2 composed of an operational amplifier. This constant voltage serves as a reference voltage for the thermopile 1 and the amplified signal of the thermopile 1. Further, this constant voltage is passed through the b terminal of the connector 6 to the A of the microcomputer 35.
/ D port (this voltage is hereinafter referred to as Vb). Further, the signal of the thermopile is about 5 in the amplifier circuit 2.
It is non-inverted and amplified by a factor of 00, and is connected to the microcomputer through the a terminal of the connector 6 (hereinafter, this voltage is referred to as Va), but the gain adjustment is performed using the semi-fixed resistor 2-2. Further, the correction circuit is composed of a semi-fixed resistor 5-2, an impedance conversion circuit 5-1 and the like, and is connected to the A / D port of the microcomputer 35 via the f terminal of the connector 6 (this voltage is hereinafter referred to as Vf).

In the above structure, when the voltage between Va and Vb is processed by the microcomputer as the signal of the infrared sensor, the variation of the output voltage of the constant voltage circuit, that is, the variation of the electronic parts can be absorbed, and it is superimposed on Vb. The noise can be ignored and the object to be heated can be accurately measured.

Next, another embodiment of the present invention will be described with reference to FIG. The thermopile 1 has a hot junction and a cold junction, that is,
It can be expressed as a function of the temperature of the object to be heated 13 (hereinafter referred to as To) and the case temperature of the thermopile 1. If the case of the thermopile 1 and the temperature sensor IC3 are thermally coupled 100%, the temperature of the case = temperature sensor IC3.
Therefore, the output voltage of the sensor can be expressed as (Va-Vb) = f (To, Ta) using the temperature of the object to be heated (hereinafter referred to as Ta). Theoretically, the law of Stefan-Boltzmann can be applied, but the emissivity of the object to be heated 13, the transmittance of the lens 10 and the radiant energy of the object to be heated by the cut filter provided in front of the thermopile 1. Deviates from Stefan-Boltzmann's law because is attenuated and limited. Therefore, data is sampled by a typical sensor unit, and the vertical axis (Va-
Vb), the horizontal axis is (To-Ta), and the parameter is T
It suffices to create a graph a and create a data table in the microcomputer 35 by dividing the graph within the range permitted by the ROM capacity of the microcomputer 35 and the resolution of temperature calculation. The data table of the microcomputer 35 is, for example, as shown in (Table 1). Ta is Ta = 100 × Ve according to the characteristics of the temperature sensor IC3.
In FIG. 5, three representative temperature ranges that the sensor unit can take (Ta = 10 ° C., 25 ° C., 50 ° C.) and the object to be heated 13
Typical temperature range of 3 points (To = -15 ° C, 35
Data were collected at ℃, 65 ℃) to calculate the empirical formula. In this example, when Ta = 10 ° C., (Va−Vb) = 400 × (To−T
a) / 40-100 At Ta = 25 ° C., (Va−Vb) = 400 × (To−T
a) / 40 Ta = 50 ° C. (Va−Vb) = 400 × (To−T
a) / 40 + 100. If the ROM capacity of the microcomputer is small, if Ta ≧ 25 ° C. (Va−Vb) = 400 × (To−T
a) / 40 + 100 (Ta-25) / 25 Ta <25 [deg.] C. (Va-Vb) = 400 * (To-T)
a) / 40 + 100 (Ta-25) / 15, an approximate expression may be prepared and used instead of the ROM table.

In the above structure, estimating the temperature of the object to be heated by the software processing of the microcomputer acts so as to reduce the electronic parts of the sensor circuit, the product can be made compact, and the cost of the product can be reduced. The effect is that you can do it.

Another embodiment of the present invention will be described with reference to Table 2 below. Since there are variations in lenses, electronic components, etc., the temperature conversion formula is not common to all sensor units, so correction is made as follows. 1 of FIG.
The change in the output value of the thermopile 1 with respect to the change in the temperature of the measurement object, that is, (Va-Vb) / (Ta-Tb) includes the semi-fixed resistance 2-
If adjusted in advance in step 2, the inclination (v / deg) can be corrected. However, since the zero point has not been corrected,
It is examined how much the deviation from the reference sensor unit is, and the temperature calculation formula is corrected based on the value.
For example, in FIG. 5, (Ta, To) = (25 ° C., 35 ° C.)
The output voltage of the standard sensor unit is 100mv,
When the output voltage of a certain sensor unit is 150 mv, the semi-fixed resistor 5-2 of the correction circuit 5 is adjusted to store the information of 50 mv. On the other hand, the graph of FIG. 5 shifts itself by 50 mv in the y-axis direction, and the data table of the microcomputer 35 is as shown in FIG. Based on the above configuration, as the operation of the microcomputer 25, the information of 50 mv combined by the semi-fixed resistor 5-2 of the correction circuit 5 is read when the microcomputer 25 is reset, and this value (here, 50 mv) is read. Accordingly, the data table is uniformly shifted from (Table 1) and changed as shown in (Table 2), and the temperature of the article to be heated 13 is calculated.

In the above-mentioned configuration, the information of the correction circuit acts to correct the characteristics of the sensor units having different characteristics, and the effect that the temperature of the object to be heated can be accurately measured even if the characteristics of the sensor units vary. is there.

[0021]

[Table 1]

[0022]

[Table 2]

In the above-mentioned embodiment, the magnetron 11 is used as the heating means, and the thermopile 1 is used as the infrared sensor.
The temperature sensor IC3 serves as the case temperature detecting means, the microcomputer 35 serves as the input means, the microcomputer 35 serves as the temperature calculating means, and the inverter 33 and the relay 3 serve as the controlling means.
4, the microcomputer 35, the correction circuit 5 as the correction means, and the constant voltage generation circuit 4 as the constant voltage power source, but of course, other methods may be used.

[0024]

As described above, according to the heating device of the present invention, the following effects can be obtained.

(1) Since the signal of the infrared sensor and the signal of the case temperature detection sensor are individually taken into the microcomputer and the temperature of the object to be heated is calculated by the microcomputer, the electronic parts of the sensor circuit are reduced, so the mounting area is reduced. Also, the product can be made compact and the product cost can be reduced.

(2) Since the variation in the characteristics of each sensor unit from the reference sensor unit is stored as correction information in the sensor circuit and the temperature of the object to be heated is calculated using the correction information, the sensor unit Even if the characteristics vary, the temperature of the heated object can be accurately estimated.

(3) Since the reference power source is provided in the sensor circuit and the sensor signal is processed based on the value, the variation of the circuit can be absorbed, the influence of noise is reduced, and the measurement accuracy is improved.

[Brief description of drawings]

FIG. 1 is a block diagram of a sensor circuit according to an embodiment of the present invention.

FIG. 2 is a side sectional view of a sensor unit according to an embodiment of the present invention.

FIG. 3 is a side sectional view of a heating device according to an embodiment of the present invention.

FIG. 4 is a block diagram of a control circuit according to an embodiment of the present invention.

FIG. 5 is a diagram showing the temperature of the object to be measured with respect to the output voltage of the sensor circuit of the heating device in the embodiment of the present invention.

FIG. 6 is a block diagram of a conventional heating device.

[Explanation of symbols]

 1 Thermopile 2 Amplification circuit 3 Temperature sensor 4 Constant voltage generation circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shunichi Nagamoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Takuo Shimada, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A heating means for heating an object to be heated, and an infrared sensor for detecting infrared rays emitted from the object to be heated,
Case temperature detecting means for detecting the case temperature of the infrared sensor, input means for individually taking in the signal of the infrared sensor and the signal of the case temperature detecting means, and for the infrared sensor taken in by the input means A heating device comprising a temperature calculation means for calculating an estimated temperature of the object to be heated using a signal and a signal of the case temperature detection means, and a control means for controlling the heating means based on the estimated temperature. 2. A heating means for heating an object to be heated, an infrared sensor for detecting infrared rays emitted from the object to be heated,
Case temperature detecting means for detecting the case temperature of the infrared sensor, temperature estimating means for estimating the temperature of the object to be heated using the signal of the infrared sensor and the signal of the case temperature detecting means, and the temperature A heating device comprising: a correction means for giving correction information to the estimation means; and a control means for controlling the heating means based on the estimated temperature corrected based on the information of the correction means. 3. The temperature estimating means includes an input means for individually taking in the signal of the infrared sensor and a signal of the case temperature detecting means, and a signal of the infrared sensor and the case temperature detection taken in by the input means. The heating device according to claim 2, further comprising: a temperature calculation unit that calculates the estimated temperature of the object to be heated by using a signal from the unit. 4. A heating means for heating an object to be heated, a constant voltage power source, and a constant voltage power source, which are provided on the same substrate, and are radiated from the object to be heated connected with the constant voltage power source as a reference. An infrared sensor for detecting infrared rays, a case temperature detecting means for detecting a case temperature of the infrared sensor, an infrared sensor signal based on the constant voltage power source, and a signal of the case temperature detecting means A heating device comprising a temperature estimating means for estimating the temperature of an object to be heated and a control means for controlling the heating means based on the estimated temperature. 5. The temperature estimating means includes an input means for individually taking in a signal from the infrared sensor, a signal from the case temperature detecting means and a voltage value of the constant voltage power source, and the infrared sensor taken into the input means. 5. The heating device according to claim 4, further comprising: a temperature calculation unit that calculates the estimated temperature of the object to be heated by using the signal of the above, the signal of the case temperature detection unit, and the voltage value of the constant voltage power supply.