JPH04155122A - Electronic control device - Google Patents

Abstract

PURPOSE:To perform accurate drive and control of a load by correcting a digital signal even when a conversion error is produced during conversion of an analogue signal, being an output from a sensor to detect the state of a part to be detected, into a digital signal by means of a converter. CONSTITUTION:A microcomputer 5 drives a magnetron 3 and executes microwave heating. A converter 7 converts a first given voltage VS1 from a first given voltage generator 8 into a digital signal Ma corresponding to a first given voltage, and a converter 7 converts a second given voltage VS2 from a second given voltage generator 9 into a digital signal Mb corresponding to a second given voltage. The converter 7 converts an analogue signal IR from a temperature sensor 4 into a sensor corresponding digital signal M. A conversion error occurs to the digital signals Ma and Mb corresponding to first and second given voltages and the sensor corresponding digital signal M during conversion by the converter 7 and are displaced from first and second given digital values Na and Nb to which no conversion error occurs. By correction of displacement of the sensor corresponding digital signal M, the conversion error of the sensor corresponding digital signal M is eliminated. The magnetron 3 is driven and controlled according to a correction value to heat a food to a desired state.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an electronic control device that detects the state of a detected part using a sensor and controls the drive of a load.

(b) Conventional technology In an electronic control unit that has a sensor that detects the state of the detected part, the sensor output is an analog signal, so this analog signal is converted to a digital signal by an A/D converter, and the The load is driven and controlled based on the signal (see Mochikoi No. 2-19377).

However, as is well known, this A/D converter consists of a large number of resistors, and variations in each resistor overlap, resulting in conversion errors, which may make it impossible to drive and control the load based on accurate digital signals. be.

(c) Problems to be Solved by the Invention The present invention provides an electronic control device that can accurately drive and control a load even if a conversion error occurs when an analog signal of a sensor output is converted into a digital signal by a converter. That is.

(d) Means for Solving the Problems The electronic control device of the present invention includes a sensor that detects the state of the detected part and outputs an analog signal according to the state, and first and second predetermined voltage generating means. Conversion that converts an analog signal from the sensor into a digital signal compatible with the sensor, and converts first and second predetermined voltages from the first and second predetermined voltage generating means into digital signals compatible with the first and second predetermined voltages. a correction means for correcting the sensor-compatible digital signal based on the deviation of the first and second predetermined voltage-compatible digital signals converted by the converting means from the first and second predetermined digital values; and control means for driving and controlling the load based on the corrected output of the means.

(e) If an error occurs in the conversion by the action conversion means, the first and second
The first and second predetermined voltage corresponding digital signals obtained by converting the first and second predetermined voltages from the predetermined voltage generating means deviate from the first and second predetermined digital values, and based on this deviation, the analog signal from the sensor is generated. The sensor-compatible digital signal obtained by converting the sensor is corrected by the correction means, and the load is driven and controlled based on this correction value. Therefore, even if a conversion error occurs,
Accurate drive control of the load is achieved.

(F) Embodiment FIG. 1 shows the structure of an electronically controlled microwave oven which is an embodiment of the electronic control device of the present invention. Microwaves are supplied from a load, ie, a magnetron 3, through a waveguide 2 into a heating chamber 1 in which food is stored, and microwave heating of the food is performed within the heating chamber 1. On the other hand, an infrared temperature sensor 4 is provided at the upper part outside the heating chamber 1. This temperature sensor uses microwave-heated food as the detected part, and detects the food temperature (heated state of the food) by receiving infrared rays generated from the food, and outputs an analog signal corresponding to this temperature. Output.

FIG. 2 shows the circuit of the microwave oven. A microcomputer 5 is provided to control the microwave oven. This microcomputer inputs operation key information from a keyboard 6 provided on the front side of the microwave oven body, and also receives an analog signal IR corresponding to the food temperature from the temperature sensor 4 using a built-in A/D converter 7. At the same time, the first and second predetermined voltages VSI VS2 are input from the first and second predetermined voltage generators 8.9. The microcomputer 5 drives and controls the magnetron 3 based on this input information.

The first predetermined voltage generator 8 has two resistors 10 and 11 connected in series, and one resistor IO side is connected to the DC voltage VD.
D and the other resistor 11 side is grounded, and the DC voltage VDD is applied from the connection point of both resistors 1O111.
The first predetermined voltage VS1 obtained by dividing the voltage is output. The second predetermined voltage generator 9 also has two resistors 12.13,
It has a similar configuration, and outputs the second predetermined voltage VS2 from the connection point between both resistors 12 and I3.

As is well known, the conversion S7 is composed of a large number of resistors, converts the analog signal IR from the temperature sensor 4 into an 8-bit digital signal M corresponding to the sensor, and converts the analog signal IR from the temperature sensor 4 into an 8-bit digital signal M corresponding to the sensor
First and second predetermined voltages VS from the predetermined voltage generator 8.9
I, VS2 are converted into 8-bit digital signals Ma, Mb corresponding to first and second predetermined voltages. The sensor-compatible digital signal M and the first and second predetermined voltage-compatible digital signals Ma and Mb thus converted are provided for control by the microcomputer 5.

Thus, in the first predetermined voltage generator 8, the first predetermined voltage generator 8
The predetermined voltage VSI is expressed by the first equation.

VS1=VDDXR2/(R1◆R2) -...
-・-= (1) R1 and R2 are each the above resistance 1O11
It represents a resistance value of 1.

Here, if the resistor l0111 is selected to be easily available with a tolerance of 1% between the resistors iR1 and R2,
Maximum value VSIMAI and minimum value V of the first predetermined voltage VSI
S1wIw is expressed by the second and third equations.

VSIMAx=VDDX1.01R2/(0,99R1
"1. QIR2) - (2) VSl, , , = VDDX
O,99R2/(1,0IR1+0.99R2)...
(3) The fourth equation is the maximum value vSIMA! and the variation width (VSI, AI-VSIMIN) of the first predetermined voltage VSI based on the minimum value VSIM.

VDDXl, 01R2/(0,99R1+1.0IR
2) -VDDXo, 99R2/(1,01R1+0.9
9R2)-(4) On the other hand, if the digital signal converted by the converter 7 has an 8-pin configuration, and the DC voltage VDD is also the power supply voltage of the converter 7, then the voltage per pin is expressed by the fifth equation. It will be as follows.

VDD/2”・・・・・・・・・・・・・・・
(5) In this case, if the fourth equation indicating the variation width of the first predetermined voltage VSI is smaller than the fifth equation, the converter 7
Errors caused by variations in the first predetermined voltage VSI do not occur in the digital signal corresponding to the first predetermined voltage that is converted by the first predetermined voltage VSI.

Now, assuming that the resistance value R1 is twice the resistance fuiR2, the relationship between the fourth equation and the fifth equation is expressed by the sixth equation.

1,01/(+1.01 to 0,99) -0,99/
(+0.99 to 1,01) < 1/256...
(6) When finding K that satisfies this equation, the solution to equation 7 is obtained.

K>8.12, K<0.1232...
・・・・・・・・・(7) Here, the partial pressure ratio R2 of the above first equation
/(R1+R2), by applying K in the seventh equation so that the voltage division ratio is less than 11% or greater than 89%, an error caused by the variation in the first predetermined voltage ~ S1 occurs. I try not to.

The same applies to the second predetermined voltage VS2.

Specifically, for the first predetermined voltage VSI, the voltage division ratio is set to be less than 11%, and for the second predetermined voltage VS2, the voltage division ratio is set to be greater than 89%.

On the other hand, the converter 7 is made up of a large number of resistors, and variations in each resistor overlap to cause a conversion error. Therefore, the magnetron 3 cannot be accurately driven and controlled based on the food temperature.

In order to accurately drive and control the load based on the food temperature even if a conversion error occurs, the microcomputer 5 performs control using the first and second predetermined voltages VSI and VS2 as described below. conduct.

FIG. 3 shows the flow of the main part of the control program related to such control, which is incorporated into the microcomputer 5. As shown in FIG.

When the desired heating temperature is set and the start of heating is instructed by the key operation information from the keyboard 6, the microcomputer 5 starts driving the 7-danetron 3 in step S1 and executes microwave heating.

Next, the microcomputer 5 S2, S3, S
4. Execute steps S5 in sequence. In step S2,
The first predetermined voltage VSI from the first predetermined voltage generator 8 is converted into a first predetermined voltage corresponding digital signal l1la by the converter 7.
Convert to In step S3, the second predetermined voltage VS2 from the second predetermined voltage generator 9 is converted to a second predetermined voltage by the converter 7.
It is converted into a digital signal 1Ilb corresponding to a predetermined voltage. In step S4, the analog signal I from the temperature sensor 4 is
A converter 7 converts R into a sensor-compatible digital signal N). the first and second predetermined voltage-compatible digital signals Ma;
A conversion error occurs in Mb and the sensor-compatible digital signal (2) in the conversion by the converter 7.

Here, in a state where no conversion error occurs in the converter 7, the first
and the second predetermined value is VSI, and the first value when converting y52.
and the second predetermined digital value Na1. Nb (predetermined), the first and second predetermined voltage corresponding digital signals Ma and Mb are deviated from the first and second predetermined digital values Na and Nb due to a conversion error. FIG. 4 shows these first and second predetermined voltage corresponding digital signals 1Ila,
1Ilb and the first and second predetermined digital values Na, Nb are shown. Referring to this figure, when the sensor-corresponding digital signal M is corrected according to equation 8 in consideration of the deviations described above, the conversion error in the sensor-corresponding digital signal M is eliminated.

N represents a sensor-compatible digital signal in which the conversion $ difference has been eliminated by correction.

Thus, step S5 corresponds to the correction means of the present invention, and in this step, the sensor-compatible digital signal N corrected according to the eighth equation is obtained.

The microcomputer 5 then executes step S6 and determines whether the correction value N, that is, the food temperature has reached the set cooking temperature. In this case, - microcomputer 5
If it is determined that the goal has not been reached: repeat steps 4 and onwards,
On the other hand, when the arrival judgment is completed, S7 corresponds to the control means of the present invention.
Go through the steps. In the same step, magnetron 3
The heating is controlled to stop the heating, and the microwave heating is terminated.

In this way, even if an error force occurs in the conversion by the converter 7, the error is corrected and the magnetron 3 is driven and controlled according to the correction value, so the magnetron 3 can be driven and controlled accurately according to the food temperature. Food can be heated to the desired state.

(G) Effects of the Invention According to the present invention, even if a conversion error occurs when an analog signal of a sensor output that detects the state of a detected part is converted into a digital signal by a converter, the C digital signal is corrected. Since this is made possible, the load can be accurately driven and controlled according to the state of the detected part, and a practical electronic control device can be provided.

[Brief explanation of the drawing]

The drawings relate to a microwave oven according to an embodiment of the present invention, in which Fig. 12 is a sectional view, Fig. 2 is a circuit diagram, the third leap is a flowchart of the control program, and Fig. 4 is a converter of an A/D converter. 5 It is a sexual figure. 4...Temperature sensor, 5...Microcomputer,
Power 7... A/D converter, 8... First predetermined voltage generator, 9... Second predetermined voltage generator.

Claims (1)

[Claims] (1) A sensor that detects the state of the detected part and outputs an analog signal according to the state, first and second predetermined voltage generating means, and converts the analog signal from the sensor into a digital signal compatible with the sensor. , converting means for converting the first and second predetermined voltages from the first and second predetermined voltage generating means into digital signals corresponding to the first and second predetermined voltages, and the first and second predetermined voltages converted by the converting means. 2. A correction means for correcting the digital signal corresponding to the sensor based on the deviation of the digital signal corresponding to the predetermined voltage from the first and second predetermined digital values, and a control means for controlling drive of the load based on the correction output of the correction means. Electronic control unit with.