JPS6064133A - Cooker equipped with weight sensor - Google Patents

Abstract

PURPOSE:To simplify the adjustments of the weight sensor and a sensor circuit remarkably by a method wherein a memory unit, memorizing the output of the weight sensor under a condition that it is not weighed, is provided to change the amplifying degree of the sensor circuit in accordance with a difference between the content of the memory unit and the output of the weight sensor under a condition that a reference weight is weighed thereon. CONSTITUTION:A micro-computer 20 monitors the change of output of an amplifying degree switching circuit 60 by the output of an A/D converter 70 and compares the output with a reference weight output V, which is memorized previously, when the output of the amplifying degree switching circuit 60 is changed by putting the reference weight on a shelf board 1. Then, the micro-computer 20 puts ON signals F, G, H, I selectively and switches the amplifying degree of a positive phase amplifier 65 in the amplifying degree switching circuit 60 so that said output becomes the reference weight output V. That means the amplifying degree is switched indirectly. Thus, the adjustments of the weight sensor 3 and the sensor circuit 4 are finished. The data of adjusting process are memorized into the nonvolatile memory of the micro-computer 20 or ROM, for example, and the after processing work for adjustment becomes unnecessary.

Description

[Detailed description of the invention] [Technical field of invention] The present invention is a method for detecting the stumbling block of food to be cooked.

The present invention relates to an adjuster with an MM sensor equipped with a quantity sensor.

[Technical background of the invention and its problems]

One example is shown in Figure 1. In Figure 1, 1
is a side plate on which the food to be cooked is placed, and is provided in the heating chamber (not shown). The shelf board 1 is supported by a shaft 2, and the lower end of the shaft 2 contacts the weight sensor 3. In other words, when the food to be cooked is placed on the shelf board IK, its mass is connected to the M and ft sensor 3 via the shaft 2. Therefore, the minute output of the weight sensor 3 is It is amplified by the sensor circuit 4 and the main 11tll Ill
t'ilis. This main control section 5 has a microcomputer, detects the weight of the food to be cooked according to the output of the sensor circuit 4, and controls cooking according to the detection result. Incidentally, an operation section 6 for setting cooking conditions and a display section 7 for displaying various information are connected to the main control section 5. On the other hand, is 8 an AC? IT
, a, this power supply 8 has a main control section 50 control switch 9.
A magnetron 1), which is a high frequency generator, is connected via a high voltage transformer 10 and the like.

It is something that will be provided.

Here, details of the weight sensor 3 and sensor circuit 4 are shown in FIG. 2. First, the weight sensor 3 is connected to the excitation power source 12, and is constructed by assembling a strainer whose resistance value changes according to strain into a bridge. When a weight is applied to the weight sensor 3, an unbalanced voltage corresponding to the weight is produced in the bridge, which is taken out as an output. On the other hand, the sensor circuit 4 includes a first stage amplifier 13゜3, a resistor R□
, It, , R2, a next stage amplifier 14, etc., and amplifies the output of the superposed sensor 3 with an amplification degree determined according to the values of the resistors RI + n, IR.

By the way, in such a microwave oven, when there is no food to be cooked on the shelf board 1, the weight sensor 3 must be balanced and the unbalanced voltage must be 0''. The pressure must be 0# when no food is placed on the output.

That is, as shown in FIG. 2, it is normal for the output of the sensor circuit 4 to vary as shown by line A in the diagram depending on the weight of the food to be cooked, but in reality, the output of the sensor circuit 4 changes as shown in line A. Due to variations and deviations in the amplification degree of the sensor circuit 4, the output of the sensor circuit 4 becomes as shown by line B or line C in the figure, and if left as is, an error will occur in weight detection.

To deal with i'LK, conventionally, the excitation power supply 12 was adjusted to balance the bridge of the weight sensor 3, and the resistance of the sensor circuit 4 (1゜''4 + R2 was made into a variable resistance. At the same time, it was necessary to change the amplification degree of the sensor circuit 4 by adjusting its resistance value.

However, this has the disadvantage that the adjustment work takes time, resulting in a decrease in productivity and a concomitant increase in costs. Furthermore, if the resistors RI+R2 and R2 are variable resistors, errors may occur due to mechanical contact failure, and there is room for improvement in terms of accuracy.

[Purpose of the invention]

This invention was made in view of the above-mentioned 4F circumstances, and its purpose is to greatly simplify the adjustment of weight sensors and sensor circuits, thereby improving productivity and reducing costs. It is an object of the present invention to provide a highly reliable cooking appliance with a weight sensor that enables weight reduction and also improves the accuracy of adjustment.

[Summary of the invention]

In this invention, a storage section is provided for storing the output of the M quantity sensor in a state in which no person is placed on the vehicle, and the sensor circuit is configured to operate according to the difference between the contents of this storage section and the output of the weight sensor in a state in which a reference weight is applied. The sensor circuit is adjusted electronically by providing means for changing the amplification degree of the sensor circuit.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. However, in the drawings, the same parts as in FIGS. 1 and 2 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

First, the overall configuration is the same as in FIG.

is a microcomputer 20. Signal storage section 30, subtraction circuit 50. Amplification switching circuit 60°A/1) (analog/
It consists of a digital) converter 70. Signal storage unit 30
is a field effect transistor 3 which takes in the output of the sensor circuit 4 according to the rσ signal from the microcomputer 2Q.
2. A capacitor 34 to which the signal taken in by the transistor 3 is applied via a voltage follower (amplification degree of 9.1") 32 and a diode 33; and a voltage follower 35 that outputs the heavy pressure across the capacitor 34 to the outside. , the output terminal of this voltage follower 35 is grounded according to the signal E from the microcomputer 20.
It consists of 11 field effect transistors 36 and the like. Subtraction circuit 5
0 subtracts the contents of the signal storage unit 30 from the output of the sensor circuit 4 and outputs a signal at a level corresponding to the subtraction result.
0 includes a positive-phase amplifier 65 having a plurality of feedback resistors 61, 62° 63.64, and field effect transistors 66, 67.6 that respond to the signals F, G, H, and I, respectively.
8.69, it will be thrown in as appropriate.

That is, the output of the subtracting circuit 50 is amplified with an amplification degree corresponding to the closed state of each feedback resistor, and by switching this amplification degree, the amplification degree of the sensor circuit 4 is indirectly changed.

Next, the operation of the above-mentioned implantation will be explained with reference to the flowchart of FIG. 5.

First, nothing is placed on the shelf board 1, and the control unit mL operation is set using the operation unit 9. Then, the microcomputer 20 turns on the E signal, turns on the transistor 36, and discharges the °C capacitor 34.

In other words, the stored contents of the signal storage section 30 are reset. Next, the microcomputer 20 turns on the D signal at the same time as turning on the E signal, turns on the transistor 3, and applies the output of the sensor circuit 4 to the capacitor 34.

After that, the microcomputer 20 turns off the D signal.

As a result, the capacitor 34 is charged to 71! The output of the sensor circuit 4 in a state where no weight is applied to the mouse sensor 3tlC is stored in the signal storage section 30. In this case, the contents of the signal storage section 30 are the output II OII in FIG.
It will be equivalent to a point trap.

When an object is placed on the shelf l in this state, a signal corresponding to the amount of M is output from the sensor circuit 4.

Then, a signal with a level corresponding to the difference between the output of the output circuit 4 and the content of the i storage section 30 is outputted from the 3'4 2 circuit 50. This output is amplified by the amplification switching circuit 60. The signal is then converted into a digital signal by the Mv converter 70 and supplied to the microcomputer 2 (7).

Claims (1)

[Claims] In a cooking appliance with a weight sensor that has a weight sensor that receives the weight of food to be cooked and a sensor circuit that amplifies the output of this weight sensor, and that automatically cooks food by detecting the weight of the food to be cooked from the output of this sensor circuit. , the above with no weight applied,! t1. A storage section for storing the output of the weight sensor, and means for changing the amplification degree of the sensor circuit in accordance with the difference between the contents of the storage section and the output of the weight sensor in a state where a reference quantity is applied. M precision sensor-adjusted J! 1! vessel.