JPH0228051B2 - HAKARIKINOOJUSURUKANETSUCHORIKI - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a heating cooker having a so-called weighing function, which is equipped with a function of measuring the weight of food. Structure of conventional example and its problems In conventional high-frequency heating of food, for example, in a microwave oven, as the weight of the food increases, the heating output and heating time required for heating increase almost proportionally. Therefore, food weight information is required to control heating output and heating time. From this point of view, many microwave ovens have been proposed that are equipped with a scale function and a high frequency output control function that operates in conjunction with the scale function. For example, a perspective view of a conventional microwave oven with a weighing function is shown in FIG. Fig. 2 shows a cross-sectional view of the microwave oven seen from the side. In other words, a load receiving stand 9 is installed on the upper surface of the microwave oven main body, and a part of the main body is configured to detect the weight in conjunction with the movement of the receiving stand 9. In FIGS. 1 and 2, reference numeral 9 denotes a loading platform on which food is placed in order to measure the weight of the food, and the weight of this loading platform 9 is transmitted to the leaf spring 11. FIG. 3a shows a sectional view of the microwave oven seen from the front, and FIG. 3b shows an enlarged view of the main part of the weight detection section. It has a structure in which two leaf springs 11 are arranged parallel to each other and fixed at both ends, and is called a Roberval mechanism. Therefore, the weight of the food is transmitted to the leaf spring 11, causing the leaf spring to deform. A load cell 2 is attached to the leaf spring 11 to detect the deformation of the leaf spring, and is capable of detecting minute changes in resistance value. Fourth
The figure shows the control circuit of a conventional microwave oven with a weighing function. Reference numeral 12 denotes a load cell, which is a part of the bridge, and when the leaf spring 11 deforms, a signal is generated as a voltage change between both terminals A-B in the middle of the bridge. 27 is a differential amplifier that amplifies this voltage and further transmits this voltage to the microcomputer 2.
A/D converter 26 to make the signal inputtable to 5.
use. Further, the correlation between the A/D converted level and the weight is stored in the storage section of the microcomputer 25, and the weight is detected based on this. As described above, in the past, the deformation of a leaf spring was detected as a minute resistance change by a load cell, voltage conversion, amplification, and A/D conversion were performed, and the weight of the food was detected through processing by a microcomputer. Therefore, the conventional weight verification method has the following problems. (1) To measure the weight, the food is placed on or around the top of the microwave oven. Considering the general usage conditions of cooking devices such as microwave ovens, this means that the top surface of the main body is not convenient for use because other items are placed on it, or it is close to the ceiling, hanging shelves, etc. In addition, it is a two-step operation in which the food is measured on the top surface of the microwave oven and then stored in the heating chamber, which is inefficient. (2) It is necessary to consider the stroke width required for the deformation of the leaf spring. (3) During food measurement, the leaf spring vibrates minutely, making the amount of deformation unstable and making accurate measurement difficult. (4) Since the amount of resistance change in the load cell is minute, a large amplification factor is required, and it is also easily affected by noise. (5) Resistance accuracy, amplifier, A/
Electronic components used in the D converter and the like need to be highly accurate. (6) Errors in electronic components such as bridges, amplifiers, and A/D conversion directly affect the measured word difference. (7) The cost is high because it is necessary to use high-precision parts. (8) Because errors in electronic components greatly affect measurement errors, adjustment means are required. Purpose of the invention The present invention solves the above-mentioned conventional problems.
The purpose of the present invention is to provide a heating cooker that has a weighing function that is easy to use while improving measurement accuracy. Structure of the Invention The present invention provides a door that is attached to the front opening of the heating chamber so that it can be opened and closed at the place where the food is placed in order to measure the weight of the food, thereby making it possible to achieve a product that is both easy to use and has an excellent appearance. do. In order to achieve this, we focused on the correlation between the frequency of a string of a certain length and the tension of that string, and by transmitting the weight of the food as tension to the string, we This method attempts to measure the weight of food by counting the amount of food. This time, it is possible to measure food by placing it on the door with the door open. When the door is opened, the force to keep it horizontal is transmitted as the tension of the string, and by measuring the frequency of the string, the weight of the food can be measured. Also, since the difference in the open/closed state of the door is caused by the difference in the frequency of the string vibration,
It is also possible to detect whether the door is open or closed. By doing this, the analog quantity of the weight of the food is converted into a digital quantity of the frequency by the string, eliminating the need for electronic circuits for A/D conversion and making it possible to use high-precision electronic components. High-precision electronic parts are no longer necessary. Therefore, the cost is low and measurement errors due to electronic components are eliminated. Furthermore, since amplifier circuits have conventionally amplified analog quantities, errors in the amplifier circuits directly become measurement errors. However, the amplifier circuit in the present invention is used only to amplify the digital quantity to a level that can be input to the microcomputer, and has nothing to do with measurement accuracy. Furthermore, since the weight is detected by the tension of the strings,
Unlike conventional spring deformation, there is no change in position or vibration, so there is no need to consider space for stroke width. Also, the weight applied to the door can be easily transmitted to the strings. FIG. 5 shows the principle of weight measurement according to the present invention. Figure a shows the vibration when a weight m1 is attached. The frequency F of the vibration string 16 at this time is

[Formula] becomes. However, T is the tension, L is the length of the vibrating string, and C is a constant. Figure b shows the principle of measuring the sum of the weights of two objects. The weight of m2 and m3 is weight transmission string 1
5 and pulley 31 to one place, vibrating string 1
The tension is set to 6. This method therefore makes it possible to concentrate the weight in one place as shown in FIG. DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 6 is a perspective view of a microwave oven with a scale function as an embodiment of the present invention, showing a state in which the door 3 is opened. 1 is a display section for displaying the heating time and heating output; 2 is a setting section with keys for setting the heating time and heating output as well as instructing the start and stop of cooking; This is a door that can be opened and closed to allow entry and exit. 5 is a main body, 6 is food, and 7 is a placing plate on which food 6 is placed. Reference numeral 13 is a door arm which serves to keep the door 3 horizontal and to transmit the weight of the door 3 and the food 6 placed thereon. Reference numeral 17 denotes a door support fitting that serves as a fulcrum when the door 3 is opened and closed. Reference numeral 34 denotes a placement position indicating mark on the top surface of the door 3 that indicates the position where the food 6 is placed. FIG. 7 shows a cross-sectional view of the microwave oven when viewed from the side. 8 is a magnetron for generating high frequency output. Freeze foods 6 are placed on a placing tray 7, and these are further placed on a door 3 which is opened horizontally. Then, the weight of the door 3 is supported by the door support fitting 17 and the door arm 13. Further, since the position at which the food 6 is placed on the door 3 is indicated, the ratio of the weights applied to the door support fitting 17 and the door arm 13 is approximately constant. Reference numeral 33 denotes a door spring that functions to pull the door 3 toward the heating chamber to ensure that the door 3 closes when it is closed. 14 This is a weight transmission bar on which the weight of the door arm 13 is applied, and is pulled by a weight transmission string 15 so that the door 13 is held horizontally. In order to show this situation in detail, the main configuration related to weight measurement is shown in FIG. door arm 1
3. The weight sequentially applied to the weight transmission bar 14 and the weight transmission string 15 is collected at one point using a pulley 31 or the like, and concentrated on the vibrating string 16. That is, the weight of the food 6 is divided by the door arm 13 and the door support fitting 17 at a substantially constant ratio,
Among them, the weight applied to the door arm 13 is the vibration string 1.
This results in a tension of 6. However, door spring 33
Since the pulling force of is known in advance, it is necessary to compensate for this amount. And this vibration string 1
There is a correlation between the frequency of vibration 6 and tension, and the weight of food 6 can be measured by counting this frequency. The frequency of the string is detected by a microphone 18. On the other hand, it is necessary to give vibration to the strings. Reference numeral 19 denotes a string playing means, which acts to play the string during measurement. In FIG. 9, 18 is a microphone for detecting the frequency of the vibration string 16, and 19 is string playing means. The coil attracts the flipping weight 32, and when the current in the coil is cut off, the flipping weight 32 uses its momentum to flip the vibrating string 16. Figure 10 shows the electric circuit of a microwave oven. 25
is a microcomputer that plays a central role in control and has functions such as storage, calculation, judgment, and input/output control. The microcomputer 25 performs the following processing during weight measurement. Figure 11 shows microcomputer 2.
5 is shown. The frequency of the vibration string 16 is inputted from the input _I5 and counted by the counter section (101). On the other hand, two correlations are stored in the storage section of the microcomputer 25, one of which is the correlation between vibration frequency and weight, and the weight is determined from this (102). Then, based on the weight, the heating output and heating time are determined based on another correlation between the weight and the heating time and heating output (103). Based on this, the heating output is controlled by the outputs O ₁ to O ₂ (104). As described above, according to this embodiment, the place for measuring the weight of food is the door 3 attached to the front opening of the heating chamber 4 so as to be openable and closable, thereby making it possible to achieve ease of use and an excellent appearance. . Furthermore, it is very easy to transmit the weight applied to the door 3 using the transmission string and collect it in one place. Furthermore, since the measurement structure does not utilize deformation or the like, there is no need to consider the stroke amount for displacement, and vibrations of the spring are completely irrelevant. Furthermore, by converting the vibrations of the string into analog quantities that are correlated to the weight, and counting the vibrations using the counter section of the microcomputer, the frequency as a digital quantity can be obtained.
No electronic circuit is required for D conversion. Also, A/D
High-precision electronic components for conversion are no longer required. Conventionally, amplifier circuits amplified analog quantities, so errors in the amplifier circuits were directly generated as measurement errors. However, the amplifier circuit of the present invention only converts digital quantities into a state that can be input to a microcomputer, and has nothing to do with measurement accuracy. Effects of the Invention As described above, according to the present invention, the following effects can be obtained. (1) The weight of the food can be measured by placing it on the door when the door is opened, providing excellent operability. (2) The weight applied to the door can be easily transmitted to the weight detection unit. (3) Since this measurement method does not utilize deformation, there is no need to consider strokes for deformation. (4) Since weight is converted into frequency using a vibrating string, no electronic circuit is required for A/D conversion. (5) Since A/D conversion is not required, measurement errors due to that circuit do not occur. Also, electronic parts are not required. (6) Since A/D conversion is performed by the vibrating string, errors in the amplifier circuit, etc. after the frequency of vibration do not constitute measurement errors. Therefore, the cost is also low.

[Brief explanation of drawings]

Figure 1 is a perspective view of a conventional microwave oven with a scale function.
Figure 2 is a cross-sectional view of the same microwave oven as seen from the side;
Figure a is a sectional view of the microwave oven seen from the front, Figure 3 b is an enlarged view of the main parts for weight detection, Figure 4 is a control circuit diagram of the microwave oven, and Figures 5 a and b are the main parts. An explanatory diagram of the principle of weight detection according to the invention, FIG. 6 is a perspective view of a microwave oven with a weighing function according to an embodiment of the invention with the door open, and FIG. 7 is a cross-sectional view of the same microwave oven as seen from the front. , Figure 8 is a configuration diagram of the main parts for detecting the same weight, Figure 9 is a configuration diagram of the frequency detection section, Figure 10 is a control circuit diagram of the microwave oven, and Figure 11 is for explaining the operation. This is a flowchart. 1...Display section, 2...Setting section, 3...Door, 4
... Heating chamber, 5 ... Main body, 6 ... Food, 7
... Placement plate, 8 ... Magnetron, 9 ... Loading platform, 10 ... Leaf spring type weight detection section, 11 ... Leaf spring, 12 ... Load cell, 13 ... Door arm,
14... Weight transmission bar, 15... Weight transmission string, 1
6... Vibration string, 17... Door support metal fittings, 18...
Microphone, 19... String playing means, 20... High voltage transformer, 21... High voltage capacitor, 22...
Power relay and its drive circuit, 23... High voltage relay and its drive circuit, 24... Door switch, 25... Microcomputer (microcomputer),
26...A/D converter, 27...Differential amplifier, 2
8...Fan motor, 29...Voltage adjustment waveform shaping, 30...Amplification waveform shaping circuit, 31...Pulley, 32...Repelling weight, 33...Door spring, 3
4...Placement position indication mark.

Claims (1)

[Claims] 1. A heating chamber that stores food as an object to be heated;
a heating means for supplying thermal energy to the heating chamber; a door that can be freely opened and closed by rotating around a hinge located at the lower front of the front opening of the heating chamber; and maintaining the door substantially horizontally when the door is opened. In order to fix the door arm that supports the door and one side,
A vibrating string whose frequency changes by applying tension to the other end, a string playing means for generating vibration in the vibrating string, and a force applied to the vibrating string via the door arm to keep the door horizontal. A weight transmission string is connected to the vibration string so that the force transmitted and kept horizontal becomes the tension of the vibration string, and a counter unit that counts the frequency of the vibration string and a correlation between the frequency and the weight are provided. A heating cooker having a weighing function, which is equipped with a microcomputer having a storage section that stores correlations between weight, heating time, and heating output, and an output section that controls a heating means based on the contents of the storage section. 2. The heating cooker having a scale function according to claim 1, which is configured to indicate the placement position of the food by a mark written on the door when the door is opened. 3. A heating cooker having a scale function according to claim 1, which is configured to detect the open/closed state of the door by a change in the frequency of the string.