JPH0635962B2 - Fruit and vegetable maturity determination device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for nondestructively measuring the maturity of fruits and vegetables such as melons, apples and watermelons.

(Prior Art) A sound is produced when an object is hit. This is because the object vibrates at a certain frequency. If the size of the object is constant, the frequency is higher as it is harder and lower as it is softer. Further, if the hardness is constant, the larger the size of the object is, the lower it is, and the smaller it is, the higher it is. Therefore, for example, as the maturity of the melon progresses, the pulp becomes softer and the natural frequency of the melon decreases, so that the maturity of the melon can be determined by measuring this. The difference due to the size of the melon can be corrected by measuring the diameter and weight of the melon. Although a non-destructive test method for the hardness of fruits and vegetables is not yet established, the method used at the laboratory level using the above fact is that the fruits and vegetables are beaten with a pendulum to generate the vibration noise. Is measured by a microphone and converted into a voltage, and the natural frequency of the object is determined from the spectrum obtained by performing a fast Fourier transform on the waveform, and the hardness is determined by the Food Research Institute of the Food Research Institute of the Ministry of Agriculture, Forestry and Fisheries. Published on November 18, 1985-Commentary-Non-destructive analysis and measurement method for food quality components (p39-44).

(Problems to be Solved by the Invention) However, the conventional nondestructive ripeness determination apparatus for fruit and vegetables has the following inconveniences and has room for improvement.

() Since the pendulum is used to strike, the strength to strike is not constant and reproducibility is poor.

() When used by an unskilled person at a fruit vegetable sorting shop or at a fruit store, the judgment varies widely.

() Accurate data cannot be obtained when measuring at a noisy store, etc., because unnecessary sound is picked up in addition to the signal.

() If the distance between the microphone and the melon changes, the magnitude of the signal picked up by the microphone differs, which makes the subsequent signal processing troublesome. Also, it is troublesome to adjust the distance between the melon and the microphone each time the size of the melon changes.

() Since the frequency of an object that is struck when it is struck depends on its size and hardness, the size of that object must be considered in order to determine more accurate hardness (maturity).
No consideration has been given to this point.

() Since the fast Fourier transform is used for frequency analysis, it is expensive.

There were various problems such as.

(Means for Solving Problems) The present invention solves the above problems and provides an apparatus that can be easily operated by an unskilled person and the determination of the ripeness of fruit and vegetables can be reliably and stably obtained. This is a cheap fruit to be measured and is made of an elastic material such as rubber or synthetic resin on the upper opening of the case body with a built-in microphone that catches the vibration wave generated when hitting the fruit or vegetables to be measured. When a measurement table is installed on the table, the passage leading to the microphone provided on the table is closed and the case body is configured to be substantially sealed. A sound collection device, an electric tapping device that is controlled to hit the measurement fruits and vegetables with a predetermined strength, and a frequency measurement circuit that calculates the frequency from the cycle time of the vibration wave captured by the microphone. The frequency A display device for displaying was provided to measure the maturity of the fruit and vegetables, and the sound collecting device was installed on an electronic scale for measuring the weight of the fruit and vegetables, and the measured fruit and vegetables were prescribed. Electric tapping device controlled to hit with strength, frequency measurement circuit that calculates the frequency from the cycle time of the vibration wave captured by the microphone, and the frequency determined by the frequency measurement circuit, the weight A frequency correction circuit is provided for correcting the frequency based on the difference between 1 and 2, so that the difference in ripeness caused by the difference in weight is corrected so that the ripeness of fruits and vegetables can be known more accurately.

(Operation) When the fruits and vegetables to be measured are placed on the placing table of the sound collecting device and tapped with the tapping device, the vibration wave is captured by the microphone installed in the case body. Then, the vibration wave is amplified, the degree of maturity is measured by the frequency measuring circuit, and displayed by the display device. In addition, a sound collecting device was installed on the electronic weighing machine for measuring the weight of fruits and vegetables, and the frequency signal obtained by the frequency measuring circuit was used to determine the frequency of vibration based on the difference in weight. In the case where the frequency correction circuit for performing the correction is provided, the frequency based on the difference in the weight of the fruit and vegetables to be measured is corrected, so that the ripeness of the fruit and vegetables can be measured more accurately.

(Example) Hereinafter, one example in which melon is used as a sample of fruit and vegetables to be measured will be described. 1 is a box-shaped case main body 2 having an opening 3 at the top, and a microphone 4 is installed in the case main body 2.
A sound collecting device provided with a mounting table 5 made of an elastic material such as rubber or synthetic resin having a curved supporting surface on which a sample to be measured is mounted and a passage 6 communicating with a microphone is provided on an opening 3 part. When the sample (melon) M to be measured is placed on the mounting table 5, the upper part of the passage 6 leading to the microphone 4 is closed by the melon M, and the case body 2 is configured to be substantially sealed. ing.

When the melon M is tapped with an electric tapping device 7 described later, the melon vibrates at a natural frequency determined by its size and hardness. The vibration waveform has an attenuation sine waveform as shown in FIG. The case body 2 has a closed structure with no opening other than the passage 6 so that the microphone 4 does not catch any sound other than the vibration sound of the melon M, and uses a material having a high sound insulation effect (for example, metal such as iron). There is. In this way, the signal-to-noise ratio (S /
The vibration waveform having a good N ratio) is amplified by the amplifier 8 to a level at which the subsequent signal processing is easy, and the vibration is measured by the frequency measurement circuit 9 which calculates the frequency from the cycle time of the vibration waveform shown in FIG. The number is measured and displayed on the display device 10 to determine the ripeness (hardness) of the fruit and vegetables, that is, the eating period. FIG. 3 is a plot of the natural frequencies of three melons (samples) M having significantly different sizes against the number of days of storage. In any melon, the natural frequency decreases with the number of days of storage and becomes soft. You can see that it will be ready to eat. However, as is clear from FIG. 3, the larger the melon, the smaller the natural frequency becomes when viewed for the same number of storage days.
By the way, since the natural frequency of the melon is almost inversely proportional to its diameter, the melon is weighed and the diameter is proportional to the cube root of the weight, so that the difference due to the size of the melon can be corrected. In order to detect the maturity more accurately, the sound collector 1 is installed on the electronic balance 11 and the weight of the melon is measured. The frequency signal obtained by the frequency measurement circuit 9 is measured by the weight signal, When blotted after passing through a frequency correction circuit 12 that corrects the frequency based on the difference in weight, the hardness error due to the difference in weight was remarkably improved as shown in FIG. Next, the tapping device shown in FIG. 1 showing one embodiment of the electric tapping device 7 will be explained. Two coils 14, 14 'are wound around the outer circumference of a bobbin 13 made of a non-magnetic material such as plastic, and a sample is prepared. (Melon) M is inserted into the bobbin 13 by inserting a rod 15 made of a magnetic material such as soft iron having a large sphere 15 'at its tip end that abuts the melon so as not to damage it.
Charged to 6, 16 'and connected to the coil 14,
When one of the switches 17 is turned on and a current is passed through the coil 14, the rod 15 is drawn up to the center of the coil 14 and immediately pops out to the left due to inertia, hits the melon M, and moves to a position slightly displaced to the right to stop. After the rod 15 hits the melon, when the other switch 17 'connected to the coil 14' is turned on, the rod 15 is pulled toward the right side toward the center of the coil 14 ', and in the state before starting. Stand still. Although not shown in the figure after turning on the switch 17,
The switch 17 'can be automatically turned on through the delay circuit. Further, as shown in Fig. 7, in order to prevent the melon M from being damaged, a flat body 15 "may be formed at the tip of the rod 15 so as to be elongated vertically and orthogonal to the rod 15. In this way, the melon is formed. 5 is preferable because the same position can be hit even if the size of the rod 1 is different.
The part of the coil 14 'which serves to pull back 5 is replaced by a spring 18
Is replaced with. That is, the magnetic rod 15 is
It is always pulled to the right by the spring 18 and the coil 14
Only when a current is applied to the coil 14 against the spring 18
Moves toward the center of the sword, further overshoots due to inertia, hits the melon 6, and is pulled back to the right by the spring 18 to return to the original rest state. It is also possible to use gravity instead of the spring 18 which plays a role of returning the magnetic rod 15 to the original state. That is, as shown in FIG. 6, the magnetic rod 15,
The coil 14 and the bobbin 13 are arranged diagonally, and the rod 15 is pulled up and hits the melon 6 only when a current is applied to the coil, and after tapping, it is pulled down diagonally by gravity and then returned to its original state. It may be configured to return to and stand still.

(Effects of the Invention) Since the present invention employs the above-described configuration, the strength of hitting a sample (melon) does not vary between skilled and unskilled people, adults and children, and the melon is used as a base. Ripeness (hardness) simply by placing it on the table and pressing one switch button
Can be measured. Further, since the vibration sound generated by hitting the sample is captured by the microphone installed in the substantially sealed case body, unnecessary external sound is hardly picked up. In addition, the fact that the distance between the microphone and the melon is always constant allows the accurate maturity to be known from accurate data. Further, even when the size of the sample of fruit and vegetables to be measured is large or small, the maturity can be corrected depending on the size of the sample, so that the accurate maturity can be known regardless of the size of the sample, and the device can be used. The whole is simple and can be manufactured compactly, so it is effective because the customer can measure the maturity with this device at the store and select the one with the maturity that suits his or her taste or taste. . On the farm, it is extremely effective in finding the optimal harvest time for fruit and vegetables, so
It is a low-cost product that can be widely used at various stages of the distribution system and contributes to stable quality.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the first invention, FIG. 2 is a vibration waveform diagram of a melon captured by a microphone, and FIG. 3 is a melon storage period and a melon without correction by the weight of the melon. FIG. 4 is a diagram showing the relationship between the natural frequency of melon and the natural frequency of the melon after being corrected by the weight of the melon.
5 and 6 are schematic diagrams of another embodiment of the electric tapping device, and FIG. 7 is a schematic configuration diagram of one embodiment of the second invention. 1 ... Sound collecting device, 2 ... Case main body, 3 ... Opening, 4 ... Microphone, 5 ... Mounting stand, 6 ... Passage, 7 ... Electric tapping device, 9 ... Frequency measurement circuit, 10 ... Display device, 11 ... Electronic only , 12 ... Frequency correction circuit, M ... Melon.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hironobu Tsuchida 2 31-50 Gotenyama, Takarazuka City, Hyogo Prefecture 503 (72) Gotenyama Mansion 503 (72) Inventor Minoru Tamura 5 1-5 Mihama, Urayasu City Chiba Prefecture 206 (56) References JP 62-44660 (JP, A) JP 1-217255 (JP, A) JP 2-310465 (JP, A) "-Commentary-Non-destructive analysis and measurement of food quality components", Agriculture, forestry and fisheries Published by Food Research Publication Society, Ministry of Food Research Institute, Sho 60-11-18, P39-44

Claims (2)

[Claims] 1. A measuring fruit vegetable made of an elastic material such as rubber or synthetic resin having a passage leading to the microphone on an upper opening of a case body having a microphone for capturing a vibration wave generated when the measuring fruit vegetable is hit. When a measurement table is installed on the table, the passage leading to the microphone provided on the table is closed and the case body is configured to be substantially sealed. A sound collection device, an electric tapping device that is controlled to hit the measurement fruits and vegetables with a predetermined strength, and a frequency measurement circuit that calculates the frequency from the cycle time of the vibration wave captured by the microphone. And a display device for displaying the displayed frequency, and a ripeness determination device for fruit and vegetables. 2. The sound collecting device according to claim 1 installed on an electronic scale for measuring the weight of fruits and vegetables, and an electric tapping device controlled to tap the fruits and vegetables with a predetermined strength. With a frequency measuring circuit that calculates the frequency from the cycle time of the vibration wave captured by the microphone, and the weight signal of the fruit and vegetables measured with the electronic only, the frequency obtained by the frequency measuring circuit, A fruit and vegetable ripeness determination device comprising a frequency correction circuit for correcting the frequency based on the difference in weight, and a display device for displaying the corrected frequency.