JPH10318991A - Fruits and vegetables judging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge a large quantity of fruits efficiently without requiring the skill of an expert by determining the eigen frequency of fruits using the impact sound propagation frequencies at the outer skin part and the edible part of the fruits thereby judging the ripeness thereof. SOLUTION: An impact sound generated by means of a hammer 12 and fruits 11 propagates through the outer skin part and the inner edible part of the fruits. An impact sound signal collected by sound collection mikes 13, 14 is amplified by an amplifier 15 and converted through an A/D converter 16 into a digital signal being delivered to a frequency analyzer 17. The frequency analyzer 17 extracts both a gradually damping frequency of an initial impact vibration propagating through the outer skin and the vicinity thereof, and a gradually clamping frequency of an impact vibration propagating through the inner edible part. The eigen frequency of the fruits is the calculated by extracting the frequency of impact vibration propagating through the edible part having a lower peak value than the frequency of impact vibration propagating through the outer skin part. Since the lowering of the eigen frequency represents an increase of the ripeness, the ripeness can be determined without relying upon an expert.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for judging fruits and vegetables, which gives an impact sound to fruits and vegetables, detects the propagation state of the impact sound in the fruits and vegetables, and judges the hardness of the fruits and vegetables.

In particular, it is useful for judging the degree of ripening of fruits and the degree of pain.

[0003]

2. Description of the Related Art Conventionally, the determination of the maturity and the degree of pain of fruits and vegetables is carried out at the time of harvest and shipment or sale by judging the appearance shape and color of the target fruits and vegetables and extracting a sample of the fruits and vegetables.
The samples are destroyed, and the ripening state and the sugar content in the fruits and vegetables are measured. Judgment by the appearance,
Many years of experience are required, and the judgment of destruction by sampling is wasted because the destroyed fruits and vegetables cannot be sold as commodities. Especially for fruits, etc., there is a time lapse between the time of harvest shipment and market sale, and the ripening of the fruit is progressing during that time. When harvested and sold on the market, it must be provided as a fully aged product without spoilage.

As a method for accurately and uniformly judging the ripening of fruits and vegetables without relying on experienced persons, various judging devices have been developed and used. A typical example of this determination device is a watermelon maturity determination device.

[0005] The determination of the degree of ripening of watermelon is made by a skilled producer or salesperson striking the watermelon by hand, and based on the feel at that time, the quality of the hitting sound and the degree of sound. Utilizing the quality and the sound, the impact sound transmitted through the watermelt is collected using a microphone, and the frequency of the collected sound is analyzed to determine the maturity. The sound that propagates through the watermelon is divided into those that propagate through the hard skin portion of the surface of the watermelon and those that propagate through the interior of the watermelon. Need to be collected and frequency analyzed. However, the watermelon has a generally eating part (red part) inside the watermelon immediately after fruiting, and contains a lot of water. Therefore, the sound propagating inside the watermelon is attenuated by the water. On the other hand, the surface of the watermelon has an epidermis and a part of the inner part of the epidermis that does not normally eat (white part) with a certain thickness, and this epidermis and parts that do not generally eat (hereinafter referred to as the epidermis part) are transmitted. Because the sound is hard,
Good propagation rate. By this, after collecting the sound transmitted through the skin portion of the watermelon and inside, when analyzing the number of collected waves, the sound transmitted through the skin portion can be obtained in a sufficient amount necessary for analysis, but it is propagated inside. The volume of the sound is small and is superimposed on the sound propagated through the epidermis, making it difficult to analyze the epidermis and the internal propagation. In addition, as the ripening of the watermelon progresses, the epidermis maintains the fruit quality at the time of harvesting for a long time, but the inside is cracked and the water content decreases. Therefore, the maturity is determined only by performing frequency analysis mainly using the sound propagating in the epidermis.

However, fruits that show a different growth state from watermelon, such as melon, are generally hard to eat from the time of fruiting until immediately after harvest, and cannot be eaten as they are. For this reason, the ripening of the inside proceeds by leaving it for a certain period after the harvest, and the progress of the ripening is determined to be shipped and marketed. Even if a melon following such a growth process is used with the same determination device as the above-mentioned watermelon, both the sound propagating inside the melon and the sound propagating through the epidermis are detected, and the maturity cannot be determined. There is no other way than to judge the inner ripening degree by destroying the experience or its melon, a large number of skilled workers are required for ripening judgment at the collection point where a large amount of fruits from different producers are collected,
There is a demand for more efficient maturity determination.

[0007]

As described above, the edible portion of the fruit is hard until immediately after harvesting, and the fruit is matured by providing a ripening period after harvesting. There is a problem that a large number of skilled persons are required to judge a large number of fruits different from one another, and a lot of time is required for a shipping judgment work.

[0008]

According to the present invention, there is provided a sound collecting means for collecting an impact sound propagating through a non-edible skin portion and an internal edible portion of the object to be determined, and a sound collected by the sound collecting means. The natural frequency generating means for generating the natural frequency of the object to be determined based on the impact sound transmitted through the skin portion and the edible portion of the fruits and vegetables, by the natural frequency of the object to be determined,
A fruit / vegetable judging device for judging hardness or maturity of the object to be judged.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the edible portion inside a fruit is hard to be edible from fruiting to harvesting like fruits such as melon from fruits and vegetables. By providing a certain ripening period, the edible portion inside the fruit is ripened and provided for edible use. The ripening of the edible portion expands from the central portion of the fruit to the outer skin side, and as the ripening progresses, ripens to just inside the outer skin. Further, as the ripening proceeds to putrefaction, the outer skin surface also becomes soft. Using the progress of ripening of the fruit, the present inventor repeated a number of experiments, and focused on the fact that the natural vibration frequency of the fruit changes differently with the progress of ripening inside the fruit. .

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of a fruit and vegetable determination device according to the present invention.

In FIG. 1, reference numeral 11 denotes an object to be determined, such as a melon. The determination target 11 is placed on a determination target fixture (not shown). A hammer 12 is provided near the fixture to be determined and generates an impact sound by hitting the object 11 to be determined. This hammer 12
Has a fixed central portion, one end is a hitting portion for hitting the object to be determined 11, and the other end is constituted by a hammer driving portion for lifting the hitting portion by a predetermined angle, and presses the hammer driving portion downward in the figure. After the hit point is lifted by a predetermined angle, the hit point is dropped in the direction of the arrow shown by the dotted line in the figure, and the object 11 is hit with a predetermined force. The impact sound generated by the hammer 12 and the object 11 is transmitted to the outer skin portion and the edible portion of the object 11. Two sound collectors 13 and 14 composed of a microphone or the like that collects the impact sound are attached so as to be in close contact with the object 11 to be determined. The analog impulsive sound signal propagated through the object to be determined 11 collected by the sound collectors 13 and 14 is supplied to an amplifier 15 and is amplified into an impulsive sound signal having a predetermined magnitude. The impact sound signal amplified by the amplifier 15 is converted from an analog signal to a digital signal by an AD converter. When converted to this digital signal,
Only the vibration frequency of the impact sound generated by the judging object 11 and the hammer 12 collected by the sound collectors 13 and 14 is converted into a digital signal, and the other sounds collected through the determined portion 11 To eliminate the vibration frequency.
The vibration frequency of the impact sound converted into a digital signal by the AD converter 16 is supplied to a frequency analyzer 17 composed of an electronic computer or the like. In this frequency analyzer 17, the object 11 to be determined collected by the sound collectors 13 and 14 is
The first shock vibration transmitted through the outer skin and the outer skin portion in the vicinity thereof and the vibration frequency that attenuates gradually (hereinafter referred to as the outer skin portion transmission vibration frequency), and the shock transmitted through the inner edible portion of the determination target 11 Both the propagation vibration frequency of the vibration and the vibration frequency that attenuates gradually (hereinafter referred to as the edible partial propagation vibration frequency) are extracted. The peak values of both the propagation vibration frequencies of the outer skin portion and the edible portion are determined.

At the time of harvest, the melon, which is the object 11 to be determined,
Both the hull and the edible part are hard, and the propagation vibration frequency of both parts shows almost the same vibration frequency, but as the ripening of the edible part progresses, the hull part does not change, but the hardness of the edible part decreases, A change occurs in the vibration frequency. That is, the propagation vibration frequency decreases as the edible portion ages.

The edible portion propagation vibration frequency can be determined from the difference in the propagation vibration frequency between the outer skin portion and the edible portion, and the edible portion propagation vibration frequency having a peak value lower than the outer skin portion propagation vibration frequency is extracted. Thus, the natural vibration frequency of the determination object 11 is calculated.

Therefore, the natural vibration frequency decreases as the maturity and range of the edible portion of the determination target 11 increase. The decrease in the natural vibration frequency indicates that the hardness of the test object 11 is low and the ripening degree is increased, without relying on a skilled person to judge the ripening degree of the fruit.
It has become possible to provide a fruit and vegetable judging device that can be distinguished.

As a result of an experiment conducted by the present inventor using a plurality of melon samples using the above-described apparatus, as shown in the graph of FIG. 2, the natural frequency changes depending on the hardness of the melon. It was found that this hardness was proportional to the maturity of the edible part of the melon. The distribution of the natural frequency is stored in the frequency analyzer 17, and each time the natural frequency of each melon is measured, it is compared with the distribution to determine the hardness of each melon, that is, the maturity. Could be possible.

Since the natural frequency of the melon differs depending on the size of the melon, a weight measuring device for the object 11 is provided on the fixture for mounting the object 11 on which the object 11 is mounted. By correcting the natural frequency of the object 11 with the measured weight value by the frequency analyzer 17, it is possible to equalize the natural frequency due to the size of the object 11 and eliminate an error in the hardness determination. .

In the above description, the peak value of the propagation vibration frequency of the outer skin portion and the edible portion of the object to be determined 11 collected by the sound collectors 13 and 14 is used for the determination of the hardness or the maturity of the object to be determined 11. Although a low value was used, more accurate determination can be made possible by using the average value or difference value of the peak values of the propagation vibration frequencies of the outer skin portion and the edible portion. It is clear that the present invention can be realized by averaging the frequencies of the first impact vibration and the damping vibration of the edible portion and comparing the average value with the average value as described above.

Still further, a plurality of objects to be determined of the object to be determined 11 of the present invention are provided on a plurality of conveyors, and the conveyor is circulated to thereby automatically determine a large number of objects to be determined. Is output from the frequency analyzer, and the quality of the shipment for each of the objects to be determined is transmitted, and it is apparent that the automatic sorting can be performed.

[0019]

As described above, according to the present invention, a predetermined impact sound is given to a fruit without discrimination of the degree of ripening of the fruit by a skilled person, and the impact noise of the outer skin portion and the edible portion of the fruit is reduced. The natural frequency of the fruit is obtained using the propagation vibration frequency, and the hardness or the ripening degree of the fruit is determined based on the natural frequency, so that a large amount and efficient sorting or discrimination can be easily realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a fruit and vegetable determination device according to the present invention.

FIG. 2 is a graph showing the relationship between the hardness of a vegetable and the natural frequency measured by the vegetable determination apparatus according to the present invention.

[Explanation of symbols]

11: object to be determined, 12: hammer, 13, 14: sound collecting microphone, 15: amplifier, 16: AD converter, 17 ...
Frequency analyzer.

Claims (6)

[Claims] 1. An impact providing means for applying an impact sound to an object to be determined, a sound collecting means for collecting an impact sound propagating through a skin portion and an edible portion of the object to be determined, and a sound collected by the sound collecting means. Natural frequency generation means for generating a natural vibration frequency of the object to be determined based on the impact sound propagated through the skin portion and the edible portion of the object to be determined, and by the natural vibration frequency of the object to be determined, An apparatus for determining fruits and vegetables, which determines the hardness of the object to be determined. 2. The method according to claim 1, wherein the natural frequency generation means uses a low value of a peak value of the vibration frequency among the vibration frequencies transmitted through the skin portion and the edible portion of the determination target to determine the characteristic of the determination target. The fruit and vegetable determination device according to claim 1, wherein the vibration frequency is calculated. 3. The natural frequency generating means averages vibration frequencies transmitted through a skin portion and an edible portion of the object to be determined, and uses a low value of the average value to calculate a natural vibration of the object to be determined. The fruit and vegetable determination device according to claim 1, wherein the frequency is calculated. 4. The natural frequency generating means calculates a difference value between vibration frequencies transmitted through a skin portion and an edible portion of the object to be determined, and uses the obtained difference value to calculate a natural vibration of the object to be determined. The fruit and vegetable determination device according to claim 1, wherein the frequency is calculated. 5. The natural frequency generating means for correcting a natural frequency of the object to be determined by adding a correction based on a weight value of the object to be determined to a vibration frequency transmitted through a skin portion and an edible portion of the object to be determined. The fruit and vegetable determination device according to claim 1, wherein the fruit and vegetable determination device calculates 6. The object to be determined is a fruit, and the ripening degree of the fruit is determined based on a natural frequency generated by the natural frequency generating means.
A fruit and vegetable determination device according to any one of the above.