JPS62123340A - Fruit/vegetable ripeness sensor - Google Patents

Abstract

PURPOSE:To inspect the ripeness of fruit and vegetable in a dry and non- destructive manner without using water, by providing a microwave transmitter and its receiver to put an elastic body with the dielectric constant almost the same as an object to be measured tight on fruit and vegetable. CONSTITUTION:An object to be measured (fruit and vegetable) 1 is pinched without clearance with elastic bodies 7 and 8 having the dielectric constant almost the same as the object being measured. In the elastic bodies 7 and 8, microwave transmitter 2 and microwave receiver 3 are built at relative positions centered on the object being measured. The elastic bodies 7 and 8 herein used is rubber with addition of carbon powder or the like or those worked like a sponge and can be opened or closed mechanically in the direction of the arrow. To match changes in the outer diameter (b) of the object being measured, the outer diameter (d) is measured beforehand and on this data, a sensor interval L is controlled and further the measured values are softwarily corrected. According to this system, the scattering and diffraction of microwaves can be controlled, thereby enabling accurate measurement of attenuation of the object being measured. So, equal effect can be expected when water is used as measuring medium.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fruit vegetable ripeness sensor, and in particular to a fruit vegetable ripeness sensor that can perform the sugar content test of fruit vegetables in a highly accurate and non-destructive manner without adversely affecting the fruit vegetables. Regarding the degree sensor.

[Conventional technology]

In recent years, the production of vegetables and fruits has increased significantly due to improvements in dietary habits, and as a result, the size of fruit and vegetable sorting equipment in production areas has increased. In response to this increase in size, automation is currently being promoted to save labor and stabilize quality. Especially due to the Japanese people's preference for high quality fruits (melons, peaches, etc.)
Higher quality is required, and there is also a need to include not only appearance but also taste in sorting.

For example, when it comes to fruit, inspection items at fruit sorting plants include weight, size, shape, color, gloss, blemishes, and diseases.

Among these, sorting based on weight and size is called class sorting, and is easy to mechanize at fruit sorting plants.

Examples of these include Japanese Patent Publication No. 56-28683゜Sho 55-1828'5. 1972-87002. 1973-81348゜136864. 1974-11740. etc., and is also used at fruit sorting plants both in Japan and abroad.

Also, sorting based on shape, color, internal quality, etc. is called grading, and mechanization in fruit sorting plants has not yet reached a level of practical use, so it is mostly done by visual inspection. The number of people involved in this process reached 20 to 30 people at a large mandarin fruit sorting plant.
Since 20,000 to 30,000 mandarin oranges are processed per person per day, variations in judgment are likely to occur. By the way, there are 447 nationwide.
There are 7 fruit sorting stations, of which 2,372 are mechanical;
There are 2,105 manual jobs (1972 statistics).

As an example of mechanization of this grade sorting, there is
2-72289. 1975-117552. Dosho 5
4-144662, NET r C company catalog 0,
As seen in Fujiji 98 (Volume 52, No. 8, P31) < Because it relies on optical methods such as image processing by ITV and light reflectance, all estimates are from the outer skin and the inside of the fruit itself. It was not possible to measure the quality of This is clear from the results of a needs survey of agricultural cooperatives and distribution organizations that handle fruit, and there is a strong desire for a means to non-destructively measure the ripeness (sugar content) of fruit. It is even said that the distribution system will change.

In response to this need, Tsuruoka (Hitachi, Ltd., Central Research Laboratory) has developed a system in which the impedance (resistance), or attenuation of microwaves, when they pass through a measured object is correlated with sugar content (strictly speaking, sucrose). I confirmed that there is. This is Showa 56
Proceedings of the Metrology Society of Japan, November 2008, pp. 843-849, 1972.
Published in November 2015 as a material by the Institute of Electrical Engineers of Japan, document number rM-81-30. A conceptual diagram of the ripeness sensor of this invention is shown in FIG.

A fruit 1 whose total ripeness (sugar content) is to be measured is placed in water.Microwaves generated by a microwave generator 4 travel through the water from a transmitter 2, pass through the fruit 1, and are received by a receiver 3. . The amount of attenuation when the microwave passes through the fruit 1 is inputted to the analyzer 6 as the difference in radio wave strength between the microwave generator 4 and the receiver 5, and the sugar content inside the fruit is calculated.

FIG. 5 shows the relationship between the amount of microwave attenuation of prince melon and the sugar content measured by destructive inspection, and it can be seen from this figure that there is almost a correlation between the two. In FIG. 5, the solid line is approximately proportional to the amount of attenuation when a sucrose solution is placed in a spherical container.

The actual measured values for melons vary within the range shown by the dotted line, and this is the measurement accuracy.

The reason why water is used as the measurement medium here is that (1) water and the object to be measured are similar in nature, creating a condition in which radio waves propagate in a homogeneous space (2) microorganisms of water The two points are that the attenuation ability for waves is greater than that of the object to be measured, so it prevents diffraction of radio waves other than those traveling straight.

Figure 6 shows the microwave reception intensity when water is used as the medium and when no water is used.

Water is poured into a sphere made of quartz glass, which corresponds to a fruit.
When microwaves are transmitted from a transmitting antenna, comparing the strength of the received radio waves on the opposite side of the sphere when the medium is air and water, it is approximately OdB in the case of air, and the radio waves diffract on the outside rather than passing through the object to be measured. Then come. In the case of water, the attenuation is about 5 dB, which can be seen as attenuation due to passing through the object to be measured.

In other words, it can be seen that when measuring ripeness using this method, by using water as a measurement medium, sugar content can be measured from the amount of attenuation of microwaves transmitted only through the object to be measured.

[Problem that the invention seeks to solve]

However, according to the results of market research, it is impossible to use water in the fruit sorting and distribution process for the following reasons.

In other words, Japan has high humidity, so if there is any moisture left on the skin, mold will develop and the fruit will become unsaleable.

Also, if a drying process is added to remove this moisture, the freshness will drop, the value will drop, and it will not last long. For these two reasons, the use of water in this method was completely unthinkable, and an alternative method to water was needed.

The present invention provides a dry-type ripeness sensor that does not cause microwave diffraction and forms a homogeneous space with the object to be measured in the ripeness measurement of fruits and vegetables using microwaves. be.

[Means for solving problems]

When considering the role of water in the currently considered measurement methods, (1) it is homogeneous with fruits and vegetables (the dielectric constant is almost the same) (2)
) It has a certain degree of radio wave attenuation ability, and (3) It is in close contact with the object to be measured (without creating a space). In order to fulfill these roles and be dry, the fruit ripeness sensor should be made of an elastic body made of a material with a dielectric constant that is approximately the same as that of the object to be measured, or the receiver and transmitter should be made of an elastic body that has a high radio wave attenuation ability. It was found that by wrapping the sample in the body, the same effect as using water as the measurement medium can be expected.

[Effect]

Therefore, in the fruit and vegetable ripeness sensor of the present invention, the space between the microwave transmitter and the receiver is almost homogeneous with the measured object, suppressing microwave scattering and diffraction, or having a high microwave attenuation ability. Since the radio waves that bypass the object are absorbed, only the attenuation of the radio waves by the object to be measured can be accurately captured.

〔Example〕

Examples of the present invention will be shown below.

FIG. 1 shows a ripeness sensor having an elastic body homogeneous with the object to be measured.

An object to be measured (fruit, vegetable) l is sandwiched between elastic bodies 7 and 8 whose dielectric constant is almost the same as that of the object to be measured, with no gap between them. A microwave transmitter 2 and a microwave receiver 3 are built into the elastic body 7.8 at positions facing each other with the object to be measured at the center.

The elastic body 7.8 can be mechanically opened and closed in the direction of the arrow to sandwich the object to be measured.

The elastic body may have a dielectric constant close to that of the object to be measured 1 (for example, about ε-80 for melon, etc.).

Therefore, the elastic material used is one in which carbon powder, barium titanate powder, or the like is added to rubber, or one processed into a sponge shape. The shape of the elastic body is such that a recess corresponding to the type and size of the fruit is provided in the part where the fruit comes into contact with the fruit (or the like), and the elastic body is formed in advance into a shape that makes it easy to adhere to the fruit.

In this method, for changes in the outer diameter d of the object to be measured,
The outer diameter d is measured in advance, the sensor spacing is controlled using this data, and the measured value is further corrected using software.

According to this method, the space between the microwave transmitter and the receiver is almost homogeneous with the object to be measured, suppressing scattering and diffraction of microwaves, and thereby making it possible to accurately measure the attenuation of radio waves by the object to be measured.

FIG. 2 shows a ripeness sensor having an elastic body with a large ability to attenuate microwaves.

The object to be measured 1 is sandwiched between elastic bodies 9 and 10 made of a material with high microwave attenuation ability. Inside this elastic body is a microwave transmitter 2. A receiver 3 is provided at a position opposite to the object to be measured and in contact with the object to be measured.

Examples of the above-mentioned elastic body include one in which ferrite powder is added to rubber, or one in which ferrite powder is added to a sponge. In this case, since ferrite has a high radio wave absorption ability, changes in the outer diameter of fruits and vegetables in this method can be dealt with in the same manner as in the first method.

According to this method, the microwave emitted from the micro oscillator is almost absorbed by the elastic body, and only the radio waves that have passed through the object to be measured reach the receiver.

In other words, radio waves that bypass the object under test are absorbed between the transmitter and the receiver, allowing accurate attenuation of the object to be measured.

FIG. 3 shows an elastic sensor composed of an elastic membrane and fluid or powder.

In this figure, the object to be measured 1 is sandwiched between elastic membranes 11, 12 without gaps. At this time, the elastic membrane 11.1
2 is glued to the framework 13, 14, and has a fluid supply port 15.
The elastic membranes 11 and 12 are filled with the fluid supplied from the elastic membranes 11 and 12, and the gap with the object to be measured is reduced to zero.

In this state, a microwave transmitter 2 placed opposite the object to be measured 1 sends a radio wave to a microwave receiver 3 to measure attenuation.

This figure shows a case where a fluid with a dielectric constant similar to that of the object to be measured, such as water, is introduced, that is, a homogeneous space is created. It is also possible to provide the effect of the method shown in FIG. 5 by using a fluid with a large damping capacity, such as a jelly-like fluid to which ferrite powder is added.

[Effects of the Invention] According to the present invention, the ripeness of fruits and vegetables can be inspected in a dry and non-destructive manner without using water, which contributes to quality stabilization at fruit and vegetable production sites and distribution systems. Also, since no water is used, it is effective in maintaining fruit quality and automating measurement.

In addition, the present method eliminates the need for destructive inspection, which was conventionally performed by sampling.

[Brief explanation of drawings]

Figures 1, 2, and 3 are schematic diagrams of a ripeness sensor using an elastic body according to the present invention, Figures 4 are schematic diagrams of a conventional ripeness sensor using water, and Figure 5 is a schematic diagram of a ripeness sensor using a microwave. FIG. 6, an example of measurement using the ripeness sensor used, shows changes in radio field intensity due to differences in measurement media. 1... Object to be measured, 2... Microwave transmitter, 3...
・Microwave receiver, 4...Microwave generator, 5
...Microwave receiving device, 6...Analysis device, 7...
・Elastic body, 8...Elastic body, 9...Elastic body, 10...
・Elastic body, 11... Elastic membrane, 12... Elastic membrane, 13
... Framework, 14... Framework, 15... Block method supply port,
P...Fluid. Agent Patent Attorney Yusuke Hiraki Figure 1 Figure 2 Figure 5 Figure 7' Figure 6

Claims (1)

[Scope of Claims] 1. Place fruit vegetables whose sugar content is to be measured between a microwave transmitter and a receiver, and test the sugar content in the fruit vegetables based on the amount of attenuation or phase shift when the microwave passes through the fruit vegetables. In the fruit and vegetable ripeness sensor, the measurement medium has a built-in microwave transmitter and receiver, and has a dielectric constant almost equal to that of fruits and vegetables.
A fruit ripeness sensor composed of a deformable elastic body that can come into close contact with fruit vegetables. 2. In a fruit vegetable ripeness sensor that places the fruit vegetable whose sugar content is to be measured between a microwave transmitter and a receiver, and tests the sugar content in the fruit vegetable by the amount of attenuation or phase shift when the microwave passes through the fruit vegetable. A fruit vegetable ripeness sensor, in which a microwave transmitter and a receiver are placed in contact with an object to be measured, and the surrounding area is made of an electromagnetic wave absorbing material and is made of a deformable elastic body that can be brought into close contact with the fruit vegetables. 3. The fruit ripeness sensor according to claim 1 or 2, wherein the elastic body is integrally formed of a rubber-like or sponge-like material. 4. Claim 1, characterized in that the elastic body is composed of an elastic membrane forming an outer shell, and a powder or fluid filled therein and having a dielectric constant substantially equivalent to that of fruits and vegetables. fruit and vegetable ripeness sensor. 5. The fruit ripeness sensor according to claim 2, wherein the elastic body is composed of an elastic membrane having an outer shell and a powder or fluid made of an electromagnetic wave absorbing material filled therein. . 6. The fruit ripeness sensor according to claim 4 or 5, wherein the degree of adhesion to the object to be measured can be adjusted by adjusting the flow rate of the powder or fluid.