JPH0718843B2 - Ultrasonic inspection method for package contents - Google Patents

Description

TECHNICAL FIELD The present invention relates to an inspection method for determining the presence or absence and the degree of alteration of the contents of a package using ultrasonic waves.

Conventional technology Whether or not the contents such as food filled in a bag is deteriorated is checked for the presence or absence of expansion, because if the contents are deteriorated and gas is generated, the bag will expand due to the generated gas. It can be easily known by observing.

When the contents deteriorate and deteriorate without generating gas, if the bag is transparent, the presence or absence of the deterioration can be known by visually observing the contents through the bag. On the other hand, if the bag cannot be seen through, sample an appropriate number and break the bag,
A method of visually observing the contents is adopted.

Problems to be Solved by the Invention However, the method of visually observing the presence or absence of the expansion of the bag can be checked when the rot has progressed to a considerable extent, but the amount of gas is small in the early to middle stages of the rot. Was not suitable as a check means, and it was not possible to determine that deterioration rot did not occur because the bag did not expand.

Also in the method of visually observing the contents through a see-through bag, when the degree of alteration is not so advanced, it is often impossible to determine the presence or absence of alteration unless the bag is destroyed.

In addition, in recent food products, in order to improve shelf life, a laminated product in which aluminum foil is combined with the bag material is often used, but in this case, the bag breaking method as described above must be adopted. Didn't get

However, the inspection method of sampling a certain number of bags and breaking the bags has a great disadvantage that a lot of man-hours are required for the inspection, and even if the sampled products are non-defective, they will be lost due to the bag breaking. However, there is a problem in that there is much waste in terms of cost. In addition, in order to complete the inspection, it is necessary to increase the number of samplings as much as possible, but the number of samplings is naturally limited, and it is impossible to perform a 100% check, so the reliability was limited.

Also, even if the bag is made of a transparent material and the contents can be seen through, or even if the bag is made of a material that is not see-through, the contents can be visually inspected with a rupture bag,
In some cases, the alteration may not be clear by visual inspection, and it is impossible to eliminate the individual differences among the persons who inspect, and there is a problem that it is not always accurate to check the presence or absence of alteration.

It is an object of the present invention to provide a suitable method capable of accurately determining whether or not the contents of a package filled with a liquid food are altered and the degree of the alteration without destroying the package. .

Means for Solving the Problems In the method for inspecting the contents of a package by ultrasonic waves of the present invention, the package filled with a liquid food is shaken well in a state where it is kept horizontal and then made vertical, One of the outer surfaces is an ultrasonic probe, and the other outer surface is in contact with a metal reflection plate also serving as a support plate to keep the distance between the probe and the reflection plate constant,
In the contact state, ultrasonic waves having a wavelength range of 0.5 to 20 MHz are transmitted, and the presence or absence and the degree of alteration of the liquid food are determined based on the detected value when the reflected wave is received.

The present invention will be described in detail below.

As the packaging material constituting the packaging body, a single-layer or multi-layer plastic packaging material, metal, a laminate of metal foil and plastics, a metal deposition film, paper, a laminate of paper and plastics, cloth Those with resin coating,
Any leather or the like is used. Examples of the form of the packaging material include bags, tubes, containers and the like.

Liquid foods include liquid foods, paste foods and the like. It does not matter whether it is in a solid-liquid mixture state or a solid state, but since the dispersion at the time of measurement is large when the solids are unevenly distributed inside the packaging body, the present invention can be used when the solids are dispersed substantially uniformly inside the packaging body. Can be effectively applied.

The package filled with liquid food is first shaken well while keeping it horizontal and then made vertical. Without this preliminary operation, it is not possible to accurately determine the presence and degree of alteration of the liquid food product.

In the present invention, the ultrasonic probe is abutted on one outer surface of the package, and the metal reflector serving also as a support plate is abutted on the other outer surface of the package to keep the distance between the probe and the reflector constant. In this state, the ultrasonic wave is transmitted and the reflected wave is received.

The transmission and reception of reflected waves are usually performed using the same ultrasonic probe, but the ultrasonic probe on the transmitting side and the ultrasonic probe on the receiving side may be provided separately (however, both of the packaging On one outer surface).

By transmitting ultrasonic waves and receiving reflected waves, the detected values such as the difference in sound velocity between the transmitted wave and the received wave or the sound velocity of the received wave, the time from transmission to reception, and the degree of attenuation of ultrasonic energy can be obtained. In the present invention, the presence or absence and the degree of alteration of the contents are determined based on at least one of these detected values.

The wavelength range of the ultrasonic waves used is set to 0.5 to 20 MHz.

At the time of measurement, it is possible to make a determination using only a single frequency, but to select the frequency of the ultrasonic waves to be transmitted to determine the presence or absence and the degree of alteration of the liquid food that is the content. Then, the accuracy of the determination is further improved.

FIG. 1 is a block diagram showing an example of the inspection method of the present invention.

(1) is a package, in which the contents are filled and sealed inside the packaging material.

(2) is an ultrasonic probe which is in contact with one outer surface of the package (1).

(3) is a magnet scale, (4) is a length measuring converter, (5)
Is a transmission / reception circuit, (6) is a propagation attenuation detection circuit, (7) is a propagation time detection circuit, (8) is an arithmetic circuit, and (9) is a display circuit. (9) is a display circuit. The data is output from the white arrow (10).

Function: Holds the package at a fixed interval and transmits ultrasonic waves of a certain frequency from the ultrasonic probe that is in contact with one outer surface of the package, while reflecting on the other surface of the package or on the outside of that surface. It receives the reflected waves that hit the board and bounce back.

When the liquid food that is the contents is altered, the specific gravity changes and the viscosity changes, so the ultrasonic scattering, expansion, and absorption state of the ultrasonic waves differ between the unaltered contents and the altered contents,
As a result, the detected values such as the difference between the sound speeds of the transmitted wave and the received wave or the sound speed of the received wave, the time from transmission to reception, the degree of attenuation of ultrasonic energy, and the like are different.

The accuracy of the determination can be improved by selecting some frequencies of the ultrasonic waves to be transmitted in advance and finding out the optimum frequency suitable for the purpose of inspecting the package and the detection item to be measured.

EXAMPLES Next, the present invention will be further described with reference to Examples.

Example 1 A packaging made from a laminated film having a four-layer structure of a 12 μm thick polyester film / 9 μm thick aluminum foil / 15 μm thick biaxially stretched nylon film / 70 μm thick polyethylene film from the outermost layer to the innermost layer. The inside of the bag was filled with 200 g of liquid food (potage soup) so that the maximum thickness after filling was 30 mm.

Immediately after filling this package, the specific gravity is 1.06 and the viscosity is 50 cp.
The s and pH values were 6.7. (Hereinafter, referred to as non-deteriorated product) The filled package was left under the following conditions to produce altered products with various degrees.

Early deteriorated product: After filling, left at room temperature for 2 to 3 days Medium-term deteriorated product: After filling, left at room temperature for 5 to 8 days Late modified product: After filling, left at room temperature for 10 to 15 days When left at 40 ℃ for 2 weeks, the specific gravity is 1.06, the viscosity is 1500cps, and the pH value is 5.4.
The contents were yogurt-like. (Hereinafter referred to as "end-stage alteration products") The above five types of packages are kept horizontal, shaken well and then made vertical, and the ultrasonic probe is on one outer surface and the metal reflection plate also serves as a support plate on the other outer surface. Abutting against each other
The distance between the reflectors was kept at 25 mm.

Ultrasonic waves having frequencies of 1 MHz and 5 MHz were emitted from the ultrasonic probe and reflected waves were received, and the sound velocity, the time from transmission to reception, and the attenuation of ultrasonic energy were measured.

The results were as follows. The test was conducted on 10 packages each.

Test result Received sound velocity 1MHz Non-altered product 1670 ± 2m / sec Initial altered product 1674 ± 2m / sec Mid-term altered product 1677 ± 2m / sec Late altered product 1680 ± 2m / sec (transmitted sound velocity is 1683 ± 2m / sec) 5MHz Non-altered Product 1671 ± 2m / sec Initial alteration product 1672 ± 2m / sec Middle-term alteration product 1676 ± 2m / sec Late alteration product 1678 ± 2m / sec (Transmission sound velocity is 1683 ± 2m / sec) Time from transmission to reception 1MHz Non-alteration product 39.46 ± 0.02sec Early deteriorated product 39.50 ± 0.02sec Middle deteriorated product 39.57 ± 0.02sec Late deteriorated product 39.60 ± 0.02sec 5MHz Non-altered product 39.50 ± 0.02sec Initial deteriorated product 39.53 ± 0.02sec Middle deteriorated product 39.58 ± 0.02sec Late deteriorated product 39.64 ± 0.02sec Attenuation 1MHz Non-altered product −24.4 ± 0.3dB Initial altered product −20.3 ± 0.3dB Mid-term altered product −7.5 ± 0.3dB Late altered product −4.3 ± 0.3dB End altered product −3.5 ± 0.3dB 5MHz Non alteration Product −25.4 ± 0.3 dB Initially modified product −19.5 ± 0.3 dB Medium-term modified product −7.8 ± 0.3 dB Late modified product −4.0 ± 0.3 dB End modified product −2.0 ± 0.3 dB From the above results, Receiving It is particularly effective to measure the degree of attenuation of the reflected wave in the above example of potage soup, by knowing the time to the belief, or the degree of attenuation of ultrasonic energy, the degree of alteration of the liquid food that is the content can be determined. I understand.

Although a specific example is omitted, when the composition of the packaging material is variously changed, and when the same experiment as above is performed by variously changing the type of the liquid food that is the content, the presence or absence of alteration of the content,
The degree can be determined.

Effects of the Invention According to the method of the present invention, the following excellent effects are exhibited.

The determination can be made regardless of whether or not gas is generated when the liquid food that is the content is deteriorated and spoiled.

Since the package is not destroyed, it is possible to accurately determine whether the contents of the liquid food are altered or not, and to prevent loss due to inspection.

 Not only the presence or absence of alteration but also the degree of alteration can be determined.

The accuracy of determination is good regardless of the composition of the packaging material used and the type of liquid food that is the content.

Since it is more accurate than visual inspection depending on the type of liquid food that is the content, it is possible to check alterations that may be missed by visual inspection.

 A quick judgment is possible.

Not only can you check the sampled packages, but you can also check the total number online, so the inspection is highly reliable.

 There is no individual difference among the inspectors.

The cost burden of installing the equipment is small, and the man-hours of the inspector can be significantly reduced as compared with the visual inspection, which is also advantageous in terms of labor cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an example of the inspection method of the present invention. (1) ... Package, (2) ... Ultrasonic probe, (3) ...
… Magnescale, (4) …… Length measuring converter, (5) ……
Transmitter / receiver circuit, (6) …… Propagation attenuation detection circuit, (7) ……
Propagation time detection circuit, (8) ... Arithmetic circuit, (9) ... Display circuit, (10) ... White arrow

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Matsumoto et al. 1-4-16 Nihonbashi-Bakurocho, Chuo-ku, Tokyo Fujimori Kogyo Co., Ltd. (56) Reference JP-A-63-98584 (JP, A) 57-88069 (JP, U)

Claims (3)

[Claims] 1. A package filled with liquid food is shaken well in a horizontal state and then vertically made, and an ultrasonic probe is provided on one outer surface of the package and a support is provided on the other outer surface. When a metal reflector that also serves as a plate is contacted with each other to maintain a constant distance between the probe and the reflector, and when that contact is made, an ultrasonic wave in the wavelength range of 0.5 to 20 MHz is transmitted and a reflected wave is received. A method for inspecting the contents of a package by ultrasonic waves, which comprises determining the presence or absence and the degree of alteration of a liquid food based on a detected value. 2. The method according to claim 1, wherein the detected value is at least one of the difference between the sound speeds of the transmitted wave and the received wave, the sound speed of the received wave, the time from transmission to reception, or the degree of attenuation of ultrasonic energy. Inspection method described in paragraph. 3. The inspection method according to claim 1, wherein the package is a bag.