JPH039252A - Inspecting device for foreign matter in sliced raw shellfish - Google Patents

Abstract

PURPOSE:To detect foreign matter without being affected by the output variation of an X-ray source and the component variation of fluid for conveyance and to preclude an omission of detection by using both a multiplexer system and a multichannel system together. CONSTITUTION:A body to be inspected is irradiated with X rays emitted by an X-ray generation tube and transmitted X rays are measured by linear sensors 26A and 26B. Signals of respective photodetecting elements of the sensor 26A are applied to a multiplexer 32, which outputs a signal indicating the transmission quantity of X rays in the array direction of the sensor 26A to a signal processing circuit 34. The circuit 34 compares signals of individual channels relatively and outputs a foreign matter detection signal when a signal difference exceeds a specific level. Signals of photodetecting elements of the sensor 26B, on the other hand, are apllied to comparators comp.1 - comp.m, which compares the signal levels of respective channels with a threshold value and output an abnormality detection signal through an OR circuit 38 when the signal level of a channel becomes smaller than the threshold value.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an apparatus for inspecting foreign substances in shellfish shellfish, and in particular detects shell fragments and foreign matter mixed in shellfish shellfish based on the amount of X-ray transmission. This invention relates to a foreign object inspection device in shellfish shellfish that detects foreign objects such as metal pieces.

[Conventional technology]

Conventionally, there is a method of irradiating processed foods with X-rays and detecting foreign substances mixed in the processed foods based on changes in the amount of transmitted X-rays from the processed foods (Japanese Patent Laid-Open No. 127393/1983).

However, in the case of the above-mentioned X-ray inspection method, although it has a great track record in detecting foreign substances in foods other than shellfish, when applied to detecting the remains of shellfish such as clams, the X-ray absorption Because the difference is not so large, the detection of residual grains in shellfish shells is
Devices that use wires have not been put into practical use until now.

On the other hand, in recent years, X-rays are irradiated onto the shellfish and its transport fluid passing through the pipeline, and the upper surface of the X-ray receiving element that receives the X-rays through the pipeline is exposed to the X-rays. A device for inspecting the remaining grains in shelled shellfish has been proposed by installing a luminescent X-ray fluorescent screen (Japanese Patent Application No. 62-26309).
No. 0).

Also, Food Machinery and Equipment (1987, December issue, p. 84~
90 pages), an online one-dimensional X-ray sensor is used in an X-ray inspection system for foreign substances mixed in food, and this one-dimensional X-ray sensor has 35 photodiode elements of IX4. Each photodiode element has I x 1 x 4 as a phosphor.
．． There is a description that 4 mrn X-ray emitting crystals are optically coupled.

Furthermore, the signal processing method in this type of device involves sequentially inputting the signal levels of multiple X-ray photodetectors at a predetermined cycle time, and comparing the relative magnitudes of each signal level to detect foreign particles. The so-called multiplexer method determines the presence or absence of a foreign object, and the so-called multiplexer method determines the presence or absence of a foreign object by inputting the signal levels of multiple X-ray photodetectors over time and comparing the signal level with a threshold for foreign object detection. There are multi-channel systems, and conventionally one of these systems has been adopted.

[Problem to be solved by the invention]

By the way, when a small amount of change in X-rays is a problem, as in the case of the conventional grain residue inspection device for peeling shellfish, if a multi-channel method is used as the signal processing method, for example,
There is a problem in that the amount of X-ray transmission varies due to variations in the output of the X-ray source, variations in the components of the transport fluid, etc., and therefore it is difficult to set a threshold value that is a discrimination criterion for seashell detection. Note that if the darkness value is fixed, detection becomes unstable, and on the other hand, it is troublesome to change the threshold value each time. On the other hand, when a multiplexer method is used, signals are input from each X-ray photodetector at every predetermined cycle time, which makes detection difficult if the shell is small or the shell is moving fast.

In other words, since the multi-channel method is a real-time measurement, it has excellent responsiveness but is weak against X-ray fluctuations, while the multiplexer method is strong against X-ray fluctuations but lacks responsiveness. have.

In addition, depending on the material to be detected by the X-ray inspection device (e.g., stone, metal, wood, plants, etc.) and its dimensions, the optimal X-ray energy for detection or the phosphor and X-ray suitable for the X-ray energy may be used. It is a well-known fact that there are dimensions of the light-receiving element, etc., but in the case of conventional shell fragment inspection equipment, it is possible to detect shell fragments larger than a predetermined size, but for example, small Metal fragments cannot be detected. In addition, even in the X-ray inspection equipment described in the food machinery equipment literature, it is necessary to use a one-dimensional X-ray sensor etc. that is set only under certain specific conditions. Naturally, it cannot be detected.

The object of the present invention has been made in view of the above circumstances, and it is an object of the present invention to develop a method for detecting even the smallest foreign matter stably even in the face of fluctuations in the output of X-rays or fluctuations in the composition of the transport fluid. An object of the present invention is to provide a foreign matter inspection device.

Another object of the present invention is to provide a foreign object detection device in shell body that can efficiently detect foreign objects made of various materials and sizes, such as shell pieces and metal pieces, using one X-ray source. It is about providing.

[Means to solve problems]

In order to achieve the above object, the present invention provides a conveying means for continuously conveying shellfish shells together with a transporting fluid through a pipeline, and X-rays for shellfish shells and the transporting fluid passing through the pipeline. X-ray irradiation means for irradiating the X-ray irradiation means, and a plurality of minute X-ray light receiving elements are arranged in a straight line in a direction crossing the pipeline, and receive the X-rays from the X-ray irradiation means via the pipeline. The signal levels of the first and second one-dimensional X-ray sensors and the individual X-ray receiving elements of the first one-dimensional The first discriminating means discriminates whether there is a foreign object in the shellfish shell by comparing the sizes thereof, and the signal level of each X-ray receiving element of the second one-dimensional X-ray sensor is determined over time. and second determining means for determining the presence or absence of foreign matter in the shellfish shellfish by inputting the signal level to a predetermined threshold value for detecting foreign matter and comparing the signal level with a predetermined threshold value for detecting foreign matter.

Further, a transport means for continuously transporting the shellfish shells together with a transport fluid through a pipeline, and an X-ray irradiation means for irradiating X-rays to the shellfish shells and the transport fluid passing through the pipeline; An absorber that is disposed between the X-ray irradiation means and the pipeline and absorbs long wavelength components of some of the X-rays in the X-ray irradiation optical path, and a plurality of small X-ray light receiving elements are connected to the pipeline. A fluorescent substance sensitive to long-wavelength X-rays is disposed on the upper surface of the fluorescent substance, which is arranged in a straight line in a direction transverse to the absorber and at a position to receive X-rays that do not pass through the absorber. A first one-dimensional XvA sensor that receives X-rays through a pipeline, and a plurality of minute X-ray receiving elements that receive X-rays that pass through the absorbing material in a straight line in a direction that crosses the pipeline. The second
A one-dimensional X-ray sensor, in which a fluorescent material sensitive to short wavelength X-rays is disposed on the upper surface thereof, and a second X-ray sensor that receives X-rays from the X-ray irradiation means via an absorbing material and a pipeline.
a one-dimensional X-ray sensor, and said first and second one, respectively.
The present invention is characterized by comprising a determining means for determining the presence or absence of foreign matter in the shellfish shellfish based on the signal level of the dimensional sensor.

[Effect]

The present invention addresses the problem of X-ray generation source output fluctuations (in the short term, power supply voltage fluctuations,
In the long term, the amount of transmitted X-rays may fluctuate due to changes in the X-ray generating tube (e.g. aging of the X-ray generating tube) or changes in the composition of the object, so each X-ray receiving element (channel) is
It is designed to perform relative comparisons between the two, and at the same time provide responsiveness through real-time measurement using a multi-channel method. In other words, two one-dimensional X-ray sensors are installed as sensors that receive X-rays, and one one-dimensional sensor is used for signal processing using a multiplexer method, which allows detection of foreign objects that are resistant to fluctuations in X-rays. enable the other one
The dimensional sensor is used for multi-channel real-time signal processing, making it possible to detect foreign objects when the size of the foreign object is small or when the moving speed of the foreign object is high.

In addition, the present invention focuses on the fact that the effective X-ray energy for detection differs depending on the material of the foreign object, and that detecting accuracy can be improved by appropriately selecting the fluorescent material of the one-dimensional sensor accordingly. In order to separate the X-rays irradiated from one X-ray irradiation means into X-rays of multiple energy bands, an absorbing material that absorbs some of the long wavelength components of the X-rays is provided in the X-ray irradiation optical path. I have to. On the other hand, first and second one-dimensional sensors are arranged at positions that receive X-rays that do not pass through the absorbing material and at positions that receive X-rays that pass through the absorbing material, respectively. A fluorescent material sensitive to long wavelength X-rays is disposed on the upper surface, and a fluorescent material sensitive to short wavelength X-rays is disposed on the upper surface of the second one-dimensional sensor. Thereby, signal levels suitable for the material and size of the foreign object can be extracted from the first and second one-dimensional sensors, respectively, and various foreign objects can be detected simultaneously.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the apparatus for inspecting foreign substances in shellfish shellfish according to the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1, a specimen (a mixture of shellfish shells, shell pieces, foreign objects such as metal pieces, and a transport fluid) is supplied to a supply tank 12 through a supply port 10. In the supply tank 12, while stirring with a stirrer 14, the mixing ratio of the shellfish and the transporting fluid is adjusted and the specific gravity of the fluid is adjusted.

The subject after adjustment is supplied to the X-ray inspection section 20 by a rotary pump 17 through a pipeline 16 made of sanitary SUS. In FIG. 1, 18 is a device stand, and 19 is a drain valve.

In the X-ray inspection section 20, the X-rays irradiated from the X-ray generating tube 22
The X-rays are irradiated onto the subject through the vibration line 24 made of carbon FRP, and the transmitted X-rays are sent to the one-dimensional X-ray sensor 26.
A, measured at 26B.

When foreign objects such as shell pieces and metal pieces are detected in the subject based on the outputs of the one-dimensional X-ray sensors 26A and 26B, a foreign object detection signal is generated, and a discharge valve is opened based on this foreign object detection signal. 30 to discharge the object containing foreign matter.

Next, the X-ray inspection section 20 will be explained in detail with reference to FIGS. 2 to 6.

FIG. 2 is an enlarged sectional view of the X-ray inspection section 20.

In the same figure, the X-ray generating tube 22 is
A long wavelength X-ray absorbing material (aluminum thin film) 22B is disposed on a part of the surface of 2A (the right half in the figure). As a result, the X-ray irradiation area is divided into irradiation area #c (the irradiation area on the left side of the center line in the figure) which contains many long wavelength The irradiation area is separated into B and B. And vibe line 24
Each lower irradiation area A and B is provided with a one-dimensional X-ray sensor 26A suitable for detecting long wavelength X-rays and short wavelength X-rays, respectively
and 26B are provided.

Here, the effect of separating X-rays into short-wavelength and long-wavelength X-rays on foreign object detection will be explained.

Generally, it is well known that X-ray absorption by animals and plants is lower than that of metals, etc., and seashells, which are the main inspection target of the present invention, do not have a high X-ray absorption rate. line is required for detection.

On the other hand, metal pieces and stones that are present in the specimen have a high absorption rate not only for long-wavelength X-rays but also for short-wavelength dimensions are small.

Therefore, the signal due to the absorption of long wavelength X-rays by the carbon FRP vibrating line 24 or the transport fluid may obscure the signal due to the absorption of X-rays by metal or stone. Therefore, it is more effective to detect these using short wavelength X-rays that are less absorbed by the vibrator 24 or the transport fluid.

From the above, in the present invention, the wavelengths (energy) of X-rays used for detection are divided between seashells, metals, and stones.

Next, details of the one-dimensional X-ray sensor 26 selected based on the XWA wavelength and the size of the detection target will be described.

FIG. 3 is a perspective view showing the configuration of the one-dimensional X-ray sensor 26. The one-dimensional X-ray sensor 26 is composed of a photodiode array 27 in which a plurality of light receiving elements 27A are arranged in a row, and a fluorescent substance 28. ing.

Here, FIG. 4 shows the absorption characteristics of various fluorescent substances with respect to X-ray energy. As shown in the figure, gadolinium terbium oxysulfide (Gd20.5-Tb) and calcium tungstate (CaWO4) are effective for long wavelength (low energy) X-rays that are effective for detecting seashells.
On the other hand, X-rays with short wavelengths (high energy) that are effective for detecting metals and stones are
d202S-Tb), lanthanum terbium oxysulfide (L
a202S' Tb), cesium sodium iodide (Csl.Na) and lanthanum terbium acid bromide (
LaOB, 5-Tb) are effective.

That is, the one-dimensional X-ray sensor 26A shown in FIG. 2 has a fluorescent substance 28A sensitive to long-wavelength X-rays on its upper surface, and the one-dimensional X-ray sensor 26B has a fluorescent material 28A sensitive to short-wavelength X-rays on its upper surface. A sensitive fluorescent substance 28 is provided.

In addition, by appropriately selecting the element dimensions of the one-dimensional X-ray sensor according to the dimensions of the detection target mentioned above, a high dynamic range of the detection signal can be obtained. 0.5 to 1 stroke in total
．． On the other hand, for the detection of metal pieces and stones, the element size is 0.5 to 1.5 mm in terms of the frequency of appearance. O
The element dimension is ma+angle.

Next, a preferred shape of the carbon FRP pipeline 24 in the X-ray inspection section 20 will be described using FIG. 5.

FIG. 5(A) is a cross-sectional view of the pipeline 24 in a direction perpendicular to the transport direction of the subject. The pipeline 240 has a trapezoidal shape, with straight lines connecting both ends forming both sides of the pipeline 240. This eliminates the dead space DS seen in a rectangular pipeline (indicated by a broken line), which significantly improves detection accuracy.

FIG. 5(B) is a cross-sectional view of the pipeline 24 in a direction parallel to the transport direction of the subject, and as shown in the figure,
Pipeline 2 at the portion intersecting the plane connecting the one-dimensional X-ray sensors 26A, 2.68 and the target of the X-ray generating tube 22
4 has recesses 24A and 24B to reduce X-ray absorption by those parts. As a result, detection accuracy was improved while minimizing the mechanical strength of the pipeline 24.

In addition, in this embodiment, the balaine 2 in the X-ray inspection section 20
Carbon FRP is used as the material in step 4 because it has a higher X-ray transmittance than vinyl chloride or acrylic materials, and is superior in terms of mechanical strength and chemical resistance. This makes it possible to ensure sufficient durability against hot water cleaning and chemical cleaning for food hygiene reasons.

Next, a signal processing method for signals obtained from the one-dimensional X-ray sensor will be explained using FIGS. 6 and 7.

In the present invention, a multiplexer method and a multichannel method are used together as a signal processing method for detecting a foreign object based on a signal from a one-dimensional X-ray sensor.

First, the multiplexer method will be explained.

In FIG. 6, the signals of each light receiving element (n channels ch, l to ch, n) of the one-dimensional X-ray sensor 26A are applied to the multiplexer 32, which sequentially sends the signals of the n channels. , and outputs it to the signal processing circuit 34 . That is, the multiplexer 32 sets the time required to read out the signals of n channels as one cycle, and as shown in FIG. 7(A), the multiplexer 32 adjusts the
A signal indicating the amount of line penetration is output to the signal processing circuit 34. Note that when a shell piece passes over the one-dimensional X-ray sensor 26A, the signal of the light receiving element (channel) at the place where it passes decreases.

The signal processing circuit 34 compares the relative magnitudes of the signal levels of the individual channels, determines that a foreign object (shell piece) has been detected when the signal deviation is above a predetermined level, and outputs a foreign object detection signal.

In this way, the multiplexer method has the advantage of not being affected by fluctuations in the X-ray source because relative comparisons are made between the channels. However, if the shell fragments are extremely small, sufficient detection accuracy cannot be obtained.

Next, the multi-channel system will be explained.

In FIG. 6, the signals of each light receiving element (m channels ch, l~ch, m) of the one-dimensional XwA sensor 26B are transmitted through comparators comp, 1~comp, m, respectively.
l has been added, and each comparator comp, 1~ca
A predetermined threshold value for foreign object detection is added from a level setter 36 to the input of the pond mρ1m.

Each of the comparators comp, l to comp, m compares the signal level of each channel with the threshold value as shown in FIG. 7(B), and when the signal level of the channel becomes smaller than the threshold value, the foreign object detection signal is is outputted via the OR circuit 38.

In this way, the multi-channel method inputs signals from each light-receiving element (channel) of the one-dimensional X-ray sensor 26B over time, and detects foreign objects by comparing the signal level with a preset threshold. It has good responsiveness and is effective in detecting foreign objects such as small metal pieces and stones.

When a foreign object detection signal is output from at least one of the signal processing circuit 34 or the OR circuit 38, the discharge valve 30 (FIG. 1) is operated as described above to discharge the object containing the foreign object.

In this embodiment, the long-wavelength X-ray absorbing material is provided directly at the window of the X-ray generating tube, but the material is not limited to this, and may be placed in the space in the middle of the X-ray irradiation optical path or a part of the surface of the pipeline 240. A similar effect can be obtained by disposing an absorbent material in the area. Further, although a thin film of aluminum is used as a long-wavelength X-ray absorbing material, other materials may be used as long as they absorb only long-wavelength X-rays and transmit short-wavelength X-rays.

〔Effect of the invention〕

As explained above, according to the apparatus for inspecting foreign substances in shellfish shells according to the present invention, two signal processing methods, a multiplexer method and a multi-channel method, are used together, so output fluctuations of the X-ray source and the transport fluid It is possible to detect foreign objects without being affected by component fluctuations, and it is also possible to prevent missing detection even when the size of the foreign object is small or when the specimen is transported at a high speed.

In addition, one X-ray generation source is used to irradiate X-rays with two types of energy bands suitable for each material such as shell pieces and metal pieces, and two fluorescent substances effective for each X-ray energy are used. Since it is disposed in a one-dimensional X-ray sensor, a highly sharp signal waveform can be obtained, thereby improving the foreign object detection rate.

[Brief explanation of the drawing]

Figure tJEi is an overall configuration diagram showing an embodiment of the present invention, Figure 2 is an enlarged sectional view of the X-ray inspection section in Figure 1, and Figure 3 is an illustration of the one-dimensional X-ray sensor in the X-ray inspection unit in Figure 1. A perspective view showing the configuration, FIG. 4 is a graph showing the absorption characteristics of various fluorescent substances with respect to X-ray energy, and FIGS. 5 (A) and (B) are cross-sectional views of the pipeline in the X-ray inspection section of FIG. 1, respectively. 6 is a block diagram schematically showing the signal processing unit of the present invention, and FIGS. 7(A) and (B) are for explaining signal processing of a multiplexer method and a multichannel method, respectively. It is a signal waveform diagram used. 16.24...Pipeline, 17...Rotary pump, 20...X-ray inspection department, 22...X
Line generator, 22A... Beryllium window, 22B.
... Absorbing material, 26.26A, 26B. One-dimensional X-ray sensor, 27A... Light receiving element, 27... Photodiode array, 28.28A, 28B... Fluorescent material, 32... Multiplexer, 34 ...Signal processing circuit, 36-...Level setting device, comp, l
~comp, m --- Comparator.

Claims (3)

[Claims] (1) A transport means for continuously transporting the shellfish shells together with a transport fluid through a pipeline; and an X-ray irradiation means for irradiating X-rays to the shellfish shells and the transport fluid passing through the pipeline. , first and second one-dimensional structures each having a plurality of minute X-ray receiving elements linearly arranged in a direction crossing the pipeline and receiving X-rays from the X-ray irradiation means via the pipeline; By sequentially inputting the signal levels of the X-ray sensor and the individual X-ray light receiving elements of the first one-dimensional X-ray sensor at a predetermined cycle time, and comparing the relative magnitudes of each signal level. A first discriminating means for determining the presence or absence of a foreign object in the shellfish shellfish, and a signal level of each X-ray receiving element of the second one-dimensional X-ray sensor are respectively input over time, and the signal level and the foreign object are inputted over time. A device for inspecting foreign matter in shellfish shellfish, comprising: second discrimination means for determining the presence or absence of foreign matter in shellfish shellfish by comparing the size with a predetermined threshold value for detection. (2) A transport means for continuously transporting shellfish shells together with a transport fluid via a pipeline; and an X-ray irradiation means for irradiating X-rays to shellfish shells and the transport fluid passing through the pipeline. , an absorber disposed between the X-ray irradiation means and the pipeline and absorbing long wavelength components of part of the X-rays in the X-ray irradiation optical path; and a plurality of minute X-ray receiving elements installed in the pipe. A fluorescent substance sensitive to long wavelength X-rays is disposed on the upper surface of the fluorescent material, which is arranged in a straight line in a direction across the line and at a position to receive X-rays that do not pass through the absorbing material, a first one-dimensional X-ray sensor that receives X-rays via a pipeline; and a plurality of minute X-ray receiving elements that receive X-rays that pass through the absorbing material in a straight line in a direction that crosses the pipeline. a fluorescent substance sensitive to short wavelength X-rays is disposed on the upper surface thereof, and a second one receives the X-rays from the X-ray irradiation means through an absorbing material and a pipeline. A peeled shellfish medium comprising: a dimensional X-ray sensor; and a determining means for determining the presence or absence of foreign matter in the shellfish based on the signal levels of the first and second one-dimensional sensors, respectively. foreign matter inspection equipment. (3) The determining means sequentially inputs the signal levels of the individual X-ray light receiving elements of the first one-dimensional X-ray sensor at a predetermined cycle time, and compares the relative magnitudes of each signal level. The signal levels of the first discriminating means for discriminating the presence or absence of foreign matter in the shellfish shellfish and the individual X-ray receiving elements of the second one-dimensional X-ray sensor are respectively input over time, and the signal level and The method of peeling shellfish according to claim 2, further comprising a second determining means for determining the presence or absence of a foreign object in the shellfish by comparing the size with a predetermined threshold value for foreign object detection. A device for inspecting foreign substances in the body.