JP5654252B2 - X-ray inspection equipment - Google Patents

Description

  The present invention relates to an X-ray inspection apparatus that irradiates an inspection object with X-rays and detects foreign matter in the inspection object.

  Conventionally, an X-ray inspection apparatus or the like has been used to detect foreign matter in an inspection object. R & D is being conducted daily on these X-ray inspection apparatuses.

  For example, Patent Document 1 discloses an X-ray inspection apparatus. The X-ray inspection apparatus includes an X-ray source that irradiates an inspection object with X-rays, an X-ray detection means that detects an amount of X-rays transmitted through each part of the inspection object, and an X-ray detection means An X-ray inspection apparatus comprising: an image generation unit that generates an X-ray image corresponding to an amount of X-ray transmission based on detection information; and a display unit that displays an X-ray image generated by the image generation unit. A region extraction unit that extracts a part of detection information from the X-ray detection unit and causes the image generation unit to generate an X-ray image of a physical quantity measurement region excluding at least a portion corresponding to the background of the X-ray image; and region extraction A physical quantity calculation means for calculating a physical quantity corresponding to the size or mass of the object to be inspected based on the detection information extracted by the means; an X-ray image of the physical quantity measurement region; and a graph display showing the physical quantity calculated by the physical quantity calculation means Display in the display means in association with the element And a display control means for.

  In the above X-ray inspection apparatus, detection information in a predetermined detection level range is extracted from detection information from the X-ray detection means to generate an X-ray image of a physical quantity measurement region, and the extracted detection information is included in the extracted detection information. Based on this, physical quantity calculation for calculating a physical quantity corresponding to the size or mass of the object to be inspected is executed, and an X-ray image of the physical quantity measurement region and a graph display element indicating the calculated physical quantity are displayed in association with each other. . Accordingly, it is possible to effectively display the data related to the calculation of the physical quantity in the X-ray image data, and to easily display the physical quantity calculation result associated with the X-ray image corresponding thereto.

JP 2006-308467 A

  However, in the conventional X-ray inspection apparatus, the X-rays irradiated from the X-ray source pass through the inspection object and the conveyance path (belt conveyor), so that X depends on the thickness and state of the conveyance path. The reliability of the inspection object information in the line transmission image is lowered.

  An object of the present invention is to provide an X-ray inspection apparatus capable of obtaining accurate gradation information of an inspection object.

  Another object of the present invention is to provide an X-ray inspection apparatus capable of performing accurate weight estimation and rank determination of an inspection object.

(1) An X-ray inspection apparatus according to one aspect is an X-ray inspection apparatus that inspects an object to be inspected conveyed by a conveyance unit using X-rays irradiated from an X-ray source. A detector that generates X-rays by detecting X-rays that have been irradiated and transmitted through the object to be inspected, and gradation information that corresponds to the transport unit on which the object to be inspected is placed from the detection data corresponding to the object to be inspected And a correction unit that performs correction for adjusting. The correction unit performs correction according to the position in the direction orthogonal to the conveyance direction of the inspection object and the position in the conveyance direction of the inspection object.

  In the X-ray inspection apparatus according to one aspect, X-rays that have passed through the inspection object are detected by a detector, and detection data is generated by the detector. Correction that adjusts (decreases) the gradation information corresponding to the transport unit on which the inspection object is placed is performed by the correction unit from the detection data corresponding to the inspection object.

  In this case, accurate gradation information corresponding to the inspection object is obtained by performing correction for subtracting gradation information corresponding to the transport unit on which the inspection object is placed from the detection data corresponding to the inspection object. be able to. Therefore, it is possible to accurately perform the weight estimation and rank determination processing of the inspection object based on the corrected gradation information.

(2) It is preferable that the correction unit performs correction according to the transport position in a direction orthogonal to the transport direction of the inspection object.

  In this case, X-rays from the X-ray source are emitted radially to the transport unit. For this reason, there are X-rays that enter perpendicularly to the surface of the transport unit and there are X-rays that enter at an angle, so that the X-rays correspond to the transport position in the direction orthogonal to the transport direction of the inspection object The transmission distance is different. In addition, when a belt conveyor is used as the transport unit, the thickness in a region where a belt joint portion or the like exists is larger than that in other regions, and therefore the X-ray transmission distance in the region is also different.

  Therefore, even if the X-ray transmission distance varies depending on the transport position, accurate gradation information of the inspection object can be obtained by performing correction according to the transport position. Thereby, the weight estimation and rank determination processing of the inspection object can be performed with high accuracy.

(3) It is preferable that the X-ray inspection apparatus further includes a storage unit that stores in advance a correction amount by the correction unit, and the correction unit corrects the detection data using the correction amount stored in the storage unit.

  In this case, for example, the thickness of the transport unit corresponding to each transport position in a direction orthogonal to the transport direction of the inspection object is recognized in advance. That is, by recognizing the thickness of the transport unit, the X-ray transmission distance for each transport position can be grasped, and the noise component for each transport position can be grasped. Thereby, the correction amount by the correction unit can be determined in advance. Then, the correction amount is stored in the storage unit. Since the detection data is corrected based on the stored correction amount, accurate gradation information of the inspection object can be obtained.

(4) The transport unit may be a belt conveyor, the X-ray inspection apparatus may further include an encoder that detects the amount of movement of the belt conveyor, and the correction unit may reset the correction amount based on the detection result of the encoder. preferable.

  In this case, by detecting the amount of movement of the belt conveyor by the encoder, it becomes possible to recognize whether or not the belt conveyor has made one turn. Therefore, correction can be performed using an appropriate correction amount based on the transport position by resetting the correction amount every time the belt conveyor makes one round. Thereby, accurate gradation information of the inspection object can be obtained.

(5) The X-ray inspection apparatus includes a weight estimation unit that estimates the weight of the inspection object based on the gradation information of the detection data corrected by the correction unit, and the weight of the inspection object estimated by the weight estimation unit. A rank determination unit that determines which class among a plurality of classes set in advance may be further included.

  In this case, the weight estimation unit estimates the weight of the inspection object based on the gradation information of the detection data corrected by the correction unit. The rank determination unit determines which of the plurality of preset classes the estimated weight of the inspection object belongs to.

  Therefore, as described above, accurate gradation information of the inspection object can be obtained by the correction by the correction unit, so that the weight estimation of the inspection object by the weight estimation unit and the rank determination of the inspection object by the rank determination unit can be performed. Increases accuracy.

  According to the X-ray inspection apparatus according to the present invention, the correction is performed by subtracting the gradation information corresponding to the transport unit on which the inspection object is placed from the detection data corresponding to the inspection object, thereby correcting the inspection object. Corresponding accurate gradation information can be obtained.

1 is a schematic external view showing an example of an X-ray inspection apparatus according to the present embodiment. It is a schematic diagram which shows an example of the internal structure of the X-ray inspection apparatus which concerns on this embodiment. It is a block diagram which shows the structure part in connection with an image process in an X-ray inspection apparatus. It is explanatory drawing for demonstrating an X-ray transmissive distance and an X-ray detection value. It is explanatory drawing for demonstrating the correction amount used at the time of the correction process by a correction | amendment part. It is a schematic diagram which shows the example of a display of a weight estimation result. It is a graph which shows the comparison of the weight estimation result in the case of correction non-execution and correction implementation. It is explanatory drawing for demonstrating the corrected amount which concerns on another example.

  Hereinafter, an X-ray inspection apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic external view showing an example of the X-ray inspection apparatus 100 according to the present embodiment, and FIG. 2 is a schematic view showing an example of the internal structure of the X-ray inspection apparatus 100 according to the present embodiment.

  As shown in FIG. 1, the X-ray inspection apparatus 100 has an X-ray inspection chamber 300 formed therein. An X-ray irradiation apparatus 200 is built in the X-ray examination room 300. A belt conveyor 800 is provided so as to penetrate the X-ray examination room 300.

  An X-ray leakage prevention curtain 500 that prevents X-ray leakage from the opening of the X-ray examination room 300 is provided. In addition, the X-ray inspection apparatus 100 is provided with a touch panel type input display unit MT for an operator to operate. The operator drives the X-ray inspection apparatus 100 by operating the input display unit MT. In addition, the worker places the inspection object 900 (FIG. 2) on the belt conveyor 800.

  In the present embodiment, for the inspected object 900 placed on the belt conveyor 800, weight estimation and rank determination as to which class among the plurality of classes the estimated weight belongs to are performed.

  As shown in FIG. 2, the X-ray examination room 300 mainly includes an X-ray irradiation apparatus 200, a line sensor 220, an X-ray leakage prevention curtain 500, and a belt conveyor 800. The X-ray leakage prevention curtain 500 includes an X-ray leakage prevention curtain 510 on the entrance side of the X-ray examination room 300 and an X-ray leakage prevention curtain 520 on the exit side.

  The belt conveyor 800 is configured by winding an endless belt around a pair of rollers. A line sensor 220 that includes a scintillator and a photodiode element and detects X-rays is provided inside the belt conveyor 800. The line sensor 220 includes a plurality of detection elements (detection elements 220a and 220b described later) that detect X-rays. In addition, the X-ray inspection apparatus 100 includes an encoder 101 that detects the amount of movement of the belt conveyor 800.

  In FIG. 2, the inspection object 900 is placed on the belt conveyor 800. When the belt conveyor 800 is driven, the inspection object 900 is transported along the direction of the arrow d1 (hereinafter referred to as the transport direction d1). The inspection object 900 being transported first passes through the X-ray leakage prevention curtain 510 and moves into the X-ray inspection room 300.

  Next, X-rays 210 are irradiated from the X-ray irradiation apparatus 200 to the inspection object 900 being conveyed. Then, the X-ray 210 that has passed through the inspection object 900 enters the line sensor 220.

  The line sensor 220 generates detection data based on the incident X-ray 210. Based on the detection data generated by the line sensor 220, weight estimation and rank determination are performed.

  Thereafter, the inspection object 900 is continuously conveyed by the belt conveyor 800, and then moves outside the X-ray inspection chamber 300 after passing through the X-ray leakage prevention curtain 520. Then, the inspection object 900 is conveyed to the next process.

  3 is a block diagram showing components related to image processing in the X-ray inspection apparatus 100, FIG. 4 is an explanatory diagram for explaining an X-ray transmission distance and an X-ray detection value, and FIG. FIG. 6 is an explanatory diagram for explaining a correction amount HR used in the correction process by FIG. 6, and FIG. 6 is a schematic diagram showing a display example of a weight estimation result.

  As shown in FIG. 3, the X-ray inspection apparatus 100 according to the present embodiment includes the above-described line sensor 220, A / D converter 230, processing unit FS, and above-described input display unit MT as components related to image processing. Prepare.

  The processing unit FS includes a luminance data acquisition unit 240, a summation unit 250, a correction unit 260, a storage unit 261, a weight estimation unit 270, a rank determination unit 280, and a display data creation unit 290. Each component of the processing unit FS is functionally realized by a CPU (Central Processing Unit) executing a processing program stored in a RAM (Random Access Memory) or a ROM (Read-Only Memory). . Such a processing program can be installed from a recording medium such as a CD-ROM or DVD-ROM in which the processing program is recorded, or can be downloaded from a server via a network.

  In FIG. 3, first, X-rays 210 that have passed through the inspection object 900 are incident on the line sensor 220, and the line sensor 220 generates detection data KDa that is analog data based on the X-rays 210. The detection data KDa is converted into detection data KDd which is digital data by the A / D converter 230.

  The brightness data LD1 is acquired by the brightness data acquisition unit 240 based on the detection value of the detection data KDd. The luminance data LD1 corresponds to one line of the image. Then, the luminance data LD2 corresponding to all lines of the image is generated by adding the plurality of luminance data LD1 by the adding unit 250.

  As shown in FIG. 4 (a), a plurality of detection elements 220a of the line sensor 220 along a direction d2 (hereinafter referred to as an element arrangement direction) d2 orthogonal to the conveyance direction d1 of the inspection object 900 (FIG. 2). , 220b. In FIG. 4A, only two detection elements 220a and 220b are shown for convenience of explanation.

  In the present embodiment, correction is performed by subtracting gradation information corresponding to the belt conveyor 800 on which the inspection object 900 is placed from gradation information (luminance information) corresponding to the inspection object 900 in the luminance data LD2. This is performed by the unit 260.

  Here, the transmission distance of the X-rays 210 irradiated from the X-ray irradiation apparatus 200 differs depending on the position in the element arrangement direction d2. That is, when the irradiation distance h of the X-ray 210 detected by the detection element 220a of the line sensor 220 is compared with the irradiation distance H (= h / cos α) of the X-ray 210 detected by the detection element 220b, the irradiation distance H Is longer than the irradiation distance h. Therefore, the X-ray 210 detected by the detection element 220b is longer than the X-ray 210 detected by the detection element 220a with respect to the distance (hereinafter referred to as the transmission distance) through which the X-ray 210 passes through the belt conveyor 800. Become. Note that α is a vertical line (h) connecting the X-ray irradiation apparatus 200 and the center position of the detection element 220a and a straight line (H) connecting the X-ray irradiation apparatus 200 and the center position of the detection element 220b. It is an angle to make.

  As a result, the transmission distance of the X-ray 210 increases as the distance from the center position of the line sensor 220 increases. Therefore, as shown in FIG. 4B, when the ideal line K0 indicating the detection value of the line sensor 220 when the transmission distance of the X-ray 210 is uniform at each position in the element arrangement direction d2, the line is A detection value curve K1 indicating an actual detection value by the sensor 220 has a convex shape in which the X-ray transmission amount at both ends of the line sensor 220 is lower than the X-ray transmission amount of the ideal line K0 at the same position. In addition, the noise curve K2 indicating the noise component is concave, contrary to the detection value curve K1.

  Thus, the amount of X-ray transmission detected varies depending on the position in the element arrangement direction d2 (the positions of the detection elements 220a and 220b of the line sensor 220). Therefore, in the present embodiment, as will be described below, correction by the correction unit 260 is performed according to the position in the element arrangement direction d2.

  As shown in FIG. 5, the correction unit 260 (FIG. 3) performs correction using the correction amount HR. Accordingly, although the X-ray transmission distance is actually different at each position in the element arrangement direction d2, the X-ray transmission distance is uniform over the element arrangement direction d2 by performing correction using the correction amount HR. Can be reproduced. Thereby, accurate gradation information of the inspection object 900 can be obtained.

  Here, in FIG. 5, when the horizontal axis is the position in the element arrangement direction d2, and the vertical axis is the magnitude of the correction amount, the curve of the correction amount HR is corrected at both ends with respect to the center in the element arrangement direction d2. Concave type with increased amount. The correction amount HR is determined based on the thickness of the belt conveyor 800 corresponding to the position in the element arrangement direction d2 and the X-ray transmission distance resulting from the thickness. In the present embodiment, considering the detection value curve K1 and the noise curve K2 in FIG. 4B, the correction amount HR is a concave curve that is gentler than the noise curve K2 so that the detection value curve K1 approaches the ideal line K0. To do.

  In the correction using the correction amount HR corresponding to each position in the element arrangement direction d2, the correction amount HR is reset every time the belt conveyor 800 makes one turn based on the detection result of the encoder 101. . Accordingly, correction can be performed using an appropriate correction amount HR corresponding to each position in the element arrangement direction d2.

  Subsequently, the weight of the inspection object 900 is estimated by the weight estimation unit 270 (FIG. 3) based on the gradation information of the corrected data HD by the correction unit 260. As shown in FIG. 6, the weight of the inspection object 900 estimated by the weight estimation unit 270 is displayed, for example, in the display region R1 of the input display unit MT.

  An example of the weight estimation method by the weight estimation unit 270 is as follows. Each of the detection elements (detection elements 220a, 220b, etc.) of the line sensor 220 transmits, for example, 256 detection gradations in which the highest luminance white is “255” and the lowest luminance black is “0”. The brightness corresponding to the X-ray is detected. In the present embodiment, for example, the weight estimation unit 270 determines the brightness (belt conveyor) in a state where the inspection object 900 is not placed from the brightness where the inspection object 900 is placed on the belt conveyor 800. The estimated weight of the inspected object 900 is calculated by reducing the brightness of only 800).

  Further, the rank determination unit 280 (FIG. 3) determines which class of the plurality of predetermined classes the weight of the inspection object 900 estimated by the weight estimation unit 270 belongs to. Further, the display data creation unit 290 creates display data for display on the input display unit MT.

  An example of a rank determination (class determination) method by rank determination unit 280 is as follows. Based on the estimation result by the weight estimation unit 270, the rank determination unit 280 is set in advance for each weight class (the type of the inspection object 900 within a predetermined range, for example, If it is determined whether it belongs to 5 levels (classified into SS, S, M, L and LL) or the object 900 does not belong to any of the above weight classes, The inspection object 900 is determined to be abnormal.

  More specifically, it is as follows. An upper limit value and a lower limit value of a target range (allowable range) for each weight class are set in advance for each type of inspection object 900. The rank determination unit 280 compares the estimated weight described above with the upper limit value and lower limit value of each of the weight classes, and determines whether the estimated weight falls below the upper limit value and above the lower limit value of any weight class. Determine. When it is determined that the estimated weight is within the range from any lower limit value to the upper limit value, it is determined that the weight of the inspection object 900 belongs to the weight class. On the other hand, when the estimated weight does not belong to any weight class, the rank determination unit 280 determines that the weight of the inspection object 900 is abnormal.

  The rank determination unit 280 may perform rank determination by including the shape of the inspection object 900 using the image data obtained by the X-ray inspection apparatus 100 in the weight class based on the estimated weight. For example, if the inspected object 900 has a symmetrical shape, the rank grade can be increased. If the inspected object 900 has a left-right asymmetrical non-uniform shape, the rank grade can be decreased. can do.

(Effect in this embodiment)
In the present embodiment, the correction unit 260 performs correction to subtract gradation information corresponding to the belt conveyor 800 on which the inspection object 900 is placed from gradation information corresponding to the inspection object 900. In this case, accurate gradation information corresponding to the inspection object 900 is obtained by correcting the gradation information of the inspection object 900 by subtracting the gradation information of the belt conveyor 800 on which the inspection object 900 is placed. Can be obtained. Therefore, it is possible to accurately perform the weight estimation and rank determination processing of the inspection object 900 based on such corrected gradation information. Hereinafter, an example of the effect will be described.

  FIG. 7 is a graph showing a comparison of weight estimation results when correction is not performed and when correction is performed.

  As shown in FIG. 7A, when the correction by the correction unit 260 is not performed, there is a significant variation in the weight estimation result of the inspection object 900. On the other hand, when the correction by the correction unit 260 is performed, as shown in FIG. 7B, variation in the weight estimation result of the inspection object 900 is remarkably reduced. Thus, it can be seen that the weight estimation accuracy is improved by the correction by the correction unit 260.

  Further, X-rays 210 from the X-ray irradiation apparatus 200 are irradiated radially onto the belt conveyor 800. Therefore, as described above, there are X-rays 210 that are incident perpendicularly to the surface of the belt conveyor 800 and X-rays 210 that are incident obliquely, so that depending on the position in the element arrangement direction d2. The transmission distance of the X-ray 210 is different.

  Therefore, in this embodiment, accurate gradation information of the inspection object 900 can be obtained by performing correction using the correction amount HR corresponding to each position in the element arrangement direction d2. Thereby, the process of weight estimation and rank determination of the inspection object 900 can be performed with higher accuracy.

  In addition, since the correction amount HR considering the thickness of the belt conveyor 800 and the X-ray transmission distance is stored in the storage unit 261, the thickness is updated even when the thickness of the belt conveyor 800 changes over time. Thus, the subsequent correction process can be performed accurately.

  Further, each time the belt conveyor 800 makes one turn, the correction amount HR is reset, so that correction can be performed using an appropriate correction amount HR corresponding to the element arrangement direction d2. Thereby, accurate gradation information of the inspection object 900 can be obtained.

(Correspondence between each component of claims and each part of the embodiment)
In the above embodiment, the X-ray inspection apparatus 100 corresponds to the X-ray inspection apparatus, the X-ray irradiation apparatus 200 corresponds to the X-ray source, the inspection object 900 corresponds to the inspection object, and the X-ray 210 corresponds to the X-ray. The belt conveyor 800 corresponds to the conveyance unit, the detection data KDa and KDd and the brightness data LD1 and LD2 correspond to the detection data, the line sensor 220 corresponds to the detector, and the correction unit 260 corresponds to the correction unit. The transport direction d1 corresponds to the transport direction of the inspection object, the element disposition direction d2 corresponds to the direction orthogonal to the transport direction, the correction amount HR corresponds to the correction amount, and the storage unit 261 stores the storage unit The encoder 101 corresponds to the encoder, the weight estimation unit 270 corresponds to the weight estimation unit, and the rank determination unit 280 corresponds to the rank determination unit.

(Modification)
As described above, the X-ray transmission distance varies depending on the thickness of the belt (not shown) of the belt conveyor 800. For example, foreign matter such as dust on the belt or one or more markers attached to the belt. Is present, it is preferable to determine the correction amount HR in consideration of these. Thereby, more accurate gradation information of the inspection object 900 can be obtained.

  In the above embodiment, the correction amount HR is reset based on the detection result of the encoder 101. However, the present invention is not limited to this. For example, a mark is attached on the belt conveyor 800, The correction amount HR may be reset based on the detection of the mark.

  In the above embodiment, correction is performed using the correction amount HR corresponding to each position in the element arrangement direction d2. However, as shown in FIG. 8, the conveyance direction d1 (flow direction) is also taken into consideration. Correction may be performed using the correction amount HR1. For example, since the joint portion of the belt of the belt conveyor 800 is thicker than other portions, the correction amount HR is uniformly increased when estimating the weight of the inspection object 900 placed on the joint portion. The weight estimation accuracy is further improved by using the curve of the corrected amount HR1.

  In the above embodiment, the curve of the correction amount HR (FIG. 5) is a gentle concave shape. However, the present invention is not limited to this, and various conditions such as the thickness of the belt conveyor 800 and the X-ray transmission distance can be obtained. In view of this, the correction amount HR can be set as appropriate.

  Furthermore, although one preferable embodiment of the present invention is as described above, the present invention is not limited thereto. It will be understood that various other embodiments may be made without departing from the spirit and scope of the invention. Furthermore, in this embodiment, although the effect | action and effect by the structure of this invention are described, these effect | actions and effects are examples and do not limit this invention.

DESCRIPTION OF SYMBOLS 100 X-ray inspection apparatus 101 Encoder 200 X-ray irradiation apparatus 210 X-ray 220 Line sensor 220a, 220b Detection element 260 Correction | amendment part 261 Memory | storage part 270 Weight estimation part 280 Rank determination part 800 Belt conveyor 900 Test object d1 Conveyance direction d2 Element arrangement Installation direction HR, HR1 Correction amount KDa, KDd Detection data LD1, LD2 Brightness data MT Input display

Claims (4)

An X-ray inspection apparatus that inspects an object to be inspected conveyed by a conveyance unit using X-rays emitted from an X-ray source,
A detector that generates detection data by detecting X-rays irradiated from the X-ray source and transmitted through the inspection object;
A correction unit that performs correction to adjust gradation information corresponding to the transport unit on which the inspection object is placed from the detection data corresponding to the inspection object;
Equipped with a,
The X-ray inspection apparatus, wherein the correction unit performs the correction in accordance with a position in a direction orthogonal to a conveyance direction of the inspection object and a position in the conveyance direction of the inspection object. A storage unit that stores in advance a correction amount by the correction unit;
The correction unit corrects the detection data using the correction amount stored in the storage unit.
The X-ray inspection apparatus according to claim 1 . The transport unit is a belt conveyor,
An encoder for detecting the amount of movement of the belt conveyor;
The correction unit resets the correction amount based on a detection result of the encoder.
The X-ray inspection apparatus according to claim 1 or 2 . A weight estimation unit that estimates the weight of the object to be inspected based on gradation information of detection data after correction by the correction unit;
A rank determination unit for determining whether a weight of the inspection object estimated by the weight estimation unit belongs to which class among a plurality of classes set in advance; Do
The X-ray inspection apparatus according to any one of claims 1 to 3 .