JP2007132796A - X-ray inspection device and x-ray inspection program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray inspection device equipped with a feed part constituted by combining feed plates arranged so as to leave a predetermined gap in a feed direction and capable of executing calibration of high precision without accompanying troublesome work or cost-up. <P>SOLUTION: In the X-ray inspection device for performing inspection while feeding a commodity G by rotating a plurality of feed plates 12a arranged so as to leave a predetermined gap X in a feed direction, the calibration for adjusting the detection sensitivity of X-rays at every pixel in an X-ray line sensor 14 is performed so that the detection signals corresponding to the number of lines corresponding to one pitch or above of the feed plates 12a is acquired in the X-ray line sensor 14 and the detection sensitivity of the X-ray line sensor 14 is corrected using the correction factor calculated on the basis of the acquired detection signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an X-ray inspection apparatus equipped with a plate conveyor arranged at a predetermined interval in the transport direction.

  Conventionally, in the production line of products such as food, in order to prevent the defective product from being shipped when foreign matter is mixed into the product or the product is cracked or broken, the product has failed using an X-ray inspection device. Inspection is being conducted. In this X-ray inspection apparatus, X-rays are irradiated to an object to be inspected continuously conveyed by a conveyer, the X-ray transmission state is detected by an X-ray light receiving unit, and foreign matter is detected in the object to be inspected. It is determined whether there is no contamination, whether the inspection object is cracked or missing, or whether the quantity of unit contents in the inspection object is insufficient. Moreover, the X-ray inspection apparatus may perform an inspection for counting the number of unit contents in the inspection object.

In such an X-ray inspection apparatus, when inspecting a spherical article such as an egg that is easy to roll, the X-ray inspection apparatus is arranged with a predetermined gap in the conveyance direction in order to make the article stationary on the conveyor. There is also a device that performs inspection while moving a plurality of transfer plates in the transfer direction.
For example, in the X-ray inspection apparatus disclosed in Patent Document 1, a plurality of mounting plates (conveying plates) attached to the surface of a conveyor are combined to form irregularities, which are used in a boiled egg production / processing line. .
JP 2004-125673 A (published on April 22, 2004)

However, the conventional X-ray inspection apparatus has the following problems.
That is, in the X-ray inspection apparatus disclosed in the above-mentioned publication, high-precision calibration is performed by a normal method because the thickness of the mounting plate is not uniform and a gap is interposed between the plurality of mounting plates. I can't do it. For this reason, in order to perform highly accurate calibration, it is necessary to perform calibration by forming a state where there is no mounting plate between the irradiation unit and the light receiving unit. It was necessary to make the transport speed extremely slow, which was very troublesome.

In addition, a sensor that detects the presence or absence of a mounting plate may be provided between the irradiation unit and the light receiving unit, and calibration may be performed when there is no mounting plate while performing normal conveyance. However, in this case, it is necessary to provide a sensor for detecting the mounting plate, which causes a cost increase.
An object of the present invention is to provide an X-ray inspection apparatus including a transport unit configured by combining transport plates arranged with a predetermined gap in the transport direction, without a troublesome work and cost increase. An object of the present invention is to provide an X-ray inspection apparatus and an X-ray inspection program capable of performing accurate calibration.

  An X-ray inspection apparatus according to a first invention is an X-ray inspection apparatus that inspects an article by irradiating the article to be conveyed with X-rays and detecting X-rays transmitted through the article. Unit, a light receiving unit, a transport unit, and a control unit. The irradiation unit irradiates the article with X-rays. The light receiving unit detects X-rays emitted from the irradiation unit. The conveyance unit conveys the article in a predetermined direction by moving, in the conveyance direction, a plurality of conveyance plates arranged with a predetermined gap in the conveyance direction of the article between the irradiation unit and the light receiving unit. The control unit acquires detection signals in the light receiving unit for a plurality of lines corresponding to one pitch or more in the transport direction of the transport plate while moving the transport plate in the transport direction. And a control part correct | amends the detection sensitivity of the X-ray in a light-receiving part based on the detection signal for several lines.

  Here, in an X-ray inspection apparatus that performs inspection while moving an object to be inspected in a predetermined direction by moving a plurality of transport plates arranged at predetermined intervals in the transport direction, a light receiving unit such as a line sensor The detection signal, which is the reference for calibration (correction of detection sensitivity of each pixel included in the light receiving unit) to adjust the X-ray detection sensitivity of each pixel, is usually performed without manually moving the position of the transport plate. Acquired while maintaining the transport state.

  Specifically, the control unit causes the light receiving unit to acquire detection signals for lines corresponding to one pitch or more in the transport direction of the transport plate while maintaining the X-ray irradiation and the transport state in the transport unit. And a control part specifies the detection signal in the light-receiving part in the state which has not passed the conveyance plate based on the detection signal for the said multiple lines, and the detection sensitivity in a light-receiving part based on the detection signal specified here Correction (calibration).

  Usually, in such an X-ray inspection apparatus having a transport unit in which a plurality of transport plates are arranged at a predetermined pitch with a predetermined interval, the X is measured when the transport plate passes and when the transport plate does not pass. Because there is a large difference in the amount of lines, in order to carry out highly accurate calibration, the conveyance can be adjusted manually so that there is a gap between the conveyance plates between the irradiation unit and the light receiving unit. It is necessary to move the speed or to extremely slow the conveying speed than usual.

  In the X-ray inspection apparatus of the present invention, detection signals for lines corresponding to one pitch or more in the transport direction of the transport plate are acquired in the light receiving unit, and this average value is calculated and acquired without using the transport plate. The detection signal is specified. That is, among the detection signals acquired for a plurality of lines corresponding to one pitch or more in the transport direction, for example, the brightest on the X-ray image formed by image processing the detection signals for the plurality of lines (the X-ray detection level is The (high) line detection signal is identified as a detection signal that does not pass through the transport plate.

  As a result, even when the transport unit is configured by combining a plurality of transport plates arranged with a predetermined gap, the transport plate can be adjusted so that the gap portion of the transport plate is between the irradiation unit and the light receiving unit. Without manually moving the transport plate, it is possible to acquire a detection signal in a state where the normal transport state is maintained and not through the transport plate, and to perform highly accurate calibration.

An X-ray inspection apparatus according to a second invention is the X-ray inspection apparatus according to the first invention, wherein the control unit is configured to carry the detection signal for a plurality of lines acquired in the light receiving unit for each line. A statistical value representing the signal magnitude of one line in the direction orthogonal to the line is calculated.
Here, a statistical value (for example, an average value) representing the magnitude of the signal for one line of the detection signal in the direction orthogonal to the conveyance direction in the light receiving unit is calculated. That is, when the light receiving unit is a line sensor, a statistic value indicating the magnitude of a signal for one line of detection signals detected in a plurality of pixels arranged in a direction orthogonal to the conveyance direction is calculated.

Here, the statistical value representing the magnitude of the signal for one line includes, for example, the average value of the detection signals in the line, the smallest value, and the like.
Thus, even when the transport unit is slightly inclined with respect to the light receiving unit arranged long in the direction orthogonal to the transport direction, the statistical value indicating the signal magnitude for one line in the direction orthogonal to the transport direction By calculating, appropriate calibration can be performed.

An X-ray inspection apparatus according to a third invention is the X-ray inspection apparatus according to the first or second invention, and the control unit calculates an average value for a plurality of lines.
Here, for example, the average value of the detection signals for a plurality of lines is calculated in order from the brightest (highest X-ray detection level) on the X-ray image, and the detection signals acquired without going through the transport plate are averaged. To do.
Thereby, the detection signal used as the reference of calibration can be set to an appropriate value without variation. As a result, calibration with higher accuracy can be performed without troublesome work.

An X-ray inspection apparatus according to a fourth aspect of the present invention is the X-ray inspection apparatus according to any one of the first to third aspects of the present invention, wherein the control unit is the light receiving unit, and the X-ray irradiation and conveyance in the irradiation unit. A detection signal at the time of non-irradiation with X-rays is acquired when conveyance in the section is in a stopped state.
Here, a detection signal at the time of non-irradiation of X-rays acquired at the time of X-ray irradiation and conveyance stop is acquired as a detection signal serving as a reference for calibration.

Here, the detection signal at the time of non-irradiation with X-rays is acquired when the movement of the transfer plate in the transfer unit is in a stopped state, and the position of the transfer plate at the time of acquisition is a portion having a constant thickness or It suffices if the portion where the transport plate does not exist is disposed between the irradiation unit and the light receiving unit.
Thereby, more accurate calibration is performed based on the X-ray detection signal acquired in the absence of the transport plate and the detection signal at the time of non-irradiation X-rays acquired in the X-ray irradiation stop state. be able to.

  An X-ray inspection apparatus according to a fifth aspect is the X-ray inspection apparatus according to any one of the first to fourth aspects, wherein the control unit corrects the X-ray detection sensitivity in the light receiving unit. At this time, the conveyance speed in the conveyance unit is set to the same speed as that in the normal inspection.

Here, calibration is performed with the conveyance speed at the time of normal inspection being maintained. In the X-ray inspection apparatus of the present invention, the detection signal for calibration can be obtained at the normal conveyance speed without slowing down or stopping the conveyance speed.
Thereby, highly accurate calibration can be performed without complicated control, troublesome work, and cost increase.

  An X-ray inspection program according to a sixth invention includes an irradiation unit that irradiates an article with X-rays, a light receiving unit that detects X-rays emitted from the irradiation unit, and an article between the irradiation unit and the light receiving unit. An X-ray inspection apparatus comprising: a transport unit configured to transport an article in a predetermined direction by moving a plurality of transport plates arranged in a transport direction in a state where a predetermined gap is left in the transport direction of A line inspection program for causing a computer to execute an X-ray inspection method including the following steps. In the first step, detection signals in the light receiving unit are acquired for a plurality of lines corresponding to one pitch or more in the transport direction of the transport plate while moving the transport plate in the transport direction. In the second step, the X-ray detection sensitivity in the light receiving unit is corrected based on the detection signal calculated for each line.

  Here, in an X-ray inspection program of an X-ray inspection apparatus that performs inspection while moving an object to be inspected in a predetermined direction by moving a plurality of transport plates arranged at predetermined intervals in the transport direction, Manually move the position of the transport plate with a detection signal that serves as a reference for calibration (correction of detection sensitivity of each pixel included in the light receiving unit) to adjust the X-ray detection sensitivity of each pixel in the light receiving unit such as a sensor. Acquired while maintaining the normal transport state without any.

  Specifically, a detection signal for a line corresponding to one pitch or more in the transport direction of the transport plate is acquired in the light receiving unit in the X-ray irradiation and the transport state in the transport unit. Based on the detection signals for the plurality of lines, a detection signal in the light receiving unit in a state where it does not pass through the transport plate is specified, and correction (calibration) of detection sensitivity in the light receiving unit is performed based on the detection signal specified here. ).

  Usually, in such an X-ray inspection apparatus having a transport unit in which a plurality of transport plates are arranged at a predetermined pitch with a predetermined interval, the X is measured when the transport plate passes and when the transport plate does not pass. Because there is a large difference in the amount of lines, in order to carry out highly accurate calibration, the conveyance can be adjusted manually so that there is a gap between the conveyance plates between the irradiation unit and the light receiving unit. It is necessary to move the speed or to extremely slow the conveying speed than usual.

  In the X-ray inspection program of the present invention, detection signals for lines corresponding to one pitch or more in the transport direction of the transport plate are acquired in the light receiving unit, and this average value is calculated and acquired without using the transport plate. The detection signal is specified. That is, among the detection signals acquired for a plurality of lines corresponding to one pitch or more in the transport direction, for example, the detection signal of the brightest line (high X-ray detection level) on the X-ray image is detected without passing through the transport plate. Identify as a signal.

  As a result, even when the transport unit is configured by combining a plurality of transport plates arranged with a predetermined gap, the transport plate can be adjusted so that the gap portion of the transport plate is between the irradiation unit and the light receiving unit. Without manually moving the transport plate, it is possible to acquire a detection signal in a state where the normal transport state is maintained and not through the transport plate, and to perform highly accurate calibration.

  According to the X-ray inspection apparatus of the present invention, the normal conveyance state is maintained without adjusting the gap portion of the conveyance plate to be between the irradiation unit and the light receiving unit or manually moving the conveyance plate. It is possible to acquire a detection signal in a state where the conveyance plate is not passed as it is, and to perform highly accurate calibration.

An X-ray inspection apparatus according to an embodiment of the present invention will be described below with reference to FIGS.
[Configuration of X-ray inspection apparatus 10 as a whole]
As shown in FIG. 1, the X-ray inspection apparatus 10 of the present embodiment is one of apparatuses that perform quality inspection in a production line for products such as food. The X-ray inspection apparatus 10 irradiates X-rays to products that are continuously conveyed, and inspects whether or not foreign substances are mixed in the products based on the X-ray dose that has passed through the products.

  This embodiment demonstrates the case where the egg-shaped goods G are used as a to-be-inspected object. As shown in FIG. 2, the commodity G is conveyed to the X-ray inspection apparatus 10 by the front conveyor 60. The product G is determined by the X-ray inspection apparatus 10 for the presence or absence of contamination. The determination result in the X-ray inspection apparatus 10 is transmitted to a distribution mechanism 70 disposed on the downstream side of the X-ray inspection apparatus 10. The distribution mechanism 70 sends the product G to the regular line conveyor 80 as it is when the product G is determined to be a non-defective product in the X-ray inspection apparatus 10. On the other hand, when the product G is determined to be a defective product in the X-ray inspection apparatus 10, the arm 70a having the downstream end as a rotation shaft rotates so as to block the conveyance path. As a result, the product G determined to be defective can be collected in the defective product collection box 90 arranged at a position off the conveyance path.

  Moreover, since the goods G are egg-shaped, they are easy to roll when transported by the transport unit 12. However, in the transport unit 12 mounted on the X-ray inspection apparatus 10 of the present embodiment, the transport of the product G is performed by combining a plurality of transport plates 12a arranged with a predetermined gap X (see FIG. 5) in the transport direction. I do. For this reason, it can be avoided that the product G gets stuck in the gap X between the transport plates 12a and the product G moves in the transport direction.

  As shown in FIG. 1, the X-ray inspection apparatus 10 mainly includes a shield box 11, a conveyor (conveying unit) 12, a shielding noren 16, and a monitor 26 with a touch panel function. As shown in FIG. 3, the shield box 11 has a conveyor 12, an X-ray irradiator (irradiating unit) 13, an X-ray line sensor (light receiving unit) 14, and a control computer (control unit) 20 (see FIG. 3). 4).

(Shield box 11)
The shield box 11 has a loading / unloading port 11a and a loading / unloading port 11b for loading and unloading the product on both the entrance side and the exit side of the product G. In this shield box 11, a conveyor 12, an X-ray irradiator 13, an X-ray line sensor 14, a control computer 20 (see FIG. 4) and the like are accommodated.

As shown in FIG. 1, the carry-in port 11 a and the carry-out port 11 b are blocked by a shield noren 16 in order to prevent leakage of X-rays to the outside of the shield box 11. This shielding nolen 16 has a rubber nolene portion containing lead, and is pushed away by the product when the product is carried in and out.
Further, in addition to the monitor 26, a key insertion slot and a power switch are arranged on the upper front portion of the shield box 11.

(Conveyor 12)
The conveyor 12 conveys the product G in a predetermined direction (see the arrow shown in FIG. 3) in the shield box 11, and is driven by a conveyor motor 12f included in the control block shown in FIG. The conveying speed of the conveyor 12 is finely controlled by the inverter 20 controlling the conveyor motor 12f by the control computer 20 so that the setting speed input by the operator is obtained.

  Moreover, the conveyor 12 has the conveyance plate 12a, the conveyor frame 12b, the opening part 12c, and the conveyor guide 12d, as shown in FIG. The conveyor 12 is attached to the shield box 11 in a removable state. Thus, for example, even when food is handled as an inspection target, the conveyor can be removed and frequently washed to keep the inside of the shield box 11 clean.

  As shown in FIG. 5, the transport plate 12a is a metallic plate having a width of 150 mm and arranged with a gap X of about 15 mm in the transport direction, the inner side of which is supported by the conveyor frame 12b. Yes. And by receiving the driving force of the conveyor motor 12f and rotating, the object placed on the transport plate 12a or in the gap between the transport plates 12a is transported in a predetermined direction.

The conveyor frame 12b supports the rotating transport plate 12a from its inner peripheral side, and has a long opening 12c in a direction orthogonal to the transport direction at a position facing the inner peripheral surface of the transport plate 12a. Have.
The opening 12c is formed on a line connecting the X-ray irradiator 13 and the X-ray line sensor 14 in the conveyor frame 12b. In other words, the opening 12c is formed in the X-ray irradiation region from the X-ray irradiator 13 in the conveyor frame 12b. As a result, the X-rays that have passed through the product G pass through the transport plate 12a or the gap therebetween, and are detected by the X-ray line sensor 14 without being shielded by the conveyor frame 12b.

  The conveyor guides 12d are disposed on both sides of the transport plate 12a that forms the transport path for the product G, and guide articles that move on the conveyor 12 so as not to deviate from the transport path. The conveyor guide 12d is attached in a state where it can be attached to and detached from the shield box 11 together with the conveyor 12. For this reason, even when food or the like is handled as an inspection target, the inside of the shield box 11 can always be kept clean by removing and cleaning the entire conveyor 12.

(X-ray irradiator 13)
As shown in FIG. 3, the X-ray irradiator 13 is disposed above the conveyor 12 and is disposed below the conveyor 12 through an opening 12c formed in the conveyor frame 12b. X-rays are irradiated in a fan shape toward 14 (see the hatched portion in FIG. 3). As a result, the X-ray dose transmitted through the commodity G conveyed on the X-ray line sensor 14 can be detected by the X-ray line sensor 14.

(X-ray line sensor 14)
The X-ray line sensor 14 is disposed below the conveyor 12 and detects X-rays that pass through the product G and the transport plate 12a. The X-ray line sensor 14 includes a plurality of pixels 14 a that are horizontally arranged in a straight line in a direction orthogonal to the conveying direction by the conveyor 12.
Further, the X-ray line sensor 14 transmits X-ray transmission amount data in each pixel 14 a for forming an X-ray image of the product G in plan view to the control computer 20. And in the control computer 20, based on the X-ray image formed by the said X-ray permeation | transmission amount, the foreign material mixing inspection etc. of the goods G are performed.

Further, the X-ray line sensor 14 adjusts the detection sensitivity error in each of the plurality of pixels 14a by calibration executed according to an X-ray inspection program described later. The calibration flow executed according to the X-ray inspection program will be described in detail later.
(Monitor 26)
The monitor 26 is a full dot display liquid crystal display. The monitor 26 has a touch panel function, and displays a screen for prompting parameter input relating to initial setting and defect determination, an inspection result of the product G, and the like.

(Control computer 20)
As shown in FIG. 4, the control computer 20 includes a CPU 21 and a ROM 22, a RAM 23, and a CF (Compact Flash (registered trademark), storage unit) 25 as a main storage unit controlled by the CPU 21. The CF 25 stores a file 25a for storing a detection signal at the time of non-irradiation of X-rays, which is a reference for calibration acquired when performing calibration described later, a file 25b for storing a detection signal, and the like. In the control computer 20, the CPU 21 reads various programs such as an X-ray inspection program stored in these storage units, and executes calibration.

The control computer 20 also includes a display control circuit that controls data display on the monitor 26, a key input circuit that captures key input data from the touch panel of the monitor 26, and an I / O for controlling data printing in a printer (not shown). USB 24 as an external input terminal is provided.
Storage units such as the CPU 21, ROM 22, RAM 23, and CF 25 are connected to each other via bus lines such as an address bus and a data bus.

The control computer 20 is connected to a conveyor motor 12f, a rotary encoder 12g, an X-ray irradiator 13, an X-ray line sensor 14, and the like.
The rotary encoder 12g is attached to the conveyor motor 12f, detects the conveying speed of the conveyor 12, and transmits it to the control computer 20.
The X-ray irradiator 13 is controlled by the control computer 20 to control X-ray irradiation timing, X-ray irradiation amount, X-ray irradiation prohibition, and the like.

The X-ray line sensor 14 transmits data corresponding to the X-ray dose detected at each pixel 14 a to the control computer 20.
<Calibration flow>
In the X-ray inspection apparatus 10 of the present embodiment, calibration for correcting the X-ray detection sensitivity for each pixel 14a included in the X-ray line sensor 14 is performed according to the flowchart shown in FIG.

That is, first, in step S <b> 1, the control computer 20 acquires a detection signal at the time of non-X-ray irradiation in the X-ray line sensor 14 with the X-ray irradiator 13 and the transport unit 12 stopped.
Next, in step S2, the control computer 20 starts X-ray irradiation from the X-ray irradiator 13, and in step S3 starts transfer (movement of the transfer plate 12a) in the transfer unit 12.

Next, in step S4, the control computer 20 uses the X-ray line sensor 14 to transfer one of the transfer plates 12a shown in FIG. Detection signals for the number of lines corresponding to the pitch or more are acquired.
In addition, 1 pitch of the conveyance plate 12a means the length which added the length (width) in the conveyance direction of the conveyance plate 12a, and the clearance gap X between the conveyance plates 12a, as shown to Fig.6 (a). . In this embodiment, the width of the transport plate 12a is set to 150 mm, and the gap X therebetween is set to 15 mm. For this reason, about 200 mm is set as the length corresponding to one pitch or more in the present embodiment. For this reason, the X-ray line sensor 14 repeatedly acquires detection signals for the number of lines corresponding to a length of 200 mm.

Further, the detection signal for one line acquired by the X-ray line sensor 14 refers to a detection signal acquired simultaneously by a plurality of pixels 14 a arranged in a direction orthogonal to the conveyance direction.
At this time, as shown in FIG. 6A, when the transport plate 12 a is interposed on a straight line connecting the X-ray irradiator 13 and the X-ray line sensor 14, before reaching the X-ray line sensor 14. The X-rays are attenuated by the transport plate 12a, and the detected X-ray detection signal becomes small. On the other hand, as shown in FIG. 6B, when there is a gap between the transport plate 12a on a straight line connecting the X-ray irradiator 13 and the X-ray line sensor 14, the X-ray line sensor 14 is almost attenuated. An X-ray detection signal is detected in a state in which it is not. For this reason, in order to perform highly accurate calibration, as shown in FIG. 6B, detection acquired in a state in which the transport plate 12a does not exist between the X-ray irradiator 13 and the X-ray line sensor 14. The signal is preferably used as a reference for obtaining a correction coefficient.

  In the X-ray inspection apparatus 10 of this embodiment, as described above, in step S4, detection signals for the number of lines corresponding to one pitch or more of the transport plate 12a are acquired. Thus, regardless of the timing at which the detection signal acquisition by the X-ray line sensor 14 is started, the acquired plurality of lines always include the gap X portion of the transport plate 12a. Therefore, by specifying a plurality of brightest lines (highest detection level) on the X-ray image among the plurality of lines including the gap X portion, the space between the X-ray irradiator 13 and the X-ray line sensor 14 is determined. The detection signal acquired in a state where there is a gap X can be specified.

For this reason, in the subsequent step S, the detection signal acquired through the gap X is specified, and processing using this as a reference for calculating the correction coefficient of the detection sensitivity for each pixel 14a is performed.
That is, in step S5, the average value of the detection signals in each pixel 14a included in one line of the detection signal acquired in step S4 is calculated. In other words, here, the average of the respective detection signals acquired in the pixels 14a of the X-ray line sensor 14 arranged long in the direction orthogonal to the transport direction is calculated, and this is used as the detection signal in that line. Thereby, even when the transport unit 12 and the X-ray line sensor 14 are arranged so as to be oblique to each other, an error between the plurality of pixels 14a arranged along the direction orthogonal to the transport direction is averaged. be able to.

  Next, in step S6, from the average value of each line calculated in step S5, 10 lines are identified in order from the brightest (highest detection level) on the X-ray image. An average value of the detection signals acquired in the line is calculated. Here, the average value for 10 lines that are the brightest (highest detection level) on the X-ray image is that the gap X of about 15 mm corresponds to 10 lines or more, and is acquired through the gap X. The detected signal is caused by being brighter (larger).

Next, in step S7, correction for each pixel 14a included in the X-ray line sensor 14 is performed based on the detection signal at the time of non-irradiation acquired in step S1 and the average value calculated in step S6. Calculate the coefficient.
Specifically, assuming that the pixel number is p, the detection signal level f (p) when X-rays are not irradiated, the detection signal level g (p) when X-rays are ON, and a preset reference level l, the sensitivity correction coefficient c (P) is calculated by the following relational expression (1).

c (p) = 1 / {g (p) -f (p)} (1)
Finally, in step S8, the detection sensitivity in each pixel 14a included in the X-ray line sensor 14 is corrected using the correction coefficient c (p) calculated in step S7.
Specifically, assuming the detection signal S (p) acquired during the inspection, the corrected signal level F (p) is calculated by the following relational expression (2).

F (p) = S (p) * c (p) (2)
In the X-ray inspection apparatus 10 of the present embodiment, by performing the calibration in the above-described procedure, a sensor for detecting the troublesomeness and the conveyance plate for adjusting the position of the conveyance plate before the calibration is provided. Therefore, it is possible to carry out highly accurate calibration without increasing the cost.

[Features of the X-ray inspection apparatus 10]
(1)
In the X-ray inspection apparatus 10 of the present embodiment, as shown in FIG. 3, inspection is performed while conveying a product G by rotating a plurality of conveyance plates 12 a arranged with a predetermined gap X in the conveyance direction. In the X-ray inspection apparatus 10, when performing calibration for adjusting the X-ray detection sensitivity for each pixel 14 a in the X-ray line sensor 14, the control computer 20 uses the transport in the transport unit 12 and the X-ray irradiator 13. X-ray irradiation is started, and detection signals for the number of lines corresponding to one pitch or more of the transport plate 12a are acquired by the X-ray line sensor 14 as shown in FIGS. 6 (a) and 6 (b). Then, the control computer 20 corrects the detection sensitivity of the X-ray line sensor 14 using the correction coefficient calculated based on the detection signal acquired here.

  Thereby, by acquiring detection signals for the number of lines corresponding to one pitch or more of the transport plate 12a, X-rays acquired through the gap X between the transport plates 12a in the acquired detection signal. Detection signals can be included. Then, the X-ray detection level of the detection signal acquired through the gap X should be larger (brighter on the X-ray image) than the detection levels acquired in other lines. Therefore, it is possible to specify the detection signal acquired through the gap X by specifying the brightest line on the X-ray image from the plurality of acquired lines. As a result, the detection signal specified here is used as a reference for calculating the correction coefficient, thereby detecting the trouble of adjusting the position of the transport plate 12a before calibration and the position of the transport plate 12a. High accuracy calibration can be performed by appropriately calculating a correction coefficient without increasing the cost for providing the sensor.

(2)
In the X-ray inspection apparatus 10 of the present embodiment, the control computer 20 detects the detection signals for the number of lines corresponding to one pitch or more of the transport plate 12a acquired by the X-ray line sensor 14 for each line. 14, the average value of the detection signals detected in the pixels 14 a included in 14 is calculated.

Here, the X-ray line sensor 14 acquires detection signals in a plurality of pixels 14 a arranged in a direction orthogonal to the transport direction.
Thereby, by calculating the average value of the detection signals acquired almost simultaneously in these pixels 14a, the X-ray line sensor 14 is arranged obliquely with respect to the transport unit 12 (transport plate 12a, etc.) Even if there is a difference in the level of the detection signal between the pixels 14a, it is possible to correct this difference and obtain an appropriate detection signal for each line. As a result, an appropriate correction coefficient is calculated using a detection signal acquired in a state where there is a gap X between the transport plates 12a between the X-ray irradiator 13 and the X-ray line sensor 14 that are specified thereafter. Thus, highly accurate calibration can be performed.

(3)
In the X-ray inspection apparatus 10 of the present embodiment, the control computer 20 detects the detection signals for a plurality of lines corresponding to one pitch or more of the transport plate 12a acquired by the X-ray line sensor 14 from the brighter side on the X-ray image. 10 lines are selected in order (from the detection signal with the higher detection level), and this average is calculated.

  Thereby, while being able to specify the detection signal acquired in the state with the clearance gap X between the conveyance plates 12a between the X-ray irradiator 13 and the X-ray line sensor 14, the average value can be calculated. Therefore, it is possible to appropriately calculate the correction coefficient used when performing calibration. As a result, highly accurate calibration can be performed using the correction coefficient calculated appropriately.

(4)
In the X-ray inspection apparatus 10 of the present embodiment, as shown in FIG. 7, the control computer 20 detects a detection signal detected in the X-ray irradiation state by the X-ray line sensor 14 as a detection signal serving as a calibration reference. In addition to (online detection signal), a detection signal at the time of non-irradiation of X-rays in a state where X-ray irradiation of the X-ray irradiator 13 is stopped is acquired.

Thus, when performing calibration, the correction coefficient is calculated based on the detection signal and the on-line detection signal when X-rays are not irradiated according to the relational expression (1) and the relational expression (2). Can be implemented.
(5)
In the X-ray inspection apparatus 10 of the present embodiment, the control computer 20 controls the transport unit 12 so as to transport at a transport speed set in a normal inspection even when performing calibration.

  Thereby, even in the X-ray inspection apparatus 10 that transports the product G to be inspected by using a plurality of transport plates 12a with a predetermined gap X in the transport direction, in order to perform calibration Automatic without troublesome control such as specially slowing down the transfer speed or stopping the transfer with the gap X between the transfer plate 12a between the X-ray irradiator 13 and the X-ray line sensor 14 It is possible to perform highly accurate calibration.

[Other Embodiments]
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention.
(A)
In the above-described embodiment, the detection signal detected in the plurality of pixels 14a included in the X-ray line sensor 14 arranged in the direction orthogonal to the transport direction has been described with an example in which an average value is taken. However, the present invention is not limited to this.

For example, a detection result in a specific pixel 14a arranged near the center of the X-ray line sensor 14 can be used as a detection signal in that line.
However, since the average value of the detection signal in each pixel 14a is calculated as in the above embodiment, for example, the X-ray line sensor 14 and the transport unit 12 (the transport plate 12a and the like) are not parallel to each other. Even when there is a difference between the pixels 14a in the same line of the detection signal, it is possible to suppress the variation in the detection signal in the direction orthogonal to the transport direction and perform high-precision calibration. it can.

(B)
In the above embodiment, the detection signals for the number of lines corresponding to one pitch or more are acquired, the average value of the detection signals for 10 lines is calculated in order from the brightest, and this is used as the reference value for calibration. I gave it as an explanation. However, the present invention is not limited to this.
For example, an average value of detection signals for 3 to 8 lines may be calculated in order from the brighter side, and this may be used as a calibration reference.

Even in this case, since the gap between the transport plates is usually larger than one line, the calibration reference is made by using the average value of the detection signals for a plurality of lines from the brighter side so as not to pass through the transport plate. By specifying the detection signal detected in step (1), highly accurate calibration can be performed.
(C)
In the embodiment described above, the control computer 20 uses the pixels 14a included in the X-ray line sensor 14 for each line for the detection signals for the number of lines corresponding to one or more pitches of the transport plate 12a acquired by the X-ray line sensor 14. The example of calculating the average value of the detection signals detected in the above has been described. However, the present invention is not limited to this.

For example, another statistical value indicating the magnitude of the signal for one line such as the minimum value of the detection signal included in one line may be used.
Even in this case, since the plate interval can be specified using the minimum value for one line, the same effect as described above can be obtained.
(D)
In the above embodiment, as shown in FIG. 6B, the gap X between the transport plates 12a is detected by the X-ray irradiator 13, the X-ray line sensor 14, and the detection signal serving as a reference for the correction coefficient for calibration. An example in which the signal is acquired based on the detection signal in a state on the line connecting the two has been described. However, the present invention is not limited to this.

For example, when the thickness of the transport plate 12a is constant, the transport plate 12a is on a line connecting the X-ray irradiator 13 and the X-ray line sensor 14 as shown in FIG. A detection signal may be acquired.
Even in this case, highly accurate calibration can be performed with reference to X-rays detected via the transport plate 12a.

However, as shown in FIG. 6B, if the detection signal is acquired in a state where nothing exists on the line connecting the X-ray irradiator 13 and the X-ray line sensor 14, the correction coefficient is reduced without variation. In terms of accurate calculation, it is more preferable to perform calibration as in the above embodiment.
(E)
In the above-described embodiment, in the case where the width of the transport plate is 150 mm and the gap between the transport plates is 15 mm, an example is described in which detection signals for the number of lines corresponding to 200 mm or more are acquired when performing calibration. However, the present invention is not limited to this.

  For example, when the width of the transport plate or the size of the gap X between the transport plates fluctuates, detection signals for the number of lines corresponding to more than the sum of the width of the transport plate and the gap X between them are generated. It is only necessary to acquire detection signals for an appropriate number of lines in accordance with that. In other words, by acquiring detection signals for the number of lines corresponding to a length equal to or greater than the sum of the width of the transport plate and the gap X between them, the detection signals are reliably acquired from among the detection signals through the transport plates. A detection signal can be obtained and specified.

Moreover, even if it is the same conditions as the said embodiment, it is not limited to 200 mm, What is necessary is just to acquire the detection signal for the number of lines larger than 165 mm.
(F)
In the said embodiment, the example which applied this invention with respect to the X-ray inspection apparatus was given and demonstrated. However, the present invention is not limited to this.

For example, the present invention may be applied to an X-ray inspection program stored in a storage unit of an X-ray inspection apparatus and causing a computer to execute the above-described X-ray inspection method.
Even in this case, the X-ray inspection program is read by the computer, so that highly accurate calibration can be performed using each component included in the X-ray inspection apparatus.

  The X-ray inspection apparatus of the present invention has the effect of being able to carry out highly accurate calibration without troublesome work and cost increase, so that X-rays are conveyed while being conveyed using a plate conveyor. The present invention can be widely applied to various inspection apparatuses that perform inspections by irradiating them.

1 is an external perspective view of an X-ray inspection apparatus according to an embodiment of the present invention. The top view which shows the structure of the inspection system containing the X-ray inspection apparatus of FIG. The simple block diagram inside the shield box of the X-ray inspection apparatus of FIG. The block block diagram of the control computer mounted in the X-ray inspection apparatus of FIG. The side view which shows typically the structure inside the shield box of the X-ray inspection apparatus of FIG. (A), (b) is a schematic diagram which shows the positional relationship of a conveyance plate at the time of implementing a calibration, an X-ray irradiator, and a line sensor. The flowchart which shows the flow of the calibration performed by the X-ray inspection program which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 X-ray inspection apparatus 11 Shield box 11a Carry-in entrance 11b Carry-out exit 12 Conveyor (conveyance part)
12a Conveying plate 12b Conveyor frame 12c Opening 12d Conveyor guide 12f Conveyor motor 12g Rotary encoder 13 X-ray irradiator (irradiation unit)
14 X-ray line sensor (light receiving part)
16 Shielding Nolen 20 Control computer (control unit)
21 CPU
22 ROM (storage unit)
23 RAM (storage unit)
24 USB (external connection terminal)
25 CF (Compact Flash (registered trademark), storage unit)
25a, 25b File 26 Monitor G Product X Clearance

Claims (6)

An X-ray inspection apparatus that inspects the article by irradiating the article to be conveyed with X-rays and detecting the X-ray transmitted through the article,
An irradiation unit for irradiating the article with X-rays;
A light receiving unit for detecting X-rays emitted from the irradiation unit;
The article is transported in a predetermined direction by moving a plurality of transport plates arranged in the transport direction with a predetermined gap in the transport direction of the article between the irradiation unit and the light receiving unit. A transport section;
While moving the transport plate in the transport direction, the detection signal in the light receiving unit is acquired for a plurality of lines corresponding to one pitch or more in the transport direction of the transport plate, and the light receiving unit is based on the detection signal for the plurality of lines A control unit for correcting the X-ray detection sensitivity in
X-ray inspection apparatus. The control unit calculates a statistical value representing the magnitude of a signal for one line in a direction orthogonal to the transport direction for each line for the detection signals for the plurality of lines acquired in the light receiving unit,
The X-ray inspection apparatus according to claim 1. The control unit calculates an average value for the plurality of lines.
The X-ray inspection apparatus according to claim 1 or 2. The control unit causes the light receiving unit to acquire an offline signal when X-ray irradiation in the irradiation unit and conveyance in the conveyance unit are in a stopped state.
The X-ray inspection apparatus according to any one of claims 1 to 3. When the control unit corrects the X-ray detection sensitivity in the light receiving unit, the control unit sets the conveyance speed in the conveyance unit to the same speed as in normal inspection.
The X-ray inspection apparatus according to any one of claims 1 to 4. An irradiation unit that irradiates the article with X-rays, a light receiving unit that detects X-rays emitted from the irradiation unit, and a predetermined gap in the conveyance direction of the article between the irradiation unit and the light receiving unit An X-ray inspection program for controlling an X-ray inspection apparatus comprising: a transport unit configured to transport the article in a predetermined direction by moving a plurality of transport plates arranged in an empty state in the transport direction. ,
A first step of acquiring detection signals for the plurality of lines corresponding to one pitch or more in the transport direction of the transport plate while moving the transport plate in the transport direction;
A second step of correcting the X-ray detection sensitivity in the light receiving unit based on the detection signal calculated for each line;
An X-ray inspection program for causing a computer to execute an X-ray inspection method comprising:

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