JP2011209177A - X-ray inspection device and method for operating the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray inspection device capable of normally performing determination of quality even undergoing an influence of aging.SOLUTION: The X-ray inspection device includes an X-ray generator, an X-ray detector, an X-ray transmission image forming part, and a quality determination part; wherein the quality determination part has a simulated degraded-image-quality level setting means, and the simulated degraded-image-quality level setting means sets a simulated degraded-image-quality level which is a desired level of a degraded image of a non-defective image of an X-ray transmission image determined to be good based on a determination standard in order to make the X-ray inspection device into a simulated degraded condition; the X-ray inspection device is made into the simulated degraded condition by controlling at least one of the X-ray generator, the X-ray detector, the X-ray transmission image forming part correspondingly to the set simulated degraded-image-quality level; and the X-ray inspection device under the simulated degraded condition includes an operation confirmation part for confirming the quality determination to be normal.

Description

  The present invention relates to an X-ray inspection apparatus including an X-ray generator and an X-ray detector, and more particularly to an X-ray inspection apparatus capable of operating normally in consideration of secular changes of the X-ray generator and X-ray detector, Relates to an operation method of the X-ray inspection apparatus.

  Conventionally, it detects fresh foods such as raw meat and fish, processed foods such as bread, products such as pharmaceuticals and industrial products, or foreign substances (metal, glass, plastic, stones, bones, etc.) mixed in packages that package the products. There is an X-ray inspection apparatus for inspecting product deformation (cracking or chipping) or inspecting product missing (number shortage). Such an X-ray inspection apparatus is installed in a production line, for example, and inspects a product (inspected object) conveyed by a conveying means such as a belt conveyor.

  The X-ray inspection apparatus performs image processing on an X-ray generator that irradiates the inspection object with X-rays, an X-ray detector that detects X-rays transmitted through the inspection object, and a density signal from the X-ray generator. An image processing apparatus that creates an X-ray transmission image and determines the quality of the inspection object from the image.

  In the X-ray generator, for example, a cylindrical X-ray tube provided inside a metal box is immersed in insulating oil, and an X-ray is irradiated by irradiating an anode target with an electron beam from the cathode of the X-ray tube. Is supposed to generate. The dose of the generated X-ray is adjusted by the tube current flowing through the X-ray tube.

  On the other hand, for the X-ray detector, for example, an arrayed line sensor including a plurality of photodiodes arranged in a line and a scintillator provided on the photodiode is used. The scintillator absorbs X-ray energy and converts it into light. The light converted by the scintillator is converted into an electric signal representing the concentration by the photodiode. This electric signal is A / D converted and sent to the image processing apparatus.

  In the image processing apparatus, an X-ray transmission image is created from a digital signal representing density, and the product is inspected by performing image processing on the X-ray transmission image.

  In general, the dose of X-rays generated by the X-ray detector and the sensitivity of the X-ray detector change with time (aging). For this reason, the image quality of the X-ray transmission image is lowered and the sensitivity of the X-ray inspection apparatus is lowered, that is, the inspection accuracy is lowered.

  Therefore, the X-ray inspection apparatus has a function of correcting the sensitivity, and the sensitivity is corrected at the time when the operation of the X-ray inspection apparatus is started (sensitivity correction). Such sensitivity correction is performed to eliminate the influence of the secular change of the X-ray generator and the X-ray detector on the inspection accuracy (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2001-4560

  However, if the sensitivity correction of the X-ray inspection apparatus is performed at the start of movement of the production line, for example, at the start of work, it is generally operated until the end of work with the operating conditions.

  In such an operation, when the inspection accuracy of the X-ray inspection apparatus is reduced due to the sensitivity correction, the sensitivity correction, and the influence of secular change during a short period of time, the X-ray inspection apparatus normally performs the pass / fail judgment. There is a risk that a defective product may be erroneously determined as a non-defective product.

  In order to prevent such a situation from occurring, it is conceivable to frequently perform sensitivity correction, but this is not efficient because the production line must be stopped each time. Further, it is conceivable to constantly monitor the dose of X-rays generated by the X-ray generator or the sensitivity of the X-ray detector. However, if such a function is provided, the configuration of the X-ray inspection apparatus becomes complicated. There is.

  Therefore, an object of the present invention is that an X-ray inspection apparatus operating under the operating condition after sensitivity correction erroneously determines a defective product as a non-defective product due to the influence of secular change that occurs during a short period until the next sensitivity correction. An object of the present invention is to provide an X-ray inspection apparatus capable of confirming that there is no problem.

  Another object of the present invention is to provide a method for operating such an X-ray inspection apparatus.

  The present invention has been made based on the following idea. That is, instead of directly monitoring the deterioration of the X-ray generator and the X-ray detector itself due to secular change, the image quality of the X-ray transmission image reflecting the deterioration of the X-ray generator and / or the X-ray detector itself. By monitoring this, the deterioration of the X-ray generator and / or the X-ray detector itself is indirectly recognized.

  When the X-ray generator and / or the X-ray detector changes with time and deteriorates, the image quality of the X-ray transmission image deteriorates. Therefore, if the deterioration of the image quality is detected, it can be predicted that the X-ray generator and / or the X-ray detector are deteriorated due to aging.

  Here, the deterioration in image quality refers to the degree of deterioration in image quality when the density distribution of the pixels of the image changes to a state that is more difficult to determine when determining the quality of the inspection object based on the X-ray transmission image.

  In the determination of the presence or absence of foreign matter, the variation in density in an image area free of foreign matter increases due to image quality deterioration, resulting in a rough image. Judged as non-defective). In addition, when the gradation difference (contrast) of the entire image disappears due to the deterioration of image quality and the gradation gradation is crushed, the difference in gradation between the image area with the foreign object and the image area without the foreign object is reduced, and the foreign object is detected. (A defective product is mistakenly determined to be a good product).

  If the inspection object is deformed or missing, if the image quality deteriorates, the boundary (edge) between the image area of the inspection object and the image area other than the inspection object will be blurred, or the difference in shading will be small and unclear. Thus, the image area of the inspection object cannot be correctly extracted.

  The degree of such image degradation, that is, the degree of image degradation is set in terms of density level difference or ratio.

  Therefore, if a situation in which the image quality of the image deteriorates is intentionally created in the X-ray inspection apparatus, a state equivalent to the state in which the X-ray inspection apparatus deteriorates due to aging of the X-ray generator and / or X-ray detector is simulated. Can be made. Hereinafter, such a state of the X-ray inspection apparatus is referred to as a simulated deterioration state.

  At the start of movement of the production line, sensitivity correction of the X-ray inspection apparatus is performed, and then the X-ray inspection apparatus is put into a simulated deterioration state. If it can be confirmed that the pass / fail judgment of the X-ray inspection apparatus is normally executed in this state, the pass / fail judgment is normally executed even in the simulated deterioration state. Therefore, the X-ray inspection apparatus is operated under the operating conditions after the sensitivity correction. However, it is guaranteed that the pass / fail judgment will be normally executed until the next sensitivity correction.

  When the X-ray inspection apparatus is put into a simulated deterioration state, it is important to what level the image quality is deteriorated. In the present invention, this target level is referred to as a simulated degraded image quality level.

  The simulated image quality level is changed from a state in which it is correctly determined to be a non-defective product based on a non-defective image that is a non-defective image to a state in which the image quality of the non-defective image is deteriorated and determined to be a defective product. Is the image quality level. That is, it is a level that is guaranteed to be reliably determined to be a non-defective product when a pass / fail determination is made based on a non-defective image whose image quality has deteriorated to the simulated deteriorated image quality level.

  Such a simulated degradation image quality level is defined as the image quality degradation degree C, which is the degree of image quality degradation from the image quality level (L0) of a non-defective image to the transition image quality level (L1) that transitions to a state that is determined to be defective. In this case, the image quality deterioration degree C is set to a level L2 that is returned from the level L0 to the deterioration side by a predetermined ratio, for example, (1/2 to 4/5) C. Therefore, a minimum (1/5) C level difference is ensured between the transition image quality level L1 and the simulated deteriorated image quality level L2. This level difference is called margin.

  In other words, the simulated degraded image quality level is set based on the margin. The reason for providing such a margin is that if the simulated degradation image quality level L2 is too close to the transition image quality level L1, that is, if the margin is too small, the pass / fail judgment is made when confirming the operation of the simulated degradation X-ray inspection apparatus. This is because it is not constant and the reliability of the pass / fail judgment cannot be confirmed.

  If the simulated degradation image quality level is determined in advance, the level determined in advance may be set, or may be obtained by calculation in the X-ray inspection apparatus.

  Then, it is confirmed whether or not the X-ray inspection apparatus in the simulated deterioration state normally executes the pass / fail determination. If it can be confirmed that the pass / fail judgment is normally executed, it is possible to perform a normal inspection under the operating conditions of the X-ray inspection apparatus at the start of operation of the production line.

  Therefore, the present invention provides an X-ray generator that generates X-rays to be irradiated on an object to be inspected, an X-ray detector that converts X-rays transmitted through the object to be inspected into an electrical signal, and an output from the X-ray detector. An X-ray comprising an X-ray transmission image forming unit that forms an X-ray transmission image based on an electrical signal, and a pass / fail determination unit that determines pass / fail of the inspection object based on the X-ray transmission image and a predetermined criterion. In the inspection apparatus, the quality determination unit includes a simulated degradation image quality level setting unit, and the simulated degradation image quality level setting unit is determined to be a non-defective product based on a determination criterion in order to put the X-ray inspection apparatus into a simulated degradation state. A simulated degradation image quality level that is a target level for degrading the image quality of a non-defective image that is an X-ray transmission image is set, and an X-ray generator, an X-ray detector, At least the X-ray transmission image forming part The X-ray inspection apparatus is controlled to be in a simulated deterioration state by controlling one, and the X-ray inspection apparatus in the simulated deterioration state further includes an operation confirmation unit for confirming whether the quality determination unit is normal. .

  The simulated degraded image quality level setting unit sets the simulated degraded image quality level so that the simulated degraded image quality level has a predetermined margin with respect to the image quality level L1.

  The X-ray generator, X-ray detector, and X-ray transmission image forming unit are controlled as follows.

  In the X-ray generator, the tube current of the X-ray generator is controlled so as to attenuate the X-ray output in accordance with the set simulated deterioration image quality level. When the tube current of the X-ray generator is controlled, the amount of X-ray irradiation decreases, and the amount of X-ray transmitted through the object to be inspected also decreases according to the amount of irradiation. Therefore, the electrical signal output from the X-ray detector Becomes smaller and the whole image becomes dark.

  The X-ray detector is controlled so as to reduce the gain of the X-ray detector in accordance with the set simulated deterioration image quality level. By setting the X-ray detector to a gain smaller than usual, the level of the electric signal with respect to the amount of X-rays transmitted through the object to be inspected is reduced, and the entire image becomes a dark image. The noise level superimposed on the electric signal in the circuit of the X-ray detector does not decrease even if the level of the electric signal to be output becomes small. Therefore, the ratio between the level of the electric signal corresponding to the amount of X-ray transmission and the noise level. The (S / N ratio) decreases and the X-ray transmission image becomes a rough image, and the image quality deteriorates.

  The X-ray transmission image forming unit controls the density difference (contrast) to be reduced by increasing or decreasing the density of the X-ray transmission image formed by the image forming unit in accordance with the set simulated deterioration image quality level. Specifically, the density of each pixel is nonlinearly transformed so that the shading is crushed, or a white noise image is overlaid to roughen the image quality. The density conversion formula or conversion table and the statistic (average value, variance value) of the white noise image are determined and stored in advance so as to correspond to the degree of image quality degradation.

  As described above, the operation confirmation unit inspects the inspection object with the X-ray inspection apparatus in a simulated deterioration state, and confirms that the X-ray inspection apparatus is normally performing the pass / fail determination.

  Further, the operation method of the X-ray inspection apparatus according to the present invention is based on a criterion for correcting the sensitivity of the X-ray transmission image forming unit at the start of the operation of the X-ray inspection apparatus and putting the X-ray inspection apparatus into a simulated deterioration state. A simulated degradation image quality level, which is a target level for degrading the image quality of a non-defective image that is determined to be a non-defective image based on the image quality, is set, and X-ray generation is performed in accordance with the set simulated degradation image quality level. The X-ray inspection apparatus is controlled to be in a simulated deterioration state by controlling at least one of the detector, the X-ray detector, and the X-ray transmission image forming section. If it is confirmed that the normality is good and the good / bad determination of the good / bad determination unit is normal, the inspection of the inspection object is started under the operation condition after the sensitivity correction.

  According to the present invention, even if the X-ray inspection apparatus operating under the operating condition after the sensitivity correction is affected by the secular change that occurs during the short period until the next sensitivity correction, the X-ray inspection apparatus is put into a simulated deterioration state. Since it has been confirmed that the X-ray inspection apparatus normally performs the pass / fail determination in the simulated deterioration state, the defective product is not erroneously determined as a non-defective product.

It is a figure which shows the basic composition of one Embodiment of the X-ray inspection apparatus of this invention. It is a functional block diagram of the image processing apparatus of FIG. It is a figure for demonstrating the concept of the simulation degradation image quality level. It is a figure for demonstrating pass / fail determination. It is a flowchart explaining the operation | movement in the case of setting the simulation degradation image quality level determined beforehand. It is a figure which shows the setting of the simulation degradation image quality level. It is a flowchart explaining the operation | movement in the case of setting the calculated simulation degradation image quality level.

  Embodiments of the X-ray inspection apparatus according to the present invention will be described below.

(Basic configuration of X-ray inspection equipment)
As shown in FIG. 1, the X-ray inspection apparatus includes an X-ray generator 10, an X-ray detector 12, and an image processing device 14. The X-ray generator 10 is arranged above the belt conveyor 18 that conveys the product 16 to be inspected in the production line, and the X-ray detector 12 is below the belt conveyor 18, and the X-ray generator 10 is arranged at a position corresponding to 10.

  The X-ray generator 10 is the same as that described in the background art. The X-ray tube built in the X-ray generator 10 is provided in the width direction (Y direction) whose longitudinal direction is orthogonal to the product conveyance direction (X direction). The X-rays 20 generated by the X-ray tube are irradiated toward the lower X-ray detector 12 in the form of a substantially triangular screen in the direction orthogonal to the transport direction by the slit.

  The X-ray detector 12 is the same as that described in the background art, receives X-rays that have been irradiated and transmitted through the product 16, and outputs an electrical signal representing the concentration. The electric signal is converted into a digital density signal by an A / D converter. In the case of 8 bits, this digital density signal displays a density of 256 gradations. Although not shown, the A / D converter is built in the X-ray detector 12.

  The image processing apparatus 14 basically has a function of forming an X-ray transmission image from the digital density signal and performing image processing on the X-ray transmission image to determine whether the image is a non-defective product or a defective product. .

  Judgment criteria for pass / fail determination are selected according to the content of inspection, for example, inspection for the presence or absence of foreign matter, inspection of product deformation (cracking or chipping), inspection of product missing (insufficient number), and the like.

  In the case of the presence or absence of foreign matter, it is a threshold value for the pixel density after image processing (eg, exaggerating the foreign matter and smoothing out the foreign matter), and in the case of product deformation or missing, image processing (inspected) This is a threshold value for the number of areas, the peripheral length, the number of pixels, etc. of a predetermined area after emphasizing the edge of the object and binarizing.

(Configuration of Image Processing Device 14)
As shown in FIG. 2, the image processing apparatus 14 includes a personal computer having an input unit 22, an output unit 24, and an image processing unit 26.

  The input unit 22 inputs an instruction to the image processing unit 26, and is configured by a keyboard, for example.

  The output unit 24 displays the output of the image processing unit 26 and includes a display and a printer.

  The image processing unit 26 is a central processing unit of a personal computer, and executes various processes using software. Functionally, as shown in FIG. 2, it includes an X-ray transmission image forming unit 28, a pass / fail determination unit 30, a switching unit 32, and an operation confirmation unit 34.

  The X-ray transmission image forming unit 28 forms an X-ray transmission image based on the density signal from the X-ray detector 12. The X-ray transmission image is composed of, for example, 480 lines (X direction) and 640 pixels on one line. Therefore, the X-ray transmission image is composed of 640 × 480 pixels. The density of one pixel is expressed by the light and shade of 256 gradations (0: white, 255: black). The X-ray transmission image forming unit 28 is configured so that the sensitivity is corrected and an X-ray transmission image can be formed with the best sensitivity.

  The pass / fail determination unit 30 performs image processing on the X-ray transmission image and determines pass / fail of the inspection object based on the determination criterion. Judgment criteria for pass / fail determination are selected according to the content of inspection, for example, inspection for the presence or absence of foreign matter, inspection of product deformation (cracking or chipping), inspection of product missing (insufficient number), and the like.

  In the case of the presence or absence of foreign matter, it is a threshold value for the pixel density after image processing (eg, exaggerating the foreign matter and smoothing out the foreign matter), and in the case of product deformation or missing, image processing (inspected) This is a threshold value for the number of areas, the peripheral length, the number of pixels, etc. of a predetermined area after emphasizing the edge of the object and binarizing.

  Such a quality determination unit 30 includes a simulated deterioration image quality level setting unit 36. The simulated degraded image quality level setting unit 36 sets a simulated degraded image quality level.

  The concept of the simulated deterioration image quality level will be described in detail below. FIG. 3 is a diagram for explaining deterioration of the image quality of a non-defective image collected from non-defective products. The vertical axis represents the degree of image quality degradation, and the horizontal axis is the time axis.

  The image quality level of the non-defective image collected from the non-defective product is L0. Under the control of the X-ray generator 10, the X-ray detector 12, or the X-ray transmission image forming unit 28, the image quality is gradually deteriorated. A quality determination is performed on such a deteriorated image.

  As shown in FIG. 4, the pass / fail judgment is performed according to a selected judgment criterion (threshold value). For example, in the case of foreign matter inspection, a threshold value for pixel density is selected. When the pixel density becomes dark and exceeds the threshold value, it is determined that the product is defective with foreign matter.

  The level of the deteriorated image in FIG. 3 at the time when it is determined as a defective product is referred to as a transition image quality level, assuming that the non-defective image has transitioned to a defective product image. The transition image quality level is L1.

  The simulated deteriorated image quality level is set to a level before reaching the transition image quality level L1. In the figure, the simulated degraded image quality level is indicated by L2. Specifically, when the difference between the image quality level L0 and the transition image quality level L1 of the non-defective image is an image quality degradation degree C as shown in the figure, the image quality is degraded by (1/2 to 4/5) C from the level L0. The level returned to the side is set to the simulated deteriorated image quality level L2. This simulated deteriorated image quality level L2 is set with an allowance for the transition image quality level L1. That is, the simulated degradation image quality level L2 has a margin of at least (1/5) C with respect to the transition image quality level L1.

The simulated degradation image quality level setting means 36 sets such a simulated degradation image quality level. There are the following two methods.
(1) The simulated degraded image quality level setting means 36 receives a predetermined simulated degraded image quality level and sets the input simulated degraded image quality level.
(2) The simulated degraded image quality level setting unit 36 calculates the simulated degraded image quality level and sets the calculated simulated degraded image quality level.

  The simulated degraded image quality level set by any method is sent to the operation check unit 38.

  The switching unit 32 switches connection of the pass / fail determination unit 30 to either the operation confirmation unit 34 or the output unit 24 according to an instruction from the input unit 22.

  The operation confirmation unit 34 controls at least one of the X-ray generator 10, the X-ray detector 12, and the X-ray transmission image forming unit 28 to put the X-ray inspection apparatus in a simulated deterioration state. The X-ray generator 10 is controlled to decrease the X-ray irradiation intensity, the X-ray detector 12 is controlled to decrease the signal level of the electrical signal, or the X-ray transmission image forming unit 28 is controlled. Thus, the density of each pixel of the X-ray transmission image is increased or decreased.

  The product is inspected with the simulated X-ray inspection apparatus, and the operation confirmation unit 34 confirms the normal operation of the X-ray inspection apparatus. The result of the operation check is sent to the output unit and displayed.

(Operation of X-ray inspection equipment)
The operation of the X-ray inspection apparatus will be described with reference to a flowchart. In the following explanation,
-When the simulated deterioration image quality level setting means sets a predetermined simulated deterioration image quality level;
The case where the simulated degraded image quality level setting unit 36 calculates the simulated degraded image quality level and sets the calculated simulated degraded image quality level will be described separately.

First, the operation when the simulated degradation image quality level setting unit 36 sets a predetermined simulated degradation image quality level will be described with reference to the flowchart of FIG.
・ Sensitivity correction mode (step S1)
At the start of movement of the production line, the input unit 22 instructs the image processing unit 26 to perform sensitivity correction. The X-ray transmission image forming unit 28 corrects the sensitivity so that the X-ray inspection apparatus operates at the best sensitivity. There are various sensitivity correction methods. For example, with an X-ray inspection apparatus before sensitivity correction, the image density at the time of X-ray irradiation and the image density at the time of non-X-ray irradiation are sampled, and a correction coefficient is obtained from these densities. Thus, the actual image density at the time of product inspection is converted (see Japanese Patent Laid-Open No. 2001-4560).

-Simulated deterioration image quality level setting mode (step S2)
The input unit 22 instructs the simulated degraded image quality level setting unit 36 to set the simulated degraded image quality level. At the same time, the switching unit 32 is switched to the output unit 24 side according to an instruction from the input unit 22.

  Prior to setting the simulated deterioration image quality level, a non-defective image is collected by the sensitivity-corrected X-ray inspection apparatus (step S21). The quality image is determined by the quality determination unit 30, and the determination result is displayed on the output unit 24 to confirm that it is a quality product (step S22).

  If it is confirmed that the product is a non-defective product, the simulated degradation image quality level setting unit 36 acquires the image quality level L0 of the good product image (step S23).

  A predetermined simulated degradation image quality level L2 is input from the input unit 22 to the simulated degradation image quality level setting unit 36 of the pass / fail determination unit 30. The simulated degradation image quality level setting means 36 sets a predetermined simulated degradation image quality level L2 based on the image quality level L0 of the non-defective image (step S24). In the case of this example, as shown in FIG. 6, the simulated deteriorated image quality level is set to a level L2 that is returned to the deteriorated side by (1/2) C from the image quality level L0 of the non-defective image. In this case, the image quality deterioration degree C is assumed to be known in advance.

At the same time, the switching unit 32 is switched to the operation confirmation unit 34 side according to an instruction from the input unit 22. The simulated deteriorated image quality level L2 is sent to the operation check unit 34.
・ Operation check mode (step S3)
The input unit 22 instructs the image processing unit 26 to confirm the operation. Thereby, the switching part 32 is switched to the operation confirmation part 34 side.

  The operation confirmation unit 34 controls at least one of the X-ray generator 10, the X-ray detector 12, and the X-ray transmission image forming unit 28 so as to degrade the image quality. In this example, it is assumed that the X-ray generator 10 is controlled.

  The operation confirmation unit 38 controls the tube current of the X-ray generator 10 so as to attenuate the X-ray output in accordance with the set simulated deterioration image quality level. When the tube current of the X-ray generator 10 is controlled, the amount of X-ray irradiation decreases, and the amount of X-ray transmitted through the object to be inspected decreases according to the amount of irradiation. The signal also becomes small, the whole image becomes dark, and the image quality deteriorates. As a result, the X-ray inspection apparatus is placed in a simulated deterioration state.

  Next, the X-ray inspection apparatus in such a simulated deterioration state is operated to inspect the product, and the pass / fail determination unit 30 performs pass / fail determination to confirm that the pass / fail determination is executed normally.

  In the pass / fail judgment, an X-ray transmission image is judged pass / fail using a product known to be a non-defective product, and it can be confirmed that the pass / fail judgment is normal when the product is good. As a matter of course, a product that is known to be defective may be used, and both good product determination and defective product determination may be confirmed. It may be displayed on the screen of the output unit 24 which one of products that are known to be non-defective products and products that are known to be defective products, and in which order is used.

  The operation confirmation result of the operation confirmation unit 38 is sent to the output unit 24 and displayed.

Normal operation mode (Step S4)
If it can be confirmed that the quality determination of the X-ray inspection apparatus is normally executed in the operation confirmation mode, the normal operation mode is instructed from the input unit 22, and the switching unit 32 is switched to the output unit 24 side.

  The production line is in operation, and the X-ray inspection equipment sequentially inspects the products conveyed by the belt conveyor under the operating conditions after sensitivity correction performed at the start of operation of the production line, and determines whether the product is good or defective. It is.

  In the normal operation mode, even if there is a secular change in the X-ray generator and / or the X-ray detector during the period until the next sensitivity correction is made, even if the accuracy of the X-ray inspection apparatus is reduced, it is normal. Operation can be guaranteed.

  Next, the operation when the simulated deterioration image quality level setting unit 36 calculates the simulated deterioration image quality level and sets the calculated simulated deterioration image quality level will be described with reference to the flowchart of FIG. The flowchart in FIG. 7 is different from the flowchart in FIG. 5 only in the simulated degradation image quality level setting mode (step S2), and therefore only the simulated degradation image quality level setting mode will be described.

-Simulated deterioration image quality level setting mode (step S2)
The input unit 22 instructs the simulated degraded image quality level setting unit 36 to calculate the simulated degraded image quality level. At the same time, the switching unit 32 is switched to the output unit 24 side according to an instruction from the input unit 22.

  Prior to the calculation of the simulated degradation image quality level, a non-defective image is collected by the sensitivity-corrected X-ray inspection apparatus (step S21). The quality image is determined by the quality determination unit 30, and the determination result is displayed on the output unit 24 to confirm that it is a quality product (step S22).

  If it is confirmed that the product is a non-defective product, the simulated degradation image quality level setting unit 36 acquires the image quality level L0 of the good product image (step S23).

  Subsequently, the simulated degradation image quality level setting means 30 controls at least one of the X-ray generator 10, the X-ray detector 12, and the X-ray transmission image forming unit 28 in the same manner as in the above-described operation confirmation mode. In the example, the tube current of the X-ray generator 10 is decreased, the non-defective image is darkened, and the image quality is gradually deteriorated (step S24).

  At this time, the quality determination unit 30 performs quality determination based on the image that deteriorates (step S25). The image quality level at which the determination is defective is taken in as a transition image quality level L1 (step S26).

  The image quality degradation degree C which is the difference between the level L0 and the level L1 is calculated (step S27), and the margin is estimated, and only (1/2 to 4/5) C from the level L0, for example, (1/2) C. The level returned to the degraded side is set to the simulated degraded image quality level L2 (step S28).

  The following operations are the same as the operation confirmation mode (step S3) and the normal operation mode (step S4) described above.

  The present invention can be an X-ray inspection apparatus that detects foreign matters mixed in a product, inspects deformation (cracking or chipping) of a product, or inspects product missing (number shortage). Such an X-ray inspection apparatus is installed in a production line, for example, and can inspect a product conveyed by a conveying means such as a belt conveyor.

DESCRIPTION OF SYMBOLS 10 X-ray generator 12 X-ray detector 14 Image processing apparatus 22 Input part 24 Output part 26 Image processing part 28 X-ray transmissive image formation part 30 Pass / fail judgment part 32 Switching part 34 Operation | movement confirmation part 36 Simulated degradation image quality level setting means ( Setting method)

Claims (13)

An X-ray generator for generating X-rays to irradiate the inspection object;
An X-ray detector for converting X-rays transmitted through the inspection object into electrical signals;
An X-ray transmission image forming unit that forms an X-ray transmission image based on an electrical signal output from the X-ray detector;
In an X-ray inspection apparatus comprising: a pass / fail determination unit that determines pass / fail of the inspection object based on the X-ray transmission image and a predetermined criterion.
The pass / fail determination unit includes a simulated degradation image quality level setting unit, and the simulated degradation image quality level setting unit is determined to be a non-defective product based on the determination criterion in order to put the X-ray inspection apparatus into a simulated degradation state. Setting a simulated degradation image quality level that is a target level for degrading the image quality of a non-defective image that is such an X-ray transmission image,
The at least one of the X-ray generator, the X-ray detector, and the X-ray transmission image forming unit is controlled to correspond to the set simulated deterioration image quality level, and the X-ray inspection apparatus is in a simulated deterioration state. In the X-ray inspection apparatus in the simulated deterioration state, the X-ray inspection apparatus further includes an operation confirmation unit for confirming whether the quality determination unit is normal.   The simulated deterioration image quality level setting means determines the image quality level L0 of the non-defective image and the image quality determined to have transitioned from a non-defective product to a defective product based on the determination criterion when the image quality of the non-defective image is deteriorated. 2. The X-ray according to claim 1, wherein the level L 1 is acquired, and the simulated degradation image quality level is set based on an image quality degradation level that is a difference between the image quality level L 0 and the image quality level L 1. Inspection device.   3. The simulated degraded image quality level setting unit sets the simulated degraded image quality level so that the simulated degraded image quality level has a predetermined margin with respect to the image quality level L1. The X-ray inspection apparatus described.   The X-ray inspection apparatus according to claim 3, wherein the simulated degradation image quality level setting unit receives the simulated degradation image quality level determined in advance and sets the input simulated degradation image quality level.   The X-ray inspection apparatus according to claim 3, wherein the simulated deterioration image quality level setting unit calculates the simulated deterioration image quality level and sets the calculated simulated deterioration image quality level.   The said operation confirmation part controls the said X-ray generator, and reduces the image quality of the said non-defective image to the said simulated degradation image quality level by weakening the irradiation intensity | strength of X-ray | X_line. The X-ray inspection apparatus according to any one of 5.   2. The operation confirmation unit controls the X-ray detector to weaken the signal level of the electrical signal, thereby degrading the quality of the non-defective image to the simulated degradation image quality level. X-ray inspection apparatus in any one of -6.   The X-ray inspection according to claim 1, wherein the operation confirmation unit controls the X-ray transmission image forming unit to increase or decrease the density of each pixel of the X-ray transmission image. apparatus. The X-ray transmission image forming unit has a sensitivity correction function,
The X-ray transmission image forming unit forms the X-ray transmission image whose sensitivity is corrected,
The X-ray inspection apparatus according to claim 1, wherein the simulated deterioration image quality level setting unit sets a simulated deterioration image quality level based on the quality-corrected non-defective image. An X-ray generator for generating X-rays to irradiate the inspection object;
An X-ray detector for converting X-rays transmitted through the inspection object into electrical signals;
An X-ray transmission image forming unit that forms an X-ray transmission image based on an electrical signal output from the X-ray detector;
In an operation method of an X-ray inspection apparatus comprising: a pass / fail determination unit that determines pass / fail of the inspection object based on the X-ray transmission image and a predetermined criterion.
At the start of operation of the X-ray inspection apparatus, sensitivity correction of the X-ray transmission image forming unit is performed,
In order to put the X-ray inspection apparatus in a simulated deterioration state, a simulated deterioration image quality level that is a target level for degrading the image quality of a non-defective image that is an X-ray transmission image that is determined to be non-defective based on the determination criterion is set. And
The at least one of the X-ray generator, the X-ray detector, and the X-ray transmission image forming unit is controlled to correspond to the set simulated deterioration image quality level, and the X-ray inspection apparatus is in a simulated deterioration state. In the X-ray inspection apparatus in the simulated deterioration state, confirm that the pass / fail judgment of the pass / fail judgment unit is normal,
An X-ray inspection apparatus operating method, comprising: inspecting an inspection object under an operation condition after sensitivity correction when it is confirmed that the quality determination by the quality determination unit is normal.   The image quality of the non-defective image is degraded to the simulated degradation image quality level by controlling the X-ray generator and reducing the X-ray irradiation intensity at the time of the operation check. Method of X-ray inspection apparatus.   11. The image quality of the non-defective image is degraded to the simulated degradation image quality level by controlling the X-ray detector and weakening the signal level of the electrical signal when the operation is confirmed. The X-ray inspection apparatus according to 11.   The X-ray inspection apparatus according to claim 10, wherein the X-ray transmission image forming unit is controlled to increase or decrease the density of each pixel of the X-ray transmission image when the operation is confirmed.

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