JP2013190361A - X-ray inspection device and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a stable inspection even when luminance of an X-ray source is deteriorated in an X-ray inspection device.SOLUTION: An X-ray inspection device 1 includes: an X-ray source 10 which irradiates an inspection object with X-rays; determination means for determining whether or not the X-ray source 10 is deteriorated based on luminance of the X-rays irradiated from the X-ray source 10 and detected by an X-ray detector 30; and photographing condition control means for changing photographing conditions in an X-ray inspection of the inspection object when the luminance of the X-ray source 10 is lower than a threshold. It is preferable that the photographing conditions to be changed include at least any of photographing distance, the number of photographed pictures per inspection, exposure time, tube current of the X-ray source, and tube voltage of the X-ray source.

Description

  The present invention relates to an X-ray inspection apparatus and a control method thereof.

  Conventionally, the quality of an inspection target product is determined by irradiating the inspection target product with X-rays and analyzing the obtained transmission image (see, for example, Patent Document 1). Such an X-ray inspection apparatus is used, for example, for inspecting the soldering state of a mounted component soldered to a printed board, the quality of a wiring pattern on the board, and the like.

  The luminance of the X-ray source in the X-ray inspection apparatus deteriorates as the usage time elapses. When the X-ray luminance is deteriorated, the SN ratio is lowered, and the contrast between the inspection object and the other is deteriorated. If the X-ray luminance deterioration proceeds beyond a certain level, it becomes impossible to separate the inspection object from the other areas, and stable inspection becomes impossible.

JP 2006-162335 A

  In the conventional X-ray inspection apparatus, when the luminance deterioration of the X-ray source proceeds more than a certain level, the X-ray source is replaced. In other words, the X-ray source must be replaced even though no failure other than luminance degradation has occurred. Since the X-ray source is expensive, there is a problem that the maintenance cost becomes high.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique that enables stable inspection even when the luminance of an X-ray source is deteriorated.

  In order to achieve the above object, in the present invention, the brightness of the X-ray source is measured, and when the brightness of the X-ray source is lowered, the imaging conditions in the X-ray imaging are changed to improve the contrast and to stabilize the X-ray. Enable line inspection.

  More specifically, the present invention relates to an X-ray source that irradiates an inspection object with X-rays, an X-ray detector that detects X-rays, and an X-ray source that is irradiated from the X-ray source and detected by the X-ray detector. Determination means for determining whether or not the X-ray source has deteriorated based on the brightness of the X-ray, and imaging conditions in the X-ray inspection of the inspection object when it is determined that the X-ray source has deteriorated Photographing condition control means for changing

  The determination of the luminance deterioration of the X-ray source by the determination unit can be realized by several methods. The first method is a method of determining the luminance deterioration of the X-ray source based on the X-ray imaging result at the time of product shipment and the X-ray imaging result at the time of determination.

As an example, when the X-ray source emits X-rays without placing the inspection object, and the luminance value detected by the X-ray detector is lower than the detection value at the time of product shipment, the luminance is reduced. Judged as degraded. Alternatively, from two luminance values, that is, a luminance value detected by irradiating an X-ray from an X-ray source and a luminance value detected without irradiating the X-ray from the X-ray source without placing an inspection object. When the required gain (ratio between the output intensity and the detected luminance value) decreases by a certain level or more, it may be determined that the luminance has deteriorated. Further, the gain may be obtained from two or more measured values. By performing the luminance degradation determination based on the gain, it is possible to eliminate the influence of the degradation of the X-ray detector and to perform a more accurate determination. The threshold value for determining that the luminance has deteriorated can be an arbitrary value as long as the value is such that stable X-ray inspection cannot be performed when the luminance value becomes lower than the threshold value. Such a value can be obtained in advance by experiments or the like. In addition, when the X-ray inspection apparatus inspects a plurality of types of inspection objects, one threshold value that can stably inspect all the inspection objects may be stored, and for each inspection object A threshold value may be stored in.

  The second method for determining the luminance deterioration is a method for determining the luminance deterioration of the X-ray source based only on the X-ray imaging result at the time of determination. In this method, X-ray imaging is performed by placing an inspection object or a determination sample included in a predetermined determination pattern at an inspection target position. The determination pattern preferably includes a member to be distinguished in an actual inspection with a structure similar to that of the actual inspection object. As an example, the determination pattern is a pattern in which solder, a wiring pattern, and air are arranged. In the deterioration determination, if the luminance values detected by irradiating X-rays are different in each determination pattern, it is determined that there is no luminance deterioration, and the luminance value ranges for different determination patterns overlap. Is determined to have undergone luminance degradation. Even in this way, it is possible to determine the deterioration of the X-ray source. Note that the deterioration of the X-ray source may be determined by combining the first method and the second method.

  Examples of imaging conditions changed by the imaging condition control means include imaging distance, number of images to be captured, exposure time, X-ray source tube current, and X-ray source tube voltage. It should be noted that all of these shooting conditions may be changed, or only some of the shooting conditions may be changed.

  The imaging distance is a distance between the X-ray source and the X-ray detector. If the distance between the X-ray source and the X-ray detector is reduced, the intensity of X-rays irradiated on the unit area of the X-ray detector increases. Therefore, high-contrast X-ray imaging is possible. In order to change the imaging distance, means for changing the distance between the X-ray source and the inspection object is necessary. As long as this means can move the X-ray source and the X-ray detector relatively, the X-ray source may be moved or the X-ray detector may be moved. Further, both of these may be moved. When the distance between the X-ray source and the X-ray detector is changed, it is preferable to change the distance between the X-ray source and the inspection object so that the magnification in X-ray imaging does not change. Under the condition that the imaging magnification in X-ray imaging is not changed, the maximum value of the imaging distance allowed to be changed (shortened) is defined by the distance between the X-ray source and the inspection object.

  When performing X-ray imaging a plurality of times in one X-ray examination, it is also preferable to change the number of radiographs per examination. When inspection is performed based on the results of multiple X-ray imaging, the contrast is improved as the number of imaging is increased. Note that there is a demerit that the inspection time becomes longer when the number of shots is increased. The number of shots is preferably determined by comparison with an allowable inspection time.

  Contrast can also be improved by increasing the exposure time in X-ray imaging. Increasing the exposure time can typically be done by extending the exposure time of the camera. The pulse imaging method can also be performed by increasing the pulse width. When the exposure time of the camera is increased, there is a demerit that the inspection time becomes longer. Therefore, it is preferable to determine the exposure time compared to the allowable inspection time. Note that the contrast can be improved by performing imaging a plurality of times with the positions of the X-ray source, inspection object, and X-ray detector fixed, and adding the images.

The contrast in the X-ray inspection can also be improved by improving the tube current or tube voltage of the X-ray source. The X-ray irradiation intensity is proportional to the tube current and proportional to the square of the tube voltage. Therefore, the contrast is improved by increasing the tube current or the tube voltage. The adjustment limits of tube current and tube voltage are defined by the type of X-ray source.

  It is also preferable that the shooting condition control means not only change one shooting condition but also change a plurality of shooting conditions. In this case, it is preferable that after changing one imaging condition, the luminance of the X-rays emitted from the X-ray source is detected again by the X-ray detector, and the luminance deterioration determination is performed based on the detection result. If it is determined that the X-ray source has deteriorated even if one imaging condition is changed, it is preferable to change another imaging condition.

  If the imaging conditions to be changed are the imaging distance, the number of images to be taken, the exposure time, the tube current of the X-ray source, and the tube voltage of the X-ray source, for example, the conditions may be changed in this order. . That is, first, the shooting distance is adjusted, and the number of shots is increased when a sufficient luminance value cannot be obtained even when the shooting distance is closest within the allowable range. If a sufficient luminance value is not obtained even when the number of shots is increased, the exposure time may be changed. It should be noted that the order of the changes listed here is advantageous in that it follows less demerits, but it is not always necessary to use this order. In addition, after changing the first shooting condition, the second shooting condition may be changed, and then the first shooting condition may be changed again.

  With respect to each photographing condition, the adjustment amount (adjustment limit value) can be determined by various methods. For example, the tube current and tube voltage of the X-ray source can be determined by the performance of the X-ray source. Adjustment amounts can be set for the shooting distance, the number of shots, the exposure time, and the like according to input from the user. In addition, regarding the imaging distance, the distance between the X-ray source and the inspection object may be measured, and the distance (multiplied by a safety factor) may be used as the adjustment amount. When the X-ray inspection apparatus is used in the production line, the allowable inspection time is determined by the cycle time, so the adjustment amount may be determined based on the cycle time.

  The present invention can be understood as an X-ray inspection apparatus having at least a part of the above means. It can also be understood as a control method of the X-ray inspection apparatus including at least a part of the above processing or a program for realizing the method. Each of the above means and processes can be combined with each other as much as possible to constitute the present invention.

  According to the present invention, stable inspection can be performed even when the luminance of the X-ray source is deteriorated.

1 is a schematic block diagram of an X-ray inspection apparatus. The figure explaining the brightness | luminance degradation of an X-ray source, and the stability of a X-ray inspection. The flowchart which shows the flow of the lifetime determination of an X-ray source and the imaging condition change process in an X-ray inspection apparatus. The figure explaining the imaging condition of change object, the determination factor of the adjustment limit, and the setting method. The figure explaining the change of an imaging distance.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The X-ray inspection apparatus according to the present embodiment is an apparatus that determines the soldering state of a mounted component soldered to a printed board, the quality of a wiring pattern on the board, and the like. The X-ray inspection apparatus according to the present embodiment performs X-ray imaging a plurality of times by relatively moving the X-ray source and the inspection object (workpiece), and analyzes the three-dimensional structure of the workpiece.

<Device configuration>
FIG. 1 is a schematic block diagram of an X-ray inspection apparatus 1 according to the present embodiment. The X-ray inspection apparatus 1 generally includes an X-ray source 10, a source Z stage 11, a transfer device 21, a substrate XY stage 22, an X-ray detector 30, a camera XYZ stage 31, and a displacement meter 32. Each unit is controlled based on a control signal from the calculation unit 111. The X-ray inspection apparatus 1 includes a camera XYZ stage control unit 101, an X-ray image imaging unit 102, a height measurement unit 103, an inspection target position control unit 104, an X-ray source control unit 105, and an imaging height control as a control system. Part 106 is provided. Furthermore, the X-ray inspection apparatus 1 includes a calculation unit 111, a main storage unit 112, an auxiliary storage unit 113, an input unit 114, and an output unit 115.

  The X-ray source 10 irradiates the inspection target 20 with X-rays according to a command from the calculation unit 111 via the X-ray source control unit 105. The position of the X-ray source 10 can be adjusted by a Z-stage 11 for a source. Thereby, the relative distance between the X-ray source 10 and the inspection object 20 and the X-ray detector 30 can be controlled. The radiation source Z stage 11 is controlled by the imaging height control unit 106.

  Here, the inspection object 20 is a printed circuit board on which a mounting component is soldered. The inspection object 20 is transported by the transport device 21 and disposed between the X-ray source 10 and the X-ray detector 30 which are inspection positions. The inspection object 20 can be changed in position in the horizontal direction by the substrate XY stage 22 so that X-ray imaging can be performed from different directions. The inspection target unit 20 is transported to the inspection target position by the transport device 21, and the inspection position is adjusted by the substrate XY stage 22. The transfer device 21 and the substrate XY stage 22 are controlled by the inspection target position control unit 104.

The X-ray detector 30 is a two-dimensional X-ray detector that detects X-rays output from the X-ray source 10 and transmitted through the inspection object 20. The X-ray detector 30 is controlled by the X-ray image capturing unit 102. Further, as the X-ray detector 30, I.I. I. An (Image Intensifier) tube or an FPD (Flat Panel Detector) can be used. Although only one X-ray detector 30 is employed here, a plurality of X-ray detectors 30 may be used. The X-ray detector 30 can change the horizontal position and the vertical position by the camera XYZ stage 31. The camera XYZ stage 31 is controlled by the camera XYZ stage control unit 101.

  The displacement meter 32 measures the distance to the substrate. Therefore, it is possible to measure the warpage of the substrate that is the inspection object by the displacement meter 32. The substrate may be warped during the manufacturing process of the substrate, and the amount of warpage varies depending on the individual. Therefore, the warpage of each substrate is measured, and the height positions of the X-ray source 10 and the X-ray detector 30 are adjusted so that appropriate X-ray imaging can be performed.

With the above configuration, the X-ray inspection apparatus can operate the substrate and the X-ray detector 30 so that the substrate can be imaged from various directions. In the present embodiment, three-dimensional data of the inspection object 20 is generated using a three-dimensional data generation technique called CT (Computed Tomography) based on the imaging results from various directions as described above.

  Further, the X-ray inspection apparatus 1 can change the distance between the radiation source and the substrate and the distance ratio (magnification ratio) between the radiation source and the X-ray detector. That is, the X-ray inspection apparatus 1 can change the size or resolution of the inspection object 20 imaged by the X-ray detector 30.

  Although not shown, the X-ray inspection apparatus 1 also includes a camera that captures a visible image. The appearance of the substrate can be visually recognized by the visible image. The visible image is also used for acquiring an identifier such as a barcode or a two-dimensional code written on the substrate surface and grasping the type of the inspection object 20.

  As the computing unit 111, a general general-purpose computing device called a CPU (Central Processing Unit) or MPU (Microprocessor) can be used. A memory such as a RAM can be used as the main storage unit 112. As the auxiliary storage unit 113, a ROM, an HDD, or the like can be used. The input unit 114 is an arbitrary device such as a keyboard, a button, a switch, or a mouse that allows the user to input an instruction to the calculation unit 111. The output unit 115 is an arbitrary device such as a display or a speaker that can output the output from the calculation unit 111 by video or audio. That is, these functional units can be realized using a general computer system.

  When the calculation unit 111 reads and executes the program stored in the auxiliary storage unit 113, the life determination unit 201, the shooting condition control unit 202, the brightness threshold holding unit 203, the shooting condition holding unit 204, and the user input unit holding unit 205. Various functional units such as are realized.

<Luminance degradation>
Here, the luminance deterioration of the X-ray source 10 will be described. The brightness of the X-ray source 10 decreases with use time. FIG. 2 (a) shows this relationship. In the X-ray image, the components constituting the inspection object are identified according to the intensity (luminance) of the X-ray that passes through the inspection object and is detected by the X-ray detector. For example, if it is a printed circuit board, solder, a wiring pattern, air, etc. can be judged according to the X-ray dose detected by the X-ray detector 30.

  Even when the same member is measured due to the influence of noise, the X-ray intensity detected by the X-ray detector 30 varies. As shown in FIG. 2B, when the X-ray luminance of the X-ray source 10 is sufficiently high, solder, wiring patterns, air, etc. can be distinguished from each other even if the detection luminance has a width. However, as the luminance of the X-ray source 10 deteriorates, different members cannot be distinguished. In the example of FIG. 2B, the wiring pattern and the air cannot be distinguished from each other with the luminance at the usage time T2. As described above, if different members cannot be distinguished, stable inspection cannot be performed.

  In the conventional X-ray inspection apparatus, the X-ray source 10 is exchanged when the output of the X-ray source 10 becomes less than the luminance at which stable inspection cannot be performed. In the X-ray inspection apparatus according to the present embodiment, stable X-ray inspection can be continued by changing the imaging conditions even when the luminance of the X-ray source 10 falls to some extent. As a result, the use period of the X-ray source can be extended, and therefore maintenance costs can be suppressed.

<Luminance threshold>
A description will be given of the luminance threshold value B _TH at which stable X-ray inspection cannot be performed. The X-ray luminance detected by the X-ray detector 30 varies depending on the substrate to be inspected by the X-ray inspection apparatus 1. For example, if the number of multilayered substrates is large, the amount of X-ray absorption in the inspection object is different, so that the X-ray luminance detected by the X-ray detector 30 is different.

  Considering this point, there are two types of methods for determining the luminance threshold for determining that the X-ray inspection cannot be performed stably. The first method is a method in which only one threshold value is set in the X-ray inspection apparatus and the threshold value is made the same regardless of the type of inspection object. The second method is a method of setting a brightness threshold value for each type of inspection object.

  In the first method of setting one threshold value for the X-ray inspection apparatus, it is necessary to obtain the luminance of an X-ray source that can stably inspect all substrates to be inspected. This brightness can be determined experimentally. In a state where the distances between the X-ray source 10, the inspection object 20, and the X-ray detector 30 are fixed, X-ray imaging is performed while reducing the luminance of the X-ray source, and the luminance at which different materials cannot be distinguished is determined. . And the brightness | luminance of the X-ray detected in the X-ray detector 30 is measured in the state which remove | excluded the test target 20, keeping the X-ray output. Such measurement is performed on all the substrates to be inspected, and a luminance threshold value that can stably inspect all the substrates is obtained.

  Such a first method has an advantage that the apparatus configuration is simplified because it is not necessary to set a threshold value for each inspection target.

  In the second method of setting the threshold value for each inspection object, the threshold value is experimentally obtained in the same manner as described above, and the luminance threshold value is stored for each inspection object. This method has an advantage that an appropriate lifetime of the X-ray source can be determined according to the inspection target because the luminance threshold value can be determined for each inspection target.

<Control method>
With reference to FIG. 3, the process of the X-ray inspection apparatus 1 concerning this embodiment is demonstrated. FIG. 3 is a flowchart showing the flow of X-ray source life determination and imaging condition change processing for extending the life performed at the start of X-ray inspection.

  When the X-ray inspection apparatus 1 is activated (S100), the calculation unit 111 reads an inspection program from the auxiliary storage unit 113. This inspection program is a program in which a position to be measured and a measurement method thereof are automatically determined and stored in advance by teaching processing.

  The calculation unit 111 reads the initial shooting conditions (S101). Examples of the initial conditions include an X-ray source tube voltage of 80 kV, a tube current of 200 μA, a source-X-ray detector distance of 500 mm, and an exposure time of 125 ms.

  In accordance with a command from the imaging condition control unit 202, the X-ray source control unit 105, the imaging height control unit 106, the X-ray image imaging unit 102, and the like are controlled to set the read imaging conditions (S102). Then, imaging is performed to measure the deterioration state of the luminance of the X-ray source (S103). That is, X-rays are emitted from the X-ray source 10 and the X-ray detector 30 measures X-rays.

  The lifetime determination unit 201 compares the X-ray luminance detected by the X-ray detector 30 in step S103 with the luminance threshold stored in the luminance threshold holding unit 203, so that the X-ray source 10 has reached the lifetime. It is determined whether or not (S104). When one brightness threshold is set for the X-ray apparatus, the brightness threshold is compared with the detected X-ray brightness. When a luminance threshold is set for each inspection object, the luminance threshold corresponding to the inspection object to be inspected is compared with the detected X-ray luminance. The type of inspection object may be determined by receiving an input from the user, or may be determined by reading a barcode or the like attached to the inspection object.

  If the detected X-ray luminance is equal to or higher than the luminance threshold (S105-YES), it is determined that the X-ray source 10 has not yet reached the end of its life and a normal inspection can be performed, and the imaging condition changing process is terminated. On the other hand, if the detected X-ray luminance is less than the luminance threshold (S105-NO), the luminance deterioration of the X-ray source 10 proceeds, and it is determined that normal inspection cannot be performed as it is, and the imaging conditions after step S106 are determined. Perform the change process.

  In the following steps S106 to S115, the shooting condition control unit 202 determines a shooting condition that can be changed from a plurality of shooting conditions, and changes the shooting condition. The changed shooting condition is stored in the shooting condition storage unit 204 (S116). When the imaging conditions are changed, the X-ray imaging process and the life determination process (S102 to S104) are executed again under the imaging conditions. If sufficient luminance cannot be obtained even if one shooting condition is changed, another shooting condition is changed. This process is repeated until sufficient brightness is obtained in the life determination process. When sufficient luminance is obtained, the photographing condition changing process is terminated. If sufficient luminance cannot be obtained even if all the imaging conditions are changed, a warning is displayed indicating that the luminance of the X-ray source 10 has deteriorated and stable X-ray inspection cannot be performed (S117).

In the present embodiment, five shooting conditions can be changed. The five conditions are as follows (see FIG. 4).
Shooting conditions Shooting distance Shooting conditions Number of projections Shooting condition 3. Exposure time Shooting conditions X-ray source tube current Imaging conditions 5. X-ray source tube voltage

(1) Imaging distance The imaging distance is a distance between the X-ray source 10 and the X-ray detector 30. The closer this distance is, the more the X-ray dose irradiated per unit area of the X-ray detector 30 increases, so the contrast of the X-ray image is improved. Even when the imaging distance is changed, it is preferable to keep the imaging magnification (magnification rate) of X-ray imaging constant. Therefore, it is preferable that the distance between the X-ray source 10 and the X-ray detector 30 is reduced, and the distance between the X-ray source 10 and the inspection object 20 is also reduced accordingly.

  Since the height of the component installed on the board to be inspected differs depending on the type of board, in order to be able to measure a plurality of boards, as shown in FIGS. A certain amount of space is provided between the object 20 (conveying device 21). When this interval is m, the distance L1 between the X-ray source 10 and the inspection object 20 can be reduced to L1 '= L1-m. Therefore, the distance L2 between the X-ray source 10 and the X-ray detector 30 can be shortened to L2 ′ = L2 / L1 × L1 ′ under the condition that the enlargement ratio in the X-ray image is kept constant.

  The determination as to whether or not the shooting conditions can be changed with respect to the shooting distance (S106) is performed as follows. First, the minimum distance between the X-ray source and the inspection object is stored in the user input holding unit 205 according to the input from the user. Then, the current distance between the X-ray source and the inspection object is acquired from the imaging height control unit 106, and it is determined whether or not the imaging distance can be changed by comparing these values. Specifically, if the current distance between the X-ray source and the inspection object is larger than the minimum distance stored in the user input holding unit 205, it is determined that the imaging distance can be changed. Since the allowable minimum distance is determined by the type of inspection object, the allowable minimum distance for each inspection object is stored in advance, and the X-ray inspection apparatus recognizes the type of inspection object and responds accordingly. An allowable minimum value may be used.

  In the present embodiment, when changing the shooting distance, the shooting distance is changed so that the shooting distance becomes the shortest within an allowable range (S107). However, in another embodiment, the shooting distance may be shortened step by step.

(2) Number of projections The number of projections is the number of radiographs of one X-ray inspection. The X-ray inspection apparatus 1 according to the present embodiment performs X-ray imaging by irradiating an inspection target with X-rays from various directions in order to acquire a three-dimensional shape by an X-ray CT method. Specifically, with the X-ray source 10 fixed, imaging is performed while moving the inspection object on the circumference around the irradiation axis of the X-ray source in the XY plane. At this time, for example, 16 shots are taken while being moved by 2π / 16 (rad), or 32 shots are taken while being moved by 2π / 32 (rad). The number of times of imaging per inspection may be any number, but as the number of times of imaging increases, the resolution of the three-dimensional shape obtained increases and the inspection accuracy also improves. However, if the number of times of imaging is increased, the inspection time also increases accordingly.

The determination as to whether the number of projections can be changed (S108) is performed as follows. First, an inspection time allowed per inspection is accepted in advance as a user input. The input allowable inspection time is stored in the user input holding unit 205. If the inspection time before the imaging condition change is T, the allowable inspection time is T ₀ , and the current number of projections is N, the number of projections is
N ′ = T ₀ / T × N
Can be increased up to.

  Therefore, the imaging condition control unit 202 determines whether or not the number of projections can be increased by comparing the current number of projections with the maximum number of projections.

  In the present embodiment, when the number of projections is changed, the number of projections is increased to the maximum allowable number (S109). However, in another embodiment, the number of projections may be increased step by step within an allowable range.

(3) Exposure time The exposure time is a time for performing one X-ray imaging. As the exposure time is increased, the X-ray dose to be irradiated is increased, so that the contrast in the X-ray image is improved.

The determination as to whether or not the exposure time can be changed (S110) is performed as follows. First, an inspection time allowed per inspection is accepted in advance as a user input. The input allowable inspection time is stored in the user input holding unit 205. Note that the allowable inspection time is the same as that described in the column of the number of projections, and therefore it is not necessary to input and store the duplicate inspection time. The inspection time before shooting condition changes T, T ₀ the test time _allowed, the current exposure time by a T _E, exposure time,
T _E '= T ₀ / T × T _E
Can be increased up to.

  Therefore, the imaging condition control unit 202 determines whether or not the exposure time can be increased by comparing the current exposure time with the above-described maximum exposure time.

  In the present embodiment, when changing the exposure time, the exposure time is increased to the maximum allowable time (S111). However, in another embodiment, the exposure time may be increased stepwise within an allowable range.

(4) X-ray source tube current The output from the X-ray source 10 is proportional to the X-ray source tube current. Therefore, it is expected that the contrast of the X-ray image can be increased also by increasing the tube current of the X-ray source 10. The allowable tube current is determined for each X-ray source. Therefore, the imaging condition control unit 202 compares the tube current of the current X-ray source with the allowable maximum tube current, and can change the tube current if the current tube current is smaller than the allowable maximum tube current. (S112).

  In the present embodiment, when the tube current is changed, the tube current is changed so as to become the largest within the allowable range (S113). However, in another embodiment, the tube current may be increased stepwise.

(5) X-ray source tube voltage The output from the X-ray source 10 is proportional to the square of the tube voltage of the X-ray source. Therefore, it is expected that the contrast of the X-ray image can be increased also by increasing the tube voltage of the X-ray source 10. The allowable tube voltage is determined for each X-ray source. Therefore, the imaging condition control unit 202 compares the current tube voltage of the X-ray source and the allowable maximum tube voltage, and can change the tube voltage if the current tube voltage is smaller than the allowable maximum tube voltage. Is determined (S114).

  In the present embodiment, when the tube voltage is changed, the tube voltage is changed so as to become the maximum within an allowable range (S115). However, in another embodiment, the tube voltage may be increased stepwise.

<Operation / Effect of this Embodiment>
According to this embodiment, even when the X-ray source is deteriorated and the luminance is lowered, the imaging conditions are changed to improve the luminance detected by the X-ray detector. By automatically changing the imaging conditions in this way, the X-ray source can be used for a longer time, and maintenance costs can be suppressed.

<Modification>
In the above embodiment, the five shooting conditions of the shooting distance, the number of projections, the exposure time, the tube current, and the tube voltage can be changed. However, it is not always necessary to change all of these shooting conditions. Even if only a part (or even one) of these is set as the change target, the effect that the X-ray source can be used for a long time can be obtained. The priority for changing the plurality of shooting conditions is not limited to the above-described method, and may be changed in an arbitrary order.

  Further, in the luminance deterioration determination of the X-ray source, the luminance value detected by the X-ray detector by irradiating the X-ray from the X-ray source without placing the inspection object is used. It is also preferable to determine the luminance deterioration based on the value. For example, a luminance value obtained from an X-ray detector in a state where X-rays are irradiated from an X-ray source without placing an inspection object, and X in a state where no inspection object is placed and X-rays are not irradiated from the X-ray source. Based on the luminance value obtained from the line detector, a gain (ratio between the output intensity and the detected luminance value) is obtained, and when the gain falls below a predetermined value, it is determined that the luminance of the X-ray source has deteriorated. Also good.

  In the luminance deterioration determination of the X-ray source, it is also preferable to determine based on the luminance value detected by the X-ray detector by irradiating the X-ray from the X-ray source with the inspection object placed. In this case, the inspection object may be an actual inspection object or a calibration sample. The calibration (judgment) pattern is a pattern including, for example, solder, a wiring pattern, air, and the like. X-ray luminance at each pattern portion is acquired, and it is determined whether normal X-ray inspection is possible based on whether the luminance distribution is clearly separated for each pattern. When the luminance value ranges for different patterns overlap, these materials cannot be distinguished, and normal X-ray inspection cannot be performed. That is, it is determined that luminance degradation has occurred in the X-ray source. On the contrary, when the luminance value ranges for different patterns are separated, it can be determined that the X-ray source has no luminance deterioration and normal X-ray inspection can be performed.

  In the above description, an inspection apparatus that performs X-ray CT inspection has been described as an example. However, the present invention can be applied to any apparatus as long as it is an inspection apparatus that uses X-rays, such as an X-ray transmission inspection and an X-ray heating inspection. .

  1: X-ray inspection apparatus, 10: X-ray source, 20: inspection object, 30: X-ray detector, 111: calculation unit, 201: life determination unit, 202: imaging condition control unit, 203: luminance threshold holding unit 204: Shooting condition holding unit 205: User input holding unit

Claims (10)

An X-ray source for irradiating the inspection object with X-rays;
An X-ray detector for detecting X-rays;
Determining means for determining whether or not the X-ray source has deteriorated based on the luminance of the X-rays irradiated from the X-ray source and detected by the X-ray detector;
When it is determined that the X-ray source has deteriorated, imaging condition control means for changing imaging conditions in the X-ray inspection of the inspection object;
An X-ray inspection apparatus comprising: A moving means capable of changing a distance between the X-ray source and the inspection object;
The imaging condition control means reduces the distance between the X-ray source and the inspection object when it is determined that the X-ray source has deteriorated.
The X-ray inspection apparatus according to claim 1. In order to inspect the inspection object, multiple X-rays are taken,
The imaging condition control means increases the number of X-ray imaging when it is determined that the X-ray source has deteriorated,
The X-ray inspection apparatus according to claim 1. The imaging condition control means increases an exposure time in X-ray imaging when it is determined that the X-ray source has deteriorated.
The X-ray inspection apparatus according to claim 1. The imaging condition control means increases the tube current or tube voltage of the X-ray source when it is determined that the X-ray source has deteriorated.
The X-ray inspection apparatus according to claim 1. The photographing condition control means can change a plurality of photographing conditions,
After changing one shooting condition, the determination by the determination unit is performed again using the changed shooting condition,
Even in the changed imaging conditions, if it is determined that the X-ray source has deteriorated, another imaging condition is changed.
The X-ray inspection apparatus in any one of Claims 1-5. Even after changing all of the plurality of imaging conditions, if it is determined that the X-ray source has deteriorated, a warning indicating a decrease in luminance of the X-ray source is performed.
The X-ray inspection apparatus according to claim 6. The determination means determines whether or not the X-ray source has deteriorated according to one determination criterion regardless of the type of inspection object.
The X-ray inspection apparatus according to claim 1. The determination means determines whether or not the X-ray source has deteriorated according to a determination criterion according to the type of the inspection object.
The X-ray inspection apparatus according to claim 1. An X-ray source for irradiating the inspection object with X-rays;
An X-ray detector for detecting X-rays;
A method for controlling an X-ray inspection apparatus comprising:
X-ray irradiation from the X-ray source, the X-ray detector detects the brightness of the X-ray,
Based on the detected X-ray luminance, determine whether the X-ray source has deteriorated,
When it is determined that the X-ray source has deteriorated, the imaging conditions in the X-ray inspection of the inspection object are changed.
X-ray inspection apparatus control method.

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