X-ray inspection equipment

Abstract

The present invention provides an X-ray inspection system that can perform good inspections while increasing the speed of item transport and reducing the power output of the X-ray generator. [Solution] An X-ray inspection apparatus comprising an X-ray generator 21 that irradiates an object P under inspection with X-rays, an X-ray detector 22 that outputs detection data for each stage of multiple detection element arrays 22a, 22b arranged linearly in the transport direction in the main scanning direction Y, and an inspection processing unit 35 that generates an inspection image Dpx consisting of multiple pixels (xi, yj) having respective density values ​​based on the detection data, and inspects the quality of the object P under inspection based on the image, wherein the X-ray detector 22 has a scintillator 22s with good afterglow characteristics and CMOS type photoelectric sensors 22a, 22b that receive light emitted in response to the X-rays detected by it and output detection data Lxa, Lxb, and generates an inspection image Dpx from received light data Lx obtained by integrating the detection data of detection element arrays 22a, 22b in the TDI method.

Description

[Technical Field]

[0001] The present invention relates to an X-ray inspection apparatus, and more particularly to an X-ray inspection apparatus that inspects the quality of an object to be inspected, such as food or pharmaceuticals, based on X-ray image data. [Background technology]

[0002] In X-ray inspection equipment used to inspect the quality of orally ingested items such as food and medicine, including the presence of foreign matter or missing parts, and the presence of morphological defects in key parts such as contents and seals, there are known systems that irradiate items in transit with X-rays, detect the transmitted X-rays using the periodic detection operation of a line sensor to acquire two-dimensional image data, and then inspect the quality of the item being inspected based on predetermined image processing results for that image data.

[0003] In such X-ray inspection equipment, the X-ray output (tube voltage and tube current) from the X-ray generator is set for each type of object to be inspected so that the density distribution and contrast of the X-ray image are appropriate according to the thickness and transport speed of the object to be inspected.

[0004] Conventional X-ray inspection devices of this type store, for example, a set X-ray image associated with the variety information of the object to be inspected in memory in the form of a compressed image, thereby facilitating the accurate determination of inspection conditions for the selected variety when selecting a variety. In this device, the operating conditions of the X-ray detection means and the X-ray image generation unit are set for each variety to be inspected, and the X-ray image generated by the X-ray image generation unit is associated with the setting information for each variety and stored as the aforementioned set X-ray image information (see, for example, Patent Document 1).

[0005] Furthermore, to address the problem that reducing the X-ray output of the X-ray generator reduces the detection output of the X-ray detector, making it difficult to detect foreign objects with high sensitivity and thus hindering high-sensitivity X-ray inspection, a system is known that improves X-ray detection sensitivity and reduces X-ray output by synthesizing the detection data from the X-ray detector using the TDI (Time Delay Integral) method (see, for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2007-232586 [Patent Document 2] Japanese Patent Publication No. 2011-242374 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, with regard to the X-ray inspection equipment described above, the demands for not only improved inspection performance but also energy saving and extended lifespan have become more sophisticated, leading to the following challenges becoming apparent.

[0008] In other words, if the material handling speed is increased to meet the demand for improved productivity, and the output power of the X-ray generator is reduced to meet the demands for energy saving, miniaturization, and extended lifespan, the output level of the detection signal from the X-ray licensor will decrease further, resulting in a deterioration of the density resolution of the X-ray image.

[0009] Furthermore, in the case of indirect conversion type X-ray detectors, at scanning cycles corresponding to high transport speeds, the afterglow of the scintillator overlaps with the detection signal of the next scanning cycle of the line sensor, causing the image to blur and resulting in a deterioration of the spatial resolution of the X-ray image.

[0010] In response to this, it is conceivable that the demand for high-speed inspection with low power consumption can be met by employing a TDI-type line sensor camera with multiple rows of line sensors in the X-ray detector to increase detection sensitivity, and by using a CMOS sensor suitable for low power consumption and miniaturization of X-ray inspection equipment in the line sensor camera.

[0011] However, simply adopting a CMOS sensor in a line sensor camera is insufficient in terms of light output from the scintillator, which is a problem in X-ray inspection equipment used to inspect the quality of food products, due to the diversity of product types, thicknesses, and packaging forms. Therefore, it was necessary to use a scintillator with high light output rather than one with low light output and short afterglow time. Consequently, despite the reduction of noise using the TDI method, an unresolved problem remains: the X-ray image tends to be blurry and the detection sensitivity tends to be low due to the poor temporal resolution of the detection data from the line sensor camera.

[0012] Therefore, the present invention aims to provide an X-ray inspection apparatus that can perform good inspections while increasing the speed of article transport and reducing the power output of the X-ray generator. [Means for solving the problem]

[0013] (1) To achieve the above objective, the X-ray inspection apparatus according to the present invention comprises: an X-ray generator that irradiates an object to be inspected passing through a transport path with X-rays; an X-ray detector having multiple stages in the transport direction of a plurality of detection element rows, each consisting of a plurality of detection elements arranged linearly in the main scanning direction perpendicular to the transport direction of the object to be inspected, and outputting detection data obtained from each detection element for each stage of the plurality of stages of detection element rows; and an inspection processing unit that generates an inspection image consisting of a plurality of pixels having respective density values ​​based on the detection data output by the X-ray detector, and inspects the quality of the object to be inspected based on the inspection image, wherein the X-ray detector has a scintillator with good afterglow characteristics for detecting X-rays and a CMOS type photoelectric sensor that receives light emitted in response to the X-rays detected by the scintillator and outputs detection data, and generates the inspection image using received light data obtained by integrating the detection data of the plurality of stages of detection element rows in the TDI method.

[0014] In this configuration, the present invention converts an optical image from a scintillator with good afterglow characteristics for detecting X-rays into an optical image by a CMOS-type photoelectric sensor, obtaining detection data for multiple stages of detection element arrays (line sensors) of an X-ray detector. This detection data is then integrated using the TDI method to obtain imaging data, and an inspection image is generated based on this imaging data. During the generation of the inspection image, the scintillator with good afterglow characteristics ensures that a predetermined amount of light is emitted within the scanning cycle of each stage of detection element array, and that the afterglow is short enough so that it does not overlap with the detection signal of the next cycle of each stage of detection element array. This effectively suppresses blurring of the inspection image obtained from the imaging data of multiple stages of detection element arrays. Therefore, in addition to generating inspection images with low noise even in high transport speed regions by using the TDI method imaging with a CMOS sensor, the blurring of the X-ray image is effectively suppressed by improving the temporal resolution of the scintillation light, ensuring the required detection sensitivity and enabling good X-ray inspection.

[0015] Here, "good afterglow characteristics" means that the amount of light emitted (luminance) of the scintillator is obtained to a degree that allows for the generation of low-noise inspection images even in the high transport speed region by TDI imaging, and that the decay time (decay time constant) of the scintillator's light emission intensity is sufficiently shorter than the scanning period of each stage of the X-ray detector's detection element array. More preferably, the decay time is shorter than the scanning period of each stage of the X-ray detector's detection element array during high-speed transport, and particularly preferably, the decay time is half or less of the scanning period of each stage of the X-ray detector's detection element array during high-speed transport.

[0016] (2) In a preferred embodiment of the present invention, there are provided inspection condition detection means for detecting that a specific inspection condition for degrading the image quality of the inspection image is satisfied, and image data adjustment means for adjusting the detection data output from the X-ray detector so as to improve the image quality of the inspection image when the inspection condition detection means detects that the specific inspection condition is satisfied. An inspection image with an expanded range of the density value is generated based on the adjusted detection data adjusted by the image data adjustment means, and the inspection processing unit executes the inspection processing based on the data of the inspection image with the expanded range of the density value.

[0017] In this case, by expanding the range of the density value of the inspection image by binning processing or kernel processing, it is possible to reduce the image while suppressing the loss of information due to pixel decimation. Even when the conveyance speed of the object to be inspected is increased or the output of the X-ray generator is reduced as described above, the influence of the decrease in the signal level of the detection signal can be more effectively suppressed, and good inspection processing can be executed.

[0018] (3) The specific inspection condition can be configured to include a condition that the conveyance speed of the object to be inspected passing through a predetermined section on the conveyance path has reached a predetermined speed or higher, or that the irradiation intensity of the X-ray irradiated from the X-ray generator to the object to be inspected has decreased below a predetermined intensity.

[0019] In this case, when the specific inspection condition for degrading the image quality of the inspection image is satisfied, the detection data output from the X-ray detector is adjusted so as to improve the image quality of the inspection image. Therefore, the required image quality of the inspection image can be ensured, and good inspection processing can be executed.

[0020] (4) In a preferred embodiment of the present invention, there may be provided height setting means for setting a reference height from the conveyance surface of the conveyance path, and scanning condition setting means for setting the scan period in the main scanning direction and the delay time in the conveyance direction of the X-ray detector so that the aspect ratio on the transmission image at the reference height becomes 1.

[0021] In this case, the scan period in the main scanning direction of the X-ray detector and the delay time for integration processing in the TDI method are variably set so that the aspect ratio on the transmitted image at the reference height becomes 1. Therefore, the resolution in each coordinate axis direction of the two-dimensional inspection image is obtained uniformly, and the effect of the time-delay integral of the TDI method is accurately obtained.

[0022] (5) In a preferred embodiment of the present invention, the system can be configured to include a storage means for storing a reference height set by the height setting means for each product type. In this case, a suitable reference height, such as the height center or the center of gravity height, can be set for each product type, and the time it takes for each part of the planar cross-sectional area of ​​that reference height to pass between adjacent front-side detection element rows and rear-side detection element rows in the transport direction can be used as the transport direction delay time for the TDI method integration process. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide an X-ray inspection apparatus that can perform good inspections by combining a scintillator with good afterglow characteristics to the extent that the afterglow does not overlap with the detection signal of the next cycle of the line sensor, while increasing the speed of article transport and reducing the output of the X-ray generator, and a CMOS sensor suitable for low power consumption, and by ensuring the required detection sensitivity by TDI-type X-ray detection. [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic diagram showing an X-ray inspection apparatus according to one embodiment of the present invention. [Figure 2] This diagram shows the configuration of the X-ray detection unit in an X-ray inspection apparatus according to one embodiment of the present invention, where (a) is an explanatory diagram of the arrangement of an X-ray generator and an X-ray detector spaced apart above and below the transport surface, (b) is a front view of the main part of the X-ray generator as seen in the Y direction (main scanning direction) in (a), and (c) is a front view of the main part showing another embodiment of the X-ray generator. [Figure 3]This is an explanatory diagram of the TDI method for image data processing in an X-ray detector having a CMOS type photoelectric sensor in an X-ray inspection apparatus according to one embodiment of the present invention. [Figure 4] This is an explanatory diagram of the binning process of X-ray image data performed according to the transport speed of the object to be inspected in an X-ray inspection apparatus according to one embodiment of the present invention. [Modes for carrying out the invention]

[0025] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[0026] [One embodiment] Figures 1 to 4 show an X-ray inspection apparatus according to one embodiment of the present invention.

[0027] First, let me explain the structure.

[0028] As shown in Figure 1, an X-ray inspection apparatus 1 according to one embodiment of the present invention has an article transport unit 10, an X-ray inspection unit 20, a control unit 30, and a display operation unit 40, and constitutes part of an inspection system that includes a sorting device (not shown) located downstream of the article transport unit 10.

[0029] This X-ray inspection device 1 is a device that inspects an object P under inspection using X-rays, which are classified as electromagnetic waves that can penetrate the object P under inspection. For example, it has a foreign object detection function that can determine whether or not foreign objects are mixed in the object P under inspection using X-rays. However, it may also have functions other than foreign object detection, such as missing item inspection, mass inspection, inspection of the shape of the object under inspection such as thickness and length, and detection of packaging defects such as contents being caught in the seal. Furthermore, the present invention uses a scintillator, which will be described later, and it goes without saying that the radiation classified as electromagnetic waves is not limited to X-rays, but also includes inspection of goods using other types of radiation.

[0030] (Structure of the Inspection Department) The article transport unit 10 of the X-ray inspection apparatus 1 has a belt 11 that is looped over a pair of parallel rollers 12 and 13, and the transport path 11a, which is the upper part of the belt 11, is configured to transport the object to be inspected P in a predetermined transport direction, X. The article transport unit 10 also includes a transport drive motor M (not shown) that rotates one of the rollers 12 or 13 at a variable set speed to advance the belt 11 at a predetermined transport speed V, and an encoder E for detecting the rotation speed. Furthermore, the predetermined transport speed V at which the article transport unit 10 transports the object to be inspected P is pre-set as part of the product setting information according to the product type (for example, according to the X-ray transmittance described later) when the product type of the object to be inspected P is registered. It goes without saying that although a belt conveyor is used here, the object to be inspected P may also be transported by other types of conveyors.

[0031] The X-ray inspection unit 20 of the X-ray inspection apparatus 1 includes an X-ray generator 21 (radiation source) that irradiates the object to be inspected P passing through an inspection area Z1 which is a predetermined section on the transport path 11a with X-rays, and a line sensor type X-ray detector 22 (radiation detection unit) that detects the dose of X-rays that have passed through the object to be inspected P (hereinafter referred to as the X-ray transmission amount).

[0032] Although the detailed shape is not shown, the X-ray inspection unit 20 forms an article passage space within its housing installation area Z2 that extends within a predetermined height range on the transport path 11a. In this article passage space, a leaded curtain C1 is provided on the entrance side, separating the inspection area Z1 from the passage space on the entrance side, and a leaded curtain C2 is provided on the exit side, separating the inspection area Z1 from the passage space on the exit side. These leaded curtains C1 and C2 on the entrance and exit sides are of the noren curtain type, which can open and close the entrance and exit of the housing installation area Z2 of the X-ray inspection device 1. Each curtain consists of multiple flexible X-ray shielding curtains supported at their upper ends, arranged adjacent to each other in the Y direction, which is the width direction of the passage.

[0033] The X-ray generator 21 is an X-ray irradiation unit that irradiates X-rays, which are electromagnetic waves, onto the object to be inspected P as it moves at a predetermined transport speed V within the inspection area Z1 on the transport path 11a of the item transport unit 10.

[0034] This X-ray generator 21 has, for example, an X-ray tube 21a inside a metal box 21b, and the X-ray tube 21a is immersed in a cooling insulating oil (not shown) inside the box 21b. The X-ray tube 21a, although a detailed explanation of its structure is omitted, is configured such that electrons emitted from the cathode-side filament within the enclosure and focused by a focusing electrode collide with a target on the anode side opposite the filament, and the X-rays generated from that target are irradiated onto the transport path 11a.

[0035] The X-ray tube 21a is arranged, for example, so that its longitudinal direction is approximately parallel to the X-direction. The X-rays generated by the X-ray tube 21a in the X-ray generator 21 are irradiated downwards from the X-ray window 21c on the bottom side of the box 21b, perpendicular to the transport direction. The anode of the X-ray tube 21a may be of a fixed type or a rotating type. The X-ray window 21c may also have a collimator function that restricts the X-ray irradiation field to a predetermined shape.

[0036] The X-ray generator 21 configured in this way irradiates an X-ray beam Br with a predetermined beam shape, such as a fan beam shape as shown by the dashed lines in Figures 1 and 2, which is directed perpendicular to the X direction at a predetermined position in the transport direction of the item transport unit 10. This irradiates the object to be inspected P passing through the inspection area Z1 with X-rays at an irradiation intensity within a predetermined range, and causes the X-rays that have passed through the object to be inspected P to be incident on the line sensor type X-ray detector 22.

[0037] The X-ray inspection unit 20's X-ray detector 22 has multiple rows of detection element arrays 22a and 22b arranged linearly with the Y direction, which is perpendicular to the X direction, which is the transport direction of the object P under inspection, as its main scanning direction, and at least two rows as shown in Figure 2(b). The multiple rows of detection element arrays 22a and 22b are arranged adjacent to each other and parallel to each other in the X direction, which is the transport direction of the object.

[0038] Furthermore, as shown in Figure 2, each of the multi-stage detection element arrays 22a and 22b consists of multiple adjacent X-ray detection elements e1~e in the Y direction. N It consists of multiple rows of X-ray detection elements e1~e, each aligned in the Y direction. N These are aligned and arranged so that they are adjacent to each other in the X direction at each detection position (the detection position for each element number). The X-ray detector 22 is also positioned on the lower side of the transport path 11a, which is inside the loop-shaped belt 11 of the article transport unit 10. Here, for example, multiple X-ray detection elements e1~e N Assuming that the width of each sensor in the X direction is 1 mm, the gap between sensors is negligibly small compared to the sensor width, and the width in the Y direction, which is the width direction of the transport path 11a that transports the object P to be inspected, is 200 mm, then each stage of detection element arrays (hereinafter referred to as each stage of detection element arrays 22i) will have approximately 200 X-ray detection elements e1~e N This means that a line sensor with the following characteristics can be used.

[0039] The X-ray detector 22 may have three or more stages, for example, four stages of detection element arrays 22a, 22b, 22c, 22d as shown in Figure 2(c), or five or more stages of detection element arrays 22a, 22b, etc. However, in the case of multiple stages of detection element arrays 22a, 22b, etc., each stage of detection element array 22i may consist of multiple X-ray detection elements e1~e N It consists of multiple rows (multiple sets) of X-ray detection elements e1~e such as the multiple rows of detection element arrays 22a, 22b, etc. N These elements are aligned and arranged so that they are adjacent to each other in the X direction at the detection position of each element number.

[0040] The X-ray detector 22 also has a sheet-like scintillator 22s with good afterglow characteristics attached to the incident surface side of the multiple stages of detection element arrays 22a and 22b. The multiple stages of detection element arrays 22a and 22b emit light (optical image) in response to the X-rays detected by the scintillator 22s (X-rays transmitted through the object P under inspection), and the multiple X-ray detection elements e1 to e in each stage of the detection element array 22i NIt is composed of a CMOS type photoelectric sensor that receives light at a predetermined main scanning period and sequentially outputs detection data Lxa and Lxb.

[0041] The main scanning in each stage of the detection element array 22i is performed at least once during a predetermined delay time t1 corresponding to the distance d between detection positions and the conveyance speed V, and the period of the main scanning is shorter than the predetermined delay time t1 used for the imaging data processing of the TDI method. N The main scanning in each stage of the detection element array 22i is performed at least once during a predetermined delay time t1 corresponding to the distance d between detection positions and the conveyance speed V, and the period of the main scanning is shorter than the predetermined delay time t1 used for the imaging data processing of the TDI method.

[0042] Here, based on the reference height hc such as the center height and the centroid height of the inspected object P, the arrangement of the plurality of stages of detection element arrays 22a and 22b of the X-ray generator 21 and the X-ray detector 22 and the detection center distance d, the conveyance speed V of the article conveyance unit 10 corresponding to the type of the inspected object P, the height H1 of the X-ray generation position of the X-ray generator 21 on the conveyance path 11a, and the X-ray generation height H2 from the detection surface P0 of the plurality of stages of detection element arrays 22a and 22b of the X-ray detector 22 to the target of the X-ray generator 21, when calculating a predetermined delay time t1 corresponding to the reference height hc of the inspected object P, the predetermined delay time t1 is calculated by the following formula [1].

[0043] t1 = {(H1 - hc) / H2}·(d / V) ···[1] In the following description, for convenience of explanation, the period (scan period) of the main scanning for scanning a plurality of X-ray detection elements e1 to e in each stage of the detection element array 22i is referred to as the main scanning period t2. N In the following description, for convenience of explanation, the period (scan period) of the main scanning for scanning a plurality of X-ray detection elements e1 to e in each stage of the detection element array 22i is referred to as the main scanning period t2.

[0044] The plurality of stages of detection element arrays 22a and 22b composed of CMOS type photoelectric sensors have an element array in which a plurality of sets of X-ray detection elements e1 to e are adjacent to each other in the X direction at the detection positions of each element number. N Since the plurality of X-ray detection elements e1 to e in each stage of the detection element array 22i have an element array in which a plurality of sets of X-ray detection elements e1 to e are adjacent to each other in the X direction at the detection positions of each element number, when the plurality of X-ray detection elements e1 to e in each stage of the detection element array 22i output electrical signals corresponding to the amount of light from the scintillator 22s, the plurality of columns of X-ray detection elements e1 to e of the plurality of stages of detection element arrays 22a and 22b N Since the plurality of X-ray detection elements e1 to e in each stage of the detection element array 22i have an element array in which a plurality of sets of X-ray detection elements e1 to e are adjacent to each other in the X direction at the detection positions of each element number, when the plurality of X-ray detection elements e1 to e in each stage of the detection element array 22i output electrical signals corresponding to the amount of light from the scintillator 22s, the plurality of columns of X-ray detection elements e1 to e of the plurality of stages of detection element arrays 22a and 22b NThe detected data Lxa and Lxb are shifted in detection timing according to the distance d between detection positions and the transport speed V, and are data that can be processed by integrating them using the TDI method.

[0045] Here, "good afterglow characteristics" means that the amount of light emitted (brightness) of the scintillator 22s is sufficient to generate inspection images with low noise even in the high transport speed region by TDI imaging (for example, about 40% or more, preferably 60% or more, compared to the brightness of conventional products with high light emission), and that the decay time (decay time constant) of the light emission intensity of the scintillator 22s is sufficiently shorter than the scanning period t2 (usually several hundred milliseconds) of each stage of the detection element array 22i of the X-ray detector 22, and more preferably, that decay time is shorter than the scanning period t2 (usually several hundred milliseconds) of each stage of the detection element array 22i of the X-ray detector 22 during high-speed transport. The decay time of the sub-array 22i is shorter than the scanning period t2 of the sub-array 22i (for example, if the transport speed is 80 m / min and the transport direction resolution is 0.2 mm, the transport time for one pixel in the X direction (sub-scanning direction) is 150 μs (approximately 6.7 kHz), and the scan time for one scan in the Y direction (main scanning direction) is 150 μs / scan). Particularly preferable is that the decay time is less than or equal to half the scanning period t2 of the detection element array 22i of each stage of the X-ray detector 22 during high-speed transport (for example, if the transport speed is 80 m / min and the transport direction resolution is 0.2 mm, then 75 μs or less).

[0046] (Configuration and functions of the control unit) Although the detailed configuration of the control unit 30 is not shown, it is realized by a combination of hardware such as a CPU (Central Processing Unit) and RAM (Random Access Memory), and software such as programs that perform various functions on that hardware. The hardware referred to here may include FPGAs (Field Programmable Gate Arrays) and DSPs (Digital Signal Processors). The various functions referred to here are the functions of the following multiple functional units that perform tasks such as acquiring and outputting detection data capable of generating an X-ray image of the object under inspection P, generating inspection image data, and controlling predetermined inspection processing and display output.

[0047] As shown in Figure 1, the control unit 30 is configured as a plurality of functional units that perform the aforementioned functions, including a detection data output unit 31, a level conversion processing unit 32 (image data adjustment means), a variety control unit 33 (inspection condition detection means), an image generation unit 34, an inspection processing unit 35 (inspection image processing means), a determination unit 36, a deterioration detection unit 37 (inspection condition detection means), and a condition setting unit 38 (height setting means, scanning condition setting means). Based on variety information and various detection information pre-set in the variety control unit 33, it performs predetermined X-ray inspection and control of display output for the object to be inspected P.

[0048] Here, the detection data output unit 31 outputs the X-rays that have passed through the object P from the X-ray generator 21 toward the object P to be inspected to a plurality of X-ray detection elements e1~e N Each of these is configured to perform a detection operation, i.e., a main scan, which is performed at a predetermined interval.

[0049] Furthermore, since the multi-stage detection element arrays 22a and 22b, which are composed of CMOS-type photoelectric sensors, have a detection element arrangement that enables TDI (Time Delay Integration) imaging data processing, the detection data output unit 31 performs imaging data processing that integrates the detection data Lxa and Lxb from the multi-stage detection element arrays 22a and 22b using the TDI method with a predetermined delay time t1 corresponding to the distance d between the detection positions of both detection element arrays 22a and 22b and the transport speed V of the object being audited, and outputs the detection data Lx after the imaging data processing.

[0050] The image data processing referred to here is, for example, as shown in Figure 3, when the transport time from when the tip of the object under inspection P is detected by the object detection sensor 81 until the tip of the reference height surface A of the object under inspection P reaches the detection position x1 in the figure by the preceding detection element array 22a is defined as a waiting transport time t0 or a waiting transport time t0 + n·t1 (where n is a natural number corresponding to a multiple of the passage time of a delay time t1 relative to the detection position x1), the detection data Lxa from the preceding detection element array 22a is defined as detection data D1 for each delay time t1 after the tip of the reference height surface A of the object under inspection P reaches the detection position x1 in the figure by the preceding detection element array 22a, and the detection data Lxb from the subsequent detection element array 22b adjacent to the preceding detection element array 22a is defined as detection data D2 for each delay time t1 after the tip of the reference height surface A of the object under inspection P reaches the detection position x2 in the figure by the subsequent detection element array 22b, then each detection element e1~e in the detection data D1 on the preceding side N The image density value corresponding to the X-ray attenuation amount of pixels on each main scan line corresponding to the detection data, and each detection element e1~e in the subsequent detection data D2. N This involves an integration process (TDI → D1 + D2 in the figure) where the detection data is added together with the image density value corresponding to the X-ray attenuation amount of the pixel on each main scanning line.

[0051] The level conversion processing unit 32 is an image data adjustment means that adjusts the detection data Lx output from the detection data output unit 31 in order to improve the image quality of the inspection image generated by the image generation unit 34 when the variety control unit 33 and the deterioration detection unit 37 detect that specific inspection conditions have been met.

[0052] Specific inspection conditions are, for example, conditions in which the irradiation intensity of X-rays from the X-ray generator 21 to the object P under inspection is insufficient, or the irradiation time of X-rays is insufficient. The adjustment performed by the level conversion processing unit 32 when specific inspection conditions are met is functionally equivalent to a process that expands the range of density values ​​of the image, that is, a process that adjusts the brightness of the image according to the exposure amount (X-ray irradiation time and irradiation intensity), similar to the gain adjustment of a digital camera. Specifically, this can be a binning process or kernel processing (filtering process) as illustrated in Figure 4.

[0053] The variety control unit 33 stores variety setting information, which is pre-set and registered for each variety of the item to be inspected P, in memory. Based on this variety setting information (for example, variety number, item name, number of contents, weight, shape, tube current, tube voltage, transport speed, judgment threshold, mask processing conditions, etc.), it variably sets various parameters related to the inspection conditions and has the function of controlling the item transport unit 10, X-ray inspection unit 20, control unit 30, and display operation unit 40 to the operating conditions required according to the variety.

[0054] Furthermore, when a variety is selected by a selection operation from the display operation unit 40, the variety control unit 33 identifies inspection conditions based on the setting information of that variety and other detection information, and has the function of an inspection condition detection means that detects in advance whether specific inspection conditions are met that would degrade the image quality of the inspection image generated by the image generation unit 34, for example, whether the transport speed V of the object to be inspected P passing through the inspection area Z1 on the transport path 11a reaches a predetermined speed or higher, or whether the X-ray transmittance of the object to be inspected P in the X-ray transmission direction is within the low transmittance range of a plurality of preset transmittance ranges.

[0055] The image generation unit 34 scans multiple X-ray detection elements e1~e for each main scan of the multiple detection element arrays 22a, 22b of the X-ray detector 22. N Based on the detection data Lx output from the detection data output unit 31 after TDI-based imaging data processing in response to the detection signal, an inspection image Dpx consisting of multiple pixels, each having its own density value, is generated.

[0056] The inspection processing unit 35 is configured to perform a predetermined inspection process to inspect the predetermined quality of the object P based on the data of the inspection image Dpx of the object P. The predetermined inspection process here refers to a function that performs image processing suitable for judgment processing and visual confirmation work in order to automatically and / or visually determine whether or not there are foreign objects or missing parts in the object P using X-rays (more specifically, image processing that sets the grayscale level based on the result of logarithmically transforming the detection signal level according to the sensitivity of the human eye, processing that emphasizes and sharpens the abrupt changes in image density values ​​near the contour of foreign objects, and processing that detects edges and lines corresponding to the contours of foreign objects and fixed-shape contents). Of course, depending on the required inspection content, the inspection processing unit 35 may also have a function that performs image processing suitable for mass inspection, inspection of the shape of the object, such as the thickness and length of the object, and detection of packaging defects such as contents being caught in the seal, rather than inspection image processing for foreign object detection or missing parts.

[0057] The determination unit 36 ​​uses image data of the object P to be inspected, which has been processed by the inspection processing unit 35, to execute a known predetermined determination processing program that uses key parameters that specify the determination conditions for X-ray inspection for each product type, such as foreign object detection limit, foreign object area ratio, and density limit, to determine whether the quality of the object P to be inspected is acceptable or unacceptable. For example, after applying image processing suitable for the determination processing to the inspection image, the determination unit 36 ​​compares it with a predetermined threshold to determine whether or not there are foreign objects such as metal foreign objects with high X-ray absorption rates, and sequentially outputs the determination result on the touch panel screen of the display operation unit 40.

[0058] The deterioration detection unit 37 has a deterioration detection function that detects a predetermined deterioration state of the X-ray generator 21 and the X-ray detector 22, and supplies the deterioration detection information as detection information to the variety control unit 33, which is an inspection condition detection means. In other words, the deterioration detection unit 37 works in cooperation with the variety control unit 33 to identify inspection conditions based on the variety setting information and inspection conditions based on other detection information when a variety is selected, and also has the function of an inspection condition detection means that detects in advance when a variety is selected whether specific inspection conditions that degrade the image quality of the inspection image generated by the image generation unit 34 are met.

[0059] Furthermore, the degradation detection unit 37 can estimate and calculate the vacuum level of the X-ray tube 21a as it deteriorates over time, and has the function of estimating the remaining lifespan and degree of deterioration of the X-ray tube 21a based on the calculated vacuum level. This function of measuring the vacuum level of the X-ray tube 21a and estimating the remaining lifespan is similar to that of an X-ray generator that utilizes the principle of an ionization vacuum gauge, as disclosed in International Publication No. 2019 / 117172, and from its remaining lifespan, it is possible to determine whether the X-ray irradiation intensity has decreased to below a predetermined intensity due to the deterioration of the X-ray tube 21a over time, and whether it has reached a level that can induce deterioration of the image quality of the inspection image.

[0060] In other words, the aforementioned specific inspection conditions include conditions such as the transport speed of the object to be inspected passing through the inspection area Z1 on the transport path 11a reaching a predetermined speed or higher, or the irradiation intensity of the X-rays irradiated onto the object to be inspected P from the X-ray generator 21 being below a predetermined intensity, or conditions such as the transmittance of the object to be inspected P in the X-ray transmission direction being within the low transmittance range among a plurality of preset transmittance ranges, or a significant decrease in the detection sensitivity of the X-ray detector 22 being detected.

[0061] Furthermore, the aforementioned specific inspection conditions may be set in stages such that a specific inspection condition is met when either of the following conditions is met: a first specific transport condition in which the transport speed of the object to be inspected P passing through the inspection area Z1 on the transport path 11a of the article transport unit 10 is equal to or greater than a first transport speed (e.g., 40 m / min) which is a predetermined speed that is relatively faster than the normal transport speed for the same type of product, and is less than a second specific transport speed (e.g., 90 m / min) which is higher than the first transport speed; or a second specific transport condition in which the transport speed is in the high transport speed range of the second transport speed or higher.

[0062] The level conversion processing unit 32 may also change its processing function for adjusting the detection data of the object under inspection P such that the amount of adjustment of the detection data of the object under inspection P increases when the second specific transport condition is detected by the variety control unit 33 and / or the deterioration detection unit 37, compared to when the first specific transport condition is detected by the variety control unit 33 and / or the deterioration detection unit 37.

[0063] Specifically, the detection data Lx output from the detection data output unit 31 can generate an X-ray image Dpx of part or all of the object P under inspection, and when a segment image Sim1 corresponding to a predetermined number of adjacent pixel groups is obtained from this X-ray image Dpx, the level conversion processing unit 32 usually performs a predetermined binning process according to the detection information of the variety control unit 33 and / or the deterioration detection unit 37, which are inspection condition detection means, as shown in Figure 4.

[0064] In this case, the level conversion processing unit 32 divides the segment image Sim1 into multiple subsegment regions S1a, S1b, S1c, and S1d (small regions) in a binning manner. The 32 uses multiple pixel values ​​corresponding to the density values ​​(charges of the detected signal) within each small region as processing units (in Figure 3, for example, the pixel values ​​in the upper left subsegment region S1a of the segment image Sim1 before binning are shown as "1", "2", "5", and "6" indicating their respective pixel positions) and performs a binning process to integrate them into a single pixel value corresponding to one density value (in the same figure, for example, the upper left pixel value in the segment image Sim2 after binning is shown as "1" indicating its pixel position). As a result, the level conversion processing unit 32 adjusts the pixel value data corresponding to the density values ​​of the X-ray image data of the object under inspection P to improve the image quality of the inspection image while reducing the size of the inspection image, thereby improving the signal-to-noise ratio (S / N) and increasing the image processing speed.

[0065] The binning process here may be either a process of integrating multiple pixel values ​​corresponding to multiple density values ​​within each binned sub-region into a single pixel value, or a process of integrating multiple pixel values ​​into a single pixel value obtained by averaging them. In the former case, there is an effect similar to improving the signal-to-noise ratio by increasing the signal level of the detection signal from the X-ray detector 22, while in the latter case, there is an effect similar to improving the signal-to-noise ratio by reducing the noise component.

[0066] Furthermore, while binning is described here as a suitable example of processing for adjusting the detected data, kernel processing (filtering with a predetermined kernel size) for density conversion, such as expanding the dynamic range of density values ​​in the inspection image, can also be performed, which can contribute to improving the signal-to-noise ratio (S / N).

[0067] When the variety control unit 33 detects that a first specific transport condition has been set based on the set value of the transport speed V included in the variety information of the inspected object P by the item transport unit 10, the level conversion processing unit 32 sets the bin division size to 2×2 as shown in Figure 4, and when the variety control unit 33 detects that a second specific transport condition has been set, it sets the bin division size to 4×4 and executes binning processing with different adjustment amounts for each case.

[0068] Therefore, the level conversion processing unit 32 performs binning processing for each specific transport condition, such that the amount of adjustment made when the variety control unit 33 detects that a second specific transport condition has been set is greater than the amount of adjustment made when the variety control unit 33 detects that a first specific transport condition has been set.

[0069] Furthermore, as shown in Figure 4, when the transport speed V of the object to be inspected P passing through the inspection area Z1 on the transport path 11a of the item transport unit 10 is less than the normal transport speed range for the same type of product, for example, less than 40 m / min, and the product control unit 33 does not detect that the specific inspection conditions have been met, the level conversion processing unit 32 sets the bin division size to 1 × 1 and does not perform the binning process.

[0070] In addition to the data adjustments performed by the level conversion processing unit 32, the product type control unit 33 may also control the tube voltage of the X-ray tube 21a, which is the X-ray irradiation condition of the X-ray generator 21, to different voltage values ​​depending on whether the transport speed V of the object to be inspected P passing through the inspection area Z1 on the transport path 11a of the article transport unit 10 is on the lower end of the normal transport speed range for the same product type (e.g., 10 to 19 (m / min)) or on the higher end of the normal transport speed range (e.g., 20 to 39 (m / min)).

[0071] Furthermore, even when the product type control unit 33 determines that specific inspection conditions are met, it may control the tube voltage of the X-ray tube 21a, which is the X-ray irradiation condition of the X-ray generator 21, to a different voltage value depending on whether the transport speed of the object to be inspected P passing through the inspection area Z1 on the transport path 11a of the article transport unit 10 is set to a first transport speed (e.g., 40 m / min) or more and less than the second transport speed (e.g., 90 m / min), or whether the transport speed of the object to be inspected P passing through the inspection area Z1 on the transport path 11a of the article transport unit 10 is set to a first transport speed (e.g., 40 m / min) or more and less than the second transport speed (e.g., 90 m / min), or whether the transport speed of the object to be inspected is set to a second transport speed (e.g., 50 m / min) or more and more.

[0072] In other words, the variety control unit 33 can be configured to control the tube voltage of the X-ray tube 21a to a different voltage value from other transport speed ranges in a specific transport speed range before or after switching between the first specific transport conditions and the second specific transport conditions.

[0073] When the tube voltage of the X-ray tube 21a of the X-ray generator 21 is high, it can irradiate X-rays with a relatively short wavelength and relatively strong penetrating power, and when the tube voltage is low, it can irradiate X-rays with a relatively long wavelength and relatively weak penetrating power.

[0074] Therefore, the level conversion processing unit 32 and the variety control unit 33 have the function of improving the signal-to-noise ratio (S / N) by variably setting the tube voltage of the X-ray tube 21a, which is the X-ray irradiation condition of the X-ray generator 21. This not only reduces the size of the inspection image while adjusting the pixel value data corresponding to the density value of the X-ray image data of the object under inspection P to the side that improves the image quality of the inspection image through binning processing in the level conversion processing unit 32, but also by variably setting the tube voltage of the X-ray tube 21a.

[0075] The display operation unit 40 is a flat panel display that can input requested information to the control unit 30 in response to operation inputs, and can display the variety list and variety setting information stored in the variety control unit 33 on the screen.

[0076] The control unit 30 further includes a condition setting unit 38 that, in cooperation with the display operation unit 40, performs the functions of a height setting means for setting a reference height hc from the transport surface of the transport path 11a, and a scanning condition setting means for setting the scan period in the main scanning direction (Y direction) and the delay time t1 in the transport direction (X direction) of the X-ray detector 22 so that the aspect ratio on the transmitted image at the reference height hc becomes 1. This condition setting unit 38 has a memory 38a as a storage means for storing the reference height set for each product type by the function of the height setting means.

[0077] (action) Next, the operation of this embodiment will be described.

[0078] In the X-ray inspection apparatus 1 of this embodiment, configured as described above, first, prior to inspection, the type of the object to be inspected P is registered, and at that time, the reference height hc for X-ray inspection is input from the display operation unit 40 or the touch panel of another information terminal connected to it via data communication.

[0079] Specifically, when the height hp of the object to be inspected P is input from an input interface implemented in the display operation unit 40 when the type of object to be inspected P is registered, or when it is measured by an object height measuring sensor (not shown), the reference height hc for X-ray inspection is calculated based on the height hp of the object to be inspected P. By default, the reference height hc is calculated by the following equation [2].

[0080] hc = hp / 2 ···[2] Furthermore, the detection data output unit 31, which has a delay time calculation function, calculates a delay time t1 corresponding to the reference height hc for which inspection is desired, based on the calculation result of the reference height hc, the arrangement of the multiple stages of detection element arrays 22a and 22b of the X-ray generator 21 and X-ray detector 22, and the transport speed V of the item transport unit 10 according to the type of item P to be inspected.

[0081] During inspection, the control function of the control unit 30 activates the item transport unit 10, transporting the object to be inspected P at a predetermined transport speed V. At the same time, as the object to be inspected P passes through the inspection area Z1, X-rays are irradiated from the X-ray generator 21 at a preset irradiation intensity according to the type of object, and the X-rays that pass through the object to be inspected P are detected by the X-ray detector 22.

[0082] During this inspection, the control unit 30 first temporarily stores the detection data Lxa and Lxb from the multi-stage detection element arrays 22a and 22b output from the X-ray detector 22 in the working memory of the detection data output unit 31. Then, using the calculated delay time t1, a synthesis process is performed by integrating the detection data Lxa and Lxb in the TDI method so that the detection timing of the object P under inspection by two adjacent stages (any two stages before and after) of detection element arrays 22a and 22b is matched between each pair of X-ray detection elements adjacent to each other in the direction of item transport, thereby obtaining detection data Lx corresponding to the reference height hc.

[0083] In this embodiment, the optical image emitted from the scintillator 22s of the X-ray detector 22, which has good afterglow characteristics for detecting X-rays, is photoelectrically converted by a CMOS-type photoelectric sensor to obtain detection data Lxa and Lxb from multiple stages of detection element arrays 22a and 22b (line sensors) of the X-ray detector 22. These detection data Lxa and Lxb are then integrated using the TDI method to obtain imaging data Lx, and an inspection image Dpx is generated based on this imaging data Lx.

[0084] In generating this inspection image Dpx, a predetermined amount of light emission is obtained within a time of 1 / 2 or 1 / k (where k is a natural number) of the delay time t1, which is the scanning period of each stage of the X-ray detector 22. Furthermore, the scintillator 22s, which has good afterglow characteristics and short afterglow characteristics so that the afterglow does not overlap with the detection signal of the next period of each stage of the detection element array 22i, effectively suppresses blurring of the inspection image obtained from imaging data of multiple stages of detection element arrays 22a and 22b.

[0085] Therefore, by employing a CMOS sensor and using the TDI method, inspection images are generated with low noise even in high transport speed ranges. In addition, the improvement in the temporal resolution of scintillation light effectively suppresses blurring of the X-ray image Dpx, ensuring the required detection sensitivity.

[0086] Then, based on the image data of the inspection image Dpx for which the required detection sensitivity has been ensured, a predetermined inspection process is performed in the inspection processing unit 35, and after that, the determination process for X-ray inspection is performed in the determination unit 36.

[0087] In this embodiment, the variety control unit 33 and the degradation detection unit 37 also detect when specific inspection conditions that degrade the image quality of the inspection image Dpx are met. When this is detected, the detection data Lx output from the detection data output unit 31 is adjusted by the level conversion processing unit 32 to improve the image quality of the inspection image Dpx. As a result, the image generation unit 34 can generate an inspection image Dpx with an expanded range of density values, and the inspection processing unit 35 can perform accurate inspection processing based on the data of the inspection image Dpx with an expanded range of density values.

[0088] In other words, by expanding the range of density values ​​of the inspection image Dpx through binning or kernel processing, image reduction can be achieved while suppressing information loss due to pixel decimation. This allows for more effective suppression of the effects of a decrease in the signal level of the X-ray detection signal, even when the item transport speed V is increased or the output of the X-ray generator 21 is reduced, enabling high-quality inspection processing.

[0089] Furthermore, in this embodiment, the specific inspection conditions include the condition that the transport speed V of the object to be inspected P passing through a predetermined section on the transport path 11a reaches a predetermined speed or higher, or that the irradiation intensity of the X-rays irradiated onto the object to be inspected P from the X-ray generator 21 has decreased to below a predetermined intensity. Therefore, when the specific inspection conditions that degrade the image quality of the inspection image Dpx are met, the detection data Lxa and Lxb output from the X-ray detector 22 are adjusted by the level conversion processing unit 32 in addition to the TDI method imaging data processing to improve the image quality of the inspection image Dpx. Thus, the required image quality of the inspection image DPx is ensured, and a good inspection process can be performed.

[0090] Furthermore, in this embodiment, the scan period in the main scanning direction of the X-ray detector 22 and the delay time t1 for the integration processing of the TDI method are variably set so that the aspect ratio on the transmitted image at the reference height hc becomes 1. Therefore, the resolution in the X and Y directions, which are the coordinate axes of the two-dimensional inspection image Dpx, is obtained uniformly, and the effect of the time delay integration of the TDI method is accurately obtained.

[0091] In this embodiment, by configuring the system to store a reference height hc set by the height setting means for each variety, a suitable reference height hc, such as the height center or the center of gravity height, can be set for each variety, and the time it takes for each part of the planar cross-sectional region A of that reference height hc to pass between the adjacent detection element row 22a on the front side and detection element row 22b on the rear side in the transport direction can be set to a suitable height as the transport direction delay time t1 for the TDI method's integration processing.

[0092] Furthermore, in this embodiment, a warning output can be provided when transport disturbances occur in the high-speed transport region that lead to a decrease in the image quality of the inspection image Dpx, for example, due to the influence of lead-filled curtains C1 and C2 on the inlet and outlet sides. In this case, as a means of detecting transport disturbances, the width of the workpiece in the transport direction on the transmitted image, i.e., the length of the object to be inspected P in the X direction, can be measured, or transport vibrations and corresponding changes in transport load can be monitored based on the output pulse of the encoder E of the transport motor M or based on changes in the current of the motor M.

[0093] In addition, in this embodiment, it is also conceivable to increase the tube voltage of the X-ray tube 21a of the X-ray generator 21 compared to that in the normal transport speed range in order to suppress dose deficiency in the high-speed transport range. Needless to say, such transport speed and tube voltage of the X-ray tube can be variably set according to the type of object P to be inspected.

[0094] According to this embodiment, it is possible to provide an X-ray inspection apparatus that can perform good inspections while increasing the speed of item transport and reducing the output of the X-ray generator, while ensuring the required detection sensitivity in the TDI type X-ray detector.

[0095] In this description, the X-ray detector 22 is explained as multiple line sensors consisting of multiple stages of detection element arrays 22a, 22b, etc. However, the X-ray detector 22 may also be a CMOS sensor type area sensor configured with multiple stages of detection element arrays 22a, 22b, etc., and imaging data processing may be performed in which detection data from multiple stages of detection element arrays 22a, 22b, etc. that move forward and backward in the transport direction are integrated using the TDI method.

[0096] As described above, the X-ray inspection apparatus of the present invention achieves high-speed material transport and low-power X-ray generator while effectively suppressing the effects of a decrease in the detection signal level of a line sensor type X-ray detector in high transport speed regions and other specific inspection conditions, thereby enabling good inspection. The present invention is useful for X-ray inspection apparatuses in general that acquire image data corresponding to the dose distribution of X-rays transmitted through a transported material by the periodic detection operation of a line sensor type X-ray detector, and inspect the quality of the object being inspected based on that image data. [Explanation of Symbols]

[0097] 1. X-ray inspection device 10. Goods transport section 11 belts 11a Conveyor path 12, 13 Laura 20 X-ray Examination Department 21 X-ray generator 21a x-ray tube 21b Box body 21c X-ray window 22 X-ray detector (line sensor) 22a, 22b Detection element array (multi-stage detection element array, multi-stage line sensor, CMOS type photoelectric sensor) 22c, 22d Detection element array (multi-stage detection element array, multi-stage line sensor, CMOS type photoelectric sensor) 22i Detection element array for each stage (line sensors and CMOS type photoelectric sensors for each stage) 22s scintillator 30 Control Unit 31 Detection data output unit (TDI method imaging data processing unit) 32 Level conversion processing unit (image data adjustment means) 33 Variety Control Unit 34 Image generation unit 35. Inspection Processing Unit 36 Judgment section 37. Deterioration detection unit (inspection condition detection means) 38 Condition setting unit (height setting means, scanning condition setting means) 38a Memory (storage means) 40 Display operation unit (height setting means, scanning condition setting means) C1, C2 Curtains (Lead-filled blackout curtains) Dpx examination image (image data of the examination image) e1~e N Multiple X-ray detection elements (detection elements) Lx detection data (TDI-combined detection data, light-receiving data) Lxa, Lxb detection data P Test object S1a, S1b, S1c, S1d subsegment area Sim1 segment image (segment image before binning) Sim2 segment image (segment image after binning; data from the examination image with an expanded range of density values) t1 delay time t2 Scan period (scan period of the line sensor) X transport direction (X direction, sub-scanning direction) Y Main scanning direction (Y direction, transport path width direction) Z1 Inspection area (predetermined section) Z2 enclosure installation area (xi, yj) Pixel (coordinate components of the pixel)

Claims

1. An X-ray generator (21) irradiates an object (P) to be inspected as it passes through a transport path (11a) with X-rays, Multiple detection elements (e １ ~e Ｎ An X-ray detector (22) has multiple stages of detection element arrays consisting of the above in the transport direction, and outputs detection data obtained from each detection element for each stage of the multiple stages of detection element arrays, An X-ray inspection apparatus comprising: an inspection processing unit (35) that generates an inspection image (Dpx) consisting of a plurality of pixels (xi, yj) having respective density values ​​based on detection data output by the X-ray detector, and inspects the quality of the object to be inspected based on the inspection image, The X-ray detector comprises a scintillator (22s) with good afterglow characteristics for detecting X-rays, and CMOS-type photoelectric sensors (22a, 22b; 22a, 22b, 22c, 22d) that receive light emitted in response to the X-rays detected by the scintillator and output detection data (Lxa, Lxb). The X-ray inspection apparatus is characterized in that it generates the inspection image using light-receiving data (Lx) obtained by integrating the detection data of the multiple stages of detection element arrays using the TDI method.

2. An inspection condition detection means (37) for detecting when specific inspection conditions that degrade the image quality of the aforementioned inspection image are met, When the inspection condition detection means detects that the specific inspection condition has been met, the system includes an image data adjustment means (32) that adjusts the detected data output from the X-ray detector to improve the image quality of the inspection image. The X-ray inspection apparatus according to claim 1, characterized in that it generates an inspection image with an expanded range of density values ​​based on the adjusted detection data adjusted by the image data adjustment means, and the inspection processing unit performs the inspection process based on the data of the inspection image with an expanded range of density values.

3. The X-ray inspection apparatus according to claim 2, characterized in that the specific inspection conditions include the condition that the transport speed of the object to be inspected passing through a predetermined section on the transport path reaches a predetermined speed or higher, or that the irradiation intensity of the X-rays irradiated onto the object to be inspected from the X-ray generator has decreased to below a predetermined intensity.

4. Height setting means (38, 40) for setting a reference height from the conveying surface of the conveying path, The X-ray inspection apparatus according to claim 1 or 2, characterized by comprising scanning condition setting means (38, 40) for setting the scan period (t2) in the main scanning direction and the delay time (t1) in the transport direction of the X-ray detector so that the aspect ratio on the transmitted image at a reference height is 1.

5. The X-ray inspection apparatus according to claim 4, further comprising a storage means (38a) for storing a reference height set by the height setting means for each variety.

Images