JP4127698B2 - X-ray inspection equipment - Google Patents

Description

  The present invention relates to an X-ray inspection apparatus, and in particular, irradiates a workpiece (object to be measured) being conveyed with X-rays and performs volume measurement or mass measurement based on the X-ray transmission amount, or further detects foreign matter. The present invention relates to an X-ray inspection apparatus suitable for performing the above.

  The article that is the object to be inspected is caused to travel at a constant speed by the conveyance belt, and the accumulated transmission amount of the X-rays irradiated to the workpiece being conveyed is sampled by the X-ray detector to create an X-ray image. Such an X-ray inspection apparatus is known.

  As a conventional X-ray inspection apparatus of this type, Patent Document 1 (US Pat. No. 6,215,845) discloses that an X-ray irradiation means irradiates a test object package with a fan-shaped X-ray beam. X-rays that have passed through the package are detected by an X-ray detector in which a plurality of X-ray detectors are arranged in an array, and missing parts are detected by combining mass signals from the plurality of X-ray detectors. Is described.

  In Patent Document 2 (US Pat. No. 6,347,131), a plurality of products are continuously conveyed by a conveyor belt, and pass through an X-ray irradiation region irradiated with a beam from a radiation source in the middle of the conveyance. On the other hand, the X-ray transmitted through the product is detected by a fluorescent plate and a photodiode array below the conveyor belt, and the volume of the product is measured by corresponding to the thickness of each part of the product. Yes.

  In Patent Document 3 (US Pat. No. 5,585,603), an article is positioned at an inspection position near an X-ray source and irradiated with X-rays, and an X-ray transmission region of the article is divided into a plurality of volumes. It is divided into elements, the mass is obtained from the average density and volume of each volume element region, and the mass of all volume elements is added to weigh the article.

  Furthermore, in Patent Document 4 (US Pat. No. 6,385,284), a flexible meat processed product is transported as an inspection object, and X-rays are irradiated from a lower X-ray source to a chamber in the pipe. Then, the transmission X-ray is detected by an X-ray sensor to detect the physical property of the inspection object.

US Pat. No. 6,215,845 US Pat. No. 6,347,131 US Pat. No. 5,585,603 US Pat. No. 6,385,284

  However, in the conventional X-ray inspection apparatus as described above, even if the sensitivity characteristics of the main components such as the X-ray source and the X-ray detector are in a stable operation state, they drift due to environmental temperature changes and the like. Furthermore, the measured values were likely to vary due to aging of the main parts. That is, such temperature drift and aging change have had a great influence on measurement accuracy. For this reason, it is necessary to periodically stop the operation of the X-ray inspection apparatus in a relatively short period in order to suppress variations in measurement accuracy, and to correct the output of the X-ray source and the detection sensitivity of the X-ray detector. It was. Specifically, as described in Patent Document 2, for example, a test block made of a material having an X-ray transmittance equivalent to that of the inspection object is prepared, and based on the X-ray transmission amount data for the test block, Correction work for adjusting the sensitivity of each detection element portion of the X-ray detector is necessary.

  Therefore, in the conventional X-ray inspection apparatus, since the operation of the X-ray inspection apparatus needs to be stopped for a relatively long time every correction work, the operation rate of the apparatus decreases, or temperature drift, etc. There was a problem that the measurement accuracy was forced to vary.

  The present invention has been made in view of the problems of the prior art, and by making it possible to correct the zero point while inspecting the workpiece, it is possible to reduce variations in accuracy due to temperature drift and the like, and to An object of the present invention is to provide an X-ray inspection apparatus capable of measuring the volume and mass of a workpiece with high accuracy by devising the processing.

To achieve the above object, the present invention provides (1) a transport path for transporting a work, an X-ray source for irradiating the work being transported with X-rays in a predetermined inspection space, and the transport in the inspection space. An X-ray detector capable of detecting X-rays transmitted through the work for each of a plurality of transmission regions adjacent in a direction orthogonal to the direction, and the work transmitted through the work based on detection information of the X-ray detector A processing unit for processing data corresponding to the transmission amount of each X-ray transmission region to generate a digital X-ray image, and measuring the volume of the workpiece based on the X-ray image The processing unit sets a background density value in the X-ray image, a foreground representative density in the X-ray image, a maximum density of the equivalent thickness image, and a correction index value, respectively. By the following formula [1]
By calculating density data of the equivalent thickness image, conversion processing from density data of the X-ray image in each transmission region to density data of an equivalent thickness image corresponding to the thickness of the workpiece in each of the transmission regions is performed. Data conversion processing means to be applied; volume measuring means for measuring the volume of the workpiece in the plurality of transmission areas based on density data of the equivalent thickness image corresponding to each of the plurality of transmission areas; and the amount of X-ray transmission A zero point correction unit that processes the corresponding data and zero-corrects the density data of the X-ray image so that the equivalent thickness of the background when the X-ray is irradiated to the workpiece is zero. The data conversion processing means converts the linearity of the density data of the equivalent thickness image corresponding to the thickness of the workpiece within a predetermined range set according to the workpiece to the X-ray of the X-ray source. Injection force and the said linearity above formula so as to obtain the density data of the equivalent thickness image to the thickness of the workpiece in the transmittable regions of the non-defective work of the workpiece to be inspected in accordance with the material of the work [1 ], The linearity correction unit corrects the correction index value by adjusting the adjustment index value, and the zero point correction unit adjusts the linearity by the linearity correction unit according to the cycle of measuring the volume of the workpiece. The zero point correction is performed based on the corrected density data.

With this configuration, zero point correction is repeatedly executed at an appropriate cycle according to the workpiece volume measurement cycle, and real-time zero point correction can be performed while inspecting the workpiece. Therefore, variation factors such as temperature drift are removed by zero point correction, and variations in volume measurement accuracy due to temperature drift and the like are prevented. Note that the background here refers to a portion of the X-ray image corresponding to, for example, the work placement surface of the transport belt. In addition, with this configuration, the linearity of the equivalent thickness concentration value with respect to the thickness of the workpiece can be secured, and coupled with the fact that the zero point correction is always performed, the X-ray detector can be applied to the equivalent thickness image due to ambient temperature changes. Effects such as temperature drift are eliminated without detecting the ambient temperature.
The density data of the equivalent thickness image changes within the range of the maximum density value Qmax of the equivalent thickness image according to the ratio of the density value P1 of the foreground in the X-ray image and the density value P of the X-ray image in each transmission region. Therefore, it is possible to suppress variations in measurement accuracy due to zero point drift of the X-ray detector. Further, by performing correction to increase or decrease the correction index value γ according to the X-ray irradiation output of the X-ray source or the material of the workpiece, the linearity of the density data of the equivalent thickness image with respect to the thickness of the workpiece can be secured, Combined with the constant zero point correction, the influence of the temperature drift of the X-ray detector on the equivalent thickness image due to the ambient temperature change is eliminated without detecting the ambient temperature.

  The X-ray inspection apparatus according to the present invention further includes (2) a conversion unit that converts the volume measurement value for each of the transmission regions measured by the volume measurement unit into a conversion value in mass unit at a preset conversion ratio. It can be provided. With this configuration, the workpiece mass can be measured, and zero point correction is repeatedly executed at an appropriate cycle according to the measurement cycle. Therefore, variation factors such as temperature drift are removed by zero point correction, and variations in mass measurement accuracy due to temperature drift and the like are prevented.

When performing the conversion process according to the equation [1], ( 3 ) the data conversion processing unit corrects the density data of the equivalent thickness image within a range where the correction index value is 1.3 ± 0.2. It is more preferable to carry out. Thereby, when performing X-ray inspection using many foods as workpieces, good linearity of the equivalent thickness image density value Q (P) can be secured.

In the X-ray inspection apparatus of the present invention, more preferably, ( 4 ) the data conversion processing means is based on a density value of an X-ray image in a specific transmission region of a representative work serving as a standard of the work. The density value Q (Pa) of the equivalent thickness image calculated in [1] is set as the value of Qa expressed by the following equation [2], and the calculated density value Q (Pa) of the equivalent thickness image and the specific workpiece are specified. Using the density value Pa of the X-ray image in the transmission region, the density value P2 in the formula [2], which is the representative density value of the foreground in the X-ray image of the representative workpiece, is calculated in advance.

In terms of replacing the representative density value P ₁ of the foreground in the X-ray image to the density value P ₂ of the calculated and has a density corresponding to the thickness of the workpiece from the density data P of X-ray images in each transmission region Conversion processing of equivalent thickness images into density data Q (P) is executed.

With this configuration, in the concentration range of sizes preferred concentration corresponding to the detection permeation amount equivalent concentration values P for the foreground representative density setpoint P ₁ in the X-ray image to the maximum density setting value Qmax of the equivalent thickness image density, The density of the equivalent thickness image is set in combination with the adjustment of the correction index value according to the irradiation output of the X-ray source and the work. The data Q (P) can exhibit an automatic gain control function that is not affected by the type of workpiece.

In the X-ray inspection apparatus according to the present invention, ( 5 ) the zero point correction unit may include the second of the first area where the work is placed on the transport path and the second area where the work is not placed. Detecting a transmission amount of X-rays transmitted through the conveyance path for a plurality of transmission regions spaced apart from each other in the region, and based on the X-ray transmission amounts of the transmission regions spaced apart from each other in the second region, It is preferable to perform zero point correction. In this case, ( 6 ) a plurality of transmission regions separated from each other in the second region may be separated from both ends in the width direction of the conveyance path in the inspection space. As a result, the zero point correction can be executed in real time at an arbitrary cycle.

Further, ( 7 ) a predetermined placement width range of the workpiece on the conveyance path based on an amount of X-rays transmitted through the conveyance path in the plurality of transmission regions spaced from both ends in the width direction of the conveyance path. It is also possible to provide a protrusion detection means for detecting protrusion from the outside. In this way, the transmission amount detection information for zero point correction can be used as information for detecting the protrusion from the predetermined placement width range of the workpiece, and a protrusion detection means with a simple configuration can be realized.

( 8 ) Based on the transmission amount of the X-rays transmitted through the plurality of transmission regions spaced at both ends in the width direction of the transport path, the width direction end portions of the transport path corresponding to both transmission amount values. By determining the density value of the X-ray image and setting an offset density that linearly connects the density values of the X-ray images at both ends, the inclination correction for the transmission amount data of the plurality of transmission regions is performed at the zero point. It is desirable to execute with correction. With this configuration, by subtracting the offset density from the density data P of the X-ray image, tilt correction (e.g., equivalent to correction for canceling the background gradation in the X-ray image that is the conveyor belt surface) and zero point drift are achieved. It becomes possible to correct.

In the X-ray inspection apparatus of the present invention, ( 9 ) the zero point correction unit includes a conveyance interval detection unit that specifies a conveyance interval of the workpiece on the conveyance path, and is based on detection information of the conveyance interval detection unit. The second area may be specified as a range corresponding to the conveyance interval. In this way, in cases other than continuous workpieces such as loose objects, the X-ray transmission amounts of the plurality of transmission regions in the entire width direction of the transfer path are checked using the non-transfer section between the individual works on the transfer path. Therefore, it is possible to judge the effectiveness of fine zero point correction and inclination correction.

In the X-ray inspection apparatus of the present invention, ( 10 ) a volume measurement value table in which a reference volume measurement value for a reference workpiece for setting measurement sensitivity is associated with a predetermined detection parameter that affects the measurement sensitivity; A sensitivity information storage unit that stores a sensitivity correction coefficient that corrects the sensitivity of volume measurement, specifies the predetermined detection parameter for each volume measurement of the reference workpiece, and stores the volume measurement stored in the sensitivity information storage unit Sensitivity correction means for updating the sensitivity correction coefficient based on the value table, the latest volume measurement value of the reference workpiece and the predetermined detection parameter at the time of measurement, and maintaining the sensitivity of the volume measurement within a certain range Is further provided. With this configuration, the sensitivity correction coefficient is appropriately updated based on the reference volume measurement value of the reference work and the volume measurement value at the time of measurement, and the detection sensitivity drift due to the ambient temperature and secular change can be calibrated with high accuracy. .

In the case of including sensitivity correction means, ( 11 ) when the predetermined detection parameter includes at least a voltage value for driving the X-ray source, and the volume of the reference workpiece is measured, the sensitivity correction means is The sensitivity correction coefficient is updated based on a ratio between the measured latest volume measurement value and the volume measurement value in the volume measurement value table stored in the sensitivity information storage unit. Is preferred.

With this configuration, for example, a volume measurement value V ₁ (E) of the standard workpiece is obtained by creating a reference table of the volume measurement value V ₀ (E) of the standard workpiece that changes according to the tube voltage E of the X-ray source. At that time, the sensitivity correction coefficient β is updated to β = V ₀ (E) / V ₁ (E), so that the temperature drift of the detection sensitivity can be calibrated accurately and easily.

In the X-ray inspection apparatus of the present invention, ( 12 ) the volume measuring means uses the density data that exceeds a predetermined noise cut threshold among the density data of the X-ray image in each transmission region. It is better to execute. Thereby, the stability improvement of volume measurement can be expected in many cases.

In the X-ray inspection apparatus of the present invention, ( 13 ) the conversion value of the volume measurement value for each transmission region converted into the value of the mass unit by the conversion means is within a predetermined mass allowable range corresponding to the workpiece. There may be provided mass acceptance / rejection determination means for determining whether or not the mass measurement result is acceptable depending on whether or not there is. Thereby, the pass / fail information of the mass measurement result for each workpiece can be obtained.

In the X-ray inspection apparatus of the present invention, ( 14 ) when the workpiece includes a tare, the volume measuring means calculates the volume measurement value of the entire workpiece calculated based on the density data of the equivalent thickness image of the workpiece. The taring process for subtracting the volume value corresponding to the tare can be executed. In this way, even when the work includes a tare, the mass of the tared content can be directly output.

Alternatively, ( 15 ) when the workpiece includes a tare, the volume measuring means stores in advance a conversion ratio between the mass and the volume of the tare, and when the mass of the tare is set, The tare subtraction process may be executed by subtracting the volume value of the tare from the volume measurement value of the entire workpiece calculated based on the density data of the equivalent thickness image of the workpiece after conversion into the volume. With this configuration, it is possible to execute a tare subtraction process based on an input for specifying a tare mass value.

The X-ray inspection apparatus of the present invention further comprises ( 16 ) a foreign matter detection means for detecting the foreign matter by determining the presence or absence of the foreign matter in the workpiece based on the detection information of the X-ray detector. It may be. With this configuration, not only volume or mass measurement but also foreign object detection can be performed, and variation factors such as temperature drift of the X-ray detector are eliminated by zero point correction, and mass measurement due to temperature drift, secular change, etc. Variation in accuracy and variation in foreign matter detection accuracy can be suppressed.

In the X-ray inspection apparatus that performs the foreign object detection, ( 17 ) the processing unit detects the foreign object from the data corresponding to the X-ray transmission amount when the foreign object is detected according to the detection result of the foreign object detection means. It is desirable to remove the data that has passed through the foreign material and to perform a process of interpolating the removed data based on the transmission amount data in a region around the region that has passed through the foreign material. Thereby, a mass measurement result can always be obtained independently of foreign object detection.

When mass conversion is performed by performing conversion to the mass, ( 18 ) display according to the mass measurement value of the workpiece having a mass indicator unit that changes a display range according to the mass measurement value of the workpiece. It is desirable to have a display means having a mass indicator section for changing the range. Thereby, the measured mass can be immediately recognized from the display range of the mass indicator section.

  According to the present invention, zero point correction is performed at an appropriate cycle according to the workpiece volume measurement cycle, thereby enabling real-time zero point correction while inspecting the workpiece. It is possible to provide an X-ray inspection apparatus capable of removing factors by zero point correction and preventing variation in measurement accuracy due to temperature drift or the like.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[First embodiment]

  FIGS. 1-12 is a figure which shows 1st Embodiment of the X-ray inspection apparatus which concerns on this invention, and has shown the example which applied this invention to the mass measuring apparatus which measures volume and mass.

  First, the configuration will be described.

  As shown in FIGS. 1 and 2, the X-ray inspection apparatus of the present embodiment emits X-rays within a predetermined inspection space to a conveyance path 1 composed of a belt conveyor that conveys a workpiece W and the workpiece W being conveyed. An X-ray source 2 to be irradiated, an entry detection sensor 3 comprising, for example, a light projecting / receiving device for detecting the entry of the workpiece W into the inspection space, and a direction orthogonal to the conveyance direction in the inspection space (hereinafter referred to as the conveyance path width direction). X-ray detector 4 capable of detecting X-rays transmitted through the workpiece W for each of a plurality of transmission regions adjacent to each other, and X-rays transmitted through the workpiece W based on detection information of the X-ray detector 4 An image input unit 5 that generates density data (hereinafter referred to as X-ray image density data) P corresponding to the accumulated transmission amount at each predetermined time in each transmission region, and every predetermined time of each transmission region from the image input unit 5 X-ray image density data Includes a processing unit 6 to generate a digital X-ray image, a by executing the image processing that associates P pixel data.

  The conveyance path 1 conveys, for example, a workpiece W of an individual (which may be a regular or flexible irregular shape) to be a food or a medicine at a predetermined constant conveyance speed corresponding to the type, and in the middle of the conveyance. The work W is passed between the X-ray source 2 and the X-ray detector 4 through the predetermined inspection space in the apparatus housing (not shown).

  The X-ray source 2 has an X-ray tube that generates X-rays by colliding a thermoelectron from a cathode filament with an anode target by a high voltage between the cathode and the anode, for example. The X-ray detector 4 is shaped and irradiated into a fan-shaped beam B (see FIG. 2) that spreads in the width direction of the transport path 1 by a slit (not shown). That is, the X-ray source 2 and the X-ray detector 4 constitute a so-called X-ray fan beam optical system.

  In addition, the X-ray detector 4 is configured by arranging detection elements composed of a scintillator that is a phosphor and a photodiode or a charge-coupled element in an array shape in the width direction of the transport path 1 at a predetermined pitch so that X with a predetermined resolution is obtained. It is composed of an X-ray line sensor camera adapted to perform line detection.

  The conveyance path 1 and the X-ray source 2 are controlled to operate at predetermined timings by a conveyance and X-ray irradiation control unit (not shown).

  The image input unit 5 performs, for example, A / D conversion of transmission amount detection signals from a plurality of detection elements of the X-ray detector 4, and a predetermined unit corresponding to the arrangement pitch of the detection elements in the X-ray detector 4. Data on accumulated transmitted X-ray dose (hereinafter simply referred to as transmitted amount) within the unit time for all the transmission regions n (n is an integer greater than 1, for example, 640) shown in FIG. For example, an operation (hereinafter, referred to as line scanning) is written in the data storage unit 5a as digital data having a density level representing gradations from 0 to 1023.

  Further, the image input unit 5 adjusts the detection sensitivity of the X-ray detector 4 so that the X-ray transmission amount of each transmission region only on the belt surface becomes equal when the work W is not on the conveyance path 1. The control unit (not shown) is included.

  Further, the image input unit 5 repeats the line scanning for a preset number of times, thereby generating transmission amount data written in the data storage unit 5a as density data P of the X-ray image and outputting it to the processing unit 6. A data processing program and a working memory (not shown).

  The processing unit 6 can read out a control program for performing each function of a plurality of processing function units described later in cooperation with the ROM, for example, a microcomputer (not shown) having a CPU, ROM, RAM and I / O interface. The auxiliary storage device stored in the memory and the timer circuit etc. are configured, and according to the control program stored in the ROM etc., the CPU executes predetermined arithmetic processing while exchanging data with the RAM etc. The control program is executed.

  As shown in FIG. 1, the processing unit 6 includes a zero point correction unit 61, a conversion processing unit 62, a volume measuring unit 63, a mass conversion unit 66, and a protrusion detection unit 69 as the plurality of processing function units. It consists of

  The zero point correction unit 61 has a zero point correction program for executing a zero point correction process, which will be described later, and a work memory area for the zero point correction process according to the cycle of measuring the volume of the workpiece W, and density data of the X-ray image. The background when the workpiece W is irradiated with X-rays, and the density data P of the X-ray image is set so that the equivalent thickness of the transport belt on which the workpiece W is placed is zero in this embodiment. The zero point is corrected.

  The conversion processing unit 62 converts the density data P of the X-ray image in each transmission region into density data Q (P) of an equivalent thickness image corresponding to the workpiece thickness t in each transmission region (details will be described later). Data conversion processing means, and a conversion processing program and a working memory area for this purpose.

  The density data Q (P) of the equivalent thickness image here is a density value obtained by logarithmically converting the density data P of the X-ray image according to a conversion formula described later so as to correspond to the X-ray absorption amount, and there is no inspection object. The minimum density value is obtained when the value of the X-ray transmission amount is maximum and the X-ray absorption amount by the inspection object is zero, and the maximum concentration is obtained when the value of the X-ray transmission amount is minimum and the X-ray absorption amount is maximum. Become.

  In general, the density of an image obtained by logarithmically converting an X-ray image (density data P for each pixel) is determined when parameters on an inspection system such as an X-ray tube, an X-ray optical system, an X-ray detector, and a conveyor belt can be regarded as constant. X-ray energy distribution that changes according to the tube voltage of the X-ray tube, X-ray radiation amount that changes according to the tube current, and distribution of X-ray absorption spectrum that changes according to the type and density of the component atoms of the workpiece And the thickness distribution on the workpiece W.

Physically, N ₀ photons of a predetermined energy pass through the workpiece (thickness t, linear absorption coefficient α) and the transport belt (thickness t ₀ , linear absorption coefficient α ₀ ), thereby becoming N pieces. The decreasing phenomenon can be approximated by the following equation [11] according to Lambert-Beer's Law.

In the X-ray fan beam optical system employed in the present embodiment, for example, the received light amount for each pixel in the range of the focal elevation angle (90 ° −θ) of the X-ray detector 4 composed of a scintillator type CCD line sensor. I is a value I (θ) = {1 / (1 + tan ² θ)} · I (0 °) corresponding to the X-ray irradiation intensity in each transmission region. Light reception sensitivity correction is performed by adjusting the detection sensitivity of the X-ray detector 4 so that the light reception amount I (θ) has a flat light reception amount characteristic.

Accordingly, the received light amount I ₀ before the workpiece W is transported after the correction of the light receiving sensitivity becomes a constant value substantially corresponding to N ₀ exp (−α ₀ · t ₀ ), and the angle θ is obtained by correcting the light receiving sensitivity of the X-ray detector 4. The amount of received light I ′ that is no longer dependent on can be considered as I ′ = I ₀ exp (−α · t).

  Here, α · t is a value that directly indicates the amount of X-ray absorption by the substance that has passed through the X-ray from the source until it is detected by the X-ray measurement unit, and this is the value of the X-ray absorption image. By associating with the density value, an image having a larger density value can be created for a substance having a higher X-ray absorption rate or a thicker part in the X-ray transmission direction.

Therefore, when the received light amounts I ′ and I ₀ are used and α · t is an equivalent thickness τ in each transmission region of the workpiece, and a value J (τ) obtained by multiplying the equivalent thickness τ of the workpiece W by γ, this J (τ τ) can be expressed by the following equation [12].

  From the above theoretical considerations, the correction index value γ may be 1. However, as a result of experiments, if the correction index value γ is within a certain range close to 1.3, the thickness t is set to the thickness t for many foods. On the other hand, it was found that J (τ) shows good linearity.

  Based on such experimental results, the data conversion processing unit 62 adjusts the correction index value γ within a predetermined range set according to the work W, and the density of the equivalent thickness image corresponding to the thickness t of the work W A linearity correction unit 62a that corrects the linearity of the data is provided.

Specifically, the zero point correction unit 61 and the data conversion processing unit 62 determine the background density value P ₀ in the X-ray image, the foreground representative density P ₁ in the X-ray image, and the maximum density Qmax in the equivalent thickness image. Is set and inputted, and based on the set value, the conversion process to the density data Q (P) of the equivalent thickness image in each transmission region of the workpiece W is executed by the following equation [1]. It has become.

Here, the density data Q (P) of the equivalent thickness image is a value after logarithmic conversion corresponding to the density J (τ) of the distribution image of the equivalent thickness τ described above, and is further subjected to zero point correction ( Q (P ₀ ) = 0), which also has a zero point correction function.

  Further, the correction index value γ is adjusted in a certain range close to 1.3, for example, within a range of 1.3 ± 0.2. By performing correction to adjust the correction index value γ within this range, even if X-ray inspection is performed using many foods as the work W, the density data of the equivalent thickness image with respect to the thickness t of the work W in each transmission region Good linearity of Q (P) can be secured.

Further, the data conversion processing unit 62 calculates the density value Q (of the equivalent thickness image calculated by the above equation [1] based on the density value Pa of the X-ray image in the specific transmission region of the representative work serving as the standard of the work W. Pa) is the value of Qa represented by the following equation [2] (Qa = Q (Pa)), and the calculated density value Q (Pa) of the equivalent thickness image and X-rays in a specific transmission region of the representative workpiece Using the image density value Pa (for example, the X-ray image density of the transmission region corresponding to the maximum thickness), the density value P ₂ in the expression [2], which is the representative density value of the foreground in the X-ray image of the representative workpiece, Pre-calculate the value,

The density value P ₂ calculated here, after performing setting of updating the representative density value P ₁ of the foreground of the formula (1) in the thickness of the workpiece W from the density data P of the X-ray image in the transmittable regions Conversion processing of equivalent thickness images having a density corresponding to the length t to density data Q (P) is executed.

More specifically, the representative workpiece here is a typical non-defective workpiece among the workpieces W to be inspected. The representative workpiece W is once passed through the inspection space, and the concentration value P ₂ in the equation [2] is used. value was calculated, and the calculated value using the equation obtained by substituting the P ₁ in the formula (1), the density data Q of the equivalent thickness image from the density data P of the X-ray image of each workpiece W to be inspected ( Conversion processing to P) is executed.

  The conversion processing unit 62 includes a data lookup table (not shown) that defines conversion conditions, and a processor that performs data conversion processing using the conversion table. The lookup table includes: The density level of the density data Q (P) of the equivalent thickness image, which is the result of the above-described conversion processing, for the density level of the density data P of the X-ray image in a plurality of stages (for example, 1024 gradations from 0 to 1023). Are stored in association with each other.

  The volume measuring unit 63 calculates the volume V of the work W by adding up the density data Q (P) of the equivalent thickness image corresponding to each of the plurality of transmission regions for the entire measurement range of each work W. A process is executed, and a measurement processing program and a working memory area are provided for this purpose.

  Further, as shown in FIG. 5, the volume measuring unit 63 has a density level of density data Q (P) of the equivalent thickness image among a plurality of transmission regions on the scanning line of the X-ray detector 4 as a predetermined noise cut threshold. The volume calculation is performed only for the transmission region as described above, and density data Q (P) (hereinafter referred to as slice) of the equivalent thickness image obtained by each scanning from the front end to the rear end in the conveyance direction of the workpiece W. The volume V of each workpiece W can be calculated by summing only valid data.

The mass conversion unit 66 converts the volume measurement value V for each transmission region measured by the volume measuring means 63 into a conversion value (mass) in mass units at a predetermined conversion ratio (conversion rate) set in advance. It has a processing program, a coefficient holding memory area for storing the mass conversion coefficient λ _W of the workpiece W read from a product parameter file (not shown), and a work memory area for conversion processing.

Here, when the volume measurement value V of a certain workpiece W is multiplied by a mass conversion factor λ _W depending on the type of the workpiece W, the volume measurement value V of the workpiece W can be converted into a value in mass unit. If the value converted into the mass unit is G, the converted value G can be expressed as G = λ _W · V.

  Moreover, the display part 7a is connected to the mass conversion part 66, The mass conversion value of the workpiece | work W converted into the mass unit by the mass conversion part 66, or the volume measurement result of the workpiece | work W before conversion further, respectively. It is output to the display unit 7a.

  The mass conversion unit 66 further includes a program for determining whether or not the mass measurement result is acceptable depending on whether or not the converted value G of the volume measurement value of the workpiece W converted into a mass unit value is within a predetermined mass tolerance range. It is built in as a mass acceptance / rejection determination unit 66a (mass acceptance / rejection determination means), thereby obtaining acceptance / rejection information of the mass measurement result for each workpiece W and outputting it to the display unit 7a together with the mass converted value of the workpiece W. ing.

  On the other hand, the zero point correction unit 61 includes a first area where the workpiece W is placed on the conveyance path 1, for example, a plurality of transmission areas in the width direction central portion 11 of the conveyance path 1 shown in FIG. In the second region that is not placed, for example, among the plurality of transmission regions in the width direction both ends 12a and 12b that are separated from each other in the width direction of the conveyance path 1 shown in FIG. Based on the X-ray image density data P in a plurality of transmission regions separated from each other in the second region, the transmission amount of X-rays transmitted through 1 is detected at a predetermined cycle corresponding to the mass measurement cycle described above. Zero point correction is executed repeatedly.

  This zero point correction will be described. For example, as shown in FIG. 3, during the operation of the X-ray inspection apparatus, if the zero point drift of the X-ray detector 4 does not occur due to, for example, environmental temperature change, On the surface of the conveyor belt, the density level is about the noise level as shown in FIG. 6A. However, when the zero point drift of the X-ray detector 4 occurs, as shown in FIG. The concentration level exceeds the level. On the other hand, in this embodiment, the zero point correction is performed at an earlier stage where the drift amount becomes larger as shown in FIG. 10B, and the noise level is reduced to about the noise level as shown in FIG. Will be maintained.

More specifically, as shown in FIG. 4, the zero point correction unit 61 is based on the transmission amount of X-rays transmitted through a plurality of transmission regions separated from the width direction both ends 12 a and 12 b of the conveyance path 1. The density value Pe ₁ of the X-ray image at the width direction one end 12a of the conveyance path 1 and the density value Pe ₂ of the X-ray image at the width direction other end 12b of the conveyance path 1 are determined (see FIG. 4B). By setting an offset density K that linearly connects the density values Pe ₁ and Pe ₂ of the X-ray images at both ends, inclination correction is performed by subtracting the offset density K from the transmission amount data of a plurality of transmission regions (FIG. 4). (See (c)) is executed together with the zero point correction.

Here, the offset density K that linearly connects the density values Pe ₁ and Pe ₂ of the X-ray images at both ends is the transmission regions d _{2 to} d _{n−1 that are the} measurement points in the middle of the width direction of the transport path _1. offset density values, a density value between the density value Pe _1, Pe ₂ of the opposite end portions, for example, the number of distance L (measurement points corresponding thereto from d _n, smaller than the number n of all the measurement points ) (For example, offset density value K = Pe ₂ + (Pe ₁ −Pe ₂ ) · L / (n−1)). By setting the offset density K, it is possible to cancel the gradation of the background (conveyor belt surface) of the X-ray image.

  The plurality of transmission regions 12a and 12b that are separated from each other in the second region are separated from the widthwise ends 12a and 12b of the conveyance path 1 in the inspection space near the X-ray source, but the workpiece W is parallel. When transported, the second region can be set in the middle of the parallel strip-shaped first regions.

  In the present embodiment, the zero point correction unit 61 further cooperates with the entry detection sensor 3 to convey the workpiece W on the conveyance path 1, that is, the workpiece W is not detected by the entry detection sensor 3, for example, for a certain period of time. A conveyance interval detection unit 61a that identifies the above-described non-conveyance section is included. Based on the detection information of the conveyance interval detection unit 61a, the range of the opened belt surface on the conveyance path 1 corresponding to the conveyance interval is also determined. You may make it identify as 2 area | regions. In such a case, based on this conveyance interval, a plurality of transmission areas in the entire width direction of the conveyance path 1 are utilized using the second area that is a non-mounting area between the individual workpieces W on the conveyance path 1. The density data P of the X-ray image corresponding to the X-ray transmission amount is checked, and the validity judgment is performed on the zero point and the degree of inclination correction of each transmission region corrected by the zero point correction and the inclination correction based on the both ends. It has become. When it is determined that the zero point correction and the inclination correction based on both ends are not functioning effectively as a result of the validity determination, a signal for notifying that the sensitivity adjustment of the X-ray detector 4 is necessary is displayed. It can output to the part 7a and the like.

  Further, in the present embodiment, the protrusion detection unit 69 detects the amount of X-ray transmitted through the conveyance path 1 in a plurality of transmission regions spaced from the width direction both ends 12a and 12b of the conveyance path 1, and the both ends In consideration of the degree of reference zero point correction and inclination correction, whether or not density data P exceeding the predetermined noise level or a slightly larger protrusion limit threshold value is generated in the second area depends on whether or not the conveyance path 1 A predetermined placement width range of the workpiece W on the upper side, for example, a protrusion from the first region is detected. The protrusion detection unit 69 has such a protrusion detection processing program and a working memory area, and a memory area for holding the setting value of the protrusion limit threshold.

  Next, the operation will be described.

  In the above-described X-ray inspection apparatus of the present embodiment, initial settings of measurement conditions such as X-ray irradiation intensity are performed in the following procedure for varieties whose setting parameters are unknown.

First, after setting the tube voltage E and the tube current I specifying the irradiation intensity of the X-ray source 2 to appropriate levels according to the type of the workpiece W, the workpiece W is not placed (hereinafter also referred to as “no conveyance”). ) The detection sensitivity of the X-ray detector 4 is adjusted so that the X-ray transmission amount of each transmission region on the belt surface alone is equal over the entire width direction on the conveyance path 1. Next, the belt surface of the conveyance path 1 at the time of non-conveyance is set as a zero point reference surface for volume measurement, a representative density P ₀ of the belt surface as the background of the X-ray transmission image is set, and the foreground of the X-ray transmission image is set. setting the maximum concentration Qmax of representative density P ₁ equivalent thickness image of the workpiece W is respectively.

Then, if necessary, set a noise cut threshold value, etc., measure the volume of the master work (reference work) with known mass, and calculate from the set master work mass and the measured volume measurement value to set the mass conversion factor λ _W of place. These initial setting data are stored in the memory of the conveyance and X-ray irradiation control unit or the memory in the processing unit 6 and are referred to as appropriate.

Further, these initial measurement data are written in the product type parameter file and read when an input for designating the product type is made.
For the types for which such settings have been made, the measurement control program as shown in the schematic flow in FIGS. 7 to 9 is executed, and when the input for specifying the type of workpiece W to be measured is made, the necessary selection is made. After the operation input, an X-ray inspection is performed.

  The measurement control program shown in FIG. 7 is started when an input for designating the type of workpiece W to be measured is made on a menu screen (not shown). First, each setting parameter set first is read from the type parameter file. Then, when there is an operation input for instructing the start of measurement (step S2), the transfer of the workpiece W by the transfer path 1 is started (step S3).

  Next, when the entry of the workpiece W into the inspection space is detected by the entry detection sensor 3 (step S4), the conveyance section corresponding to the length of the workpiece W from the change in the detection state of the entry detection sensor 3, and the front and rear in the conveyance direction And a non-conveying section corresponding to the interval between the adjacent workpieces W (step S5), and a sampling period during which the X-ray detector 4 performs repeated scanning is determined.

  Next, the protrusion detection unit 69 checks whether or not the density data P of the X-ray image in the transmission region of the widthwise ends 12a and 12b of the conveyance path 1 exceeds the protrusion limit threshold (step S10). When density data P exceeding the second region is generated, it is determined that the protrusion is present (YES in step S6), an error is displayed (step S7), and the conveyance by the conveyance path 1 is stopped (step). S8).

  On the other hand, if it is determined that there is no protrusion (in the case of NO in step S6), then the capturing of the detection signal from the X-ray detector 4 to the image input unit 5 is started at a predetermined timing after the entry detection, The line scanning for each unit transport time is repeated by the length of the workpiece W, and the density level values of n transmission amounts are sequentially stored in the data storage unit 5a of the image input unit 5, while the image input unit 5 The processing unit 6 generates X-ray image density data P as slice data obtained in each scan (step S9).

  Next, the zero point correction unit 61 performs zero point correction and inclination correction of the background of the X-ray image (step S10).

As shown in FIG. 8, this zero point correction processing is performed first on the basis of the density data P of the X-ray image in the transmission region of the width direction both ends 12a, 12b of the transport path 1 in the width direction one end 12a. The density value Pe ₁ of the line image and the density value Pe ₂ of the X-ray image at the width direction other end portion 12b are set as both-end reference values (step S21), and the density values Pe ₁ and Pe of the X-ray images at these both ends are set. ₂ is set (step S21), and by subtracting the offset density K of the area from the density data P for each of the plurality of transmission areas, the belt surface has zero equivalent thickness. The point correction and the tilt correction are executed simultaneously (step S23).

  In addition, when the non-conveyance section reaches a certain time or more, the zero point correction unit 61 identifies the range of the belt surface opened on the conveyance path 1 in the non-conveyance section as the second region, Using the second area, the density data P of the X-ray image in the entire width direction of the transport path 1 is checked (step S25), and each transmission area corrected by the zero point correction and the inclination correction based on the both ends is checked. The effectiveness of the correction is determined by comparing the zero point and the degree of inclination correction with the actually measured values (step S26). As a result of the validity determination, when it is determined that the zero point correction and the inclination correction based on both ends are not functioning effectively (NO in step S26), the sensitivity adjustment of the X-ray detector 4 is necessary. A signal for notifying this is output to the display unit 7a or the like (step S27).

Then, the data conversion processing unit 62, a representative density P ₁ of the foreground in the X-ray image is read and the maximum concentration Qmax of equivalent thickness image, respectively, on the basis of the set value, the equivalent in the transmittable regions of the workpiece W thickness Conversion processing of image density data Q (P) is executed using the above equation [1] (step S11 in FIG. 7).

  At this time, if the correction index value γ has not been adjusted, the linearity of the density data Q (P) of the equivalent thickness image with respect to the thickness t of the workpiece W in each transmission region can be obtained. For example, the correction index value γ is adjusted within a range of 1.3 ± 0.2. This adjustment operation is performed as needed when a typical non-defective workpiece is prepared from the workpieces W to be inspected, and the representative workpiece W is once passed through the inspection space, and is first or once according to an operation input from the setting screen. .

Further, in the foreground of representative density P ₁ is unregulated in the X-ray image, and, if the wafer after being subjected to the adjustment of the correction index value gamma, to perform automatic gain adjustment performed by using the non-defective work prepared operation If the input has been made, the data conversion processing unit 62 calculates the equivalent thickness image calculated by the above equation [1] based on the density value Pa of the X-ray image in the specific transmission region of the representative workpiece as the standard of the workpiece W. Is set as the value of Qa (Qa = Q (Pa)) expressed by the following equation [2], and the calculated density value Q (Pa) of the equivalent thickness image and identification of the representative workpiece are specified. The density value Pa of the X-ray image in the transmissive area of, for example, the X-ray image density of the transmissive area corresponding to the maximum thickness is used to express the representative density value of the foreground in the X-ray image of the representative workpiece in Equation [2] the expression value of the density values P ₂ by [2] Out to. Then, after performing update setting to replace the foreground representative density value the value of the calculated density value P ₂ where the settings for updating the P ₁ of the formula (1) in a concentration of X-ray images in the transmittable regions Conversion processing from data P to density data Q (P) of an equivalent thickness image having a density corresponding to the thickness t of the workpiece W is executed (density conversion processing step S11 shown in FIG. 7).

In this transformation process, as shown in FIG. 9, first, after reading the representative density P ₀ of the background (step S31), the foreground representative density value P ₁ is in the foreground of the representative density values in the X-ray image of a representative workpiece Check whether it is updated set by a certain density value P ₂ value (step S32), if still, to calculate the value of the density value P _2, the foreground representative density value P ₁ to the value Replace (step S33). Then, or if the have already done foreground updates representative density value P ₁ in the above determination step reads the maximum concentration Qmax of equivalent thickness image (step S34), for each transmission area of the workpiece W to be inspected, X Conversion processing from the density data P of the line image to the density data Q (P) of the equivalent thickness image is sequentially executed (step S35).

  Subsequently, the volume measuring unit 63 adds up the density data Q (P) of the equivalent thickness image corresponding to each of the plurality of transmission regions for the entire measurement range of each workpiece W, thereby measuring the volume V of the entire workpiece ( Volume measurement processing step S12 shown in FIG.

  In this volume measurement process, as shown in FIG. 10, first, density data Q (P) of the equivalent thickness image for each transmissive area that has been converted is read (step S41), and the density data Q ( It is checked whether or not the density level of P) is equal to or higher than a predetermined noise cut threshold (step S42), and only for density data Q (P) of an effective transmission region having a density level equal to or higher than this noise cut threshold. Partial volume calculation for each transmission region is executed (step S43). That is, the partial volume v of the transmission region is calculated as the sum of 1 slice data based only on the density data Q (P) indicating the effective equivalent thickness. The calculated partial volume value is stored in a memory area in the volume measuring unit 63 associated with the corresponding transmission area (coordinates) in the workpiece (step S44). Then, after this process is repeated until the required number of scans (for example, m times) is completed (step S45), the entire volume V of one workpiece W, which is the sum of the calculated partial volumes, is calculated ( Step S46).

Next, the volume conversion value G of the work unit W measured by the volume measuring means 63 by the mass conversion unit 66 is converted into a converted value G (G = λ) by a preset mass conversion coefficient λ _W (predetermined conversion ratio). _W · V) and the mass of the workpiece W is measured (mass conversion processing step S13 shown in FIG. 7).

  Subsequently, the mass pass / fail judgment unit 66a of the mass conversion unit 66 further determines whether the mass measurement result is acceptable depending on whether or not the converted value G of the volume measurement value of the work W is within a predetermined mass tolerance range corresponding to the work W. If it is determined that the mass conversion constant value G is within the predetermined mass allowable range (OK in step S15), the pass / failure information of the mass measurement result for each workpiece W and the mass conversion value G of the workpiece W are both displayed on the display unit 7a. It is output (step S16), or the volume measurement result of the workpiece W before mass conversion is further output to the display unit 7a in a display form such as displaying the volume ratio with the representative workpiece. On the other hand, when the mass conversion fixed value G is out of the predetermined mass allowable range (NG in step S15), the conveyance is stopped (step S8). Of course, the NG signal may be output to the work discharging means (not shown) instead of stopping the conveyance.

  For each mass measurement described above, an X-ray equivalent image based on the density data P or an equivalent thickness image based on the density data Q (P) by an image creation unit (not shown) is processed by the processing unit 6. A line absorption image is created, and the digital gray image is displayed on the mass measurement result and the display unit 7a.

FIG. 11 is a diagram illustrating an example of the result of calculating the volume V and calculating the mass as described above together with the equivalent thickness image of the workpiece W. The master work shown in FIG. 5A corresponds to the representative work described above, and is 100 g, for example. In this case, the number of pixels of the gray portion exceeding the density level of the belt surface (equivalent thickness zero) is 75k (about 75000) pixels, and the density level of those equivalent pressure images (in the figure, the i th pixel in the gray scale image). (Tone level Val.i (GrayLvel)), a sum (Sigma) of pixels i = 0 to 75k is calculated, and a volume equivalent value of 8.4 M (M = 10 ⁶ ) is obtained. In the present embodiment, when calculating the mass multiplied by this weight conversion value lambda _W, so that 100g is obtained. Further, in the case of the inspection work shown in FIG. 5B, the number of pixels in the gray portion exceeding the density level of the belt surface (equivalent thickness zero) is 81k (about 81000) pixels, and the pixels for the density level of those equivalent pressure images. By calculating the sum of i = 0 to 81k, a volume equivalent value of 9.6M (M = 10 ⁶ ) is obtained. In this case, the volume ratio with respect to the master work is 1.14, which is 114 g.

  FIG. 12 shows an outline of an example of a screen displayed on the display unit 7a. An image display area 71 for displaying an X-ray image of the workpiece W or an equivalent thickness image is arranged on the left side of the screen in the figure, and a mass distribution or equivalent thickness distribution of a specific X-ray section is displayed on the upper right of the screen. Or the distribution image display part 72 which shows distribution of the mass for the full width in each position of the length direction (left-right direction in a figure) of the workpiece | work W is below the mass display part 73, the display part 74 of the mass acceptance determination result. In addition, a volume ratio display unit 75 is provided. The volume ratio display section 75 displays the volume ratio with respect to the representative workpiece as a percentage (%).

  As described above, in the X-ray inspection apparatus of the present embodiment, zero point correction is repeatedly executed according to the volume measurement period of the workpiece, and real-time zero point correction while inspecting the workpiece becomes possible. . Therefore, variation factors such as temperature drift are removed by the zero point correction, and variations in volume measurement accuracy due to temperature drift, aging, and the like are prevented. In addition, the repetition cycle of the zero point correction is the same as the volume measurement cycle of the workpiece in the above case. However, for example, the zero point correction can be executed every several times of the volume measurement of the workpiece, and an appropriate cycle is set. Can be set.

  Further, in the present embodiment, the mass conversion unit 66 that converts the volume measurement value for each unit transmission region measured by the volume measurement unit 63 into the conversion value of the mass unit at a preset conversion ratio is provided. Since the mass of W can be measured and the zero point correction is repeatedly executed at an appropriate cycle according to the measurement cycle, variations in mass measurement accuracy due to temperature drift, aging, and the like are prevented.

  Further, in the X-ray inspection apparatus according to the present embodiment, the density data Q () of the equivalent thickness image corresponding to the thickness t of the workpiece W is within a predetermined range set by the conversion processing unit 62 according to the type of the workpiece W. Since there is a linearity correction unit 62a that corrects the linearity of P), the linearity of the equivalent thickness concentration data Q (P) can be secured with respect to the thickness t of the workpiece W in each transmission region, and zero point correction is always performed. In combination with this, the influence of the temperature drift of the X-ray detector 4 due to the ambient temperature change is eliminated without detecting the ambient temperature.

Further, the conversion processing unit 62, a foreground representative density P ₁ in the X-ray image, the representative density P ₁ of the foreground in the X-ray image, with a maximum concentration Qmax of equivalent thickness image sets respectively, of the workpiece W thickness The conversion process of the equivalent thickness image corresponding to the length t to the density data Q (P) is executed by the above equation [1], and according to the X-ray irradiation output of the X-ray source 2 and the material of the workpiece W, the equation [ 1] Since the density data Q (P) of the equivalent thickness image is calculated while variably setting the correction index value γ, the density data Q (P) of the equivalent thickness image becomes the density of the foreground in the X-ray image. It will vary within the maximum density value Qmax of the equivalent thickness image in accordance with the ratio between the value P ₁ and the density value P of the X-ray image at each transmission region. Therefore, it is possible to suppress variations in measurement accuracy due to zero point drift of the X-ray detector. In addition, since the correction index value γ is corrected depending on the X-ray irradiation output of the X-ray source 2 and the material of the workpiece W, the straight line of the density data Q (P) of the equivalent thickness image with respect to the thickness of the workpiece W Therefore, coupled with the fact that the zero point correction is always performed, the influence of the temperature drift of the X-ray detector 4 and the like due to the ambient temperature change is eliminated without detecting the ambient temperature. Become. In the present embodiment, the conversion processing unit 62 performs correction for the density data Q (P) of the equivalent thickness image within a range where the correction index value is 1.3 ± 0.2. When the X-ray inspection is performed using a workpiece as a workpiece, it is possible to ensure good linearity of the equivalent thickness image density value Q (P).

In addition, the conversion processing unit 62 obtains the density value Q (Pa) of the equivalent thickness image based on the density value Pa of the X-ray image in the specific transmission region of the representative work serving as the standard of the work W, and this is expressed by the formula [ previously calculated values of the density values P ₂ in formula (2) is a representative density values of the foreground in Qa of the representative work as a value X-ray image 2], the foreground in the X-ray image representative density value P ₁ after having replaced the calculated density value P _2, so performs the conversion processing from the density data P of the X-ray image into density data Q of the equivalent thickness image (P), the foreground representative density set values in the X-ray image The preferable density according to the magnitude of the density value P corresponding to the detected transmission amount with respect to P ₁ depends on the variation of the transmission amount for each work W within the density range up to the maximum density setting value Qmax of the equivalent thickness image density. The correction index value γ Can exhibit an auto gain control function is not influenced by the variety of the work for the density data Q of the equivalent thickness image I linearity secured coupled with (P) by the adjustment.

  Further, in the X-ray inspection apparatus of the present embodiment, the zero point correction unit 61 includes a first area on the transport path 1 where the work W is placed and a second area where the work W is not placed. For a plurality of transmission regions separated from each other in the two regions, the transmission amount of X-rays transmitted through the conveyance path 1 is detected, and based on the X-ray transmission amounts of the plurality of transmission regions separated from each other in the second region, Since the zero point correction is performed, the zero point correction can be performed even during the volume measurement. In particular, a plurality of transmission regions that are separated from each other in the second region are located at both ends in the width direction of the conveyance path in the inspection space. Since the width direction ends 12a and 12b are separated from each other, the zero point correction can be executed in real time around an arbitrary area.

  Further, a predetermined placement width range of the work W on the conveyance path 1 based on the amount of X-rays transmitted through the conveyance path 1 in a plurality of transmission regions separated from the width direction both ends 12a and 12b of the conveyance path 1 Since the protrusion detection unit 69 for detecting the protrusion from the workpiece is provided, the transmission amount detection information for zero point correction can be used as information for detecting the protrusion from the predetermined placement width range of the workpiece. A simple protrusion detection means can be realized.

Further, the density values Pe ₁ of the X-ray images at both ends in the width direction of the conveyance path 1 corresponding to the transmission amounts of a plurality of transmission areas separated from the width direction both ends 12a and 12b of the conveyance path 1, for example, the monitoring points d1 and dn. Pe ₂ is determined, an offset density K that connects these density values Pe ₁ and Pe ₂ in a straight line is set, and inclination correction for transmission amount data of a plurality of transmission regions is executed together with zero point correction. Therefore, by subtracting the offset density from the density data P of the X-ray image, the zero point drift can be corrected simultaneously with the inclination correction for canceling the gradation of the background in the X-ray image.

  Moreover, in the present embodiment, the zero point correction unit 61 includes a conveyance interval detection unit 61a that specifies the conveyance interval of the workpiece W on the conveyance path 1, and corresponds to the conveyance interval based on the conveyance interval detection information. Since the second area (non-conveying section) is specified, the belt surface open area between the individual workpieces on the conveying path 1 is used regardless of the type of the workpiece W as long as the workpiece is not a continuous workpiece such as a loose article. Thus, it is possible to check the X-ray transmission amount of the belt surface in the entire width direction of the conveyance path and make a fine judgment on the effectiveness of zero point correction and inclination correction.

  [Second Embodiment]

  FIGS. 13 to 18 are views showing a second embodiment of the X-ray inspection apparatus according to the present invention, and show an example in which the present invention is applied to an X-ray foreign object detection apparatus having a mass measurement function. In this embodiment, the same or similar apparatus configuration as that of the above-described embodiment is added with means for foreign object detection, sensitivity correction, and taring, etc. The same reference numerals as those in FIG. 1 to FIG. 12 are used for simple explanation, and the differences from the above-described embodiment will be described in detail.

First, the configuration will be described.
As shown in FIG. 13, the X-ray inspection apparatus according to the present embodiment includes, as components similar to the X-ray inspection apparatus according to the above-described embodiment, a conveyance path 1 including a belt conveyor that conveys a workpiece W, An X-ray source 2 that irradiates the workpiece W with X-rays in a predetermined inspection space, an approach detection sensor 3 that includes, for example, a projector / receiver that detects the entry of the workpiece W into the inspection space, and a conveyance path in the inspection space An X-ray detector 4 capable of detecting X-rays transmitted through the workpiece W for each of a plurality of transmission regions adjacent in the width direction, and an X-ray transmitted through the workpiece W based on detection information of the X-ray detector 4 An image input unit 5 that generates density data corresponding to the accumulated transmission amount per predetermined time in each transmission area as density data P of the X-ray image, and X every predetermined time of each transmission area from the image input unit 5 The density data P of the line image Includes a processing unit 6 to generate a digital X-ray image, a by executing the image processing associated with the cell data.

  The processing unit 6 of the present embodiment exhibits the functions of, for example, a microcomputer having a CPU, a ROM, a RAM, and an I / O interface (not shown) and a plurality of processing function units, which will be described later, in substantially the same manner as the above-described embodiment. The auxiliary storage device that stores the control program for read-out in cooperation with the ROM includes a zero point correction unit 61, a conversion processing unit 62, a volume, In addition to including the measurement unit 63 and the mass conversion unit 66, the recording / reference unit 64, the sensitivity correction unit 65, and the foreign matter mixing determination unit 67 are further included. In addition to the mass conversion function described in the description of the first embodiment, the mass conversion unit 66 in the present embodiment has a function of taring.

The recording / reference unit 64 defines a standard workpiece made of a uniform and stable homogeneous resin or the like (for example, Delrin (registered trademark)), and the tube voltage E, tube current I, ambient temperature T and elapsed time of the X-ray source 2 The initial (T = T ₀ , H = H ₀ ) volume measurement value V ₀ (E, I, T ₀ , H ₀ ) of the reference workpiece, which changes according to H, can be read in advance as a reference table. Recorded and stored in memory form. The recording / reference unit 64 uses a predetermined volume measurement value V ₀ (E, I, T ₀ , H ₀ ) for a standard workpiece for setting the measurement sensitivity as a predetermined detection parameter (E, This is a sensitivity information storage unit that stores a volume measurement value table (not shown) associated with I) and a sensitivity correction coefficient β (T−T ₀ , H−H ₀ ) for correcting the sensitivity of volume measurement.

In addition, the sensitivity correction unit 65 can correct the correction coefficient β (T−T ₀ , H−) that can be updated at any time when a new volume measurement value V ₁ (E, I, T, H) of the reference workpiece is obtained. H ₀ ) = V ₀ (E, I, T ₀ , H ₀ ) / V ₁ (E, I, T, H) is calculated, and this correction coefficient β (T−T ₀ , H− H ₀ ) can be used to automatically calibrate the temperature drift of the detection sensitivity accompanying the ambient temperature and aging. The sensitivity correction unit 65, together with the recording / reference unit 64, specifies a predetermined detection parameter (E, I) related to the latest measurement value for each volume measurement of the standard workpiece and stores it in the recording / reference unit 64. Based on the reference volume measurement value table V ₀ (E, I, T ₀ , H ₀ ) and the latest volume measurement value V (E, I, T, H) of the reference workpiece, the sensitivity correction coefficient β ( (T−T ₀ , H−H ₀ ) is updated to constitute a sensitivity correction means for maintaining the sensitivity of volume measurement within a certain range.

When measuring the volume of the reference workpiece, the tube voltage E and the tube current I are set as a pair, so I is omitted and the ambient temperature and secular change, which are implicit variables, are omitted, and V ₀ (E) and It is only necessary to have a reference table β (E), and the explicit parameter E can be a predetermined parameter.

Here, by multiplying the calibrated volume measurement value V _proof of a certain work W by the mass conversion factor λ _W depending on the type of the work W, the volume measurement value V _proof of the work W can be converted into mass. Therefore, the sensitivity configuration in terms of mass can be indirectly performed by measuring the volume of the reference workpiece.
The volume measurement value V _proof calibrated by the sensitivity correction unit 65 is expressed by V _proof = β · V.

If the value converted into the mass unit is G, this converted value G can be expressed as G = λ _W · V _proof = λ _W · β · V.

When the work W includes a tare, the material of the tare is different from the contents of the work W. Therefore, when the tare is defined as another independent work C, the mass conversion coefficient is converted to λ _C for the tare. If the tare mass is G _C , the tare volume measurement value is V _C , and the calibrated volume measurement value is V _{C_proof} , it can be _expressed as G _C = λ _C · V _{C_proof} = λ _C · β · V _C .

Since the calibrated volume measurement value V _proof of the work W including the tare should include the calibrated volume measurement value V _{Cproof for} the tare, V _proof −V _Cproof as the net volume, It is necessary to perform conversion processing. Therefore, in this case, the mass converted value G ₀ from the net volume is G ₀ = λ _W · (V _proof −V _Cproof ) = λ _W · β · {V−G _C / (λ _C · β)} It becomes.

The mass conversion unit 66 is a first conversion for converting the volume measurement value V for each transmission region measured by the volume measuring means 63 into a conversion value G in mass units at a preset conversion ratio (conversion rate). A processing program, a second conversion processing program for converting the volume measurement value V _proof for each transmission region measured by the volume measuring means 63 into a conversion value G ₀ in mass units at a preset conversion ratio, and a workpiece It has a coefficient holding memory area for storing the mass conversion coefficients λ _W and λ _{C for} each type of _W , and a work memory area for conversion processing.

The mass conversion unit 66 is connected to the display unit 7a, and the mass converted value of the workpiece W converted into a mass unit by the mass conversion unit 66 (the entire workpiece W or a part of the workpiece W specified in advance). The value of G _{0 for} the corresponding area) or the volume measurement result of the workpiece W before conversion (the value of V _{0 for} the area corresponding to the entire workpiece W or a part of the components of the workpiece W specified in advance) Are output to the display unit 7a.

  On the other hand, the foreign matter mixing determination unit 67, for example, the density data Q (P) of the equivalent thickness image for each slice data converted by the conversion processing unit 62, or the density of the equivalent thickness image of the entire transmission region of the workpiece W, for example. Of the data Q (P), a differential process is performed to find a sharp change in the density data Q (P) between a plurality of adjacent transmission areas, and the transmission of the foreign object candidate points in the entire transmission area of the workpiece W A region is specified, and the presence or absence of foreign matter is determined by determining whether or not the X-ray absorption amount exceeds a predetermined threshold for the candidate point.

  Further, as described above, the position on the equivalent thickness image of the transmission area determined to have foreign matter is displayed and output on the foreign matter display portion 7b.

  In the volume measuring unit 63, when it is determined that foreign matter is mixed according to the foreign matter mixing determination result in the foreign matter mixing determining unit 67, the density data Q (P) of the equivalent thickness image of the corresponding transmission region is temporarily stored. In order to reduce the influence of foreign matter on the volume and mass measurement by performing interpolation of the data on the removed equivalent area using density data Q (P) of the equivalent thickness image of the transmissive area around it. It has become.

  Note that the X-ray inspection apparatus of the present embodiment uses any mode selection means (not shown) to select any one of a weighing mode for mass measurement only, a foreign object detection mode for only foreign object detection, and a combined mode for simultaneously performing mass measurement and foreign object detection. The operation mode can be selected.

  Next, the operation will be described.

As in the first embodiment described above, for the types whose setting parameters are unknown, first, the tube voltage E and the tube current I for specifying the irradiation intensity of the X-ray source 2 are appropriately set according to the type of the workpiece W. After setting the level, the detection sensitivity of the X-ray detector 4 is adjusted so that the X-ray transmission amount of each transmission region on the belt surface alone is the same value in the entire width direction on the non-transport conveyance path 1, Next, the belt surface of the conveyance path 1 at the time of non-conveyance is set as a zero point reference surface for volume measurement, a representative density P ₀ of the belt surface that is the background of the X-ray transmission image is set, and a foreground of the work W representative density P ₁ equivalent thickness image of the maximum density Qmax and the set, respectively. Then, if necessary, set a noise cut threshold value, etc., measure the volume of the master work (reference work) with known mass, and calculate from the set master work mass and the measured volume measurement value to set the mass conversion factor λ _W of place. As described above, these initial setting data are stored in the memory of the transport and X-ray irradiation control unit or the memory in the processing unit 6 and are referred to as appropriate.

  Further, these initial measurement data are written in the product type parameter file and read when an input for designating the product type is made.

  A series of measurement control programs similar to the measurement control programs of FIGS. 7 to 9 described above are executed for the types for which such settings have been made, and when an input for specifying the type of workpiece W to be measured is made, After a necessary selection operation input, an X-ray inspection is performed. However, in this embodiment, in order to perform foreign object detection, automatic calibration of sensitivity drift using a reference workpiece, and tare processing at the time of mass conversion, an expansion process as described below is executed.

  That is, following the above-described density conversion processing step (step S11 in FIG. 7), an expanded volume measurement process as shown in FIG. 14 is executed.

  In the figure, first, it is determined whether or not the operation mode is a mode with foreign object detection (step S51), and in the case of the operation mode with foreign object detection, the density data Q (P (P) converted in the density conversion processing step). ) Is also used for foreign object detection (in the case of YES in step S51).

  In this case, the conversion processing unit 62 specifies the foreign substance candidate point by the above-described differentiation process and the like, and determines whether or not the X-ray absorption amount for the candidate point exceeds a predetermined threshold value. The presence / absence of foreign matter is determined, and the determination result is displayed and output on the foreign matter display portion 7b (step S52). If it is determined that foreign matter is mixed, processing for reducing the influence of the mixed foreign matter is executed (step S53). Although this processing is not shown in detail in FIG. 14, it is not a foreign matter but also a desiccant or an accessory (a partition or a container corresponding to it) incorporated in the workpiece W. It is applicable to the process for excluding from the mass.

  In the case of foreign matter, a specific example is illustrated. For example, as shown in FIG. 17, the foreign matter (or attached product, etc.) F (refer to FIG. Although the part F of equal F becomes the high level which protruded (refer the figure (b)), as a mass distribution of the content, the display as shown in the figure (c) is made. In order to perform this display, in the present embodiment, as described above, the equivalent thickness image data of the transmission region of the foreign matter F is temporarily removed, and the removed transmission region is removed using, for example, the average value of the adjacent transmission regions. A process of interpolating the partial density data Q (P) is performed.

  Next, the volume calculation process of the workpiece W is performed in the same manner as the volume calculation process step S12 of the above-described embodiment.

In the present embodiment, the volume of the reference workpiece for sensitivity calibration is measured using the reference workpiece that serves as a reference for setting the detection sensitivity for collecting equivalent thickness data, and the measured value is used for the measurement. The table is recorded in the recording / reference unit 64 in association with the setting parameter (E, I) to be affected (step S54). In addition, the sensitivity correction unit 65 sets the correction coefficient β to β (T−T ₀ , H−H ₀ ) at each time point when a new volume measurement value V ₁ (E, I, T, H) of the reference workpiece is obtained. ) = V ₀ (E, I, T ₀ , H ₀ ) / V ₁ (E, I, T, H). By changing the parameters (E, I), recording / The reference unit 64 also stores the correction coefficient β as a table.

Accordingly, when a new volume measurement value V ₁ (E, I, T, H) of the reference workpiece is obtained (step S56), the newly calculated correction coefficient β (T−T ₀ , H−H ₀ ) is used. Thus, the calibrated volume measurement value V _proof = β · V with respect to the subsequent volume measurement value V is calculated, and the temperature drift of the detection sensitivity accompanying the ambient temperature and the secular change can be automatically calibrated (step S57). At this time, the sensitivity correction coefficient β = V ₀ / V ₁ , V ₀ is the volume measurement value of the reference workpiece at the reference temperature on the reference day, and V ₁ is the reference workpiece in the latest sensitivity correction performed using the reference workpiece. It is a volume measurement value.

Next, a mass conversion process is performed in which the converted value G converted to the mass unit is G = λ _W · V _proof = λ _W · β · V. In this embodiment, the mass conversion of the above-described embodiment is performed. On the other hand, an extended mass calculation process is performed as shown in FIG.

In the figure, first, the presence / absence of tare subtraction conversion is checked (step S61). That is, it is checked whether or not the workpiece W includes a tare C that is to be excluded from the mass measurement value of the contents. The designation is made in advance together with a setting input of a parameter (for example, a mass conversion coefficient λ _C ) necessary when setting a parameter before starting operation.

If tare there, its tare, mass conversion factor, respectively lambda _C, tare weight G _C in _terms, the volumetric value V _C of the tare _min, the calibrated volume measurements using a V _{C_proof,} G C ₌ λ can be expressed as _{C · V C_proof = λ C ·} β · V C, in the present embodiment, if the weight conversion factor lambda _C is set in advance, only specifies the tare mass G _C, taring Since it becomes possible, the mass value of the tare C is input and stored in the setting information memory as a setting parameter (step S62).

At this time, the mass conversion unit 66 reads the mass conversion coefficients λ _W and λ _C of the contents of the workpiece and the tare from the coefficient holding memory area, and calibrated volume measurement values V _proof measured by the volume measuring means 63. a preset conversion ratio i.e. mass conversion factor lambda _W, performs the second conversion processing program for converting the converted value G ₀ of the mass units lambda _C, first, the workpiece weight measurement of the tare mass G _C When subtraction from is specified (YES in step S61), the volume conversion process (V _C = G _C / (λ _C · β)) is performed based on the mass conversion coefficient λ _C which is a product type parameter. Te, subtraction of tare is made at the volume level, then the mass is converted from the volume _{V-V C} of the net (step S62~64). That is, a process of calculating the mass converted value G ₀ from the net volume V−V _C as G ₀ = λ _W · β · {V−G _C / (λ _C · β)} is executed (step S64). ). Here, the process of obtaining the partial volume using the density data Q (P) of the effective equivalent thickness in each transmission region and finally obtaining the sum is the same as in the above-described embodiment.

  When such a tare weight measurement is completed, the process after the pass / fail determination process (step S14 in FIG. 7) in the first embodiment described above is executed, and the determination result is a display unit together with other measurement information. It is displayed on the display part 7a and the foreign substance display part 7b.

  In this embodiment, the display is performed in a display mode as shown in FIG. 16, for example, by integrating the mass display portion 7a and the foreign matter display portion 7b in a single screen.

  An image display area 71 for displaying an X-ray image or equivalent thickness image of the workpiece W is arranged on the left side of the screen in the figure, and a mass distribution or equivalent thickness distribution of a specific X-ray section is displayed on the upper right side of the screen, or A distribution image display unit 72 showing the distribution of the mass for the entire width at each position in the length direction of the workpiece W (left and right direction in the figure) is below the mass display unit 73 and a mass pass / fail judgment result display unit 74. , A foreign matter determination result display unit 76, a foreign matter NG number display unit 77 for displaying the number of foreign matter NG generated, a mass NG number display unit 78 for displaying the number of generated mass NG, and a mass indicator unit 80 are provided. ing. In the distribution image display unit 72, when the work W includes foreign matter or an accessory having a high X-ray absorption coefficient (indicated by F in FIG. 16), the equivalent thickness concentration (X-ray absorption concentration) corresponding to the accessory is indicated. A high peak is displayed, but the influence is removed in mass measurement.

  Further, as shown in FIG. 18, the mass indicator unit 80 has a plurality of, for example, three or more light emitting portions that emit light sequentially from the left end in the drawing according to the mass measurement value of the workpiece W. Therefore, the display range (cross-hatched portion in the figure) is changed according to the mass measurement value of the workpiece W. Further, the light emitting portions having the same shape are arranged in a line so that the scales are arranged at equal intervals. Further, the mass indicator section 80 is provided below the indicator portion 81 with a first pointer 82 indicating the lower limit value of the allowable mass range by indicating the specific position of the indicator portion 81, and the upper limit value of the allowable mass range. A second pointer 83 indicated by indicating a specific position of the indicator portion 81 is provided. When a lower limit value and an upper limit value of the mass allowable range are input, the pointers 82 and 83 are displayed on the indicator portion 81. It moves in the left-right direction in the figure to indicate the corresponding mass position. Further, the indicator portion 81 has a most preferred mass value within the allowable range, for example, a thick scale line 84 located just in the center of the allowable range, and this scale line defaults to an intermediate value. It is also possible to specify the position to be deviated from the position.

  In this mass indicator portion 80, from the display range of the mass indicator portion 81, how much excess or deficiency or deviation of the measured mass with respect to the allowable range indicated by the interval between the first and second pointers 82 and 83 is detected. You can easily and intuitively know if you have it. In addition, since the result of setting the lower limit value and the upper limit value of the mass allowable range can be visually grasped as the positions of the first and second pointers 82 and 83 with respect to the mass indicator portion 81, operability is good.

As described above, in the present embodiment, the same effect as in the first embodiment can be obtained by performing real-time zero point correction in the same manner as in the first embodiment described above. Moreover, in the present embodiment, a predetermined detection parameter is specified for each volume measurement of the standard workpiece, and the volume measurement value table V ₀ (E, I, T) stored in the recording / reference unit 64 (sensitivity information storage unit). ₀ , H ₀ ) and the latest volume measurement value V ₁ (E, I, T, H) of the reference workpiece, the sensitivity correction coefficient β is updated to maintain the sensitivity of volume measurement within a certain range. Therefore, it is possible to accurately calibrate the detection sensitivity drift due to ambient temperature and aging.

When the volume V _{1 of the} standard workpiece is newly measured, the sensitivity correction unit 65 measures the latest measured volume value V ₁ (E, I) and the volume measurement stored in the recording / reference unit 64. Since the sensitivity correction coefficient β is updated based on the ratio with the reference volume measurement value V ₀ (E, I) in the value table, the tube voltage E of the X-ray source, the tube current I, the ambient temperature T, and the progress When the volume measurement value V ₀ (E, I, T ₀ , H ₀ ) of the reference workpiece that changes according to the period H is made into a reference table, each time the volume measurement value V ₁ of the reference workpiece is obtained, Thus, the temperature drift of the detection sensitivity can be calibrated accurately and easily.

In the present embodiment, when the workpiece W includes the tare C, the volume measuring unit 63 calculates the volume measurement value V of the entire workpiece calculated based on the density data Q (P) of the equivalent thickness image of the workpiece W. since tare process of subtracting the volume value V _C tare content, even when the workpiece W includes a tare, it is possible to output the volume and mass of the tare was contents directly. Furthermore, the volume measuring unit 63 stores the tare mass and volume conversion ratio in advance, and when the tare mass is set, converts the mass to the tare volume and executes the tare processing. The taring process can be executed only by inputting the tare mass value.

  In the present embodiment, since the foreign matter presence / absence judgment unit 67 that judges the presence / absence of a foreign matter in the workpiece W based on the detection information of the X-ray detector 4 and detects the foreign matter is provided, not only the volume or mass measurement is performed. Foreign matter detection can be performed, and variation factors such as temperature drift of the X-ray detector 4 are eliminated by zero point correction, thereby suppressing variation in mass measurement accuracy and variation in foreign matter detection accuracy due to temperature drift and aging. be able to.

  Further, the processing unit 6 removes the data transmitted through the foreign matter from the data corresponding to the X-ray transmission amount when the foreign matter is detected according to the detection result of the foreign matter presence / absence determination unit 67 and Since the process of interpolating the removed data is executed based on the transmission amount data in the surrounding area, the apparatus can always obtain the mass measurement result independently from the foreign object detection.

  Moreover, since the display parts 7a and 7b have the mass indicator part 80 which changes a display range according to the mass measurement value of the workpiece | work W, measured mass is immediately from the display range of the mass indicator part 80. Visible.

  As described above, the present invention enables zero point correction in real time while inspecting a workpiece by executing zero point correction at an appropriate cycle according to the volume measurement cycle of the workpiece. It is possible to provide an X-ray inspection apparatus capable of providing a X-ray inspection apparatus capable of removing variation factors such as drift by zero point correction and preventing variation in measurement accuracy due to temperature drift, It is especially useful for all X-ray inspection devices that irradiate the workpiece being transported with X-rays and perform volume measurement or mass measurement with the X-ray transmission amount, or even detect foreign matter. is there.

It is the block diagram which shows schematic structure of 1st Embodiment of the X-ray inspection apparatus which concerns on this invention. It is the perspective view which shows the arrangement | positioning of the fan beam optical system and the range of a workpiece | work mounting area | region in 1st Embodiment of the X-ray inspection apparatus which concerns on this invention. It is explanatory drawing of the zero point correction | amendment in 1st Embodiment of the X-ray inspection apparatus which concerns on this invention. It is explanatory drawing of inclination correction | amendment in 1st Embodiment of the X-ray inspection apparatus which concerns on this invention. It is explanatory drawing of the effective range setting of the volume calculation process using the noise cut threshold value in 1st Embodiment of the X-ray inspection apparatus which concerns on this invention. It is explanatory drawing of the protrusion detection system in 1st Embodiment of the X-ray inspection apparatus which concerns on this invention. It is a flowchart which shows the general | schematic flow of the measurement control program in the 1st Embodiment of this invention. It is a flowchart which shows the general | schematic flow of the zero point correction | amendment processing program in the 1st Embodiment of this invention. It is a flowchart which shows the general | schematic flow of the density | concentration conversion processing program in the 1st Embodiment of this invention. It is a flowchart which shows the general | schematic flow of the volume measurement processing program in the 1st Embodiment of this invention. It is explanatory drawing which shows the calculation method of an example which calculates | requires the sum total of a partial volume with the volume measurement processing program in the 1st Embodiment of this invention by comparing with a representative workpiece | work and a test | inspection workpiece | work with an equivalent thickness image. It is a screen block diagram which shows an example of the display mode of the display means in 1st Embodiment of the X-ray inspection apparatus which concerns on this invention. It is the block diagram which shows schematic structure of 2nd Embodiment of the X-ray inspection apparatus which concerns on this invention. It is a flowchart which shows the general | schematic flow of the extended volume measurement processing program in the 2nd Embodiment of this invention. It is a flowchart which shows the general | schematic flow of the extended mass calculation processing program in the 2nd Embodiment of this invention. It is a screen block diagram which shows an example of the display mode of the display means in 2nd Embodiment of the X-ray inspection apparatus which concerns on this invention. It is explanatory drawing explaining the process which removes the influence on the mass measurement of the mixed foreign material at the time of the mass measurement in the 2nd Embodiment of this invention. It is an enlarged front view of the mass indicator part of the display means in 2nd Embodiment of the X-ray inspection apparatus which concerns on this invention.

Explanation of symbols

1 Conveyance path 2 X-ray source 3 Ingress detection sensor (conveyance interval detection unit)
4 X-ray detector 5 Image input unit (image input means)
6 Processing unit 11 Central part of conveyance path width direction (first area)
12a One end of conveyance path width direction (second region)
12b Transport path width direction other end (second region)
61 Zero point correction unit 62 Conversion processing unit (data conversion processing means)
62a Linearity correction unit 63 Volume measuring unit (volume measuring means)
64 Recording / reference unit (sensitivity information storage unit)
65 Sensitivity correction unit (sensitivity correction means)
66 Mass conversion part (conversion means)
66a Mass acceptance / rejection determination unit (mass acceptance / rejection determination means)
67 Foreign matter mixing judgment part (foreign matter detection means)
69 Projection detection unit (Projection detection means)
80 Mass indicator part K Offset density Pe ₁ , Pe ₂ X-ray image density values at both ends in the width direction

Claims (18)

A transport path (1) for transporting the workpiece;
An X-ray source (2) for irradiating the workpiece being conveyed with X-rays in a predetermined inspection space;
An X-ray detector (4) capable of detecting X-rays transmitted through the workpiece for each of a plurality of transmission regions adjacent in a direction orthogonal to the transport direction in the inspection space;
A processing unit (6) for processing data corresponding to the transmission amount of the X-rays transmitted through the workpiece for each transmission region based on the detection information of the X-ray detector to generate a digital X-ray image. , An X-ray inspection apparatus for measuring the volume of the workpiece based on the X-ray image,
The processing unit (6)
A background density value (P0) in the X-ray image, a foreground representative density (P1) in the X-ray image, a maximum density (Qmax) of the equivalent thickness image, and a correction index value (γ) are set. Then, according to the following equation [1]
By calculating the density data (Q (P)) of the equivalent thickness image, the equivalent thickness corresponding to the thickness of the workpiece in each of the transmission areas from the density data (P) of the X-ray image in each transmission area. Data conversion processing means (62) for performing conversion processing to density data (Q (P)) of the image;
Volume measuring means (63) for measuring the volume of the workpiece in the plurality of transmission regions based on density data of the equivalent thickness image corresponding to each of the plurality of transmission regions;
A zero point correction unit that processes the data corresponding to the X-ray transmission amount and corrects the density data of the X-ray image to zero so that the equivalent thickness of the background when the X-ray is irradiated to the workpiece is zero. (61) and
The data conversion processing means calculates the linearity of the density data of the equivalent thickness image corresponding to the thickness of the workpiece within the predetermined range set according to the workpiece, the X-ray irradiation output of the X-ray source, and the In order to obtain the linearity of the density data (Q (P)) of the equivalent thickness image with respect to the thickness of the workpiece in each transmission region of the non-defective workpiece among the workpieces to be inspected according to the workpiece material. A linearity correction unit (62a) for correcting by adjusting the correction index value of [1] .
The zero point correction unit (61) executes the zero point correction based on density data whose linearity is corrected by the linearity correction unit according to a cycle of measuring the volume of the workpiece. X-ray inspection equipment.   The apparatus further comprises conversion means (66) for converting the volume measurement value of each transmission region measured by the volume measurement means into a conversion value in mass unit at a preset conversion ratio (λW). Item 2. The X-ray inspection apparatus according to Item 1. 2. The X-ray according to claim 1 , wherein the data conversion processing unit corrects the density data of the equivalent thickness image within a range where the correction index value is 1.3 ± 0.2. Inspection device. The data conversion processing means includes
The density value Q (Pa) of the equivalent thickness image calculated by the above equation [1] based on the density value Pa of the X-ray image in a specific transmission region of the representative workpiece serving as the standard of the workpiece is expressed by the following equation [2]. The foreground in the X-ray image of the representative workpiece is calculated using the calculated Qa value of the equivalent thickness image and the density value Pa of the X-ray image in the specific transmission region of the representative workpiece. The value of the density value P2 in the formula [2] that is the representative density value of
The representative density value (P1) of the foreground in the X-ray image is replaced with the calculated density value (P2), and the X-ray image density data (P) in each of the transmission regions corresponds to the thickness of the workpiece. The X-ray inspection apparatus according to claim 1 , wherein a conversion process for converting an equivalent thickness image having a density to density data (Q (P)) is executed.   The zero point correction unit is spaced apart from each other in the second region among the first region (11) where the workpiece is placed on the conveyance path and the second region (12a, 12b) where the workpiece is not placed. Detecting a transmission amount of X-rays transmitted through the conveyance path for a plurality of transmission regions, and performing the zero point correction based on the X-ray transmission amounts of the transmission regions separated from each other in the second region The X-ray inspection apparatus according to claim 1, wherein: 6. The X-ray inspection according to claim 5 , wherein a plurality of transmission regions separated from each other in the second region are separated from each other in the width direction end portions (12 a, 12 b) of the transport path in the inspection space. apparatus. Based on a transmission amount of X-rays transmitted through the transport path in the plurality of transmission regions spaced from both ends in the width direction of the transport path, from a predetermined placement width range (11) of the workpiece on the transport path The X-ray inspection apparatus according to claim 6 , further comprising a protrusion detection unit that detects a protrusion. The density of the X-ray image at both ends in the width direction of the transport path corresponding to both transmission amount values based on the amount of X-rays transmitted through the plurality of transmission regions spaced at both ends in the width direction of the transport path By determining the values (Pe1, Pe2) and setting the offset density (K) that linearly connects the density values of the X-ray images at both ends, the inclination correction for the transmission amount data of the plurality of transmission regions is performed. The X-ray inspection apparatus according to claim 6 , wherein the X-ray inspection apparatus is executed together with the zero point correction. The zero point correction unit includes a conveyance interval detection unit (3) that specifies the conveyance interval of the workpiece on the conveyance path, and based on detection information of the conveyance interval detection unit, as a range corresponding to the conveyance interval The X-ray inspection apparatus according to claim 5 , wherein the second region is specified.   Sensitivity information for storing a volume measurement value table that associates a reference volume measurement value for a reference workpiece for setting measurement sensitivity with a predetermined detection parameter that affects the measurement sensitivity, and a sensitivity correction coefficient that corrects the sensitivity of the volume measurement. A storage unit (64) for specifying the predetermined detection parameter for each volume measurement of the reference workpiece, and a volume measurement value table stored in the sensitivity information storage unit and the latest volume measurement value of the reference workpiece; And a sensitivity correction means (65) for updating the sensitivity correction coefficient based on the predetermined detection parameter at the time of measurement and maintaining the sensitivity of the volume measurement within a certain range. The X-ray inspection apparatus according to claim 1. When the predetermined detection parameter includes at least a value of a voltage for driving the X-ray source, and the volume of the reference workpiece is measured, the sensitivity correction unit includes the measured latest volume measurement value, The X-ray inspection apparatus according to claim 10 , wherein the sensitivity correction coefficient is updated based on a ratio with the volume measurement value in the volume measurement value table stored in a sensitivity information storage unit.   2. The X measurement according to claim 1, wherein the volume measuring unit executes a volume measurement process using density data exceeding a predetermined noise cut threshold among density data of an X-ray image in each transmission region. Line inspection device.   Mass that determines pass / fail of the mass measurement result based on whether or not the converted value of the volume measurement value for each transmission region converted into the mass unit value by the conversion means is within a predetermined mass tolerance range corresponding to the workpiece. The X-ray inspection apparatus according to claim 2, further comprising pass / fail judgment means (66a).   When the workpiece includes a tare (C), the volume measuring means calculates the volume value (VC) of the tare from the volume measurement value (V) of the entire workpiece calculated based on the density data of the equivalent thickness image of the workpiece. The X-ray inspection apparatus according to claim 1, wherein a tare subtraction process for subtracting () is executed.   When the workpiece includes a tare (C), the volume measuring means stores the tare mass and volume conversion ratio (λC) in advance, and when the tare mass (GC) is set, the mass Is converted into the tare volume, and the tare processing is performed by subtracting the volume value (VC) of the tare from the volume measurement value (V) of the entire workpiece calculated based on the density data of the equivalent thickness image of the workpiece. The X-ray inspection apparatus according to claim 2, wherein:   The foreign object detection means (67) which determines the presence or absence of the foreign material in the said workpiece | work based on the detection information of the said X-ray detector, and detects this foreign material is further provided. X-ray inspection equipment. The processing unit removes the data transmitted through the foreign matter from the data corresponding to the X-ray transmission amount when the foreign matter is detected according to the detection result of the foreign matter detection means, and The X-ray inspection apparatus according to claim 16 , wherein a process of interpolating the removed data is executed based on density data of an X-ray image in the surrounding transmission region.   The X-ray inspection apparatus according to claim 2, further comprising display means having a mass indicator unit (80) that changes a display range according to a mass measurement value of the workpiece.