JP2009250635A - X-ray inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an X-ray inspection device capable of properly dealing with the lowering problem of a detection capacity caused by polarization without stopping the operation of a production line on the assumption that a direct conversion type X-ray sensor is used. <P>SOLUTION: The X-ray inspection device 1 includes an X-ray irradiation part 7, an X-ray detection part 8 having the X-ray sensor of a type which directly converts X rays to an electric signal, a belt conveyor 6 for feeding an article 12 so that the article 12 passes through the X-ray irradiation region 100 between the X-ray irradiation part 7 and the X-ray detection part 8 and a control part 60 for controlling the bias voltage applied to the X-ray sensor. The X-ray detection part 8 has the X-ray line sensor 8A arranged on the feed route of the article 12 and the X-ray line sensor 8B arranged in parallel to the X-ray line sensor 8A on the downstream side of the X-ray line sensor 8A. The control part 60 can independently apply bias voltage to the X-ray line sensors 8A and 8B. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an X-ray inspection apparatus.

  Conventionally, in the food industry, indirect conversion type X-ray sensors have been widely used as X-ray sensors used in X-ray inspection apparatuses for inspecting the presence or absence of foreign matters in food. In an indirect conversion type X-ray sensor, X-rays that have passed through an inspection object are converted into visible light by a scintillator, and visible light emitted from the scintillator is converted into an electrical signal by a photodiode.

  However, the indirect conversion type X-ray sensor has a drawback in that the foreign matter detection performance is low because the spatial resolution is reduced due to scattering of light inside the scintillator. On the other hand, due to consumer demands for food safety, high detection performance has been required even for food X-ray inspection apparatuses. Even in an indirect conversion type X-ray sensor, it is possible to increase detection performance by increasing the X-ray dose. However, when the irradiation X-ray dose is increased, the X-ray dose that passes through the scintillator and is applied to the photodiode also increases. As a result, the durability of the photodiode is lowered and the frequency of parts replacement is increased, which increases the user's economic burden.

  Under such circumstances, the food industry is expected to put the X-ray sensor of the direct conversion method into practical use instead of the indirect conversion method. The direct conversion type X-ray sensor is currently used mainly for CT apparatus in the medical field, and a semiconductor sensor (CdTe sensor) using cadmium telluride (CdTe) is known. For example, Patent Document 1 below discloses an example of a CT apparatus using a CdTe sensor. The direct conversion type X-ray sensor does not include a scintillator, and the X-ray transmitted through the inspection object is directly converted into an electric signal. The direct conversion type X-ray sensor has a high spatial resolution because it is not affected by light scattering by the scintillator, and also has a high X-ray conversion efficiency. Therefore, compared with the indirect conversion type X-ray sensor, the irradiation X-ray dose is small. High-definition images can be obtained. Therefore, since the irradiation X-ray dose can be suppressed, it is possible to suppress a decrease in durability of the semiconductor sensor due to the X-ray irradiation.

JP 2003-294844 A

  As described above, the direct conversion type X-ray sensor is expected to be put into practical use also in the food industry, but there is a particular problem when the direct conversion type X-ray sensor is used in the food industry. In other words, in the food industry, unlike CT apparatuses in the medical field, there is a situation in which X-ray inspection apparatuses are used continuously for a long time. Some food factories have a production line that operates all day, and an X-ray inspection apparatus incorporated in such a production line inevitably operates all day.

  When the direct conversion type X-ray sensor is continuously used for a long time, the influence of polarization (polarization) becomes large. When polarization occurs, the sensitivity of the X-ray sensor decreases, and as a result, the detection performance of the X-ray inspection apparatus also decreases. Therefore, when a direct conversion type X-ray sensor is used in the food industry, it is necessary to appropriately cope with the problem of deterioration in detection performance due to polarization while maintaining continuous operation of the production line.

  The present invention has been made in view of such circumstances, and is suitable for the problem of deterioration in detection performance due to polarization without stopping the operation of the production line on the premise of using a direct conversion type X-ray sensor. An object is to obtain an X-ray inspection apparatus capable of coping with the above.

  An X-ray inspection apparatus according to a first aspect of the present invention is an X-ray inspection apparatus that inspects an article by irradiating the article to be inspected with X-rays and detecting the X-ray transmitted through the article. An X-ray irradiation unit, an X-ray detection unit having an X-ray sensor of a type that directly converts X-rays into an electrical signal, and the article between the X-ray irradiation unit and the X-ray detection unit A transport unit that transports the article so as to pass through the X-ray irradiation region, and a control unit that controls a bias voltage applied to the X-ray sensor, wherein the X-ray detection unit includes a transport path of the article A first X-ray sensor disposed above, and a second X-ray sensor disposed adjacent to the first X-ray sensor on the downstream side of the first X-ray sensor. And the control unit biases the first X-ray sensor and the second X-ray sensor. Characterized in that it is capable of applying pressure independently.

  The X-ray inspection apparatus according to a second aspect of the invention is the X-ray inspection apparatus according to the first aspect of the invention, and in particular, the control unit alternates with respect to the first X-ray sensor and the second X-ray sensor. A bias voltage is applied to the capacitor.

  The X-ray inspection apparatus according to a third aspect of the invention is the X-ray inspection apparatus according to the second aspect of the invention. In particular, the control unit applies a bias voltage application destination from the second X-ray sensor to the first X-ray. When switching to the sensor, the bias voltage is continuously applied to the second X-ray sensor until a predetermined time elapses after the application of the bias voltage to the first X-ray sensor is started. It is characterized by.

  The X-ray inspection apparatus according to the fourth invention is the X-ray inspection apparatus according to the second or third invention, in particular, the data output from the first X-ray sensor and the second X-ray sensor, respectively. It further comprises a storage unit for storing.

  The X-ray inspection apparatus according to a fifth aspect of the invention is the X-ray inspection apparatus according to the first aspect of the invention, in particular, the X-ray detector is the second X-ray on the downstream side of the second X-ray sensor. And a third X-ray sensor disposed adjacent to the sensor, wherein the control unit includes the first X-ray sensor, the second X-ray sensor, and the third X-ray sensor. On the other hand, the bias voltage can be applied independently.

  The X-ray inspection apparatus according to a sixth aspect of the invention is the X-ray inspection apparatus according to the fifth aspect of the invention, in particular, the control unit alternately with respect to the first X-ray sensor and the second X-ray sensor. A bias voltage is applied to the third X-ray sensor, and a bias voltage is applied to the third X-ray sensor in common with the first X-ray sensor.

  The X-ray inspection apparatus according to a seventh aspect of the invention is the X-ray inspection apparatus according to the fifth aspect of the invention, in particular, the control unit alternately with respect to the first X-ray sensor and the second X-ray sensor. When a bias voltage is applied to the first X-ray sensor, the bias voltage is applied to at least the first X-ray sensor when the application destination of the bias voltage is switched from the second X-ray sensor to the first X-ray sensor. Then, a bias voltage is applied to the third X-ray sensor until a predetermined time elapses.

  An X-ray inspection apparatus according to an eighth invention is the X-ray inspection apparatus according to any one of the fifth to seventh inventions, in particular, the first X-ray sensor, the second X-ray sensor, and the A storage unit is further provided for storing data respectively output from the third X-ray sensor.

  According to the X-ray inspection apparatus according to the first to eighth inventions, even if polarization has occurred in the X-ray sensor by continuous use until then, by stopping the application of the bias voltage to the X-ray sensor, The characteristics of the X-ray sensor can be restored to the initial characteristics. In addition, since a bias voltage can be independently applied to each of a plurality of X-ray sensors, the bias application stop operation is performed by controlling the timing so that the bias application stop period does not overlap. It can be executed without stopping. Therefore, it is possible to avoid the occurrence of a situation where the operation of the entire production line is stopped due to the X-ray inspection apparatus becoming a bottleneck.

  In particular, according to the X-ray inspection apparatus according to the second invention, it is possible to avoid overlapping bias application stop periods by alternately applying a bias voltage to the first and second X-ray sensors.

  In particular, according to the X-ray inspection apparatus according to the third aspect of the invention, when the bias voltage application destination is switched from the downstream second X-ray sensor to the upstream first X-ray sensor, the first X-ray sensor is used. The bias voltage is continuously applied to the second X-ray sensor until a predetermined time elapses after the application of the bias voltage is started. Thereby, it is possible to avoid the occurrence of an uninspected area in the article.

  In particular, according to the X-ray inspection apparatus according to the fourth invention, by temporarily storing each output data of the first and second X-ray sensors in the storage unit, at the time of data output from the storage unit, It becomes possible to synchronize the output data of the first X-ray sensor and the output data of the second X-ray sensor, and it becomes easy to create an image based on these output data.

  In particular, according to the X-ray inspection apparatus according to the fifth aspect of the invention, by providing three (or three sets) of X-ray sensors, the bias application stop period can be reduced compared to the case of two (or two sets). Variations in timing control that do not overlap can be expanded.

  In particular, according to the X-ray inspection apparatus of the sixth invention, a bias voltage is alternately applied to the most upstream first X-ray sensor and the central second X-ray sensor, and the most downstream third X-ray sensor is applied. A bias voltage is applied to the X-ray sensor in common with the first X-ray sensor. Thereby, it is possible to avoid the occurrence of an uninspected area in the article.

  In particular, according to the X-ray inspection apparatus according to the seventh aspect of the invention, the bias voltage is alternately applied to the uppermost first X-ray sensor and the center second X-ray sensor. Further, when switching the application destination of the bias voltage from the second X-ray sensor to the first X-ray sensor, at least a predetermined time elapses after the application of the bias voltage to the first X-ray sensor is started. Until the most downstream third X-ray sensor is applied. Thereby, it is possible to avoid the occurrence of an uninspected area in the article.

  In particular, according to the X-ray inspection apparatus according to the eighth invention, by temporarily storing each output data of the first to third X-ray sensors in the storage unit, at the time of data output from the storage unit, It is possible to synchronize the output data of the first to third X-ray sensors, and it becomes easy to create an image based on these output data.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the element which attached | subjected the same code | symbol in different drawing shall show the same or corresponding element.

  FIG. 1 is a front view schematically showing the overall configuration of an X-ray inspection apparatus 1 according to the present invention. As shown in FIG. 1, the X-ray inspection apparatus 1 includes an upper housing 2, a shield box 3, and a lower housing 4. The upper housing 2 is provided with a monitor with a touch panel function, that is, a display / input unit 5.

  The shield box 3 has a function of preventing X-rays from leaking to the outside. An X-ray irradiation unit 7 and an X-ray detection unit 8 are disposed in the shield box 3. The X-ray irradiation unit 7 irradiates the article 12 such as food that is the inspection target with X-rays. The X-ray detection unit 8 detects X-rays that have been irradiated from the X-ray irradiation unit 7 and transmitted through the article 12. If foreign matter is mixed in the article 12, the intensity of X-rays detected by the X-ray detection unit 8 is extremely reduced at the portion where the foreign matter is mixed. Thereby, the magnitude | size and mixing location of a foreign material can be specified.

  A belt conveyor 6 is disposed in the shield box 3. The belt conveyor 6 conveys the article 12 in the conveyance direction indicated by the arrow H so that the article 12 passes through the X-ray irradiation region 100 (see FIG. 2) between the X-ray irradiation unit 7 and the X-ray detection unit 8. To do. It is detected that the article 12 is supplied to the X-ray inspection apparatus 1 from the processing apparatus upstream of the X-ray inspection apparatus 1 at the upstream end of the belt conveyor 6 (that is, outside the shield box 3 near the article carry-in entrance 17). A photo sensor 15 is provided. That is, the photo sensor 15 can detect that the article 12 has reached the upstream end of the belt conveyor 6. The shield box 3 is provided with an article carry-in port 17 near the upstream end of the belt conveyor 6 and an article carry-out port 18 near the downstream end.

  A computer 9 for performing operation control and data processing of the X-ray inspection apparatus 1 is disposed in the lower housing 4.

  On the upstream side of the belt conveyor 6, a belt conveyor 10 for carrying the article 12 from the upstream processing apparatus to the X-ray inspection apparatus 1 is provided. A belt conveyor 11 for carrying out the inspected article 12 from the X-ray inspection apparatus 1 is provided on the downstream side of the belt conveyor 6. The belt conveyor 11 is provided with an arbitrary sorting mechanism 20 for sorting non-defective products and defective products based on the result of inspection by the X-ray inspection apparatus 1.

  FIG. 2 is a perspective view showing an internal configuration of the shield box 3 shown in FIG. An X-ray irradiator (hereinafter also referred to as “X-ray irradiator 7”) as an X-ray irradiator 7 is disposed above the belt conveyor 6. Below the belt conveyor 6, an X-ray detector 8 is disposed. As shown as an X-ray irradiation region 100 in FIG. 2, the X-ray irradiator 7 emits X-rays in a fan shape toward the X-ray detector 8.

Embodiment 1 FIG.
FIG. 3 is a perspective view showing a first example of the configuration of the X-ray detection unit 8 shown in FIG. 2, and FIG. 4 shows a second example of the configuration of the X-ray detection unit 8 shown in FIG. It is a perspective view shown. In the first embodiment, an example in which the X-ray detection unit 8 is configured to include two X-ray line sensors 8A and 8B will be described.

  Referring to FIGS. 3 and 4, an X-ray line sensor 8A is disposed on the article conveyance path indicated by arrow H (strictly below the conveyance path), and downstream of X-ray line sensor 8A. An X-ray line sensor 8B is disposed adjacent to the X-ray line sensor 8A on the side. Specifically, the X-ray line sensor 8B is disposed in parallel to the X-ray line sensor 8A. In the example shown in FIG. 3, the X-ray line sensors 8A and 8B are provided with separate X-ray conversion films 41A and 41B, respectively. In the example shown in FIG. 4, the X-ray line sensors 8A and 8B are integrated. An X-ray conversion film 41 is provided in common.

  3 and 4, X-ray line sensors 8A and 8B each include a plurality of X-ray detection elements arranged in a straight line. In each X-ray line sensor 8 </ b> A, 8 </ b> B, the plurality of X-ray detection elements are the radial direction (Z-axis direction) of the article placement surface of the belt conveyor 6 and the conveyance direction (Y-axis direction) of the article 12 by the belt conveyor 6. Are arranged side by side along a direction (X-axis direction) orthogonal to.

  The X-ray line sensor 8A includes a bias electrode 40A common to a plurality of X-ray detection elements and a pixel electrode 42A provided for each X-ray detection element. Similarly, the X-ray line sensor 8B includes a bias electrode 40B common to a plurality of X-ray detection elements and a pixel electrode 42B provided for each X-ray detection element. In the example shown in FIG. 4, bias electrodes which are electrically and physically separated from each other by patterning a conductive film such as metal formed on the entire surface of the X-ray conversion film 41 using a photolithography technique or the like. 40A and 40B can be formed.

  The X-ray line sensors 8A and 8B are direct conversion type X-ray sensors, and the X-ray conversion films (41, 41A, 41B) are made of, for example, CdTe or CdZnTe. Each X-ray detection element directly converts X-rays that have passed through the bias electrode and applied to the X-ray conversion film into an electrical signal by the X-ray conversion film. In a direct conversion type X-ray sensor, when an X-ray conversion film to which a bias voltage is applied is irradiated with X-rays, charges (electron-hole pairs) are generated in the X-ray conversion film according to the irradiated X-ray dose. Is excited and a current flows. The current value is converted into a voltage value by a current / voltage conversion circuit and output as data.

  FIG. 5 is a circuit diagram showing a bias application circuit to the X-ray line sensors 8A and 8B. The power supply 30 supplies a bias voltage to be applied to the bias electrodes 40A and 40B of the X-ray line sensors 8A and 8B. A switch 31A composed of a transistor or a semiconductor relay is connected between the power supply 30 and the X-ray line sensor 8A. When the switch 31A is ON, a bias voltage is applied from the power source 30 to the X-ray line sensor 8A. On the other hand, when the switch 31A is OFF, the bias voltage is applied from the power source 30 to the X-ray line sensor 8A. Is not applied. Similarly, a switch 31B is connected between the power supply 30 and the X-ray line sensor 8B, and whether or not a bias voltage is applied from the power supply 30 to the X-ray line sensor 8B is controlled by turning on / off the switch 31B. it can.

  Current / voltage conversion circuits 8AA and 8BB are connected to the X-ray line sensors 8A and 8B, respectively. The current / voltage conversion circuits 8AA and 8BB change the current values flowing through the X-ray line sensors 8A and 8B to voltage values and output the data (voltage signals), respectively.

  Data output from the current / voltage conversion circuits 8AA and 8BB is input to memories 35A and 35B as storage units, respectively. The memories 35A and 35B are configured by, for example, a register or a RAM, and can temporarily hold data input from the current / voltage conversion circuits 8AA and 8BB, respectively. Data output from the memories 35A and 35B is input to the computer 9, and an image of the article 12 is created by the computer 9.

  FIG. 6 is a block diagram showing a functional configuration of the X-ray inspection apparatus 1 according to the first embodiment. The computer 9 includes a CPU 51 and a memory 52 such as a RAM or a ROM that can be referred to by the CPU 51. An X-ray irradiator 7, memories 35 </ b> A and 35 </ b> B, a display / input unit 5, a photo sensor 15, switches 31 </ b> A and 31 </ b> B, and a distribution mechanism 20 are connected to the computer 9. Current / voltage conversion circuits 8AA and 8BB are connected to the memories 35A and 35B, respectively.

  By the way, in the direct conversion type X-ray sensor, it is known that when a bias voltage is continuously applied, polarization occurs and the sensitivity of the X-ray sensor decreases. Hereinafter, a critical continuous application time in which the influence of polarization on sensitivity is significant is referred to as a limit time Tmax. That is, by continuously applying the bias voltage to the X-ray line sensors 8A and 8B for a time equal to or longer than the limit time Tmax, the influence of polarization increases and the sensitivity of the X-ray sensor decreases. However, in reality, there is no clear critical value as the limit time Tmax, and the sensitivity of the X-ray sensor has started to decrease due to experiments or simulations at the development stage of the X-ray inspection apparatus or X-ray sensor. The value of the continuous application time at the time point (or the time point immediately before starting to decrease) is set as the limit time Tmax.

  In operation of the production line, if there are frequent rest periods in which the article 12 is not supplied to the X-ray inspection apparatus 1, by stopping application of the bias voltage to the X-ray line sensors 8A and 8B within each rest period, The X-ray line sensors 8A and 8B can be recovered from the polarization state. However, some food factories have production lines that are continuously operated throughout the day, and the X-ray inspection apparatus 1 incorporated in such a production line does not have a rest period and therefore cannot perform a recovery operation from the polarization state. . Therefore, in the X-ray inspection apparatus 1 according to the first embodiment, a bias voltage can be independently applied to the X-ray line sensors 8A and 8B, and an X-ray detection operation is executed by one X-ray line sensor. Meanwhile, the recovery operation from the polarization state is executed for the other X-ray line sensor. This will be specifically described below.

  FIG. 7 is a block diagram showing a configuration related to the recovery operation from the polarization state. The control unit 60 is realized as a function of the computer 9 shown in FIGS. The controller 60 can control ON / OFF of the switch 31A by the signal S1A. Similarly, the control unit 60 can control ON / OFF of the switch 31B by the signal S1B.

  FIG. 8 is a timing chart showing the operation of the X-ray inspection apparatus 1 according to the first embodiment. FIG. 8A shows the ON / OFF state of the switch 31A, and shows the ON state when the waveform is at a high level and the OFF state when the waveform is at a low level. FIG. 8B shows the ON / OFF state of the switch 31B, showing the ON state when the waveform is at a high level and the OFF state when the waveform is at a low level.

  FIG. 8C shows a state in which a bias voltage is applied to the bias electrode 40A. A predetermined bias voltage is applied when the waveform is at a high level, and an applied voltage is zero when the waveform is at a low level. Each state is shown. FIG. 8D shows a state in which a bias voltage is applied to the bias electrode 40B. When the waveform is at a high level, a predetermined bias voltage is applied, and when the waveform is at a low level, the applied voltage is zero. Each state is shown. In (C) and (D) of FIG. 8, the transition between the high level and the low level is inclined in consideration of the stabilization time of the bias voltage.

  FIG. 8E shows the data output state from the X-ray line sensor 8A (strictly, the current / voltage conversion circuit 8AA). When the waveform is at high level, the data output state is At the level, it shows the state where no data is output. FIG. 8F shows the data output state from the X-ray line sensor 8B (strictly, the current / voltage conversion circuit 8BB). When the waveform is at a high level, the data output state is At the level, it shows the state where no data is output.

  FIG. 8G shows a data output state from the memory 35A, which shows a state in which data is output when the waveform is at a high level and a state in which no data is output when the waveform is at a low level. ing. FIG. 8H shows a data output state from the memory 35B, and shows a state where data is output when the waveform is at a high level, and a state where data is not output when the waveform is at a low level. ing.

  As shown in FIGS. 8A and 8B, when the switches 31A and 31B are alternately turned ON / OFF, the bias electrodes 40A and 40B are turned on as shown in FIGS. A bias voltage is alternately applied to.

  Further, when the application destination of the bias voltage is switched from the downstream X-ray line sensor 8B to the upstream X-ray line sensor 8A, the switch 31B is not turned OFF at the same time as the switch 31A is turned ON. The switch 31B remains on until a predetermined time elapses after the switch 31A is turned on. For example, even if the switch 31A is turned on at time T3, the switch 31B is turned on until time T5. Thereby, for example, after data output from the X-ray line sensor 8A is started at time T4, data output from the X-ray line sensor 8B is stopped at time T5. This predetermined time is set based on the stabilization time of the bias voltage and the conveyance speed of the belt conveyor 6. At least the stabilization time of the bias voltage and the time required for the same location in the article 12 to travel from above the X-ray line sensor 8A to above the X-ray line sensor 8B (referred to as “required time required”). A time longer than the total is set as the predetermined time. When the bias voltage application timing is used as a reference instead of the switch switching timing, the bias voltage is applied to the bias electrode 40B from the start of application of the bias voltage to the bias electrode 40A until a predetermined time longer than the required time has elapsed. This means that the application of the bias voltage is continued.

  Further, as shown in FIGS. 8E and 8F, the start point and end point of the data output period related to the X-ray line sensor 8A do not match the end point and start point of the data output period related to the X-ray line sensor 8B, respectively. However, as shown in FIGS. 8G and 8H, the start and end points of the data output period related to the memory 35A coincide with the end point and start point of the data output period related to the memory 35B, respectively. That is, the data output period (that is, the data input period to the computer 9) is synchronized with respect to the X-ray line sensors 8A and 8B through the memories 35A and 35B. More specific description will be given with reference to FIG.

  FIG. 9 is a diagram for explaining data output synchronization by the memories 35A and 35B. FIG. 9A shows the relative positional relationship between the X-ray line sensors 8A and 8B and the article 12. For convenience, the article 12 is divided into a front end portion L, a central portion M, and a rear end portion N in order from the head in the traveling direction. At time T01, the tip portion L is located above the X-ray line sensor 8A, and at time T02, the center portion M and the tip portion L are located above the X-ray line sensors 8A and 8B, respectively. At time T03, the rear end portion N and the central portion M are located above the X-ray line sensors 8A and 8B, respectively, and at time T04, the rear end portion N is located above the X-ray line sensor 8B. Yes.

  FIG. 9B shows data input to the memories 35A and 35B in correspondence with FIG. 9A. Data relating to the front end portion L at time T01, data relating to the central portion M at time T02, and data relating to the rear end portion N at time T03 are input to the memory 35A. In addition, the memory 35B receives data related to the front end portion L at time T02, data related to the central portion M at time T03, and data related to the rear end portion N at time T04. That is, the data is not synchronized at the time of data input to the memories 35A and 35B.

  FIG. 9C shows data output from the memories 35A and 35B. From the memories 35A and 35B, data related to the leading end portion L is output at time T03, data related to the central portion M is output at time T04, and data related to the trailing end portion N is output at time T05. That is, the data is synchronized at the time of data output from the memories 35A and 35B. The memory 35B corresponding to the downstream X-ray line sensor 8B can be omitted. In this case, the data output from the memory 35A and the data output from the X-ray line sensor 8B are synchronized. Is taken. For example, at time T02, data related to the tip portion L is output from the memory 35A, and data related to the tip portion L is output from the X-ray line sensor 8B, and both data are input to the computer 9 in synchronization. .

  As described above, according to the X-ray inspection apparatus 1 according to the first embodiment, by stopping the application of the bias voltage to the X-ray line sensors 8A and 8B, the X-ray line sensors 8A and 8A, Even if polarization occurs in 8B, the characteristics of the X-ray line sensors 8A and 8B can be restored to the initial characteristics. In addition, since the bias voltage can be independently applied to each of the two X-ray line sensors 8A and 8B, the bias application stop operation is performed by controlling the timing so that the bias application stop periods do not overlap. Can be executed without stopping the production line. Therefore, it is possible to avoid a situation in which the operation of the entire production line is stopped due to the X-ray inspection apparatus 1 becoming a bottleneck.

  In addition, according to the X-ray inspection apparatus 1 according to the first embodiment, it is possible to avoid overlapping bias application stop periods by alternately applying a bias voltage to the X-ray line sensors 8A and 8B. .

  Further, according to the X-ray inspection apparatus 1 according to the first embodiment, when the application destination of the bias voltage is switched from the downstream X-ray line sensor 8B to the upstream X-ray line sensor 8A, the X-ray line sensor 8A. The bias voltage is continuously applied to the X-ray line sensor 8B until a predetermined time elapses after the application of the bias voltage is started. Thereby, it can avoid that the area | region which is not test | inspected generate | occur | produces in the articles | goods 12. FIG.

  In addition, according to the X-ray inspection apparatus 1 according to the first embodiment, the output data of the X-ray line sensors 8A and 8B are temporarily stored in the memories 35A and 35B, whereby the data from the memories 35A and 35B is stored. When outputting, the output data of the X-ray line sensor 8A and the output data of the X-ray line sensor 8B can be synchronized. As a result, the computer 9 can easily create an image based on these output data.

Embodiment 2. FIG.
FIG. 10 is a perspective view illustrating a third example of the configuration of the X-ray detection unit 8 illustrated in FIG. 2, and FIG. 11 illustrates a fourth example of the configuration of the X-ray detection unit 8 illustrated in FIG. It is a perspective view shown. In the second embodiment, an example in which the X-ray detection unit 8 is configured to include three X-ray line sensors 8A to 8C will be described.

  Referring to FIGS. 10 and 11, an X-ray line sensor 8A is disposed on the article conveyance path indicated by arrow H (strictly below the conveyance path), and downstream of X-ray line sensor 8A. An X-ray line sensor 8B is disposed adjacent to (for example, parallel to) the X-ray line sensor 8A on the side, and further adjacent to the X-ray line sensor 8B on the downstream side of the X-ray line sensor 8B. An X-ray line sensor 8C is disposed (for example, in parallel). In the example shown in FIG. 10, the X-ray line sensors 8A, 8B, and 8C are provided with separate X-ray conversion films 41A, 41B, and 41C, respectively. In the example shown in FIG. 8C includes an integral X-ray conversion film 41 in common.

  Referring to FIGS. 10 and 11, X-ray line sensors 8 </ b> A to 8 </ b> C are each provided with a plurality of X-ray detection elements arranged in a straight line. In each of the X-ray line sensors 8A to 8C, a plurality of X-ray detection elements are arranged in parallel along the X-axis direction shown in the drawing.

  The structures of the X-ray line sensors 8A and 8B are the same as those shown in FIGS. The X-ray line sensor 8C is a direct conversion type X-ray sensor, and includes a bias electrode 40C common to a plurality of X-ray detection elements and a pixel electrode 42C provided for each X-ray detection element. In the example shown in FIG. 11, bias electrodes electrically and physically separated from each other by patterning a conductive film made of metal or the like formed entirely on the X-ray conversion film 41 using a photolithography technique or the like. 40A-40C can be formed.

  FIG. 12 is a circuit diagram showing a bias application circuit to the X-ray line sensors 8A to 8C. The power supply 30 supplies a bias voltage to be applied to the bias electrodes 40A, 40B, and 40C of the X-ray line sensors 8A, 8B, and 8C. Switches 31A, 31B, and 31C are connected between the power supply 30 and the X-ray line sensors 8A, 8B, and 8C, respectively, and the X-ray line sensor 8A from the power supply 30 is turned on / off by the switches 31A, 31B, and 31C. , 8B, 8C can be controlled respectively.

  Current / voltage conversion circuits 8AA, 8BB, and 8CC are connected to the X-ray line sensors 8A, 8B, and 8C, respectively. The current / voltage conversion circuits 8AA, 8BB, and 8CC change the current values flowing through the X-ray line sensors 8A, 8B, and 8C to voltage values, and output the data (voltage signals), respectively.

  Data output from the current / voltage conversion circuits 8AA, 8BB, and 8CC are input to memories 35A, 35B, and 35C as storage units, respectively. The memories 35A, 35B, and 35C are configured by, for example, a register or a RAM, and can temporarily hold data input from the current / voltage conversion circuits 8AA, 8BB, and 8CC, respectively. Data output from the memories 35 </ b> A to 35 </ b> C is input to the computer 9, and an image of the article 12 is created by the computer 9.

  FIG. 13 is a block diagram showing a functional configuration of the X-ray inspection apparatus 1 according to the second embodiment. A memory 35C, a current / voltage conversion circuit 8CC, and a switch 31C are added to the configuration shown in FIG.

  FIG. 14 is a block diagram showing a configuration related to the recovery operation from the polarization state. A switch 31C is added to the configuration shown in FIG. The controller 60 can control ON / OFF of the switch 31C by the signal S1C.

  FIG. 15 is a timing chart showing a first operation example of the X-ray inspection apparatus 1 according to the second embodiment. 15A shows the ON / OFF state of the switch 31A, FIG. 15B shows the ON / OFF state of the switch 31B, and FIG. 15C shows the ON / OFF state of the switch 31C. , Respectively. When the waveform is at the high level, the ON state is shown, and when the waveform is at the low level, the OFF state is shown.

  15D shows the bias voltage application state to the bias electrode 40A, FIG. 15E shows the bias voltage application state to the bias electrode 40B, and FIG. 15F shows the bias voltage application state to the bias electrode 40C. The application state of the bias voltage is shown respectively. When the waveform is at a high level, a state where a predetermined bias voltage is applied is shown, and when the waveform is at a low level, a state where the applied voltage is zero is shown.

  15G shows the data output state from the X-ray line sensor 8A (strictly, the current / voltage conversion circuit 8AA), and FIG. 15H shows the X-ray line sensor 8B (strictly, the current / voltage conversion). The data output state from the circuit 8BB) and FIG. 15I show the data output state from the X-ray line sensor 8C (strictly, the current / voltage conversion circuit 8CC). When the waveform is at a high level, the data is being output, and when the waveform is at a low level, the data is not being output.

  (J) in FIG. 15 shows a data output state from the memory 35A, (K) in FIG. 15 shows a data output state from the memory 35B, and (L) in FIG. 15 shows a data output state from the memory 35C. ing. When the waveform is at a high level, the data is being output, and when the waveform is at a low level, the data is not being output.

  As shown in FIGS. 15A to 15C, when the switches 31A and 31C and the switch 31B are alternately turned ON / OFF, as shown in FIGS. Bias voltages are alternately applied to the electrodes 40A and 40C and the bias electrode 40B.

  Further, as shown in FIGS. 15G to 15I, the end point of the data output period related to the X-ray line sensor 8A does not coincide with the start point of the data output period related to the X-ray line sensor 8B. The end point of the data output period related to the line line sensor 8B does not coincide with the start point of the data output period related to the X-ray line sensor 8C. On the other hand, as shown in FIGS. 15J to 15L, the end point of the data output period related to the memory 35A coincides with the start point of the data output period related to the memory 35B, and the data output period related to the memory 35B. And the start point of the data output period related to the memory 35C coincide with each other. That is, the data output period (that is, the data input period to the computer 9) is synchronized with respect to the X-ray line sensors 8A to 8C by passing through the memories 35A to 35C. A more specific description will be given with reference to FIG.

  FIG. 16 is a diagram for explaining synchronization of data output by the memories 35A to 35C. FIG. 16A shows the relative positional relationship between the X-ray line sensors 8A to 8C and the article 12. At time T01, the tip portion L is located above the X-ray line sensor 8A, and at time T02, the center portion M and the tip portion L are located above the X-ray line sensors 8A and 8B, respectively. At time T03, the rear end portion N, the central portion M, and the front end portion L are located above the X-ray line sensors 8A, 8B, and 8C, respectively. At time T04, the X-ray line sensors 8B, 8C The rear end portion N and the central portion M are located above, respectively, and at the time T05, the rear end portion N is located above the X-ray line sensor 8C.

  FIG. 16B shows data input to the memories 35A to 35C in correspondence with FIG. Data relating to the front end portion L at time T01, data relating to the central portion M at time T02, and data relating to the rear end portion N at time T03 are input to the memory 35A. In addition, the memory 35B receives data related to the front end portion L at time T02, data related to the central portion M at time T03, and data related to the rear end portion N at time T04. In addition, data relating to the leading end portion L at time T03, data relating to the central portion M at time T04, and data relating to the trailing end portion N at time T05 are input to the memory 35C. That is, the data is not synchronized at the time of data input to the memories 35A to 35C.

  FIG. 16C shows data output from the memories 35A to 35C. From the memories 35A to 35C, data related to the leading end portion L is output at time T04, data related to the central portion M is output at time T05, and data related to the trailing end portion N is output at time T06. That is, the data is synchronized at the time of data output from the memories 35A to 35C. Note that the memory 35C corresponding to the most downstream X-ray line sensor 8C can be omitted, and in this case, between the data output from the memories 35A and 35B and the data output from the X-ray line sensor 8C. Is synchronized. For example, at time T03, data related to the tip portion L is output from the memories 35A and 35B, data related to the tip portion L is output from the X-ray line sensor 8C, and all data is input to the computer 9 in synchronization. It becomes.

  FIG. 17 is a timing chart showing a second operation example of the X-ray inspection apparatus 1 according to the second embodiment. As in FIG. 15, (A), (B), and (C) in FIG. 17 show the ON / OFF states of the switches 31A, 31B, and 31C, and (D), (E), and (F) in FIG. The bias voltage application state to the bias electrodes 40A, 40B, and 40C is shown in FIGS. 17 (G), (H), and (I), and the data output states from the X-ray line sensors 8A, 8B, and 8C are shown in FIG. (J), (K), and (L) indicate the data output states from the memories 35A, 35B, and 35C, respectively.

  As shown in FIGS. 17A and 17B, when the switches 31A and 31B are alternately turned ON / OFF, the bias electrodes 40A and 40B are turned on as shown in FIGS. A bias voltage is alternately applied to.

  Further, when the application destination of the bias voltage is switched from the downstream X-ray line sensor 8B to the upstream X-ray line sensor 8A, the switch 31A is turned ON and a predetermined time elapses after the switch 31B is turned OFF. During this period, the switch 31C is ON. For example, when the switch 31A is turned on and the switch 31B is turned off at time T7, the switch 31C is turned on until a predetermined time elapses from time T7. However, the timing at which the switch 31C is turned on may be before the timing at which the switch 31B is turned off. This predetermined time is set based on the stabilization time of the bias voltage and the conveyance speed of the belt conveyor 6. At least a time longer than the sum of the stabilization time of the bias voltage and the time required for the same location in the article 12 to travel from above the X-ray line sensor 8B to above the X-ray line sensor 8C (required time required). Is set as the predetermined time. If the bias voltage application timing is used as a reference instead of the switch switching timing, the bias voltage 40C is applied to the bias electrode 40C until a predetermined time longer than the required arrival time elapses after the application of the bias voltage to the bias electrode 40A is started. This means that the application of the bias voltage is continued.

  As shown in FIGS. 17G to 17I, the end point of the data output period for the X-ray line sensor 8A does not coincide with the start point of the data output period for the X-ray line sensor 8B. The end point of the data output period related to the line line sensor 8B does not coincide with the start point of the data output period related to the X-ray line sensor 8C. On the other hand, as shown in FIGS. 17J to 17L, the end point of the data output period related to the memory 35A coincides with the start point of the data output period related to the memory 35B, and the data output period related to the memory 35B. And the start point of the data output period related to the memory 35C are coincident with the end point of the data output period related to the memory 35C and the start point of the data output period related to the memory 35A. That is, the data output period (that is, the data input period to the computer 9) is synchronized with respect to the X-ray line sensors 8A to 8C by passing through the memories 35A to 35C.

  As described above, according to the X-ray inspection apparatus 1 according to the second embodiment, by stopping the application of the bias voltage to the X-ray line sensors 8A to 8C, the X-ray line sensors 8A to 8C are continuously used until then. Even if polarization occurs in 8C, the characteristics of the X-ray line sensors 8A to 8C can be restored to the initial characteristics. Also, since a bias voltage can be independently applied to each of the three X-ray line sensors 8A to 8C, the bias application stop operation is performed by controlling the timing so that the bias application stop periods do not overlap. Can be executed without stopping the production line. Therefore, it is possible to avoid a situation in which the operation of the entire production line is stopped due to the X-ray inspection apparatus 1 becoming a bottleneck.

  Further, according to the X-ray inspection apparatus 1 according to the second embodiment, by providing three X-ray line sensors, a variation in timing control that does not overlap the bias application stop period compared to the case of two X-ray line sensors. Can be spread.

  Further, according to the first operation example (FIG. 15) of the X-ray inspection apparatus 1 according to the second embodiment, the most upstream X-ray line sensor 8A and the central X-ray line sensor 8B are alternately arranged. A bias voltage is applied, and a bias voltage is applied to the most downstream X-ray line sensor 8C in common with the X-ray line sensor 8A. Thereby, it can avoid that the area | region which is not test | inspected generate | occur | produces in the articles | goods 12. FIG.

  Further, according to the second operation example (FIG. 17) of the X-ray inspection apparatus 1 according to the second embodiment, the most upstream X-ray line sensor 8A and the central X-ray line sensor 8B are alternately arranged. A bias voltage is applied to. Further, when switching the application destination of the bias voltage from the X-ray line sensor 8B to the X-ray line sensor 8A, at least until a predetermined time elapses after the application of the bias voltage to the X-ray line sensor 8A is started. A bias voltage is applied to the most downstream X-ray line sensor 8C. Thereby, it can avoid that the area | region which is not inspected in the articles | goods 12 generate | occur | produces.

  Further, according to the X-ray inspection apparatus 1 according to the second embodiment, the output data of the X-ray line sensors 8A to 8C is temporarily stored in the memories 35A to 35C, whereby the data from the memories 35A to 35C is stored. When outputting, it is possible to synchronize the output data of the X-ray line sensors 8A to 8C. As a result, the computer 9 can easily create an image based on these output data.

Modified example.
Hereinafter, modifications of the first and second embodiments will be described.

  The number of X-ray line sensors is not limited to the above two or three, but may be four or more.

  Each of the plurality of X-ray sensors arranged in parallel along the article conveyance path is not limited to a line sensor (an X-ray sensor in which a plurality of X-ray detection elements are arranged in a line), but is an area sensor (a plurality of X-ray sensors). An X-ray sensor in which line detection elements are arranged in a matrix may be used. Theoretically, a first X-ray sensor including at least one X-ray detection element and a second X-ray sensor including at least one X-ray detection element are arranged in parallel along the conveyance path of the article. If provided, the effects of the present invention can be exhibited.

  The recovery operation from the polarization state may be executed within a period in which the article 12 is not present on the belt conveyor 6. Whether or not the article 12 is present on the belt conveyor 6 can be detected by the photosensor 15.

  FIG. 18 is a diagram for specifically explaining the operation of stopping the application of bias to the X-ray line sensor 8. In FIG. 18, the X-ray line sensor 8 corresponds to the X-ray line sensors 8A to 8C of the first and second embodiments, and the switch 31 corresponds to the switches 31A to 31C of the first and second embodiments. The switch 31 has terminals 71A to 71C. When the switch 31 is turned on, the terminals 71A and 71B are connected, and when the switch 31 is turned off, the terminals 71A and 71C are connected. Stopping the application of the bias voltage to the X-ray line sensor 8 means that the switch 31 is switched to the OFF state in (A) to (D) of FIG.

  In FIG. 18A, the power source 70A supplies a minute voltage (for example, 0.1 V) having the same polarity as that of the power source 30, and even if the terminal 71A and the terminal 71C are connected to the X-ray line sensor 8. Since a sufficient bias voltage is not supplied, the X-ray line sensor 8 does not operate. In FIG. 18B, the terminal 71C is in an electrically floating state, and even if the terminal 71A and the terminal 71C are connected, a sufficient bias voltage is not supplied to the X-ray line sensor 8. The line sensor 8 does not operate. In FIG. 18C, the GND potential is supplied to the terminal 71C, and even if the terminal 71A and the terminal 71C are connected, a sufficient bias voltage is not supplied to the X-ray line sensor 8. The line sensor 8 does not operate. In FIG. 18D, the power source 70C supplies a minute voltage (for example, −0.1 V) having a polarity opposite to that of the power source 30. Even if the terminal 71A and the terminal 71C are connected, the X-ray line sensor is supplied. Since a sufficient bias voltage is not supplied to 8, the X-ray line sensor 8 does not operate.

It is a front view which shows typically the whole structure of the X-ray inspection apparatus which concerns on this invention. It is a perspective view which shows the internal structure of the shield box shown in FIG. It is a perspective view which shows the 1st example of a structure of the X-ray detection part shown in FIG. It is a perspective view which shows the 2nd example of a structure of the X-ray detection part shown in FIG. It is a circuit diagram which shows the bias application circuit to an X-ray line sensor. It is a block diagram which shows the function structure of the X-ray inspection apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure relevant to the recovery operation from a polarization state. It is a timing chart which shows operation | movement of the X-ray inspection apparatus which concerns on Embodiment 1 of this invention. It is a figure for demonstrating the synchronization of the data output by a memory. It is a perspective view which shows the 3rd example of a structure of the X-ray detection part shown in FIG. It is a perspective view which shows the 4th example of a structure of the X-ray detection part shown in FIG. It is a circuit diagram which shows the bias application circuit to an X-ray line sensor. It is a block diagram which shows the function structure of the X-ray inspection apparatus which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure relevant to the recovery operation from a polarization state. It is a timing chart which shows the 1st operation example of the X-ray inspection apparatus which concerns on Embodiment 2 of this invention. It is a figure for demonstrating the synchronization of the data output by a memory. It is a timing chart which shows the 2nd operation example of the X-ray inspection apparatus which concerns on Embodiment 2 of this invention. It is a figure for demonstrating concretely the stop operation | movement of the bias application to a X-ray line sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray inspection apparatus 6 Belt conveyor 7 X-ray irradiation part 8 X-ray detection part 8A-8C X-ray line sensor 9 Computer 12 Goods 35A-35C Memory 60 Control part 100 X-ray irradiation area | region

Claims (8)

An X-ray inspection apparatus that performs an inspection on the article by irradiating the article to be inspected with X-rays and detecting the X-ray transmitted through the article,
An X-ray irradiation unit;
An X-ray detector having an X-ray sensor of a type that directly converts X-rays into an electrical signal;
A transport unit that transports the product such that the product passes through an X-ray irradiation region between the X-ray irradiation unit and the X-ray detection unit;
A control unit for controlling a bias voltage applied to the X-ray sensor,
The X-ray detection unit
A first X-ray sensor disposed on the conveyance path of the article;
A second X-ray sensor disposed adjacent to the first X-ray sensor on the downstream side of the first X-ray sensor;
The control unit is an X-ray inspection apparatus capable of independently applying a bias voltage to the first X-ray sensor and the second X-ray sensor.   The X-ray inspection apparatus according to claim 1, wherein the control unit alternately applies a bias voltage to the first X-ray sensor and the second X-ray sensor.   The controller, when switching the application destination of the bias voltage from the second X-ray sensor to the first X-ray sensor, starts applying the bias voltage to the first X-ray sensor and then performs a predetermined operation. The X-ray inspection apparatus according to claim 2, wherein a bias voltage is continuously applied to the second X-ray sensor until time elapses.   The X-ray inspection apparatus according to claim 2, further comprising a storage unit that stores data respectively output from the first X-ray sensor and the second X-ray sensor. The X-ray detection unit further includes a third X-ray sensor disposed adjacent to the second X-ray sensor on the downstream side of the second X-ray sensor,
2. The X according to claim 1, wherein the controller can independently apply a bias voltage to the first X-ray sensor, the second X-ray sensor, and the third X-ray sensor. Line inspection device. The controller is
Alternately applying a bias voltage to the first X-ray sensor and the second X-ray sensor;
The X-ray inspection apparatus according to claim 5, wherein a bias voltage is applied to the third X-ray sensor in common with the first X-ray sensor. The controller is
Alternately applying a bias voltage to the first X-ray sensor and the second X-ray sensor;
When switching the application destination of the bias voltage from the second X-ray sensor to the first X-ray sensor, at least a predetermined time has elapsed since the application of the bias voltage to the first X-ray sensor was started. The X-ray inspection apparatus according to claim 5, wherein a bias voltage is applied to the third X-ray sensor until this is done.   8. The storage device according to claim 5, further comprising a storage unit that stores data output from each of the first X-ray sensor, the second X-ray sensor, and the third X-ray sensor. The X-ray inspection apparatus described.

Images