JP2011089964A - Article inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an article inspection device capable of using a common signal processing part, even if specifications, including the size and pitch of a pixel are different. <P>SOLUTION: A conversion part 20 includes an X-ray conversion film 30 and a plurality of pixel electrodes 32 contacting the X-ray conversion film 30. A signal processing part 21 includes a circuit board 33 on which a circuit for processing electric signals is formed, and a plurality of connection electrodes 34 formed on the circuit board 33 and connected to the pixel electrodes 32 via solder bumps 35. An electric charge 51, generated in the X-ray conversion film 30, is removed from the pixel electrodes 32 to the solder bumps 35. One pixel electrode 32 overlaps with two or more connection electrodes 34 as seen in planar view. The maximum distance K2 from an electric charge generation point 61 to an electric charge extracting point 62 in the pixel 60, in planar view, is set to be smaller than the maximum dimension K1 of the pixel 60 in planar view. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an article 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. Further, for example, Patent Document 2 below discloses an example of a radiation detection method 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. Direct conversion type X-ray sensors are not affected by light scattering by the scintillator, and therefore have high spatial resolution and high X-ray conversion efficiency. 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 Japanese Patent No. 3151487

FIG. 11 is a diagram schematically showing the structure of the direct conversion type X-ray sensor 101. As shown in FIG. 11, the X-ray sensor 101 includes a conversion unit 102 and a signal processing unit 103. In the conversion unit 102, a bias electrode 111 is formed on the upper surface of the X-ray conversion film 110. A pixel electrode 112 is formed on the bottom surface of the X-ray conversion film 110 so as to correspond to each pixel of the X-ray sensor 101. In the signal processing unit 103, a plurality of connection electrodes 114 are formed on the upper surface of the circuit board 113. The pixel electrodes 112 and the connection electrodes 114 have a one-to-one correspondence, and the pixel electrodes 112 and the connection electrodes 114 are physically and electrically connected to each other through solder bumps 115. The charges generated in the X-ray conversion film 110 by being irradiated with X-rays are taken out to the circuit board 113 as electric signals by passing through the pixel electrodes 112, the solder bumps 115, and the connection electrodes 114 in this order.

  By the way, in the article inspection apparatus, the specifications of the X-ray sensor 101 such as the pixel size and the pitch may differ depending on the type of article to be inspected and the required inspection accuracy. Here, in the X-ray sensor 101 shown in FIG. 11, the pixel electrodes 112 of the conversion unit 102 and the connection electrodes 114 of the signal processing unit 103 correspond one-to-one. Therefore, when the size and formation pitch of the pixel electrodes 112 differ depending on the specifications of the X-ray sensor 101, it is necessary to prepare the signal processing unit 103 having the connection electrodes 114 according to each specification. That is, since it is necessary to prepare a pair of the conversion unit 102 and the signal processing unit 103 for each different specification, the production efficiency is poor.

  The present invention has been made in view of such circumstances, and an object thereof is to obtain an article inspection apparatus that can use a common signal processing unit even if specifications such as pixel size and pitch are different. It is.

  An article inspection apparatus according to a first aspect of the present invention irradiates a conveyance unit that conveys an article to be inspected, and an electromagnetic wave or particle beam having a transmission effect on the article that is conveyed by the conveyance unit. An irradiating unit for detecting the electromagnetic wave or the particle beam transmitted through the article, the detecting unit converting the electromagnetic wave or the particle beam into an electric signal, and a signal processing unit for processing the electric signal The conversion unit receives the electromagnetic wave or particle beam that has passed through the article and generates an electric charge according to the electromagnetic wave or particle beam, thereby directly transmitting the electromagnetic wave or particle beam to the electric signal. The signal processing unit includes a circuit board on which a circuit for processing the electrical signal is formed, and a bump formed on the circuit board. Before A plurality of connection electrodes connected to the pixel electrode, the charge generated in the conversion film is taken out from the pixel electrode to the bump, and one pixel electrode is seen in plan view with respect to the plurality of connection electrodes The pixel is overlapped, and the maximum distance in plan view from the charge generation point to the charge extraction point in the pixel is set to be less than the maximum dimension in plan view of the pixel.

  According to the article inspection apparatus according to the first aspect, one pixel electrode overlaps the plurality of connection electrodes in plan view. Therefore, even if the area of the pixel electrode and the formation pitch are different due to different specifications of the conversion unit, it is possible to connect the pixel electrode by appropriately selecting the connection electrode on which the bump is to be formed. The electrodes can be connected to each other via bumps. As a result, a common signal processor can be used even if the specifications of the converters are different. Further, the maximum distance in plan view from the charge generation point to the charge extraction point in the pixel is set to be less than the maximum dimension in plan view of the pixel. Therefore, the charge generated in the conversion film can be taken out to the circuit board through the bumps quickly and without applying a high voltage.

  In the article inspection apparatus according to the second aspect of the present invention, in particular, in the article inspection apparatus according to the first aspect, one pixel electrode is connected to the plurality of connection electrodes via the plurality of bumps. It is characterized by this.

  According to the article inspection apparatus according to the second aspect, by connecting one pixel electrode to a plurality of connection electrodes via a plurality of bumps, a plan view from a charge generation point to a charge extraction point in the pixel is obtained. The maximum distance can be set to be less than the maximum dimension of the pixel in plan view. Therefore, the charge generated in the conversion film can be taken out to the circuit board through the bumps quickly and without applying a high voltage.

  The article inspection apparatus according to a third aspect of the present invention is the article inspection apparatus according to the first aspect, in particular, the pixel electrode is connected to the connection electrode via the bump at a substantially central portion in plan view. It is characterized by being connected.

  According to the article inspection apparatus according to the third aspect, the pixel electrode is connected to the connection electrode via the bump at a substantially central portion in a plan view, so that from the charge generation point to the charge extraction point in the pixel. The maximum distance in the plan view can be set to be less than the maximum dimension in the plan view of the pixel. Therefore, the charge generated in the conversion film can be taken out to the circuit board through the bumps quickly and without applying a high voltage. In addition, as compared with the case where one pixel electrode is connected to a plurality of connection electrodes via a plurality of bumps, the number of bumps can be reduced, so that loss of charge proportional to the number of bumps can be suppressed.

  According to the present invention, it is possible to use a common signal processing unit even if specifications such as pixel size and pitch are different.

It is a front view which shows typically the whole structure of the X-ray inspection apparatus which concerns on embodiment of this invention. It is a perspective view which shows the internal structure of the shield box shown in FIG. It is a top view which shows typically the structure of the X-ray detection part seen from the Y-axis direction. It is a top view which shows an example of the formation pattern of the connection electrode on a circuit board. FIG. 5 is a top view showing a pixel electrode formation pattern superimposed on the structure shown in FIG. 4. It is a figure which expands and shows a part of structure shown in FIG. It is a figure which expands and shows a part of structure shown in FIG. FIG. 5 is a top view showing another pixel electrode formation pattern superimposed on the structure shown in FIG. 4. It is a figure which expands and shows a part of structure shown in FIG. FIG. 5 is a top view showing another pixel electrode formation pattern superimposed on the structure shown in FIG. 4. It is a figure which shows typically the structure of the X-ray sensor of a direct conversion system.

  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 an overall configuration of an X-ray inspection apparatus 1 according to an embodiment of 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 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 has a predetermined conveyance direction (XYZ shown in the drawing) 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. The article 12 is conveyed along the Y-axis direction in the orthogonal coordinate axis. The shield box 3 is provided with an article carry-in port 13 near the upstream end of the belt conveyor 6 and an article carry-out port 14 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 15 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.

  FIG. 3 is a plan view schematically showing the structure of the X-ray detector 8 viewed from the Y-axis direction. As shown in FIG. 3, the X-ray detection unit 8 includes a conversion unit 20 that converts an X-ray into an electric signal, and a signal processing unit 21 that processes the electric signal generated by the conversion unit 20.

  The conversion unit 20 includes an X-ray conversion film 30, a bias electrode 31 formed on the entire top surface of the X-ray conversion film 30, and a plurality of pixel electrodes 32 formed on the bottom surface of the X-ray conversion film 30. is doing. The plurality of pixel electrodes 32 are arranged in parallel along the X-axis direction at a predetermined formation pitch P2 and orthogonal to the Y-axis direction (including the case of being substantially orthogonal). The pixel electrode 32 is provided corresponding to each pixel. The X-ray detection unit 8 is a direct conversion type X-ray sensor, and the X-ray conversion film 30 is made of, for example, CdTe or CdZnTe. The X-ray detection unit 8 may be a line sensor in which only one pixel column is provided, or a plurality of pixels are arranged in a matrix by providing a plurality of pixel columns along the Y-axis direction. It may be an area sensor (surface sensor).

  The signal processing unit 21 is configured as an ASIC or the like, and includes a circuit board 33 on which a semiconductor integrated circuit for performing signal processing is formed, and a plurality of connection electrodes 34 formed on the upper surface of the circuit board 33. Yes. The plurality of connection electrodes 34 are arranged in parallel along the X-axis direction at a predetermined formation pitch P1.

  The formation pitch P2 of the pixel electrodes 32 is set larger than the formation pitch P1 of the connection electrodes 34. In the example shown in FIG. 3, the formation pitch P2 is set to twice the formation pitch P1.

  FIG. 4 is a top view illustrating an example of a formation pattern of the connection electrode 34 on the circuit board 33. A plurality of connection electrode rows (in this example, five connection electrode rows M1 to M5) are formed side by side at predetermined intervals along the Y-axis direction. Each connection electrode row | line | column M1-M5 has the some connection electrode 34 arranged in parallel by the formation pitch P1 along the X-axis direction. The formation pitch of the connection electrodes 34 in the Y-axis direction may be the same as or different from the formation pitch P1.

FIG. 5 is a top view showing the formation pattern of the pixel electrode 32 superimposed on the structure shown in FIG. In FIG. 5, in order to facilitate the distinction between the connection electrode 34 and the pixel electrode 32, the connection electrode 34 is indicated by a broken line and the pixel electrode 32 is indicated by a solid line. In FIG. 5, the solder bumps 35 formed between the connection electrodes 34 and the pixel electrodes 32 are shown with sand hatching.

  As shown in FIG. 5, a plurality of pixel electrode rows (in this example, two pixel electrode rows L1 and L2) are formed side by side along the Y-axis direction at a predetermined interval. Each pixel electrode row L1, L2 has a plurality of pixel electrodes 32 arranged in parallel at a formation pitch P2 along the X-axis direction. In the example of FIG. 5, each pixel electrode 32 has a square top shape. That is, in each pixel electrode 32, the dimension in the X-axis direction and the dimension in the Y-axis direction are equal to each other. Note that the formation pitch of the pixel electrodes 32 in the Y-axis direction may be the same as or different from the formation pitch P2. In addition, the upper surface shape of the pixel electrode 32 is not necessarily a square, and may be an arbitrary geometric figure such as an arbitrary polygon, a circle, or an ellipse.

  In the example shown in FIGS. 3 and 5, the formation pitch P2 is set to be twice the formation pitch P1. Therefore, as shown in FIG. 5, in this example, each pixel electrode 32 overlaps the four connection electrodes 34 in plan view. That is, each pixel electrode 32 overlaps the four connection electrodes 34 when viewed from the Z-axis direction. Each pixel electrode 32 is physically and electrically connected to four connection electrodes 34 via four solder bumps 35.

  6 is an enlarged view showing a part of the structure shown in FIG. In each pixel 60, the X-ray 50 that has passed through the bias electrode 31 and has been applied to the X-ray conversion film 30 is directly converted into an electrical signal by the X-ray conversion film 30. Specifically, in the direct conversion type X-ray sensor, when the X-ray conversion film 30 is irradiated with the X-rays 50, the charges 51 are excited in the X-ray conversion film 30 according to the irradiated X-ray dose. Further, a predetermined electric field is generated in the X-ray conversion film 30 by the bias voltage applied to the bias electrode 31. The electric charge 51 generated in the X-ray conversion film 30 is attracted to the pixel electrode 32 from the electric charge generation point 61 by the electric field, and between the pixel electrode 32 and the solder bump 35 by the electric field generated in the pixel electrode 32. It is attracted to the charge extraction point 62 which is a contact point. After that, the electric current is taken out from the electric charge extraction point 62 through the solder bump 35 and the connection electrode 34 in this order, and is extracted to the circuit board 33 as an electric current. The current value is converted into a voltage value by a current / voltage conversion circuit (not shown) in the circuit board 33 and output as data.

  FIG. 7 is an enlarged top view showing a part of the structure shown in FIG. In each pixel 60, since the pixel electrode 32 is connected to the four solder bumps 35, there are four charge extraction points 62 in each pixel 60. Therefore, the maximum distance K2 in plan view from the charge generation point to the charge extraction point (that is, the distance from the charge generation point 61 to the charge extraction point 62 in the plane shown in FIG. 7) is in plan view of the pixel 60. Smaller than the maximum dimension K1 (that is, the diagonal length of the pixel 60 in the plane shown in FIG. 7). Specifically, in the example shown in FIG. 7, the maximum distance K2 is 1/4 of the maximum dimension K1.

  FIG. 8 is a top view showing the formation pattern of another pixel electrode 32 superimposed on the structure shown in FIG. Similar to FIG. 5, two pixel electrode rows L1 and L2 are formed side by side along the Y-axis direction at a predetermined interval. Each pixel electrode row L1, L2 has a plurality of pixel electrodes 32 arranged in parallel at a formation pitch P2 along the X-axis direction. Each pixel electrode 32 overlaps the nine connection electrodes 34 in plan view. Specifically, each pixel electrode 32 overlaps the whole of one central connection electrode 34 and a part of each of the eight connection electrodes 34 in the periphery in plan view. Further, the pixel electrode 32 is physically and electrically connected to a single connection electrode 34 through a solder bump 35. As described above, in the example illustrated in FIG. 8, the solder bump 35 is connected to the center portion (including substantially the center) of the pixel electrode 32 in plan view.

  FIG. 9 is an enlarged top view showing a part of the structure shown in FIG. In each pixel 60, the pixel electrode 32 is connected to the solder bump 35 at the center. Therefore, the maximum distance K3 in plan view from the charge generation point to the charge extraction point (that is, the distance from the charge generation point 61 to the charge extraction point 62 in the plane shown in FIG. 9) is in plan view of the pixel 60. Is smaller than the maximum dimension K1 (that is, the diagonal length of the pixel 60 in the plane shown in FIG. 9). Specifically, in the example shown in FIG. 9, the maximum distance K3 is ½ of the maximum dimension K1.

  In the above description, the example in which the formation pitch P2 of the pixel electrodes 32 is set to twice the formation pitch P1 of the connection electrodes 34 has been described, but the present invention is not limited to this example. As long as one pixel electrode 32 can overlap the plurality of connection electrodes 34 in plan view, the ratio of the formation pitch of the pixel electrodes 32 and the formation pitch of the connection electrodes 34 is arbitrary. FIG. 10 is a top view showing the formation pattern of another pixel electrode 32 superimposed on the structure shown in FIG. In the example shown in FIG. 10, the formation pitch P3 of the pixel electrodes 32 is set to 2.5 times the formation pitch P1 of the connection electrodes. In the example shown in FIG. 10, the formation pitch of the pixel electrodes 32 in the Y-axis direction may be the same as or different from the formation pitch P3.

  Thus, according to the X-ray inspection apparatus 1 according to the present embodiment, one pixel electrode 32 overlaps the plurality of connection electrodes 34 in plan view. Therefore, even when the area and the formation pitch of the pixel electrode 32 are different due to different specifications of the conversion unit 20, the connection electrode 34 on which the solder bump 35 is to be formed with the pixel electrode 32 is appropriately selected. Thus, the pixel electrode 32 and the connection electrode 34 can be connected to each other via the solder bump 35. As a result, the common signal processing unit 21 can be used even if the specifications of the conversion unit 20 are different.

  Further, as shown in FIGS. 7 and 9, the maximum distances K2 and K3 in plan view from the charge generation point 61 to the charge extraction point 62 in the pixel 60 are less than the maximum dimension K1 in plan view of the pixel 60. Is set. Therefore, the charge 51 generated in the X-ray conversion film 30 can be taken out to the circuit board 33 through the solder bumps 35 quickly and without applying a high voltage.

  In particular, according to the structure shown in FIGS. 5 and 10, by connecting one pixel electrode 32 to a plurality of connection electrodes 34 via a plurality of solder bumps 35, the maximum distance K2 can be easily reduced to less than the maximum dimension K1. Can be set.

  In particular, according to the structure shown in FIG. 8, the pixel electrode 32 is connected to the connection electrode 34 via the solder bump 35 at a substantially central portion in plan view, so that the maximum distance K3 is less than the maximum dimension K1. It can be set easily. Moreover, the number of solder bumps 35 that connect the pixel electrode 32 and the connection electrode 34 can be reduced as compared with the structure shown in FIGS. As a result, it is possible to suppress the loss of charge proportional to the number of solder bumps 35.

  In the above description, an example of using X-rays for inspection of an article has been described. However, other electromagnetic waves or particle beams having a transmitting action may be used.

DESCRIPTION OF SYMBOLS 1 X-ray inspection apparatus 6 Belt conveyor 7 X-ray irradiation part 8 X-ray detection part 12 Article 20 Conversion part 21 Signal processing part 30 X-ray conversion film 32 Pixel electrode 33 Circuit board 34 Connection electrode 35 Solder bump

Claims (3)

A transport unit for transporting an article to be inspected;
An irradiation unit that irradiates the article being conveyed by the conveyance unit with an electromagnetic wave or particle beam having a transmission effect;
A detection unit for detecting electromagnetic waves or particle beams transmitted through the article,
The detector is
A converter that converts electromagnetic waves or particle beams into electrical signals;
A signal processing unit for processing electrical signals;
The converter is
A conversion film that receives the electromagnetic wave or particle beam that has passed through the article and generates a charge corresponding to the electromagnetic wave or particle beam, thereby directly converting the electromagnetic wave or particle beam into the electrical signal;
A plurality of pixel electrodes in contact with the conversion film,
The signal processing unit
A circuit board on which a circuit for processing the electrical signal is formed;
A plurality of connection electrodes formed on the circuit board and connected to the pixel electrodes via bumps;
The charge generated in the conversion film is taken out from the pixel electrode to the bump,
One pixel electrode overlaps the plurality of connection electrodes in plan view,
An article inspection apparatus in which a maximum distance in a plan view from a charge generation point to a charge extraction point in a pixel is set to be less than a maximum dimension in a plan view of the pixel.   The article inspection apparatus according to claim 1, wherein one pixel electrode is connected to the plurality of connection electrodes via the plurality of bumps.   The article inspection apparatus according to claim 1, wherein the pixel electrode is connected to the connection electrode through the bump at a substantially central portion in plan view.

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