JP4908852B2 - X-ray inspection equipment - Google Patents

Description

  The present invention relates to an X-ray inspection apparatus that performs inspection by irradiating an article being conveyed with an X-ray from an X-ray source that applies a high voltage between a cathode and an anode to irradiate the X-ray.

  In order to inspect the presence or absence of foreign matter in an article in the manufacturing process of foods, etc., X-rays from an X-ray source are irradiated to the article being conveyed, and X-rays transmitted through the article are received by an X-ray detector. An X-ray inspection apparatus for inspecting an article by performing image processing is installed. In order to perform highly accurate detection with such an X-ray inspection apparatus, the higher the output from the X-ray source, the better. However, the X-ray source has a high output between the cathode (cathode) and the anode (target). When a voltage is applied and electrons emitted from the cathode collide with the anode to output X-rays, the anode is heated to a high temperature that turns red.

Therefore, the insulating oil for cooling sealed in the X-ray source is rapidly deteriorated, and naturally, the anode itself is also greatly deteriorated. Therefore, the X-ray source needs to be periodically replaced. In particular, when cooling or the like is insufficient, the replacement time of the X-ray source is extremely short, and there is a problem that an expensive X-ray source must be frequently replaced. To solve this problem, an X-ray inspection is provided with an X-ray source in which the end of the anode is connected to the housing via a heat conductive electrical insulator to increase the cooling efficiency and thereby extend the life. An apparatus has been proposed (see, for example, Patent Document 1).
JP-A-6-251735

  However, since the X-ray inspection apparatus continues to irradiate X-rays during the operation time during which the inspection is performed, the effect of extending the life of the X-ray source is limited. Therefore, when X-ray irradiation is unnecessary (for example, when the conveyance of an article to be inspected is interrupted), X-ray irradiation is stopped, but energization to the X-ray source is completely stopped. Thereafter, it takes a considerable time from the re-energization until the output of the X-ray source is stabilized, and there is a problem that the inspection cannot be resumed promptly.

  In view of such circumstances, the present invention provides an X-ray inspection apparatus that inspects an article being conveyed by irradiating an X-ray from an X-ray source that irradiates the X-ray by applying a high voltage between the cathode and the anode. An object of the present invention is to provide means capable of extending the life of the X-ray source while ensuring the output stability of the X-ray source.

The invention according to claim 1 includes an X-ray source that irradiates X-rays by applying a high voltage between the cathode and the anode, and irradiates the article being conveyed with the X-rays from the X-ray source. An X-ray inspection apparatus that inspects an article by receiving X-rays that pass through an X-ray detector and performing image processing,
Article detection means for detecting the conveyance state of the article;
Determining means for determining that the article is not in the X-ray detection region of the X-ray detector when the article detection means does not detect the article delivery for a predetermined time or more ;
A controller that reduces the applied current and / or applied voltage without completely stopping energization of the X-ray source based on the determination of the determination means;
An X-ray inspection apparatus is provided.

Invention of Claim 2 is X-ray inspection apparatus of Claim 1, Comprising:
The controller provides an X-ray inspection apparatus that reduces only the applied current while keeping the applied voltage of the X-ray source constant.

Invention of Claim 3 is X-ray inspection apparatus of Claim 2, Comprising:
The applied voltage is set to a predetermined value or more in a voltage range in which X-rays can be irradiated. An X-ray inspection apparatus is provided.

Invention of Claim 4 is an X-ray inspection apparatus in any one of Claims 1 thru | or 3, Comprising:
The control unit provides an X-ray inspection apparatus that reduces application of a heater of an X-ray source based on the determination by the determination unit.

  According to the X-ray inspection apparatus of the first aspect of the present invention, the following excellent effects can be obtained. Since the application of the X-ray source is reduced based on the determination by the determination means that determines that the article is not in the X-ray detection region, the time during which the anode is heated unnecessarily at a high temperature is shortened. Thereby, deterioration of the anode and the cooling oil for cooling the anode can be prevented, and the life of the X-ray source can be extended. In addition, compared with the case where the energization to the X-ray source is completely stopped, the time from the application amount increase to the output stabilization is shortened, so that the inspection can be restarted promptly.

  According to the X-ray inspection apparatus of the second aspect of the present invention, in addition to the effect exhibited by the X-ray inspection apparatus of the first aspect, the following excellent effects are exhibited. When the voltage is a control target, it is necessary to gradually increase the application amount over time until the voltage changes from a low voltage to a high voltage in order to prevent abnormal discharge. On the other hand, when current is controlled as in this claim, abnormal discharge is unlikely to occur, so there is no problem even if the current is increased at a high speed. The inspection state can be quickly switched. Therefore, when it is determined that the article is not in the X-ray detection region, it can be quickly stopped, and when the article is detected, the inspection can be restarted promptly.

  According to the X-ray inspection apparatus of the third aspect of the present invention, in addition to the effects exhibited by the X-ray inspection apparatus of the second aspect, the following excellent effects can be obtained. When the X-ray source is driven in a low voltage region, the X-ray source cathode must be maintained at a high temperature in order to resume the X-ray irradiation with good response. Or deterioration of the cooling oil is accelerated. On the other hand, if it is driven in a high voltage region as in the present claim, the heating temperature by the heater can be lowered, so that deterioration of the cooling oil can be prevented and the life of the heater itself can be extended. Can also be achieved.

  According to the X-ray inspection apparatus of the fourth aspect of the present invention, in addition to the effects exhibited by the X-ray inspection apparatus of any one of the first to third aspects, the following excellent effects are achieved. Since unnecessary heating of the heater is eliminated, it is possible to prevent the heater itself from deteriorating and to prevent the cooling oil from deteriorating due to a decrease in the amount of heat generated by the heater, thereby extending the life of the X-ray source.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Here, FIG. 1 is a front view of an X-ray inspection apparatus 1 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of an X-ray source 2 provided in the X-ray inspection apparatus 1.

(Configuration of X-ray inspection apparatus 1)
The X-ray inspection apparatus 1 irradiates an article being transported with X-rays from an X-ray source 2, receives X-rays that pass through the article with an X-ray detector 3, and performs image processing (foreign matter). As shown in FIG. 1, an X-ray source 2 and an X-ray detector 3 are provided above and below the conveyance surface R of the article, and these X-rays are exposed to the outside. It is provided in the housing 4 that is blocked so as not to leak. Two main body doors 41 that are opened in a horizontal direction around the support shaft 41a as a rotation center so that the inside of the housing 4 can be cleaned and inspected on the side front side (front side in FIG. 1) of the housing 4. 41 is provided. An interlock switch 42 that stops X-ray irradiation from the X-ray source 2 when at least one of the main body doors 41, 41 is not closed is provided in the housing 4 corresponding to each main body door 41. .

  The casing 4 has an inlet 4a and an outlet 4b through which the article passes through the inside of the X-ray inspection apparatus 1 is formed on the left and right sides of the side. The conveying means 5 is set. The transport means 5 is a belt conveyor having a transport surface R for carrying articles continuously carried from the upstream process and passing through an X-ray detection region by the X-ray detector 3. The casters 51... 51 can be pulled out from the X-ray detection area. Inside the entrance 4a and the exit 4b, a plurality of X-ray leakage prevention curtains 43, 43 are detachably attached to a curtain support 44 fixed to the housing 4.

  In the vicinity of the entrance 4a, a photoelectric sensor 6 is provided as an article detection means for detecting the conveyance state of the article, in particular, that the article has been carried into the inlet 4a from the upstream process. Further, the X-ray inspection apparatus 1 receives a detection signal output from the photoelectric sensor 6 and determines that the article is not in the X-ray detection area (FIG. 2), and the article is in the X-ray detection area. A control unit 8 is provided that switches from the normal mode (inspection state) to the power save mode (resting state) that reduces the application of the X-ray source 2 based on the determination by the determination means 7 that is not within. The determination means 7 receives the detection signal from the photoelectric sensor 6 and, after a predetermined time has elapsed, when a state in which a new detection signal cannot be received continues, that is, when an article is carried in from an upstream process for a predetermined time or more. When the interruption occurs, it is determined that “the article is not in the X-ray detection region”.

  As shown in FIG. 2, the X-ray source 2 includes an anode 21 (target) and a cathode 22 (cathode) provided in the vacuum glass tube 20, and a heater that auxiliaryly heats the cathode 22 to a temperature at which X-rays can be emitted. As a filament 23, a constant voltage current circuit 24 and a DC power supply circuit 25 for applying a high voltage between the two electrodes, and a filament circuit 26 for supplying power to the filament 23, together with an insulating cooling oil 27, X It is enclosed in a case 28 having a line transmission window 281. By applying a high voltage between the anode 21 and the cathode 22, electrons emitted from the heated cathode 22 collide with the anode 21, and X-rays are output from the X-ray transmission window 281. Since the conversion efficiency to X-rays is very low and the anode 21 reaches a high temperature that makes it red, the application to the X-ray source is reduced when it is determined that the article is not in the X-ray detection region as described above. In addition, the case 28 is provided with cooling fins 29 as an aid for efficiently releasing heat.

  The constant voltage current circuit 24 is a circuit that can increase or decrease only the applied current while keeping the applied voltage of the X-ray source 2 constant under the control of the control unit 8 based on the determination of the determining means 7. Normal mode (applied voltage 50 kV to 100 kV, applied current 1 mA to 5 mA) and power save mode (applied voltage 50 kV to 100 kV, applied current 0.1 mA to 0.2 mA) depending on whether or not it is within the line detection region Between each other can be switched. Therefore, when the article carried into the X-ray inspection apparatus 1 is interrupted and it is determined that the article is not in the X-ray detection region, the X-ray source 2 is automatically switched to the power saving mode for reducing the applied current. , It becomes a dormant state where no X-rays are irradiated. Further, when the carrying-in of the article is resumed and it is determined that the article is in the X-ray detection region, the mode is switched to the normal mode in which the applied current is increased, and the inspection state in which the X-rays are irradiated is returned.

  The X-ray source 2 can irradiate X-rays even when the applied voltage is set to a voltage lower than the applied voltage range in the normal mode (for example, 45 kV), but the X-ray source 2 is driven in the low voltage region. In order to resume the X-ray irradiation with good response in the case of the heat treatment, the cathode 22 must be kept at a high temperature, and there is a concern that the filament 23 itself is thermally deteriorated or the cooling oil 27 is deteriorated due to the heating of the filament 23. . Therefore, as described above, the heating temperature by the filament 23 is kept low by setting the applied voltage in the normal mode of the X-ray source 2 to a predetermined value or more in the voltage range in which X-ray irradiation is possible.

(Operation of X-ray inspection apparatus 1)
When the X-ray inspection apparatus 1 detects the carry-in of the article by the photoelectric sensor 6 and the judging means 7 judges that there is an article in the X-ray detection area, for example, as shown in the area A of FIG. The normal mode in which the applied voltage of 50 kV and the applied current of 1 mA are applied to the X-ray source 2 is maintained. As a result, the X-ray inspection apparatus 1 irradiates the article being conveyed from the X-ray source 2, receives the X-ray transmitted through the article by the X-ray detector 3, and performs image processing to perform the foreign substance contamination inspection. This is a test state that can be performed.

  Further, the X-ray inspection apparatus 1 detects that no article is carried in by the photoelectric sensor 6 for a predetermined time or more and the judging means 7 judges that there is no article in the X-ray detection area. As shown in the region, the mode is switched to the power saving mode in which only the applied current is reduced to 0.1 mA while the applied voltage to the X-ray source 2 is kept at 50 kV. As a result, the X-ray inspection apparatus 1 stops the X-ray irradiation from the X-ray source 2 to the article being conveyed, and enters a dormant state where the article is not inspected. When the photoelectric sensor 6 detects the carry-in of the article again, as shown in the area C of FIG. 3, the inspection is resumed by returning to the normal mode with the applied current of 1 mA.

(Features of X-ray inspection apparatus 1)
Since the X-ray inspection apparatus 1 is configured as described above, it has the following characteristic points. First, since the application to the X-ray source 2 is reduced based on the determination of the determination means 7 that determines that the article is not in the X-ray detection region, the time during which the anode 21 is heated unnecessarily at a high temperature is short. Become. Thereby, deterioration of the anode 21 and the cooling oil 27 for cooling the anode 21 can be prevented, and the life of the X-ray source 2 can be extended. In addition, compared with the case where the energization to the X-ray source 2 is completely stopped, the time from the application amount increase to the output stabilization is shortened, so that the inspection can be restored in a short time. In the case of sequentially inspecting a plurality of articles by sequentially irradiating the articles continuously carried in from the upstream process and continuously inspecting a plurality of articles as in the present embodiment, the inspection is promptly performed after detecting the resumption of the carry-in of the articles. Can be resumed.

Second, because the applied current is controlled, abnormal discharge is unlikely to occur, and there is no problem even if the current is increased at high speed when the inspection is resumed. As a result, the power save mode and the normal mode with reduced applied amount Can be switched promptly. In addition, when there is a break in the articles that are continuously carried in from the upstream process, the X-ray irradiation can be stopped immediately and the heating time of the X-ray source can be shortened reliably. Since the inspection state capable of X-ray irradiation can be promptly restored even when the operation is resumed, it is particularly suitable for continuous inspection for sequentially inspecting articles that are continuously carried in. Since the output S of the X-ray source 2 is expressed by V ² × I × K (S: output V: applied voltage I: applied current K: constant), the applied voltage V may be reduced. When the voltage is a control target, it is necessary to gradually increase the application amount over time until the voltage changes from a low voltage to a high voltage in order to prevent abnormal discharge. In addition, since the square value of the voltage acts on the output and has a large influence on the output fluctuation, it takes time from the increase in the applied amount to the stabilization of the output.

  Third, since the X-ray source 2 is driven in a high voltage region that is equal to or higher than a predetermined value in the range of applied voltage that can be irradiated with X-rays, the heating temperature by the filament 23 can be lowered, and as a result. In addition to preventing the filament 23 itself from being deteriorated, it is possible to prevent the cooling oil 27 from being deteriorated.

(Modification of the above embodiment)
In the above embodiment, the control unit 8 reduces only the applied current while keeping the applied voltage constant in order to reduce the application of the X-ray source 2, but prevents the X-ray source 2 from being deteriorated by heating. In addition, as a method that can realize a pause state in which the inspection can be restarted promptly, means for reducing only the applied voltage or reducing both the applied voltage and the applied current may be employed.

  In the above embodiment, the control unit 8 performs only the control for reducing the application of the X-ray source 2 when there is no article in the X-ray detection region. However, when the X-ray is not irradiated, it is necessary to heat the cathode 22. Therefore, the application of the filament 23 may be reduced together with the application reduction of the X-ray source 2. As a result, it is possible to prevent the filament 23 itself from being deteriorated due to useless heating and the cooling oil 27 from being deteriorated due to the heat from the filament 23. As a result, the X-ray source 2 can be further extended in life. Further, when there is no article in the X-ray detection region, the conveying means 5 may be stopped together with the application reduction of the X-ray source 2. Thereby, only when an article is carried in from an upstream process and an inspection is performed, the transport means 5 is operated, so that useless energy consumption is prevented.

  In addition, the X-ray inspection apparatus of the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention.

1 is a front view of an X-ray inspection apparatus according to an embodiment of the present invention. Sectional drawing of the X-ray source 2 with which an X-ray inspection apparatus is equipped. The figure explaining the action | operation of an X-ray inspection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray inspection apparatus 2 X-ray source 3 X-ray detector 5 Conveyance means 6 Photoelectric sensor (article detection means)
7 Judgment means 8 Control unit 20 Vacuum glass tube 21 Anode 22 Cathode 23 Filament (heater)
24 Constant Voltage Current Circuit 25 DC Power Supply Circuit 26 Filament Circuit 27 Cooling Oil 28 Case

Claims (4)

An X-ray source that irradiates X-rays by applying a high voltage between the cathode and the anode,
An X-ray inspection apparatus that inspects an article by irradiating an article being conveyed with X-rays from the X-ray source, receiving X-rays transmitted through the article with an X-ray detector, and performing image processing. ,
Article detection means for detecting the conveyance state of the article;
Determining means for determining that the article is not in the X-ray detection region of the X-ray detector when the article detection means does not detect the article delivery for a predetermined time or more ;
A controller that reduces the applied current and / or applied voltage without completely stopping energization of the X-ray source based on the determination of the determination means;
An X-ray inspection apparatus comprising: The X-ray inspection apparatus according to claim 1,
The X-ray inspection apparatus, wherein the controller reduces only the applied current while keeping the applied voltage of the X-ray source constant. The X-ray inspection apparatus according to claim 2,
The X-ray inspection apparatus, wherein the applied voltage is set to a predetermined value or more in a voltage range in which X-rays can be irradiated. The X-ray inspection apparatus according to any one of claims 1 to 3,
The X-ray inspection apparatus characterized in that the control unit reduces the application of the heater of the X-ray source based on the determination by the determination means.

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