GB2374267A

GB2374267A - Method of determining source and sensor life in x-ray inspection apparatus

Info

Publication number: GB2374267A
Application number: GB0126303A
Authority: GB
Inventors: Masahiro Shimada; Takashi Kabumoto; Hirokazu Satou; Osamu Hirose
Original assignee: Ishida Co Ltd
Current assignee: Ishida Co Ltd
Priority date: 2000-11-07
Filing date: 2001-11-01
Publication date: 2002-10-09
Anticipated expiration: 2021-11-01
Also published as: CN101105464A; CN1356539A; KR20020036705A; KR100830378B1; GB0126303D0; JP2002148211A; CN101105464B; GB2374267B

Abstract

An X-ray inspection apparatus is an apparatus that conducts inspection of articles using X-rays. The apparatus is equipped with an X-ray irradiator, an X-ray line sensor, and a detection level file. The X-ray line sensor detects X-rays from X-ray irradiator. The Detection level file stores the time-based change in the detection level of X-ray line sensor. The change in detection level may then be used to determine or predict the end of the useful life of the source or sensors.

Description

X-RAY INSPECTION APPARATUS

The present invention relates to an X-ray inspection apparatus. More particularly, the present invention relates 5 to an X-ray inspection apparatus that conducts inspection of an article using an X-ray source and an X-ray line sensor. Inspection using an X-ray inspection apparatus is sometimes conducted in production lines for food and other 10 products in order to avoid shipping products that are contaminated with foreign matter or split or chipped. With such an X-ray inspection apparatus, X- rays are applied to each article to be inspected while the articles are transported continuously and an X-ray line sensor detects 15- -- l re- - - - smitted state of the X-rays. In this manner, the apparatus identifies if there are contaminants in the article, if the article is split or chipped, or if the number of units (individual pieces) inside the article is insufficient. Also, some X-ray inspection apparatuses 20 conduct inspection in which the number of units inside the article is counted.

Articles that are identified as defective in the X-ray inspection are separated as defective products by a sorting apparatus at a later stage. When contamination of the 25 article or other dangerous defect is discovered, the production line is stopped and the upstream equipment inspected in order to determine the cause. Meanwhile, when such defects as splitting and chipping and insufficient number occur, the article is often returned to the 30 production line after conducting unit replacement or number adjustment. Also, when the number of units is counted by the X-ray inspection apparatus, a label on which the counted number is printed is attached in a subsequent step.

X-ray inspection apparatuses like that described above 35 use an X-ray source that irradiates X-rays toward the article and an X-ray line sensor that detects the transmitted state of those X-rays. These are expensive

expendable items and conventionally are replaced when the prescribed replacement time recommended by the manufacturer has passed, e.g., 8000 hours for the X-ray source and 20,000 hours for the X-ray line sensor.

5 However, the recommended replacement time recommended by the manufacturer is an estimate and the time when replacement is actually necessary is affected by such factors as the usage conditions, the X-ray transmittance of the articles being inspected, and the ambient atmosphere.

10 Consequently, there are times when the service lives of the X-ray source and X-ray line sensor end before the manufacturer recommended replacement time arrives and there are times when the X-ray source and Xray line sensor can actually still be used even after the manufacturer 15 recommended replacement time has arrived.

Conversely, there are currently in existence X-ray inspection apparatus that display the detection level of the X-ray line sensor on a display device when the apparatus is started up to inform the user whether or not 20 the apparatus can be used. However, even with this kind of apparatus, it is unclear when the apparatus will become unusable and in current practice the user changes the sensor and source when the manufacturer recommended replacement time arrives.

25 The object of the present invention is to provide an X-ray inspection apparatus that prevents the occurrence of a situation in which the X-ray source or X-ray line sensor reaches a state where it cannot withstand use while the X ray inspection apparatus is in the midst of being used.

30 In accordance with the present invention, an X-ray inspection apparatus for conducting inspection of an article using X-rays, comprises an X-ray source for irradiating X-rays; an X-ray line sensor for detecting X rays from said X-ray source; and a memory section for 35 storing the time-based change in the detection level of said X-ray line sensor.

The detection level of the X-ray line sensor normally declines gradually as the X-ray source and X-ray line sensor are consumed. In order to monitor this decline over time, the time-based change in the detection level of the 5 X-ray line sensor is stored in the memory section.

Therefore, the user of the X-ray inspection apparatus can learn the timebased change in the detection level of the X-ray line sensor and replace the X-ray source and X-ray line sensor before they reach a state where they cannot 10 withstand use. As a result, situations in which the service life of the X-ray source or X-ray line sensor ends before the manufacturer recommended replacement time arrives and the apparatus suddenly becomes unusable in the midst of being used are prevented.

15 Furthermore, although it is currently difficult to measure the degree of consumption of the X-ray source and the degree of consumption of the Xray line sensor separately and keep a record of each, if possible it is preferred that the time-based change in the degree of 20 consumption of each be recorded and the user be informed of the appropriate replacement time for both the X-ray source and the X-ray line sensor.

The time-based change in the detection level of the X-

ray line sensor stored in the memory section may also be 25 presented to the user so that the user can estimate the replacement time or fed to a computer that calculates the estimated replacement time and presents the estimate to the user. When an abnormal time-based change occurs, the time-

based change in the detection level may also be used to 30 judge and inform the user of failure instead of consumption. Preferably, the X-ray sensor comprises a plurality of units and the memory section stores the time-based change in the detection level of each of unit of the X-ray line 35 sensor.

When the X-ray line sensor comprises a plurality of units, the service life of each of the plurality of units

may differ depending on differences in such conditions as the quantity of X-rays blocked by the articles being inspected and the distance from the X-ray source.

In view of this situation, the time-based change in 5 detection level of each unit is stored in the memory section. Thus the life of each unit can be estimated and each unit can be replaced at the appropriate replacement time. Conventionally, excluding cases of failure and the like, all units of X-ray line sensors comprising a 10 plurality of units were often replaced simultaneously at the replacement time. However, with this preferred X-ray inspection apparatus, it is possible to successively replace only those units requiring replacement and enjoy an economical merit with respect to replacement of expensive 15 expendable items.

The X-ray inspection apparatus may further include a warning control means. The warning control means monitors the time-based change in the detection level stored in said memory section and issues a warning when the detection 20 level is below a prescribed minimum value.

Since a warning is issued to the user when the detection level goes below the minimum value, the user is provided with an opportunity to consider changing the X-ray source and X-ray line sensor.

25 The prescribed minimum value may be set as an absolute detection value necessary for inspection or a management purpose detection level that allows some leeway before the absolute minimum is reached. It is also acceptable to establish both.

30 The warning control means may estimate an up-coming time-based change based on the time-based change in the detection level and gives notification when it judges that the estimated detection level will go below the minimum value. 35 Based on the time-based change in the detection level stored in the memory section, the warning control means judges if the detection level will go below the minimum

value in the near future (up-coming). When it judges that the detection level will go below the minimum value in the near future, the warning control means notifies the user of that judgment. This notification can be accomplished by any 5 means, such as a buzzer or other alarm or indication on a display. When a display is used, an indication such as "usable for approximately xx more days" or "usable for approximately x more months" or an hour-based indication such as "usable for approximately xx more hours'' may be lo used.

Preferably, the X-ray inspection apparatus further includes a transport mechanism that transports articles.

The memory section additionally stores the time-based change in the transport speed of the transport mechanism.

15 The warning control means additionally monitors the time-

based change of said transport speed stored in said memory section and issues a warning when it judges that the transport speed is abnormal.

Here, the time-based change in the transport speed of 20 the transport mechanism is both stored and monitored and a warning is issued when it is judged that the transport speed is abnormal. Consequently, the user can become aware of the problem earlier when the transport mechanism fails or does not operate in accordance with control.

25 The X-ray inspection apparatus may include a casing and an X-ray leakage quantity sensor. The casing has an opening for carrying in or discharging an article and the X-ray leakage quantity sensor is disposed in the vicinity of the opening on the outside of said casing. The memory 30 section additionally stores the time-based change in the X ray leakage quantity obtained from said X-ray leakage quantity sensor. The warning control means additionally monitors the time-based change in the X-ray leakage amount stored in the memory section and issues a warning when the 35 X-ray leakage quantity exceeds a prescribed value.

Here, the X-ray leakage quantity sensor is disposed close to the opening of the casing and the time-based

change in the X-ray leakage quantity is both stored and monitored. A warning is issued when the X-ray leakage quantity exceeds a prescribed value. As a result the occurrence of X-ray leakage accidents can be prevented.

5 Also, "when the X-ray leakage quantity exceeds a prescribed value" refers to times when the X-ray leakage quantity over a short period of time exceeds a prescribed quantity and times when the cumulative X-ray leakage quantity over a long period of time exceeds a prescribed 10 value.

The X-ray inspection apparatus may in some cases be connected with an external device via the internet.

Also, the warning control means can issue warnings to the external device.

15 A display section may be further provided. The display section is provided for displaying at least one of the time-based changes stored in the memory section.

Some examples of X-ray inspection apparatus according to the present invention will now be described with 20 reference to the accompanying drawings, in which: FIG. 1 is a perspective view of the external appearance of an X-ray inspection apparatus; FIG. 2 is a simple schematic view of inside of the shield box of the X-ray inspection apparatus; 25 FIG. 3 is an illustrative view showing the principles of X-ray inspection; FIG. 4 shows the longitudinal configuration of the X ray inspection apparatus; FIG. 5 is a block diagram of the control computer; 30 FIG. 6 is a screen shot of the LCD monitor; and, FIG. 7 is a screen shot of the LCD monitor.

FIG. 1 shows the external appearance of an X-ray inspection apparatus that embodies the present invention.

This X-ray inspection apparatus 10 is one apparatus that 35 conducts quality inspection in production lines for food products and other products. The apparatus applies X-rays to products that are transported thereto in a continuous

manner and judges if the products are defective based on the quantity of X-rays that pass through the product.

As shown in FIG. 4, product G. which is an article to be inspected by Xray inspection apparatus 10, is carried 5 to X-ray inspection apparatus 10 by front conveyor 60. X-

ray Inspection apparatus 10 judges if product G contains contaminants. The judgment results obtained at X-ray inspection apparatus 10 are sent to a sorting mechanism 70 disposed downstream of X-ray inspection apparatus 10. At 10 sorting mechanism 70, a product G is fed to regular line conveyor 80 when the product G was judged to be good at X-

ray inspection apparatus 10 and a product G is fed to defective part collecting conveyer 90 when the product G is judged to be defective at Xray inspection apparatus 10.

15 As shown in FIGS. 1 and 2, X-ray inspection apparatus 10 comprises chiefly the following: a shield box 11; a conveyor 12; an X-ray irradiator 13; an X-ray line sensor 14; an LCD monitor 30 with touch panel function; an X-ray leakage quantity sensor 40; and a control computer 20 (see 20 FIG. 5).

Shield box 11 has an opening lla on both lateral sides for carrying products in and out. Inside this shield box are housed conveyer 12, X-ray irradiator 13, X-ray line sensor 14, and control computer 20.

25 Although it is not shown in FIG. 1, opening lla is covered with a shielding curtain for preventing X-rays from leaking outside of shield box 11. This shielding curtain is made of rubber that contains lead and is pushed out of the way by the product when the product is carried in and out.

30 Also, in addition to LCD monitor 30, the key hole and power switch are disposed on the upper part of the front surface of shield box 11.

Conveyer 12 serves to transport articles to be inspected into shield box 11 and is driven by conveyer 35 motor 12a shown in FIG. 5. Invertercontrol of conveyer motor 12a by control computer 20 allows the transport speed

of conveyer 12 to be controlled precisely so as to match the setting speed inputted by the user.

As shown in FIG. 2, X-ray irradiator 13 is disposed above conveyer 12 and emits fan-shaped X-rays toward the X-

5 ray line sensor below (see shaded region X in FIG. 2).

X-ray line sensor 14 is disposed below conveyer 12 and detects the X-rays transmitted through product G and conveyer 12. As shown in FIG. 3, X-ray line sensor 14 comprises eight units 51-58 arranged in a row. Each unit 10 has many pixels 14a arranged in a straight line in a direction perpendicular to the transport direction of conveyer 12.

LCD monitor 30 is a full-dot liquid crystal display.

LCD monitor 30 also has a touch panel function and serves 15 to display screens requesting parameter input and the like regarding initial settings and defect judgment.

X-ray leak quantity sensors 40 always indicate the dose equivalent rate and are mounted in the vicinity of both openings lla of shield box 11, as shown in FIGS. 1 and 20 4. Since X-ray quantity sensors 40 always indicate the quantity of leaked X-rays, those who work close to X-ray inspection apparatus 10 can obtain peace of mind.

AS shown in FIG. 5, control computer 20 is installed with the following: a CPU 21; main memory sections ROM22 25 and RAM 23 controlled by CPU 21; and an HDD (hard disk) 25.

Control computer 20 also has an FDD (floppy disk drive) 24 for inputting from and outputting to a floppy disk.

Furthermore, computer 20 is also equipped with a display control circuit that controls the display of data 30 on LCD monitor 30, a key input circuit that fetches key input data from the touch panel of LCD monitor 30, and an I/O port for controlling data printing of a printer (not shown) . CPU 21, ROM 2 2, RAM 23, FDD 24, and ADD 2 5 are 3 5 connected together through a bus line, such as an address bus or a data bus.

Control computer 20 is connected to conveyer motor 12a, rotary encoder 12b, photoelectric sensor 15, X-ray irradiator 13, X-ray line sensor 14, and X-ray leakage quantity sensor 40.

5 Mounted to conveyer motor 12a, rotary encoder 12b detects the transport speed of conveyer 12 and sends it to control computer 20. This transport speed data is stored and collected in transport speed file 25c inside HAD 25 at prescribed time intervals.

10 Photoelectric sensor 15 is a synchronous sensor for detecting the timing at which product G (the article to be inspected) reaches the position of X-ray line sensor 14 and comprises a light projecting device and a light receiving device disposed so as to sandwich the conveyer.

15 The X-ray leakage quantity data detected by X-ray leakage quantity sensors 40 are acquired by control computer 20 at prescribed time intervals and stored/collected in X-ray leakage quantity file 25b inside HOD 25.

20 Control computer 20 receives a signal from photoelectric sensor 15 and acquires X-ray fluoroscopic image signals (see FIG. 3) at narrow time intervals from X ray line sensor 14 when product G pass through the fan shaped X-ray emission section (see FIG. 2). An X-ray image 25 of product G is generated based on these X-ray fluoroscopic image signals.

Control computer 20 then uses the obtained X-ray image to judge if the article is good or defective based on a plurality of judgment methods, e. g., trace detection, 30 binarized detection, and mask binarized detection. Product G is judged to be defective if the judgment result obtained from even one of the judgment methods is a judgment of defectiveness. Trace detection and binarized detection are used to 35 judge regions where the image is not masked. Meanwhile, mask binarized detection is used to judge regions where the

image is masked. The mask is established with respect to the container portion, etc., of product G. In the trace detection method, a reference level (threshold value) along the approximate thickness of the 5 object to be inspected is established and the product G is judged to contain contaminants when the image is darker than the reference level. This method can detect relatively small contaminants.

In the binarized detection and mask binarized 10 detection methods, the reference level is set to a fixed brightness and the product G is judged to contain contaminants when the image is darker than the reference level. The binarized detection method is established for detecting relatively large contaminants.

15 The user can set and change the reference level and mask region for each judgment method by inputting data using the touch panel function of LCD monitor 30.

During normal inspection, control computer 20 displays the obtained X-ray image of product G and information 20 regarding the judgments obtained from each of the judgment methods on LCD monitor 30.

Next, the diagnostic function of the X-ray inspection level that estimates the replacement time of X-ray irradiator 13 and X-ray line sensor 14 will be described.

25 When the power to X-ray inspection apparatus 10 is turned on or when Xray detection level diagnostic mode is selected, control computer 20 conducts a diagnostic test of the X-ray detection level. In this diagnostic test, a dark level measurement in which the detection level (dark level) 30 of X-ray line sensor 14 is measured while X-rays are not being emitted from X-ray irradiator 13 and a bright level measurement in which the detection level (bright level) of X-ray line sensor 14 is measured while X-rays are being emitted from X-ray irradiator 13 and nothing is placed on 35 conveyer 12. The data are stored/collected in detection level file 25a inside HDD 25. Data for the difference between the bright level and dark level (hereafter called

election level are also stored/collected in detection level file 25a. In short, the time-based change in the bright level, dark level, and detection level are stored in detection level file 25a.

5 The data for each of these levels are stored with respect to each unit 51-58 of X-ray line sensor 14.

Normally the power supply of X-ray inspection lo apparatus is turned on at least once every few days, so it is believed that a long period in which the aforementioned 10 diagnostic test is not conducted will not occur. However, in order to prevent such a situation, it is acceptable, for example, to automatically display a message on LCD monitor 30 every 24 hours urging the user to switch over to X-ray detection level diagnostic mode.

15 After completing the aforementioned diagnostic test, control computer 20 displays the screen shown in FIG. 6 on LCD monitor 30. In addition to current numerical values for each level, the screen shows the remaining usable time and a graph of the time-based change in each level. The 20 remaining usable time is the amount time until the anticipated point in time when the detection level will fall below a prescribed minimum value and is calculated by control computer 20 based on past time-based changes in the detection level.

25 When the current detection level is judged to be below the prescribed minimum value during the calculation of the remaining usable time by control computer 20 after the diagnostic test, control computer 20 conducts a warning indication using LCD monitor 30 (see FIG. 7). Here, the 30 warning arning: X-ray Inspection Not Possible is displayed with large characters to inform the user that X-ray inspection apparatus lo cannot be used unless X-ray irradiator 13 or X-ray line sensor 14 is replaced.

Also, although not shown, a message urging replacement 35 of X-ray irradiator 13 or X-ray line sensor 14 is displayed when the remaining usable time has fallen below the management-purpose minimum value (e.g., 20 hours).

The diagnostic results shown in FIGS. 6 and 7 and on the warning screen are the worst results among the eight units 51 to 58. By adjusting the initial settings, the results for each of the units can be displayed in order on 5 LCD monitor 30.

Next, the control for discovering a failure of conveyer 12 is explained.

As previously described, transport speed data for conveyer 12 sent from rotary encoder 12b (which is mounted 10 to conveyer motor 12a) is stored/collected in transport speed file 25c inside HDD 25 at prescribed time intervals.

More specifically, actual transport speed data for conveyer 12 is stored along with the transport speed set by the user. 15 Control computer 20 monitors the absolute value or deviation value of the difference between the actual transport speed and the set transport speed and issues a warning display on LCD monitor 30 when the aforementioned difference is larger than a prescribed threshold value.

20 Also, when the user requests transport speed related data to be displayed during maintenance mode, etc., control computer 20 displays the time-based change of each data as a graph o LCD monitor 30.

Also, when the difference between the actual transport 25 speed and the set transport speed is gradually becoming larger, control computer 20 displays that fact on LCD monitor 30 and urges caution.

As a result, the user can become aware of the problem earlier when conveyer 12 or conveyer motor 12a fails or 30 does not operate in accordance with control.

Next, control for displaying the quantity of X-rays that has leaked from opening lla of shield box 11 of X-ray inspection apparatus 10 is explained.

As previously explained, control computer 20 acquires 35 the X-ray leakage quantity data detected by X-ray leakage quantity sensors 40 at prescribed time intervals and

stores/collects the data in X-ray leakage quantity file 25b inside HAD 25.

Control computer 20 calculates the cumulative quantity of leaked X-rays based on the X-ray leakage quantity data 5 collected in X-ray leakage file 25b. When this cumulative quantity exceeds a prescribed quantity, the control computer displays information regarding when the cumulative value came to exceed what numerical value on LCD monitor 30. 10 The detection level of X-ray line sensor 14 normally declines gradually as X- ray irradiator 13 and X-ray line sensor 14 are consumed. In the X-ray inspection apparatus 10 of the present embodiment, the time-based change in the detection level of X-ray line sensor 14 is stored/collected 15 in detection level file 25a of HDD 25 so that the time-

based change in the aforementioned decline can be monitored. Consequently, the user of X-ray inspection apparatus 10 can learn the time-based change in the detection level 20 of X-ray line sensor 14 by means of a screen display like that shown in FIG. 6 and can be expected to replace X- ray irradiator 13 and X-ray line sensor 14 before they become unable to withstand use. Therefore, there will be little occurrence of such trouble as the service life of X-ray 25 irradiator 13 or X-ray line sensor 14 ending before the manufacturer recommended replacement time arrives and X-

ray inspection apparatus 10 suddenly becoming unusable while in the midst of being used.

For example, a user who saw the warning screen shown 30 in FIG. 7 would recognize that X-ray irradiator 13 and X-

ray line sensor 14, whose use started at the same time, have both been used 9211 hours and at least one of them must be replaced. Normally, the user would then replace X-

ray irradiator 13 first because X-ray irradiator 13 has a 35 shorter service life than X-ray line sensor 14 the manufacturer instruction manual also describes a standard for the recommended replacement time. After replacing the

X-ray irradiator, the user uses the touch panel function of LCD monitor 30 and resets the time used to 0 for X-ray irradiator 13. If this is done, at the next replacement time the user can check the cumulative usage time of both 5 the X-ray irradiator 13 and the X-ray line sensor 14 and determine which should be replaced.

In X-ray inspection apparatus 10 of the present embodiment, X-ray line sensor 14 comprises plurality of units 51 to 58. As shown in FIGS. 2 and 3, units 51 to 58 10 each have a different quantity of X-rays obstructed by product G. which is the target of the inspection, and a different distance from X-ray irradiator 13. Consequently units 51 to 58 each have a different service life.

In view of this fact, here the time-based change in 15 detection level for each unit 51-58 is stored in detection level file 25a. The apparatus is configured such that the diagnostic results for the X-ray detection level of each unit 51-58 can be displayed on LCD monitor 30.

Consequently, it is possible to estimate the service 20 life of each unit 51-58 and to replace units 51-58 individually at the appropriate replacement time. This allows one to successively replace only those units requiring replacement and enjoy an economical merit with respect to replacement of expensive expendable items (X-ray 25 line sensor 14).

In the previously described embodiment, a warning is displayed on LCD monitor 30 when it is judged that the current detection level is below a prescribed minimum value. However, it is also effective to issue an alarm with 30 a buzzer or the like as well.

In the previously described embodiment, X-ray inspection apparatus 10 was described as chiefly detecting contamination defects. However, the present invention can also be applied to X-ray inspection apparatuses for 35 detecting splitting/chipping defects and X-ray inspection apparatuses that can count the pieces inside a product

having a plurality of pieces disposed in a planar arrangement. In the previously described embodiment, the worst among units 51 to 58 was displayed on LCD monitor 30.

5 However, it is also acceptable to display all of units 51 to 58, the transport speed data for conveyer 12, and the X-

ray leakage quantity on LCD monitor 30 simultaneously. It is also acceptable to select and display only warning-

related data or to display only warning-related data in a 10 different color. When all of units 51 to 58 are displayed, the time-based change of each unit can be compared, making it easy to pinpoint units whose consumption is severe.

Although it is currently difficult to determine the degree of consumption of X-ray irradiator 13 and the degree 15 of consumption of X-ray line sensor 14 separately, if possible this becomes possible in the future then the degree of consumption of each can be determined from the time- based change in the bright level and dark level and the user be informed of the appropriate replacement time 20 for both X-ray irradiator 13 and X- ray line sensor 14. It is also possible to connect X-ray inspection apparatus 10 of the

previously described embodiment to a web server and send information to a web browser on an information terminal in a location remote from X-ray 25 inspection apparatus 10. For example, when a warning screen like that shown in FIG. 7 is displayed, a warning e-mail might be sent simultaneously to an external information terminal device through a web server. Information (e.g., part numbers) that makes it possible to order X-ray 30 irradiator 13 and X-ray line sensor 14 of X-ray inspection apparatus 10 might also be included in the content of the email. Thus the information terminal device and X-ray inspection apparatus 10 can be linked via the internet 35 without using a dedicated communication circuit and X-ray inspection apparatus 10 can be managed relatively easily from a remote location.

Claims

1. An X-ray inspection apparatus for conducting inspection of an article using X-rays, comprising: 5 an X-ray source for irradiating X-rays; an Xray line sensor for detecting X-rays from said X ray source; and a memory section for storing the time-based change in the detection level of said X-ray line sensor.

10

2. An X-ray inspection apparatus as recited in claim 1, wherein said Xray sensor comprises a plurality of units, and said memory section stores the time-based change in the detection level of each of said units.

15

3. An X-ray inspection apparatus as recited in claim 1 or claim 2, further comprising a warning control means for monitoring the time-based change in said detection level stored in said memory section, said warning control means issuing a warning when said detection level is below a 20 prescribed minimum value.

4. An X-ray inspection apparatus as recited in claim 3, wherein said warning control means estimates an approaching time-based change based on the time-based change in said detection level and gives notification when it judges that 25 said estimated detection level will go below said minimum value.

5. An X-ray inspection apparatus as recited in claim 3 or claim 4, further comprising a transport mechanism transporting articles, wherein 30 said memory section furthermore stores the time-based change in the transport speed of said transport mechanism, and said warning control means furthermore monitors the time-based change of said transport speed stored in said 35 memory section and issues a warning when it judges that said transport speed is abnormal.

6. An X-ray inspection apparatus as recited in any one of claims 3 to 5, further comprising a casing having an opening for carrying in or discharging an article, and 5 an X-ray leakage quantity sensor disposed in the vicinity of said opening on the outside of said casing, wherein said memory section furthermore stores the time-based change in the X-ray leakage quantity obtained from said X 10 ray leakage quantity sensor, and said warning control means furthermore monitors the time-based change in said X-ray leakage amount stored in said memory section and issues a warning when said X-ray leakage quantity exceeds a prescribed value.

15

7. An X-ray inspection apparatus as recited in any one of claims 3 to 6, wherein said X-ray inspection apparatus is able to connect with an external device via the internet, and said warning control means is able to issue said 20 warnings to said external device.

8. An X-ray inspection apparatus as recited in any one of claims 1 to 7, further comprising a display section for displaying at least one of said changes over time stored in said memory section.

25

9. An X-ray inspection apparatus substantially as hereinbefore described with reference to any of the examples shown in the accompanying drawings.