JP2007093501A - Data sampling system of x-ray inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data sampling system of an X-ray inspection device that has high inspection efficiency and can shorten the inspection time, even when there are very large number of channels in use. <P>SOLUTION: The data sampling system of the X-ray inspection device irradiates X-rays 3 to an inspected object 1 and inspects the inspected object, based on the intensity of the transmitted X-rays. The data sampling system comprises a linear irradiating device 14 for linearly irradiating predetermined X-rays to the inspected object, a linear detector 16 of many channels for detecting the intensity distribution of the linear X-rays having transmitted the inspected object, an X-ray sensor substrate 22 for simultaneously A/D-converting and outputting the detected signals of the linear detector, without changing-over the channels, and a sensor timing IF substrate 24 for transmitting the sensor values of all the channels received from the X-ray sensor substrate, to a frame grabber substrate 26. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a data collection system of an X-ray inspection apparatus that can simultaneously collect data even when the number of used channels is large and can perform inspection in a short time.

Conventionally, X-ray inspection equipment that detects X-ray intensity distribution of transmitted X-rays and detects internal dangerous objects (firearms, etc.) in inspection of baggage at customs and airports has been widely used. It has been.
In recent years, X-ray inspection apparatuses that can identify not only metals such as firearms but also dangerous materials such as explosives and poisons are known (for example, Non-Patent Document 1).

  The X-ray inspection apparatus of Non-Patent Document 1 uses, for example, two types of pulse X-rays of 75 kVp and 150 kVp. To identify.

  The inspection object targeted by the above-described X-ray inspection apparatus tends to increase in size in order to increase inspection efficiency and shorten inspection time. For example, an apparatus having a frontage exceeding 2000 mm or a marine container is inspected for each container. In recent years, devices have been demanded.

  Although not an X-ray inspection apparatus, for example, Patent Documents 1 to 3 have already been disclosed as related prior art.

L-3 Communications Security and Detection Systems, Automated Screening Systems, Internet <URL: http: // www. dsxray. com / ProductCategoryDetails. asp? CatID = 7>

Japanese Patent No. 3157435, “Data Acquisition System Using Delta-Sigma Analog-to-Digital Signal Converter” Japanese Translation of PCT International Publication No. 2004-5103835, “Digital-to-Analog Converter Using Sigma-Delta Loop and Feedback DAC Model” JP-T-2003-500083, “Improved data collection system for generating accurate projection data in CT scanner”

  In the conventional data acquisition system of the X-ray inspection apparatus, for example, as disclosed in FIG. 2 of Patent Document 1, the same number of detectors that generate about 350 to 1000 signals through the same number of channels are used. The output of each detector is input to an analog multiplexer via an independent preamplifier and analog filter, time-shared by this analog multiplexer, input to a common A / D converter, and the digitized data is converted into digital data It was designed to output via a multiplexer.

  However, in the conventional system described above, the conversion speed is slow due to the switching of the common A / D converter (for example, around 1 μsec sampling period), and the large number of channels used (for example, 2000 to 5000) is a large X-ray inspection. When applied to the apparatus, only one (1 line) AD conversion required 2 to 5 msec even for switching. Therefore, in the case of a large object to be inspected, there is a problem that the inspection efficiency is low and the inspection time cannot be shortened.

  In addition, when a large object is to be inspected, the thickness of the object to be inspected also increases, so that the X-ray source to be irradiated needs to be increased in energy (for example, 3 to 9 MeV). The source is pulsed irradiation. However, the conventional data acquisition system cannot cope with pulsed X-rays.

  Furthermore, in the case of a large inspected object, since the material and thickness of the inspected object are also wide, especially when different materials overlap, for example, when drugs etc. are hidden between thick iron plates, Its detection was difficult.

The present invention has been developed to solve the above-described problems. That is, a first object of the present invention is to provide a data collection system for an X-ray inspection apparatus that has high inspection efficiency and can shorten inspection time even when the number of used channels is very large (for example, 2000 to 5000). is there.
A second object is to provide a data collection system for an X-ray inspection apparatus that can handle even high-energy pulse irradiation.
Furthermore, the third object is to obtain a data collection system for an X-ray inspection apparatus capable of detecting each of the objects to be inspected even if they have a wide range of materials and thicknesses and even if different materials overlap. Is to provide.

According to the present invention, there is provided a data collection system for an X-ray inspection apparatus that inspects an inspection object from the intensity of X-rays that have been irradiated and transmitted through the X-ray.
A linear irradiation apparatus that linearly irradiates a target object with predetermined X-rays;
A multi-channel linear detector for detecting the intensity distribution of linear X-rays transmitted through the object to be inspected;
An X-ray sensor board for simultaneously A / D converting and outputting the detection signal of the linear detector without switching channels;
There is provided a data collection system for an X-ray inspection apparatus, comprising: a sensor timing IF board for transferring data of sensor values of all channels received from the X-ray sensor board to an upper data bus.

  According to a preferred embodiment of the present invention, the X-ray sensor substrate includes an FPGA (Field Programmable Gate Array) or a PLD (Programmable Logic Device) element, which is an element of the linear detector. Each channel has a ΔΣ AD conversion function.

  The ΔΣ AD conversion function of the FPGA or PLD is composed of 1-bit A / D, D / A, a signal delay element, a decimation counter, and a decimation filter for each channel, and each analog signal input from the linear detector Are converted into “coarse” and “fine” pulse signals on the time axis, respectively, and further converted into parallel signals by higher-order digital filter processing.

The linear irradiation device can variably adjust the intensity of X-rays,
The X-ray sensor substrate has a digital gain function that optimizes the level of the detection signal in conjunction with the X-ray energy irradiated to the inspection object.

  It is preferable that the X-ray sensor substrate further has a variation correction function for correcting variations in each detector and measurement system.

  The X-ray is a continuous (CW) X-ray or a high energy pulse X-ray, and when the X-ray is a high energy pulse X-ray, the X-ray sensor substrate is input from a linear detector. Each channel has an integrator that integrates the pulse signal, and the integrator performs charge / discharge operation with the gate signal synchronized with the X-ray irradiation timing to collect data for each X-ray irradiation. preferable.

  According to the configuration of the present invention, since the X-ray sensor board for simultaneously A / D converting and outputting the detection signal of the linear detector without switching the channel is provided, the number of used channels is very large (for example, 2000 to 5000). ) Even in the case, the inspection efficiency is high and the inspection time can be shortened.

  In addition, when the X-ray is a high energy pulse X-ray, an integrator for integrating the pulse signal is provided for each channel, and the charge / discharge operation of the integrator is performed by a gate signal synchronized with the X-ray irradiation timing. Since data is collected for each X-ray irradiation, even high-energy pulse irradiation can be handled in the same manner.

Furthermore, since it has a digital gain function that optimizes the level of the detection signal in conjunction with the X-ray energy irradiated to the inspection object, detection is possible even if the material and thickness of the inspection object are in a wide range.
In addition, by applying this function to locations where different materials overlap, the level of the detection signal is maximized, so that each of the overlapping locations can be detected.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is an overall configuration diagram showing an embodiment of an X-ray inspection apparatus provided with a data collection system of the present invention. In this figure, the X-ray inspection apparatus 10 includes an X-ray generation apparatus 12, an X-ray irradiation apparatus 14, an X-ray detector 16, and a control apparatus 18. In this figure, 1 is an object to be inspected, and 2 is a conveyor for conveying the object to be inspected horizontally.

The X-ray generator 12 generates predetermined X-rays 3. The generated X-ray 3 may be either a continuous X-ray or a pulsed X-ray.
In this example, the X-ray generator 12 includes an X-ray tube 12a and a voltage device 12b. The X-ray tube 12a generates X-rays by accelerating thermoelectrons with an applied voltage and colliding with the anode. The applied voltage is preferably variable in the range of 80 to 300 kV, for example. By switching the applied voltage to, for example, 80, 100,..., 300 kV, the X-ray intensity can be variably adjusted.
In the case of continuous X-rays, the output may be varied at a constant time period T between a predetermined maximum output and minimum output. This output fluctuation can be easily implemented by changing the applied voltage with the voltage device 12b. In this case, the output fluctuation of the X-ray 3 is preferably sinusoidal or rectangular.

The X-ray irradiation device 14 irradiates the inspection object 1 with X-rays 3 generated by the X-ray generation device 12.
In this example, the X-ray irradiation apparatus 14 is a linear irradiation apparatus that linearly irradiates the inspection object 1 with X-rays 3.
With this configuration, the inspection object 1 having a large area is conveyed by horizontally conveying the inspection object 1 on the conveyance conveyor 2 and simultaneously irradiating the X-ray 3 linearly in a direction crossing (for example, orthogonal) in the conveyance direction. Even so, the entire surface can be easily inspected.

The X-ray detector 16 detects the intensity of X-rays that have passed through the inspection object 1.
In this example, the X-ray detector 16 is a multi-channel linear detector that detects the intensity of linear X-rays that have passed through the inspection object 1.
This linear detector includes a plurality of X-ray / light converting elements arranged in a line adjacent to each other, for example, a scintillator, and a plurality of photodiodes that respectively detect light emitted by the X-rays of each scintillator.
With this configuration, the intensity distribution of linear X-rays that have passed through the inspection object 1 can be detected simultaneously by a plurality of scintillators.

  The data acquisition system 20 of the present invention includes a multi-channel linear detector 16 and has a function of simultaneously A / D converting and outputting detection signals of the linear detector without switching channels.

  The control device 18 processes the digital signal received from the data collection system 20 and inspects the inspection object 1.

For example, when the X-ray output generated by the X-ray generator 12 is high and low, the control device 18 detects the X-ray intensity at high output and the X-ray intensity at low output detected by the X-ray detector 16. To classify the material of the object to be inspected 1 by the equivalent atomic number and output the result.
Further, the control device 18 includes a display device 19 for displaying an image of the X-ray intensity transmitted through the object 1 to be displayed on the image by coloring the classification of equivalent atomic numbers.

FIG. 2 is a system block diagram of the entire data collection system.
In this figure, the data collection system 20 of the present invention comprises an X-ray sensor board 22, a sensor timing IF board 24 (hereinafter referred to as IF board), and a frame grabber board 26 built in the control device 18.
The X-ray sensor board 22 is provided with 48 or 64 ch of the X-ray detector 16 per board, detects the intensity of the X-ray transmitted through the inspection object 1 as an analog signal, and then digitally converts it into an IF board 24 as a sensor value. Output to. The IF board 24 transfers the input sensor values of all the channels to the frame grabber board 26 mounted on the host system PC (control device 18).

FIG. 3 is a functional block diagram of the X-ray sensor substrate 22 for low energy continuous X-rays.
The data acquisition system 20 of the present invention employs a ΔΣ AD conversion method, and further uses an FPGA (field programmable gate array) or PLD (programmable logic device) element 23 to multiplex AD conversion of all channels of the detector. Simultaneously without switching.
The ΔΣ AD conversion function is composed of an integrator 27b (Σ) having both a 1-bit A / D 23a (that is, Δ) and a comparator function, and an analog signal input from the X-ray detector 16 is converted into “coarse” and “fine” pulses. Convert to (0 or 1) signal. Also, the quantization error is reduced by sampling at a frequency sufficiently higher than the bandwidth of the input signal.
Except for conventional detectors and peripheral circuits and integrators, ΔΣAD is replaced with a digital circuit. In recent years, high-performance, low-cost FPGAs or PLDs are used, and ΔΣAD for all detector channels is mounted on the logic cells in the FPGA or PLD to increase the measurement line cycle (1/6 = 1 msec in the past) ) Can be realized without increasing costs.

FIG. 4 is a functional block diagram of the X-ray sensor substrate 22 for the high energy pulse X-ray inspection apparatus.
In a low energy X-ray source, X-ray irradiation is continuous on the time axis, but in a high energy X-ray source, irradiation is a pulse operation. Therefore, as shown in this figure, an integrator 25 is newly provided after the X-ray detector 16 of the X-ray sensor substrate 22. The charge / discharge operation of the integrator 25 is performed with the gate signal 25a synchronized with the X-ray irradiation timing, and data is collected for each X-ray irradiation (integration and ΔΣ AD conversion for each pulse output from the X-ray detector). To do.

  FIG. 5 is a configuration diagram of the X-ray sensor substrate 22 actually manufactured. In this example, the X-ray sensor substrate 22 is composed of one master substrate 22A and at least one slave substrate 22B. The number of connected slave boards can be arbitrarily changed.

  In this figure, 16 is a 48ch X-ray detector, 27a is a 48ch current-voltage conversion circuit, 27b is an integrator having a 48ch comparator function, and 23 is an FPGA (field programmable programmable controller) having a 48ch ΔΣ AD conversion function. Gate array) element, 27c is CONFIG ROM, 27d is crystal oscillator (16MHz), 27e is REF power supply, 27f is SR power supply of 12V → 3.3V, 27g is SR power supply of 12V → 2.5V, 27h is 24V → A 1.5V SW power source, 27i is a LAN connector, 27j is a power connector, and 28 is a daisy chain connector.

The master board 22A and the slave board 22B have the same board design, and are distinguished by mounting / not mounting some components. Further, the master board 22A and the slave board 22B transmit and receive data to and from each other through the daisy chain connector 28.
Only the master substrate 22A has a crystal oscillator (16 MHz) 27d, and is transferred to the slave substrate 22B as an FPGA clock and a data synchronization clock.
The CONFIG ROM 27c has only the master substrate 22A, and passes the contents to the slave side.
Only the master board 22A has a power connector 27j and a data connector 27i with the I / F board 24.
With this configuration, the detection signals of the X-ray detectors 16 on the maximum 48 ch × 240 sensor substrates can be simultaneously A / D converted and output without switching channels.

  FIG. 6 is a circuit configuration diagram of the X-ray sensor substrate 22 for low energy continuous X-rays. As shown in this figure, the X-ray sensor board 22 includes a 48ch X-ray detector 16, a 48ch current / voltage conversion circuit 27a, an integration amplifier 27b having a 48ch comparator function, an FPGA element 23, and a data bus 29. . The data bus 29 is connected to the FPGA 23 and the frame grabber substrate 26 through 16-pit communication lines 30a and 30b.

The FPGA element 23 has a ΔΣ AD conversion function for each channel of the linear detector (48-channel X-ray detector 16). As shown in FIG. 7, this ΔΣ AD conversion function is constituted by each channel, a dimming counter 23b, a dimming filter 23c, and a delay element (Z ⁻¹ ) 23d, and each analog input from the linear detector. Each signal is converted into a pulse signal bit stream of “coarse” and “fine” on the time axis.

  The X-ray sensor substrate 23 has a digital gain function that optimizes the level of the detection signal in conjunction with the X-ray energy irradiated to the inspection object, and a variation correction function that corrects variations in each detector and measurement system.

  FIG. 8 is a configuration diagram of an X-ray sensor substrate 22 for a high energy pulse X-ray inspection apparatus. In this example, the X-ray sensor board 22 includes a 64ch X-ray detector 16, a 64ch current / voltage conversion circuit 27a, an integration amplifier 27b having a 64ch comparator function, an FPGA element 23, and a data bus 29. The data bus 29 is connected to the FPGA and the frame grabber substrate 26 via 16-pit communication lines 30a and 30b.

In this example, the X-ray sensor substrate 22 includes an integrator 25 for integrating the pulse signal input from the linear detector 16 for each channel, and generates a gate signal 25a synchronized with the X-ray irradiation timing. Thus, the charge / discharge operation of the integrator 25 is performed, and data is collected for each X-ray irradiation.
In this figure, 23f is a memory, and 21 is a charge / discharge signal transmitter, which outputs a charge / discharge signal by an external trigger signal.

  According to the configuration of the present invention described above, since the X-ray sensor substrate 23 for simultaneously A / D converting and outputting the detection signal of the linear detector 16 without switching the channel is provided, the number of channels used is very large (for example, 2000-5000), the inspection efficiency is high and the inspection time can be shortened.

  Further, when the X-ray is a high energy pulse X-ray, an integrator 25 for integrating the pulse signal is provided for each channel, and the integrator 25 is charged / charged by a gate signal 25a synchronized with the X-ray irradiation timing. Since the discharge operation is performed and data is collected for each X-ray irradiation, even high-energy pulse irradiation can be handled in the same manner.

Furthermore, since it has a digital gain function that optimizes the level of the detection signal in conjunction with the X-ray energy irradiated to the inspection object, detection is possible even if the material and thickness of the inspection object are in a wide range.
In addition, by applying this function to locations where different materials overlap, the level of the detection signal is maximized, so that each of the overlapping locations can be detected.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.

1 is an overall configuration diagram showing an embodiment of an X-ray inspection apparatus provided with a data collection system of the present invention. It is a system block diagram of the data acquisition system for low energy continuous X-rays. It is a functional block diagram of an X-ray sensor board. It is a functional block diagram of the X-ray sensor board | substrate for high energy pulse X-ray inspection apparatuses. It is a block diagram of the X-ray sensor board | substrate actually manufactured. It is a circuit block diagram of the X-ray sensor board | substrate for low energy continuous X-rays. It is a functional block diagram of a ΔΣ AD conversion function. It is a block diagram of the X-ray sensor board | substrate for high energy pulse X-ray inspection apparatuses.

Explanation of symbols

1 Inspected object, 2 Conveyor, 3 X-ray,
10 X-ray inspection equipment, 12 X-ray generation equipment,
12a X-ray tube, 12b voltage device,
14 X-ray irradiation device, 16 X-ray detector,
18 control device, 19 display device 20 data collection system, 21 charge / discharge signal transmitter,
22 X-ray sensor board, 22A Master board, 22B Slave board,
23 FPGA element or PLD element 23a 1 bit A / D (Δ),
23b Digimation counter, 23c Digimation filter,
23d Delay element (Z ⁻¹ ), 23e 1-bit D / A,
23f memory,
24 sensor timing IF board,
25 integrator, 25a gate signal, 26 frame grabber substrate,
27a current voltage conversion circuit, 27b integrator having a comparator function,
27c CONFIG ROM, 27d crystal oscillator,
27e REF power supply, 27f SR power supply, 27g SR power supply,
27h SW power supply, 27i LAN connector, 27j power supply connector,
28 daisy chain connectors, 29 data buses,
30a, 30b communication line

Claims (7)

A data collection system for an X-ray inspection apparatus that inspects an inspection object from the intensity of X-rays transmitted by irradiating the inspection object with X-rays,
A linear irradiation apparatus that linearly irradiates a target object with predetermined X-rays;
A multi-channel linear detector for detecting the intensity distribution of linear X-rays transmitted through the object to be inspected;
An X-ray sensor board for simultaneously A / D converting and outputting the detection signal of the linear detector without switching channels;
A data collection system for an X-ray inspection apparatus, comprising: a sensor timing IF board for transferring the sensor values of all channels received from the X-ray sensor board to an upper data bus.   The X-ray sensor substrate has an FPGA (Field Programmable Gate Array) or PLD (Programmable Logic Device) element, and the element has a ΔΣ AD conversion function for each channel of the linear detector. The data collection system of the X-ray inspection apparatus according to claim 1.   The ΔΣ AD conversion function of the FPGA or PLD is composed of 1-bit A / D, D / A, a signal delay element, a decimation counter, and a decimation filter for each channel, and each analog signal input from the linear detector The X-ray inspection apparatus according to claim 2, wherein each of the signals is converted into a "rough" and "fine" pulse signal bit stream on a time axis, and further converted into parallel signals by high-order digital filter processing. Data collection system. The linear irradiation device can variably adjust the intensity of X-rays,
The data of the X-ray inspection apparatus according to claim 1, wherein the X-ray sensor substrate has a digital gain function that optimizes the level of a detection signal in conjunction with the X-ray energy irradiated to the inspection target. Collection system.   The data collection system for an X-ray inspection apparatus according to claim 1, wherein the X-ray sensor substrate further has a variation correction function for correcting variations in each detector and measurement system.   The X-ray is a continuous (CW) X-ray or a high energy pulse X-ray. When the previous X-rays are high energy pulse X-rays, the X-ray sensor substrate includes an integrator for each channel that integrates the pulse signal input from the linear detector, and synchronizes with the X-ray irradiation timing. 2. The data collection system for an X-ray inspection apparatus according to claim 1, wherein the integrator performs charge / discharge operation with the gate signal and performs data collection for each X-ray irradiation.

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