JPH03273105A - Automatic x-ray inspection device - Google Patents

Abstract

PURPOSE:To cope with short-period variation in X-ray intensity due to source voltage and load variation and long-period variation due to the aging of an X-rays tube by performing feedback control over the intensity of X-rays and suppressing the variation in X-ray intensity. CONSTITUTION:The high frequency voltage outputted by a high frequency generating circuit 1 is converted by a multistage voltage doubling circuit 2 into a high DC voltage, which is applied to the X-ray tube 3 to generate X rays. The X rays irradiate a body 7 to be inspected which is carried in an X-ray irradiation part by a belt 5 for conveyance. Then an X-ray transmission image of the body 7 to be inspected is converted by an image pickup tube 6 into an electric video signal, which is processed by an image processing part 8 to decide whether the body 7 is normal or defective. A defective is removed by a rejecting mechanism 9. Further, if the output voltage varies owing to load variation or a ripple nd the X rays vary in intensity, the frequency of the output voltage of the circuit 1 is varied to control the X-ray intensity to a constant value. The brightness of the X-ray image can accurately be compared with set gradations without being affected by the variation in X-ray intensity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic X-ray inspection device, and more particularly to an automatic X-ray inspection device that performs image processing to automatically determine the internal structure of a subject.

[Conventional technology and its issues]

This type of conventional device uses a method in which a commercial frequency voltage is boosted as an X-ray generation source, subjected to half-wave or full-wave rectification, and then stored in a capacitor to be smoothed and applied to the XuA tube. However, this method has the disadvantage that detection by image processing is not stable because the intensity of the X-rays emitted from the X-ray tube fluctuates due to fluctuations in the power supply voltage or pulsations due to the load, and the brightness of the X-ray transmission image is not constant. be. For this reason, a method has been used to suppress fluctuations in the output by increasing the size of the capacitor, but this method has the disadvantage of increasing the size of the device and increasing the cost. Furthermore, in addition to the fluctuations in the applied voltage, fluctuations in the X-ray intensity also include changes over time due to deterioration of the X-ray tube, and no particular measures have been taken to deal with this problem.

An object of the present invention is to provide an automatic X-ray inspection device that can cope with both short-term fluctuations in X-ray intensity due to changes in power supply voltage and load, and long-term fluctuations due to deterioration of an X-ray tube over time.

[Means to solve the problem]

In order to achieve the above objects, the present invention provides an automatic X-ray inspection device that irradiates an object with X-rays emitted from an In this, the high voltage supply section of the X-ray generation source consists of a high frequency generation circuit and a multistage voltage doubler circuit that converts the AC input voltage from the high frequency generation circuit into a DC high voltage, and supplies the DC high voltage to the X-ray tube. A sensor for monitoring the applied and output X-ray intensity is provided, and means is provided for varying the frequency of the output voltage of the high frequency generation circuit based on the output of the sensor.

[For production]

When the output voltage fluctuates due to load fluctuations or ripples and the X-ray intensity changes, the frequency of the output voltage of the high-frequency generating circuit is varied according to the amount of change, and the X-ray intensity is controlled to be constant. Therefore, the brightness of the X-ray image is not affected by fluctuations in X-ray intensity, and the brightness of the X-ray image is
Accurate comparison with lIm can be made.

〔Example〕

The present invention will be explained in detail below.

Figure 1 shows the X! ! This device is composed of an X-ray generation source, an X-ray detection section, an image processing section, and a subject transport system.

The X-ray generation source consists of a high frequency generation circuit 1 and a multistage voltage doubler circuit 2 (
For example, a Kotscroft circuit) and an X-ray tube 3, the high-frequency voltage output from the high-frequency generating circuit 1 is converted into a DC high voltage by a multistage voltage doubler 2 and applied to the Xi tube 3 to generate X-rays. These X-rays are irradiated onto the subject 7 that is carried into the X-ray irradiation section by the conveyor belt 5. The X-ray transmitted image of the subject 7 is converted into an electrical video signal by the image pickup tube 6 and subjected to image processing by the single image processing section 8 to determine whether the subject is good or bad. Then, the defective products are removed by the removal mechanism 9.

By the way, in order to stabilize the xi intensity, it is necessary that the voltage applied to the X-ray tube be stable.

That is, as shown in FIG. 3, the output voltage of the multistage voltage doubler circuit is the value obtained by subtracting the voltage drop ΔV due to the load and the ripple δV from the output voltage V at no-load. Here, the second
As the conditions for the circuit shown in the figure, C1=C2=... ・=C
2n=C If the frequency of the input voltage is f1 and the load current is I, then

Therefore, by increasing the capacitance C of the capacitor or increasing the frequency f of the input voltage, △V, δ■
can be made smaller. However, increasing the size of the capacitor increases the size and cost of the device, so the present invention uses a high frequency generation circuit to increase the frequency f and stabilize the output voltage.

Also, when performing image processing on X-ray images, as shown in Figure 4,
The brightness of the image is decomposed into 256,141 tones, and the detected object is extracted by comparing the set value of the gradation corresponding to the detected object with the image. Therefore, XM, image brightness (gradation)
If it fluctuates due to △V and δV, comparison with the set value cannot be performed accurately, resulting in false detection. In other words, △V is the average brightness fluctuation, and δ■ is the instantaneous brightness fluctuation. appear.

Therefore, when processing images, x! ! As a means of keeping the X-ray intensity constant when obtaining a transmission image, a sensor for monitoring the X-ray intensity is provided in the X&I irradiation section, and the frequency f of the output voltage of the high-frequency generating circuit l is controlled based on the sensor output. , △
In order to obtain a constant X-ray intensity by varying V and δ■
It's all in order.

For example, when operating at f=15KH2, if the X-ray intensity decreases due to power supply voltage fluctuations, X-ray tube deterioration, temperature changes, etc., increase f to, for example, 18KHz until the initially set X-ray intensity is reached. and adjust.

According to this embodiment, the rate of variation in X-ray intensity is kept at 1% or less, making it possible to perform extremely stable inspections.

In addition, since frequency control only changes the switching period of the high frequency generation circuit, the n-times configuration becomes simple. Note that, instead of adjusting the frequency f, the same effect can be obtained by changing the pulse or peak value of the output voltage of the high frequency generation circuit.

〔Effect of the invention〕

As described above, according to the present invention, by controlling the X-ray intensity in a food pack, fluctuations in the X-ray intensity are suppressed and its stability is ensured, thereby increasing the stability of automatic detection.

Furthermore, since there is no need to increase the capacitance of the capacitor to suppress fluctuations in X-ray intensity, the apparatus can be made more compact.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing an embodiment of the automatic X-ray inspection device of the present invention, Fig. 2 is a multi-stage voltage doubler circuit diagram, Fig. 3 is an output voltage waveform diagram of the multi-stage voltage doubler circuit, and Fig. 4 FIG. 2 is a diagram illustrating image processing of an X-ray image. 1...High frequency generation circuit, 2...Multi-stage voltage doubler circuit,
3... X-ray tube 5 4... X-ray intensity sensor, 5...
・・Transportation belt, 6.・X-ray transmission imaging tube, 7.・
- Subject 8... Image processing device. Figure 1 Figure 1 1.#lHyakusai Hatsuja Iku Aka 8' A (Satoshi ni Merz [1? 91st place R mark

Claims (1)

[Claims] (1) In an automatic X-ray inspection device that irradiates a subject with X-rays emitted from an X-ray source and processes the X-ray transmission image of the subject to determine the quality of the internal structure, The high voltage supply section consists of a high frequency generation circuit and a multistage voltage doubler circuit that converts the AC input voltage from the high frequency generation circuit into a DC high voltage, and applies the DC high voltage to the X-ray tube to output X. An automatic X-ray inspection device includes a sensor for monitoring ray intensity and means for varying the frequency of the output voltage of a high frequency generation circuit based on the output of the sensor.