JPH0413680B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a full-circle irradiation type X-ray device used when, for example, inspecting a welded part of a steel pipe by taking an X-ray transmission image. Regarding.

[Technical background of the invention and its problems] The all-round irradiation type X-ray device according to the prior art is
It is configured as shown in the figure. The accelerated electron beam e passes through the interior of the X-ray tube 1, which is maintained in a near-vacuum state, and collides with the tip 2t of the target 2. At the time of collision, X-rays from the tip 2t of the target 2 are directed toward the target 2 in the entire circumferential direction X _A ,
Irradiated by X _B. The X-rays irradiated at this time are
After passing through the target holder 3 and the object to be inspected 4, the light reaches the X-ray film 5 and exposes the film.

When the electron beam e collides with the precise position of the tip of the target 2, X-rays are generated uniformly in the circumferential direction. However, if the electron beam does not exactly collide with the tip 2t of the target 2 as shown in e' due to deformation of the X-ray tube due to external mechanical factors or changes in the course of the electron beam e due to electromagnetic factors, etc. This means that no X-rays will be generated. To prevent such a phenomenon, a normal all-round irradiation type X-ray device has a slit 6 for restricting the passage of the electron beam, and a slit 6 for restricting the passage of the electron beam, and a
It is equipped with an amplifier 8 and an ammeter 9 for reading a minute target current generated on a target 2 which is electrically insulated from the X-ray tube 1 by an insulator 7. Furthermore, when the relative positional relationship between the electron beam e and the target 2 changes due to the external factors mentioned above, and the electron beam e becomes in a state like e' with respect to the target 2, the electron beam It has a deflection coil 10 for correcting the course.

Figures 2 and 3 show the electron beam e according to the prior art.
In the principle diagram of the deflection mechanism, the electron beam e is connected to the deflection coil 1.
After the position in the X and Y directions is determined by 0, the electron beam e is focused by the focusing coil 11, collides accurately with the tip of the target 2, and is most efficiently converted into X-rays. It is adjusted as follows. In order to correct the course of the electron beam e in the X and Y directions, the deflection coil 11 includes four coils 10a and 1 in the circumferential direction of the X-ray tube 1, as shown in FIG.
It has 0b, 10c, and 10d. Power is supplied to these four coils 10a _to 10d so that magnetic fields _φ There is.

Using such a deflection mechanism for the electron beam e, the second
The electron beam e in the figure passes through the slit 6 and is adjusted so as to reach the target 2 to generate X-rays. Furthermore, the electron beam e passes through the center of the slit 6 accurately, and the target 2 is
If the electron beam e does not collide accurately with the tip 2t of the target 2, for example, when using the target 2 whose tip 2t has a conical shape, the irradiated X-rays X _A , X _B
The strength is not uniform in the circumferential direction, and X _A ≠ X _B. Therefore, the voltage (or current) must be finely adjusted.

FIG. 4 schematically shows the procedure for adjusting the electron e to pass through the center tip 2t of the slit 6 when a conventional electron beam deflection mechanism is used. The slit 6 is shown in cross section perpendicular to the path of the electron beam e. Now, if the magnetic fields φ _x and φ _y of the deflection coil 10 are not adjusted,
Assuming that the electron beam e is passing through the position P, the target current cannot be detected because the electron beam e has not reached the target.

Therefore, as the first step of adjustment, the magnetic fields φ _x and φ _y of the deflection coil 10 are adjusted so that the path of the electron beam e passes through the inside of the slit 6, and the target current is detected. Make it.

As a second step, after the target current is detected, the position of the path of the electron beam e in the x-axis direction is adjusted. If the position of the electron beam e at the time when the target current is detected is Q, the course of the electron beam e can be changed by adjusting the voltage (current) applied to the deflection coil 10 arranged in the x-axis direction. ,A→Q→
The target current It changes as shown in FIG. 4 as O'→B. Therefore, the deflection coil 1 is in a state where the current value is 1/2It compared to the current value It when the target current is maximum.
Read the voltage (current) values V _A (I _A ) and V _B (I _B ) at 0, Vo' = (V _A + V _B )/2, (Io' = (I _A +
The voltage (current) of the deflection coil 10 is determined by the value of I _B )/2).
By adjusting , the path of the electron beam will pass through the position O'.

As a third step, the voltage (current) of the deflection coil 10 arranged in the y-axis direction is determined by the same operation as V _p =
By adjusting (V _P +V _E )/2 and (Io = (I _D +I _E )/2), the path of the electron beam e becomes position O, and the electron beam e passes through the center of the slit 6. It is possible to adjust it as follows.

As described above, in the electron beam e deflection mechanism according to the conventional technology, the method for adjusting the path of the electron beam e is complicated;
Moreover, it requires a large amount of time for investigation. In particular, the diameter of the slit 6 in the portion through which the electron beam e passes is about φ ₁ , and when the path of the electron beam is far from the slit hole, the electron beam e passes through the slit hole 6 of φ ₁ . It is very difficult to adjust the magnetic fields φ _x , φ _y of the deflection coil 10 in the x and y directions so that As the time required for adjustment becomes longer, work efficiency decreases and the X-ray generation time becomes longer, which is also unfavorable in terms of radiation work management.

[Object of the Invention] An object of the present invention is to provide an all-round irradiation type X-ray device that can adjust the path of an electron beam in a short time so that it passes accurately through the center of a slit.

[Summary of the Invention] The all-round irradiation type X-ray device according to the present invention further superimposes a continuous wave voltage (current) such as a sawtooth wave, a sine wave, and a triangular wave on the DC voltage (current) applied to the deflection coil. By scanning the electron beam in the X and Y directions and modulating the brightness with the target current obtained for the waveform superimposed on the CRT, the slit position can be easily confirmed visually. The device is characterized in that it is configured to adjust the path of the electron beam.

[Embodiments of the Invention] The present invention will be described below with reference to an embodiment shown in FIG. In Figure 5, Figures 1, 2 and 3
The same reference numerals as those in the drawings indicate the same parts, so the explanation thereof will be omitted. In the present invention, an adder 1 is provided in the excitation circuit of the deflection coil 10 provided in the X-ray tube 1.
2 is provided, and this adder 12 has a sawtooth waveform, as shown in the figure.
Continuous wave voltages (currents) such as triangular waves and sine waves V _x (t) and V _y (t) (or I _x (t) and I _y (t)) are converted into DC voltages (currents) V _x and V _y ( In addition, the continuous wave voltages (currents) V _x ( _t ) and V _y ( _t ) on an oscilloscope, etc.
It is configured to be input to the X and Y terminals of the CRT display 13. The target current is amplified by amplifier 8 and
-Y Brightness modulates the input signals input to the X and Y terminals of the CRT display 13.

6a and b show continuous waves V _x (t) and V _y (t) (or I _x (t)) applied to the deflection coil 10.
_FIG . 6a shows the deflection coil 1 which controls the electron beam e in the x-axis direction.
This is the waveform applied to 0b and 10d, and its potential is
Changes in the order of Bn → Ao → Bn. Further, the amount of voltage change in the waveform in FIG. 6b for each cycle of the waveform in FIG. 6a is ΔV _y .

FIG. 7a shows that the current and voltage V _x and V _y applied to the deflection coil 10 are the continuous waves V _x shown in FIGS.
The irradiation position of the electron beam e is shown with respect to the slit 6 when (t) and V _y (t) are superimposed. Figure 7b is the continuous wave shown in Figures 6a and b.
When V _x (t) and V _y (t) are applied to the X-axis and Y-axis of the X-Y CRT display 13
A display example of the Y CRT display 13 is shown.

In the display example of the X-Y CRT display 13 shown in FIG. 7b, the bright spots change from Ao→Bo→Al→Bl... Changes like →An→Bn. At this time, the X and Y positions of the bright spots on the screen are determined only by the values of V _x (t ₁ ) and V _y (t ₁ ) with respect to time t ₁ . The scanning range of the bright spot on the screen is determined by the maximum potential value maxV _x (t) and
maxV _y (t), but by setting maxV _x (t) and maxV _y (t) appropriately in advance, the scanning range and position of the bright spot can be made constant.

On the other hand, as shown in FIG. 7a, the actual scanning position of the electron beam is determined by the voltage V _x +V _x applied to the deflection coil 10.
(t) and V _y +V _y (t),
Since V _x and V _y (t) have waveforms centered on 0 volts, the center of the scanning range of the electron beam e is V _x ,
V is equal to the position determined by _y . Therefore
The values of V _x and V _y are the appropriate voltage values V _x ′ and V _y ′ necessary for passing the electron beam e through the center of the slit 6.
If this is different, the scanning position of the electron beam e will be shifted with respect to the slit 6. At this time, a part of the scanned electron beam passes through the slit 6,
Since it reaches the tip 2t of the target 2, it is detected by the target current, and the brightness of the bright spot on the X-Y CRT display 13 is modulated to change the brightness of the bright spot. Therefore, the shape of the slit 6 is displayed on the X-Y CRT display 13 as a collection of brightness-modulated dots.

This luminance-modulated slit image 15 in FIG. 7b
Since the brightness is modulated by the path of the electron beam e, changing the value of V _x or V _y changes the path of the electron beam e, and as a result, X-Y
The slit image 15 on the CRT display 13 is
It moves in the X-axis and Y-axis directions in accordance with the amount of change in V _x or V _y . Voltage required for electron beam e to pass through the center of slit 6 by changing V _x and V _y
When V _x ' and V _y ' are respectively equal to
The display on the display 13 is displayed as shown in FIG. 8b.

That is, the slit image 15 is moved on the X-Y CRT display 13, and the scanning range of the bright spot is
V _x (t) to the deflection coil 10 by superimposing it on the center of Ao→Bo→Al→…B _o-1 →An→Bn
When the application of V _y (t) is stopped, the path of the electron beam e will exactly pass through the center of the slit 6 (the position of the electron beam e determined only by V _x and V _y is , is always the center on the X-Y CRT display 13.) However, at that time, V _x (t)
It is necessary to set in advance so that the center of the amplitude of V _y (t) and V y (t) is located at the center of the XY CRT display 13. Also V _x (t) and V _y (t)
By changing the amplitudes maxV _x (t) and maxV _y (t) of The size can be changed. As a result, the slit image 15
It is possible to use the slit image 15 in a small size for quick detection and a large slit image 15 for accurate position adjustment.

After the scanning center of the electron beam e is adjusted to the same position as the center of the slit 6 in this way, V _x (t) and V _y (t) applied to the deflection coil 10 are set to 0.
By doing so, the electron beam e always passes through the center of the slit 6, making it possible to generate stable X-rays.

[Effects of the Invention] As described above, in the present invention, a direct current and an electron beam are supplied to the deflection coil for determining the position of the electron beam.
The slit hole position can be determined by superimposing and applying a continuous wave for making small changes in the Y direction and displaying the continuous wave whose brightness is modulated by the obtained target current on a CRT display.
It can be displayed on a CRT display.
As a result, the position of the slit hole relative to the position of the electron beam can be visually confirmed at all times, so that the course of the electron beam can be adjusted to the center of the slit hole accurately and in a short time.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the target part of the all-round irradiation type X-ray device, Fig. 2 is an overall block diagram of the all-round irradiation type X-ray device including the deflection film part, and Fig. 3 is the line shown in Fig. 2. FIG. 4 is an explanatory diagram showing the procedure for adjusting the position of the electron beam; FIG. Figures a and b are continuous waveform diagrams applied to the x-axis direction coil and Y-axis direction coil of the deflection coil, Figures 7a and b are waveform diagrams showing the scanning position of the electron beam and display examples, and Figure 8a and b are waveform diagrams showing the scanning position of the electron beam after position adjustment of the electron beam and a display example of the display. 1...X-ray tube, 2...Target, 2t...Target tip, 3...Target holder, 4...
Object to be inspected, 5... X-ray film, 6... Slit, 8... Amplifier, 10... Deflection coil, 11...
...Focusing coil, 12...Adder, 13...CRT
Display, 14...Modulator, 15...Slit image, V _x , V _y ... DC voltage, V _x (t), V _y (t)
...Continuous waves.

Claims (1)

[Claims] 1. An X-ray system in which an accelerated electron beam is deflected by a deflection coil through an X-ray tube, passes through a slit in the tube, and collides with the tip of a target, and upon collision, X-rays are emitted all around the tube. The device includes an adder that superimposes a continuous waveform in which the voltage or current changes over time on a DC voltage or current and supplies it to the deflection coil, and a target current that is generated when the electron beam collides with the target. a modulator for modulating the brightness of the continuous waveform of the voltage or current according to the target current, and a CRT display for displaying the continuous waveform in response to the output of the modulator. ,the
A full-circle irradiation type X-ray device characterized by being configured to display the positional relationship of a slit with respect to the path of an electron beam on a CRT display screen.