JPH01157040A - Microfocus x-ray device - Google Patents

Abstract

PURPOSE:To unify density distribution and reduce the effect of a density difference even if there should occur more or less dislocation of a focal point by making a target chip of a material having an absorption coefficient equal to or less than the coefficient pertaining to copper, and forming the top of the target chip into a recess type inverted conical shape. CONSTITUTION:A target 6 comprises a target chip 1 and a target body 2 and via the combination thereof, a hollow part 3 is formed within the target body 2. This target body 2 is fitted with an air vent hole 5 for the hollow part 3. Also, the target chip 1 is inverted conical type suitable for a distance between a focal point and a film 11 and furthermore so shaped as to be capable of constituting a hollow part when combined with the target body 2. Consequently, it becomes possible to obtain an X-ray of uniform intensity at all times. Also, a material having an absorption coefficient equal to or less than the coefficient of copper is used for construction. According to the aforesaid construction, an X-ray can be generated around 360 degrees in forward and aft directions.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an X-ray device, and particularly to the structure of a microfocus X-ray device that emits 360-degree Xfs radiation.

<Prior art> The targets for the front and rear beams of the conventional microfocus X-ray apparatus are aluminum flat targets or steel conical targets as shown in FIGS. 11 and 12. It is used as shown in the figure.

However, in the front and back, as well as in the circumferential direction,
No special consideration was given to the fact that differences in the intensity of lines and differences in density on the photographed film would cause temperature fluctuations. FIG. 4 shows the relationship between the intensity of X-rays and the density on the film.

<Problem to be solved by the invention In the conventional aluminum flat target, the target material is solid (solid material: a member made of a single material), so the forward beam (electron beam is directed vertically downward from above) (See Figure 10B)
The line became extremely weak and it was not possible to take pictures using the forward beam. In addition, with a steel conical target, it is possible to image with the front and rear beams, but because the distance between the focal point and the film changes, a large concentration difference occurs in the axial direction.Furthermore, due to the influence of the subject and the surrounding magnetic field, the miko beam There is a problem in that when the light beam is deflected and defocused, a difference in density occurs in the circumferential direction and in the axial direction due to the difference in the transmission thickness.

<Objective of the Invention> The object of the present invention is to reduce the density difference of the above-mentioned problem, to provide a target with a uniform density distribution, and to reduce the influence of this density difference even if some defocus occurs. The purpose of this invention is to develop a target and provide a microfocus X-ray device equipped with this target.

Summary of Means for Producing the Means> In short, the present invention provides a microfocus X-ray device that has a target chip that generates X-rays by collision of electron beams, and a target body to which the target chip is attached. It is a microfocus X-ray device that is made of a material that has a coefficient, has a concave inverted conical top, and has a hollow part with a conical inner surface symmetrically provided on the target body side.

<Example 1> Before entering into the description of the example, a microfocus X-ray apparatus will be described. Figure 9 is a side view showing the concept of the device.
Electrons sent out from the filament 104 of 03 are accelerated toward the anode 105. These electrons pass through the anode window and are focused by the deflection mechanism 115 to the target 1.
It corresponds to 06. As a result, 660° direction (panoramic direction)
X-rays are generated.

As shown in FIG. 10B, the upper part of the plane perpendicular to the XaC beam and including the source focus 111 is called the rear beam, and the lower part is called the front beam.

FIG. 10A is a schematic front view when inspecting and photographing a welded portion between a tube and a tube plate (for example, of a heat exchanger) in a 560° direction at once.

FIG. 4 is a diagram showing the relationship between X-ray intensity and film density; the greater the X-ray intensity, the higher the film density.

However, if the film density is too high, there is a problem that photographic observation cannot be performed.

Figure 5 shows the relationship between the object to be inspected (e.g. tube wall) and the distance from the radiation source, and shows schematically that the thicker the tube wall, the weaker the intensity of the X-rays after passing through it. This is shown in contrast with the reference numeral A in FIG. The symbol B indicates that the intensity of Xa decreases in inverse proportion to the square of the distance from the radiation source.

FIG. 11 shows the change in X-ray intensity for a film when using a flat-topped target tip, and shows an example of a rear beam. FIG. 12 shows the X-ray intensity distribution for a lipstick-shaped target.

The foregoing requires the use of a target such that the X-rays projected onto the film 116 are of approximately the same intensity, resulting in an image film in which the detection areas are shown with different densities.

FIGS. 1 and 2 show an embodiment of the present invention. FIG. 1 is a front view of an inverted conical hollow target according to the present invention, and FIG. 2 is a side view thereof.

As shown in Figure 2, this target consists of a target chip that is hit by an electron beam, and a target body that fixes it to a microfocus X-ray device.By combining these with a screw-in structure, the target body It can be configured as a target having a hollow part 3 which is a space inside.

The target body has an air vent hole 5 in the hollow part 3, and the target chip is an inverted conical type (concave tip) depending on the distance between the focal point and the film, and when combined with the target body, the hollow part is formed. It has a door shape that allows you to use it. A material with an absorption coefficient below that of the copper ingot is used as the material.

The effect of an inverted conical hollow target tip will be considered in Fig. 3.

The intensity of X-rays is as follows.

(1) - The rate of generation of X-rays inside the shell is strongest in the OB direction, and gradually becomes weaker toward the OA side.

(2) Since the intensity of X-rays is inversely proportional to the square of the distance between the source and the film, it is strongest at the OB and becomes weaker as it moves toward the OA side in inverse proportion to the square of the distance.

(3) By changing the thickness through which the X-rays pass through the target (α, b, c in the figure above), the intensity of the X-rays can be changed (1).
) and (2), the balance is achieved and finally X
There is no large difference in the intensity distribution of the lines.

(4) Even if the focal point position is slightly shifted (one dimension in the upper right figure) (Fig. 15), the difference in X-ray intensity is small due to the shape effect.

There are various advantages such as:

<Example 2> This is an improvement that has been made.

<Embodiment 3> FIG. 7 shows a mask-type target and aims to achieve the same effect as in FIG. 6. All of these are achieved by changing the thickness of X-ray transmission depending on the distance between the focal point and the subject, and by widening the range that the electron beam hits.

〈Example 4〉 Figure 8A shows a plate-type target, which enables 360° (spherical) X-ray irradiation by making the target a plate, so that the range hit by the electron beam is wide. This reduces the effects of defocus. 8th B,
The figure is a perspective view, and a plurality of pillars, such as 1 to 4 pillars, can be used for the disc 9.

Effect> The target of the present invention collides with an electron beam, and by using a material with an X-ray absorption coefficient as low as that of a copper ingot, X-rays are generated in a 360' direction in front and behind the target. The shape of the chip is inverted conical (concave) in which the thickness of the Xi transmitted through the film is changed depending on the distance between the focal point and the film, and by making it hollow, it has the function of obtaining X-rays of uniform intensity. (See Figures 3 and 14). Further, the air vent hole 5 in the target body is provided in the hollow portion 3 in order to prevent the target from being heated and deformed by X-ray irradiation.

<Effects of the Invention> By implementing the present invention, the front and rear beams can uniformly cover a wide range of film in the axial direction in one shooting by using the shape of the tip of the target and the hollow shape according to the distance between the focal point and the film. The density distribution can be obtained, and even if the electron beam does not hit the center of the target and is out of focus (see Figure 15), a photograph with no density difference in the circumferential direction can be obtained, so the image of the X-ray photograph can be Quality will be improved.

FIG. 14 shows this effect as an X-ray intensity distribution, and when compared with FIG. 16, which shows the intensity distribution of a conventional target, it is easy to see that this effect exists.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a target according to the first embodiment of the present invention, Fig. 2 is a front view, Fig. 3 is an explanatory diagram of the effect of the inverted conical type of the target tip, and Fig. 4 is the intensity of X-rays. Figure 5 is a diagram showing the relationship between the thickness of the object to be inspected and the distance from the X-ray source, and the X-ray intensity is indicated by the size of the arrow. 7 is a partial sectional view of the target of the third embodiment, FIG. 8A is a partial sectional view of the target of the third embodiment, and FIG. 8B is a partial sectional view of the target of the third embodiment. Perspective view, No. 9
The figure is a schematic vertical cross-sectional view of a microfocus X-ray device, Figure 10A is a partial cross-sectional view showing the situation in which it is used to take an X-ray photograph of a weld between a tube and a tube plate, and Figure 10B is a front beam and a rear beam. Fig. 11 is an explanatory drawing of the rear beam and X-ray intensity in the conventional device, Fig. 12 is a drawing showing an example of the front and rear beams in the conventional device, and Fig. 13 is the conventional FIG. 14 is an X-ray intensity distribution diagram for the first embodiment of the present invention, and FIG. 15 (A) shows the influence of beam deviation of the conventional target and (B ) is a drawing for comparison with the figure. 1- Target chip 2 Target body 6 Hollow part 4 Threaded part 5 Air vent hole 7 Target chip 8 of the sixth embodiment... Fourth embodiment Target chip 9...Circle plate 10
・・・Support 11...Film Figure 4] ↓Mu I 0 Figure 5 Figure 1 Figure 3 II/4 Lum entry Heisei @ # 1 February 6

Claims (1)

[Claims] 1. In a microfocus X-ray device having a target chip that generates X-rays by collision with an electron beam and a target body to which the target body is attached, the material of the target chip is a material having an absorption coefficient of copper or less. , and a microfocus X-ray apparatus characterized in that the top of the target is a concave inverted conical shape, and a hollow part having a conical inner surface is provided on the target body side in symmetry with this. 2. The microfocus X-ray apparatus according to claim 1, wherein the recess at the top of the target is formed into a dish shape. 3. The microfocus X-ray device according to claim 1, characterized by a structure in which the target disk is held by one or more arms extending from the target body.