JPS62226547A - X-ray image intensifier tube - Google Patents

Abstract

PURPOSE:To prevent halation and sticking due to excessive X-rays, by installing a liquid crystal shutter at the light incident side of a photoelectric device. CONSTITUTION:A liquid crystal shutter 52 is set up between an LG-Cs1 input phosphor layer 26 of an X-ray image intensifier tube 50 and a photoelectric body 28. This liquid crystal shutter 52 is designed to be drivable at every range corresponding to one picture element or a picckup unit, for example, in a TV camera 42, and controlled by a liquid crystal shutter controller 54 on the basis of an output signal out of the TV camera 42. With application of an electric field, a polarizing direction of the incident light into a liquid cristal 56 is varied, while brightness and darkness are produced by function of a polarizing plate 62. That is to say, with the presence of voltage impression, it transmits or cuts off the light, functioning as a photoshutter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an X-ray fluorescence multiplier, and particularly to a structure for preventing halation and burn-in caused by excessive X-rays.

[Prior Art] FIG. 5 shows a general configuration of an X-ray fluorescence intensifier tube. In the figure, (A) shows the whole, (B,) shows an enlarged view of area A1 in (A), and (C) shows an enlarged view of area A2 in (A). .

First, in FIG. 2A, the X-rays irradiated onto the inspection object are made to enter from the input surface 12 side of the glass container 10. Inside the glass container 10, an electron beam 14 is transmitted to a focusing electrode 16 and an anode! 8 reaches the output surface 20, and an optical image of the object to be inspected is formed on the output surface 20.

Next, the input surface 12 side of the X-ray fluorescence multiplier tube will be described with reference to FIG. On the side of the X-ray entrance window 22 of the glass container 10, a cathode 24 made of an aluminum substrate is first provided, and then an LG-Csl input phosphor layer 26 that outputs fluorescence in response to incidence of X-rays is arranged. has been done. Further, next to the LG-Csl input phosphor layer 26, a photoelectric material 2 is provided.
8 is arranged, from which electrons corresponding to the incident fluorescence are output.

To explain the operation of the above parts, the X-ray entrance window 22
The incident X-rays are converted into fluorescence by the LG-Csl input phosphor layer 26, and further converted into electrons by the photoelectric material 28. The electrons reach the output surface 20 as an electron beam 14 due to the electric field formed by the cathode 24, focusing electrode 16, and anode 18.

Next, the output surface 20 side of the X-ray fluorescence multiplier tube will be described with reference to FIG. An output phosphor layer 30 made of aluminum foil or the like is provided on the incident side of the electron beam 14, and an output glass substrate 31 is provided between the output phosphor layer 30 and the glass container 10. .

The operation of the above portions will be explained. The electron beam 14 incident on the output phosphor layer 30 by the accelerating electric field formed by the anode 18 and the cathode 24 is converted into fluorescence by the output phosphor layer 30, and this light is transmitted through the output glass substrate 31 and the glass container 10. Output to the outside.

As described above, the X-ray fluorescence intensifier tube has the function of forming an image of the inspection object by X-rays formed on the human power surface 12 side as a multiplied optical image on the output surface 20 side.

Next, an X-ray fluoroscope using the above-mentioned X-ray fluorescence intensifier will be explained with reference to FIG.

In FIG. 6, the X-rays output from the X-ray generator 32 irradiate the inspection object 34, and the X-ray fluorescence multiplier controller 36
The X-rays enter an X-ray fluorescence intensifier tube 38 controlled by the X-rays. The optical image of the inspection object 34 formed by the X IjA fluorescence multiplier tube 38 is then transmitted through an appropriate optical system 40 to the T
The image is captured by the V left camera 2. This image is reproduced on the television monitor 44.

[Problems to be solved by the invention] By the way, the above-mentioned X-ray fluoroscopy is becoming widely used because it allows for faster inspection than methods using film. .

However, the method using an X-ray fluorescence multiplier as described above has a narrow dynamic range, and when excessive X-rays are incident, a large field of light is generated in the input phosphor layer, causing halation. , there is a problem that the input surface 12 and output surface 20 of the X-ray fluorescence multiplier tube 38 are burned.

Therefore, when inspecting a small object as shown in FIG. 6, special measures are required, such as using a mask 46 made of lead or the like to limit the irradiation range of X-rays.

However, such a method cannot be applied to an inspection object having a complicated shape, which poses a major problem.

The present invention has been made in view of the above, and an object of the present invention is to provide an X-ray fluorescence intensifier tube that does not cause halation or burn-in due to excessive X-rays even when inspecting an object of complex shape. That is.

[Means for Solving the Problems] The present invention provides a photoelectric intensifier for an X-ray fluorescence multiplier tube that uses photoelectron emission to form an X-ray image of an inspection object on the input side as a light image on the output side. The device is characterized in that a liquid crystal shutter is provided on the light incident side of the device.

[Function] According to the present invention, even if a large amount of light is generated in the human-powered phosphor layer due to excessive incidence of X-rays, electron emission from the photoelectric means is suppressed by attenuating or blocking the light by the liquid crystal shutter.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the same reference numerals are used for the same components as in the conventional example described above.

FIG. 1 shows an embodiment of an X-ray fluorescence intensifier according to the present invention. In this figure, an X-ray fluorescence intensifier tube 50
A liquid crystal shutter 52 is arranged between the LG-Csl input phosphor layer 26 and the charging body 28 . This liquid crystal shutter 52 can be driven for each area corresponding to one pixel, which is the imaging unit of the TV left camera 2, for example.

The liquid crystal shutter 52 is controlled by a liquid crystal shutter controller 54 based on the output signal of the TV left camera 2, as shown in FIG.

Next, the basic operation of the liquid crystal shutter 52 will be explained with reference to FIG. In the figure (A), a TN type liquid crystal 56 is sandwiched between glass substrates 6o having transparent electrodes 58, and polarizing plates 62 are further provided above and below. These polarizing plates 62 are in a perpendicular Nicol relationship.

Next, the principle of an optical shutter will be explained with reference to FIG. 6B. Application of an electric field changes the polarization direction of the light incident on the liquid crystal 56, and the action of the polarizing plate 62 produces brightness and darkness. That is, depending on whether or not a voltage is applied, light is transmitted or blocked, and it functions as an optical shutter. Such liquid crystal shutters are used as display devices for small televisions.

Next, the overall operation of the above embodiment will be explained. First, as shown in FIG. 4(A), the liquid crystal shutter 52 is brought into a transparent initial state. In this state, the inspection object 34 is irradiated with X-rays as shown in FIG.

When X-ray irradiation is performed, an optical signal corresponding to the amount of transmitted X-rays is incident on the TV left camera 2. Then, an image signal corresponding to this optical signal is manually transmitted from the TV left camera 2 to the TV monitor 44 and the liquid crystal shutter controller 54, respectively.

When the image signal reaches a level that causes halation, the liquid crystal shutter controller 54 makes the corresponding portion of the liquid crystal shutter 52 opaque. This prevents an excessive amount of light from entering the photoelectric body 28 of the X-ray fluorescence multiplier 50.

The above operations are performed on the entire liquid crystal shutter 52,
As shown in FIG. 4(B), the area around the inspection object 34 is masked.

Note that the present invention is not limited to the above-mentioned embodiments; for example, the liquid crystal shutter 52 may be curved along the curve of the human-powered surface 12, as shown in FIG. 5(A). .

[Effects of the Invention] As explained above, according to the present invention, halation and burn-in due to excessive X-rays do not occur even on complex-shaped inspection objects, and the range of application is greatly expanded. effective.

[Brief explanation of drawings]

FIG. 1 is a partially broken sectional view showing an embodiment of the present invention;
Fig. 2 is a block diagram showing an example of an X-ray fluoroscope using the above embodiment, Fig. 3 is an explanatory drawing showing the principle of the liquid crystal shack, Fig. 4 is an explanatory drawing showing an example of masking, and Fig. 5 is an explanatory drawing showing an example of masking. FIG. 6 is an explanatory diagram showing an example of a conventional X-ray fluorescence intensifier, and FIG. 6 is a block diagram showing an example of a conventional X-ray fluoroscope. 26...LG-Csl input phosphor layer, 28...
Photoelectric substance, 30... Output phosphor layer, 32...X
! jA generator, 42...TV camera, 44...
Television monitor, 50...X-ray fluorescence multiplier, 52...
...LCD shutter controller, 54...Night crystal shutter controller.

Claims (1)

[Scope of claims]
An X-ray fluorescence multiplier, characterized in that a liquid crystal shutter is provided on the light incident side of the photoelectric means.