JPS61133543A - Electron tube and its adjustment - Google Patents

Abstract

PURPOSE:To regenerate a correct image by correcting the fixed and variable distortion peculiar to an electron tube by combination of the electron image obtained on the target and the electron beam scanning means comprising an electron gun having a deflection device. CONSTITUTION:A target 23 is provided in the electron tube so as to oppose the input face 22 having the convex face facing an electromagnetic wave generating source 1 side. An electron gun 26 is provided in the back face side of the target 23. The target 23 which is held at the potential equivalent to the anode electrode 25 serves to form an electron image by radiation of the electrons from the input face 22, focused and accelerated by the grid electrodes 24a-24c and the anode electrode 25. The electron image has a coiling distortion peculiar to the electron tube based on the electrode structure. A variable distortion occurs in the electron image when varying the distance between the electron tube and the X-ray generating source 1. The foregoing distortions are corrected as by deflecting the electron beam emitted from the electron gun 26 so that it achieves scanning along the coiling distortion curve 30 of the electron image on the target 23.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention converts electromagnetic waves emitted from an electromagnetic wave generation source such as X-rays through a subject into an electronic image.

The present invention relates to an electron tube that converts this electron image into an electric signal and a method for adjusting the same.

[Technical Background of the Invention] As a system for reproducing and observing a two-dimensional image obtained by irradiating a subject with electromagnetic waves such as X-rays on a monitor TV, there is an X-ray TV system shown in FIG. 4. This X-ray TV system ram Xftlp source (1), the X-ray image intensifier (2) placed in front of this X-ray source (1), and this The optical lens (3
) and a camera tube (4), and a monitor TV (fil) connected via a reproducing circuit (5) that processes signals sent from the camera.

Normally, an image with the following image distortion is reproduced on the screen of the monitor TV f61.

(1) The input surface (8) of the X-ray image intensifier (2) has a spherical shape with the X-ray source (1) side being a convex surface, and X114i! Distortion (2) that occurs because the distance from the source (1) to the input surface (8) is different between the center and the periphery Distortion that occurs in the electron lens system (9) of the Xm image intensifier (2) (3) Distortion caused by the camera's optical lens (3) (4)
These include distortion generated in the image pickup tube (4), (5) distortion generated in the reproduction circuit and monitor TV 16), and the like. Particularly large distortions among these are the attempts (1) and (2) caused by the structure of the X-ray image intensifier (2).

In this X-ray TV system, the monitor 'r v (6
) is essential to correctly grasp the shape, position, etc. of the object 00. In order to remove this image distortion,
Conventionally, an X-ray image intensifier shown in FIG. 5 has been developed. This Xm image intensifier (2+H, input surface (8) and output surface 01) is composed of fiber plates whose opposing surfaces are concave,
Electronic lens system (9) % input surface (8) and output surface 0
1) This is an attempt to reduce image distortion based on the shape of Some devices are configured to have characteristics to cancel out image distortion on the output surface 01).

[Problems in the Background Art] When the X-ray image intensifier (2) is composed of an input surface (8) and an output surface aυ, each of which has a concave opposing surface, the X-ray image intensifier (2) is Compared to the tensifier (2), image distortion based on the structure of these input surfaces (8) and output surfaces 01) can be reduced. However, on the other hand, the fiber plate is expensive, especially if it is configured to serve as a part of the envelope of the Xm image intensifier (2) as shown in Figure 5. The need for thicker fiber plates increases manufacturing costs. The quality of the image also deteriorates. Furthermore, even if the output surface 01) is made concave to reduce image distortion, its shape remains fixed, so the output surface 01) is concave. X-ray image intensifier with variable field of view (2
), when the field of view size is changed, distortion correction corresponding to σ cannot be performed.

The same problem occurs when distortion is corrected using the optical lens (3), and due to changes in the distance from the X-ray source (1) to the X-ray image intensifier (2) and changes in the field of view size. It is not possible to respond to this.

[Purpose of the Invention] The present invention provides an electron tube that forms an image of a subject using electromagnetic waves emitted from an electromagnetic wave source through the subject, which changes in response to changes in distance from the electromagnetic wave source, changes in field of view size, etc. The object of the present invention is to construct an electron tube that can appropriately and easily correct distortion and distortion inherent in the electrode structure of the electron tube.

[Summary of the Invention] The electromagnetic wave generation source side is a convex surface, the input surface converts the electromagnetic waves irradiated from the electromagnetic wave generation source onto the subject into electrons, the lens that focuses and accelerates this 1″, and the child lens. Due to the incidence of the focused and accelerated electrons, the electron image of the object is shaped like f
An electron tube is constituted by a target that is illuminated, and a scanning means that scans the target and converts the electron image into an electric signal.In particular, the target may be a flat plate facing the input surface or a spherical surface whose surface facing the input surface is concave. In addition, the scanning means is configured to scan along the strange curve of the electronic image formed on the target, so that an image with less distortion can be reproduced.

"Embodiments of the Invention" The present invention will be described below based on embodiments with reference to the drawings.

FIG. 1 shows the structure of an electron tube according to an embodiment of the present invention. This electron tube has a spherical input surface (2) inside an X-ray input window (21) constituting one end of the sand.
The hot water is provided with its convex surface facing the X1Ii1 input window (21), and the input surface (21) is provided at the other end of the envelope.
A target e:→ is provided opposite to the target e:→. In addition, inside the envelope (A) between this input surface (221 and Targetera 231), there are arranged cylindrical first, second, and third grid electrodes (24a) in order from the input surface (2 side). (24c) and a cylindrical anode 1 surrounding the target (2)
An electron lens consisting of 1 (g) is provided, and an electron gun (26) for scanning the target (2nd floor) is further provided on the back side of this target Q3).

The X-ray input surface is installed in front of the input surface (X-ray input sensing CI, which has a phosphor and a photocathode sequentially adhered to the concave side of a 221Fi1 spherical X-ray transmitting substrate). The structure is such that a phosphor emits light due to X-rays irradiated from a generation source (11), and electrons are generated on a photocathode corresponding to the emission intensity of the phosphor. Grid electrodes (24a) to (24c)
), the input surface f22) (first grid electrode of II+ (
24a) to 2nd. Third grid electrode (24b).

A higher potential is applied in the order of (24C), and an anode potential higher than that of the third grid electrode (24C) is applied to the anode electrodes 6 and 6. Target Q turbidity is made by applying a 12th electron multiplication effect (8eeondary electron multiplier) to a mesh or thin plate of a metal that is easy to shape, such as a plane, or to a plated plate.
-ductlon) or Electron Bombard Induced
In this example, the dielectric layer is formed into a spherical shape, which will be described later, with its concave surface facing the input surface. ) (231H.

It is held at the same potential as the anode electrode (251, and the upper h1 grid is connected to the electrodes (24a) to (24C) and the anode electrode Q.
An electron image is formed by the incidence of electrons and electrons from the input n- which are focused and accelerated by (2). This electron image is converted into an electric signal by scanning with a child beam emitted from the electron gun b), and is reproduced as an image on a monitor TV via a reproduction circuit.

By changing the potential of the electron tube and the third grid electrode (24e) in stages, the field of view size of the subject 001 placed in front of the electron tube can be changed in multiple stages. Namely, the third grid box, pole (24C)
When a relatively low potential is applied to
3) When a predetermined potential higher than n% is applied, the field of view size is reduced and an electron image of the maximum field of view size is formed. An electronic image is formed that enlarges the central portion of the image.

Since the electron image formed on the input surface (25) is spherical, the distance traveled by the electrons from the input surface 0 to the target (c) is It is different between the center and the periphery, and the focused electric field formed by the finite size grid electrodes (24a) to (24C) is also different between the tube axis +281 and the periphery, so it usually has pincushion-like distortion. . Doi target in this electron tube) c
! The concave shape of i is such that the input surface (
It may have a spherical shape with a concave surface on the second hot water side, but it is preferably a shape that eliminates the fixed φ based on the electrode structure. In more detail, the distortion caused by the electrode structure is most pronounced at the maximum field of view, so
It is preferable to use a shape that optimally corrects distortion in the intermediate area between the largest visual field size or Fi maximum visual field size and the next largest visual field size. Its specific shape can be easily determined based on accumulated data on this type of electron tube and some trial-and-error tests.

Even if the target (23) is formed as described above, the electron image formed on the target (c) will still be affected when the field of view size is changed or between this electron tube and the X-ray source (23).
1) Variable distortion occurs when the distance from the In particular, when the target (2 sides Fi) has a shape that does not completely eliminate the fixed distortion based on the electrode structure, a pincushion-like distortion is generated in which the above-mentioned fixed distortion is added to this variable distortion. Such distortion.

As shown by multiple curves (2) in Figure 2, Yoiichiko Gun (
Correction is made by deflecting the electron beam emitted from 2Q so as to scan along the pincushion-shaped distortion curve (7) of the electron image on the target Q row. This electron beam can be deflected electrostatically or by designing a deflection plate or a deflection coil to form a deflection electric or magnetic field having a similar shape to the pincushion-like distortion of the electron image. , can be done magnetically. This can also be achieved by controlling with a deflection control unit connected to a deflection plate or a deflection coil. In addition, the electrode at the tip is configured so that the electric field between the electrode at the tip of the electron gun (Tagera) 01 and the electron gun (Il) becomes weaker as it goes from the tube axis Q barrel to the periphery, and the potential of this electrode This can also be done by adjusting the beam so that it scans along the distortion curve.Furthermore, by combining two or more of the methods, the scanning of the electron beam can be adjusted more optimally.

To adjust the scanning of the electron beam, as shown in Fig. 3 (Fig. By irradiating X-rays from the X-ray generation source (1), an electron image G3'l of the checkered striped member 02 is formed on the target (2) as shown in FIG.

Then, this electronic image <33) is scanned by an electron gun (a), and this electronic image (alcohol) is reproduced as an image on a monitor TV.

While observing this image, adjust the deflection of the electron beam at the trench that will give you the correct checkered pattern image.

A correct image without distortion is the distortion Iv41 of an electron image in which the electron beam has a checkered pattern! obtained when adjusted to scan along. If it is not necessary to perform this distortion correction accurately, for example, the distance to the X-ray source (1) may be kept constant, and the difference may be caused by switching the field of view size. By correcting the distortion and providing a correction circuit in the control section, it is possible to perform the necessary distortion correction simply by operating a switch on the control section. Moreover, if such distortion correction is performed, it becomes easy to perform precise adjustment afterwards.

Thus, by the combination of the scanning means consisting of the above-mentioned target (an electron gun (branch) having a double concave shape and the above-mentioned specific deflection device), the specific distortion and variable distortion inherent in this electron tube can be corrected. , the correct image can be played.

Next, other embodiments will be described.

In the above embodiment, an electron gun is used as the ij% scanning means.

The electron beam emitted from this electron gun was deflected to scan the target, but instead of this electron gun, a plurality of semiconductor scanning elements V were used to scan the electron image shown in Figure 2 or Figure 3. They may be arranged closely on the back side of the target along the distortion curve Oi to scan the target. In this case, the semiconductor scanning element array is rigid with respect to the target, so it is either the largest field size that produces the greatest pincushion distortion, or an intermediate field size between this largest field size and the next largest field size. It is preferable to arrange them along the distortion curve that occurs in . The spool-shaped distortion curve has 5 intervals going from the center to the periphery of the target,
Therefore, the array of semiconductor scanning elements can be made denser in the center of the target and arranged in layers toward the periphery, or the semiconductor scanning elements arranged in the center of the target can be made smaller and arranged closer to the periphery. It is preferable to increase the size of the semiconductor scanning element to be arranged.

In addition, in the other embodiments described above, the semiconductor scanning elements are arranged along the distortion curve of the electronic image, but a plurality of semiconductor scanning elements are arranged along a straight line in a matrix shape on the back side of the target (2). The scanning control section may control each semiconductor scanning element to operate along the distortion curve of the electronic image.

Although this scanning means has a more sophisticated scanning control section than the above embodiment, the scanning can be adjusted to match the variations in the electronic image formed on the target, and a correct image is always reproduced. In the above embodiment, the target is formed into a spherical shape with a concave surface on the input surface side, but the present invention can also be applied to a case where the target is flat. , a variable field of view electron tube with three grids t& (although the present invention has been described with reference to two electron tubes), the present invention can also be applied to an electron tube with a fixed field of view.

[Effects of the Invention] The output section of an electron tube used in a system for observing an image obtained by irradiating an object with electromagnetic waves such as X-rays can be made into a spherical shape in which the surface facing the input surface is flat or concave. It consists of a target, and the scanning means for scanning this target is configured to scan along the distortion curve of the electron image formed on this target. Variable distortions caused by changes in size or distance from the electron tube to the electromagnetic wave source can be easily corrected, and correct images with less distortion can be reproduced.

(21m, based on the electron image obtained on the target by irradiating electromagnetic waves through a checkered member that is opaque to magnetic waves, the scanning means is adjusted to scan along the distortion curve of this electron image. , it is possible to easily and correctly correct the distortion of the electronic image formed on the target.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an electron tube according to an embodiment of the present invention.
Figure 2 is a diagram showing the target scanning of the electron gun incorporated in the first illustrated electron tube, and Figures 3 (5) and (H) are the first
Figure 4 is a diagram for explaining the adjustment method of the electron tube, and the two-dimensional image obtained by irradiating the subject with X-rays is
I = Configuration diagram of a conventional system for reproducing and observing, 5th
The figure is a diagram of a conventional X-ray image intensifier. (1)...X-ray source α1...Subject@...
・Input surface (c)・-Target (24a)・
...First grid electrode (24b)...Second grid electrode (24C)...Third grid electrode (c)...Anode electrode (261...Electron gun 0
No... Plaid member

Claims (10)

[Claims] (1) An input surface with a convex surface facing the electromagnetic wave source side, which converts the electromagnetic waves emitted from the electromagnetic wave source through the subject into electrons, an electron lens that focuses and accelerates the electrons, and a surface facing the input surface. is formed into a flat or concave spherical shape, and an electronic image of the object is formed by the incidence of the focused and accelerated electrons, and the target is scanned along a pincushion curve to form the electronic image. An electron tube characterized in that it is equipped with a scanning means for converting an electric signal into an electric signal. (2) The electron lens has an electrode that changes the field of view size in multiple stages, and the concave shape of the target forms a curved surface that optimally corrects the pincushion distortion of the electronic image in a field of view size larger than the minimum field of view size. An electron tube according to claim 1, characterized in that: (3) The electron tube according to claim 1, wherein the scanning means includes an electron gun that emits an electron beam toward the target and scans the electron beam in a pincushion shape using a magnetic field. (4) Scanning means 1 An electron tube according to claim 1, further comprising an electron gun that emits an electron beam toward a target and scans the electron beam in a pincushion shape using an electric field. (5) The electron tube according to claim 3, wherein the electron gun has an electrode that weakens the electric field between the electron gun and the target as it goes from the center to the periphery of the target. (6) The electron tube according to claim 1, wherein the scanning means has a plurality of semiconductor scanning elements arranged in a matrix on the target along a pincushion-shaped curve. (7) The electron tube according to claim 6, wherein the plurality of semiconductor scanning elements are spaced apart from each other as they go from the center to the periphery of the target. (8) The electron tube according to claim 6, wherein the plurality of semiconductor scanning elements are small at the center of the target and large at the periphery of the target. (9) The scanning means has a plurality of semiconductor scanning elements arranged in a matrix on the target along a straight line, and a control device that controls the operation of these semiconductor scanning elements along a pincushion-shaped curve. An electron tube according to claim 1, characterized in that: (10) An input surface that has a convex surface facing the electromagnetic wave source and converts the electromagnetic waves emitted from the electromagnetic wave source into electrons, an electron lens that focuses and accelerates the electrons, and an electron image is formed by the incidence of the focused and accelerated electrons. A plaid member opaque to the electromagnetic waves is disposed in front of an electron tube having a target and a scanning means for scanning the target and converting the electron image into an electrical signal, and the electromagnetic waves are transmitted from the electromagnetic wave generation source through the plaid member. An electron tube comprising: a method of irradiating electromagnetic waves to form an electron image of the checkered member on the target; and a method of adjusting the scanning means so as to scan along a distortion curve of the electron image. How to adjust.