JPH0334242A - Image intensifier tube - Google Patents

Abstract

PURPOSE:To enhance a reduction in electron orbit deflection by providing a deflection correcting anode electrode between a screen electrode and an anode electrode. CONSTITUTION:The electrons generated from the photoelectric surface of an input surface 2 according to the input of a subject image signal are focused and accelerated by focusing electrodes 41-43 and an anode electrode 51, and taken out from a screen electrode 3. A deflection correcting anode electrode 52 having nearly the same inclined surface as an electron orbit surface to which a potential lower than that to the electrode 51 is added is also provided between the electrodes 51 and 3. According to this simple constitution, an electron orbit deflection which is exponentially increased as it is closer to the periphery can be remarkably suppressed, and the whole deflection is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an II (image intensifier) tube with reduced output image distortion.

``Prior Art'' In general, as shown in FIG. 3, an X-ray II tube has an input surface (2) at one end of a cylindrical envelope (1) and an input surface (2) at the other end opposite to this human power surface (2). An output surface (3) and a focusing electrode (4□) (4) provided between the input surface (2) and the output surface (3).
□) (4,) and an anode electrode (5) provided near the output surface (3).

In such a configuration, X-rays from the X-ray source (6) pass through the subject (7) and cause the phosphors on the input surface (2) to emit light, and this light emission causes photoelectrons formed on the input surface (2) to emit light. Generates electrons from the surface. Then, these electrons are focused by the electrode (4□)
(4a), (4z) and the anode electrode (5), the light is focused and accelerated to be incident on the output surface (3), and the phosphor on the output surface (3) emits light to obtain an output.

However, in this type of XI&II tube, since the input surface (2) is spherical and the output surface (3) is flat, pincushion distortion as shown in FIG. 4 occurs. That is, what should be a linear lattice shape as shown by the dotted line becomes a curved characteristic as shown in the solid line, and the peripheral part of the image is enlarged compared to the center part of the image.

Note that distortion is defined as follows.

D.

Here, Do: reduction ratio of the length of the center 1o of the input surface (2), Dp reduction ratio at a position of a straight line from the field of view dimension of the entrance surface for two people, and the field of view dimension of the entrance surface d is given by the following formula. required from.

α d = d2・Q+s Here, dl: Field of view dimension of the incident surface d2 = Dimension of the input surface (2) Q2 l Distance from the IA source (6) to the incident surface S: Input surface (
2) Position ``Problem to be solved by the invention'' The conventional X-ray II9 had large distortion in the peripheral area, making it difficult to accurately judge the size of the object in the peripheral area, and the output luminance There was a problem of poor uniformity. That is, the characteristic curve indicated by the dotted line in FIG.
It represents the characteristics of an I-tube, and shows the relationship between the radius of the input surface on the horizontal axis and the strain on the vertical axis when the input surface is 310Dlφ and the output surface is 25mφ.The strain includes electron orbital strain and geometric strain. There is a total distortion of these.

Of these, geometric distortion occurs due to the structure, and electron orbital distortion occurs due to the potential of the focusing electrode, electrode shape, etc.

It is clear from FIG. 5 that the electron orbit distortion increases exponentially and the overall distortion increases as the area approaches the periphery.

The object of the present invention is to reduce electron orbital distortion as much as possible.

"Means for Solving the Problems" The present invention involves inputting a subject image signal into an input surface at one end of an envelope, and focusing and accelerating electrons generated from a photocathode on the input surface using a plurality of focusing electrodes and an anode electrode. In the device in which the output is taken out from a screen electrode on the output surface at the other end of the envelope, a lower potential than these electrodes is applied between the screen electrode and the anode electrode to change the output image. A second anode electrode is interposed to correct distortion.

"Operation" In the X-ray II tube, X-rays emitted from the X-ray generator pass through the subject and are irradiated onto the human surface. Then, the phosphor on the human-powered surface emits light, electrons are generated from the photocathode formed on the input surface, and these electrons are focused and accelerated by a plurality of focusing electrodes and an anode electrode and enter the output surface. At this time, the electron trajectory in the peripheral portion is corrected by the second anode electrode between the anode electrode and the screen electrode on the output surface. As a result, distortion in the peripheral portions is reduced.

"Example" Hereinafter, one embodiment of the present invention will be described based on the drawings.

In Figure 2, (1) is an envelope, and this envelope (1)
An input surface (2) is provided at one end of the enclosure (1).
) is provided with a screen electrode (3) as an output surface. Furthermore, on the inner circumference of the envelope (1), there are three focusing electrodes (
4□) (4□) (43), first anode electrode (5,),
Second anode electrodes (5□) are sequentially provided. Among these electrodes, the most important feature of the present invention is the second anode electrode (5,) between the first anode electrode (5,) and the screen electrode (3).
An anode electrode (5,) is provided, and this second anode electrode (5,) is provided.
52) is provided with a lower potential than the first anode electrode (51) or the screen electrode (3). Moreover, as shown in FIG. 1, this first anode electrode (51)
, a thin plate-shaped first anode protrusion (8
), and the second anode electrode (5, ) has an inclined surface (9) for correcting electron trajectories. The first anode protrusion (8) protrudes approximately perpendicularly to the electron trajectory side so as to have an effect only on the peripheral portion where the potential by the second anode electrode (5□) is to be corrected.

The operation of the above configuration will be explained.

The potential applied to each part is 1. For example, as shown in Figure 2, the input surface (
2) photocathode is O■, 1st. Second. Third focusing electrode (4,
)(4, )(4:I) are ll0V and 860V, respectively.
.

3.8KV, the first anode electrode (51) is 25KV, the second anode electrode (52) is 20KV, the screen electrode (
3) is 25KV.

In this state, the electrons generated from the photocathode of the human power surface (2) are focused and accelerated at the first to third focusing electrodes (4□) to (4,),
And the electron trajectory is corrected by the second anode electrode (5,) (5□), and the electron trajectory is made to enter the output surface (3).
) to emit light to obtain an output image signal.

The first and second anode electrodes (5□) (5□), especially the second anode electrode (5□), have an inclined surface (9) that is approximately the same as the electron orbital surface, so that the peripheral part of the electron orbit is Corrected to suppress it. The solid line characteristic curve in FIG. 5 represents the characteristics of the X-ray II tube according to the present invention, and shows the relationship between the input surface radius on the horizontal axis and the strain on the vertical axis. Comparing with the characteristics of the conventional X-ray II tube (dotted line), the conventional tube has an electron orbital distortion of 5.5% and a total distortion of 11% at the end of the input surface, whereas the XIIIA II tube of the present invention has an electron orbital distortion of 2%1. The total distortion is significantly reduced to 7.5%.

In the above embodiment, the case of the X-ray II tube was explained, but
Photoelectrons are generated by the light beam incident on the input surface (2),
Of course, it is also possible to use a general II tube which intensifies this and obtains an output image on the output surface.

"Effects of the Invention" As described above, the present invention includes a second anode electrode interposed between the screen electrode and the anode electrode, and a lower potential than the first anode electrode or the screen electrode is applied to the second anode electrode. Since this is added, the peripheral portion of the electron trajectory immediately before entering the output surface is corrected. Generally, the strain increases exponentially toward the periphery; however, in the present invention, the electrode structure is particularly effective in the periphery, so a 1-inch tube with low strain can be obtained.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the main part of the X1II tube according to the present invention;
The figure is a cross-sectional view of the same as above, Figure 3 is a cross-sectional view of a conventional X-ray II tube, Figure 4 is an explanatory diagram of distortion, and Figure 5 is a conventional (dotted line) and the present invention (solid line) X-ray II tube. FIG. (1)...Cylindrical envelope, (2)...Input surface (photocathode), (3)...Output surface (screen electrode), (41)~
(43)...Focusing electrode, (5)(5,)(52)...
- Anode electrode, (6)...Radiation source, (7)...Subject, (8)...Protrusion portion, (9)...Slope portion.

Claims (3)

[Claims] (1) Inject the subject image signal into the input surface of one end of the envelope,
Electrons generated from the photocathode on the input surface are focused and accelerated by a plurality of focusing electrodes and an anode electrode, and an output is taken out from a screen electrode on the output surface at the other end of the envelope, wherein the screen electrode An image intensifier tube characterized in that a second anode electrode is interposed between the anode electrode and the second anode electrode for applying a lower potential than these electrodes to correct distortion of an output image. (2) The image intensifier tube according to claim (1), wherein the second anode electrode has an inclined surface substantially the same as the electron orbital surface. (3) The image intensifier according to claim 1 or 2, wherein the first anode electrode has a first anode protrusion extending to approximately the same position as the tip of the inclined surface of the second anode electrode. tube.