JPH0358135B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image pickup tube for a television camera, which uses an MS type (electromagnetic focusing, electric field deflection) focusing/deflection method to further reduce the size and power consumption of the image pickup tube. At the same time, the aim is to achieve ultra-high performance.

In conventional image pickup tubes, as seen in the MS type, MM type (electromagnetic focusing, magnetic field deflection), and SM type (electric field focusing, magnetic field deflection), image quality such as resolution and distortion is affected regardless of the focusing/deflection method. Due to the need to ensure uniformity, the length of the focusing deflector is, for example, 90 mm and 11 mm for a beam raster diameter of 16 mm.
The diameter of the beam raster is designed to be approximately 64 mm, and the ratio of length to diameter of the beam raster is required to be over 5.5, and has been put into practical use.

In order to make the image pickup tube compact, the diameter is 8 to 10 mm, which is practically small due to constraints on the lens optical system and the need to ensure the resolution of the target photoconductive film.
Since the diameter is the limit, the only way to reduce the size is to shorten the length of the tube.

There are two ways to shorten the length of the tube: one is to fill up the extra space inside the tube, and the other is to increase the deflection angle and shorten the electron-optical deflection area.
There are two possibilities.

However, the latter method of increasing the deflection angle inevitably deteriorates the image quality as the deflection angle increases.

An example of this type of attempt is a conventional MM type beam raster with a diameter of 11 mm and a deflector length shortened by about 20% from 64 mm, such as the Hitachi 2/3 inch Sachicon H9336. Due to the shortening, the central resolution is 60% in both cases, while the peripheral resolution is
It will drastically decrease from 25% to 10%. On the other hand, the geometric distortion is 1
% to 1.5%. If the SM type was similarly shortened, the peripheral resolution would drop to almost zero, making it nearly impossible to maintain image quality.

Furthermore, shortening the tube requires increasing the focusing electromagnetic field in inverse proportion to the tube length, and the power required for focusing and deflection increases in inverse proportion to the square of the length.

It is said that the uniformity of the image quality of the MS type is better than that of other focusing/deflection methods (for example, TV Science and Technology Report vol.5,
No. 10 (July 1981), pp. 19-36), and is generally considered to be a method that is resistant to large angle deflections.

However, simply shortening the length will inevitably lead to deterioration in image quality. For this reason, there has been no study on shortening the MS type in the past.

The present invention was made based on the knowledge that shortening the MS type would result in higher performance.In addition to shortening and downsizing the MS type, the shape of the deflectron pattern was also improved, making it possible to improve the performance of the MS type. The object of the present invention is to provide an electromagnetic focusing electric field deflection type image pickup tube with ultra high performance.

In order to achieve such an object, the present invention provides a plurality of deflectron electrodes arranged on the inner surface of the glass outer tube, an electron gun arranged at one end of the glass outer tube, and an electron gun arranged at the other end of the glass outer tube. a light-receiving face plate placed outside the target, a mesh electrode placed inside the target, and a focusing electromagnetic coil placed around the glass outer tube; In an image pickup tube that has a focusing deflector configured to form a collimation lens in the gap between the electrode and the mesh electrode and performs electromagnetic focusing and electric field deflection, a deflection pulse is superimposed on the deflectron electrode to In order to compensate for the fact that the collimation lens formed between the mesh electrode and the deflectron electrode becomes effectively weaker as it moves away from the tube axis of the focusing deflector in the radial direction, the deflection pulse A strong lens is formed in the state where the image pickup tube is cut off, and the imaging magnification of the image pickup tube is reduced. Furthermore, in order to provide an image pickup tube with excellent performance such as uniform resolution characteristics, small figure distortion, and reduction in deflection power, the present invention also improves the pattern of the deflection electrode. It is something.

The present invention will be explained in detail below with reference to the drawings.

1A to 1D show the basic configuration of the image pickup tube of the present invention, where 1 is an electron gun section that generates an electron beam, and 2 is an electron gun section 1 that is accurately held in a glass outer tube 3. 4 is a reflection plate electrode provided on the electron gun side end face of the deflectron 5 for terminating the electric field; 6 is formed on the glass outer tube 3 and is placed near the electron gun section 1; 5 is a deflectron electrode made of a metal thin film provided on the inner surface of the glass outer tube 3 like the lower ring electrode 6; 7 is a deflectron electrode at the end of the deflectron electrode 5 on the target 8 side; Closely, outer tube 3
9 is a mesh base for holding the mesh electrode 10 fixed to the end surface of the outer tube 3; 11 is a device for maintaining vacuum tightness in the tube and for maintaining the mesh electrode 10 and the target 8; The indium ring 12 used for lead extraction is an intermediate glass cylinder inserted between the two indium rings 11, and 13 is an electromagnetic coil for focusing arranged around the glass outer tube 3. , 14 is a collimation lens, 15
is a stem, 16 is a center of deflection, and 17 is a drawing board.

The electron beam 21 emitted from the electron gun section 1 is deflected by the deflectron 5 and bent by an angle α, and is then bent by the mesh electrode 10 and the mesh base 9,
The light is then collimated by the upper ring electrode 7 and the convex lens 14 formed on the end face of the deflectron 5, and is made to enter the target 8 perpendicularly.

If the deflectron is expanded, for example, Fig. 1D
Assume that the pattern has a pitch l _{p and} a twist angle θ _e as shown in .

The requirements for making the MS-type focusing deflector with such a basic configuration compact and high-performance will be described below.

The present invention provides an MS type collimation lens 14.
However, as described below, unlike the conventional MM type,
This was achieved by actively taking advantage of the fact that the pipe becomes weaker as it moves away from the axis of the pipe.

The MS and other collimation lenses 14 are formed between the mesh electrode groups 9, 10, and 7 and the four-divided deflectron electrode 5 on which the deflection pulse is superimposed on the DC voltage _ECD .

On the axis, the positive and negative deflection pulses always cancel each other out and become zero, so the electrode structure and
A lens is created that is statically determined only by E _CM /E _CD . However, off-axis, due to the influence of the superposition of deflection pulses that change at a constant period determined by the television system, different lenses, that is, quadrupole lenses, are formed in the vicinity of the four deflectron electrodes 5. .

If the equipotential lines in the vicinity of the mesh electrode 10 are determined at a certain moment, they become non-axially symmetrical, as shown in FIG. Become something. Therefore, the equipotential line density in the portion to which the positive deflection pulse is applied becomes coarse, and the electric field that is the source of the lens effect becomes weaker. Therefore, a weak convex lens is formed near the deflectron electrode to which a positive deflection pulse is applied, and a strong convex lens is formed in a part to which a negative deflection pulse is applied. Such a quadrupole lens is
Since the location of its strength changes depending on the deflection pulse, it becomes a dynamic lens that moves, just like a human eyeball that moves around a lot.

By the way, since the electron beam 21 is always deflected toward the deflectron 5 to which a positive deflection pulse is applied, in the vicinity where collimation is required, it is more effective than a lens that is always statically formed on the axis. It is only affected by weak lenses.

Therefore, in order to make the beam 21 perpendicular to the target 8 during operation of the deflectron 5, it is necessary to make the static collimation lens that is obtained when the deflection pulse is cut off stronger in advance. There is. In other words, a statically strong lens is created by increasing E _CM /E _CD in advance, and the required lens conditions are only satisfied when a deflection pulse is applied and the lens action is effectively weakened. do.

This becomes clear when comparing the optimal collimation lens when the same tube is operated in MS operation and in MM operation, as shown below.

As is well known, the strength of the collimation lens is
It depends on the above-mentioned electrode structure and applied voltage, and when the electrode structure is kept constant, the voltage between the electrodes becomes stronger as the voltage increases.

Furthermore, since the trajectory of the beam also depends on the focused magnetic field distribution, the conditions for vertical landing also depend on the focused magnetic field distribution, which will be described later.

Curves A and B in FIG. 3 show the optimum strength of the collimation lens 14 (lens The voltage E _CM of the mesh 10 and the DC voltage E _CD of the deflectron 5 (conditions such as aligning the focal point with the center of deflection, ensuring vertical incidence of the beam, and preventing the occurrence of turret wave phenomena) are (A deflection pulse is superimposed on top of E _CD ) was determined for l ₂ /d=0.24 and 0.12, respectively. From Figure 3,
It can be seen that a lens with a short focal length is required in inverse proportion to l/d.

However, the required strength of the collimation lens is abnormal compared to the conventional MM type (magnetic field focusing, magnetic field deflection) and SM type (electric field focusing, magnetic field deflection) due to the above-mentioned reasons and the experimental facts shown in Figure 3. It turns out that something strong is essential.

That is, when the ratio of the length l and the diameter d of the deflectron 5 is l/d=28 and d=16 mm in FIG. 1B,
When l ₁ =0.5 mm and l ₂ =4 mm, the optimum value of E _CM /E _CD is around 700V/300V as shown in FIG. MM operation of the same tube (cutting off the deflection pulse to the deflectron and adding deflection by the magnetic field)
This is because the optimal value is around 500V/300V.

The present invention makes use of the above-mentioned discovery that the collimation lens becomes effectively weaker in the periphery to effectively strengthen the collimation lens in the periphery, which is essential for ensuring normal operation of the image pickup tube. The conditions for forming a collimation lens necessarily lead to the formation of a strong static lens, which, as will be explained later, leads to a reduction in the imaging magnification of the focusing lens system and increases the height of the tube. This was done by taking advantage of the advantages such as increased resolution.

In order to obtain more of the above-mentioned advantages, it is necessary to emphasize the phenomenon in which the collimation lens effectively weakens in the periphery.To do this, the voltage of the superimposed deflection pulse can be relatively reduced by lowering _ECD . It is necessary to prepare conditions such as an electrode structure that can be made large, and that allows E _CM to be as high as possible compared to E _CD to form a strong convex lens.

In order to satisfy this condition, the first thing to do is to make l/d as small as possible while maintaining the required image quality by taking advantage of the fact that the voltage of the required deflection pulse increases in inverse proportion to ^l2 . is necessary.

Hereinafter, suitable conditions for l/d will be described. Figure 4 shows the deflectron 5 when l ₂ /d=0.24.
Changes in the resolution AR, figure distortion, and deflection voltage at the center and periphery of the screen were determined by changing the ratio between the length l of the deflector 5 and the diameter d of the deflectron 5.

The resolution at the center increases as l/d becomes smaller, but becomes saturated when it becomes smaller than 25.
On the other hand, the resolution at the corner increases until l/d is around 3, but deteriorates when it becomes smaller than that.

This is because when l is made small, the following phenomenon occurs.

() Figures A, B, C, and D show the outline of the electric field formed inside the deflectron as l/d changes to 4, 3, 2, and 1, respectively. As the length becomes shorter, disturbances caused by the mesh 10 and the reflector 4 on the end face become relatively more noticeable. According to detailed analysis, the disturbance caused by the end electrode is caused by the diameter d of the deflectron 5.
It was found that the distance was approximately equal to that of the distance that penetrated into the interior. Therefore, even if l is made small, unless l/d is 2 or more, it will not be possible to secure a space for a uniform deflection electric field, and the deterioration of characteristics will increase to a practically unacceptable level.

() Generally, as the deflection angle α increases, the aberration received by the focusing lens increases (for example, figure distortion is proportional to α ³ ), and the uniformity of the imaging state of the beam 21 deteriorates around the screen. Therefore, even though the MS type has the characteristic of uniform resolution, there is a lower limit to the deflection angle α, that is, l/d. Figure 4 shows valuable experimental results that are essential for determining the lower limit.

() In Figure 6, with l/d constant (≒2.8), E _CD
= 300V, and the change in AR when E _CM /E _CD is changed regardless of the setting of the optimal strength of the collimation lens 14.
The larger E _CM /E _CD and the stronger the collimation lens 14, the greater the resolution both at the center and at the periphery.

This is because the imaging magnification of the electron beam 21 emitted from the electron gun section 1 onto the target 8 strongly depends not only on the focusing electromagnetic coil 13 but also on the collimation lens 14, as if the magnification of a microscope etc. This is because it is determined by the synergistic effect of the two, just as it is determined by the product of the magnifications of the objective lens and the eyepiece lens.

In the experiment shown in Fig. 6, the absolute value of E _CM is caused by beam bending (a phenomenon in which the beam is locally bent and attracted toward the target surface, which has a more positive potential when light hits it). This is a harmful phenomenon that causes a decrease in resolution, and the larger the potential difference between the target and the mesh, the smaller this beam bending. It will be done. However, when the strength of the collimation lens 14, that is, E _CM / E _CD is kept constant, only E _CM is set at 300 V to 1500 V.
When I changed it between, there was little change in resolution. Therefore, it is concluded that the influence of beam bending is small compared to the effect of the collimation lens.

For the three reasons mentioned above, the experiment shown in Figure 4 clearly expresses the characteristics of the MS type.As d becomes smaller, a stronger collimation lens becomes necessary, which increases the imaging magnification. On the other hand, if l is made too small, deflection aberrations due to large deflection angles and disturbances in the deflection electric field at the deflectron end face become noticeable, and the peripheral It is concluded that this causes deterioration of resolution and graphic distortion. However, it is also concluded that the limit to which l can be reduced is much smaller than that of the conventional type even if the characteristics are maintained.

Furthermore, although the deflection pulse voltage increases inversely proportional to ^l2 , the increase in power consumption in the drive circuit is slight due to the high impedance of the deflectron, and furthermore, the intensity of the focusing magnetic field is inversely proportional to l. However, since the length of the focusing electromagnetic coil 13 can be reduced in proportion to l, the increase in power consumption in the coil 13 is also negligible, as will be described later. The MS type also has the advantage that the increase in power consumption for driving the tube is small.

In the present invention, as shown in Figure 4, in the MS type focusing/deflecting system, the best condition for obtaining uniform high resolution over the entire screen is to reduce l/d, contrary to the conventional design guidelines. Set it to about 2.0 to 3.5.

Conventionally, since the advantage of reducing l/d had not been discovered, it was thought that l/d should be 4 or more from the standpoint of obtaining uniform resolution. but,
This has the disadvantage that only a low resolution can be obtained over the entire screen.

The desirable l/d of the MS type has been described above, and methods for further improving the characteristics within the desirable l/d range will be described below.

The first is how to set the focusing magnetic field.

FIG. 7 shows the focused magnetic field distribution required for the image pickup tube of the present invention corresponding to each part of the image pickup tube, where 5A is the center position of the deflectron 5, and 8A is the center position of the target 8.
The position 18 is the position of the beam restriction hole, and the horizontal axis indicates the distance from the outer surface of the face plate 17. Curve A in the figure is an example of the focused magnetic field distribution used in the measurement described above. Curve B is an example of a conventionally used focused magnetic field distribution.

In general, if the magnetic field near the target 8 is strengthened, the imaging magnification will decrease and the AR will increase, but on the other hand, aberrations will increase, and shape distortion in particular will deteriorate.
At the same time, the optimum value of E _CM /E _CD also decreases. On the other hand, the magnetic field in the vicinity of the target also acts on the collimation of the beam, and as the magnetic field becomes weaker and the lines of magnetic force diverge more, it becomes necessary to make the collimation lens 14 stronger.

In order to further enhance the effect of setting the above-mentioned MS-type strong collimation lens 14, the present invention focuses on setting the focusing magnetic field distribution so as to enable the setting of an even stronger collimation lens. This is what I did.

An actual measurement example of the effect of such attention brought about by the magnetic field distribution shown in FIG. 7 will be described below. The optimal E _CM /E _CD for the magnetic field distribution of curve B in the same figure is 1.7.
On the other hand, for curve A in the same figure,
It was 2.4. Center AR is 60% for distribution B, distribution A
So it was 70%.

The reduction of the focused magnetic field at the target area is
In the MS type, it actually works to improve the characteristics.

On the other hand, the magnetic field at the beam restriction hole on the electron gun side has almost no effect on figure distortion, and is only related to the magnitude of AR, but its influence is smaller than that on the target side. For example, if the distribution on the electron gun side is increased to curve B or C with respect to the distribution shown by curve A in FIG. 7, the AR will decrease by several percent.

This is because the lines of magnetic force diverge from the vicinity of the electron gun toward the target, broadening the trajectory of the electron beam and increasing the imaging magnification.

Therefore, it is desirable to lower the magnetic field at the electron gun beam limiting hole as much as possible, at least to reduce the peak value.
It is desirable to keep it below 50%.

The setting of the focused magnetic field distribution that brings about the above effect is as follows:
As a result of various experiments, the peak was placed almost at the center of deflectron 5, and the value at target 8 was set to the peak.
It has been found that it is preferable to set the value to 0.2 or less (compared to 0.25 or more for the conventional type), and to set the peak value to 0.5 or less at the electron gun beam limiting hole, and to change it approximately in a Gaussian distribution between them.

Next, it will be described that the preferred setting conditions for l/d in the present invention described above also contribute to reducing the power consumption of the focusing coil 13.

FIG. 8 shows that by changing the ratio l ^* /d ^* between the length l ^* and the diameter d ^* of the focusing coil 13, the magnetic flux density B _zp at the axial center of the focusing coil 13 and the ends (inlet and outlet )
This figure shows the changes in the value B _zpf required for focusing and _{the power P f consumed} by the coil 13 when the on-axis magnetic flux density B zpe is constant, l=constant. In addition,
B _p is the magnetic flux density at the axial center of the infinite length coil,
Each of the above magnetic flux densities is shown as a relative value to this. B _zp decreases as l ^* becomes smaller, as the contribution from coils away from the center decreases, but when l ^* / d ^* is
Even if you shorten it by half from 2 to 2, it will only reduce by about 21%. On the other hand, _Bzpe will only decrease by about 8% due to the same reason.

On the other hand, the magnetic velocity density B _zpf required for focusing the beam 21
must be increased in inverse proportion to the deflectron length l. Therefore, if we shorten it to match l ^* ,
Since B _zp needs to be increased by the increment of B _zpf , P _f also increases. On the other hand, since the number of windings in the coil decreases in proportion to l ^* , P _f decreases accordingly. Therefore, since the increases and decreases in both are canceled out, the actual increase in P _f is increased by the loss due to the shortening of l ^* of B _zp and B _zpe . The loss of B _zp and B _zpe is l ^* / d ^* is 2
It is small until it reaches 2, and suddenly becomes noticeable when it goes below 2.
Therefore, the above-mentioned desirable l/d range is important from the viewpoint of power saving of the focusing coil. Furthermore, since selection of the above-mentioned desirable magnetic field distribution is also a condition that allows shortening of the focusing coil, power saving is emphasized in this sense as well.

Furthermore, in the present invention, the following ideas are added to the electrodes forming the collimation lens 14.

9A and 9B show the strength of the collimation lens 14 depending on the length of the upper ring electrode 7, and as shown here, the collimation lens 14 is
It changes depending on the length l ₃ of the upper ring electrode 7, and becomes weaker as l ₃ becomes longer. An example of this change is in the third
l/d and optimal with l ₂ as a parameter shown in the figure
In relation to E _CM /E _CD , the difference between curve B where l ₂ is 2 mm and curve A where l ₂ = 4 mm is noticeable. For example, when l/d is 2.8, the former's optimal E _CM /E _CD is 1.7, while the latter is 2.3.
becomes.

Therefore, the longer l ₂ is, the more the above-mentioned desirable conditions can be achieved. However, the effect of lengthening l ₂ is at most up to l ₂ =d, and even if it is lengthened beyond that, the collimation lens 14 will not change.

For the reasons stated above, in the present invention, the distance l ₁ between the deflectron electrode 5 and the upper ring electrode 7 is set to 0.5 mm or more, or at most 2 mm, in consideration of the withstand voltage between the two electrodes.
After securing about mm, the upper ring electrode 7 is arranged on the glass outer tube 3 in the same way as the deflectron electrode 5, and l ₂ /d is selected to be 0.15 to 1.

Furthermore, in the present invention, the characteristics can be further improved in the following manner. first,
Considering the selection of the deflectron pattern, Fig. 10 shows the twist angle θ _e of the pattern of Fig. 1 D.
Changes in resolution and graphic distortion were determined by changing the . Curves A, B, C and D are, respectively,
l/d=2.8 for center, l/d=2.8 for corner, l/d=
4 shows the corner AR at the center l/d=4, and curve E shows the figure distortion at l/d=2.8. As seen in the figure, it is best to set θ _e at around 90° in terms of ensuring resolution and uniformity. Shape distortion is also AR
Similarly, it is best when θ _e is around 90°.

In a practically used image pickup tube, the peripheral AR should be at least 1/2 that of the center, and the figure distortion should be at least 1/2 that of the center.
Since 3 TV lines or less are required, it is desirable to set θ _e to 90°±45° from FIG. 10.

Figure 11 shows the change in the required deflection voltage with respect to θ _e . In the range of θ _e mentioned above, the deflection voltage is θ _e
is smaller than when it is 0, and there is also the advantage that deflection power can be saved at the same time.

Note that the above-mentioned FIGS. 3, 4, and 6 were measured under the condition of θ _e =90°.

Next, the pitch l _p of the deflectron pattern shown in FIG. 1D is selected as follows. In other words, in Figure 12, by changing the pitch l _p , d≒16 mm, l
= 45 mm, θ _e = 90°, peripheral AR (AR at the center
(relative value with 1), figure distortion, and changes in deflection voltage are measured. As l _p increases, the figure distortion increases, but the peripheral AR and deflection voltage do not change much. The reason for this is that l _p is d
If the pattern is relatively large, it is necessary to arrange it so as to accurately match the end face of the pattern 5.

However, (a) an electrical short circuit is not allowed between the reflector 4 and the deflectron 5, and (b) after the electron gun block 1 including the reflector 4 is assembled to the stem 15, the glass outer tube 3 It is fixed by welding to the lower part, but the welding precision of the glass is insufficient and only about ±0.1mm can be secured.(c) The reflector 4 is heated to several hundred degrees Celsius during exhaust, so the outer tube 3 and It is difficult to ensure the above-mentioned conditions for reasons such as the need to avoid mechanical contact at all costs since it causes cracking of the outer tube 3 due to thermal shock.

To overcome this difficulty, the lower ring electrode 6 is arranged on the inner surface of the glass outer tube 3 in the same way as the deflectron 5, and it is kept at the same potential as the reflector plate 4. What is necessary is to prevent the unevenness of the end face electric field due to this.

A specific example of the lower ring electrode 6 is shown in FIG.
As shown in FIG. 2, a vapor-deposited film is formed on the inner surface of the outer tube 3 in the same manner as the deflectron pattern, and the gap _l4 with the deflectron 5 is set to a value necessary to ensure pressure resistance, for example, around 0.5 mm. good.

As is clear from the above description, the following effects can be obtained in the present invention.

() The length of the MS image pickup tube can be shortened to 50 to 70% of that of conventional types, making it possible to create ultra-small imaging devices.

() For example, a 2/3-inch type has a resolution comparable to a conventional 1-inch type, that is, the center resolution is 70%.
As described above, since it is possible to ensure a peripheral resolution of 50% or more and a figure distortion of 0.3% or less, it is possible to realize a device with ultra-high performance that surpasses that of large tubes despite being miniaturized.

() Since this ultra-high performance can be obtained by improving only the focusing and deflection system, a sufficiently high-resolution device can be obtained even with an ordinary electron gun using an oxide cathode.

() The increase in focusing and deflection power associated with shortening is at most
Since the increase is only 30%, devices with low power consumption can be realized.

() By combining a high-resolution electron gun with the compact high-performance focusing deflector of the present invention,
For example, it is possible to realize a compact, high-performance imaging device that can be used in high-definition television.

() The arrangement of the lower ring electrode can further reduce the negative effects of assembly errors that are unavoidable during manufacturing, thereby improving product yield.

() As mentioned in (), the depth of focus of the focusing lens can be made shallow by shortening the tube length, resulting in MS-type inherent noise (TV Society Technical Report).
vol. 5, No. 10, pp. 19-24).

[Brief explanation of drawings]

FIG. 1A is a sectional view showing the basic structure of the image pickup tube of the present invention, FIG. 1B is an enlarged view of its target section, FIG. 1C is an enlarged view of the electron gun section, and FIG. FIG. 2 is a developed diagram showing the pattern of the lectron, and FIG. 2 is a distribution diagram of equipotential lines showing the formation state of the collimation lens near the mesh in the present invention.
Fig. 3 is a characteristic curve diagram showing the relationship between l/d and optimal E _CM /E _CD , Fig. 4 is a characteristic curve diagram showing the relationship between l/d and figure distortion,
Characteristic curve diagrams showing the relationship between deflection voltage and resolution, Figures 5A to 5D are explanatory diagrams showing changes in the uniformity of the deflection electric field when the value of l/d is changed, and Figure 6 is an explanatory diagram, respectively. A characteristic curve diagram showing the change in resolution with respect to E _CM /E _CD , Fig. 7 is a distribution diagram showing the focused magnetic field distribution with respect to the distance from the outer surface of the face plate in the image pickup tube of the present invention, and Fig. 8 is a distribution diagram showing the magnetic field distribution with respect to l ^* / d ^* . Change B _zp ,
Characteristic curve diagrams showing changes in B _zpe , B _zpf and power consumption P _f , and FIGS. 9A and 9B show changes in the collimation lens when the length of the upper ring electrode in the present invention is changed, respectively. An explanatory diagram, FIG. 10 is a characteristic curve diagram showing changes in figure distortion and resolution with respect to the twist angle θ _e of the deflectron pattern,
FIG. 11 is a characteristic curve diagram showing changes in deflection voltage with respect to θ _e , and FIG. 12 is a characteristic curve diagram showing changes in figure distortion, resolution, and deflection voltage with respect to pitch l _p of the deflectron pattern. DESCRIPTION OF SYMBOLS 1... Electron gun part, 2... Holding body, 3... Glass outer tube, 4... Reflection plate electrode, 5... Deflectron electrode, 6... Lower ring electrode, 7... Upper ring electrode, 8... ...Target, 9...Mesh stand, 1
0...Mesh electrode, 11...Indium ring, 12...Intermediate glass cylinder, 13...Focusing electromagnetic coil, 14...Collimation lens, 15
... Stem, 16 ... Deflection center, 17 ... Face plate,
21...electron beam, 5A...center of deflectron, 8A...position of target, 18...position of beam restriction hole.

Claims (1)

[Scope of Claims] 1. A deflectron electrode divided into multiple parts arranged on the inner surface of the glass outer tube, an electron gun arranged at one end of the glass outer tube, a target arranged at the other end of the glass outer tube, It has a light-receiving face plate placed outside the target, a mesh electrode placed inside the target, and a focusing electromagnetic coil placed around the glass outer tube, the deflectron electrode and the mesh electrode In an image pickup tube that performs electromagnetic focusing and electric field deflection by having a focusing deflector that forms a collimation lens between An image pickup tube characterized in that d is set in a range of 2.0 to 3.5 to reduce the imaging magnification of the image pickup tube. 2. In the image pickup tube according to claim 1, the magnetic field distribution of the focusing electromagnetic coil is maximum at the center of the deflectron electrode, and at the end of the deflectron electrode on the target side or at the target surface. An image pickup tube characterized in that the magnetic field strength value is 0.2 or less of the maximum strength value mentioned above. 3. An image pickup tube according to claim 2, characterized in that the intensity value of the magnetic field in the beam restriction hole of the electron gun is set to 0.5 or less with respect to the above-mentioned maximum intensity value. 4. In the image pickup tube according to any one of claims 1 to 3, an upper ring electrode is disposed between the mesh electrode and the deflectron electrode on the inner surface of the glass outer tube. An image pickup tube characterized in that a ratio l ₂ /d of a distance l ₂ from an end of the upper ring electrode to the mesh electrode and a diameter d of the deflectron electrode is set in a range of 0.15 to 1.0. 5. In the image pickup tube according to any one of claims 1 to 4, the twist angle θ _e of the deflectron electrode is in the range of 45° to 135°, and the pitch of the deflectron electrode is in the range of 45° to 135°. An image pickup tube characterized in that a ratio l _p /d between l _p and a diameter d of the deflectron electrode is set in a range of 0.35 or less.