JPS6337545A - Cathode-ray tube - Google Patents

Abstract

PURPOSE:To prevent deflecting characteristics (aberration and landing errors) from deteriorating, by installing both first and second cylindrical electrodes installed in order from the electron gun side along a pass of electron beams, and specifying each axial length of these electrodes. CONSTITUTION:An electrode G4 is a focusing electrode forming an electrostatic focusing lens as well as a deflecting electrode in type, and it forms such an electrostatic lens that makes the electron beam deflected together with an electrode G5 land on a photo-conductive film surface almost vertically. Since intensity of a collamation lens when the electron beam is deflected and a position where deflection is started are correspondent to 1:1, relation between an electrode inside diameter and length of the deflecting electrode and relation between these electrodes G4 and G5 in length both are primarily determined, and in both first and second electrodes G4 and G5, axial length of the first electrode 4 is set to 0.81-1.26 times over this first electrode diameter, and axial length of the second electrode G5 to 0.11-0.21 times over the axial length of the first electrode G4, respectively. With this constitution, there is no landing error and, what is more, such a cameral tube that is small in aberration is securable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cathode ray tube suitable for application to an electrostatic focusing/electrostatic deflection type image pickup tube.

[Conventional technology]

Conventionally, known electrostatic focusing/electrostatic deflection type image pickup tubes are disclosed in JP-A-60-240032 and JP-A-60-4735.
As disclosed in Publication No. 1, there are types shown in FIGS. 1 and 3. Common parts between FIG. 1 and FIG. 3 are given the same reference numerals.

In FIG. 3, 1 is a glass bulb, 2 is a face plate, and 3 is a photoconductive film surface (target surface).

5 is an indium ring. Reference numeral 4 denotes a signal extraction electrode which penetrates the face plate 2 and comes into contact with the photoconductive film surface 3. K.

Gs and G2 are a cathode, a first grid electrode, and a second grid electrode, respectively, which constitute an electron gun, and K + G
1 t G 2 constitutes an electron gun section which is an electron beam generating section. In the electron gun of the diode gun, there is no G1 electrode, and an electron beam is emitted from the cathode K due to the positive voltage of the G2 electrode. Further, BD is a beam limiting aperture above G2'W1. G3゜G4. G5 and Go are the 3rd. 4th. After metals such as chromium and aluminum are vapor-deposited or plated on the inner wall of the glass bulb 1 using the fifth grid electrode and the sixth grid electrode, they are formed into a predetermined pattern by, for example, laser cutting or photo-etching. A developed view of these electrodes is shown in FIG. G4 electrode is, for example, four electrodes H+/H
It has a curved arrow pattern in which -, V+, and - are arranged alternately. G8 is a mesh-like sixth grid electrode, to which a predetermined voltage is applied via the indium ring 5.

The electrodes Gs, Ga, and Ga form an electrostatic focusing lens, and G4 also serves as a deflection electrode. Further, an electrostatic lens (collimation lens) is formed to allow the electron beam deflected by the electrode G6 to land substantially perpendicularly to the photoconductive film surface.

The type shown in FIG. 1 has one less electrode than the type shown in FIG. 3, and G5 is a mesh-like fifth grid electrode. A predetermined voltage is applied to this electrode G+s via an indium ring 5. A developed view of the electrode is shown in FIG.

The electrodes Ga and Ga form an electrostatic focusing lens, and the electrode G4 also serves as a deflection electrode.

In the example of FIG. 3, in order to apply a predetermined voltage to the electrode tiiGδ, a hole is made in the glass bulb corresponding to the electrode Gδ as shown in 6, as disclosed in Japanese Patent Application Laid-Open No. 60-47351. Pins are soldered or conductive frits are provided, and the voltage is applied through these metal pins or conductive frits. Alternatively, a ceramic ring with a frit seal and a conductive portion formed on one surface is connected to the end of the glass bulb, and the voltage is applied through this ceramic ring. Conventionally, in these methods, maintaining airtightness has been a problem. In addition, the work is complicated, the manufacturability is poor, and there are problems in terms of strength. Furthermore, it is necessary to supply voltage to the electrode G5 from the side of the tube wall, which has the disadvantage of complicating the structure of the image pickup tube assembly.

On the other hand, the type shown in FIG. 1 has a structure in which the electrode Ga is eliminated from the type shown in FIG. 3, and the above problem is solved.

[Problem that the invention seeks to solve]

However, unlike the type shown in Fig. 3, the type shown in Fig. 1 has the disadvantage that the deflection characteristics (aberration, landing error) are significantly degraded because the deflection electrode forms part of the collimation lens. Ta.

The object of the invention is to provide a structural dimension of the type shown in FIG. 1 which eliminates the above-mentioned disadvantages.

[Means for solving problems]

The above purpose is to set the axial length of the first electrode G4 which deflects the electron beam among the first and second electrodes G4 and Gs to be 0.81 to 1.26 times the inner diameter of the first electrode, and This is achieved by making the axial length of the two electrodes G11 0.11 to 0.21 times the axial length of the first electrode G4.

[Effect]

In the type shown in FIG. 1, electrode 04 is a focusing electrode forming an electrostatic focusing lens and deflection 11! It is also extreme. Moreover, an electrostatic lens (collimation lens) is formed together with the electrode G8 to cause the deflected electron beam to land almost vertically on the photoconductive film surface. There is a one-to-one correspondence between the strength of the collimation lens when deflecting the electron beam and the position where the deflection starts, so the amount of deflection (scan size) corresponds to the inner diameter of the electrode, so the inner diameter of the electrode and the deflection electrode The relationship between the length of the electrode G4 and the length of the electrode G4 and the electrode GIs forming the collimation lens are uniquely determined.

Therefore, by optimizing the lengths of the electrode G4 and the electrode G3 of the type shown in FIG. 1, it is possible to obtain a simple imaging tube with no landing error and small aberrations.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. Fifth
The figure is a model of the type of electrode shown in Figure 1.0 Normally in a 1# tube, the inner diameter φ of electrode G4 is approximately 24 mm.
In the case of a diode gun electron gun, the operating voltage is 20V at the electrode G2.

The voltage of electrode G8 is 800 mm, the DC focusing voltage and deflection voltage are applied to electrode G4, and the voltage of electrode G5 is 50 mm.
It is v. Further, a voltage of 50 μm is applied to the surface of the photoconductive film. Also, the length 12as of the electrode G3 is nas/φ=1.25
In Fig. 5, the length ΩG4 of the electrode Ga and the electrode G
FIG. 6 shows the landing characteristics when the electron beam is deflected diagonally to the screen when the IS length Qaa is used as a parameter.

Qca and ΩG8 are normalized by the inner diameter φ of the electrode G4. The longer ΩG4 is, the more fia+s is required in order to make the landing of the electron beam (to make the incident angle of the electron beam on the electrode GI5 zero). It turns out that it is necessary to make it longer.

Figure 7 shows the length ΩG4 of the electrode G4 and the deflection of the electron beam diagonally to the screen when Qca is adjusted and the electron beam is landed each time (the angle of incidence of the electron beam on the electrode Gs is zero). For example, in a 1# tube, it is desirable that the aberration is 20 μm or less.
It can be seen that in order to satisfy this condition Qa with the electron beam landing, it is necessary to set the length ΩG4 of the electrode G4 to □=0.81 to φ 1.26. Further, the incident angle of the electron beam on the electrode 66 is permissible from 12" to 2°. In FIG. 8, the incident angle on the electrode G6 is 12" and 0.
From figure 0, which shows the relationship between ΩG4 and Q05/Qa4 in the case of
In order to keep the beam incidence angle to a constant value, ΩG4 and Q
It can be seen that it is sufficient to keep the ratio to aa at a substantially constant value. It can be seen that the condition for beam landing (beam incident angle 0° to electrode G5) is that Q a11/ΩG4 must be approximately 0.15. Also, from the above tolerance range, Qo
It is desirable to set a/Q04 between 0.11 and 0.21.

Further, FIG. 9 shows the landing characteristics of the electron beam when the length llog of the electrode G3 is changed.

At this time, 12a4/φ= 1, 19, QaII
/Qca=0.18. It can be seen from the figure that the beam landing characteristics hardly change depending on Qas.

Therefore, it is desirable to set ΩG3 to an appropriate value based on the magnitude of the aberration.

By the way, QOa and flar+ have been optimized (Qaa
/φ =1.1 9. ucs/uca=0.1 8
．． Table 1 compares the characteristics of the type shown in FIG. 1 and the conventional type shown in FIG. 3 when nos/φ is 1.25.

Table 1 As shown here, by optimizing ΩG4 and flGIs, it is possible to eliminate landing errors and reduce aberrations, and furthermore, it is possible to make the image magnification much smaller than the type shown in Figure 3. An excellent imaging tube can be obtained.

〔Effect of the invention〕

As mentioned above, in the type shown in Figure 1, the electrode G
By specifying the length ΩG4 of the electrode G4 and the length ΩGIIt of the electrode G6 to the optimum length, it is possible to obtain an image pickup tube that is free from landing errors and has small aberrations. Furthermore, since the structure is simpler than the conventional type shown in FIG. 3 (the number of electrodes is one less), there is no need to supply voltage to the electrodes from the side of the tube wall.

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams showing characteristics of an image pickup tube to which the present invention is applied, and FIGS. 7, 8, and 9 are diagrams showing characteristics of an image pickup tube to which the present invention is applied. 1...Glass bulb, 2...Face plate, 3
...Photoconductive film surface (target surface), ΩG8...Length of electrode Gδ, ΩG4...Length of electrode G4, Qo+s・
...Electronic connection to electrode G6 3 Figure G6 6 Figure 7 Figure 44/p Figure 3 Noro t/f

Claims (1)

[Claims] 1. The first and second cylindrical electrodes are provided in order from the electron gun side along the electron beam path, the first electrode is a deflection electrode for deflecting the electron beam, and the first electrode is a deflection electrode that deflects the electron beam; The axial length of the first electrode is 0 of the inner diameter of the first electrode.
．． The range is from 81 times to 1.26 times, and the axial length of the second electrode is 0 times the axial length of the first electrode.
．． A cathode ray tube characterized by a magnification of 11 times to 0.21 times.