JPS63237337A - Cathode-ray tube - Google Patents

Abstract

PURPOSE:To obtain a focus state near a true circle with a simple structure by providing two four-electrode lenses. CONSTITUTION:An electron gun 1 is provided with unipotential type four- electrode lenses 13, 14 and a scan expanding lens 4 as a bipotential type four- electrode lens. The lens 13 acts as a convex lens in the vertical direction and as a concave lens in the horizontal direction, the lens acts as a thick convex lens in the vertical direction and as a thin concave lens in the horizontal direction respectively, the horizontal deflection beam is deflected and expanded in the lens 4, and the vertical deflection beam is reversed in its advance direction and deflected and expanded. The distance between an object point 49 and the lens 13 and the distance between the lenses 13, 14 are made nearly equal, and a focus state near a true circle is obtained on a screen 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cathode ray tube (CRT) having a scanning magnification (deflection magnification) lens.

[Prior Art] Three sets of quadrupole lenses are provided to make the image point (spot) on the CRT screen of an oscilloscope close to a perfect circle, and a scanning magnifying lens is provided near the rear acceleration electrode to further expand the deflection. , for example, JP-A-59-134
It is disclosed in Japanese Patent No. 531.

[Problem to be Solved by the Invention] When three quadrupole lenses are provided as described above, it is possible to obtain a good focus state in which the image point is close to a perfect circle, but CR
The configuration of T becomes complicated and the cost inevitably increases.

Therefore, an object of the present invention is to provide a CRT with a simple configuration.

[Means for Solving the Problems] A first invention of the present application for solving the above problems and achieving the above objects includes an electron beam generating means and an electron beam emitted from the electron beam generating means. a screen or target for projecting; and a screen or target arranged along the traveling path of the electron beam when not deflected, having a convex lens action in a first direction in a plane perpendicular to the traveling path, and perpendicular to the first direction. a unipotential type first quadrupole lens having a concave lens action in the second @ direction; a unipotential second quadrupole lens having a convex lens action in the direction; a deflection means for deflecting the electron beam in the first direction and the second direction; the deflection means and the screen or target; and has a convex lens effect in the first direction and a concave lens effect in the second direction, and deflects the electron beam by reversing the traveling direction of the electron beam deflected in the first direction. a bipotential scanning magnifying lens formed to magnify the electron beam; This relates to cathode ray tubes arranged in a perfect circle.

The second invention of the present application is one in which an axially symmetrical lens is added to the CRT of the first invention.

[Effect].

In the CRT of the above invention, two quadrupole lenses are provided instead of three quadrupole lenses. With only two quadrupole lenses, it is impossible to set the focus so that the beam spot approaches a perfect circle. Therefore, in the present invention, the focus lens system is formed by a combination of two unipotential quadrupole lenses and a scanning magnifying lens (bipotential quadrupole lens).

If the distance W from the object point (crossover) to the first quadrupole lens is approximately equal to the distance d from the first quadrupole lens to the second quadrupole lens, the configuration according to the present invention can achieve a focus state that is close to a perfect circle. can be obtained.

[Embodiment] Next, a CRT of an oscilloscope according to an embodiment of the present invention will be explained.
Explain. FIG. 1 shows a CRT in which an electronic mirror 1, a vertical deflection system 2, a horizontal deflection system 3, a scanning magnifying lens 4, a rear acceleration electrode 5, and a fluorescent screen 6 are housed in an exhaust pipe body 7.

The electron gun 1 includes a cathode 8 arranged along the tube axis 1a, a control electrode 9, an accelerating electrode 10, and first and second unipotential quadrupole lenses 13,14. The screen 6 is constructed by coating a face plate 17 with a fluorescent substance 18 and providing a conductive layer 19 thereon.

The first quadrupole lens 13 is made up of a combination of a first group of three plate electrodes 30 and a second group of three plate electrodes 31 each having a hole through which the electron beam passes. The three plate-shaped electrodes 30 of the first group are connected in common by a lead 32 and connected to a positive power supply terminal 26a via a variable resistor 25a.

The three plate-shaped electrodes 31 of the second group are connected in common by the lead 33, and the negative power terminal 2 is connected via the variable resistor 28a.
9a. - The second quadrupole lens 14 consists of a first group of three plate electrodes 34 and a second group of three plate electrodes 34 having holes through which the electron beam passes. The three plate electrodes 34 of the first group are commonly connected by a lead 36 and connected to the positive power terminal 26b via a variable resistor 25b, and the plate electrodes 35 of the second group are commonly connected by a lead 37. connected to variable resistor 28
b to the negative power supply terminal 29b. Note that the first and second groups of plate electrodes 34 and 35 are arranged alternately!
has been done.

The first group of plate-like electrodes 30 and the second group of plate-like electrodes 31 of the first quadrupole lens 13 have through holes 38 and 39 in the center of the discs, as shown in FIG. First group of plate electrodes 30
As is clear from FIG. 3, the through hole 38 has a first pair of circumferential edges 40.41 and a second pair of circumferential edges 42.43 facing each other about the tube axis. First pair periphery 40.41
is formed into a curve that approximately satisfies the equation x2-y2=b2 indicating a rectangular hyperbola. The second pair of peripheral edges 42, 43 do not have circles, but are formed into curved lines that substantially satisfy the equation x2+y2=a2. Note that the distance Wb from the center of the xy coordinates, that is, the tube axis to the apex of the first pair of peripheral edges 40 and 41, and the distance Wb from the center to the second
The relationship between the pair of peripheral edges 42 and 43 and the distance 1ia to the apex is a>>b, and for example, a=2b.

The second group of plate electrodes 31 shown in FIG. 2 corresponds to the first group of plate electrodes i30 rotated 90 degrees around the tube axis. Therefore, the peripheral edges 44, 45 of the first pair of plate-shaped electrodes 31 of the second group have a curve that does not show a rectangular hyperbola and substantially satisfies the formula x -y2=-b2, and the peripheral edge 46 of the second pair .47 has a curve that almost satisfies the equation +X2+y2=-a2 indicating a circle.

The first group of three plates! f! 30 are formed identically,
The three plate-shaped electrodes 31 of the second group are also formed in the same manner.

The three first group plate electrodes 34 of the second quadrupole lens 14
are formed in the same or similar pattern to the plate electrodes 31 of the second group of the first quadrupole lens 13, and the three plate electrodes 35 of the second group are formed in the same pattern as the plate electrodes 31 of the second group of the first quadrupole lens 13. They are formed in the same or similar pattern to the plate-like electrodes 30 of the first group.

The second quadrupole lens 14 is arranged between a vertical deflection system 2 consisting of a pair of deflection plates and a horizontal deflection system 3 consisting of a pair of deflection plates.

A scanning magnifying lens 4 disposed between the horizontal deflection system 3 and the screen 6 connects the first cylindrical electrode 15 and the second cylindrical electrode 16 to a pair, as shown in FIGS. 4 to 7. This is a bipotential type quadrupole lens consisting of a laminated lens, and is the same as that disclosed in Japanese Patent Application No. 88732/1988 filed by the applicant of the present invention.

The first cylindrical pole 15 of this scanning magnifying lens 4 has a first pair of surfaces 62.63 each having a tongue 60.61 and a second pair of surfaces 66 each having a recess 64.65. ．．
67 and is connected to ground. Second cylindrical electric f! 16 consists of a first pair of surfaces 68, 69 and a second pair of surfaces 70, 71, surrounds the end of the first cylindrical electrode 15 on the screen side, and is a post-acceleration type w! 5.

In addition, each side 62.63.66.67.68.69.70
．． 71 is recessed in the tube axis direction in the shape of a hyperbola or a quadratic curve approximated thereto.

The vertical focus state of the CRT including the scanning magnifying lens 4 is shown in FIG. 8(A), and the horizontal focus state is shown in FIG. 8(B).
), the first quadrupole lens 13 acts as a convex lens in the vertical direction and a concave lens in the horizontal direction, the fourth quadrupole lens 14 acts as a concave lens in the vertical direction and a convex lens in the horizontal direction, and the scanning magnifying lens 4 It acts as a thick convex lens in the vertical direction and as a thin concave lens in the horizontal direction.

Object point 49 is the crossover of electron beam 57 emitted from cathode 8 in FIG. The distance between this object point 49 and the first quadrupole lens 13 is W, the first quadrupole lens 1
3 and the second quadrupole lens 14 is d, and the distance between the convex lens Q1 of the scanning magnifying lens 4 and the second quadrupole lens 14 is shown by two convex lenses Q1, Q2 and one concave lens Q3.
The distance between the concave lens Q3 and the second quadrupole lens 14 is ql.
The distance between the convex lenses Q1 and Q2 is H1, the distance from the convex lens Q2 to the screen 6 is Pl, and the distance from the concave lens Q3 to the screen 6 is Pl.

In the vertical direction, the beam 5 as shown in FIG. 8(A)
7a is converged at the object point 49, then diverges, is converged by the first quadrupole lens 13, becomes a nearly parallel beam under the concave lens action of the second quadrupole lens 14, and is converged within the scanning magnifying lens 4. After that, it becomes a divergent form again,
The light is projected onto the screen 6 under the convergence effect of the convex lens Q2.

In the horizontal direction, the beam 57b emitted from the object point 49 in a diverging form is subjected to a concave lens action by the first VE pole lens 13, a convex lens action by the second quadrupole lens 14, and a concave lens action by the scanning magnifying lens 4. is received and projected onto the screen 6.

This CRT has one less quadrupole lens than the conventional one that includes three quadrupole lenses, but it has two quadrupole lenses.
3. It is not possible to obtain a perfect circular image just by changing the voltage in step 14. Since the voltage of the scanning magnifying lens 4 is fixed,
The constants of lenses Q1 to Q3 cannot be changed by voltage.

Therefore, in the present invention, the first and second quadrupole lenses 13.
14, that is, the distances w and d, are aligned to obtain a perfect circular image. A perfect circular image can be obtained by setting the distances W and d approximately equal. This will be explained using a formula.

The conditions for obtaining a perfect circular image on the screen 6 by fixing d and ql are given by: From the combination principle of the scanning magnifying lens 4, Ql
, Q2, and Q3 are each S3, S4, and S5.
Then, α, β, γ α=q PS − (q + P) (2) β
=(12Pl 35 + (q2 +P2)...
It is given by (3). However, when calculated by giving each constant from equation (1), W:td is obtained.

If the voltage of the control voltage [, 9 in the CTR shown in FIG. However, when the voltage of the control electrode 9 is kept substantially constant and the CTR is operated at a constant brightness, or when the object point 49 is obtained by the aperture object point method, the distance W shown in FIG. 8 must be kept constant. Can be done. Therefore, even though the CRT has a simple structure in which the number of quadrupole lenses is reduced by one, a good focus state can be obtained.

Equipotential lines 80 and 81 shown by broken lines in FIGS. 6 and 7 are generated inside the scanning magnifying lens 4, so the beam 82 deflected in the horizontal direction is deflected and expanded as shown in FIG.
As shown in FIG. 13, the vertically deflected beam 83 has its traveling direction reversed and is deflected and expanded.

[Another Embodiment] Next, a CRT according to another embodiment of the present invention shown in FIGS. 9 and 10 will be described. However, in FIG. 9, parts common to those in FIG. 1 are given the same reference numerals and their explanations will be omitted. This CRT includes an accelerating electrode 10 and a first quadrupole lens 13.
A unipotential type axisymmetric lens 11 is provided between the two. The axially symmetrical lens 11 includes three plate electrodes 11 having circular holes 91, 92, and 93 formed in alignment with the tube axis 1a.
Consisting of a, 11b, 11C, plate-shaped electrodes 1ila on both sides,
IIC is connected to the accelerating electrode 10, and the central plate electrode 11
b is connected to a power supply terminal 21 via a variable resistor 20. A voltage lower than that applied to the accelerating electrode 10 is normally applied to the plate-shaped pole 11b, and this axially symmetrical lens 11 exhibits a convex lens effect.

If the convex lens action of the axially symmetrical lens 11 is controlled to compensate for crossover, that is, movement of the object point 49 due to changes in the voltage of the control electrode 9, it is possible to maintain a good focus state despite changes in the control voltage. can.

[Modifications] The present invention is not limited to the above-described embodiments, and the following modifications are possible, for example.

(1) The second quadrupole lens 14 may be placed before the vertical deflection system 2.

(2) The scanning magnifying lens 4 is made of Japanese Patent Application Laid-Open No. 60-65436,
JP-A-60-23939, JP-A-59-189539,
JP-A-53-129577, JP-A-59-134531
No. Publication, Japanese Patent Application No. 61-88732, Japanese Patent Application No. 61-887
33, as disclosed in U.S. Pat. No. 4,302,704.

(3) The present invention is not limited to the CRT of an oscilloscope, but can be applied to other electron guns such as display tubes and storage tubes.

(4) An aberration correction electrode may be added after the acceleration electrode 10.

(C) The first and second quadrupole lenses 13 and 14 are
As shown in FIG. 1, it may be configured by a combination of four electrodes 53, 54, 55, 56.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a CRT with a good focus state despite having a simple ridged structure.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway view of a CRT according to an embodiment of the present invention, Fig. 2 is a perspective view showing a plate-shaped electrode of a quadrupole lens in the CRT of Fig. 1, and Fig. 3 is a plate-shaped electrode. 4 is a perspective view showing the scanning magnifying lens, FIG. 5 is a perspective view showing the first cylindrical electrode in FIG. 4, and FIG. 6 is a cross-sectional view of the scanning magnifying lens in FIG. 4. , FIG. 7 is a vertical cross-sectional view of the scanning magnifying lens shown in FIG. 4, FIG. 8 is a diagram showing vertical focus and horizontal focus in optical detail, and FIG. 9 shows a CRT according to another embodiment of the present invention. 10 is a perspective view showing an axially symmetrical lens of the CRT shown in FIG. 9, and FIG. 11 is a front view showing a modification of the quadrupole lens. DESCRIPTION OF SYMBOLS 1...Electron gun, 4...Scan magnifying lens, 8...Cathode, 9...Control electrode, 10...Acceleration electrode, 11...
・Axisymmetric lens, 13... Second quadrupole lens, 14・
...Third quadrupole lens.

Claims (1)

[Scope of Claims] [1] An electron beam generating means; a screen or target on which the electron beam emitted from the electron beam generating means is projected; and a screen or target disposed along the traveling path of the electric beam when not deflected; a unipotential first quadrupole lens having a convex lens action in a first direction in a plane perpendicular to the traveling path and a concave lens action in a second direction perpendicular to the first direction; a second unipotential quadrupole lens disposed on the exit side of the quadrupole lens, having a concave lens action in the first direction and a convex lens action in the second direction; and a deflecting means for deflecting the deflection in the direction of and the second direction, the deflection means being disposed between the deflection means and the screen or the target, having a convex lens action in the first direction, and having a convex lens action in the second direction. a bipotential scanning magnifying lens having a concave lens effect and formed to reverse the traveling direction of the electron beam deflected in the first direction and expand the deflection; A cathode ray tube, characterized in that the quadrupole lens and the scanning magnifying lens are arranged so that the spot of the electron beam on the screen or target becomes a perfect circle or a nearly perfect circle. [2] A claim in which the deflection means comprises a first deflection system that deflects the electron beam in the first direction, and a second deflection system that deflects the electron beam in the second direction. The cathode ray tube according to item 1. [3] A cathode, a screen or target for projecting the electron beam emitted from the cathode, and a control arranged along the traveling path of the electron beam from the cathode to the screen or target when not deflected. an electrode, an accelerating electrode disposed on the emission side of the control electrode, an axially symmetrical lens disposed on the emission side of the accelerating electrode, and a plane disposed on the emission side of the axially symmetrical lens and perpendicular to the traveling path. has a convex lens effect in the first direction,
a unipotential first quadrupole lens having a concave lens action in a second direction perpendicular to the first direction; and a unipotential first quadrupole lens disposed on the exit side of the first quadrupole lens and having a concave lens action in the first direction. a unipotential second quadrupole lens having a convex lens action in the second direction; a deflection means for deflecting the electron beam in the first direction and the second direction; disposed between the means and the screen or target, having a convex lens effect in the first direction and a concave lens effect in the second direction, and traveling of the electron beam deflected in the first direction; a bipotential scanning magnifying lens formed to deflect and magnify the electron beam by reversing the direction; A cathode ray characterized in that the spot is arranged to be a perfect circle or a nearly perfect circle, and the cathode ray is configured such that the axisymmetric lens corrects a focus shift due to a change in crossover due to a change in the voltage of the control electrode. tube.