JPH053000A - Traveling wave type deflection device - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the influence of reflection in a traveling wave deflector and improve waveform distortion. Structure: Ground conductors 25 and 28 are arranged inside insulating substrates 23 and 26 extending in the beam direction (Z-axis direction).
Spiral conductors 24, 27 are provided on the outer periphery of the insulating bases 23, 26.
To place. The ground conductors 25 and 28 are provided so that the characteristic impedance is substantially uniform in the direction along the spiral conductor, that is, in the traveling wave transmission direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling wave type deflection device for a cathode ray tube.

[0002]

2. Description of the Related Art If the deflection voltage does not change while the electron beam passes through a deflecting device, it is possible to obtain the deflection of the electron beam in proportion to the magnitude of the deflection voltage. However, if the deflection voltage changes while the electron beam passes through the deflector due to the high frequency of the deflection voltage, the desired deflection becomes impossible. In order to solve this problem, DC to several hundred MHz
In the CRT for observing the signal of, the traveling wave type deflection device is used. In the traveling wave type deflecting device, the traveling speed of the deflection signal propagating from one end to the other end of the traveling wave type deflection conductor (traveling wave transmission line) such as a spiral is made to substantially coincide with the traveling speed of the electron beam. As a result, the deflection action time becomes long, the electron beam can be sufficiently deflected, and it becomes possible to provide a wide-band deflection device.

In order to easily and firmly form such a traveling wave type deflector, a strip-shaped conductor is spirally wound around a long insulating base body, and a ground plate is inserted in the inside, and the ground plate is used in the Z-axis direction. On the other hand, a structure having a uniform characteristic impedance is disclosed in Japanese Patent Publication No. 57-10539.
In addition, a band-shaped conductor is coaxially formed on the ground plate via an insulating support substrate, and a traveling wave transmission line (delayed between the spiral conductor of the single deflector excluding the deflection capacitance between the deflectors and the ground plate is provided. Japanese Patent Publication No. 58-14021 discloses that the characteristic impedance of a wave circuit) is made uniform along the spiral conductor. Further, by inserting a ground plate inside the dielectric, winding a strip-shaped conductor around the dielectric, and changing the value of the dielectric constant of the dielectric or the width of the strip-shaped conductor, the characteristic impedance of the deflector beam surface and the back surface is made uniform. An attempt to achieve this is disclosed in JP-A-63-155539.

[0004]

By the way, in the conventional device, the uniformity of the characteristic impedance is considered only in the beam direction (Z direction), and the direction along the spiral conductor (deflection signal propagation direction) is taken into consideration. It has not been. Even if it is partially considered, it is not considered for the entire deflecting body including the deflection capacitance. Compensation for the difference in characteristic impedance between the spiral conductors on the beam facing surface and the back surface (beam non-facing surface) is performed by changing the value of the dielectric constant of the dielectric inside the spiral conductor, or on the strip conductor. Compensation is done by changing the width. It is difficult to arbitrarily specify the value of the dielectric constant of the dielectric. Further, changing the width of the strip conductor is difficult to perform without sacrificing the deflection sensitivity and the high frequency characteristics. In any case, the traveling wave transmission line is treated as a traveling transmission line in the Z direction, and is not considered as a traveling wave transmission line in the direction along the spiral conductor.
Except for the Z direction, the lumped constant per turn is considered equivalent. This means that the effect of reflection due to non-uniformity of the characteristic impedance of the traveling wave transmission line in the direction along the spiral conductor is not taken into consideration. It is said that the lumped-constant theory is almost valid only when the length of the part that can be represented by the lumped constant is up to about 1/10 of the wavelength, and at frequencies higher than that, it is necessary to handle it with a transmission line. There is. Here, the length per turn is 1
If it is 9.0 mm, the frequency that can be handled by the lumped constant theory is up to about 1.57 GHz. The normal deflection system band is CR
Since a band about 3 to 3.5 times the band used by T is required, if the band used by the CRT is up to 450 MHz, it can be handled by lumped constants except in the Z direction. Up to this band, even if the characteristic impedance in the direction along the spiral conductor is not uniform, there is no problem if the characteristic impedance is uniform in the Z direction. For the band higher than this, there is a problem in the uniformity of the characteristic impedance in the direction along the spiral conductor (traveling wave transmission line). From the transmission line analysis, it is clear that if there is a mismatched part in the characteristic impedance, it is reflected at that part, and the higher the frequency, the greater the amount of reflection. If the mismatch is periodic, the influence of reflection becomes larger. Therefore, reflection occurs from the characteristic impedance mismatching part of the traveling wave transmission line, the reflected wave is transmitted to the sending end, re-reflected at the entrance of the amplifier and superimposed on the incident wave, and ideal deflection becomes impossible and waveform distortion occurs. Will occur. This limits the usable band of the traveling wave transmission line. In particular, when the impedance on the transmission end side of the amplifier cannot be matched, waveform distortion occurs even with a reflection amount of several percent, which is a problem as a product.

Therefore, an object of the present invention is to easily make the characteristic impedance in the direction along the spiral conductor uniform, and to reduce the reflection amount due to the nonuniformity of the characteristic impedance in the direction along the spiral conductor. The present invention provides a traveling wave deflecting device having a wide band.

[0006]

The present invention for achieving the above object comprises a first and a second deflecting body which are arranged so as to face each other across an electron beam passage, and the first deflecting body is a first deflecting body. One spiral conductor and a first ground conductor arranged inside the first spiral conductor, wherein the second deflector has a second spiral conductor and the second spiral conductor. In a traveling wave type deflection device including a second ground conductor arranged inside a circular conductor, the characteristic impedances in the directions along the first and second spiral conductors are made substantially uniform. The present invention relates to a traveling wave type deflection device in which the first and second ground conductors are provided.

[0007]

According to the present invention, the influence of reflection can be reduced and the waveform distortion can be improved by making the characteristic impedance substantially uniform in the direction along the spiral conductor, that is, in the deflection signal propagation direction that coincides with the spiral direction. .. This allows the traveling wave deflecting device to have a wider band.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a CRT of an oscilloscope according to an embodiment of the present invention will be described with reference to FIGS. This C
As shown in FIG. 7, the RT is composed of an evacuated tube body 2, a cathode ray tube electrode assembly 3 incorporated therein, and a fluorescent screen 4. The cathode ray tube electrode assembly 3 includes an electron gun 7 including an assembly 5 of a cathode and a control grid and an anode 6, a first quadrupole lens 8, a second quadrupole lens 9, a vertical deflection device 10 according to the present invention, and a first quadrupole lens 10. Three quadrupole lens 11,
A horizontal deflection device 12 and a deflection magnifying electron lens 13 are provided, which are supported by common insulating supports 14 and 15. The fluorescent screen is a face plate 16,
It is composed of a fluorescent material layer 17 and a conductor layer 18. Conductor layer 18
Is connected to a post-stage acceleration electrode 19 extending to the vicinity of the deflection magnifying lens 13.

The vertical deflection apparatus 10 according to the present invention has a beam path 20 as can be seen from FIGS. 1, 2 and 7.
First and second deflecting bodies 21, 2 arranged so as to sandwich
Equipped with 2. The first deflector 21 includes a first insulating base 23, a first spiral conductor 24, and a first ground conductor 25, and is arranged so as to extend in the beam traveling direction (Z-axis direction). Similarly, the second deflector 22 also includes a second insulating base 26, a second spiral conductor 27, and a second ground conductor 28, and is arranged so as to extend in the beam traveling direction (Z-axis direction). ing.

The first and second insulative substrates 23 and 26 have a pair of legs 23a and 26a on the beam entrance side and leg portions 23b and 26b on the beam exit side, respectively. The legs 23a, 23b, 26a, 26b are joined together by abutting. Of course, leg 2
3a, 23b, 26a and 26b are formed so as not to obstruct the passage of the beam. Further, the grooves 29, 3 extending in the longitudinal direction are formed in the first and second insulating bases 23, 26.
0 is formed, ground conductors 25 and 28 are arranged therein, and the first and second spiral conductors are provided on the outer periphery of the first and second insulating bases 23 and 26 so as to surround the ground conductors 25 and 28. 24 and 27 are wound.

The ground conductors 25 and 28 are fixed to the beam entrance end faces and the exit end faces of the first and second insulating substrates 23 and 26 by fixing members 31 and 32. Further, the ground conductors 25 and 28 are bent end portions 25a, 25b and 28.
a, 28b, functioning as support legs for the first and second deflectors 21, 22 and attached to the insulating supports 14, 15 of FIG. A preferred specific example of the mutual gap (gap) between the spiral conductors 24 and 27 on the beam facing surface is 0.9 mm.

In this embodiment, the first and second deflectors 21, 22 are arranged in parallel as shown in FIGS.
The mutual intervals are uniform with respect to the beam traveling direction. Even if the deflecting bodies 21 and 22 are arranged in parallel in this way, the CRT includes a quadrupole lens, and the beam passes between the pair of deflecting bodies 21 and 22 while being narrowed in the Y direction.
Even if the beam is deflected by 22, the deflectors 21, 22
Reach the screen without being cut by. Of course,
It is also possible to arrange the pair of deflecting bodies 21 and 22 so that the mutual spacing gradually widens toward the screen, or to start spreading from the middle of the pair of deflecting bodies 21 and 22 (for example, 1/2). is there.

The spiral conductors 24 and 27 of the first and second deflectors 21 and 22 are formed by winding a strip-shaped metal plate having a width of 1.6 mm around the first and second insulating substrates 23 and 26. .. As shown in FIG. 7, the input ends of the spiral conductors 24 and 27 are connected to the neck pin 33 via the input conductors 32a and 32b.
a, 33b, the output end of which is connected to the output conductor 34a,
It is connected to the neck pins 35a and 35b via 34b. In order to easily and accurately form the first and second spiral conductors 24 and 27, as shown in FIG. 4, grooves are formed on the pair of side surfaces of the first and second insulating bases 23 and 26. Three
1 is provided to keep the intervals and shapes of the adjacent strip-shaped conductors constant along the length direction of the deflecting body. In the preferred embodiment, the pitch of the spiral conductors 24, 27 is 2.38 mm,
The cross-sectional shape is a rectangular shape with a width of 6 mm and a height of 3.5 mm,
It is wound so as to be spiral in the Z direction.

First and second ground conductors 2 according to the invention
Reference numerals 5 and 28 are made of strip-shaped metal plates having a strength capable of supporting the first and second insulating bases 23 and 26 and the first and second spiral conductors 24 and 27. Z-axis direction) is arranged in the grooves 29, 30 provided in the first and second insulating bases 23, 26, and the spiral conductor 24 on the back surface is arranged as shown in FIGS. 2 and 3. 27
It is placed close to. In the preferred embodiment, as shown in FIG. 5, the ground conductors 25, 28 are made of a strip-shaped metal having a thickness of 0.5 mm and have a width of 2 mm and are narrowed at the ends (beam entrance side and exit side). ing. By narrowing at the ends, the characteristics of the inductance and capacitance at the ends of the traveling wave transmission line are compensated. Then, the spiral conductors 24, 27 from the rear surface side (the surface not facing the beam) to 0.
They are arranged at a distance of about 4 mm, and the characteristic impedance in the terminal direction is substantially uniform at each point in the direction along the spiral conductor (traveling wave transmission direction or conductor winding direction) including the deflection capacitance. That is, by adjusting the shapes and positions of the ground conductors 25 and 28, the characteristic impedances of the spiral conductors 24 and 27 on the beam facing surface side and the characteristic impedance on the beam non-facing surface side are made substantially equal to each other, and the characteristic impedances at all points in the traveling wave transmission direction are set. The characteristic impedances are made almost equal. Therefore, it becomes possible to maintain a desired characteristic impedance over the entire traveling wave transmission line. Figure 1
Reference numeral 0 specifically indicates the size and position of the cross section of the ground conductor 25. Now, the distance from the upper surface of the ground conductor 25 to the spiral conductor 24 is y ₁ , the distance from the lower surface of the spiral conductor 24 to the central lower surface of the insulating base 23 is y ₂ , the central lower surface of the insulating base 23. From the spiral conductor 24 facing the beam
To y ₃ , the distance from both side surfaces of the spiral conductor 25 to the spiral conductor 24 is x ₁ , the relative permittivity of the insulating substrate 23 is ε, and the spiral conductors 24 and 27 face each other in the beam passage. If the interval is d, then y ₁ = {(εy ₃ + y ₂ ) d} / {εd + 2 (εy ₃ +
y ₂ )} x ₁ = εy ₁ If the position and cross section of the ground conductor 25 are determined so that they satisfy the characteristic impedance at all points.
You can equalize the dance. The ground conductor 28 of the second deflector 22 has the same structure.

As shown in FIG. 8, since a balanced signal (a positive phase signal and its negative phase signal) is input to the first and second deflectors 21 and 22, the first and second deflectors are input. 21, 22
A virtual ground 36 is formed at the center of the gap. The traveling wave transmission line according to the present invention includes first and second spiral conductors 24 and 27, a virtual ground 36, and first and second spiral conductors arranged inside the first and second spiral conductors 24 and 27, respectively. Of ground conductors 25, 28. As the capacitance related to the spiral conductors 24, 27 at an arbitrary distance s along the spiral conductors 24, 27 from the starting ends of the spiral conductors 24, 27, the spiral conductors 24, 27 and the ground conductor 2
There is a capacitance Cg (s) between 5 and 28 and a capacitance (deflection capacitance) Cd (s) between the spiral conductors of the virtual ground 36. The characteristic impedance Z (s) at the distance s along the spiral conductors 24 and 27 can be expressed by the following equations, respectively, if the inductance L (s) at the distance s between the spiral conductors 24 and 27 is represented.

[0016]

[Equation 1]

Here, Cg (s) and Cd (s) include capacitance between adjacent conductors (coils) in the spiral conductors 24 and 27. Further, the insulating substrate 2 is added to Cg (s).
The influence of the relative permittivity values of 3 and 26 is included. C
d (s) is large when the spiral conductors 24 and 27 face the beam surface, and becomes substantially zero when the spiral conductors 24 and 27 come to the back surface. Here, the ground conductors 25, 2 are arranged so that Cg (s) becomes constant.
Consider the case where 8 is arranged. In this case, Cg (s)
Is a constant value C irrespective of the distance s between the spiral conductors 24 and 27.
It can be expressed as g. Further, the portion of Cd (s) facing the beam surface is set to a constant value Cd, and the other portions are set to zero. Since the inductance L (s) is considered to be almost constant, if L (s) = L, the characteristic impedance Z
(S) changes periodically between Z1 and Z2 as shown in FIG. Here, Z1 and Z2 can be expressed by the following equations.

[0018]

[Equation 2]

At this time, the characteristic impedance ZinN viewed from the entrance of the N-turn traveling wave deflection system can be treated and obtained as a composite line in which the transmission lines of Z1 and Z2 are connected in cascade. In FIG. 9, which shows a graph of the characteristic impedance along the spiral conductors 24, 27, the distance s is shown with reference to the output part and the number of turns is shown instead of the distance, for the sake of simplifying the analysis of the transmission line. There is. A1 to AN represent the beam facing surface portion, the characteristic impedance of this portion is Z2, and the width (distance) of this portion is 12. B
1 to BN-1 represent parts other than A1 to AN, the characteristic impedance of this part is Z1, and the width (distance) of this part is l1. C1 represents the end part from the exit of the beam facing surface of the right end turn to the terminating resistance, the characteristic impedance of this part is Z1, and the width (distance) of this part
Is l0. C2 represents the part from the entrance of the beam facing surface of the leftmost (final) turn to the amplifier, the characteristic impedance of this part is Z1, and the width (distance) of this part is l3. FIG. 9 shows characteristic impedances Zi1 to Zi2N as viewed from the respective positions at the terminal end. Zi1 is a characteristic impedance as seen from the exit of the beam facing surface for one turn and looking at the terminal end. The value of the characteristic impedance of the portion C1 and the terminating resistor R are matched. Zi2 is the characteristic impedance of the one-turn beam facing surface viewed from the entrance to the end. Zi3 is a characteristic impedance as seen from the exit of the beam facing surface of the second turn to the terminal end. Zi4 is 2
It is the characteristic impedance when the terminal end is seen from the entrance of the beam facing surface at the turn. Similarly, the N-1th turn,
The characteristic impedance of the Nth turn is shown.

From the transmission line analysis, the spiral conductors 24, 27
The characteristic impedance of can be expressed by the following equation.

[0021]

[Equation 3]

Since one turn is divided into two characteristic impedances Z1 and Z2 for analysis, N = 2 m. The value of the terminating resistor R is the same as the value of the characteristic impedance Z1. This formula is derived from the following recurrence formula.

[0023]

[Equation 4]

ZinN is a function of frequency according to equations (1) and (2), and cannot be terminated with a pure resistance. That is, it can be seen that it is reflected. The reflected waveform is transmitted as a backward wave to the amplifier side (input side). Here, when the output end of the amplifier is not terminated, the reflected waveform is reflected again and becomes a traveling wave and is superimposed on the input waveform, which causes waveform distortion. If the shapes of the ground conductors 25 and 28 are determined and arranged so that Cd + Cg is constant as shown in the preferred embodiment, the spiral conductors 24 and 27 can be obtained from the equations (1) and (2).
The characteristic impedance along with can be made constant by eliminating the frequency dependence. This makes it possible to reduce the influence of reflection.

[0025]

As is apparent from the above, according to the present invention, the characteristic impedance along the spiral conductor can be made substantially constant, and the reflection from the traveling wave transmission line can be reduced. Thereby, the waveform distortion is suppressed, and the traveling wave deflecting device can have a wide band.

[Brief description of drawings]

FIG. 1 is a plan view showing a deflecting device according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view taken along the line AA of the deflecting device in FIG.

FIG. 3 is a perspective view showing a part of a deflector.

FIG. 4 is a partially cutaway perspective view showing an insulating base.

FIG. 5 is a plan view of a ground conductor.

FIG. 6 is a side view of a ground conductor.

FIG. 7 is a vertical sectional view of a CRT according to the present invention.

FIG. 8 is a schematic diagram showing inductance and capacitance per turn.

FIG. 9 is a schematic diagram of values of characteristic impedance along a spiral conductor.

FIG. 10 is a sectional view showing a section and a position of the ground conductor.

[Explanation of symbols]

 10 Vertical Deflection Devices 21, 22 First and Second Deflectors 23 First Insulating Base 24 First Spiral Conductor 25 First Earth Conductor 26 Second Insulating Base 27 Second Spiral Conductor 28 Second earth conductor

Claims (1)

Claim: What is claimed is: 1. A first deflector and a second deflector, which are arranged to face each other across an electron beam passage, the first deflector having the first spiral conductor and the first deflector. A first ground conductor disposed inside the spiral conductor, and the second deflector is disposed inside the second spiral conductor and the second spiral conductor. In a traveling wave type deflection device including a second ground conductor, the first and second ground conductors are arranged so that characteristic impedances in directions along the first and second spiral conductors are substantially uniform. A traveling-wave deflector characterized in that the above-mentioned arrangement is provided.