JPH0417239A - Color cathode-ray tube - Google Patents

Abstract

PURPOSE:To correct deflection of side beams by providing erecting portions extended from the side edge of an annular portion, which independently surrounds a pair of side beams, on a center beam passing hole side toward the center beam passing hole, and disposing tongue piece portions extended contrarily to the erecting portions on the other side. CONSTITUTION:Field controllers 28 comprise annular portions 29 for independently surrounding a pair of side beam passing holes 3B, 3R, erecting portions 30 extended from the side edge of the annular portion 29 on a center beam passing hole 3G side toward the center beam passing hole 3B and having erecting tip ends, and tongue piece portions 31 extended contrarily to the erecting portions 30. Accordingly, it is possible to make uniform an effect of a magnetic field of the field controllers 28 exerted on the pair of side beams and the center beam in the middle of a screen. The pair of side beams can be deflected right more than the center beam, and a phenomenon of deflection shortage of the center beam as compared with the pair of side beams can be corrected. Therefore, right deflection of the screen drawn by the center beam can be eliminated.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a color cathode ray tube, and in particular to a field controller that corrects aberrations due to non-uniformity of the deflection magnetic field of an in-line color picture tube. Concerning an improved color cathode ray tube.

(Prior Art) In general, a color cathode ray tube has an envelope consisting of a panel and a funnel that are joined together, and the tube faces a shadow mask in which a large number of electron beam passage holes are formed, which is attached to the inside of the panel. A phosphor screen consisting of three-color phosphor layers that emit blue, green, and red light is formed on the inner surface of the panel, and the three electron beams emitted from the electron gun disposed inside the neck of the funnel are directed to the outside of the funnel. The phosphor screen is deflected by a magnetic field generated by a deflection yoke attached to the phosphor screen to horizontally and vertically scan the phosphor screen, thereby displaying a color image on the phosphor screen.

In such a color cathode ray tube, the electron gun is particularly an in-line type electron gun that emits three electron beams arranged in a row consisting of a center beam and a pair of side beams that pass on the same horizontal plane. Self-convergence type in-line color cathode ray tubes are widely used in which three electron beams are self-concentrated by a non-uniform magnetic field in which the deflection magnetic field is of a vinch type and the vertical deflection magnetic field is a barrel-type.

However, in this self-convergence type in-line color CRT, the deflection sensitivity of the center beam is lower than that of the pair of side beams due to the non-uniformity of the deflection magnetic field. The screen (IG) drawn by the center beam is smaller than the screens (IB) and (IR) drawn by the beams, and the screen (IG) is smaller on the vertical axis (Y axis) and horizontal axis (X axis) on the top, bottom, left and right of the screen. , :VcR, produces comatic aberration shown by HCR. The magnitude of this coma aberration is, for example, in a 14-inch 90-degree deflection color picture tube and a VCR of 1.0 to 2.0.
+am, HCR will be about 0.5+sm.

Therefore, conventionally, this type of color cathode ray tube
This comatic aberration is removed by placing a field controller at the inner bottom of a convergence cup attached to the electron beam emission end of the electron gun. That is, as shown in FIG. 7, three electron beam passing holes <8B) and (3G) formed at the bottom of the convergence cup (2)
, (31?), a pair of side beam passing holes (3
B) A field controller (4) consisting of an annular high permeability magnetic element surrounding (3R).
) are placed. By arranging the field controller (4) around the pair of side beam passage holes (3B) and (3R) in this way, the screen drawn by the center beam is enlarged both horizontally and vertically; The screen drawn by is reduced in both the horizontal and vertical directions, so that the three-color screen can be made to match by removing coma aberration that occurs due to the non-uniformity of the deflection magnetic field.

However, in recent high-resolution color display tubes, the horizontal deflection frequency has been set high from 15.75kHz to 31.5kHz, and high-sensitivity deflection yokes are often used to reduce deflection power. There is.

When a high-sensitivity deflection yoke is used in this way, the horizontal deflection rear leakage magnetic field leaking to the rear of the deflection yoke becomes large.
The action of the field controller (4) in the horizontal deflection direction is enhanced, and as shown in FIG. 8, the screen (IG) drawn by the center beam is expanded only in the horizontal direction.

As a means to solve this problem, Japanese Patent Publication No. 53-136476
No. 57-1762836 and Japanese Unexamined Patent Publication No. 57-1762836,
As shown in Figure 9, a pair of side beam passing holes (3B
), an annular portion (5R) arranged to surround (3R)
), the field controller (4) is provided with a three-dimensional part (6) that extends from the side edge of the center beam passage hole (3G) toward the center beam passage hole (3G) and has its tip erected. ), and as shown in FIG.
G) Place the field controller (4) provided with the tongue piece (7) extending from the side edge toward the center beam passage hole (3G), and
A device is shown in which the leakage magnetic field after the horizontal deflection during Bunraku is reduced, thereby correcting the horizontal deviation of the screen drawn by the center beam.

However, if the field controller (4) provided with the three-dimensional part (6) and the tongue part (7) as described above is used for a color CRT with a horizontal deflection frequency of 31.5 kHz or more, such as recent color display tubes, The field controller (4) is magnetized by the rear leakage magnetic field of horizontal deflection, and as shown in Figure 11, the screen (1G) drawn by the center beam at both left and right ends of the screen is drawn by a pair of side beams. Misconvergence occurs where the screen shifts to the right with respect to the screens (IB) and (IR).

The reason why such misconvergence occurs is that when the electron beam is deflected to scan from the left to the right of the screen by the horizontal deflection magnetic field of the deflection yoke, the magnetic flux density in the field controller (4) increases as shown in Figure 12. When drawing the hysteresis curve (9) shown below and scanning the center of the screen, B1
A residual magnetism of the magnitude shown remains. Therefore, due to the residual magnetism of this field controller (4), the electron beam passing holes (3B), (3G)
, generates a magnetic field (lO) near (3R) indicated by a broken line arrow. This magnetic field (10) is a center beam (IIG
), a pair of side beams (IIB), (IIR)
center beam (IIG) in the center of the screen.
A pair of side beams (IIB).

(IIR) is deflected to the right, resulting in a misconvergence in which the center beam (IIG) is relatively shifted to the left. However, since misconvergence at the center of the screen is usually corrected by a static magnet, it appears as misconvergence in which the center beam (IIG) is relatively shifted to the right at both left and right ends of the screen.

This amount of deviation increases by increasing the size of the field controller due to the addition of the three-dimensional part (6) and the tongue part (7), and the amount of magnetization increases to more than 0.31μ on the left and right sides, and high convergence characteristics are required. This has become a serious problem for high-resolution color display tubes.

(Problem to be Solved by the Invention) As described above, the electron gun is an in-line type electron gun that emits three electron beams arranged in a row consisting of a center beam and a pair of side beams passing on the same horizontal plane, and a deflection device A self-convergence type in-line color cathode ray tube that self-converges three electron beams has a horizontal deflection magnetic field of a binction type and a vertical deflection magnetic field of a barrel type as a nonuniform magnetic field.Due to the nonuniformity of its deflection magnetic field,
The deflection sensitivity of the center beam is lower than the deflection sensitivity of the pair of side beams, and comatic aberrations occur on the top, bottom, left and right sides of the screen drawn by the three electron beams. Therefore, in conventional electron guns, out of the three electron beam passing holes formed at the inner bottom of the Humbarzens cup attached to the electron beam emission end, the side beam passing hole is surrounded by a pair of side beam passing holes. An annular field controller made of high-permeability magnetic elements is placed around it to correct coma aberration.

However, in recent high-resolution color display tubes, the horizontal deflection frequency has been set high from 15.75kHz to 31.5kHz, and high-sensitivity deflection yokes are often used to reduce deflection power. There is.

Therefore, when using a highly sensitive deflection yoke like this,
The horizontal deflection rear leakage magnetic field leaking to the rear of the deflection yoke is greatly expanded, and the action of the field controller in the horizontal deflection direction is promoted, so that the screen drawn by the center beam is expanded only in the horizontal direction.

As a means to solve this problem, an annular part arranged to surround a pair of side beam passage holes is made to extend from the side edge of the center beam passage hole toward the center beam passage hole, and the tip thereof is For a field controller with a three-dimensional part with an upright part and an annular part,
A field controller equipped with a tongue extending from the side edge of the center beam passage hole toward the center beam passage hole is used to reduce the horizontally deflected rear leakage magnetic field that bunrakus into the center beam passage hole. This figure shows a system in which the horizontal deviation of the screen drawn by the center beam is corrected.

However, if you use a field controller with a three-dimensional part or a tongue part as described above on a color cathode ray tube with a horizontal deflection frequency of 31.5 kHz or higher, such as recent color display tubes, the field controller will be affected by the leakage magnetic field after the horizontal deflection. is magnetized and residual magnetism remains, and this residual magnetism causes misconvergence in which the screen drawn by the center beam shifts to the right at both left and right ends of the screen relative to the screen drawn by the pair of side beams. This is a serious problem for high-resolution color display tubes that require high convergence characteristics.

This invention was made to solve the above-mentioned problems, and it solves the problem of misconvergence, which cannot be solved even if a three-dimensional part is provided for the annular part arranged to surround a pair of side beam passage holes. The purpose is to eliminate the misconvergence in which the screen drawn by the center beam at both left and right ends shifts to the right with respect to the screen drawn by the pair of side beams, and to construct an electron gun suitable for high-resolution color display tubes, etc. do.

[Structure of the Invention (Means for Solving the Problems) Formed at the bottom of a convergence cup at the tip of an electron gun that emits three electron beams arranged in a row consisting of a center beam and a pair of side beams passing on the same plane. In a color picture tube, a field controller for correcting aberrations due to non-uniformity of the deflection magnetic field is arranged around a pair of side beam passing holes among three electron beam passing holes arranged in a row. The field controller includes an annular portion surrounding each of the pair of side beam passage holes, and a three-dimensional portion extending from the side edge of the annular portion on the side of the center beam passage hole toward the center beam passage hole and having an upright tip. and a tongue portion extending in a direction opposite to the three-dimensional portion from the side edge of the annular portion opposite to the center beam passage hole.

(Function) As described above, a solid portion is provided extending from the side edge of the center beam passage hole to the center beam passage hole in the annular portion that surrounds each of the pair of side beam passage holes, and a solid portion is provided on the opposite side. If a tongue piece part extending in the opposite direction is provided,
The influence of the field controller's magnetizing magnetic field on the pair of side beams and center beam at the center of the screen can be equalized, and because the conventional three-dimensional part is provided, the pair of side beams are deflected to the right more than the center beam, By correcting the phenomenon in which the center beam is insufficiently deflected relative to the side beams, it is possible to eliminate the right shift of the screen drawn by the center beam.

(Example) Hereinafter, the present invention will be described based on an example with reference to the drawings.

FIG. 1 shows an in-line color picture tube that is one embodiment of the present invention. This color picture tube has an envelope consisting of a panel (20) and a funnel (21) that are joined together, and a shadow formed with a large number of electron beam passing holes installed inside the panel (20). Opposed to the mask (22), on the inner surface of the panel (20) are 3 lights that emit light in blue, green, and red.
A phosphor screen (23) made of a color phosphor layer is formed. Also, the neck (24) of the funnel (21)
An electron gun (25) that emits three electron beams arranged in a row, consisting of a center beam (IIG) and a pair of side beams (IIB) and (IIR) passing on the same horizontal plane, is disposed within the electron gun (25). Furthermore, on the outside of the funnel (21), three electron beams (
A deflection yoke (26) is attached that generates a deflection magnetic field that deflects IIB), (IIG), and (IIR) in horizontal and vertical directions.

The electron gun (25) has three cathodes arranged in a row in the horizontal direction, a grid that controls electron emission from the cathodes, and an electron beam emitted through this grid toward a phosphor screen (23). A convergence cup (27) made of a non-magnetic material is attached to the most advanced grid. There is. This Convergence Cup (27)
As shown in Figures 2 and 3, the bottom of the
Three electron beam passing holes (3B
).

(3G), (31?) are formed in a row in the horizontal direction, and the pair of side beam passing holes (3B>, (3
Field controllers (28) made of a highly permeable material are arranged so as to surround each of R) separately.

This field controller (28) has an annular portion (29) surrounding each side beam passage hole (3B) and (3R).
) and the center beam passage hole (3) of this annular part (29).
B) A three-dimensional part (3B) extending from the side edge toward the center beam passage hole (3B) and having an upright tip
0) and the center beam passage hole (
3B) consists of a tongue piece part (31) extending in the opposite direction to the three-dimensional part (30) from the side edge on the opposite side.

Specifically, such a field controller (28) has a maximum diameter in the vertical direction (the annular portion (29) has the same diameter in the vertical direction).
is 6 degrees, the height of the three-dimensional part is 6 degrees, and the center beam passage hole (
3B), the distance between the three-dimensional parts (30) facing each other is 5 degrees,
The horizontal protrusion length of the tongue portion (31) from the annular portion (29) is 1.5 mm, and the center beam passage hole (
The distance between the three-dimensional parts (30) facing each other with the side beam passing holes (3B) and (3R) in between is approximately 4 the distance between the pair of side beam passage holes (3B) and (3R).
It is 0%.

By the way, as mentioned above, if the field controller is placed in the area covered by the leakage magnetic field from the rear of the horizontal deflection of the deflection yoke, it will be magnetized by the leakage magnetic field from the rear of the horizontal deflection and residual magnetism will remain (see Figure 12). When scanning from left to right on the screen, the magnetic field (33) shown by the dashed arrow in FIG. 4 is generated even in the center of the screen where the magnetic field of the deflection yoke is zero due to the residual magnetism. This magnetic field (33) acts on each electron beam (IIB), (IIG), (IIR), but in a conventional field controller, the force Fs acting on each side beam (IIB), (IIR) is ) is larger than the force Fc acting on F s
>F e, whereas in the field controller (28) of this example, the three-dimensional part (30) is located close to the center beam passage hole (3B) and is formed above a certain height, so that the center beam The force Fc acting on (IIG) is made larger than before, so that Fs = Fc.

As a result, with respect to the screen drawn by the conventional center beam or the screen drawn by a pair of side beams, there is a shift to the right of 0.3 mm at both left and right ends, and the amount of rightward shift of the center beam is 0.3 mm. The misconvergence of h+m can be reduced to 0.1 mm or less.

Field controller with this kind of action (28)
can be obtained by setting the distance between the three-dimensional parts (30) facing each other with the center beam passage hole (3B) in between, as described above, to be approximately 40% of the distance between the pair of side beam passage holes (3B) and (3R). However, since the amount of rightward deviation of the center beam differs depending on the type of color picture tube, setting the interval to the optimum value is determined based on the screen size, deflection angle, deflection yoke design, etc. that are related to the amount of rightward deviation. be done.

For example, when a saddle-toroidal type deflection yoke is attached to a 13-inch 90-degree deflection color picture tube, what is the height of the three-dimensional part (30) and the amount of rightward deviation of the center beam relative to the maximum diameter in the vertical direction of the field controller (28)? , there is the relationship of the curve (34) shown in FIG. 5(a), and the side beam passage hole (3B).

(3R) The distance between the three-dimensional parts (30) and the amount of rightward deviation of the center beam is expressed by the curve (35) shown in FIG. 5(b).
There is a relationship as follows, and it is necessary to appropriately set the height and interval of the three-dimensional portion (30) according to the amount of rightward deviation of the center beam.

However, if the dimensions of the three-dimensional part (30) are determined so that the amount of rightward deviation of the center beam is zero as described above, the vertical coma aberration V, which was conventionally adjusted by the outer diameter of the annular part, is reduced.
This will interfere with CR settings. That is, when the outer diameter of the annular portion (29) is changed in order to eliminate the vertical coma aberration VCR, the interval between the three-dimensional portions (30) changes. In other words, if the outer diameter of the annular portion (29) is reduced, the three-dimensional portion (30
) The spacing widens, and conversely, when the outer diameter of the annular portion (29) is expanded, the spacing between the three-dimensional portions (30) narrows. Therefore, simply by providing the three-dimensional portion (30) in the annular portion (29), it is not possible to correct the amount of rightward shift of the center beam regardless of the vertical coma aberration VCR.

However, the tongue portion (31) is located in the opposite direction to the three-dimensional portion (30).
), the vertical deflection magnetic field is focused by the tongue portion (31), passes through the annular portion (29), and is directed to the three-dimensional portion (3).
0) to the center beam passage hole (3G) side, and depending on the horizontal length of the tongue piece (31),
Center beam passage hole (3G) that focuses the vertical deflection magnetic field
The amount guided to the side changes. On the other hand, this tongue piece part (31) is
Three electron beam passage holes (3B), (3G).

Since it is located outside of (3R) in the horizontal direction, it has no focusing or shielding effect on the horizontal deflection magnetic field, and has almost no effect on the horizontal deflection magnetic field.

Therefore, by setting the horizontal length of the tongue portion (31) appropriately, the three-dimensional portion (30) is set so that the amount of rightward deviation of the center beam becomes zero, and the outer part of the annular portion (29) is Even if the diameter changes, the coma aberration VCR based on the change in the outer diameter of the annular portion (29) can be reduced by
) can be adjusted without changing the appropriate settings, and the shift to the right of the screen drawn by the center beam, which conventionally occurs, can be easily resolved.

[Effect of the invention] Three electron beams arranged in a row are formed at the bottom of a convergence cup at the tip of an electron gun that emits three electron beams arranged in a row consisting of a center beam and a pair of side beams passing on the same plane. Among the passage holes, the center beam passage hole of the annular part surrounding each of the pair of side beam passage holes is provided with a three-dimensional part extending from the side edge toward the center beam passage hole, and on the opposite side thereof, a three-dimensional part is provided in the opposite direction to the three-dimensional part. Providing a tongue section that extends to the center of the screen can equalize the influence of the field controller's magnetizing magnetic field on the pair of side beams and center beam at the center of the screen. On the other hand, it is possible to correct the phenomenon in which the center beam is insufficiently deflected and the paired side beam is deflected to the right more than the center beam, thereby eliminating the right shift of the screen drawn by the center beam. It can be applied to resolution color display tubes with good results.

[Brief explanation of the drawing]

1 to 5 are detailed explanatory diagrams of the present invention, with FIG. 1 showing the configuration of a color cathode ray tube as an embodiment thereof, and FIGS. 2(a) and 2(b) showing the convergence cup thereof. 3 is a perspective view of the field controller, FIG. 4 is a diagram for explaining the operation of the field controller, and FIGS. 5(a) and (b) ) are diagrams showing the relationship between the height of the solid part and the amount of rightward deviation of the center beam with respect to the maximum diameter of the field controller, and the relationship between the distance of the solid part and the amount of rightward deviation of the center beam with respect to the distance between a pair of side beam passage holes, respectively. Figures 6 to 13
The figure is an explanatory diagram of a conventional color picture tube, Figure 6 is an explanatory diagram of coma aberration that occurs in a self-convergence type inline color cathode ray tube, and Figures 7 (a) and (b) are respectively diagrams showing the bottom of a conventional convergence cup. A plan view and a cross-sectional view showing the configuration of the field controller arranged. Fig. 8 is an explanatory diagram of the deviation of the screen drawn by the center beam when the horizontal deflection frequency is set high. Fig. 9 is an illustration of the displacement of the screen drawn by the center beam when the horizontal deflection frequency is set high. Fig. 10 is a perspective view of a field controller provided with a tongue portion, and Fig. 11 shows the deviation of the screen drawn by the center beam when using a field controller provided with a three-dimensional portion. FIG. 12 is a diagram for explaining the magnetization of the field controller by the horizontal deflection magnetic field, and FIG. 13 is a diagram showing the magnetic field formed by residual magnetism when the field controller is magnetized. 3B, 3R... A pair of side beam passing holes, 3B...
・Center beam passage hole, 11B, IIR...Pair of side beams, 11B...
- Center beam, 23... Phosphor screen, 25... Electron gun, 2B... Deflection yoke, 27.
... Convergence cup, 28... Field controller, 29... Annular part, 31... Tongue piece part. 30... three-dimensional part,

Claims (1)

[Claims] A convergence cup is attached to the tip of an electron gun that emits three electron beams arranged in a row consisting of a center beam and a pair of side beams that pass on the same plane, and a convergence cup is formed at the bottom of the convergence cup. A field controller is arranged around a pair of side beam passing holes among the three electron beam passing holes arranged in a row through which each of the three electron beams passes through, respectively, to correct aberrations based on the non-uniformity of the deflection magnetic field. In the color cathode ray tube, the field controller includes an annular portion surrounding each of the pair of side beam passage holes, and a tip portion extending from a side edge of the annular portion beside the center beam passage hole toward the center beam passage hole. and a tongue portion extending in a direction opposite to the three-dimensional portion from the side edge of the annular portion opposite to the center beam passage hole. color cathode ray tube.