JPH0389437A - Deflection device for in-line type color picture tube - Google Patents

Abstract

PURPOSE:To solve the coma-aberration generated asymmetrically on a screen by providing induction coils arranged near horizontal deflecting coils and aberration correcting coils connected to them and generating the two-pole magnetic field. CONSTITUTION:Electron guns emitting three electron beams 28b, 28g and 28r respectively are arranged in an in-line form on the horizontal line XX, and horizontal deflecting coils are arranged symmetrically across the line XX. A pair of induction coils 14 with several turns are concentrically fitted to the separator 13 of horizontal deflecting coils 11, for example. A pair of aberration correcting coils 15 are connected to coils 14 and provided at the rear ends of deflecting coils 11. Coils 15 are constituted of a pair of unit coils 15a and 15b wound with coils 16b on plate-shaped magnetic substance pieces 16a and generate the two-pole magnetic field 30. Only the center beam 28g is practically deflected, and the occurrence of coma-aberration is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a deflection device for a color picture tube, and more particularly to a deflection device for a color picture tube that improves coma aberration of a scanning screen.

(Prior art) An in-line color picture tube uses an in-line plane that is horizontal to three electron beams arranged in an in-line arrangement, and uses a non-uniform binction magnetic field in a horizontal deflection magnetic field that is perpendicular to the in-line plane, which is parallel to the in-line plane. It is widely used as a self-convergence method that obtains convergence of three electron beams by using a barrel magnetic field as a vertical deflection magnetic field. However, due to the non-uniformity of these deflection magnetic fields, 3
A so-called coma aberration occurs in which convergence deviates between the center beam and side beams of the electron beam.

That is, the scan screen by the center beam becomes smaller than the scan screen by the side beams. Such coma aberration can be easily removed by locally shielding the leakage deflection magnetic field in the convergence cup, which is the final electrode of the electron gun, or by installing a field controller element consisting of a magnetic element that changes the magnetic field distribution. .

(Problem to be Solved by the Invention) However, in recent high-resolution display tubes, the horizontal deflection frequency is lower than the horizontal frequency 1 of the general television system.
From 5.75 KHz, 31.5KH2.

Operation at a high frequency of 84 KH2 has become popular, and the back porch period and front porch period of the retrace period are becoming shorter.

For this reason, when the convergence cup and the magnetic field lines of the high-frequency horizontal deflection magnetic field intersect among the electron gun parts, for example, eddy currents are generated in the convergence cup, resulting in a demagnetizing field, hysteresis of the magnetic element, and AC loss. , which locally weakens the horizontal deflection magnetic field. As a result, misconvergence appears asymmetrically on the screen. That is, as shown in FIG. 6, the center beam g generated at the horizontal deflection start side 60 of the scanning screen is green, and the side beams r and b on the horizontal deflection start side in the horizontal axis X-axis direction of the scanning screen G are scanned in red and blue. This appears as a right-shift phenomenon with respect to screens R and B. This means that the high frequency component of the blanking period of the horizontal deflection current waveform is higher than that during normal scanning by <31.5KH.
For horizontal frequency of z, 100 KHz to 800 KH
z, the demagnetizing field generated when the deflection magnetic field intersects the convergence cup also becomes large, and this particularly affects the center beam g, which has lower deflection sensitivity than the side beam r1b, resulting in the lack of deflection of the center beam 6t. This is because it occurs. This phenomenon occurs approximately 5m from the horizontal deflection start side 60.
This appears only in the - range, resulting in a horizontal coma HCR of 0.3 to 0.4II11 in a 14-inch color picture tube, and appears asymmetrically on the screen, making correction difficult.

The present invention has been made in consideration of the above-mentioned disadvantages, and it is an object of the present invention to provide a deflection device for a color picture tube that eliminates the coma aberration caused by the asymmetry of the screen.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a horizontal deflection coil that generates a horizontal deflection magnetic field;
An in-line color picture tube deflection device comprising: a vertical deflection coil that generates a vertical deflection magnetic field; The present invention provides an in-line color picture tube deflection device comprising an aberration correction coil connected to the coil and generating a dipole magnetic field in substantially the same direction as the horizontal deflection magnetic field by the induced current.

(Function) According to the in-line color picture tube deflection device of the present invention, the main portion of the dipole magnetic field generated by the aberration correction coil with the current of the induction coil induced by the horizontal deflection magnetic field is centered at the tube axis of the color picture tube. That is, it acts on the center beam of the three electron beams arranged in-line. A large induced current is generated during the retrace period, which has a shorter falling time than during the horizontal scanning period, and the dipole magnetic field is generated at the start of scanning to correct the horizontal deflection amount of the center beam.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 shows a self-convergence type in-line color picture tube equipped with a deflection device according to an embodiment of the present invention.

The color picture tube 20 includes a panel 22 having a phosphor screen 21 on the inner surface of which phosphors emitting light in three colors of red, green, and blue are arranged in a dot or stripe shape, and a funnel 23 extending from the periphery of the panel. It has a glass envelope z5 formed by a neck 24 extending from the tip of the funnel. A shadow mask 2B is arranged in the envelope close to the phosphor screen 21, and an in-line electron gun 27 is provided in the neck 24. The electron gun 27 has three electron beams 28r, 28g, and 28b arranged in parallel along one plane, that is, a horizontal plane including the horizontal axis of the screen.
When not deflected, the beam is focused on the center of the screen 21, and consists of a cathode, a control electrode, a focusing electrode, and a convergence cup, with a center beam of 28 g.
A green signal is applied to the side beams 28r and 28b, and video signals of red and blue signals are applied to both side beams 28r and 28b, respectively.

Furthermore, a deflection device IO is attached to surround the funnel 23. As shown in FIGS. 2 and 3(a) and 3(b), the deflection device IO has a pair of saddle-wound horizontal deflection coils 11 and a pair of toroidal-wound vertical deflection coils 12, each held by a separator 13.

The horizontal deflection coil 11 generates a horizontal deflection magnetic field in the form of a binction, and the vertical deflection coil 12 generates a vertical deflection magnetic field in the barrel shape. Note that the horizontal deflection magnetic field in the present invention refers to a magnetic field that deflects electron beams in the same plane direction in which the electron beams are arranged in parallel.

For example, a pair of induction coils 14 having several turns are attached to the separator 13 substantially concentrically with the horizontal deflection coil 11 .

That is, this coil receives the horizontal deflection magnetic field generated by the horizontal deflection coil 11 and converts the change into an induced current.

Further, a pair of aberration correction coils 15 are provided on both the deflection coils 1.
It is attached to the rear end of 1.12, that is, on the electron gun 27 side. The aberration correction coil t5 consists of a pair of single coils 15a and 15b, each of which has a coil 18b wound around a plate-shaped magnetic piece 16a with one end tapered. It is attached to the resin board 29 at a symmetrical position with the tapered end sandwiching the center beam 28g. The magnetic field generated from this aberration correction coil 15 becomes a bipolar magnetic field 30 as shown in FIG. The portion substantially acts only on the center of the tube axis of the color picture tube, that is, on the center beam 28g of the three electron beams arranged in-line. That is, as shown by the arrows in the figure, the center beam 28g is deflected more horizontally than the side beams 28r and 28b.

FIG. 1 shows the aberration correction coil 15 shown in FIGS. 2 to 4.
2 shows a circuit for supplying the induced current excited to the induction coil 14. Unit coil 15a.

A variable resistor 17 is connected in series between the aberration correction coils 15 to which the pair of coils 15b are directly connected.

FIG. 5 explains the operation of the embodiment of the present invention. The horizontal deflection current IH flowing through the horizontal deflection coil 11 has a sawtooth waveform, and the current changes slowly during the scanning period, so the horizontal deflection magnetic field is generated. Almost no induced current is generated in the induction coil 14 due to this. However, during the retrace period, the magnetic field changes rapidly and the change in magnetic flux density is the largest, so a large induced current 1i is generated in the induction coil 14.

Hereinafter, the effect of eliminating the aberration of the center beam shifting to the right of the screen due to the magnetic field of the aberration correction coil 15 due to this induced current will be explained.

After the blanking period, the electron beam is deflected to the left side of the screen, and at the start of the scanning period, it is deflected to the right side of the screen.

The start of scanning on the left side of the screen is the moment when the horizontal deflection magnetic flux that has increased downward during the retrace period begins to decrease, and the induction coil 14 reduces the magnetic field of the aberration correction coil 15 that was generated during the retrace period. It's time to be influenced. Since the deflection magnetic flux changes rapidly during the flyback period, an induced current It flows in the induction coil in a direction that attempts to prevent the change in the deflection magnetic field.

This induced current flows into the aberration correction coil 15 and flows downward into the aberration correction coil 15.
Since a polar magnetic field is generated and is flowing even at the moment of starting scanning, the center beam is deflected to the left side of the screen and the HCR right deviation is corrected. This induced current amount is determined by the variable resistor 1 shown in Figure 1.
Adjust with step 7 to get the appropriate value. According to this embodiment, the HCR right-shift aberration can be corrected with ease of handling without passing a horizontal deflection current directly to the aberration correction coil.

In addition to the above-mentioned embodiments, as a modification of the present invention, an auxiliary coil is wound around the core lea of the aberration correction coil 15 separately from the coil 18b, and a horizontal deflection current is directly passed through this to superimpose a magnetic field that also serves as a field controller. You may. In this case, the field controller for the magnetic element can be omitted.

[Effects of the Invention] As described in the embodiments above, according to the present invention, the aberration correction coil uses the induced current generated in the induction coil provided near the horizontal deflection coil to correct the horizontal deflection magnetic field caused by the horizontal deflection coil. By forming a bipolar magnetic field that acts on the center beam in the same direction, it is possible to easily eliminate asymmetric coma aberration that occurs at the start side of the scanning screen, which was difficult to correct with conventional equipment, and is suitable for high-resolution color display tubes. A suitable in-line color picture tube deflection device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a deflection device for a color picture tube according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a color picture tube equipped with the deflection device of FIG. 1, and FIG. 3(b) is a front view of FIG. 2 as seen from line B-B in the direction of the arrow, and FIG. 4 is a schematic diagram explaining the operation of the aberration correction coil. , FIG. 5 is a waveform diagram illustrating the current excited in the induction coil, and FIG. 6 is a plan view illustrating coma aberration occurring on the scanning start side of the scanning screen. lO... Deflection device, 11... Horizontal deflection coil, 12... Vertical deflection coil, 14... Induction coil, 15... Aberration correction coil, 17... Variable resistor, 20... Color Picture tube, 27...In-line electron gun

Claims (1)

[Claims] In an in-line color picture tube deflection device comprising a horizontal deflection coil that generates a horizontal deflection magnetic field and a vertical deflection coil that generates a vertical deflection magnetic field, the deflection device is arranged near the horizontal deflection coil and receives the horizontal deflection magnetic field. an induction coil that generates an induced current;
An in-line color picture tube deflection device comprising an aberration correction coil that generates a polar magnetic field.