JPH0364839A - Deflecting device for in-line color picture tube - Google Patents

Abstract

PURPOSE:To dissolve coma aberration arising in picture asymmetry by generating barrel field on the scan picture starting side only with a control circuit containing a transistor and a control coil. CONSTITUTION:Once horizontal deflection current (I) from a horizontal output circuit 32 is supplied to a horizontal deflection coil 21 which is made up with a pair of coils connected in parallel, it is supplied in part to an auxiliary coil 24 via a control circuit 31 containing a transistor 33 and a control coil 34. As the control coil 34 changes in impedance with frequency, the impedance rises (falls) in a fly-back period of the horizontal deflection current (I), the transistor 33 is electrified to energize the auxiliary coil 24, and barrel field arises to perform the correction of coma aberration of a center beam 18g on the scan picture starting side. It is thus possible to dissolve the coma aberration appearing in picture asymmetry.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a deflection device for an in-line color picture tube, and particularly to a deflection device suitable for a picture tube operating at a high deflection frequency.

(Prior Art) In general, an in-line color picture tube equipped with an in-line electron gun and a shadow mask uses a binction magnetic field for the horizontal deflection magnetic field and a barrel for the vertical deflection magnetic field, with the in-line direction of three electron beams being horizontal. It is widely used as a self-convergence method because it can converge three electron beams by using a magnetic field. However, as the screen surface becomes flat and the difference between its curvature and the deflection curvature of the electron beam increases, it is necessary to increase the nonuniformity of the deflection magnetic field, and accordingly, the center beam and side beam of the three electron beams are The deflection sensitivity will differ. That is, the deflection sensitivity of the center beam is lower than that of the side beams, and coma aberration as shown in FIG. 7 appears conspicuously as a screen pattern. That is, coma aberration VCR on the vertical axis y at the top and bottom of the screen and coma aberration HCR on the horizontal axis X at the left and right sides of the screen occur, and in a 14-inch 90-degree deflection color picture tube, VCR is 1.
0 to 2.0 mm, HCR is about 0.5 mm. Conventionally, such coma aberration has been eliminated by installing a field controller element within the convergence cup, which is the final electrode of the electron gun, as shown in FIG. This element is made of a highly permeable material, and has a ring-shaped magnetic element 81 surrounding the beams for both side beams. The magnetic piece 82 is placed and corrected.

(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 to 31.5 KHz.

The frequency is set as high as 64 KHz, and the back porch period and front porch period of the retrace period tend to be shortened.

For this reason, as shown in FIG. 8, the convergence cup 80 is caused by the magnetic field lines 83 of a particularly high frequency horizontal deflection magnetic field that intersects with the electron gun component, for example, the convergence cup 80.
An eddy current 84 is generated, and the resulting demagnetizing field 85 causes hysteresis of the magnetic element and alternating current loss, thereby weakening the horizontal deflection magnetic field. This causes asymmetrical misconvergence between the left and right sides of the screen. A representative example of this is the center beam shift to the right phenomenon that occurs at the horizontal deflection start side 90 shown in FIG. This is because the high frequency component of the deflection magnetic field during the retrace scanning period of the horizontal deflection current waveform is higher than during normal scanning, so when this deflection magnetic field intersects the convergence cup, the diamagnetism generated is also large, resulting in a center beam with low deflection sensitivity. This is because an insufficient deflection 91 of the center beam occurs due to a particular influence on the center beam, and an insufficient correction 92 of coma aberration occurs on the horizontal deflection start side. This phenomenon appears only in a range of about 5111ffl on the horizontal deflection start side 90, and the horizontal coma HC of 0.3 to 0.4 aoa in a 14-inch color picture tube.
R, which is inconvenient for display applications, and also appears asymmetrical on the screen, making it difficult to correct.

The present invention has been made in consideration of the above-mentioned disadvantages, and it is an object of the present invention to provide an in-line 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 includes an in-line electron gun that emits three electron beams in parallel along the same plane, and generates a deflection magnetic field perpendicular to the plane. an auxiliary coil that generates a barrel-shaped magnetic field in a direction perpendicular to the plane, and a second deflection coil that generates a deflection magnetic field parallel to the plane; An in-line device comprising: a control circuit including a transistor and a control coil or a capacitor that supplies a part of the deflection current of the first deflection coil to the coil and controls the current of the auxiliary coil according to the frequency of the deflection current. This is a deflection device for color picture tubes.

(Function) According to a specific example of the present invention, the same plane is a plane along the horizontal pongee on the picture tube screen, and the deflection magnetic field perpendicular to this plane becomes the horizontal deflection magnetic field by the first deflection coil. . A pair of auxiliary coils are arranged vertically across three parallel electron beams with the center beam as the center, and generate a barrel magnetic field by superimposing the horizontal deflection magnetic field. Therefore, due to this barrel shape, the center beam is more strongly deflected in the horizontal direction than both side beams. The pair of auxiliary coils are connected in series, and a control circuit including a transistor and a control coil (or capacitor) is connected thereto to supply a portion of the horizontal deflection current that energizes the first deflection coil. Since the control coil (or capacitor) changes impedance depending on the frequency,
The impedance increases during the retrace scan period of the horizontal deflection current (
(lowering), turns on the transistor, energizes the auxiliary coil, generates the barrel magnetic field, and corrects the coma aberration of the center beam at the start side of the scanning screen.

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

FIG. 1 shows one embodiment of the present invention, which is a self-convergence type in-line color picture tube. The color picture tube 10 has a panel 12 having a phosphor screen 11 in which phosphors emitting light in three colors of red, green, and blue are arranged in dots on the inner surface, and a funnel 13 extending from the periphery of the panel.
and a glass envelope 15 consisting of a neck 14 extending from the tip of the funnel. A shadow mask 16 is placed in the envelope adjacent to the phosphor screen 11 and an in-line electron gun 17 is provided in the neck 14. The electron gun 17 emits three electron beams 18'', 18g, and 18b in parallel along one plane, that is, a horizontal plane including the horizontal axis of the screen, and so as to be concentrated at the center of the screen 11 when not deflected. , a cathode, a control electrode, a focusing electrode, and a convergence cup, with a green signal on the center beam 18g and both side beams 18r118.
A red video signal and a blue video signal are respectively applied to b.

Furthermore, a deflection device 20 is attached to surround the funnel 13. As shown in FIG. 2, the deflection device 20 includes a pair of saddle-wound horizontal deflection coils 21 and a toroidal-wound vertical deflection coil 22 held by a separator 23, and further includes an auxiliary coil 24. As shown in FIG. 5, the horizontal deflection coil 21 has a horizontal deflection magnetic field 5 of the binction type
As shown in FIG. 6, by making the actual distribution of the coil winding 61 such that a predetermined angle θ from the coil center exceeds a predetermined angle, a non-uniform magnetic field of the vinction type is generated. can occur. Below the above angle, a barrel-shaped non-uniform magnetic field results. In actual design, the value of this angle is changed in the coil axis direction, and a binction type magnetic field is generated overall.

Similarly, the vertical deflection coil 22 has a barrel-shaped vertical deflection magnetic field 52.
occurs. In the case of the toroidal-wound coil that constitutes the vertical deflection coil 22, the shape of the magnetic field can be arbitrarily designed in the same manner as the saddle-shaped coil, depending on the winding distribution of the coil 26 wound around the magnetic core 25 (Fig. 2). Therefore, the required magnetic field distribution can be obtained.

Furthermore, the auxiliary coil 24 is attached to the electron gun 17 side of both the deflection coils 21 and 22. The auxiliary coil 24 has a structure in which a solenoid coil 28 is wound around a plate-shaped magnetic rod 27, and the pair of coils are mounted on a resin board 29 at symmetrical positions perpendicular to the horizontal plane where the three electron beams 18 are lined up, sandwiching the center beam 18g. Attach to. The magnetic field generated from this auxiliary coil 23 is a barrel-shaped magnetic field 3 as shown in FIG.
0, and as shown by the arrow in the figure, the side beam 18r,
The amount of horizontal deflection of the center beam 18g can be increased compared to that of the center beam 18b.

FIG. 3 shows a specific example of a control circuit 31 that controls the supply of a part of the horizontal deflection current to the auxiliary coil 24. At the same time as being supplied to the deflection coil 21, a part of it is supplied to the auxiliary coil 24 via a control circuit 31 including a transistor 33 and a control coil 34. That is, a series circuit of a resistor 35 and a control coil 34 is connected to both ends of the horizontal output terminal in parallel with the horizontal deflection coil 21, and the base electrode 33b of the transistor 33 is connected to the connection point between the resistor 35 and the control coil 34. .

The emitter electrode 33e of the transistor is connected to the other terminal of the control coil 34 and at the same time to one of the output terminals of the horizontal output circuit 32. One end of the auxiliary coil 24 made up of a pair of series coils is connected to the other terminal of the horizontal output circuit 32, and the other end of the auxiliary coil 24 is connected to the collector of the transistor 33 via a variable resistor 36. Since the control coil 34 has an impedance that depends on the frequency, when the base current flows due to the voltage increase between the coils, the transistor becomes conductive, causing current to flow in the auxiliary coil 24 for a certain period of time. That is, as shown in FIG. 4, the horizontal deflection current has a shorter blanking period t2 than the normal horizontal scanning period tl and contains higher frequency components, so when the current flows through the control coil 34,
During this blanking period t2, the impedance becomes large and a base current flows to operate the transistor 33 and energize the auxiliary coil 24. As a result, a barrel magnetic field 30 is generated from the auxiliary coil 24, and since this barrel magnetic field is stronger at the center than at the periphery, the center beam 1 is stronger than both side beams.
8g is strongly deflected. By the above operation, the magnetic field of the auxiliary coil is generated only on the screen scanning start side, which compensates for the lack of coma aberration correction occurring on this side, and eliminates the center beam shift phenomenon.

Note that the variable resistor 36 in the circuit is for adjusting the amount of correction. Using this control circuit, it was possible to easily correct the approximately 0.4 ms coma aberration that occurs in a 14-inch color picture tube.

Although the control circuit has been described in the embodiments above, the present invention is not limited to this, and it goes without saying that various modifications can be applied.

For example, a control capacitor can be used instead of a control coil. Since the impedance of the capacitor decreases as the frequency of the current increases, it is connected in parallel to the resistor 35 for the control circuit of FIG. Furthermore, it can also be used in combination with a coil.

Furthermore, the present invention is similarly applicable to a picture tube without a field controller.

[Effect of the invention] The present invention provides an auxiliary coil separately from the horizontal deflection coil,
A barrel magnetic field perpendicular to the plane that strongly acts on the center beam is formed in the paths of the three electron beams on the same plane, and the barrel magnetic field is controlled by a control circuit including a transistor and a control coil or a capacitor. I made it so that it only occurs on the scanning screen start side, so
This makes it possible to eliminate asymmetric coma aberration, which is difficult to correct, and eliminate the so-called right-shifting phenomenon of the center beam, thereby providing an in-line color picture tube deflection device suitable for high-resolution color display tubes.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the main parts of a color picture tube according to an embodiment of the present invention, FIG. 2 is a plan view showing the deflection device of FIG. 1, and FIG.
Figure 4 is a circuit diagram showing a control circuit for operating the auxiliary coil in Figure 2, Figure 4 is a waveform diagram explaining Figure 3 and shows the waveform of the horizontal deflection current supplied to the horizontal deflection coil and the auxiliary coil. Figure 5 is a schematic diagram explaining the distribution of the deflection magnetic field;
The figure is a schematic diagram to explain the horizontal deflection coil, Figure 7 is a plan view to explain coma aberration, Figure 8 is a diagram to explain the generation of diamagnetic properties due to eddy currents generated in the convergence cup, and Figure 9 is a scanning screen. FIG. 3 is a plan view illustrating comatic aberration that occurs on the scanning start side of FIG. 10...Color picture tube, 17...In-line electron gun, 18r, 18g, 18b-3 electron beams, 20.
...Deflection device, 21...Horizontal deflection coil, 22...Vertical deflection coil, 24...Auxiliary coil, 30...Barrel magnetic field, 31...Control circuit, 33...Transistor, 34... ...Control coil.

Claims (1)

[Claims] It is equipped with an in-line electron gun that emits three electron beams in parallel along the same plane, a first deflection coil that generates a deflection magnetic field perpendicular to the plane, and a deflection magnetic field parallel to the plane. An in-line color picture tube having a second deflection coil that generates an auxiliary coil that generates a barrel-shaped magnetic field in a direction perpendicular to the plane, and a portion of the deflection current of the first deflection coil that is supplied to the auxiliary coil. An in-line deflection device for a color picture tube, comprising: a control circuit including a transistor and a control coil or a capacitor that controls the current of the auxiliary coil according to the frequency of the supplied deflection current.