JPS6394542A - Beam spot correcting device - Google Patents

Abstract

PURPOSE:To constitute this device at a low cost and reduce the load of its power supply by utilizing a saturable reactor bridge to feed the parabola wave current into the coil of a correcting yoke. CONSTITUTION:A correcting yoke, e.g., electromagnetic quadruple-pole correcting yoke, installed on a neck section NC and a saturable reactor bridge 4 connected in series to a horizontal deflecting coil 3 are provided. The sawtooth wave current of a horizontal cycle flows through the horizontal deflecting coil 3, therefore the sawtooth wave current flows also through the saturable reactor bridge 4 connected in series to this horizontal deflecting coil 3, and the parabola wave current of a horizontal cycle flows through the coil 2 of a correcting yoke 1 connected to the coil constituting this saturable reactor bridge 4. Accordingly, the saturable reactor bridge 4 connected in series to the horizontal deflecting coil 3 is utilized to feed the parabola wave current into the coil 2, no external correcting circuit is required, this device can be constituted at a low cost, and the load of its power supply can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a correction device for correcting the beam spot size of a cathode ray tube.

[Summary of the invention]

The present invention is a correction device for correcting the beam spot size of a cathode ray tube, which utilizes a saturable reactor bridge to flow a parabolic wave current through the coil of the correction yoke, and can be constructed at low cost. This allows the burden of tXm to be reduced.

[Conventional technology]

The influence of deflection distortion caused by the deflection yoke is large in the peripheral area of the screen of a cathode ray tube, and the beam spot size becomes large in the peripheral area of the screen, which is one of the causes of a reduction in resolution. This phenomenon is noticeable in CFD yokes (convergence free deflection yokes) and becomes even more noticeable in large cathode ray tubes.

As a means to solve this problem, we installed four electromagnetic meters on the outside of the neck.
It is known to provide a polar correction yoke. Figure 5 shows
This is an example of an in-line three-beam color cathode ray tube, such as the Trinitron®.

In the same figure, K vt SK (2, KB is the cathode, G1-G5 are the first to fifth grids, C0NV
is the convergence electrode, AG is the aperture grill, B,
G and R are fluorescent surface stripes. The second grid G2 and the third grid G3 constitute a prefocus lens, and the electron beam is bent slightly inward around the green.

Each beam BR% 80% BB intersects at the center of a main focus lens with a large diameter formed by the third grid G3, the fourth grid G4, and the fifth grid G5. After the red and blue beams BR and BB intersect, they once spread outward and are deflected by convergence 'tJlicONν so that they are concentrated on the fluorescent surface. Each beam B R-, B a-, B that passed through the convergence electrode C0NV
e intersects at the slit part of aperture grill AG,
The fluorescent surface stripes B, G, and R are reached.

(1) is an electromagnetic four positive pole correction yoke for beam spot correction arranged corresponding to the portion of the fourth grid G4 where each of the beams B R and B 0% B s intersects. As shown in FIG. 6, this correction yoke (1) consists of a pair of U-shaped yokes (1a) and (lb), and this yoke (la)
and (1b) are red, green,
It is perpendicular to the plane containing the blue beams BR, BO, and Be, and is arranged symmetrically on both sides of the intersection of the beams Bvt, Ba, and Bs. A coil (2) is wound around the yokes (1a) and (lb), and the coil (2) of the correction yoke (1) receives, for example, a horizontally periodic parabolic wave current in the direction shown in the figure. be swept away.

In this case, the yokes (1a) and (1b) of the correction yoke (1)
) has the polarity as shown, and lines of magnetic force are generated as shown by the broken lines. Therefore, each beam B Rs B G %B
Forces f1 to f4 act on B in the vertical and horizontal directions, and each beam B
n −, B G % B B is deformed so that it is compressed in the vertical direction and expanded in the horizontal direction.

This deformation is small for the beam reaching the center of the screen, but large for the beam reaching the periphery of the screen. Therefore, the beam spot size at the periphery of the screen is corrected, and resolution is improved.

Correcting the beam spot size by disposing the correction yoke 11) on the outside of the neck portion NG in this way is described in detail in, for example, Japanese Patent Application No. 57-230602.

[Problem that the invention seeks to solve]

However, in order to obtain the parabolic wave current flowing through the correction yoke (11), a special external correction circuit was required in the past and was expensive.Also, the driving power was large,
There was also the inconvenience of increasing the burden on employees.

In view of these points, the present invention can be constructed at low cost, and the burden on the power source can be reduced.

[Means for solving problems]

The present invention includes a correction yoke provided in the neck part NC, for example, an electromagnetic quadrupole correction yoke +11, and a horizontal deflection coil (3
) and a saturable reactor bridge (4) connected in series with the saturable reactor bridge (4), and the horizontally periodic parabolic wave current from the saturable reactor bridge (4) is made to flow through the correction coke coil.

[Effect]

In the above configuration, a horizontally periodic sawtooth wave flow flows through the horizontal deflection coil (3). Therefore, a sawtooth wave flow flows through the saturable reactor bridge (4) connected in series with this horizontal deflection coil <3), and the correction yoke is connected between the coils constituting this saturable reactor bridge (4). A parabolic wave current with a horizontal period flows through the coil.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In this example, the horizontal deflection coil (
A saturable reactor bridge (4) is connected in series with 3). That is, in FIG. 1, (4A) to (4D) are the first to fourth coils constituting the saturable reactor bridge (4), and the horizontal deflection coil (3) includes the first coil (4D).
4^) and a series circuit of the fourth coil (4D) and a parallel circuit of a series circuit of the third coil (4C) and the second coil (4B) are connected.

In addition, the first coil (4A) and the fourth coil (4D)
Coil (2) (the second coil) of the electromagnetic four city pole correction yoke (1) for beam spot correction is connected between the connection point P1 of (see Figure 5) are connected.

The saturable reactor bridge (4) is specifically configured as shown in Figure 2. In the figure, (11) is a U-shaped core having magnetic legs (12) and (13), and (14) is a T-shaped core having magnetic legs (15). The magnetic legs (15) of the core (14) cause the core (11
) magnetic legs (12) and (13) are formed.

A magnet (16) is interposed between the magnetic leg (12) of the core (11) and one end of the core (14).
A magnet (17) is interposed between the magnetic leg (13) of 11) and the other end of the core (14).

Further, a coil bobbin (18) is attached to the magnetic leg (12), and this coil bobbin (18) has a first coil (4A) and a second coil (4A) as shown in FIG.
B) is wound with bifilar winding.

In this way, the first coil (4^) and the second coil (4^)
Since B) is bifilar-wound, the magnetic properties of the first coil (4^) and the second coil (4B) are equal to each other. On the other hand, a coil bobbin (19) is attached to the magnetic leg (13).
), as shown in FIG. 3, a third coil (4C) and a fourth coil (4D) are wound with bifilar winding. In this way, the third coil (4C) and the fourth coil (4D) are bifilar wound.
The magnetic properties of the fourth coil (4c) and the fourth coil (4D) are equal to each other. Coil bobbin (1B) and (1
9) C. When current in the same direction is passed through the coils (4A), (4B), (4c), and (4D) wound twice, the direction of the generated magnetic flux is the same as that of the magnets (16) and (17).
) so that one side is in the same direction and the other side is in the opposite direction with respect to the bias magnetic flux from.

In the above configuration, the horizontal deflection coil (3) is
When a horizontally periodic sawtooth reduced current flows as shown in Figure B, the coil bobbin (18 ) and a coil (4A) wound around (
4B), a magnetic flux in the opposite direction to the bias magnetic flux (indicated by the r&line arrow) is generated as shown by arrow A in Fig. 2, and the coil (4C) wound around the coil bobbin (19)
, (4D), a magnetic flux in the same direction as the bias magnetic flux is generated as shown by arrow B in FIG.

The inductance of the coil decreases as the magnetic flux increases. The magnetic flux of the coils (4A) and (4B) decreases because they are in the opposite direction to the bias magnetic flux, and the inductance of the coils (4A) and (4B) increases, and the coil (
The magnetic fluxes of coils (4C) and (4D) increase because they are in the same direction as the bias magnetic flux, and the inductances of the coils (4C) and (40) decrease.

As the inductance of coils (4A) and (4B) increases and the inductance of coils (4C) and (4D) decreases, as shown by the solid arrows in Figure 1, the inductance of coils (4C) and (40) increases. The current flowing through the coil (
48) and (4B). Therefore, a current flows through the coil (2) from the connection point P2 to the connection point Pl side.

On the other hand, when the current flows from the saturable reactor bridge (4) to the horizontal deflection coil (3) as shown by the broken line in Figure 1, the magnetic flux of the coils (4A) and (4B) is in the same direction as the bias magnetic flux. The inductance of this coil (4A) and (4B) decreases, and the coil (
The magnetic fluxes of the coils (4C) and (4D) decrease because they are in the opposite direction to the bias magnetic flux, and the inductance of the coils (4C) and (4D) increases.

As the inductance of coils (4A) and (4B) becomes smaller and the inductance of coils (4C) and (4D) becomes larger, as shown by the broken line arrow in Fig. The current flowing through the coil (
4C) and (4D). Therefore, a current flows through the coil (2) from the connection point P2 to the connection point P1 side.

In this way, when the current flows from the horizontal deflection coil (3) to the saturable reactor bridge (4) side, and when it flows from the saturable reactor bridge (4) to the horizontal deflection coil (3) side, the current flows in the same direction. flows. Therefore, as described above, when a sawtooth reduced current with a horizontal period flows through the horizontal deflection coil (3) as shown in FIG. On both sides, a larger current flows, that is, a correction current equivalent to a parabolic wave current. Therefore, in this example as well, the beam spot size around the screen is corrected, and the resolution is improved. Note that in FIG. 4B, the current flowing through the coil (2) decreases during the periods indicated by T1, T2, and T3, but this does not pose any problem since this is the retrace period.

According to this example, a parabolic wave current is passed through the coil (2) using the saturable reactor bridge (4) connected in series with the horizontal deflection coil (3), and an external correction circuit is not required. Therefore, it can be constructed at low cost, and the burden on the power supply can be reduced.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the present invention, a saturable reactor bridge is used to cause a parabolic wave current to flow through the coil of the correction yoke, so it can be constructed at low cost and the burden on the power supply is reduced. Can be made smaller.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram of a saturable reactor bridge, Fig. 3 is a diagram for explaining the same, and Fig. 4 is a diagram for explaining the embodiment. , FIG. 5 is a structural diagram of the cathode ray tube, and FIG. 6 is a diagram for explaining the electromagnetic four-copolar correction yoke. 11) is the electromagnetic homopolar correction yoke, (2) is its coil,
(3) is a horizontal deflection coil, (4) is a saturable reactor bridge, and (4A) to (4D) are its coils.

Claims (1)

[Claims] The cathode ray tube has a correction yoke provided at the neck portion and a saturable reactor bridge connected in series to the horizontal deflection coil, and the horizontally periodic parabolic wave current from the saturable reactor bridge is A beam spot correction device characterized in that the current flows through a coil of a correction yoke.