JPS6258552A - Deflection yoke - Google Patents

Abstract

PURPOSE:To minimize the shape of auxiliary coils and thereby improve focusing characteristics by providing a pair of auxiliary coils corresponding respectively to each of a pair of main coils for horizontal deflection and making horizontal periodic sawtooth current flow through said auxiliary coils. CONSTITUTION:A deflection yoke for an in-line type color picture tube is formed, a pair of main coils for horizontal deflection of which being provided respectively with a pair of auxiliary coils. The main coil 1 for horizontal deflection being connected with the auxiliary coils 2, 3 in series, the main coil 4 with the auxiliary coils 5, 6 in series, these coils are connected in parallel and have horizontal-periodic sawtooth current IH made flow through there. And the horizontal magnetic field distribution is made so that the change rate of the magnetic field strength is made small in the region apart small distance from the axis and great in the region apart large distance from the axis. Therefore, it is possible to make the magnetic field approach to a uniform magnetic field by small-shaped and besides low cost auxiliary coils and to improve focusing characteristics at the periphery of a picture.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a deflection yoke used in an in-line color picture tube.

[Prior Art] Generally, in an in-line color picture tube, three electron guns (11) of red, green, and blue are used, as shown in FIG.
The electron beams emitted from (12) and (13) are electromagnetically deflected by the magnetic field of the deflection yoke (14), and draw a raster on the screen.

Now, when there is no deflection, if the concentration point of each electron beam is moved to the center point (+5a) of the shadow mask surface (15), the concentration points of the three beams at the periphery will form a locus (16) shown by the dotted line. do. Therefore, this concentration point locus (16
) to match the shadow mask surface (15), the deflection magnetic field distribution is made non-uniform, for example, the horizontal magnetic field is often a bottle cushion magnetic field, and the vertical magnetic field is often a barrel magnetic field.

Now, when focusing on the horizontal magnetic field, the relationship between the distance from the tube axis (#wheelbase distance #) and the strength of the magnetic field in the bottle cushion magnetic field is shown in FIG.

However, in order to completely match the curvature of the concentration point trajectory (16) of the three beams due to changes in the strength of the magnetic field and the curvature of the shadow mask surface (15), it is necessary to simply change the horizontal magnetic field to a bottle cushion magnetic field. For example, as shown in Japanese Unexamined Patent Publication No. 52-28220,
A deflection yoke including a pair of auxiliary coils A that utilizes the excitation effect of a horizontal deflection magnetic field has been proposed.

An example of such a deflection yoke is shown in FIG. 7(a).
(b) and the magnetic field distribution are shown in the 'iBB diagram. According to this, a back electromotive force is generated in the auxiliary coil (18) due to the magnetic field (9) caused by the horizontal deflection coil (7),
Based on this, an auxiliary magnetic field (8) is generated. This auxiliary magnetic field (8) is a magnetic field (
9), and the magnetic field (9) is weakened outside the auxiliary coil (1 day).
), the magnetic field distribution within the deflection yoke becomes as shown in characteristic (10) in FIG. - In other words, the magnetic field distribution has a small rate of change in magnetic field strength near the center of the screen, and a wide rate of change in magnetic field strength near the periphery of the screen.

“Problems to be Solved by the Invention” The conventional deflection yoke is configured as described above, and uses the change in magnetic field caused by the horizontal deflection coil (7) as a means for generating a magnetic field in the auxiliary coil (18). However, in order to make sufficient correction, an auxiliary coil (18) with a large number of turns was required, and there were problems such as the shape of the deflection yoke (14) becoming too sharp. In general, the water deflection coil magnetic field must be a bottle cushion magnetic field, and the focus characteristics have not been improved much due to the influence of such a non-uniform magnetic field.

This invention was made in order to solve the problems mentioned in (-), and uses an auxiliary coil with a small number of turns to easily provide the necessary magnetic field distribution and to form a nearly uniform magnetic field. The objective is to provide a deflection yoke that can prevent deterioration of focus characteristics.

[Means for Solving the Problems] The deflection yoke according to the present invention is provided with a pair of auxiliary coils corresponding to each of the pair of seven coils for deflection, and these auxiliary coils are provided with a horizontal periodic sawtooth shape. A current is passed to form an auxiliary magnetic field, and this auxiliary magnetic field weakens the magnetic field of the main coil for water moth deflection at locations where the off-axis distance is small, and weakens the magnetic field of the main horizontal deflection coil at locations where the off-axis distance is large. This was done so that it would be strengthened.

[Function] In the deflection yoke of the present invention, the magnetic field generated by the horizontally periodic sawtooth current flowing through the pair of auxiliary coils adjusts the magnetic field created by the main horizontal deflection coil to an optimal distribution, thereby increasing the number of turns of the auxiliary coil. Good convergence can be obtained across the entire screen without having to increase the amount of convergence. Further, since the magnetic field of the horizontal deflection main coil does not require an extreme B-cushion magnetic field, good focusing characteristics can be obtained around one screen.

['y example] Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows one of a pair of horizontal deflection coils, where (1) is the main coil for horizontal deflection, (2)
, (3) indicates the auxiliary coil, (la), (lb)
.

(2a), (2b), (3a), and (3b) show the line drawing ends of the respective coils.

FIG. 2 shows these connections. That is, (
By connecting 1b) and (2a), and (2b) and (3a), respectively, the main deflection coil (1) and the auxiliary coils (2) and (3) are connected in series.

In addition, a main coil (1) and an auxiliary coil (2) for deflecting water moss are also included.
), (3), the other water feather deflection main coil (4) and auxiliary coil (5), (13)
are connected in series, and these two row 1a coil bodies are connected in parallel. A pair of such main coils (1), (4) and auxiliary coils (2) for Kihira deflection,
(3).

(5) and (8) constitute a water deflection coil (7), and a horizontal periodic sawtooth current IH flows through these coils.

In the horizontal deflection coil (7) configured as above, if the winding direction of each coil is the direction shown by the arrow in FIG. 3, then as shown in FIG. 4, the auxiliary coil (2), (
The auxiliary magnetic field (8) formed by the auxiliary coil (
2) and (3), in the direction of strengthening the magnetic field (9) of the water moth deflection coil (1), and between the auxiliary coils (2) and (3) (between PI and P2). In each case, the strength of the magnetic field changes in the direction of weakening the magnetic field (3), and the FI-continuous horizontal magnetic field produced by these coils has a distribution shown by characteristic (10) in FIG.

Therefore, the magnetic field caused by the horizontal deflection main coil (1) is a very small bottle cushion magnetic field (9), and the auxiliary coils (2) and (3) have a uniform auxiliary magnetic field (8).
By doing so, it is possible to obtain a horizontal magnetic field distribution in which the rate of change in the magnetic field strength is small where the off-axis distance is small, and the rate of change in the magnetic field strength is large where the off-axis distance is large.

In addition, since the desired magnetic field can be obtained without making the magnetic field (8) generated by the horizontal deflection main coil (1) into a strong bottle cushion magnetic field, the focusing characteristics near the periphery of the screen will not deteriorate. Good focus characteristics can be obtained.

In addition, in the embodiment described above, the auxiliary coils (2), (3
) is shown connected in series with the main coil for horizontal deflection (1), but it is also possible to connect the main coil for horizontal deflection (1) and the auxiliary coils (2), (3) in series. may be made independent, and a horizontal periodic sawtooth current may be caused to flow through the auxiliary coils (2) and (3) using a separate circuit.

[Effects of the Invention] As described above, according to the present invention, the shape of the auxiliary coil can be made small and A general horizontal deflection magnetic field can be obtained at low cost, and since this magnetic field is close to a uniform magnetic field, it is possible to maintain good focus characteristics around the screen.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of a water deflection coil according to an embodiment of the present invention, FIG. 282 is a circuit diagram showing the connection relationship of the horizontal deflection coil of FIG. 1, and FIG. A diagram showing the winding direction of the coil, Figure 4 is a magnetic field distribution diagram due to the horizontal deflection coil in Figure 1, Figure 5 is a cross-sectional view of an in-line color picture tube, and Figure 6 is a magnetic field distribution diagram due to a conventional bottle cushion magnetic field. 7(a) is a front sectional view showing another conventional deflection yoke, FIG. 7(b) is a side sectional view thereof, and FIG. 8 is the deflection yoke of FIGS. 7(a) and (b). It is a horizontal magnetic field distribution diagram according to. (1), (4)...Main coil for water moth deflection, (2
) (3) , (5) , (13)... Auxiliary coil, (8)... Magnetic field distribution due to the auxiliary coil, (9)
...Magnetic field distribution due to the main coil for horizontal deflection, (10)
・Horizontal magnetic field distribution, IH...Horizontal periodic sawtooth 'ilf
Flow, X... Off-axis distance. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A pair of auxiliary coils is provided corresponding to each of the pair of main coils for horizontal deflection, and a horizontal periodic sawtooth current is passed through these auxiliary coils to form an auxiliary magnetic field. A deflection yoke characterized in that the magnetic field of the horizontal deflection main coil is weakened at locations where the axial distance is small, and the magnetic field of the horizontal deflection main coil is strengthened at locations where the off-axis distance is large.