JPS6281891A - Color television receiver - Google Patents

Abstract

PURPOSE:To completely suppress a beam movement at any position on a screen by making a length until the front end of the side plane of a panel part at a short length side including the across part of an EMS smaller than a long length side. CONSTITUTION:An EMS2 is formed in such a way that the length of the front end of a panel part side at a short length side including the across part is set smaller than the long length side. And a receiver equipped with the EMS2 is arranged facing with south or north, and a tube axis magnetic flux is impressed. Then, the magnetic flux travels through the EMS2 as its path, and the same quantity of beam movement as usual is present at the ling length sides enclosed with the EMS2, but the quantity of beam movement increased more than usual is present at the short length sides including the across part because of no EMS2. This is cancel-corrected and a little uncorrected state is generated at any portion on the screen, and therefore, by the micro adjustment of current on a cancel coil 3, almost perfect suppression of the beam movement can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color television receiver that takes measures against unnecessary external magnetism of a color cathode ray tube.

[Conventional technology]

Measures against unnecessary external magnetism such as earth's magnetism in color cathode ray tubes used in color television receivers include magnetic shielding by installing a magnetic shield plate made of iron plate, silicon A plate, etc. on the inside and outside of the color cathode ray tube. is common. Color cathode ray tubes with diagonal dimensions of about 28 (inches) or less have reached a practical level as color television receivers by taking the above measures. As color cathode ray tubes become larger, the distance the electron beam travels increases, and beam movement problems such as color shift and raster position shift become noticeable even in the presence of an external magnetic field at the geomagnetic level.

As a countermeasure to this problem, it is conceivable to combine shielding of the external magnetic field with a method of further canceling the external magnetic field. As one example, as shown in Fig. 4, a cabinet (4) (gf
It has been devised to provide mutually opposed Helmholtz coils inside the coil (denoted as II). That is, for the purpose of canceling the three directional components of the external magnetic field (the vertical component is shown by arrow B, the north-south component is shown by arrow N/S, and the east-west direction component is shown by arrow Fi/W), each magnetic field corresponds to three directions. 3 sets of coils, one pair facing each other, that is, the coil corresponding to the E/V1 direction component (5 &)
Coils (aa) and (6b) corresponding to e (5b), N/s direction components (the ones corresponding to nv are omitted for convenience of drawing) are provided, and a direct current is passed according to the strength of the external magnetic field. Generates a canceling magnetic field, color brown g
(1) This is a method that attempts to cancel out the external magnetic field that is trying to be applied.

However, this method does not allow cancellation coils (5-), (5b
), (6&), and (+31=) become large in size and require a large number of ampere turns (AT) for cancellation.

The reason why a large number of ATs is required is that the canceling coils (5a), (5b), (6&), (6b) are arranged at a distance from the color cathode ray tube (1).
This is because the efficiency is extremely low.

In order to improve the cancellation efficiency, there is an example in which a cancellation coil (3a) or a mechanism (3) is arranged close to a color cathode ray tube (1), as shown in FIGS. 5 and 6.

What is shown in Figure 5 is an internal magnetic shield plate (not shown) (
This is an example in which an N/S canceling coil (3,) is installed in a color cathode ray tube (1) with a built-in magnetic field (hereinafter abbreviated as MS) to cancel the magnetic field in the tube axis direction (N/la field in Fig. 4). be. If necessary, a cancellation coil for the B magnetic field and a cancellation coil for the W magnetic field are disposed close to the color cathode ray tube (1), but these are omitted here.

Although this method is more efficient than the method shown in FIG. 4, the efficiency is still not sufficient because the color cathode ray tube (1) has a built-in M3.

This is an example in which an N/S cancellation coil (3b) is arranged inside an external magnetic shield plate (2) (hereinafter abbreviated as 1M13) provided outside the Monoke color cathode ray tube (1) shown in FIG. Again, due to the drawing, By and H
The 7W cancellation coil is omitted. This EM
S (2) is a color CRT with 1MS or IMS
Although it can be used for one color cathode ray tube and a combination of O-zo,
Since the canceling coil (3b) is covered by χM S (21), the canceling magnetic field B K M El (2) can be efficiently applied to the color cathode ray tube (1) as a magnetic core. Therefore, as shown in FIG. It is possible to improve the cancellation efficiency compared to the above method.

The method shown in Figure 6 has better cancellation efficiency than the method shown in Figure 5, but it is difficult to match the magnetic field distribution of the generated canceling magnetic field with the external magnetic field distribution such as the earth's magnetism, and therefore the color It is difficult to completely eliminate beam movement of the cathode ray tube (1) anywhere on the screen. Furthermore, to explain this, the beam position on the fluorescent surface of the color cathode ray tube (1) deviates from its original position due to the influence of external magnetic fields such as earth's magnetism, but by passing an appropriate current through the canceling coil (3b), It has been found that it is difficult to generate a canceling magnetic field to effectively suppress beam movement at any position on the screen. This drawback can be said to be the same in the less efficient one shown in FIG. 4 and the one shown in FIG.

FIG. 7 shows a magnetic canceling coil wound both inside and outside the EMS.

In this method, the cancellation coil is placed inside the EMS at the coil position corresponding to the part where the cancellation correction is desired to be made stronger, and the cancellation correction is made weaker. At the coil position corresponding to the desired portion, by arranging the cancellation fill outside the IcMS, the cancellation magnetic field distribution becomes a desired shape.

Figure 7 shows only the N/S cancellation coil (3) for canceling the magnetic field in the tube axis direction, but the concept is the same for the cancellation coils for Bma and Ili/W magnetic fields. Explanation will be omitted. E M
A notch (9) is formed on the long side of the outer peripheral wall of S (2). N/S cancel fill (3) ke E u
It is wound across both the inside and outside of E M S (2) with the notch (9) of S (2) as a boundary. In detail, the coil portions (31a) #(3) correspond to both sides (short side) and corners of the screen of the color cathode ray tube (1).
1b) is arranged outside of E M 5 (2), and the coil parts (32a) and (32
b) It is placed inside the I M S (2).

As is well known, when a color cathode ray tube (1) is installed facing north (N direction) in a place where the earth's magnetic field exists, the fluorophore beam on the screen undergoes rotational movement as shown by the arrow in Figure 2, causing color shift. or raster rotation. The extent of this beam movement depends on the deflection angle, inch size, electron gun structure, etc. of the color cathode ray tube (1), but the amount of movement also differs depending on the location on the screen. As a specific example of beam movement,
If the amount of movement of the fluorescent surface (the amount of mislanding) is plotted in the first quadrant of the screen as represented by the points T, TTR, TR, TRR, and R in Figure 2, the curve (, ) in Figure 3 will be obtained. .

In this example, 3 inches (inches) 11
Earth's magnetism of 0.3 Gauss is applied to a color cathode ray tube of 0° stripe fluorescent surface type in the tube axis direction, and the amount of horizontal beam movement after demagnetization is plotted in μm.

In the same figure, curves (b-1) and (b-2) respectively indicate the cancellation correction (2) and the correction formula corresponding to the method shown in FIG. In other words, if a current is applied to the cancellation coil (31) shown in FIG. 6 so that the beam movement at the screen corner point TR becomes zero, at the screen corner T and TTR point,
As is clear from the curve (b-1), there is a significant under-correction, and at the TRR point, as is clear from the curve (b-2), there is a significant over-correction. However, in this case, the cancellation correction - song! It should be noted that the polarity of curve (b-4) is opposite (minus) to that of curve (a).

On the other hand, in the method shown in Fig. 7, the cancellation correction value is the curve (0-1), and the cancellation correction formula is the curve (c-2
), and it can be seen that the number of correction formulas is significantly reduced compared to the curve (b-2) of other methods. The reason for this is as follows.

In other words, if EMS+21 is the magnetic core and the coil (3) is on the inside, that is, on the color cathode ray tube (1) side, the EM
A large canceling magnetic field is generated inside S (2), and when the coil (3) is placed outside, a large canceling magnetic field is generated outside E M S (2). In other words, KM3
This is because the canceling magnetic field is not significantly applied to the color cathode ray tube (1) at a considerable location where the coil (3) is placed outside of the color cathode ray tube (1).

[Problem that the invention seeks to solve]

However, even with the method shown in Figure 7, TTR
An unbalanced state remains with under-correction at points and over-correction at TR and TRR points, and this is not the best method for effectively suppressing beam movement at any position on the screen.

This invention has good cancellation efficiency against external magnetic fields,
It is an object of the present invention to provide a color television receiver in which beam movement can be almost completely suppressed at any position on the screen.

[Means for solving problems]

In the color television receiver according to this invention,
ICMS is used, and the length to the front end of the side surface of the panel part on the short side including the diagonal part of [111M] is made shorter than that on the long side.

[Effect]

In this invention, in response to the beam movement machine using an external magnetic field at each position on the screen of a color cathode ray tube, the shape of the screen is shortened by shortening the EMS at the position corresponding to the portion where cancellation correction causes overcorrection. At all positions, the beam movement can be almost completely suppressed by leaving the cancellation correction in an uncorrected state and adjusting the slight current to the cancellation coil.

[Embodiments of the invention]

FIG. 1 shows an example of a color television receiver according to the present invention. Here, only the N/S cancellation coil (3) for canceling the magnetic field in the tube axis direction is shown, but the concept of the cancellation coil for the B and E/W magnetic fields is the same, so the explanation will be Omitted.

In Figure 3, by making the amount of beam movement at the points TR and TRR on the curve (&) larger than the amount of beam movement on the curve (o-1), the beam movement at the points TR and TRR on the curve (o-2) is can be the uncorrected direction. In other words, as shown in FIG. 1, Ei M S (
21 shape. When a color television receiver using the above EM S (2) is installed facing south or north and a tube axis magnetic field is applied, the magnetic flux will be EM S
(2) flows as a magnetic path. Therefore, EMS(2)
On the long side surrounded by , the beam movement is the same as in the conventional case, and the values are shown at the T and TTR points of the curve (&) in FIG. 3. However, the short side including the diagonal part is E M S (2)
Since there is no beam movement, the beam movement is larger than that of the conventional 3MS.

The value is TR and TR1 point shown in curve (b) of FIG. 3. When this is canceled and corrected, the correction i& is a curve (o −1), so the cancellation correction formula is a curve (
o −3). In other words, the TR and '1' RR points can be left uncorrected. Therefore, since there is a slight uncorrected state at any position on the screen, it is possible to almost completely suppress beam movement by just finely adjusting the current flowing to the canceling coil (3).

Although this example has been explained using a color cathode ray tube (1) having a striped phosphor surface, the present invention can also be applied to a color cathode ray tube having a dot structure phosphor surface.

When the external unnecessary magnetic field is an alternating magnetic field (AC), this is achieved by applying an AC canceling current corresponding to the alternating magnetic field (AC).

〔Effect of the invention〕

As explained above, according to the present invention, the length of the front end of the panel portion on the short side including the diagonal portion is shorter than that on the long side.
By using the MS in combination with a canceling coil wound inside and outside the EMS, it becomes easier to obtain the desired canceling magnetic field distribution, thus achieving a near-ideal magnetic canceling effect in an efficient state. is obtained.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing an example of magnetic canceling means of a color television receiver according to the present invention, FIG. 2 is a diagram showing an example of beam movement due to the influence of a magnetic field in the tube axis direction of a color cathode ray tube, and FIG. 4 is a perspective view showing the conventional magnetism canceling means, and FIGS. FIG. 3 is an explanatory diagram of magnetic canceling means. In the figure, (IHt color cathode ray tube, t2) is a magnetic shield plate (Ei M S), and (3) is a magnetic canceling coil. In addition, in the figures, the same reference numerals indicate parts corresponding to the same mechanism.

Claims (1)

[Claims] A magnetic shield plate configured to integrally surround the funnel part of the color cathode ray tube to the front of the side surface of the panel part, and a magnetic cancellation coil wound both inside and outside of the magnetic shield plate. In the color television receiver installed in combination with A color television receiver characterized by being shorter.