JPH0656742B2 - Color picture tube device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a color picture tube device having three electron beams.

[Technical background of the invention and its problems]

Most of the ordinary color picture tubes have three electron guns that are arranged in-line in the horizontal direction.
The electron gun, the shadow mask, and the screen are optimally arranged relative to each other so that the electron beam selectively strikes.

FIG. 7 shows a schematic structure of a conventional color picture tube. 7th
In the figure, the color picture tube first has an insulator-made envelope composed of a panel (1), a funnel (2) and a neck (3) in order to maintain a high vacuum inside. The front surface of the panel (1) is a screen that displays a television image and the like in a roughly rectangular shape.

The neck (3) includes an electron gun (4) for generating an electron beam therein. The funnel (2) is located between the neck (3) and the panel (1).
It is a department.

Such a color picture tube includes three electron guns (4R), (4G), and (4B) corresponding to the three primary colors of R, G, and B in the network (3), and the three electron guns (4R), (4R), 4G) and (4B) are arranged horizontally inline. Although not shown, each electron gun includes a heater, a cathode, a control electrode, a focusing electrode, a high voltage electrode, and the like. The amount of thermoelectrons emitted from the cathode heated by the heater is determined by the control electrode to reach the screen, and the electron lens formed between the focusing electrode and the high-voltage electrode makes it optimal on the screen. Receive a focusing action.

In Fig. 7, the trajectories of this electron beam are shown as (5R), (5G), and (5B).

The three electron beams (5R), (5G), and (5B) are further set so as to be concentrated at one point in the central portion of the screen by electrostatic and / or magnetic action. Further, a shadow mask (6) having a large number of regularly arranged micro apertures is held at a predetermined distance from the inner surface of the panel (1) which is a screen.

3 Electron beams (5R), (5G), (5B) are used for this shadow mask (6)
The positions where the respective screens can be struck are selected by means of, and the R, G, and B three-color fluorescent light that has been formed by coating in advance corresponding to the struck positions of the electron beams (5R), (5G), and (5B). Accurately cause the body to emit light (not shown).

The deflection yoke (7) that scans the electron beams (5R), (5G), and (5B) over the entire surface of the roughly rectangular display screen is surrounded by the funnel (2) and the neck (3) so as to surround them. Is located in.

The deflection yoke (7) is usually composed of two orthogonal coil groups. The first deflection coil most commonly consists of a pair of upper and lower saddle coils (7a) and generates a horizontal deflection magnetic field. The second deflection coil is generally a toroidal coil (7b) that is toroidally wound around an annular magnetic core, and generates a vertical deflection magnetic field.

Mostly self-concentrated color picture tubes,
This is a three electron beam emitted from an in-line array electron gun by controlling the deflection magnetic field generated by the deflection yoke (7).
This method concentrates (5R), (5G), and (5B) on the entire rectangular screen.

In this system, the horizontal deflection magnetic field must be of pink type and the vertical deflection magnetic field must be of barrel type.

Further, as the most effective means for achieving a practically sufficient concentration error, there is a magnetic field control element made of a magnetic material of high magnetic susceptibility as shown in FIGS. 8 (a) and 8 (b). That is,
As proposed in Japanese Patent Publication No. 58-45135 and Japanese Patent Publication No. 51-44046, generally, a deflection yoke (7) and an electron gun (3R),
The deflection yoke (7) is placed at an appropriate position between (3G) and (3B).
It has the effect of acting on the leaking magnetic field of and making the raster sizes drawn by the central electron beam (5G) and the electron beams on both sides (5R) and (5B) match. Also, in Japanese Examined Patent Publication No. 58-7017, No. 8 of the same gazette is used.
As shown in the figure, by arranging two types of magnetic shield elements so that they are not on the same plane in the tube axis direction, the degree of freedom in correcting coma aberrations in both the horizontal and vertical axes is increased, Proposals have been made that the coma aberrations on both the horizontal and vertical axes can be set to predetermined values.

However, the color picture tube using the above-mentioned conventional magnetic control element has the following drawbacks. As described above, the usual color picture tube is mainly of the self-focusing type in which the three electron beams of R, G and B coincide on the display screen. This is to obtain the concentration of an electron beam by utilizing the aberration component of the deflection magnetic field itself. The magnetic field needs to have a pink deflection type horizontal deflection magnetic field and a barrel type vertical deflection magnetic field. Furthermore, the magnetic field control element installed at the tip of the electron gun enclosed inside the neck (3) acts on the leaking magnetic field of the deflection yoke to make the central beam (5G) coincide with both side beams (5R) and (5B). .

However, the concentration of the central beam (5G) and both side beams (5R) and (5B) is greatly deteriorated at the corners of the screen.

FIG. 9 is a schematic diagram showing a state where the central beam (5G) and the side beams (5R) and (5B) do not match. In FIG. 9, the solid line represents both side beams and the broken line represents the central beam. The above-mentioned magnetic field control element is usually designed by paying attention to the points (a) and (b) so that the central beam coincides with both side beams.

As shown in the figure, however, the horizontal line on the screen moves away from the V-axis and the central beam hangs down with respect to both side beams as it approaches the screen corner, which significantly increases the convergence error at the screen corner, resulting in image quality Cause deterioration. The sagging phenomenon, which is mainly due to such corners, is an unacceptable quality for high-resolution character display. Further, this phenomenon becomes more remarkable as the screen becomes larger and the deflection angle increases. Also V
At the midpoint a'on the axis, the central beam is shifted outward from both side beams, and the convergence quality is deteriorated even near the center of the screen.

For example, in the shape and arrangement of the magnetic shield element as shown in FIG. 8 of Japanese Patent Publication No. 58-7017, focusing on the vertical axis, the first magnetic shield element on the cathode side causes the central beam with respect to the central beam. Acts to increase the deflection sensitivity, while the second magnetic shielding element acts to reduce the deflection sensitivity for the central beam. Even in the color picture tube having such a structure, a phenomenon in which the central beam hangs down with respect to both side beams remarkably occurs as it approaches the screen corner.

[Object of the Invention]

The present invention has been made in view of the above points, and an object thereof is to improve the mismatch between the rasters of both side beams and the central beam raster to obtain good image quality and good high-resolution character quality.

[Outline of Invention]

The present invention has a first magnetic field control element and a second magnetic field control element, which are located between a cathode, which is an electron beam generation source, and a deflection yoke, and are separated from each other by a predetermined distance in the electron beam traveling direction. Is located on the deflection yoke side and has the effect of making the central beam raster relatively large in the direction perpendicular to the plane defined by at least three beams, and the second magnetic field control element is located on the cathode side. A color image which has an effect of relatively enlarging both side beam rasters and which makes a central beam raster and both side beam rasters coincide with each other by cooperation of a first magnetic field control element and a second magnetic field control element It is a tube and can obtain good convergence characteristics that cannot be obtained by the conventional color picture tube.

Example of Invention

The present invention will be described in detail below with reference to the drawings. Since the overall structure of the color picture tube device to which the present invention is applied is the same as that shown in FIG. 7, only the essential parts of the present invention will be described below.

FIG. 1 shows a first embodiment according to the present invention.

The annular magnetic field control elements (10R) and (10B) made of a high-permeability magnetic material forming the magnetic field control element of FIG. 1 are arranged so as to surround the passages of both side beams (R). The magnetic field control element (10G) that constitutes the second magnetic field control element group is an annular magnetic field control element that is also made of a high magnetic permeability magnetic material that surrounds the passage of the central beam (G).

The first magnetic field control element and the second magnetic field control element are separated from each other by a predetermined distance (l) in the beam traveling direction, the first magnetic field control element is on the side of the deflection yoke, and the second magnetic field control element is the cathode (11 )
To place. (12) represents the leakage magnetic field lines of the deflection magnetic field generated by the deflection yoke. In FIG. 1, the electron gun electrodes other than the cathode are not shown. The magnetic field control elements (10R), (10B) and (10G) act on the leaking magnetic field lines (12) to control the deflection sensitivity of each electron beam.
That is, each of the high magnetic permeability annular elements (10) R), (10B), and (10G) has a common effect of concentrating a leaking magnetic field on the element itself and at the same time shielding the inside thereof. Therefore, when passing through the interior of the clearing element, the beam has reduced deflection sensitivity. Therefore, the first magnetic field control element increases the deflection sensitivity of the central beam (G) as shown in FIG. 2 (a), and conversely the second magnetic field control element as shown in FIG. 2 (b). The deflection sensitivity of the central beam (G) is reduced. The above-mentioned increase / decrease in the deflection sensitivity corresponds to the increase / decrease in the size of the central beam raster with respect to both side beam rasters as a result on the screen.

In this way, the first magnetic field control element increases the vertical raster size of the central beam, and the second magnetic field control element reduces the vertical raster size of the central beam. If the size of the side beam is matched with the vertical size of the raster, the phenomenon that the central beam raster hangs down at the corners of the screen as shown in FIG. 9 can be improved.

FIG. 3 (a) shows the deviation of the raster size when the magnetic field control element is not used. It is shown by a solid line and the central beam raster is shown by a broken line with reference to both side beam rasters. That is, in the self-concentrating deflection yoke, the vertical raster size of the central beam is smaller than that of both side beams. This value is totally unacceptable in practice.

FIG. 3 (b) shows the raster size when only the first magnetic field control element according to the present invention is used. The central beam raster shown by the alternate long and short dash line is larger than both side beam rasters and quantitative. The vertical axis is larger than the screen corner.

FIG. 3 (c) shows the raster size when only the second magnetic field control element according to the present invention is used. The center beam raster shown by the chain double-dashed line is much smaller than the rasters of both side beams and is located at the corner. The vertical axis is smaller by comparison. Here, the difference between the raster sizes on the vertical axis (V axis) is A, that at the corner (D axis) is B, and the suffix when there is no magnetic field control element is "0", that of the first and second magnetic field control elements. The cases are represented by "1" and "2", respectively.

The raster correction amounts by the first magnetic field control element are (A ₁ + A ₀ ) and (B ₁ + B ₀ ) on the V axis and the D axis, and those of the second magnetic field control element are (A ₂ + A ₀ ) and (B 2 _2- B ₀ ). The present inventors have made detailed experimental studies on the ratio of the correction amounts of the V axis and the D axis.

As a result, 1> k ₁ > k ₂ > 0 I knew it was. That is, the ratio of the V axis to the D axis of the correction amount by the first magnetic field control element group is larger than that of the second magnetic field control element group, and both are in the middle of 1 to 0.

Generally speaking, this is V near the deflection yoke.
Although the correction amounts of the axis and the D axis are close to each other, the correction amount of the D axis becomes small as the distance from the deflection yoke increases, which means that the correction is performed only on the V axis. Further, these things are deeply related to the position of the magnetic field control element regardless of the shape or the like.

As described above, it is specifically shown that the raster sizes are uniformly matched from the V axis to the D axis of the screen.

Usually A ₀ and B ₀ are almost equal.

A ₀ = B ₀ (3) The raster sizes match on the V axis.

A ₁ = A ₂ −A ₀ …… (4) The raster size difference at the screen corner is calculated by using the formulas (1) to (4). Δ ＝ B ₁ − (B ₂ −B ₀ ) ＝ (k ₁ − k ₂ ) A _2- (1-k ₂ ) A ₀ ...... (5) Therefore, Then, the raster will match at the corner.

Where A ₀ is a value determined by the bidirectional yoke, k ₁ and
k ₂ is a value determined by the positions where the first and second magnetic field control elements are arranged, and A ₂ is uniquely determined.

Therefore, the necessary correction amount of the magnetic field control element of FIG. The necessary correction amount of the second magnetic field control element is It is clear that

Next, a specific example in which the present invention is applied to a 25-inch type 110-degree deflection color picture tube is shown. A ₀ is 4.0 mm. The positions of the first and second magnetic field control elements are arranged from the deflection yoke end about
20mm and about 40mm. The distance Sg between the beams is 6.6 mm. At this time, k ₁ and k ₂ were experimentally determined to be k ₁ = 0.7 k ₂ = 0.3.

Therefore, by using the equations (6) and (7), the proper correction amounts of the first and second magnetic field control elements are 7.0 mm and 3.0 mm, respectively. The characteristics of the above-described color picture tube implemented based on the above are 0 to 0.8 when the center beam raster sags at the corners when the rasters on the V-axis are matched. It was possible to reduce it to about 0.2 mm. Here, the first magnetic field control element and the second magnetic field control element
The change of the position k of the magnetic field control element and the ratio k of the raster correction amounts of the V axis and the D axis is shown in FIG. 4, and the second magnetic field control is performed with respect to the positions C ₁ and C _{2 of} the first and second magnetic field control elements. When the position of the element is point A (l≈10), k ₂ ′ = 0.5, and the necessary correction amounts are 10.0 mm for the first magnetic field control element and 6.0 mm for the second magnetic field control element.

If the two approach each other in this way, the required correction amount of both rapidly increases, which is not preferable.

On the contrary, when the second magnetic field control element is at the point B (l≈4
0), k ₂ ″ = 0.1, and the necessary correction amounts for the first and second magnetic field control elements are 6.0 mm and 2.0 mm, respectively.

In this case, the amount of correction is relatively small, but the magnetic field existing in the vicinity of the second magnetic field control element is weak, and the correction itself becomes difficult. Therefore, the first and second magnetic field control element spacing l is standardized by the beam spacing Sg, Preferably It is good to

Next, another embodiment of the present invention will be described.

Although the annular element is shown in FIG. 1 showing the first embodiment, the magnetic field control element may be cylindrical or not necessarily circular.

As the first magnetic field control element, the shapes shown in FIGS. 8 (a) and 8 (b) can also be used. Basically, the shape of the taper for improving the sensitivity of the central beam raster accompanying the vertical deflection is used. If it is an element, the shape and the like can be arbitrarily selected. or,
The second magnetic field control element can be arbitrarily selected as long as it is of a type that reduces the sensitivity of the central beam raster.

FIG. 5 and FIG. 6 show other combinations of the magnetic field control elements described above.

〔The invention's effect〕

As is apparent from the above description, in the color picture tube device having the first and second magnetic field control elements according to the present invention, the central beam rasters are inconsistent, especially in the corners, which has deteriorated the image quality remarkably than before. Was able to be greatly improved. Also, we were able to improve the disagreement in the middle part of the screen.

As described above, according to the present invention, it is possible to significantly improve the convergence characteristics that were conventionally unachievable, and the effects such as the performance improvement of a large wide-angle tube and the resolution improvement of a charactor display tube are very effective. It has a great industrial value and is extremely large.

[Brief description of drawings]

FIG. 1 is a cutaway perspective view of an essential part showing an embodiment of first and second magnetic field control elements according to the present invention, FIGS. 2 (a) and 2 (b).
Is a partial plan view for explaining the operation of the first and second magnetic field control elements in FIG. 1, and FIGS. 3 (a) to 3 (c) are for explaining raster size correction on the screen. Fig. 4 is a characteristic diagram for explaining the ratio of the raster correction amounts of the V axis and the D axis to the positions of the first and second magnetic field control elements, and Figs. 5 and 6 are other magnetic field controls. FIG. 7 is a schematic view showing an example of a combination of elements, FIG. 7 is a sectional view showing a schematic configuration of a color picture tube, and FIGS. 8 (a) and 8 (b) are partial plane views showing an example of a conventional magnetic field control element. FIG. 9 and FIG. 9 are schematic diagrams for explaining the disagreement of the central rasters according to the conventional technique. (1) …… panel, (2) …… funnel (3) …… net, (4) …… electron gun (6) …… shallow mask, (7) …… deflecting yoke (10R), (10B), ( 10G) ... Magnetic field control element

Claims (2)

[Claims] 1. A picture tube comprising an envelope comprising a neck portion, a front panel portion, and a funnel portion intermediate between the neck portion and the panel portion, and a center beam and both side beams in the neck portion of the picture tube. The electron gun assembly for generating an electron beam of three in-line arrangements, and the deflection yoke arranged around the funnel portion and the neck portion, the deflection yoke being generated by the electron gun assembly.
The size of the raster drawn by the three electron beams, which is made up of the first and second deflection coils that respectively deflect in the first deflection direction determined by the plane containing the electron beam and in the second deflection direction perpendicular to the plane containing the three electron beams. Has a magnetic field control element made of a high-permeability magnetic member in the neck portion so as to substantially coincide with each other. The magnetic field control element controls the size of the raster of the center beam on both sides in at least the second deflection direction. Contrary to the first magnetic field control element for increasing the convex shape relative to the beam raster, the second magnetic field control element for decreasing the size of the center beam raster to the concave shape relative to the two side beam rasters. Between the deflection coil of the deflection yoke and the cathode of the electron beam generation source of the electron gun, including a magnetic field control element, the first magnetic field control element and the second magnetic field control element are arranged in this order from the deflection coil side. Arranged in a direction, the first and second magnetic field control element mutual tube axes interval l is the electron beam spacing S
A color picture tube device having a relationship of 6 ≧ l / Sg ≧ 1 with g. 2. The first magnetic field control element is made of a magnetic material member having a structure that roughly surrounds a side beam, and the second magnetic field control element is made of a magnetic material member that is roughly structured to surround a center beam. The color picture tube device according to claim 1, wherein