ITT IDEAL COLOR 3794 HIFI CHASSIS COMPACT CHASSIS 80 DST 5861 70 22 CRT TUBE ITT (SEL) A67-701X

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CRT TUBE ITT (SEL) A67-701X

CRT Socket

This is a S.P.I. (Super Precision In Line) CRT

In-line gun system for a color picture tube:
Super Precision In-Line ITT SEL.
In a color picture tube with an in-line gun system elliptic beam-spot distortion caused by the deflection field is compensated for by pairs of plates in at least one focus electrode. The plates project into the apertures for the electron beams and are located at a distance from the bottom of the focus electrode.

What is claimed is: 1. A color picture tube, comprising:
a screen;
a funnel;
a neck;
a deflection system mounted on said neck at the transition of said neck to said funnel and which contains an inline gun system comprising cathodes and grid and focus electrodes, said focus electrodes having separate apertures each with a continuous edge for guiding electron beams to said screen, at least one of said focus electrodes having plates attached thereto which are located on both sides of the electron beams and are disposed on the screen side of said at least one said focus electrodes; said plates having curved portions which project into said apertures and are arranged in a spaced relationship from the screen side of the aperture of the respective focus electrode; and
one of the grid electrodes contains a slit diaphragm.
2. A color picture tube as claimed in claim 1, wherein:
vertices of said curved portions of said plates for the outer electron beams are located beside the center lines of said apertures for these electron beams in the focus electrode.
3. A color picture tube as claimed in claim 1, wherein:
the distances (w) between opposite ones of said plates
are different for the different electron beams.
4. A color picture tube as claimed in claim 1, wherein:
the distances between said plates and the bottom of the respective focus electrode differ for the individual electron beams.

Description:

BACKGROUND OF THE INVENTION
The present invention relates to a color picture tube.
U.S. Pat. No. 4,086,513 discloses a color picture tube with an in-line gun system in which parallel plates are attached to a focus electrode on both sides of the beam plane. This parallel pair of plates is directed towards the screen and serves to compensate the elliptic distortion of the beam spots by the deflection field, such distorted beam spots reducing the sharpness of the image reproduced. The pair of plates is attached to the focus electrode nearest to the screen. Alternatively, plates can be attached to a focus electrode near the first-mentioned focus electrode on both sides of the beams directed towards the last focus electrode. These plates are mounted at an angular distance of 90 degrees from the first-mentioned parallel pair of plates.
SUMMARY OF THE INVENTION
It is one object of the invention to provide a color picture tube with an in-line gun system causing an improvement in the compensation of the distortion of beam spots.
BRIEF DESCRIPTION OF THE DRAWING
The embodiments of the invention will now be explained with reference to the accompanying drawings, in which:
FIG. 1 is a side view of a color picture tube;
FIG. 2 is a side view of an in-line gun system;
FIG. 3 is a top view of a focus electrode;
FIG. 4 is a section through the focus electrode of FIG. 3 along line IV--IV.
DETAILED DESCRIPTION
FIG. 1 shows a color picture 10 tube comprising a screen 11, a funnel 12, and a neck 13. In the funnel 13, an in-line gun system 14 (drawn in broken lines) is located producing three electron beams 1, 2, 3, which are swept across the screen 11 (1', 2', 3'). A magnetic deflection system 15 is located at the transition from the neck 13 to the funnel 12.







FIG. 2 is a side view of the in-line gun system 14. It has a molded glass disk 20 with sealed in contact pins 21. The contact pins 21 are conductively connected (not shown) to the electrodes of the in-line gun system 14. The contact pins are followed by grid electrodes 23, 24, focus electrodes 25, 26 and a convergence cup 27. Inside the grid electrode 23, cathodes 22 are arranged which are shown only schematically in broken lines. The first grid electrode 23 is also called control grid, and the second grid electrode 24 is also called screen grid. The cathode together with the control grid and the screen grid is called triode lens. The focus electrodes 25, 26 form a focusing lens. The individual parts of the in-line electrode gun 14 are held together by two glass beads 28.
The focus electrode 25 consists of 4 cup-shaped electrodes 25.1 to 25.4, of which two each are joined together at their free edges and thus form a cup-shaped electrode. In all electrodes of the in-line gun system 14, there are three coplanar aperatures through which the electron beams 1, 2, 3 produced by the three cathodes 22 can pass. Three beams 1, 2, 3 are thus produced in the in-line gun system which strike the Luminescent Layer of the screen 11. In order to change the shape of the beam spot to obtain improved sharpness of the reproduced image, a suitable astigmatism is imparted to the in-line gun system. This effect is obtained by a slit diaphragm in the grid electrode 24 of the triode lens and by plates on both sides of the beam plane or on both sides of the beams in the focus electrode(s).
It is necessary to divide the astigmatism of the beam system between the triode lens and the focusing lens. The triode lens forms a smallest beam section which--in analogy to optics--is imaged on the screen with the following lenses. The astigmatic construction of this triode lens also leads to an astigmatism of the aperture angle of the bundle of rays emerging from the triode lens. A larger aperture angle facilitates defocusing of the image of the smallest beam section and the viewer of the color picture tube focuses on the plane with the larger aperture angle, i.e., the vertical and not the horizontal focal line of the astigmatic beam section of the triode lens is imaged on the screen. On the other hand, the aperture angle must not become too large, because then the bundle of rays moves to the bordering region of the imaging lenses. The large spherical aberration of these rather small electrostatic lenses does not permit a sharp image. Therefore, a sufficient astigmatic deformation of the bundle of rays is possible only if it is partly effected in the last focusing lens of the beam system where the aperture angle of the bundle of rays is no longer influenced.
FIG. 3 is a top view of the cup-shaped focus electrode 26. In the bottom of the focus electrode 26, there are three coplanar apertures 30 for the passage of the electron beams 1, 2, and 3, respectively. At the walls 32 of the focus electrode 26 two plates 31 are attached opposite each other, each of which has three curved portions 33. These curved portions 33 project into the apertures 30. The plates 31 can also consist of three individual curved portions 33. In the embodiment shown in FIG. 3, the curved shape of the portions 33 corresponds to an arc of a circle. The shape of the portions 33 can also be elliptic or parabolic or have a similarly curved shape. The distance w ₁ between the opposite vertices of the portions 33 projecting into the central aperture is smaller than the distance w ₂ between the opposite vertices of the portions 33 for the outer apertures 30. Furthermore, the vertices of the portions 33 for the outer apertures are not on the center line of the outer apertures 30. In order to make this clear, the distance of the central points of the apertures 30 from each other is designated by the letter S in FIG. 3. The distance of the vertices of the outer portions 33 from the central vertex in the plate 31 is designated by s ₁ . It is clear that the value s ₁ is smaller than the value S. This makes it possible to influence the angle the outer electron beams 1, 3 make with the central electron beam 2 to achieve static convergence.
FIG. 4 is a section of the focus electrode 26 along line IV--IV of FIG. 3. The apertures 30 in the bottom of the focus electrode 26 have burred holes whose height for the individual apertures can be different. The plates 31, which may be attached to the wall 32 of the focus electrode 26 by weld spots 34, are arranged in a defined spaced-apart relation with respect to the inner edge of the burred holes. The distance from the bottom of the focus electrode 26 to the lower edge of the portions 33 of the plates 31 projecting into the apertures 30 is designated by the letter d. The distance d ₁ for the portion 33 projecting into the central aperture 30 is larger than the corresponding distances d ₂ of the outer portions 33 from the bottom of the focus electrode 26. By varying the distance d, the astigmatism of the focus electrode can be influenced. It is thus possible to choose the distances d of the various portions 33 from the bottom of the focus electrode individually in order to optimize the adjustment of the astigmatism individually for each electron beam. The height of the portions 33 of the plates 31 is designated by the letter b. By varying this height b, the astigmatism of the focus electrode can also be changed. Here, too, it is possible to determine the height b individually for each portion 33 in order to optimize the adjustment of the astigmatism for each electron beam. In the embodiment shown in FIG. 4, the height b ₂ of the outer portions 33 is larger than the height b1 of the inside portion 33.
The plates 31 described above do not only influence the astigmatism of the focusing lens, but also the other lens aberrations, i.e., the spherical aberration and the further higher-order aberrations. This influence is different for each of the embodiments described above. The higher-order aberrations can be seen mainly at the edge of the picture. They can be minimized by a suitable combination of the plates at the electrodes of the focusing length. It is possible, for example, to distribute the correction to the two focus electrodes or to impress too strong an astigmatism on one of the two focus electrodes, with partial compensation at the other focus electrode.
By the use of the plates 31 described above, it is possible to adjust the astigmatism very finely, thus producing an improved sharpness across the entire screen. By the fine adjustment of the static convergence, which is possible as well, the sharpness can also be improved. Furthermore, the dynamic convergence is improved, too.

 Deflection unit for a cathode-ray tube:

In cathode-ray tubes which require a precise specific electromagnetic deflection field configuration as for example, in self-converging color television picture tubes, an accurate distribution of the coil windings has to be maintained on the inside of the deflection unit. In practice, this requirement has been met with the aid of toroidal coil windings, but with respect to the more sensitive saddle-type coils this problem has not yet been solved satisfactorily, especially when large numbers of winding turns are to be accommodated. With respect to saddle-type coils the invention proposes to solve this problem by placing the windings into grooves.


International Standard Electric Corporation (New York, NY)
Inventors:Nelle, Friedrich (Straubing, DE)

1. A deflection unit for a cathode-ray tube, which is arranged toroidally around the neck of the tube and opens up in a trumpet-like manner towards the screen, and produces an electromagnetic field for deflecting one or more electron beams, and in which, at least in one direction of displacement, the deflecting field is produced by a set of saddle-type coils, the windings of which are wound on to a coil form on the face sides and on the inner surface of the deflection unit, wherein the improvement comprises;

each of the two halves of the saddle-type coil is arranged on one half of a coil form comprising two parts, with grooves determining the exact coil winding distribution being provided for in the surface of the coil form facing the tube wall;

the groove cross-sections are so designed that said grooves are almost completely filled with wires; and

at least some of said grooves deviate in their direction from the planes of the tube axis.


2. Deflection unit of claim 1, wherein one coil form for the coils of a first direction of displacement, and a further coil form for the coils of a second direction of displacement, are arranged in such a way into one another that the trumpet-like portions of the coil forms will come to lie almost completely on one another.

3. Deflection unit of claims 1 or 2 wherein the coil form is produced by being injection-molded on to the toroidal core.

4. Deflection unit of claims 1 or 2, wherein the wires on the face sides are guided in external grooves, and that at the slots formed as a continuation of the grooves on the face sides, the one side of the slots towards which the wires are turned out of the groove and into the external groove protrudes either from one of the face sides or from both.

5. Deflection unit of claim 4, wherein the web between the slots is arranged slantingly with respect to a plane extending vertically in relation to the tube axis.

Description:

BACKGROUND OF THE INVENTION

The present invention relates to a deflection unit (yoke) for a cathode-ray tube, which is arranged toroidally around the neck of the tube and opens up in a trumpet-like manner towards the screen, and produces an electro-magnetic field for deflecting one or more electron beams, and in which, at least in one direction of displacement, the deflecting field is produced by a set of saddle-type coils, the windings of which are wound on to a coil form on the face sides and on the inner surface of the deflection unit.

With respect to deflection units, it is a general requirement to achieve the necessary field pattern by way of the physical configuration of the deflection coils.

The required accuracy of the field pattern to be formed is particularly high in the case of deflection units which, owing to the shape of the picture tube, open up in a trumpet-like manner, especially in the case of color television picture tubes having high deflection angles.

Such high requirements can be met approximately by employing, for example, toroidal coils.

In the case of saddle-type coils having the advantage of a higher sensitivity over the toroidal coils, this has far less been able to achieve up to now owing to the more difficult geometry and for reasons of the difficulties in manufacture resulting therefrom, especially when a high impedance and, consequently, a large number of turns is required for circuit-technical reasons.

From the German Published Patent Application (DT-OS) Nos. 26 01 205 and 26 30 297, a deflection unit with saddle-type coils has become known, the windings of which are guided on the face sides of the yoke in grooves, with a possibility of providing further points of support on the inside surface of the yoke.

A similar point-wise fixing of the winding turns is also found in an example of embodiment relating to a deflection unit with saddle-type coils as disclosed in the German Printed Patent Application (DT-AS) No. 26 15 126. The guiding of the winding turns on the inside of the yoke by way of axial grooves in the core material is disclosed in the German Petty Patent (DT-GM) No. 74 41 864.

SUMMARY OF THE INVENTION

It is the object of the invention to provide a deflection unit of the type mentioned hereinbefore, which permits the formation of a desired field pattern and which, at the same time, enables an exact fixing of the coil windings also in the case of a large number of turns, without having to modify the contours of the core.

According to the present invention, each of two halves of a saddle-type coil is arranged on one half of a coil form consisting of two parts, with grooves determining the coil winding distribution being provided for in the surface of the coil form facing the tube wall.

As an advantage over the conventional arrangements, practice has shown that by applying the solution according to the invention, e.g. to shadow-mask type color television picture tubes having several electron beams, besides the adjustment of the deflection unit on the neck of the tube, there are not required any further means for achieving the desired convergence, and that this convergence behavior is also reproducible under mass-production requirements. According to another advantage of the invention, it is not so important for the individual wire to assume an exact position in the respective groove, as long as it is safeguarded that the wires are evenly distributed for filling the grooves.

It is also considered to be very advantageous to be able to choose from a large number of easily deformable materials, such as the injection-moldable thermoplast or the thermally deformable plastic foil, for manufacturing the coil form. This coil form does not need to consist of the same material as the toroidal core which is difficult to process and to form.

According to one advantageous further embodiment of the invention, it is proposed to design the groove cross-section also for a different occupation by wires, in such a way that the inserted wire or that the inserted wires will almost completely fill out the grooves, thus further increasing the accuracy of the winding distribution.

Moreover, it is proposed to arrange grooves also in planes other than those in which the tube axis is lying, or else to design the grooves to have a bent or curved form. In this way, it is possible to take more influence upon the pattern of the deflecting field than was possible with the hitherto conventional solutions.

As another advantageous further embodiment of the invention, it is also possible to arrange several coil sets, for example, for several directions of displacement, into one another as will still be described more precisely hereinafter with reference to an example of embodiment.

BRIEF DESCRIPTION OF THE FIGURES

Further details of the invention will now be explained in greater detail with reference to FIGS. 1 to 4 of the accompanying drawings, in which:

FIG. 1 is a part-sectioned view taken through a schematical example of embodiment of the invention;

FIGS. 2 and 3 show views of the face sides of a coil form according to the invention with part-sectioned views and winding examples; and

FIG. 4 is the schematical part-sectioned view taken through an example of embodiment comprising two sets of coils arranged into one another.

DETAILED DESCRIPTION OF THE INVENTION:

FIG. 1 shows an example of embodiment relating to a deflection unit arranged on the neck of the tube (7) and which, apart from the saddle-type coils (2), as an example of a further direction of displacement, still shows toroidal coils (8) which are wound around the toroidal core (1). According to the invention, grooves (5) are arranged in the inner surface (3) of the yoke in the coil form (4). There are various ways of designing these grooves (5). Thus, among others, these grooves may be cornered and provided with flat walls following the shape of the coil form, and equally well it is possible to provide round or hollow grooves. These grooves (5), for example, may be obtained by folding a formable foil. They may be wider than deep, or, conversely, deeper than wide, and the webs forming between them may be narrower than the grooves themselves. Likewise, also parts of the coil form may be removed between the grooves. The turns of the windings (6) during the winding operation are led in a way customary to the person skilled in the art, by coming from a groove (5) through the slots (9) into the external groove (10) in which they are led until entering the next groove (5). Preferably, the grooves (5) are almost completely filled with the winding turns (6).

Moreover, and in accordance with an advantageous further embodiment of the invention, FIG. 1 shows slots (9.1) to be provided for in the external groove (10), with the one side thereof protruding from the face side (13). In order to achieve this, the webs between the slots in this example of embodiment are arranged slantingly with respect to a plane extending vertically in relation to the tube axis. In this way the guiding of the wire is substantially improved during the operation of winding the coils, thus enabling a quicker and more reliable winding operation.

FIGS. 2 and 3 show a coil form according to FIG. 1 with a view on to the two face sides. Wire winding example are shown and become more clearly evident from the part-sectioned views on the coil form as regards the direction of the wire turns. As is shown in FIG. 2, the grooves (5) are provided in this case to have straight side walls, with the planes thereof extending parallel in relation to the tube axis in order thus to be able to make the tools, e.g. for a manufacture in accordance with the injection molding process, as well as the device for winding the coils (2), as simple as possible. By distributing the grooves (5) on the inner surface (3) of the coil form (4), as well as by them deviating from the radial direction, it is possible to take influence upon the configuration of the deflecting field, in order to achieve, for example, a field distribution as disclosed in the German Published Patent Application (DT-OS) No. 24 11 084 for color television picture tubes. But also grooves (5) in other planes are possible. The grooves (5) may also have a bent or curved design, as already mentioned hereinbefore.

FIG. 4 shows a second example of embodiment of the invention. According to a further embodiment of the invention, two coil forms (4.1, 4.2) are arranged into one another in this case, in order thus to produce deflecting fields for displacing electrons in two directions. Relative thereto, for example, it is also within the scope of the invention to produce the coil form (4.1) by being injection-molded on to the core (1).