JPH0330244A - Display tube and manufacturing method of the same - Google Patents

Abstract

PURPOSE: To prevent the vibration of a shadow mask from being transmitted to magnetic shields by interconnecting, using a component element of a nonmagnetic substance, inner magnetic shields comprising two complementary parts, and mounting the magnetic shields inside a display tube. CONSTITUTION: Internal magnetic shields 19 are secured to the support strip 12 of a shadow mask support device at their respective corners by their flanges 21 and have two complementary parts 15, 16 spaced apart by a distance (d) and located face-to-face, magnetic shielding depending on the distance (d). The parts 15, 16 are connected together by a component element 17 of a nonmagnetic substance during manufacture of a picture tube in such a way as to form the magnetic shields 19, and then the magnetic shields 19 are secured to the picture tube. Thereby tire correctness and color purity of an image displayed are guaranteed, and magnetic shielding unaffected by the vibration of a shadow mask 10 is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a display tube having an internal magnetic shield consisting of two complementary parts and a method for manufacturing the same.

(Prior Art) An internal magnetic shield consisting of two complementary parts placed opposite each other at a short distance shields the electron beam generated within the display tube from external magnetic fields, such as the earth's magnetism. play a role This magnetic shielding depends on the value of the distance between the two parts. In order to avoid undesirable magnetic field effects on the path of the electron beam, it is important that this distance remains virtually unchanged during operation and throughout the useful life of the display tube.

However, it has been found difficult to maintain the distance between the sections constant over the useful life of the display tube, especially in large size display tubes.

SUMMARY OF THE INVENTION The present invention provides a magnetic shield consisting of two complementary parts placed facing each other at a short distance, with the distance between the parts being virtually unchanged. A particular object of the present invention is to obtain a display tube having the following characteristics and a method for manufacturing the same.

Means for Solving the Problems According to the invention, a method for manufacturing a display tube of the type described at the outset comprises positioning two parts facing each other with a non-magnetic gap formed between them. , etc., are interconnected by a component of non-magnetic material bridging said gap, and then a magnetic shield is installed within the display tube.

It has been found in practice that this method ensures that the distance between the parts remains sufficiently constant throughout the useful life of the display tube. Moreover, the two parts of the magnetic shield form one integrated whole before these parts are suspended, and are therefore easier to handle, while maintaining the magnetic shield function. It becomes easier to attach the magnetic shield to the Furthermore, a precise and rigid connection of the two parts with the desired mutual spacing is obtained in a simple manner.

It is known from JP-A-63-13238 to connect two parts of a magnetic shield, each separately attached to the support frame of a shadow mask, with a sheet of glass frit or similar material. There is.

In a preferred embodiment of the method of the invention for simply, quickly and securely interconnecting two parts, the connection of the two parts is carried out by attaching a non-magnetic metal or alloy to these parts.

In another preferred embodiment of the method of the invention, in which a shadow mask having a large number of apertures is coupled into the display tube during a separate manufacturing step, the magnetic shield is mechanically decoupled from the shadow mask and inserted into the display tube. mounted on. This prevents vibrations of the shadow mask from being transmitted to the magnetic shield. This vibration can cause undesirable changes in the mutual spacing of the parts of the magnetic shield.

The invention also includes a container with a viewing window, an electrode system for generating at least one electron beam, and an internal magnetic shield located between the electrode system and the viewing window, the internal magnetic shield comprising two In display tubes consisting of two spaced apart and complementary parts, the two parts are connected to each other by means of a non-magnetic metal or alloy component, thereby providing a sufficiently constant magnetic shielding throughout its useful life. It is intended to provide a display tube.

a viewing window, a shadow mask coupled within the container and having a plurality of apertures, an electrode system for generating at least one electron beam, and an internal magnetic shield mounted within the container and located between the electrode system and the shadow mask. In a display tube, the display tube has a container comprising:
A display tube in which the magnetic shield is mounted within the display tube without being mechanically coupled to the shadow mask, and the two parts are connected to each other by a structural element of non-magnetic material, Has magnetic shielding that ensures accurate color purity and is not affected by shadow mask vibrations.

According to a preferred embodiment of the display tube of the invention, the shadow mask comprises a flexible component connected to a support element provided on the display tube, and the sections of the magnetic shield are respectively connected to the associated support element. By providing respective suspension means, a simple, non-mechanically coupled connection of the shadow mask and the magnetic shield within the display tube is obtained.

(Example) The present invention will be described below by way of example with reference to the accompanying drawings.

The color picture tube shown in cross-section in FIG. 1 has a container with a generally rectangular display window 1, a cone 2 and a neck 3. Inside the neck 3 are three electron beams 5, 6 and 7.
There is an electrode system 4 with three electron guns generating . The electron beam is generated in a plane (in this case the plane of the figure) and directed towards an internal display screen 8 which is provided on the display window l and which consists of a number of phosphor elements; The device is coated with an aluminum layer and emits red, green and blue light. The phosphor layer has, for example, the form of a stripe, and the longitudinal direction of these stripe-like elements is perpendicular to the plane passing through the electron gun (in this case the plane of the drawing). The electron beams 5, 6 and 7 are deflected onto a display screen 8 along their path by a plurality of deflection coils 9 arranged coaxially around the tube axis, and are deflected by a shadow mask 10 made of a thin metal plate. Pass through aperture l1.

The longitudinal direction of this aperture extends parallel to the phosphor elements of the display screen 8. The three electron beams 5, 6 and 7 pass through the aperture at small angles to each other, so that they each impinge on only one colored phosphor element. A two-element magnetic shield 19, which in this embodiment is frustoconically shaped and has substantially square ends, is provided with a flange 21.

This magnetic shield 19 reduces the adverse effects of external magnetic fields, such as terrestrial magnetism, on the electron beam path.

In this embodiment, the internal magnetic shield 19 is fixed at each corner by its flanges 2l to the support strip 12 of the shadow mask support device. The internal magnetic shield l9 is
Two complementary parts 15. located facing each other and separated from each other by a distance d. It has 16. The magnetic shielding depends on this distance d. In fact, this distance d is determined by the fact that during the manufacture of the picture tube the aforementioned parts 15 and 16 are first connected to each other by means of a non-magnetic component l7 to form a magnetic shield 19 (second
When this magnetic shield 19 is then fixed to the picture tube (as shown schematically in the figure), it has been found that it remains reliably constant during the useful life of the picture tube. Before interconnecting the two parts 15 and 16, these parts are positioned exactly at the distance d required for the desired magnetic shielding (for example 5 mm). Moreover, the fixation of the two parts to the picture tube is
This is simplified by the fact that these two parts can be treated as one integrated whole. The mechanical stability of this magnetic shield 19 within the picture tube is thereby also improved. In the event of shock and/or vibration, the two parts15. 16 move together in the same way, so these two parts 15. The distance d between 16 remains unchanged.

The magnetic shielding therefore remains constant. For example, a curable synthetic resin can be used as the material for the structural element 17.

Preference is given to using non-magnetic metal or alloy components fixed to the two parts of the magnetic shield, for example by welding, so that adequate mechanical stability of the two-part magnetic shield is obtained in a simple manner. Alloys of Cr, Ni and Fe are particularly suitable because of their non-magnetic properties and ease of processing.

It will be clear to those skilled in the art that the non-magnetic materials and alloy compositions used can be of many different types and the invention is therefore not limited to the examples.

The component I7 can be a strip or a plate in the form of a small circle, which can be connected both inside and outside the parts 15 and 1G.

Adequate mechanical stability of the connection between the two parts 15 and 16 is achieved by means of four structural elements 35 interconnecting the free ends of parts 15 and 16, as schematically shown in FIG. It is preferable to obtain The mechanical stability of the connection is improved even further if the two parts of the magnetic shield are connected along substantially the entire length of their opposing sides. This connection can be obtained by one suitably large or several small non-magnetic materials.

Since the shadow mask 10 and magnetic shield 19 are also typically made from thin metal sheets, they are both susceptible to vibrations and shocks. shadow mask io
In order to prevent the transmission of unwanted vibrations to the shield or vice versa, the shadow mask 10 is inserted into the picture tube without being mechanically coupled to the magnetic shield 19, as shown in FIG. 4, according to the invention. Preferably, it is attached. The shadow mask 10 is mounted within the picture tube by flexible elements 22 provided at the corners of the shadow mask 10. Each flexible element 22 is connected to a support element 23 provided at a corresponding corner of the viewing window 1. A two-part magnetic shield 19 is connected in the picture tube by means of a flange 21 and a support element 24 provided, for example, at the corner of the display window l. The flange 21 can be connected directly to the support element 24 or in another embodiment using suspension means, for example a flat elastic element.

The mechanical stability of the two-part magnetic shield 19 is determined according to the invention by the two parts 15 and 16 of the magnetic shield 19.
Safety is ensured by connecting it to a structural element 17 made of non-magnetic material.

The support elements 23 and 24 may be separate support elements, but the fifth
Preferably, the magnetic seal 19 and the shadow mask IO are mounted in the picture tube using the same support element 25, as shown schematically in the figure. Each support element 25 is provided, for example, with a conical free end 26 to which a flexible element 22 is connected. In this embodiment, a shadow mask 10 and a support frame 2 are used.
9 and at the corners of this support frame 29 flexible elements 22 are provided. However, in other embodiments it is possible to suspend the shadow mask within the picture tube without a support frame.

The magnetic shield 19 is provided with a flange 28 to which is connected a suspension means 27 (for example a flexible element), which is itself connected to the free end 26 of the associated support element 25 .

Therefore, the shadow mask IO is suspended separately from the magnetic shield 19 in a simple manner.

It will be apparent to those skilled in the art that many variations within the spirit of the invention are possible.

Thus, for example, it is possible to use other types of shadow mask and magnetic shield suspensions than those described above.

Although the invention has been described with respect to a color picture tube with a shadow mask, the invention also relates to a display tube without a shadow mask for displaying black and white images.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of one embodiment of the display tube of the present invention, FIG. 2 is a schematic sectional view of a magnetic shield consisting of two parts, FIG. 3 is a schematic perspective view of another embodiment of the magnetic shield, and FIG. FIG. 4 is a schematic sectional view of another embodiment of the display tube of the present invention, and FIG. 5 is an enlarged schematic sectional view of a part of still another embodiment of the display tube of the present invention. 1... Display window 4... Electrode system 10... Shadow mask l1... Aperture 12... Support strip 15. 16... Two parts of magnetic shield 17...
- Connecting element l9...magnetic shield 21. 22...Flange 22...Flexible elements 23, 24. 25...Support element 27...Suspension means 29...Support frame

Claims (1)

[Claims] 1. A method for manufacturing a display tube having an internal magnetic shield consisting of two complementary parts, wherein the two parts are positioned facing each other with a non-magnetic gap formed therebetween. A method of manufacturing a display tube, characterized in that these two parts are interconnected by a component of non-magnetic material bridging the gap, and then a magnetic shield is installed within the display tube. 2. The method of manufacturing a display tube according to claim 1, wherein the two parts are connected by a connecting element made of a non-magnetic metal or an alloy. 3. A shadow mask having a large number of apertures is connected to the display tube during a separate manufacturing process, and the magnetic shield is connected to the display tube without being mechanically coupled to the shadow mask. 3. The method for manufacturing a display tube according to 1 or 2. 4. having a container with a viewing window, an electrode system for generating at least one electron beam, and an internal magnetic shield located between the electrode system and the viewing window, the internal magnetic shield comprising two separate A display tube comprising complementary parts facing each other, characterized in that the two parts are interconnected by a non-magnetic metal or alloy component. 5. a viewing window, a shadow mask coupled within the container and having a plurality of apertures, an electrode system for generating at least one electron beam, and an interior mounted within the container and located between the electrode system and the shadow mask; The container is equipped with a magnetic shield, and the magnetic shield is 2
In a display tube consisting of two spaced apart, facing complementary parts, the magnetic shield is mounted within the display tube without being mechanically coupled to the shadow mask, and the two parts are
A display tube characterized in that it is interconnected by components made of non-magnetic material. 6. Claim 5, wherein the shadow mask comprises a flexible element connected to a support element provided on the display tube, and the magnetic shield portions each comprise a suspension means connected to the associated support element. Display tube as described. 7. Display tube according to any one of claims 4 to 6, wherein the two parts of the magnetic shield are interconnected at least by their free ends. 8. A display tube according to any one of claims 5 to 7, wherein the two parts of the magnetic shield are interconnected along substantially the entire length of their facing sides.