JP2804137B2 - Materials and processes for manufacturing CRT tension masks - Google Patents

Description

The present invention relates to a tension foil color cathode ray tube, and more particularly to a tension foil shadow mask made of an improved alloy and a process for manufacturing such a cathode ray tube. Includes a heat treatment of the nickel-iron alloy to obtain the desired combination of mechanical and magnetic properties required for the effective operation of the foil shadow mask. A front assembly with such a mask is also disclosed. It is known that cathode ray tubes having a flat face plate and a flat tension foil shadow mask opposed thereto have many advantages over conventional cathode ray tubes having a curved face plate and a curved shadow mask. The main advantage of a flat face plate cathode ray tube with a tension mask is its large electron beam output processing capability, which can increase the brightness of the screen. The output throughput of cathode ray tubes with conventional curved masks is limited by the thickness of the mask (5-7 mils) and the fact that it is mounted without tension. Eventually, the mask tends to enlarge or be curved at the brightest screen, where the intensity of the electron beam impact and consequently the heat is the highest. Color shading occurs when the mask spreads toward the face plate, or when the beam passage holes in the mask are out of registration with the relevant phosphor points or lines on the face plate. Tension foil masks behave very differently from curved non-tensioned masks when heated. For example, when the entire mask is heated evenly, the mask expands and relaxes. The mask remains flat, with no swelling or distortion, and the mask expands to a point where tension is completely eliminated. Immediately before all tension is lost, corners may wrinkle. If a small portion of the tension foil mask is heated differently, the heated portion expands and the unheated portion contracts immediately, causing only a small displacement displacement in the mask plane. However, the mask remains flat and is adequately separated from the face plate, and eventually no color shading is observed.

The mask must be supported under tension to keep the mask flat while the cathode ray tube is operating. The amount of tension required depends on how much the mask material is heated and expanded during operation of the cathode ray tube. Materials with very low coefficients of thermal expansion may require low tension. However, in general, the higher the tension, the more heat is received and the larger the flow of the electron beam that can be handled. Therefore, the tension should be as high as possible. However, if the tension is too high, the mask may be torn, so that the tension of the mask is limited.

The foil mask is tensioned according to known practices. A convenient method is to apply a heated platen to both sides of the foil mask and thermally expand the mask. The inflated mask is pinched by the fixture and creates tension when cooled. The mask can also be inflated by exposure to infrared radiation, heating by electrical resistance, or spreading by applying mechanical force to its edges. The foils made of the alloy, in addition to having the construction described here, can be mechanically, particularly suitable for use as a tension foil shadow mask, if subjected to heat treatment and gradual cooling according to the invention. It has a unique combination of thermal and magnetic properties. The as-cast or heat-treated alloy must be ductile so that it can be hot or cold rolled into a foil having a thickness of less than 2 mils, preferably as thin as 1 mil, and even 0.5 mils. 1 mil foil when rolled, at least 0.8
Typically, there is a reduction in area by elongation of%, (at least 1% is better).

In order to withstand the force of the tensioning operation, the mask material should be about 8 ksi or more (more preferably about 100 ksi or more.
2% offset)). The mask material must also be capable of withstanding a tensile load of at least about 25 Newtons / cm (and more preferably at least 65 Newtons / cm). The mask material further
It must have a coefficient of thermal expansion much smaller than the faceplate glass.

The mask material must have a special combination of magnetic properties in addition to the described mechanical properties. In this context, it is important to have the highest possible permeability while maintaining the required mechanical properties. The permeability must be above about 6000 (more preferably above about 10,000, and most preferably above 60,000). The maximum coercivity is preferably about 1.0 Oe or less, and more preferably about 0.5 Oe or less.

In the production of curved masks, curved screen type standard color cathode ray tubes, it is well known that a shadow mask is heat-treated before being formed into a dome shape. In conventional non-tensioned shadow masks, work-hardened by rolling several times on steel to reduce the thickness to a specified thickness, typically about 6 mils,
Typically shipped to cathode ray tube manufacturers. The mask is heat-treated for annealing so that the mask can be pressed into a dome shape (typically at a temperature of about 700 to 800 ° C)
Must be softened. Annealing enhances the coercivity of the mask, which is a desirable property from the perspective of magnetic shielding of the electron beam. After gradual work hardening of the mask as a result of the embossing and embossing work, the mask is in a dome shape to further enhance the magnetic shielding.
Re-annealing is known in the prior art.

The foil to be used as a tension mask is also shipped in a cured state. In fact, for example 30,0
It is shipped much harder than a standard mask to provide the very high tensile strength required to maintain the required high tension level of 00 psi or higher. In the prior art, the annealing process with a relatively high annealing temperature, when applied to a flat tension mask, results in a widespread reduction in the tensile strength of the mask, which results in tensioning the material. -It is absolutely difficult to approve it because it makes it unsuitable for use as a mask.

Avedani, U.S. Pat. No. 4,210,843, describes an improved method of making a conventional color CRT shadow mask. That is, an improved method of making a curved shadow mask approximately 6 mils thick and designed for use with a curved face plate is described. The method consists in providing a plurality of shadow mask blanks, each of which is made of gapless steel and each has a photo-etched hole mold. The blanks were precision cold-rolled to sufficiently hard conditions and cut from 6-8 mil thick steel foil. The blank material is subjected to a limited normalizing operation at a relatively low maximum temperature for a relatively short period of time sufficient to recrystallize the material without significant grain growth.

Each blank is tightened and stretched to form a concave shadow mask without vibration or roller leveler operation. Thus, undesired blank wrinkles, rolling markings, dents, tears or work hardening, which usually occur with these operations, are avoided. The final shadow mask uses a non-gap steel material and therefore has a hole pattern with improved sharpness as a result of the uniform stretching of the mask blank. The annealing operation has little effect on the magnetic properties of this type of steel. The coercivity of the material after fabrication is 2.0 Oe or more.

Prior to the present invention, there was no foil mask material with the desired combination of mechanical and magnetic properties as described herein. One of the materials used for the flat face plate cathode ray tube tension foil shadow mask was aluminum killed steel. This is AISI
1005, a cold-rolled capped steel commonly called "AK steel". The composition of AK steel is silicon 0.04%, manganese 0.16
%, Carbon 0.028%, phosphorus 0.020%, sulfur 0.018%, aluminum 0.04% and the balance iron and impurities.

(Percent (%) throughout the description and claims)
Are all weight percentages (%) unless otherwise indicated
It is. Invar, which has a nominal composition of 36% nickel and the balance iron, has also been proposed as a material that can be used in tension foil shadow masks. However, Invar
Because its thermal expansion coefficient is much smaller than the glass commonly used for CRT face plates,
It is generally considered unfit for purpose.

While AK steel can make fairly good foil shadow masks, it lacks certain important properties. For example, 1 mil thick AK steel has a typical yield strength of 75
It is in the range of ~ 80ksi. This is barely satisfactory in terms of strength. More importantly, AK steel has a much lower magnetic permeability than required, e.g.
It has a magnetic permeability of 0. Since the ability of a material to conduct magnetic flux decreases as the cross-sectional area decreases, cathode ray tubes with masks made of less than about 1 mil AK steel
Requires magnetic shielding both internally and externally. In the case of internal shielding alone, beam arrival misregistration due to the Earth's magnetic field, i.e., the change in beam arrival position on the reversal of the axial magnetic field component, is typically 1.7 mils, which is generally a tolerance. Significantly greater than the maximum of about 1 mil, which is considered within.

Also, AK steel is metallurgically dirty, including inclusions, flaws,
Misalignments, which hinder both the foil rolling process and the photoresist etching of the foil holes, result in high scrap rates and ultimately low yields.

Another notable disadvantage of the tension foil shadow mask of AK steel is the fact that as the applied tension increases, the permeability decreases and the coercivity increases.
Considering this in terms of image performance, increasing the tension of the AK steel foil shadow mask to increase the beam current and increase the brightness of the image shields the electron beam from the Earth's magnetic field. The ability to do so is reduced and the beam misregistration is increased.

Finally, AK steel is rusting, so be careful when storing it, and if possible, rust-proof. If rusting occurs, it must be removed in a separate production operation to keep the dimensions and shape of the holes and the thickness of the mask material unchanged.

In general, the present invention is intended to provide an improved shadow mask material for use in a color cathode ray tube having a tension foil shadow mask.

Accordingly, the present invention provides a foil shadow mask for use in a tension foil color cathode ray tube. The foil mask is made of an alloy comprising about 30 to about 85 weight percent nickel, about 0 to 5 weight percent molybdenum, and 0 to 2 weight percent of one or more of vanadium, titanium, hafnium, niobium. It is a thing.

Another general feature of the present invention is to provide an improved process for the manufacture of cathode ray tubes with tension foil masks having improved mechanical and magnetic properties.

The present invention therefore provides a process for the production of a tension mask color cathode ray tube having a phosphor plate on the inner surface and a face plate on the opposite side of the screen with the support structure of the mask. This process uses nickel-
Providing a perforated foil shadow mask made of an iron alloy, fixing said mask to said support structure;
Aligned with the phosphor screen under tension and subjected to thermal cycling to actually anneal the mask to a state with favorable magnetic and mechanical properties.

The features and advantages of the present invention are shown in the attached drawings (knot scale)
The invention is best understood by reference to the following description of a preferred embodiment of the invention in connection with. The same reference number represents the same part in several drawings.

FIG. 1 shows a flat face plate and tension plate.
1 is a side perspective view of a color cathode ray tube having a foil shadow mask, with a cross section cut away to show the position and relationship of the face plate and the tension foil shadow mask with respect to other major components.

FIG. 2 is a plan view of the foil shadow mask being processed.

FIG. 3 is a plan view of a flat glass face plate during processing showing the fluorescent screen area and the foil shadow mask support structure fixed to the face plate.

FIG. 4 is a perspective view of the funnel positioning and fritting fixture, showing the funnel and the face plate to which it is attached resting on the fixture.

FIG. 5 is a partial detail of an elevational cross-sectional view showing the attachment of the funnel to the face plate.

To facilitate an understanding of the process and materials according to the invention and their relation to the production of a color cathode ray tube with a tension foil shadow mask, a brief description of this type of cathode ray tube and its main components is given below. State.

A color cathode ray tube 20 having a tension foil shadow mask is shown in FIG. The face plate assembly 22 basically comprises a flat face plate and a tension wheel shadow mask mounted adjacent thereto. The face plate 24, shown as a rectangle, has a phosphor screen 28, illustrated as having a phosphor pattern, in the center of the inner surface 26.
The aluminum thin film 30 is shown covering the phosphor pattern. Funnel 34 is attached to face plate assembly 22 at joint 35. The funnel sealing surface 26 of the face plate 24 is
Shown around 28. A frame-shaped shadow mask support structure 48 is shown at a location opposite the screen between the funnel sealing surface 36 and the screen 28, and includes a face mask.
It is mounted close to the plate 24. Support structure 48
A metal shadow mask 50 is provided to provide a mounting surface at a distance Q from the screen 28 under tension. The phosphor pattern is opposed to the hole pattern of the mask 50. The holes shown are exaggerated for illustration purposes, for example, in a high resolution color cathode ray tube, the mask has about 750,000 holes and the diameter of the holes is about 5 mils on average. . As is known in the art, foil shadow masks act as color-selective cathodes or "parallax barriers" such that the three-beam split beam reaches only a defined phosphor deposit on the screen. Make sure you do.

The longitudinal axis of the cathode ray tube 20 is indicated by reference numeral 56.
Magnetic shield 58 is contained within funnel 34. The high voltage for cathode ray tube operation is applied to the conductive coating 60 on the inner surface of the funnel 34 by the anode button 62, which in turn is connected to a high voltage lead 64.

A row of electron guns 68 is shown housed in the neck 66 of the cathode ray tube 20. The electron gun emits three separate rows of electron beams 70, 72 and 74, which stimulate the red, green and blue light emitting fluorescent elements on screen 28, respectively. Yoke 76 receives the scan signal and causes beams 70, 72 and 74 to scan screen 28. An electrical conductor 78 is provided in the opening of the shield 58 and is in contact with the conductive coating 60 to provide a high voltage connection between the coating 60, the screen 28 and the shadow mask 50.

Showing the two main parts labeled "under machining"
This will be described below. One is a shadow mask, which is shown schematically in FIG. In the shadow mask 86 being processed,
Using a mask that is an optical stencil, there is a central opening 104 facing the phosphor pattern deposited on the screen of the face plate. The central portion 104 is surrounded by a perforated portion 106, the perimeter of which engages a frame for tensioning during the process of tensioning and tightening the mask. This will be removed in a later step.

The face plate 108 being processed is illustrated in FIG. 3 and has on its inner surface 110 a centrally located screen portion 112 which receives a predetermined phosphor pattern in a reliable manner. A frame-shaped shadow mask support structure 114 is secured to the opposite side of the screen 112, the support structure having a surface 115 for receiving the foil shadow mask and mounting at a distance Q from the screen under tension.

A process according to one of the features of the present invention is to provide a foil shadow mask with openings characterized by being essentially composed of a nickel-iron alloy and to provide a mask 86 with a face plate. 108 mask support structure 114
In a state in which there is tension, it is configured by registering and fixing to the fluorescent screen. The process is further characterized by subjecting the mask to a thermal cycle to partially anneal to a state having favorable magnetic and mechanical properties.

According to the present invention, certain nickel-iron alloys desirably have a low content of alloying additives, but when heat treated and cooled under controlled conditions, when formed into thin foils, It provides materials with mechanical and magnetic properties not found in known alloys that make them particularly suitable for use as tension foil shadow masks.

The desirable properties achieved by the process of the present invention are as follows. The alloy foil is at least about 80 ksi, preferably at least about 100 ksi, and most preferably at least about 150 ksi, so as to withstand the tensile load applied to the foil when used as a tension foil shadow mask.
Yield strength (0.2% offset). This yield strength must be combined with the magnetic properties of high magnetic permeability and low coercivity. The permeability should be at least about 6000, preferably at least about 10,000, and most preferably at least 100,000. The coercivity should not exceed about 2.5 Oe
Preferably it is less than 0.5 Oe.

Specific examples of alloys that respond to heat treatment and the manufacture of tension foil shadow masks according to the present invention are HYMU80,
Known nickel-iron-molybdenum alloys marketed under the trade names YeP-C and Moly-Permalloy. This alloy has a composition of about 80% nickel, 4% molybdenum, and the balance of iron and impurities. Rolled and hard, 80
Ni-4Mo-Fe foils typically have a high yield strength of 155-160 ksi, but have poor magnetic properties, for example, a permeability of less than 3,000. To provide good magnetic properties, such as those used in tape recorder heads, the material is conventionally annealed at 1120 ° C for 2 to 4 hours and then cooled in a furnace to 600 ° C. A fully annealed alloy foil has good magnetic properties but poor mechanical properties. Permeability would be around 300,000, but with yield strengths in the range of 20-40 ksi, this alloy, when sufficiently annealed, would obviously be suitable for use in tension foil shadow masks. It becomes inappropriate.

However, when the 80Ni-4Mo-Fe alloy foil is partially annealed by the process of the present invention, it unexpectedly exhibits excellent properties as a material for manufacturing a tension foil shadow mask. As a result of the heating and cooling cycle according to the invention, the mechanical properties of the alloy are well maintained, while
Its magnetic properties are improved to the extent necessary for use as a foil shadow mask.

Surprisingly, with the heat treatment according to the invention, 80Ni-
It has been found that the magnetic properties of the 4Mo-Fe foil were actually improved, and were significantly improved when the foil was in tension. For example, a 1 mil thick 80Ni-4M without tension
The o-Fe foil has a magnetic permeability of 60, after heat treatment and adjustment according to the present invention.
000. However, when the same foil is tensioned at about 60 Newtons / cm, its permeability increases to 100,000. It should be noted that the same material does not show any noticeable change in permeability under tension in the conventional hard state. As a result of the increased permeability, 1 mil thick 80Ni-
The amount of beam misregistration of the 4Mo-Fe foil due to the earth's magnetic field when treated according to the present invention is much less than for 1 mil thick AK steel.

In terms of alloy composition, nickel-iron alloys are:
About 30 to about 80% by weight of nickel, about 0 to 5% by weight of molybdenum, and 0 to 2% by weight of one or more of vanadium, titanium, hafnium, and niobium, balance iron and miscellaneous impurities ( For example, carbon, chromium, silicon, sulfur,
(Copper, manganese). In a representative example, the contaminant impurities do not exceed 1.0%. Alloy is about 75-85% by weight
Of nickel, about 3 to 5% by weight of molybdenum, and the balance of iron and impurities. In one specific example, the alloy is about 80% nickel, about 4% by weight
Of molybdenum, and the balance of iron and miscellaneous impurities.

Partial annealing of the preferred material, in accordance with aspects of the present invention, may be performed as a separate step before mounting the mask on the mask support structure secured to the face plate. In order to achieve the desired combination of mechanical and magnetic properties, the foil must be subjected to a defined procedure of heat treatment and slow cooling according to the invention.

In a typical process according to the invention, a set of twelve hard, apertured masks of the shape shown in FIG. 2 are stacked for entry into the furnace. The process according to the invention is characterized by exposing the mask to thermal cycling in which the mask is partially annealed to obtain favorable magnetic and mechanical properties. The thermal cycle heats the mask to a temperature of about 400 ° C. or higher, and heats the mask at a temperature not higher than the temperature at which the mask alloy forms a solid solution for about 30 minutes or more, preferably 45 minutes or more. Cool slowly at a rate of about 5 ° C. or less per minute, preferably at a rate of about 3 ° C. or less per minute, until the recrystallization temperature, and the mask is in a tensioned state. The mask is fixed to a mask support structure that is attached to the face plate while being in place or is integral with the face plate. For example, a mask can be
Heat to a temperature between 00 ° C. for about 30 to about 60 minutes. The mask is then heated at a rate from that temperature to a temperature at which the material of the mask is sufficiently recrystallized to no more than about 5 ° C per minute, preferably less than 3 ° C per minute, and most preferably between 2-3 ° C per minute. Cool slowly. Longer heat treatments may be used, but no improvement in properties is expected. Heat treatment at the specified temperature followed by air cooling or cooling at a rate of about 5 ° C. per minute resulted in undesirable poor mechanical properties. While not wishing to be bound by any particular theory, the heat treatment disclosed herein is performed at a temperature well below the annealing temperature, followed by slow cooling, resulting in grain boundary precipitates. Believe that the Ni ₃ Fe table range regularity is obtained.

In accordance with the present invention, heating and cooling the assembly and foil at a slow rate partially anneals the foil mask and also provides a yield strength of 80 ksi or more, a magnetic permeability of about 6000 or more, It is effective in obtaining a coercive force equal to or less than Oersted and a thermal expansion coefficient equal to or greater than that of a face plate (glass). Continuing the process as described, the mask will surely have a yield strength of about 150 ksi or more, a permeability of about 10,000 or more, and a coercivity of about 1.0 or less. The foil can withstand a tensile load of about 65 Newtons / cm or more. It can also withstand about 75 Newtons / cm.

The slow cooling of the heat treatment of the mask described below is very similar to the sealing of the funnel and face plate in the stages of processing and manufacturing of frit color cathode ray tubes.

Following the initial implementation of the process of the present invention, the following was determined. That is, the heating and cooling conditions to which the tension mask is exposed during the frit cycle are such that a substantial improvement in the described alloy properties is obtained without the need for the separate heat treatment and slow cooling described above. tension·
The properties of the foil mask are not as good as those obtained when heating the material of the mask to the more desirable temperature of 500-600 ° C. However, if the brightness and resolution required for the cathode ray tube are not so high, the 80Ni-4Mo-Fe tension mask being processed during the frit cycle may be replaced by a 4
Heat slowly to 35 ° C, then frit
Cooling slowly at a rate of cooling during the cycle of less than about 5 ° C. per minute, preferably between about 2 ° C. and about 3 ° C .;
It has been decided that the finished mask should have the desired mechanical and magnetic properties.

For example, a yield strength between about 150 ksi and about 160 ksi when a tension foil mask that is not treated is tensioned at 30 Newtons / cm and subjected to a frit cycle.
A magnetic permeability between about 60,000 and about 100,000 and a coercivity of less than about 4 Oe are obtained. Beam misregistration is slightly higher than would be obtained if the foil had been separately heat treated, but still below the desired limits.

Accordingly, partial annealing according to the present invention is also performed during and as a result of thermal cycling during the process of sealing CRTs. The process will be described below.

As shown in FIG. 3, the shadow mask support structure 114
Is the internal surface of the faceplate between the peripheral sealing surface, indicated by the funnel sealing surface 113, and the screen surface.
Fixed on 110. The mask support structure 114 has a surface 115 for receiving and supporting a tensioned foil shadow mask. Mask support structure 114
Can consist of a stainless steel alloy, for example. The mounting of the support structure preferably relies on an opacifying frit.

Nickel-iron alloys include nickel between about 30 and about 80 weight percent, molybdenum between about 0 and 50 weight percent, and 0 and 2 weight percent of one or more of vanadium, titanium, hafnium and niobium. Provided is a percentage, with the balance consisting of iron and associated impurities, such as carbon, chrome, silicon, sulfur, copper, and manganese. In a typical example, the associated impurities are less than 1.0 percent. Further, in accordance with the present invention, the alloy may include between about 75 and 85 weight percent nickel and between about 3 and 5 weight percent molybdenum, with the balance consisting of iron and associated impurities. Preferably, the alloy is
About 80 weight percent nickel and 4 weight percent molybdenum, the balance being iron and associated impurities.

The alloy of the present invention is formed into a foil having a thickness of 0.001 inch or less.

The central face 112 of the foil is perforated to form a foil mask whose dimensions match the screen face 112 for color selection. The opening of the mask can be made by a photo-etching method of applying a photosensitive resist to the foil. The resist is hardened by exposing it except for the part that limits the range of the opening. The exposed metal portion defining the opening is etched.

The foil mask is then tensioned in the tension frame with a tension of at least about 25 Newtons / cm. In essence, the foil is sandwiched between two platens heated to 360 ° C, clamped in a tension frame, heated for 1 minute, and allowed to cool. It is also possible to obtain long and wide tension wheels. A pattern of phosphor deposits emitting red, green, and blue light, respectively, is sequentially formed on screen surface 112 by photo screening. The photo-screening step involves repeatedly aligning the foil with the phosphor screen surface by aligning the tension frame with the faceplate.

The foil making up the mask 86 is fixed to the mask support structure with the mask holes aligned with the pattern of phosphor deposits on the screen surface 112. The means for fixing the mask to the mask support structure may rely on welding with the same laser beam, with excess mask material removed with the laser beam. Face plate 10
Since 8 and the tension foil shadow mask 786 are rigidly connected to each mask support structure, the coefficient of thermal expansion of the alloy foil must be approximately equal to the coefficient of thermal expansion of the faceplate. A typical face plate has a thermal expansion coefficient of about 12 × 10 ^-6 and about 14 × ^-6 in
A glass that is between / in / ° C. Such matching of the coefficients of thermal expansion is necessary because the faceplate and mask are exposed to relatively high temperatures during the cathode ray tube manufacturing process. Although the coefficient of thermal expansion of the mask is allowed to be slightly higher than that of the face plate, it must be avoided that the coefficient of thermal expansion becomes significantly smaller than that of the face plate because the mask may be deteriorated in the manufacturing process.

FIGS. 4 and 5 show the use of a funnel positioning and frit substitute fixture to combine the faceplate 108 with the funnel 188 to form a faceplate funnel assembly. Faceplate 108 is shown mounted downwardly on surface 190 of fixture 186. The funnel 188 is shown resting thereon and in contact with the funnel sealing surface 113, which is the screen surface 112 on which the phosphor pattern has been formed as a result of a previous screen forming operation. Is shown in the vicinity. In FIG. 4, three points, 192, 193, and 194, are shown for performing the arrangement of the funnel and the face plate.
FIG. 5 shows details of an intermediate plane between the column 194, the face plate 108, and the funnel 188. The side 17 of the faceplate 108 is shown to be in line with the reference plane "C" of the funnel 188. The shadow mask 86 is shown in tension, with the preferred state shown attached to the shadow mask support structure 114.

Post 194 is shown as having two reference points 196 and 198 for positioning funnel 188 with respect to faceplate 108. The reference point is preferably
It consists of button-like carbon. This is because it must withstand the effects of high furnace temperatures that occur during the frit period.

Apply a paste-like frit that is transparent to the funnel 188
The face plate 108 is applied to a peripheral sealing surface 113, shown as a funnel sealing surface 113, for receiving the same. The faceplate 108 then combines with the funnel 188 to form a faceplate-funnel assembly. The frit is indicated in FIG. 5 by reference numeral 200, for example, Owens-Toledo, Ohio, USA.
It may be a product from Illinois, Frit No. CV-130.

The faceplate-funnel assembly is then heated to a temperature effective to allow the frit to penetrate and, after cooling of the assembly, to permanently secure the funnel to the faceplate. The step of fusing the funnel to the face plate is performed under conditions generally referred to as a frit cycle. In a typical frit cycle, the faceplate and funnel to which the tension foil mask is bonded is gradually heated to 435 ° C. and then cooled to room temperature, or to a temperature slightly above.
It is held for about 3 to 3 hours. The foil substantially recycles the alloy at a cooling rate of less than about 5 ° C per minute, preferably less than about 3 ° C per minute, and most preferably at a rate between about 2 ° C per minute and about 3 ° C per minute. It must be cooled to the temperature at which it crystallizes.

In accordance with the present invention and during the frit cycle, the heating of the assembly and foil and the slow cooling rate of the assembly and foil partially temper the foil mask and produce the desired mechanical and magnetic properties described above. It is effective for

Test results supporting the concept according to the invention are summarized by the following examples.

Example I The thickness of a cold rolled 80Ni-4Mo-Fe foil is 1 mil. In the as-received condition, the permeability of the foil is 3,00
0, coercivity 2.2oersteds, and yield strength is 156ksi.
The foil is heat treated at 500 ° C. for 60 minutes in a dry hydrogen atmosphere and then cooled to 200 ° C. at a cooling rate of 3 ° C. per minute.
Yield strength 192ksi, permeability 60,000, coercive force depending on heat treatment
A foil with 0.31 oersteds and an expansion coefficient of 13 × 10 ⁻⁶ in / in / ° C. is obtained.

Example II 42 Ni-Fe cold rolled 1 mil thick foil may be used. In the as-received state, the foil permeability is 3,00
0, coercivity 4.0oersteds, and yield strength is 110ksi.

The foil is heat treated in a dry hydrogen oven at 600 ° C. for 2 hours, and cooled to 200 ° C. or less at a cooling rate of 2 ° C. per minute. The magnetic permeability of the heat-treated and slowly cooled foil is 9,000 and the coercive force is
1.1oersteds, also the yield strength is 80ksi.

Example III 49 Ni-Fe 1 mil thick foil, as received, had a magnetic permeability of 3,200, a coercive force of 4.2 oersteds, and a yield strength of 11
5ksi. After heat treatment and slow cooling according to Example I,
The foil has a permeability of 10,000, a coercive force of 0.4 oersteds and a yield strength of 85 ksi.

EXAMPLE IV A 1 mil thick foil of 49Ni-4Mo-Fe has similar physical and magnetic properties as received to the foil of Example I. The permeability of the foil after slow cooling is 20,000, the coercive force is 0.3 oersteds,
The yield strength is 160 ksi.

Example V A 1 mil thick foil of 79Ni-2Mo-1V-Fe is expected to have similar physical and magnetic properties as received to the foil of Example I. After heat treatment and slow cooling, the foil is expected to have a permeability of 30,000, a coercive force of 0.3 oersteds and a yield strength of 160 ksi.

Example VI A 1 mil thick foil of 79Ni-2V-1Ti-Fe is expected to have similar physical and magnetic properties as received to the foil of Example I. The foil may be heat treated and slowly cooled according to Example I, after which the permeability is
Over 30,000 with coercivity of 0.3 oersteds and yield of 170
Expected to be ksi.

Example VII A 1 mil foil of 79Ni-4Mo-Fe was subjected to heat treatment and slow cooling by a conventional frit cycle in the as-received state, and then the same physical properties and magnetic properties as the foil of Example I were obtained. It is expected to have a characteristic. A frit cycle is a period of time in an open hearth with a peak temperature of 435 ° C. The total time required for the sample to pass from the furnace inlet to the outlet is about 3 to 3.5 hours. The foil is expected to have a permeability of about 60,000, a coercive force of about 0.4 oersteds and a yield strength of 155 ksi.

A foil shadow mask according to the present invention for use in a tension foil color cathode ray tube, i.e., a faceplate assembly for such a cathode ray tube, preferably comprises about 30 to about 85 weight percent nickel and about 0 to about 0 weight percent molybdenum. To 5% by weight of one or more of vanadium, titanium, hafnium and niobium between 0 and 2% by weight.
Such alloys have a yield greater than 80 ksi, a permeability greater than about 6,000, a coercive force less than about 2.5 oersteds, and a coefficient of thermal expansion that is about equal to or greater than that of the faceplate. Further, the mask is capable of receiving a tension of at least about 25 Newton / centimeters when the cathode ray tube is at ambient temperature.
Alloys according to the present invention can have a yield greater than about 150 ksi, a permeability greater than about 10,000, and a coercive force less than about 1.0. Further, for the composition of the mask alloy, the content is between about 75% to about 85% by weight of nickel, about 3% to about 5% by weight of molybdenum, with the balance being iron and associated impurities, preferably Has a composition of about 80 weight percent nickel, about 4 weight percent molybdenum, with the balance being iron and associated impurities.

Continuation of front page (56) References JP-A-64-42546 (JP, A) JP-A-64-42547 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01J 29 / 00-29/16 H01J 9/00-9/18

Claims (8)

(57) [Claims] 1. A foil shadow mask for use in a tension foil color cathode ray tube, comprising: a flat face plate; and a foil mask covered with a tension applied thereto. The nickel content is between about 30 and about 85 weight percent, the molybdenum content is between 0 and about 5 weight percent,
The alloying agent, selected from vanadium, titanium, hafnium, niobium and mixtures thereof, has a content of between 0 and about 2% by weight, with the balance being iron and alloys which are incidental impurities; The coefficient of thermal expansion of the alloy is substantially equal to or greater than the coefficient of thermal expansion of the face plate of the cathode ray tube, and the nickel content of the alloy is about 75 to about 85
Weight percent, the molybdenum content is between about 3 and about 5 weight percent, the yield strength of the alloy is greater than about 1,033 N / mm ² (150 ksi), the magnetic permeability is greater than about 10,000, and A foil shadow mask having a coercive force of less than about 80 A / m (1.0 Oe). 2. The shadow mask of claim 1 wherein said shadow mask is under a tension of at least about 25 Newtons / cm when said cathode ray tube is at ambient temperature. 3. A tension mask color cathode ray tube comprising: a face plate having a phosphor screen on an inner surface thereof; and a support structure for supporting a tensioned foil shadow mask adjacent thereto. In a method of manufacturing a foil shadow mask for use in a tension mask or a color cathode ray tube, the nickel content is about
0 to about 5 weight percent molybdenum, 0 to about 2 weight percent vanadium, 0 to about 2 weight percent titanium, 0 to about 2 weight percent hafnium, 0 to about 2 weight percent, Obtaining a hardened foil of an iron-nickel alloy containing at least one of about 2 weight percent niobium, the balance being iron and associated impurities, and heat treating the hardened foil to reduce the mask tension level by normal operation. A heat treatment to achieve the desired magnetic shielding properties while maintaining the hardness of the hardened material sufficiently tolerable, the foil mask may be heated to at least about 30 ° C. at a temperature above 400 ° C. and below the temperature at which the alloy forms a solid solution.
Heat treatment for a minute and adjust the cooling rate when said foil cools from said temperature to a temperature at which said alloy is substantially recrystallized, wherein the cooling rate is less than 5 ° C per minute, preferably less than 3 ° C per minute. Yes, the yield strength of the foil is 552N / mm ² (80ks
exceeds i), permeability exceeds 6,000, and coercive force is 199A / m
Obtaining a foil that is less than (2.5 Oersted);
A method for manufacturing a foil shadow mask, comprising: a step of applying tension to the foil; and a step of fixing the foil while applying tension to the support structure. 4. The method of claim 3, wherein the mask has a nickel content between about 75 and 85 weight percent, preferably about 80 weight percent,
A process according to claim 1, characterized in that the molybdenum content is between about 3 and 5% by weight, preferably about 4% by weight, with the balance being iron and associated impurities. 5. The method according to claim 3, wherein the foil is under a tension of at least 25 Newton / cm. 6. A method according to claim 3 or 4, wherein the faceplate has on its inner surface a centrally located deposited phosphor screen surface surrounded by a peripheral sealing surface adapted to fit the funnel. A shadow mask is fixed under tension to a frame-shaped shadow mask support structure on an inner surface of the face plate between the peripheral sealing surface and the screen surface, and the manufacturing method includes: Shaping the alloy into foil, perforating a central surface of the foil to form a foil mask that is sized to match the screen surface for color selection, and applying a tension of at least about 25 Newtons / cm. Applying the foil to the foil and aligning the tension frame with the face plate to position the foil repeatedly with the phosphor screen surface. Sequentially photo-screening the pattern of red, green and blue emitting phosphor deposits, applying tension to the foil mask, and positioning the holes with the pattern and position of the phosphor deposits. Fixing the foil mask to the mask support structure by mating; applying a paste-like devitrifying frit to the peripheral sealing surface to receive the funnel; and attaching the faceplate to the funnel. Forming a faceplate funnel assembly to heat the assembly to a temperature effective to devitrify the frit and permanently secure the funnel to the faceplate; Cooling the assembly at a cooling rate of less than about 3 to 5 ° C. per minute Heating the assembly and the foil, and that the cooling rate of the assembly and the foil is a low rate, partially annealing the foil mask, yield strength
Exceeds 552 N / mm ² (80 ksi), magnetic permeability exceeds about 6,000, coercive force is less than about 199 A / m (2.5 Newton / cm), and the coefficient of thermal expansion is almost equal to or more than the coefficient of thermal expansion of the face plate. A manufacturing method characterized by being effective in becoming 7. The method of claim 6, wherein the foil mask is heated at a temperature above 400 ° C. and less than the temperature at which the alloy forms a solid solution for at least about 30 minutes, and then the foil mask is heated at about 30 minutes per minute. A method of manufacturing, wherein the foil mask is tensioned by cooling to ambient temperature at a cooling rate of less than 3 to 5 ° C. 8. The method according to claim 6, wherein
The yield strength of the foil mask is about 1,033 N / mm ² (150 ksi)
, The permeability exceeds about 10,000, and the coercive force is about 80 A /
m (1.0 Oersted) or less.