MXPA00006217A - Masking device for a colour flat screen cathode ray tube comprising a supporting frame for planar mask and planar mask - Google Patents

Abstract

A device for masking a flat screen color monitor has a mask mounted within and tensioned at ambient temperature by a support. The support is an iron nickel alloy with a thermal expansion coefficient ? 5 x 10<-6>/K between 20 - 150 degrees C and an elastic limit Rp0.2 at 20 degrees C ? 700 MPa. Independent claims are included for the following:(a) Methods of manufacturing the above device including hardening of the screen at 400 - 800 degrees C. (b) Methods of manufacturing the above device including de-tensioning the screen at 400 - 600 degrees C.

Description

DEMASCARAMIEN DEVICE OR FOR CATHODIC TUBE FLAT DISPLAY COLOR DISPLAY, TYPE COMPRISING A SUPPORT FRAMEWORK FOR MASK SHADOW TENSE AND SHADING MASK TENSA Description of the invention The present invention relates to a masking device for flat screen color display cathode tube, of the type comprising a support frame for a tense shadow mask and a tense shadow mask mounted on the support frame. The cathodic color display tubes include, in a known manner, a display screen provided with photophores, an electron gun that produces three electron beams and a masking device, consisting of a shadow mask mounted on a support frame, placed in front of the display screen and intended to ensure a good quality of the displayed image. The shadow mask is constituted by a metal sheet perforated by a plurality of holes or windows through which the three electron beams pass to excite the REF.121311 photophores placed on the screen. The quality of the image obtained is the better the more accurate the alignment between the photophores, the holes of the shadow mask and the electron beams. When the display tube is in operation, a significant part of the electron beams is intercepted by the shadow mask, which generates local warming of the latter, which can deform and therefore deteriorate the quality of the displayed image. In addition, the quality of the image can also be impaired by the vibrations of the shadow mask, caused by the various sources of vibration. To obtain images of good quality, the shadow mask on the one hand, must be little sensitive to local heating, and on the other hand, have an adequate frequency of vibration, high enough so that the amplitude of these vibrations does not disturb the color of the images by a misalignment of the electron beams, the holes in the shadow mask and the photophores. When the display screen is domed or convex, the shadow mask has a shape that adopts that of the screen, and the problems of sensitivity to local heating and vibration are resolved by developing the shadow mask by embossing an alloy sheet Fe-Ni with very low coefficient of expansion, perforated with holes. The shadow mask is simply welded onto a support frame that exerts no effort on the shadow mask. The frame can therefore be light, which has advantages. When the display screen is flat, the shadow mask can be a non-embossed or embossed sheet, fixed for example by welding on a previously compressed support frame which then exerts a tension on the shadow mask. The shadow mask is therefore called "tense". The tension of the shadow mask is intended, on the one hand, to solve the problem of sensitivity to local heating, and on the other hand to increase the frequency of vibration of the shadow mask, to attenuate the amplitude of these vibrations . This solution mainly involves the use of a material whose characteristics allow to maintain a sufficient tension in the operating temperature domain of the cathode tube (approximately 100 ° C), and this after a heating of approximately 500 ° C during the manufacture of the cathodic tube . In effect, the shadow mask is mounted taut on its support frame, then the assembly is placed on the cathode tube which is subsequently sealed at a temperature of approximately 500 ° C for one hour. This heating can cause a creep of the shadow mask and its frame that can loosen the shadow mask. To make a tense shadow mask and its support frame, it has been proposed to use a weakly alloyed steel (ie, containing, in general, less than 5% alloying elements). Although the coefficient of thermal expansion of this steel is high, the tension of the shadow mask must be greater than 200 MPa to avoid deformations due to local heating. This solution leads to a heavy frame, e the weight can reach, if not surpass, 6 kg. In order to produce a taut shadow mask and its supporting frame, it has also been proposed to produce the Fe-Ni alloy shadow mask with a small expansion coefficient and the steel frame. But it is then necessary to provide means to avoid causing overvoltages of the shadow mask during the sealing of the tube at 500 ° C, in the absence of which, the shadow mask is broken or torn during this operation. The object of the present invention is to remedy these drawbacks by proposing a means for manufacturing a taut shadow mask. and its support frame, which are not very sensitive to local heating, have a suitable frequency of suitable vibration, and which supports the sealing operation of the tube at elevated temperature. For this purpose, the object of the invention is a masking device for a flat screen color cathodic display tube, of the type comprising a support frame for a tense shadow mask, and a tense shadow mask mounted on the support frame. , so as to be subjected to a voltage at room temperature. The support frame for a tense shadow mask is a hardened Fe-Ni alloy that has a coefficient of thermal expansion between 20 ° C and 150 ° C lower than 5 x 10"6 / K and an elasticity limit Rp0.2 a 20 ° C higher than 700 MPa, and the taut shadow mask is an alloy of Fe-Ni that has a coefficient of thermal expansion between 20 ° C and 150 ° C lower than 5 x 10"6 / K. The hardened Fe-Ni alloy of which the support frame is constituted can be, for example, a Fe-Ni alloy with "hardening" type structural hardening. »Whose chemical composition is such as (in% by weight): 40.5% <; Ni + Co + Cu < 44.5% 0% < Colt; 5% 0% < Cu < 3% 1.5% < Ti = 3.5% 0.05% < To < 1% C = 0.05% Si = 0.5% Mn = 0.5% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration. The hardened Fe-Ni alloy of which the support frame is formed can also be a Fe-Ni alloy of the "hardened with carbides" type having a chemical composition such as (in% by weight). 36% < Ni + Co + Cu < 40% 0% = Co < 5% 0% < Cu < 3% 1.6% < Mo = 2.8% 0.4% < Cr < 1.5% 0.15% < C < 0.35% Yes < 0.5% Mn < 0.5% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration. The hardened Fe-Ni alloy of which the support frame is formed can also be a Fe-Ni alloy of the "beryllium hardened" type having a chemical composition such as (in% by weight): 34% < Ni + Co + Cu < 38% 0% < Co = 5% 0% = Cu < 3% 0.15% < Be < 1% C < 0.05% Yes < 0.5% Mn < 1% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration. The hardened Fe-Ni alloy of which the support frame is formed can also be a Fe-Ni alloy of the "hardened solid solution" type having a chemical composition such as (in% by weight): 38% < Ni + Co + Cu < 42% 0% < Colt; 5% 0% < Cu < 3% 1% < Nb < 4% C = 0.05% Yes < 0.5% Mn < 0.5% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration. Preferably, the shadow mask is a Fe-Ni alloy whose coefficient of thermal expansion between 20 ° C and 150 ° C is less than 2 x 10 ~ 6 / K and whose chemical composition can comprise (in% by weight): 32 % < Ni < 37% 0% < Colt; 5.5% 0% < Mn < 0 5% S i < 0 2% C < 0 02% S < 0 0 1% P < 0 02% being the rest iron and impurities resulting from the elaboration. The tension of the shadow mask is therefore preferably less than 120 MPa. The shadow mask may also be a hardened Fe-Ni alloy of the "hardened" type, of the "hardened hardened" type of the "beryllium hardened" type or of the "hardened solid solution" type, as defined above. . The tension of the shadow mask can then be greater than 150 MPa. The invention also relates to a process for the manufacture of a shadow mask support frame, of a masking device for flat screen color display cathodic tube, the shadow mask support frame of which is a Fe- Nor "hardened?" According to this process, a "hardened" Fe-Ni alloy band is used »Annealed or annealed and cold-hardened and then de-stressed, whereby a blank part of the frame is cut, folded and welded, then the raw part of the frame is subjected to a hardening heat treatment at a temperature between 600 ° C and 800 ° C for a time between 30 minutes and 2 hours. The invention also relates to a process for the manufacture of the shadow mask support frame of a masking device for flat screen color cathodic tube, where the support frame of the shadow mask is an alloy Fe -Ni «hardened with carbides». According to this process, the support frame of the shadow mask is manufactured by cutting, folding and welding a strip of Fe-Ni alloy «hardened with carbides», obtained by cold rolling with a higher stacking and welding ratio at 50%, and by means of a hardening heat treatment at a temperature comprised between 650 ° C and 850 ° C for 1 minute to 2 hours, possibly followed by a complementary cold rolling with a stacking and welding ratio of less than 70% and of a thermal stressing treatment at a temperature between 400 ° C and 600 ° C.

When the Fe-Ni alloy is of the "beryllium hardened" type, the cold rolling is carried out with a stacking and welding ratio, between 20% and 80%, and the hardening treatment is a maintenance between 400 ° C and 700 ° C for a time between 1 minute and 8 hours. When the Fe-Ni alloy is of the "hardened by solid solution" type, the cold rolling is carried out with a stacking and welding ratio of between 20% and 70%, and the thermal treatment is a deceleration corresponding to a maintenance between 400 ° C and 600 ° C. It should be noted that, instead of being made by cutting and folding a band, the frame can be manufactured by joining tubes of square, triangular or round section. The hardening heat treatment is carried out either before the assembly of the frame, or later. The invention will now be described in more detail and illustrated with the examples, but in a non-limiting manner, with respect to the attached figures in which: Figure 1 schematically represents a masking device for cathodic tube. Flat screen color display, - Figure 2 shows the expansion curves between 20 ° C and 600 ° C of Fe-Ni and steel alloys. The masking device for flat screen color cathodic display tube, shown in FIG. 1, comprises a shadow mask 1 consisting of a perforated sheet with a plurality of holes 2, and a support frame 3 that includes the side uprights 4 (only one is observed in the figure) and the end posts 5 and 5 '. The shadow mask 1 is fixed, for example, by welding on the upper edges 6 and 6 'of the end posts 5 and 5'. At the time of assembly, the support frame 3 is subjected to compression stresses (small arrows in Figure 1) intended to generate an elastic deformation that reduces the spacing of the end posts 5 and 5 ', and the shadow mask is subjected to tensile stresses (thick arrows in figure 1) intended to generate an elastic deformation of elongation. The shadow mask is then fixed by welding on the support frame, and the compressive and tensile stresses are suppressed. However, the elastic deformations of the support frame and the shadow mask remain, even if the shadow mask is subjected to tension. The device consisting of the support frame and shadow mask is then mounted on the cathode tube and this is sealed at a temperature close to 500 ° C for about 1 hour. The heating in the vicinity of 500 ° C generates a dilation of the support frame and the shadow mask, which can either increase the tension of the shadow mask if the support frame dilates more than the shadow mask, or either maintain the tension if the dilatations are identical, or reduce the tension if the support frame dilates less than the shadow mask. When the tension remains significant, it generates a deformation by creep of the support frame (reduction of the length) and of the shadow mask (increase of the length). After returning to room temperature, these creep deformations overlap the initial elastic deformations, although the tension of the shadow mask is reduced. When the creep deformations are sufficiently weak, the residual tension of the shadow mask is sufficient for the adequate frequency of the shadow mask vibration to be satisfactory, and to induce at any point an elastic deformation that allows absorbing the resulting dilatations of the mask. local warming and thus prevent the shadow mask from being deformed under the effect of these local warming. In a first embodiment, the shadow mask is composed of a Fe-Ni alloy whose coefficient of thermal expansion between 20 ° C and 150 ° C is less than 2 x 10"6 / K, and the support frame is elaborated of hardened Fe-Ni alloy, which has a coefficient of thermal expansion between 20 ° C and 150 ° C lower than 5 x 10 ~ 6 / K, an elasticity limit Rp0.2 at 20 ° C higher than 700 MPa and an elongation by creep at 500 ° C lower than 0.01%, under a constraint of 300 MPa The alloy of which the shadow mask is constituted, has a chemical composition comprising, by weight: 32% <; Ni < 37% 0% < Colt; 5.5% 0% < Mn < 0.5% Yes < 0.2% C < 0.02% S < 0.01% P < 0.02%, the remainder being iron and impurities resulting from the elaboration. This alloy is, for example, either an alloy containing from 35% to 37% nickel, less than 0.4%, or better still less than 0.1%, manganese and not cobalt, or an alloy containing 32% 34% nickel, 3.5% to 5.5% cobalt and less than 0.1% manganese. This alloy can be used in the annealed state above 750 ° C after cold rolling, to have an elasticity limit between 260 MPa and 300 MPa, and a creep elongation at 500 ° C lower than 0.02% under a constraint of 50 MPa. In this case, the tension of the shadow mask should, preferably, not generate in the recorded area of the shadow mask, a constraint higher than 60 MPa, which, taking into account the small expansion coefficient, is sufficient for minimize the effects of local heating. The alloy can also be used in the cold-hardened state, or better still, cold-hardened and de-stressed; in this first case, mainly, the tension of the shadow mask can reach 120 MPa. Such a tension can make it possible to improve the vibrational behavior of the shadow mask. The hardened Fe-Ni alloy of which the support frame is constituted is, for example, either an alloy of the "hardened" type, or an alloy of the "hardened with carbide" type, or of the "hardened" type. with beryllium ", or of the" hardened by solid solution "type. The chemical composition of a "hardened" type alloy »Comprises, for example, in% by weight: 40.5% < Ni + Co + Cu < 44.5% - 0% < Colt; 5% 0% < Cu < 3% 1.5% = Ti < 3.5% 0.05% < To < 1% C < 0.05% Yes < 0.5% Mn < O .5% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration. The proportion of nickel is chosen to obtain a satisfactory coefficient of thermal expansion. A part of the nickel can be replaced by cobalt or copper, although these elements are given optionally and their proportions can be zero. The titanium and the aluminum allow to obtain a structural hardening by homogeneous and coherent precipitation of the phase? Ni3 (Ti, Al). When the alloy used is of the type "hardened ?' »The support frame of the shadow mask is manufactured from a thickness band comprised, for example, between 0.5 mm and 3 mm, obtained by cold rolling and annealing at a temperature comprised, preferably, between 900 ° C and 1100 ° C. After annealing, the band may eventually undergo a complementary cold rolling with a stacking and welding ratio of less than 30%, followed by a deceleration to the parade fast enough to avoid the precipitation of the phase? at a temperature between 400 ° C and 600 ° C. In order to manufacture the shadow mask support frame, pieces are cut out in the band which are shaped, for example by bending, and assembled or fixed by welding, by screwing, by riveting, or by any other means, so as to get a rough piece of support frame. The blank of the support frame is then subjected to a thermal treatment of precipitation hardening, consisting of a maintenance at a temperature comprised between 600 ° C and 800 ° C for a time comprised between 30 minutes and 2 hours. The frame can also be manufactured by trimming, with formation and assembly of a previously annealed and hardened band by heat treatment to the parade, between 700 ° C and 850 ° C for 1 to 15 minutes, or by static thermal treatment between 600 ° C and 800 ° C for a time between 30 minutes and 2 hours. In this case, the heat treatment is carried out on a band directly exiting from the cold rolling.

In both cases, the hardening heat treatment allows obtaining an elasticity limit Rp0.2 higher than 700 MPa. By way of example, with an alloy of the "hardened? R" type whose chemical composition comprises (in% by weight): after treatment by hardening at 700 ° C for 1 hour, carried out on an annealed strip 900 ° C for 30 minutes after cold rolling, the following mechanical characteristics are obtained: yield strength Rp 0. 2: 8 60 MPa tensile strength Rm: 1 1 5 6 MPa uniform elongation Au: 1 3. 8% total elongation At: 1 7. 1 % The coefficient of thermal expansion of this alloy is 3.4 x 10_6 / K between 20 ° C and 150 ° C. The chemical composition of an alloy of the "hardened with carbides" type comprises, for example, in% by weight: 36% < Ni + Co + Cu < 40% 0% < Co = '5% 0% < Cu < 3% 1.6% < Mo < 2.8% 0.4% < Cr < 1.5% 0.15% < C < 0.35% Yes < 0.5% Mn < 0.5% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration. The proportion of nickel is chosen to obtain a coefficient of thermal expansion between 20 ° C and 150 ° C lower than 5 x 10_6 / K. Nickel can be partially replaced by cobalt or copper, although these elements are optional. Molybdenum, chromium and carbon allow the formation of carbides that harden the structure. With this alloy, the support frame is manufactured by cutting, folding and assembling by welding, riveting, screwing or any other means, a strip obtained by cold rolling with a stacking and welding ratio comprised between 60% and 80%, followed by a hardening heat treatment that can be performed during the parade for 1 to 15 minutes between 750 ° C and 850 ° C, or in static form for 15 minutes to 2 hours, between 650 ° C and 750 ° C. Eventually, after the hardening heat treatment, the belt can undergo a complementary cold rolling with a stacking and welding rate of less than 70%, followed by a thermal treatment of deceleration between 400 ° C and 600 ° C, for 30 seconds at 5 minutes. The strip obtained in this way has a yield strength greater than 700 MPa and an elongation at break greater than 5%, sufficient to allow forming by bending. By way of example, with an alloy of the "hardened with carbides" type having the following chemical composition (in% by weight): After the cold rolling with a stacking and welding ratio of 70% and thermal treatment of hardening to the parade at 800 ° C for 1 to 2 minutes, the following mechanical characteristics are obtained: yield strength Rp0.2: 766 MPa resistance to the traction Rm: 922 MPa elongation distributed Au: 14.8% elongation total At: 15.1% The coefficient of thermal expansion between 20 ° C and 150 ° C is 3.7 x 10"6 / K. When a complementary cold rolling is carried out with a stacking and welding ratio of 30% and a de-stressing is carried out at 700 ° C for 1 to 2 minutes, the following characteristics: elasticity limit Rp0.2: 1013 MPa tensile strength Rm: 1090 MPa distributed elongation Au: 7.9% total elongation At: 11.6% the coefficient of thermal expansion between 20 ° C and 150 ° C is 2.8 x 10"6 / K. The chemical composition of an alloy of the "beryllium hardened" type includes, for example,% by weight: 34% < Ni + Co + Cu < 38% 0% < Colt; 5% 0% < Cu < 3% 0.15% = Be < 1% C = 0.05% If < 0.5% Mn < 1% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration. With this alloy, the support frame is manufactured by cutting, folding and assembling by welding, riveting, screwing or any other means, a strip obtained by cold rolling with a stacking and welding ratio comprised between 20% and 80%, followed by a hardening heat treatment consisting of a maintenance between 400 ° C and 700 ° C for 1 minute to 8 hours. By way of example, with an alloy of the "hardened with beryllium" type having the following chemical composition (in% by weight): after the cold rolling with a stacking and welding ratio of 70% and thermal treatment of hardening at 550 ° C for 1 hour, the following mechanical characteristics are obtained: yield point Rp 0. 2: 84 3 MPa tensile strength Rm: 9 1 6 MPa total elongation At: 4. 2% The chemical composition of an alloy of the type "hardened by solid solution", comprises, for example, in% by weight: 38% < Ni + Co + Cu < 42% 0% < Colt; 5% 0% < Cu < 3% 1% < Nb < 4% C < 0.05% Yes < 0.5% Mn < 0.5% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration. With this alloy, the support frame is manufactured by cutting, folding and assembling by welding, riveting, screwing or any other means, a strip obtained by cold rolling with a rate or proportion of stacking and welding comprised between 20% and 70%. %, followed by a thermal treatment of detensioning consisting of maintenance between 400 ° C and 600 ° C. By way of example, with an alloy of the type "hardened by solid solution" having the following chemical composition (in% by weight): after the cold rolling with a stacking and welding ratio of 33% and thermal treatment of deceleration at 550 ° C for 1 minute, the following mechanical characteristics are obtained: yield strength Rp 0. 2: 8 04 MPa tensile strength Rm: 9 68 MPa total elongation At: 8. 1% The use of alloys with a small coefficient of expansion makes it possible to obtain a good compatibility between the shadow mask and its support frame, in particular to avoid a very important variation of the tension of the shadow mask when the temperature varies, due to differential dilatations.

The elasticity limit Rp0.2 at 20 ° C higher than 700 MPa and the very good resistance to creep at 500 ° C, allow to manufacture a light frame since the constraints to which these elements are subjected can be high. The lightness of the support frame favors a weak sensitivity of the masking device to temperature variations. The good resistance to creep of the alloys of which the shadow mask and the supporting frame is constituted, allows maintaining a satisfactory mask mask voltage, after heating in the vicinity of 500 ° C intended to seal the screen slab on the glass cone of the cathode tube, and this even more when the voltage sought for the mask shade is not very high. On the other hand, and as the curves of Figure 2 show, while the average coefficient of expansion between 20 ° C and 150 ° C of the alloy of which the shadow mask is constituted (curve 10, FeNi alloy) is weaker than that of the alloy of which the support frame is constituted (curve 11, hardened FeNi alloy), the average expansion coefficients between 20 ° C and 500 ° C are close. This is favorable. In fact, at 500 ° C the dilation of the support frame is close to that of the shadow mask, the tension of the shadow mask is close to the tension created in the assembly. On the contrary, between 100 ° C and 150 ° C, that is, at the operating temperatures of the shadow mask, the voltage is increased due to the fact of the expansion differential, and this leads to a decrease in the sensitivity to heating local, and especially to reduce the sensitivity to vibrations. By way of comparison, curve 12 of FIG. 2, related to a weakly alloyed steel, shows that the expansion differential between this steel and the Fe-Ni alloy with a small coefficient of expansion is such that if the support frame were constituted steel and the Fe-Ni alloy shadow mask with small coefficient of expansion, in the absence of adapted compensation means, the heating carried out at the time of sealing the cathode tube would lead to the breaking of the shadow mask.

In a second embodiment, the support frame is made, as in the first embodiment, of hardened Fe-Ni alloy, for example of the "hardened and" type of the "hardened with carbides" type, of the type « hardened with beryllium »or of the« hardened by solid solution »type. But the shadow mask itself is also composed of a hardened Fe-Ni alloy, for example of the "hardened?" Type, of the "hardened with carbide" type, of the "beryllium hardened" type or of the "hardened by solid solution" type. »As described above. In this case, the hardening treatment is carried out before the chemical etching of the shadow mask. The shadow mask is then mounted on the support frame with a tension that can be higher than 150 MPa, even higher than 200 MPa (but this tension must be less than 300 MPa), which allows to increase the own frequency of vibration or to reduce the thickness of the shadow mask. Such a tension of the shadow mask is made possible by the tensile and creep strength characteristics of the alloy with structural hardening which are substantially higher than those of the annealed Fe-Ni alloy used in the first embodiment .

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention is that it is clear from the present description of the invention.

Claims (15)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A masking device for flat screen color display cathodic tube, of the type comprising a support frame for a tense shadow mask, and a tense shadow mask mounted on the support frame, so as to be subject to tension at room temperature, characterized in that: the support frame is a hardened Fe-Ni alloy having a coefficient of thermal expansion between 20 ° C and 150 ° C lower than 5 x 10 ~ 6 / K, and an elasticity limit Rp0 .2 at 20 ° C higher than 700 MPa, the taut shadow mask is a hardened Fe-Ni or Fe-Ni alloy having a coefficient of thermal expansion between 20 ° C and 150 ° C lower than 5 x 10_6 / K.

2. The device according to claim 1, characterized in that the hardened Fe-Ni alloy of which the support frame is constituted, is a Fe-Ni alloy of the "hardened and" type whose chemical composition comprises, by weight: 40.5 % < Ni + Co + Cu < ^ 44.5% 0% < Colt; 5% 0% < Cu < 3% 1.5% < You < 3.5% 0.05% < To < 1% C < 0.05% Yes < 0.5% Mn < 0.5% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration.

3. The device according to claim 1, characterized in that the hardened Fe-Ni alloy of which the support frame is constituted, is a Fe-Ni alloy of the "hardened with carbides" type whose chemical composition comprises, by weight: 36% < Ni + Co + Cu < 40% 0% < Colt; 5% 0% < Cu < 3% 1.6% < Mo < 2.8% 0.4% < Cr < 1.5% 0.15% < C < 0.35% Yes < 0.5% Mn = 0.5% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration.

4. The device according to claim 1, characterized in that the hardened Fe-Ni alloy of which the support frame is constituted, is a Fe-Ni alloy of the "beryllium hardened" type whose chemical composition comprises, by weight: 34% < Ni + Co + Cu < 38% 0% < Colt; 5% 0% < Cu < 3% 0.15% < Be < 1% C < 0.05% Yes < 0.5% Mn < 1% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration.

5. The device according to claim 1, characterized in that the hardened Fe-Ni alloy of which the support frame is constituted, is a Fe-Ni alloy of the "hardened by solid solution" type whose chemical composition comprises, by weight: % < Ni + Co + Cu < 42% 0% < Colt; 5% 0% < Cu < 3% 1% < Nb < 4% C < 0.05% Yes 0.5% Mn < 0.5% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration.

6. The device according to any of claims 1 to 5, characterized in that the shadow mask is a Fe-Ni alloy whose coefficient of thermal expansion between 20 ° C and 150 ° C is less than 2 x 10 ~ 6 / K.

7. The device according to claim 6, characterized in that the chemical composition of the alloy of which the shadow mask is constituted comprises, by weight: 32% < Ni < 37% 0% < Colt; 5.5% 0% < Mn < 0.5% Yes < 0.2% C < 0.02% S < 0.01% P = 0.02%, the remainder being iron and impurities resulting from processing.

8. The device according to any of claims 1 to 5, characterized in that the tension of the shadow mask is greater than 150 MPa and because the chemical composition of the alloy of which the shadow mask is constituted comprises, by weight: 40.5% < Ni + Co + Cu < 44.5% - 0% < Colt; 5% 0% < Cu < 3% 1.5% < You < 3.5% 0.05% < To < 1% C < 0.05% Yes < 0.5% Mn < 0.5% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration.b.

9. The device according to any of claims 1 to 5, characterized in that the tension of the shadow mask is greater than 150 MPa and because the chemical composition of the alloy of which it is constituted • the shadow mask comprises, by weight: 36% < Ni + Co + Cu < 40% 0% < Colt; 5% 0% < Cu < 3% 1.6% < Mo < 2.8% 0.4% < Cr < 1.5% 0.15% < C < 0.35% Yes < 0.5% Mn < 0.5% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration.

10. The device according to any of claims 1 to 5, characterized in that the tension of the shadow mask is greater than 150 MPa and because the chemical composition of the alloy of which the shadow mask is constituted comprises, by weight: 34% < Ni + Co + Cu < 38% 0% < Co = 5% 0% < Cu = 3% 0.15% < Be < 1% C = 0.05% If < 0.5% Mn < 1% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration.

11. The device according to any of claims 1 to 5, characterized in that the tension of the shadow mask is greater than 150 MPa and because the chemical composition of the alloy of which the shadow mask is constituted comprises, by weight: 38% < Ni + Co + Cu < 42% 0% < Colt; 5% 0% < Cu < 3% 1% < Nb < 4% C < 0.05% Yes < 0.5% Mn < 0.5% S < 0.01% P < 0.02%, the rest being iron and impurities resulting from the elaboration.

12. A process for the manufacture of a device according to claim 2, characterized in that a strip of Fe-Ni alloy with structural hardening, annealed or annealed and cold hardened is used to manufacture the shadow mask support frame and then When the frame is de-stressed, a rough part of the frame is made by cutting, folding and assembling the Fe-Ni alloy strip of the "hardened?" type, then the frame blank is subjected to a hardening heat treatment at a temperature between 600 ° C and 800 °, for a time between 30 minutes and 2 hours.

13. A. process for the manufacture of a device according to claim 3, characterized in that a band of Fe-Ni alloy of the "hardened with carbides" type with a rate or proportion of stacking and welding greater than 50%, the cold rolled strip is subjected to a hardening heat treatment, either carried out at the runway at a temperature between 750 ° C and 850 ° C for 1 to 15 minutes, or in static form at a temperature between 650 ° C and 750 ° C for 15 minutes to 2 hours, optionally, a complementary cold rolling is carried out with a rate or proportion of stacking and welding less than 70% followed by a thermal treatment of de-stressing to a temperature between 400 ° C and 600 ° C for 30 seconds to 5 minutes, and the support frame of the shadow mask is manufactured by trimming, folding and assembling the gives.

14. A process for the manufacture of a device according to claim 4, characterized in that a strip of Fe-Ni alloy of the "beryllium-hardened" type with a cold-rolled strip is cold rolled to manufacture the shadow mask support frame. stacking and welding ratio between 20% and 80%, the cold-rolled strip is subjected to a hardening heat treatment at a temperature between 400 ° C and 700 ° C for 1 minute to 8 hours, and the frame is manufactured of the shadow mask support by trimming, folding and assembling the band.

15. A process for the manufacture of a device according to claim 5, characterized in that a strip of Fe-Ni alloy of the "hardened by solid solution" type with a high proportion is cold rolled to manufacture the frame of the shadow mask. of stacking and welding comprised between 20% and 70%, the cold-rolled strip is subjected to a thermal treatment of de-tensioning at a temperature between 400 ° C and 600 ° C, and the frame of the shadow mask support is manufactured by cutting, folding and assembling the band.