WO1996015543A1 - DEFLECTION RING OF SINTERED MgZn-FERRITE MATERIAL, CATHODE RAY TUBE COMPRISING SUCH A RING AND MOULDING MADE FROM THIS MATERIAL - Google Patents
DEFLECTION RING OF SINTERED MgZn-FERRITE MATERIAL, CATHODE RAY TUBE COMPRISING SUCH A RING AND MOULDING MADE FROM THIS MATERIALInfo
- Publication number
- WO1996015543A1 WO1996015543A1 PCT/IB1995/000920 IB9500920W WO9615543A1 WO 1996015543 A1 WO1996015543 A1 WO 1996015543A1 IB 9500920 W IB9500920 W IB 9500920W WO 9615543 A1 WO9615543 A1 WO 9615543A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- ring
- deflection
- sintered
- mgzn
- cathode ray
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0206—Manufacturing of magnetic cores by mechanical means
- H01F41/0246—Manufacturing of magnetic circuits by moulding or by pressing powder
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/26—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on ferrites
- C04B35/2683—Other ferrites containing alkaline earth metals or lead
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
- H01J29/70—Arrangements for deflecting ray or beam
- H01J29/72—Arrangements for deflecting ray or beam along one straight line or along two perpendicular straight lines
- H01J29/76—Deflecting by magnetic fields only
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
- H01F41/06—Coil winding
- H01F41/071—Winding coils of special form
- H01F2041/0711—Winding saddle or deflection coils
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2229/00—Details of cathode ray tubes or electron beam tubes
- H01J2229/70—Electron beam control outside the vessel
- H01J2229/703—Electron beam control outside the vessel by magnetic fields
- H01J2229/7031—Cores for field producing elements, e.g. ferrite
Definitions
- cathode ray tube comprising such a ring and moulding made from this material.
- the invention relates to a deflection ring of sintered MgZn-ferrite material.
- the invention also relates to a cathode ray tube comprising such a deflection ring as well as to a moulding made from sintered MgZn-ferrite material.
- a deflection ring of the type mentioned in the opening paragraph is known per se.
- a description is given of a number of deflection rings which are made from an MgZn-ferrite material which also comprises a certain quantity of Li and Mn.
- a description is also given of a cathode ray tube comprising a deflection unit having such a deflection ring.
- the known deflection ring has disadvantages. It has been found that when this ring is used in a cathode ray tube, heat dissipation in the deflection unit occurs at room temperature, at induction levels of 20 to 25 mT and frequencies of 16 kHz or multiples thereof.
- the invention more particularly aims at providing a deflection ring as well as a cathode ray tube comprising a deflection unit, in which the heat-dissipation problem has been substantially reduced.
- a preferred embodiment of the deflection ring in accordance with the invention is characterized in that the average grain size of the material is 2.8 micrometers or less. Applicants have observed that at an average grain size of approximately 2.8 micrometers, approximately 90% of the grains have a monodomain structure. A smaller average grain size leads to a further increase of this percentage. Percentages of 98% and more are obtained if the average grain size of the MgZn-ferrite material ranges between 1.4 and 2.1 micrometers. The lowest heat dissipation is observed in deflection rings of sintered MgZn-ferrite material having this average grain size. It has been found that the manufacture of average grain sizes below 1.1 micrometers is relatively laborious and hence expensive.
- the size of the grains is defined in accordance with the so-called "mean linear intercept" method. It is noted that measurements on the known deflection rings of MgZn- ferrite material showed that the average grain size of this material is approximately 5.0 micrometers. Consequently, the majority of the grains of the known, sintered material do not have a monodomain structure. This is the reason why the known deflection rings exhibit a relatively high heat dissipation as compared to the deflection rings in accordance with the invention.
- the composition of the sintered material corresponds to the formula Mg j . 2 Zn 2 Fe 2 . y O 4 , wherein 0.1 ⁇ z ⁇ 0.4, 0.01 ⁇ y ⁇ 0.3.
- Deflection rings having this composition do not only exhibit a relatively low heat dissipation but also a relatively high saturation magnetization B s . Due to a Fe deficiency, the electrical resistance of the deflection ring is rather high. The highest magnetizations are obtained if the MgZn- ferrite material is composed so that 0.15 ⁇ z ⁇ 0.25 and 0.01 ⁇ y ⁇ 0.2.
- Another suitable deflection ring in accordance with the invention is characterized in that maximally 20 at. % of iron is replaced by trivalent manganese.
- all the iron present in the ferrite material is trivalent.
- the presence of a small quantity of divalent iron leads to a considerable reduction of the resistivity. This constitutes a major drawback.
- the presence of this small quantity of manganese ensures that all the iron present in the ferrite material is trivalent. If a small quantity of the trivalent ions in the material were reduced to divalent ions, first the more easily reducible trivalent manganese would be converted to divalent manganese.
- the reduction of manganese in the MgZn-ferrite material less seriously affects the properties of the inventive deflection ring than the reduction of iron.
- the MgZn-ferrite material in accordance with the invention may further be doped with small quantities of other elements, in particular sintering agents such as B 2 O 3 .
- the invention further relates to a moulding of a sintered MgZn-ferrite material. This is characterized in that the majority of the grains of the sintered material have a monodomain structure. Such a moulding has a low heat dissipation when the conditions under which it is used are such that the moulding is exposed to induction levels of 20 to 25 mT and frequencies of 16 kHz, or multiples thereof, at room temperature.
- the average grain size of the material is preferably 2.8 micrometers or less. The lowest dissipation is obtained if the average grain size of the material ranges between 1.45 and 2.1 micrometers. If the composition of the sintered material corresponds to the formula Mgj. 2 Zn 2 Fe 2 . y O 4 , wherein 0.1 ⁇ z ⁇ 0.4 and 0.01 ⁇ y ⁇ 0.3, the moulding exhibits a low heat dissipation as well as a relatively high saturation magnetization B s . By replacing maximally 20 at. % of iron by manganese, the reduction of the resistivity of the material due to a reduction of trivalent iron is avoided.
- transformers and inductors can particularly advantageously be used at relatively high frequencies of 1 MHz or more, and, preferably, at relatively high induction levels of 1 mT or more.
- the material can also very advantageously be used as an antenna rod in an induction lamp.
- the invention further relates to a cathode ray tube having a deflection unit which comprises a deflection ring.
- a deflection ring of sintered MgZn-ferrite material as described hereinabove is used in the cathode ray tube.
- Fig. 1 shows a deflection ring in accordance with the invention
- Fig. 2 is a schematic, sectional view of a cathode ray tube having a deflection unit comprising a deflection ring in accordance with the invention.
- Fig. 1-a is an elevational view of a deflection ring (1) in accordance with the invention.
- Fig. 1-b is a cross-sectional view of the deflection ring of Fig. 1-a, taken on the line I-b.
- the largest outside diameter of the ring on the side of the flared portion (2)
- the thickness of the deflection ring was 6 mm.
- the ring was made from a sintered MgZn-ferrite material, the average grain size of the material being 1.9 micrometers.
- the composition of the material corresponded to the formula Mg 0 8 Zn 0 2 Mn 0 Fe j 85 O 3 925 -
- a number of deflection rings having the above-mentioned composition and different average grain sizes were manufactured as follows.
- For the starting materials use was made of magnesium oxide (MgO), zinc oxide (ZnO), manganese oxide (Mn 2 O 3 ) and iron oxide (Fti ⁇ O j ).
- MgO magnesium oxide
- ZnO zinc oxide
- Mn 2 O 3 manganese oxide
- Fe oxide Fe ⁇ O j
- To obtain the above-mentioned composition 16.1 wt. % magnesium oxide, 8.4 wt. % zinc oxide, 4.2 wt. % manganese oxide (Mn 2 O 3 ) and 71.3 wt. % iron oxide were weighed and mixed in demineralised water for 6 hours. After filtration of the mixed powder, it was dried. Subsequently, the powder formed was prefixed at 850 °C for 4 hours.
- the fired product thus produced was subdivided into ten fractions, each of which was ground in a different manner in a liquid. All fractions 1-10 (see Table 1) were first ground with steel balls having a diameter of 13-16 mm for 12 hours. Fractions 1, 2, 3, 6, 7 and 10 were subsequently subjected to a further grinding operation with steel balls having a diameter of 3 mm for 3 hours. Fractions 4 and 8 were ground using these balls for 6 hours. Fractions 5 and 9 were ground using these balls for 9 hour. After filtering-off and drying, the average grain size of each of the fractions was determined by means of a Fisher measurement.
- each of the granulated fractions was pressed (600 kg/cm 2 ) to form deflection rings. These rings were sintered for approximately 2 hours at a maximum temperature ranging between 1120 and 1400 °C.
- the specific sinter temperature T of each of the fractions is mentioned in Table 1.
- the deflection rings of sintered MgZn-ferrite material had an average grain size ranging between 1.0 and 7.0 micrometers.
- the combination of shorter sinter times, lower sinter temperatures and longer grinding times results in sintered mouldings having a relatively small grain size.
- the average grain size was determined by means of the "mean linear intercept” method on the basis of scanning electron microscopy (SEM) and microstructure photographs.
- the average size of the magnetic domains was determined by means of neutron-polarization measurements.
- the sintered rings were subjected to a number of magnetic measurements such as the heat dissipation at room temperature, an induction level of 20 mT and a frequency of 32 kHz (P v -1), 64 kHz (P v -2) and 128 kHz (P v -3).
- the power losses of the rings were measured and indicated in table 1 as P v -4 (3 MHz and 10 mT) and P v -5 (5 MHz and 7.5 mT).
- the measured dissipation values P v (mW/cm 3 ) are listed in Table 1.
- the loss factor V (tan ⁇ / ⁇ ) is also indicated in Table 1 (5MHt).
- the Table shows that the rings having an average grain size of 2.8 micrometers or less exhibit a lower heat dissipation than rings having a larger average grain size. Rings having an average grain size d (micrometers) in the range from 1.45 to 2.1 micrometers were found to have the lowest heat dissipation.
- Rings of the different composition Mg 0 63 Zn 0 37 Mn 0 10 Fe 1>80 O 3#8 5 were also prepared by means of the above-mentioned method.
- Fig. 2 is a schematic longitudinal sectional view of a cathode ray tube (1).
- Said cathode ray tube comprises a cylindrical neck portion (2) and an adjoining funnel-shaped portion 3 whose front side (on the left in Fig. 2) is sealed by a display screen portion (4).
- the neck portion (3) accommodates an electrode system (5), shown schematically, by means of which one electron beam (in the case of a monochrome display tube) or three coplanar electron beams (in the case of a colour display tube) can be generated.
- a deflection unit (6) which surrounds the tube (1) coaxially is provided on the cathode ray tube (1) at the area where the neck portion merges with the funnel-shaped portion (3) of the tube.
- this unit comprises a first pair of saddle-shaped deflection coils (7, 7') for deflecting the electron beam(s) in the horizontal direction, a second pair of toroidal deflection coils (8, 8') for deflecting the electron beam(s) in the vertical direction and a deflection ring (9) which supports said pair of coils (8, 8').
- the shape of the deflection ring (9) and of the deflection coils is adapted to the funnel shape of the cathode ray tube (1).
- the deflection ring (9) of the cathode ray tube (1) is manufactured from a soft-magnetic MgZn-ferrite material, the majority of the grains of the sintered material having a monodomain structure.
- the tube in accordance with the invention is heated to a lesser degree than a tube which comprises the deflection ring in accordance with the state of the art.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Ceramic Engineering (AREA)
- Power Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Magnetic Ceramics (AREA)
Abstract
The invention relates to a deflection ring of sintered MgZn-ferrite material. In accordance with the invention, this deflection ring is characterized in that the majority of the grains of the sintered material have a monodomain structure. By virtue thereof, a relatively small heat dissipation occurs in the ring when it is used in a cathode ray tube. The average grain size of the sintered MgZn-ferrite material is preferably 2.8 micrometers or less. MgZn-ferrite materials whose composition corresponds to the formulaMg1-zZnzFe2-yO4, wherein 0.1 < z < 0.4 and 0.01 < y < 0.3, have the additional advantage that they have a relatively high saturation magnetization and a relatively high electrical resistance. The invention also relates to a cathode ray tube comprising the above-mentioned deflection ring and to a moulding made from the above-mentioned MgZn-ferrite material.
Description
Deflection ring of sintered MgZn-ferrite material, cathode ray tube comprising such a ring and moulding made from this material.
The invention relates to a deflection ring of sintered MgZn-ferrite material. The invention also relates to a cathode ray tube comprising such a deflection ring as well as to a moulding made from sintered MgZn-ferrite material.
A deflection ring of the type mentioned in the opening paragraph is known per se. For example, in United States Patent US 5,057,738, filed by Applicants, a description is given of a number of deflection rings which are made from an MgZn-ferrite material which also comprises a certain quantity of Li and Mn. In this Patent Document, a description is also given of a cathode ray tube comprising a deflection unit having such a deflection ring. The known deflection ring has disadvantages. It has been found that when this ring is used in a cathode ray tube, heat dissipation in the deflection unit occurs at room temperature, at induction levels of 20 to 25 mT and frequencies of 16 kHz or multiples thereof. This dissipation leads to an undesirable increase of the temperature of the tube and hence to a reduction of the life of the surrounding electronic components of the tube. It is an object of the invention to obviate the above-mentioned disadvantage. The invention more particularly aims at providing a deflection ring as well as a cathode ray tube comprising a deflection unit, in which the heat-dissipation problem has been substantially reduced.
These and other objects of the invention are achieved by means of a deflection ring of the type mentioned in the opening paragraph, which is characterized in that the majority of the grains of the sintered material have a monodomain structure.
In series of experiments which have led to the present invention, Applicants have established that the magnetic structure of the grains is of great importance for the dissipation properties of the relevant deflection ring. Experiments have shown, for example, that sintered MgZn-ferrite materials having grains which comprise only one magnetic domain exhibit a surprisingly low heat dissipation. This applies in particular under the above-mentioned measuring conditions at induction levels of 20 to 25 mT and frequencies of 16 kHz, or multiples thereof, at room temperature. Under said conditions, the dissipation can be reduced by 20% or more. It is noted that the expression "the majority of the grains"
is to be understood to mean herein "at least 90% of the grains". Further, it is noted that grains having a monodomain structure comprise only one magnetic domain.
A preferred embodiment of the deflection ring in accordance with the invention is characterized in that the average grain size of the material is 2.8 micrometers or less. Applicants have observed that at an average grain size of approximately 2.8 micrometers, approximately 90% of the grains have a monodomain structure. A smaller average grain size leads to a further increase of this percentage. Percentages of 98% and more are obtained if the average grain size of the MgZn-ferrite material ranges between 1.4 and 2.1 micrometers. The lowest heat dissipation is observed in deflection rings of sintered MgZn-ferrite material having this average grain size. It has been found that the manufacture of average grain sizes below 1.1 micrometers is relatively laborious and hence expensive. In addition, these small grain sizes do not lead to a further reduction of the dissipation because the favourable monodomain structure has already been reached. The size of the grains is defined in accordance with the so-called "mean linear intercept" method. It is noted that measurements on the known deflection rings of MgZn- ferrite material showed that the average grain size of this material is approximately 5.0 micrometers. Consequently, the majority of the grains of the known, sintered material do not have a monodomain structure. This is the reason why the known deflection rings exhibit a relatively high heat dissipation as compared to the deflection rings in accordance with the invention.
Another favourable embodiment of the deflection ring in accordance with the invention is characterized in that the composition of the sintered material corresponds to the formula Mgj.2Zn2Fe2.yO4, wherein 0.1 < z < 0.4, 0.01 < y < 0.3. Deflection rings having this composition do not only exhibit a relatively low heat dissipation but also a relatively high saturation magnetization Bs. Due to a Fe deficiency, the electrical resistance of the deflection ring is rather high. The highest magnetizations are obtained if the MgZn- ferrite material is composed so that 0.15 < z < 0.25 and 0.01 < y < 0.2.
Another suitable deflection ring in accordance with the invention is characterized in that maximally 20 at. % of iron is replaced by trivalent manganese. Preferably, all the iron present in the ferrite material is trivalent. The presence of a small quantity of divalent iron leads to a considerable reduction of the resistivity. This constitutes a major drawback. The presence of this small quantity of manganese ensures that all the iron present in the ferrite material is trivalent. If a small quantity of the trivalent ions in the material were reduced to divalent ions, first the more easily reducible trivalent manganese
would be converted to divalent manganese. The reduction of manganese in the MgZn-ferrite material less seriously affects the properties of the inventive deflection ring than the reduction of iron. It is also advantageous to replace a part of the magnesium by lithium and/or nickel. This replacement enhances the saturation magnetisation of the deflection ring. The MgZn-ferrite material in accordance with the invention may further be doped with small quantities of other elements, in particular sintering agents such as B2O3.
The invention further relates to a moulding of a sintered MgZn-ferrite material. This is characterized in that the majority of the grains of the sintered material have a monodomain structure. Such a moulding has a low heat dissipation when the conditions under which it is used are such that the moulding is exposed to induction levels of 20 to 25 mT and frequencies of 16 kHz, or multiples thereof, at room temperature.
The average grain size of the material is preferably 2.8 micrometers or less. The lowest dissipation is obtained if the average grain size of the material ranges between 1.45 and 2.1 micrometers. If the composition of the sintered material corresponds to the formula Mgj.2Zn2Fe2.yO4, wherein 0.1 < z < 0.4 and 0.01 < y < 0.3, the moulding exhibits a low heat dissipation as well as a relatively high saturation magnetization Bs. By replacing maximally 20 at. % of iron by manganese, the reduction of the resistivity of the material due to a reduction of trivalent iron is avoided. By virtue of the favourable, low heat dissipation of the inventive moulding, it is very interesting to apply said moulding in transformers and inductors. It has been found that such transformers and inductors can particularly advantageously be used at relatively high frequencies of 1 MHz or more, and, preferably, at relatively high induction levels of 1 mT or more. The material can also very advantageously be used as an antenna rod in an induction lamp.
The invention further relates to a cathode ray tube having a deflection unit which comprises a deflection ring. In accordance with the invention, a deflection ring of sintered MgZn-ferrite material as described hereinabove, is used in the cathode ray tube. By virtue thereof, excessive heating of the cathode ray tube in operation is precluded, so that the resultant reduction of the life of the surrounding electronic components and the problems caused thereby are precluded.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
In the drawings:
Fig. 1 shows a deflection ring in accordance with the invention,
Fig. 2 is a schematic, sectional view of a cathode ray tube having a deflection unit comprising a deflection ring in accordance with the invention. Fig. 1-a is an elevational view of a deflection ring (1) in accordance with the invention. Fig. 1-b is a cross-sectional view of the deflection ring of Fig. 1-a, taken on the line I-b. The largest outside diameter of the ring (on the side of the flared portion (2)) was 86 mm and the smallest diameter (on the side of the neck (3)) was 54 mm. The thickness of the deflection ring was 6 mm. The ring was made from a sintered MgZn-ferrite material, the average grain size of the material being 1.9 micrometers. The composition of the material corresponded to the formula Mg0 8Zn0 2Mn0 Fej 85O3 925-
A number of deflection rings having the above-mentioned composition and different average grain sizes were manufactured as follows. For the starting materials use was made of magnesium oxide (MgO), zinc oxide (ZnO), manganese oxide (Mn2O3) and iron oxide (Fti^Oj). To obtain the above-mentioned composition, 16.1 wt. % magnesium oxide, 8.4 wt. % zinc oxide, 4.2 wt. % manganese oxide (Mn2O3) and 71.3 wt. % iron oxide were weighed and mixed in demineralised water for 6 hours. After filtration of the mixed powder, it was dried. Subsequently, the powder formed was prefixed at 850 °C for 4 hours.
To obtain sintered deflection rings having different grain sizes, the fired product thus produced was subdivided into ten fractions, each of which was ground in a different manner in a liquid. All fractions 1-10 (see Table 1) were first ground with steel balls having a diameter of 13-16 mm for 12 hours. Fractions 1, 2, 3, 6, 7 and 10 were subsequently subjected to a further grinding operation with steel balls having a diameter of 3 mm for 3 hours. Fractions 4 and 8 were ground using these balls for 6 hours. Fractions 5 and 9 were ground using these balls for 9 hour. After filtering-off and drying, the average grain size of each of the fractions was determined by means of a Fisher measurement.
After mixing said fractions with a binder (2% ammonium algimate in demineralised water) the mixture obtained was passed through a sieve and subsequently granulated. Next, each of the granulated fractions was pressed (600 kg/cm2) to form deflection rings. These rings were sintered for approximately 2 hours at a maximum temperature ranging between 1120 and 1400 °C. The specific sinter temperature T of each of the fractions is mentioned in Table 1. Dependent upon the sinter duration, sinter temperature and the fineness of the grind, the deflection rings of sintered MgZn-ferrite material had an average grain size ranging between 1.0 and 7.0 micrometers. The combination of shorter
sinter times, lower sinter temperatures and longer grinding times results in sintered mouldings having a relatively small grain size. The average grain size was determined by means of the "mean linear intercept" method on the basis of scanning electron microscopy (SEM) and microstructure photographs. The average size of the magnetic domains was determined by means of neutron-polarization measurements.
The sintered rings were subjected to a number of magnetic measurements such as the heat dissipation at room temperature, an induction level of 20 mT and a frequency of 32 kHz (Pv-1), 64 kHz (Pv-2) and 128 kHz (Pv-3). The power losses of the rings were measured and indicated in table 1 as Pv-4 (3 MHz and 10 mT) and Pv-5 (5 MHz and 7.5 mT). The measured dissipation values Pv (mW/cm3) are listed in Table 1. The loss factor V (tan δ/μ) is also indicated in Table 1 (5MHt). The Table shows that the rings having an average grain size of 2.8 micrometers or less exhibit a lower heat dissipation than rings having a larger average grain size. Rings having an average grain size d (micrometers) in the range from 1.45 to 2.1 micrometers were found to have the lowest heat dissipation.
TABLE 1
no. d T Pv-1 P -2 Pv-3 P -4 Pv-5 vαo-6)
1 1.1 1150 13.0 22.0 44.0 858 938 115
2 1.45 1200 12.0 24.3 41.0 1065 1071 134
3 1.75 1250 12.5 22.3 39.0 946 1009 140
4 1.90 1250 11.0 21.5 40.1 958 1057 136
5 2.11 1250 12.0 22 44.2 973 1065 143
6 2.27 1275 14.0 24.0 45.3 964 1053 145
7 2.81 1300 16.0 27.0 57.0 1122 1094 222
8 3.14 1300 19.0 35.0 70.1 1246 1391 323
9 3.53 1300 19.5 36.0 67.0 1464 1554 359
10 6.95 1350 18.0 37.8 68.4 1472 1551 330
Rings of the different composition Mg0 63Zn0 37Mn0 10Fe1>80O3#85 were also prepared by means of the above-mentioned method. The average grain size d, the maximum sintering temperature T (°C) and the power-losses P (mW/cm3) measured at
f = 3 MHz and β = 10 mT, are indicated in Table 2. Also in this case, it holds that the rings having an average grain size less than 28 show the lowest losses.
TABLE 2
d T
1.05 1200 843
1.35 1250 1033
1.39 1250 898
2.05 1250 912
2.31 1275 924
2.82 1275 1036
3.34 1300 1385
3.82 1300 1437
5.52 1350 1453
Fig. 2 is a schematic longitudinal sectional view of a cathode ray tube (1).
Said cathode ray tube comprises a cylindrical neck portion (2) and an adjoining funnel-shaped portion 3 whose front side (on the left in Fig. 2) is sealed by a display screen portion (4). The neck portion (3) accommodates an electrode system (5), shown schematically, by means of which one electron beam (in the case of a monochrome display tube) or three coplanar electron beams (in the case of a colour display tube) can be generated. A deflection unit (6) which surrounds the tube (1) coaxially is provided on the cathode ray tube (1) at the area where the neck portion merges with the funnel-shaped portion (3) of the tube. In this case, this unit comprises a first pair of saddle-shaped deflection coils (7, 7') for deflecting the electron beam(s) in the horizontal direction, a second pair of toroidal deflection coils (8, 8') for deflecting the electron beam(s) in the vertical direction and a deflection ring (9) which supports said pair of coils (8, 8'). As is shown in this Figure, the shape of the deflection ring (9) and of the deflection coils is adapted to the funnel shape of the cathode ray tube (1).
The deflection ring (9) of the cathode ray tube (1) is manufactured from a soft-magnetic MgZn-ferrite material, the majority of the grains of the sintered material
having a monodomain structure. By virtue thereof, the tube in accordance with the invention is heated to a lesser degree than a tube which comprises the deflection ring in accordance with the state of the art.
Claims
1. A deflection ring of sintered MgZn-ferrite material, characterized in that the majority of the grains of the sintered material have a monodomain structure.
2. A deflection ring as claimed in Claim 1, characterized in that the average grain size of the material is 2.8 micrometers or less.
3. A deflection ring as claimed in Claim 2, characterized in that the average grain size of the material ranges between 1.45 and 2.1 micrometers. 4. A deflection ring as claimed in any one of the preceding Claims, characterized in that the composition of the sintered material corresponds to the formula Mgj.2Zn2Fe2.yO4, wherein 0.1 < z < 0.
4 and 0.01 < y < 0.3. 5. A deflection ring as claimed in Claim 4, characterized in that maximally
15 at. % of iron is replaced by trivalent manganese.
6. A cathode ray tube having a deflection unit which comprises a deflection ring as claimed in any one of the preceding Claims.
7. A moulding of sintered MgZn-ferrite material, characterized in that the majority of the grains of the sintered material have a monodomain structure.
8. A moulding as claimed in Claim 7, characterized in that the average grain size of the material is 2.8 micrometers or less.
9. A moulding as claimed in Claim 8, characterized in that the average grain size of the material ranges between 1.45 and 2.1 micrometers.
10. A moulding as claimed in any one of Claims 7, 8 or 9, characterized in that the composition of the sintered material corresponds to the formula Mg .2Zn2Fe2.yO4, wherein 0.1 < z < 0.4 and 0.01 < y <0.3.
11. A moulding ring as claimed in Claim 10, characterized in that maximally
15 at. % of iron is replaced by manganese.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8515873A JPH09507960A (en) | 1994-11-09 | 1995-10-25 | Deflection rings made of sintered MgZn ferrite material, cathode ray tubes equipped with such rings and molded articles made of such materials |
DE69523035T DE69523035T2 (en) | 1994-11-09 | 1995-10-25 | DEFLECTING RING MADE OF Sintered MGZN FERRITE MATERIAL, CATHODE RAY TUBE WITH SUCH A RING AND SHAPED BODY MADE OF THIS MATERIAL |
EP95933594A EP0738422B1 (en) | 1994-11-09 | 1995-10-25 | DEFLECTION RING OF SINTERED MgZn-FERRITE MATERIAL, CATHODE RAY TUBE COMPRISING SUCH A RING AND MOULDING MADE FROM THIS MATERIAL |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP94203263 | 1994-11-09 | ||
EP94203263.2 | 1994-11-09 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1996015543A1 true WO1996015543A1 (en) | 1996-05-23 |
Family
ID=8217362
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IB1995/000920 WO1996015543A1 (en) | 1994-11-09 | 1995-10-25 | DEFLECTION RING OF SINTERED MgZn-FERRITE MATERIAL, CATHODE RAY TUBE COMPRISING SUCH A RING AND MOULDING MADE FROM THIS MATERIAL |
Country Status (5)
Country | Link |
---|---|
US (2) | US5841225A (en) |
EP (1) | EP0738422B1 (en) |
JP (1) | JPH09507960A (en) |
DE (1) | DE69523035T2 (en) |
WO (1) | WO1996015543A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN109454869B (en) * | 2018-09-28 | 2020-07-24 | 长春理工大学 | Pointolite multiplication scanning printing device for large-size photosensitive 3D printing |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4372865A (en) * | 1980-09-26 | 1983-02-08 | Spang Industries, Inc. | Carbonate/hydroxide coprecipitation process |
US5057738A (en) * | 1989-05-26 | 1991-10-15 | U.S. Philips Corporation | Soft magnetic mgmnzn-ferrite material, deflection ring manufactured from said material, and as a cathode-ray tube comprising a deflection coil having such a deflection ring |
EP0624886A1 (en) * | 1993-05-11 | 1994-11-17 | Koninklijke Philips Electronics N.V. | Sintered transformer or inductor core of NiZn ferrite material |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL175473C (en) * | 1972-06-20 | 1984-11-01 | Matsushita Electric Ind Co Ltd | FERRITE CORE FOR A MAGNETIC HEAD AND METHOD FOR MANUFACTURING A FERRITE CORE. |
JPS58140324A (en) * | 1982-02-10 | 1983-08-20 | Japan Metals & Chem Co Ltd | Manufacture of ferrite as starting material |
NL8403282A (en) * | 1984-10-30 | 1986-05-16 | Philips Nv | TITANIC AND COBALT-CONTAINING MANGANESE-ZINC FERRITE CORE AND METHOD OF MANUFACTURING THE SAME |
EP0210699B1 (en) * | 1985-07-30 | 1991-05-02 | Koninklijke Philips Electronics N.V. | Deflection unit having a thin-walled yoke ring for cathode-ray tubes |
JPH0513981A (en) * | 1991-06-28 | 1993-01-22 | Mitsubishi Electric Corp | Cathode ray tube display device |
-
1995
- 1995-10-25 EP EP95933594A patent/EP0738422B1/en not_active Expired - Lifetime
- 1995-10-25 WO PCT/IB1995/000920 patent/WO1996015543A1/en active IP Right Grant
- 1995-10-25 DE DE69523035T patent/DE69523035T2/en not_active Expired - Fee Related
- 1995-10-25 JP JP8515873A patent/JPH09507960A/en not_active Ceased
- 1995-11-07 US US08/553,229 patent/US5841225A/en not_active Expired - Fee Related
-
1998
- 1998-03-04 US US09/034,440 patent/US5932819A/en not_active Expired - Fee Related
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4372865A (en) * | 1980-09-26 | 1983-02-08 | Spang Industries, Inc. | Carbonate/hydroxide coprecipitation process |
US5057738A (en) * | 1989-05-26 | 1991-10-15 | U.S. Philips Corporation | Soft magnetic mgmnzn-ferrite material, deflection ring manufactured from said material, and as a cathode-ray tube comprising a deflection coil having such a deflection ring |
EP0624886A1 (en) * | 1993-05-11 | 1994-11-17 | Koninklijke Philips Electronics N.V. | Sintered transformer or inductor core of NiZn ferrite material |
Also Published As
Publication number | Publication date |
---|---|
EP0738422A1 (en) | 1996-10-23 |
EP0738422B1 (en) | 2001-10-04 |
DE69523035D1 (en) | 2001-11-08 |
US5841225A (en) | 1998-11-24 |
JPH09507960A (en) | 1997-08-12 |
US5932819A (en) | 1999-08-03 |
DE69523035T2 (en) | 2002-07-11 |
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