All The Claims

1. A digital content encryption method, wherein:
an encryption apparatus divides digital content into a plurality of areas, and respectively assigns session keys different from one another to the areas generated by the division;
the session keys assigned to the respective areas are used for encrypting the areas concerned;
a pair of a public key and a private key according to public-key cryptography is assigned to each set of at least one user who uses the digital content that has been encrypted, each pair of the public key and the private key being different from other pairs;
for each area, the session key assigned to that area is encrypted with the public key assigned to the set of at least one user who is permitted to browse the area in question; and
encrypted digital content comprising the plurality of encrypted areas and the encrypted session keys, at least one of which is generated for each areas, is outputted.
2. A digital content encryption method according to claim 1, wherein:
header information of the encrypted digital content includes, as partitioning information, information indicating dividing positions of the digital content, and information indicating which user can decrypt which encrypted area in the encrypted digital content.
3. A digital content encryption method according to claim 1, wherein:
at least one same user is included in a plurality of the sets each formed of at least one user.
4. A digital content encryption method according to claim 1, wherein:
in cases in which an inclusive relation between the user and the at least one set is expressed by associating the user with a leaf of a tree and by associating the at least one set to which the user belongs with a node and a root of the tree, a key management apparatus assigns a public key and a private key corresponding to the public key to the leaf, the node and the root, with each pair of a public key and a private key being different from other pairs;
different private keys assigned respectively to a leaf corresponding to one user, the root, and nodes existing on a path connecting the leaf and the root, are delivered as decryption keys to the user corresponding to the leaf; and
the public keys corresponding to the private keys delivered to the user are made public as encryption keys corresponding to the decryption keys.
5. A digital content encryption method according to claim 1, wherein:
the encryption apparatus generates a digital signature corresponding to the encrypted areas, or to the encrypted areas and the encrypted session keys, and gives the generated digital signature to the encrypted areas, or to the encrypted areas and the encrypted session keys.
6. A digital content decryption method for digital content that has been encrypted according to the method of claim 1, wherein:
a decryption apparatus uses a private key, provided from the user to the decryption apparatus, to decrypt the session key that has been encrypted with the public key corresponding to the private key, and uses the decrypted session key to decrypt the area that has been encrypted with the session key; and
displays the decrypted area, and displays blacked out the areas that are not decrypted by the decryption apparatus.
7. A digital content decryption method for digital content that has been encrypted according to claim 5, wherein:
the decryption apparatus validates the given digital signature to examine whether the encrypted digital content has been altered or not.
8. A workflow system comprising an encryption apparatus and a plurality of decryption apparatuses, wherein:
the encryption apparatus divides digital content into a plurality of areas depending on kinds of information;
the encryption apparatus comprises a means which encrypts the areas of the divided digital content with encryption keys different for each area; and
each of the decryption apparatuses comprises: a means which decrypts a specific area of the encrypted digital content, and further comprises a means which transmits the encrypted digital content to another decryption apparatus.
9. A workflow system according to claim 8, wherein:
the workflow system comprises a key management apparatus that has a function of distributing suitable decryption keys to the decryption apparatuses depending on users of the decryption apparatuses; and
the key management apparatus comprises a means which makes public encryption keys corresponding to the decryption keys, to the encryption apparatus.
10. A workflow system according to claim 8, wherein:
the encryption apparatus has a function of giving digital signature to the encrypted digital content; and
each of the decryption apparatuses has a function of examining whether the digital content has been altered or not, by validating the encrypted digital content given the digital signature.
11. An encryption method according to claim 1, wherein:
the encryption apparatus constructs, for each user, a session key set including session keys used for encrypting respective areas that can be browsed by the user in question; and
the encryption apparatus encrypts the session key sets for each user, using the public key according to the public-key cryptography, assigned to each user.
12. An encryption method according to claim 11, wherein:
the encryption apparatus generates an order control random value for a first user;
the encryption apparatus encrypts a first session key set constructed for the first user and the order control random value generated for the first user, using the public key according to the public-key cryptography assigned to the first user; and
a result of the encryption is taken as an order control random value for a second user, and the order control random value is used for encrypting a second session key set for the second user, the second session key set being different from the first session key set.
13. A decryption method corresponding to the encryption method according to claim 12, wherein:
a decryption apparatus:
decrypts the order control random value of the second user, using a private key provided from the second user to the decryption apparatus;
divides a result of the decryption into the order control random value of the first user and the second session key set;
decrypts areas that have been encrypted with session keys obtained from the second session key set; and
generates the encrypted digital content from the order control random value of the first user and the encrypted areas.
14. An encryption method according to claim 12, wherein:
a plurality of second order control random values are generated by applying threshold secret sharing processing to the order control random value;
the session keys are encrypted with respect to each of the second order control random values;
a set of results of the encryption of the session keys is taken as the order control random value for the second user.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.

1. A nitride semiconductor device comprising:
a stacked foundation layer formed on an AlN buffer layer formed on a silicon substrate, the stacked foundation layer including a plurality of AlN foundation layers and a plurality of GaN foundation layers being alternately stacked with the AlN foundation layers; and
a functional layer including:
a low-concentration part provided on the stacked foundation layer, the low-concentration part including a nitride semiconductor and having a Si concentration less than 1\xd71018 cm\u22123; and
a high-concentration part provided on the low-concentration part and having a Si concentration not less than 1\xd71018 cm\u22123,

a substrate-side GaN foundation layer closest to the silicon substrate among the plurality of GaN foundation layers including:
a first portion having a Si concentration less than 5\xd71018 cm\u22123;
a second portion having a Si concentration less than 5\xd71018 cm\u22123; and
a third portion being provided between the first portion and the second portion, the third portion having a Si concentration not less than 5\xd71018 cm\u22123 and having a thickness smaller than a sum of a thickness of the first portion and a thickness of the second portion.
2. The device according to claim 1, wherein
the thickness of the third portion is not less than 0.1 nanometers and not more than 50 nanometers.
3. The device according to claim 1, wherein
all of the GaN foundation layers except for the substrate-side GaN foundation layer among the plurality of GaN foundation layers have a Si concentration less than 5\xd71018 cm\u22123.
4. The device according to claim 1, wherein
a thickness of the high-concentration part is not less than 1.5 micrometers and not more than 4 micrometers.
5. The device according to claim 1, wherein
the functional layer further includes:
a light emitting part provided on the high-concentration part and having a plurality of barrier layers and a plurality of well layers, the each of the well layers being provided between the barrier layers; and
a p-type semiconductor layer provided on the light emitting part, the p-type semiconductor layer including a nitride semiconductor and containing at least one of Mg, Zn and C.
6. A nitride semiconductor device comprising
a functional layer formed on an AlN buffer layer formed on a silicon substrate, the functional layer including:
a plurality of low-concentration parts including a nitride semiconductor and having a Si concentration less than 5\xd71018 cm\u22123; and
a plurality of high-concentration parts having a Si concentration not less than 5\xd71018 cm\u22123, the low-concentration parts being alternately stacked with the high-concentration parts,

a thickness of each of the high-concentration parts being smaller than a thickness of each of the low-concentration parts,
each of the high-concentration parts includes Si\u03b1N\u03b2(0<\u03b1, 0<\u03b2).
7. The device according to claim 6, wherein
the thickness of each of the high-concentration parts is not less than 0.1 nanometers and not more than 50 nanometers.
8. The device according to claim 6, further comprising
a stacked foundation layer formed on the AlN buffer layer and under the functional layer,
the stacked foundation layer including a plurality of AlN foundation layers and a plurality of GaN foundation layers being alternately stacked with the AlN foundation layers, and
a substrate-side GaN foundation layer closest to the silicon substrate among the plurality of GaN foundation layers including:
a first portion having a Si concentration less than 5\xd71018 cm\u22123;
a second portion having a Si concentration less than 5\xd71018 cm\u22123;and
a third portion provided between the first portion and the second portion, the third portion having a Si concentration not less than 5\xd71018 cm\u22123 and having a thickness smaller than a sum of a thickness of the first portion and a thickness of the second portion.
9. A nitride semiconductor wafer comprising:
a silicon substrate;
an AlN buffer layer provided on the silicon substrate;
a stacked foundation layer provided on the AlN buffer layer, the stacked foundation layer including a plurality of AlN foundation layers and a plurality of GaN foundation layers being alternately stacked with the AlN foundation layers; and
a functional layer including
a low-concentration part provided on the stacked foundation layer, the low-concentration part including a nitride semiconductor and having a Si concentration less than 5\xd71018 cm\u22123, and
a high-concentration part provided on the low-concentration part and having a Si concentration not less than 5\xd71018 cm\u22123,

a substrate-side GaN foundation layer closest to the silicon substrate among the plurality of GaN foundation layers including:
a first portion having a Si concentration less than 5\xd71018 cm\u22123;
a second portion having a Si concentration less than 5\xd71018 cm\u22123; and
a third portion provided between the first portion and the second portion, the third portion having a Si concentration not less than 5\xd71018 cm\u22123 and having a thickness smaller than a sum of a thickness of the first portion and a thickness of the second portion.
10. The wafer according to claim 9, wherein
the thickness of the third portion is not less than 0.1 nanometers and not more than 50 nanometers.
11. The wafer according to claim 9, wherein
all of the GaN foundation layers except for the substrate-side GaN foundation layer among the plurality of GaN foundation layers have a Si concentration less than 5\xd71018 cm\u22123.
12. The wafer according to claim 9, wherein
a thickness of the high-concentration part is not less than 1.5 micrometers and not more than 4 micrometers.
13. The wafer according to claim 9, wherein
the functional layer further includes:
a light emitting part provided on the high-concentration part and having a plurality of barrier layers and a plurality of well layers, the each of the well layers being provided between the barrier layers; and
a p-type semiconductor layer provided on the light emitting part, the p-type semiconductor layer including a nitride semiconductor and containing at least one of Mg, Zn and C.
14. A nitride semiconductor wafer comprising:
a silicon substrate;
an AlN buffer layer provided on the silicon substrate; and
a functional layer provided on the AlN buffer layer,
the functional layer including:
a plurality of low-concentration parts including a nitride semiconductor and having a Si concentration less than 5\xd71018 cm\u22123; and
a plurality of high-concentration parts having a Si concentration not less than 5\xd71018 cm\u22123, the low-concentration parts being alternately stacked with the high-concentration parts,

a thickness of each of the high-concentration parts is smaller than a thickness of each of the low-concentration parts,
each of the high-concentration parts includes Si\u03b1N\u03b2(0<\u03b1, 0<\u03b2).
15. The wafer according to claim 14, wherein
the thickness of each of the high-concentration parts is not less than 0.1 nanometers and not more than 50 nanometers.
16. The wafer according to claim 14, further comprising
a stacked foundation layer formed on the AlN buffer layer and under the functional layer,
the stacked foundation layer including a plurality of AlN foundation layers and a plurality of GaN foundation layers being alternately stacked with the AlN foundation layers, and
a substrate-side GaN foundation layer closest to the silicon substrate among the plurality of GaN foundation layers including:
a first portion having a Si concentration less than 5\xd71018 cm\u22123;
a second portion having a Si concentration less than 5\xd71018 cm\u22123;and
a third portion provided between the first portion and the second portion, the third portion having a Si concentration not less than 5\xd71018 cm\u22123 and having a thickness smaller than a sum of a thickness of the first portion and a thickness of the second portion.
17. A method for manufacturing a nitride semiconductor layer comprising:
forming a stacked foundation layer by alternately stacking a plurality of AlN foundation layers and a plurality of GaN foundation layers on an AlN buffer layer provided on a silicon substrate; and
forming a functional layer by forming a low-concentration part on the stacked foundation layer and forming a high-concentration part on the low-concentration part, the low-concentration part including a nitride semiconductor and having a Si concentration less than 5\xd71018 cm\u22123, the high-concentration part having a Si concentration not less than 5\xd71018 cm\u22123,
in formation of a substrate-side GaN foundation layer closest to the silicon substrate among the plurality of GaN foundation layers, the forming the stacked foundation layer includes forming
a first portion having a Si concentration less than 5\xd71018 cm\u22123,
a second portion having a Si concentration less than 5\xd71018 cm\u22123 and
a third portion provided between the first portion and the second portion, the third portion having a Si concentration not less than 5\xd71018 cm\u22123 and having a thickness smaller than a sum of a thickness of the first portion and a thickness of the second portion.
18. The method according to claim 17, wherein
the thickness of the third portion is not less than 0.1 nanometers and not more than 50 nanometers.
19. A method for manufacturing a nitride semiconductor layer comprising:
forming a functional layer on an AlN buffer layer formed on a silicon substrate,
the forming the functional layer including repeating a process a plurality of times, the process including:
forming a low-concentration part including a nitride semiconductor and having a Si concentration less than 5\xd71018 cm\u22123; and
forming a high-concentration part having a Si concentration not less than 5\xd71018 cm\u22123, and
a thickness of each of the high-concentration parts is smaller than a thickness of each of the low-concentration parts,
each of the high-concentration parts includes Si\u03b1N\u03b2(0<\u03b1, 0<\u03b2).
20. The method according to claim 19, wherein
the thickness of each of the high-concentration parts is not less than 0.1 nanometers and not more than 50 nanometers.
21. The device according to claim 1, wherein the third portion includes Si\u03b1N\u03b2(0<\u03b1, 0<\u03b2).
22. The wafer according to claim 9, wherein the third portion includes Si\u03b1N\u03b2(0<\u03b1, 0<\u03b2).
23. The wafer according to claim 17, wherein the third portion includes Si\u03b1N\u03b2(0<\u03b1, 0<\u03b2).
24. The device according to claim 6, wherein the thickness of each of the low-concentration parts is not less than 50 nanometers and not more than 500 nanometers.
25. The device according to claim 6, wherein the thickness of each of the low-concentration parts is not less than 300 nanometers and not more than 500 nanometers.
26. The wafer according to claim 14, wherein the thickness of each of the low-concentration parts is not less than 50 nanometers and not more than 500 nanometers.
27. The wafer according to claim 14, wherein the thickness of each of the low-concentration parts is not less than 300 nanometers and not more than 500 nanometers.
28. The method according to claim 19, wherein the thickness of each of the low-concentration parts is not less than 50 nanometers and not more than 500 nanometers.
29. The method according to claim 19, wherein the thickness of each of the low-concentration parts is not less than 300 nanometers and not more than 500 nanometers.

1. In a photopolymerizable resin composition for sandblast resist, which includes an aqueous alkali-soluble binder polymer, a photopolymerizable oligomer, a photoinitiator, and an additive,
the photopolymerizable oligomer comprising at least one of a polyalkylene glycol mono(meth)acrylate compound having a terminal alkyl group as selected from the group consisting of compounds represented by the following formulas I to IV, or a polyalkylene glycol di(meth)acrylate compound as selected from the group consisting of compounds represented by the following formulas V to VIII,
wherein R1 is hydrogen or methyl; R2 is an alkyl group having 1 to 30 carbon atoms; and m is an integer from 1 to 30,
wherein R1, R2 and m are as defined in the formula I; and n is an integer from 1 to 30, where n+m is equal to an integer from 2 to 50,
wherein R1, R2, m and n are as defined in the formula II, where n+m is equal to an integer from 2 to 50,
wherein R1, R2, m and n are as defined in the formula II; and x is an integer from 1 to 30, where m+n+x is equal to an integer from 6 to 30,
wherein R1 is hydrogen or methyl; m is an integer from 1 to 30; and n is an integer from 1 to 30, where m+n is equal to an integer from 3 to 4 40,
wherein R1, m and n are as defined in the formula V, where m+n is equal to an integer from 3 to 40,
wherein R1, m and n are as defined in the formula V; and 1 is an integer from 1 to 30, where l+m+n is equal to an integer from 3 to 50,
wherein R1, m, n and 1 are as defined in the formula VII; and p is an integer from 1 to 30, where l+m+n+p is equal to an integer from 4 to 40.
2. The photopolymerizable resin composition for sandblast resist as claimed in claim 1, wherein the weight ratio of the aqueous alkali-soluble polymer compound to the photopolymerizable oligomer is 70:30 to 5:95.
3. The photopolymerizable resin composition for sandblast resist as claimed in claim 1, wherein the photoinitiator is included in an amount of 2 to 10 wt. % with respect to the total weight of the photopolymerizable resin composition.
4. The photopolymerizable resin composition for sandblast resist as claimed in claim 1, wherein the photopolymerizable oligomer further comprises 0.01 to 50 wt. % of a plasticizer based on the solid part of the photopolymerizable resin composition.
5. The photopolymerizable resin composition for sandblast resist as claimed in claim 4, wherein the plasticizer is at least one selected from phthalic esters such as dibutyl phthalate, diheptyl phthalate, dioctyl phthalate, or diallyl phthalate; glycol esters such as triethylene glycol diacetate, or tetraethylene glycol diacetate; acid amides such as p-toluene sulfon amide, benzene sulfon amide, or N-n-butyl-benzene sulfon amide; aliphatic dibasic acid esters such as diisopropyl adiphate, dioctyl azelate, or dibutyl maleate; phosphates such as triphenyl phosphate; and tributyl citrate, glycerol triacetate, or dioctyl butyl lauryl 4,5-diepoxycyclohexane-1,2-dicarboxylate.
6. In a photopolymerizable resin composition for sandblast resist, which includes an aqueous alkali-soluble polymer compound, a photopolymerizable oligomer, a photoinitiator, and an additive, the photopolymerizable oligomer comprising a mixture of at least one of a polyalkylene glycol mono(meth)acrylate compound having a terminal alkyl group as selected from compounds represented by the following formulas I to IV, a polyalkylene glycol di(meth)acrylate compound selected from compounds represented by the following formulas V to VIII, and at least one of urethane compounds having a terminal (meth)acrylate group as represented by the following formula IX and derived from a polyether or polyester compound having a terminal hydroxyl group, a diisocyanate compound and a (meth)acrylate compound having a hydroxyl group,
wherein R1 is hydrogen or methyl; R2 is an alkyl group having 1 to 30 carbon atoms; and m is an integer from 1 to 30,
wherein R1, R2 and m are as defined in the formula I; and n is an integer from 1 to 30, where n+m is equal to an integer from 2 to 50,
wherein R1, R2, m and n are as defined in the formula II, where n+m is equal to an integer from 2 to 50,
wherein R1, R2, m and n are as defined in the formula II; and x is an integer from 1 to 30, where m+n+x is equal to an integer from 6 to 30,
wherein R1 is hydrogen or methyl; m is an integer from 1 to 30; and n is an integer from 1 to 30, where m+n is equal to an integer from 3 to 34 40,
wherein R1, m and n are as defined in the formula V, where n+m is equal to an integer from 2 to 50,
wherein R1, m and n are as defined in the formula V; and 1 is an integer from 1 to 30, where l+m+n is equal to an integer from 3 to 50,
wherein R1, m, n and 1 are as defined in the formula VII; and p is an integer from 1 to 30, where l+m+n+p is equal to an integer from 4 to 40,
wherein R1 and R are the same or different and include hydrogen or methyl; R3 is alkylene or alkylene ether; R4 is a divalent residual group derived by removing a urethane compound having a terminal (meth)acrylate group as derived from a diisocyanate derivative of two isocyanate groups; R5 is a divalent residual group derived by removing a diol derivative of a hydroxyl group, the diol derivative having a terminal hydroxyl group and a polyether or polyester as the structure of a main chain thereof; and q is an integer from 1 to 10.
7. The photopolymerizable resin composition for sandblast resist as claimed in claim 6, wherein the weight ratio of the aqueous alkali-soluble polymer compound to the photopolymerizable oligomer is 70:30 to 5:95.
8. The photopolymerizable resin composition for sandblast resist as claimed in claim 6, wherein the photoinitiator is included in an amount of 2 to 10 wt. % with respect to the total weight of the photopolymerizable resin composition.
9. The photopolymerizable resin composition for sandblast resist as claimed in claim 6, wherein the photopolymerizable oligomer further comprises 0.01 to 50 wt. % of a plasticizer based on the solid part of the photopolymerizable resin composition.
10. The photopolymerizable resin composition for sandblast resist as claimed in claim 9, wherein the plasticizer is at least one selected from phthalic esters such as dibutyl phthalate, diheptyl phthalate, dioctyl phthalate, or diallyl phthalate; glycol esters such as triethylene glycol diacetate, or tetraethylene glycol diacetate; acid amides such as p-toluene sulfon amide, benzene sulfon amide, or N-n-butyl-benzene sulfon amide; aliphatic dibasic acid esters such as diisopropyl adiphate, dioctyl azelate, or dibutyl maleate; phosphates such as triphenyl phosphate; and tributyl citrate, glycerol triacetate, or dioctyl butyl lauryl 4,5-diepoxycyclohexane-1,2-dicarboxylate.
11. The photopolymerizable resin composition for sandblast resist as claimed in claim 6, wherein the photopolymerizable resin composition comprises, based on 100 parts by weight of the compound represented by the formula IX, 5 to 70 parts by weight of a compound represented by the formulas I to IV, or the formulas V to VIII.

The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.

What is claims is:

1. A bearing device comprising a shaft, a housing, a double row of bearings provided between the shaft and the housing and preloaded by a fixed-position preloading method, the double row of bearings having a pair of races with a gap therebetween for preload adjustment, and the bearing device further having a support member for supporting one side of the races in the pre-loading direction, and the support member provided on the side of one of the shaft and the housing.
2. A bearing device comprising a shaft, a housing, a double row of bearings provided between the shaft and the housing and preloaded by a fixed-position preloading method, the double row of bearings having a first and second races with a gap therebetween for preload adjustment, and the bearing device further having a support member for supporting one side surface of the first race in the pre-loading direction, and the support member provided on the side of one of the shaft and the housing, and wherein the first race and the second race have a width, respectively, such that the width of the first race is smaller than the width of the second race, and at least the second race is fitted and fixed with adhesion to one of the shaft and the housing.
3. A bearing device comprising a shaft, a housing, a double row of ball bearings provided between the shaft and the housing and preloaded by a fixed-position preloading method, the double row of ball bearings having a row of balls, respectively, the balls in one of the rows displaced from the balls in the other row in the radial direction of the ball bearings, the double row of ball bearings having a first and second inner races and a first and second outer races, the first inner race having a radially inner section on the side of the shaft and a radially outer section with a raceway, such that the width of the radially inner section is smaller than the width of the radially outer section, and the second outer race having a radially outer section on the side of the housing and a radially inner section with a raceway, such that the width of the radially outer section is smaller than the width of the radially inner section, and wherein the radially outer section of the first inner race is located radially outside the radially inner section of the second outer race.
4. A bearing device of claim 3, wherein the rows of the balls are spaced from each other by a distance in the axial direction between the centers of the balls, such that the distance in the axial direction is up to the diameter of the balls, and wherein the rows of balls have a pitch circle, such that the difference in diameter between the pitch circle of one of the rows of balls and the pitch circle of the other row of balls is at least twice the diameter of the balls.
5. A bearing device of one of claims 3 and 4, wherein the width of the first inner race is larger than the width of the second inner race, such that the radially inner section of the first inner race is pressed on the radially outer section of the second inner race.
6. A bearing device comprising a pair of outer races each having an inner peripheral surface on which an outer ring raceway is formed, a pair of inner races each having an outer peripheral surface on which an inner ring raceway is formed, a plurality of balls rotatably provided between the outer ring raceway and the inner ring raceway, a retainer provided between the inner peripheral surface of the respective outer races and the outer peripheral surface of the respective inner races to rotatably hold the balls, the pair of outer races having axial end surfaces opposing each other, the pair of inner races having axial end surfaces opposing each other, the pair of outer races fitted into and fixed to an outer member with the axial end surfaces thereof abutted to each other, and the pair of inner races fitted into and fixed to an inner member in the state where a desired preload is applied to the balls by pushing the pair of inner races with a gap between the axial end surfaces thereof to come closer to each other, wherein the axial center of the outer ring raceways is biased toward the side of the abutment of the outer races in the axial direction of the outer races, and wherein the retainer is of the crown type and comprises an annular main portion and a plurality of resilient portions provided on one axial side of the main portion such that a pocket is formed between a pair of circumferentially adjacent resilient portions, and wherein the main portion is provided closer to either axial end of the bearing device and wherein the outer races and inner races have an axial end surface on either axial side of the bearing device, such that the axial end surfaces of the outer races and inner races are placed at substantially the same location in the axial direction.
7. A bearing device comprising an outer race having an inner peripheral surface on which a pair of outer ring raceways are formed, a pair of inner races each having an outer peripheral surface on which an inner ring raceway is formed, a plurality of balls rotatably provided between the outer ring raceways and the inner ring raceways, a pair of retainers provided between the inner peripheral surface of the outer race and the outer peripheral surface of the inner races to rotatably hold the balls, the pair of inner races having axial end surfaces opposing each other, the outer race fitted into and fixed to an outer member, the pair of inner races fitted into and fixed to an inner member in the state where a desired preload is applied to the balls by pushing the pair of inner races with a gap between the axial end surfaces thereof to come closer to each other, wherein the axial center of the outer ring raceways is biased toward the center of the outer race in the axial direction of the outer race, and wherein the retainers are of the crown type and comprise an annular main portion and a plurality of resilient portions provided on one axial side of the main portion such that a pocket is formed between a pair of circumferentially adjacent resilient portions, and wherein the main portion is provided closer to either axial end of the bearing device and wherein the outer race and inner races have an axial end surface on either axial side of the bearing device, such that the axial end surfaces of the outer race and inner races are placed at substantially same location in the axial direction.
8. A bearing device comprising a pair of outer races each having an inner peripheral surface on which an outer ring raceway is formed, a pair of inner races each having an outer peripheral surface on which an inner ring raceway is formed, a plurality of balls rotatably provided between the outer ring raceway and the inner ring raceway, a cylindrical sleeve provided on the radially inside of the pair of inner rings, the pair of outer races having an axial end surface, respectively, such that the axial end surfaces are opposed to each other, the pair of inner races having an axial end surface, respectively, such that the axial end surfaces are opposed to each other, the axial end surfaces of the outer races abutted to each other, the pair of inner races fitted onto and fixed to the sleeve in the state where a desired preload is applied to the balls by pushing the pair of inner races with a gap between the axial end surfaces thereof to come closer to each other.
9. A bearing device comprising an outer race having an inner peripheral surface on which a pair of outer ring raceways are formed, a pair of inner races each having an outer peripheral surface on which an inner ring raceway is formed, a plurality of balls rotatably provided between the outer ring raceways and the inner ring raceways, a cylindrical sleeve provided on the radially inside of the pair of inner rings, the pair of inner races having an axial end surface, respectively, such that the axial end surfaces are opposed to each other, and the pair of inner races being fitted onto and fixed by the sleeve in the state where a desired preload is applied to the balls by pushing the inner races with a gap between the axial end surfaces thereof to come closer to each other.
10. A bearing device comprising a first and second outer races each having an inner peripheral surface on which an outer ring raceway is formed, a first and second inner races each having an outer peripheral surface on which an inner ring raceway is formed, a plurality of balls rotatably provided between the outer ring raceway and the inner ring raceway, the first and second outer races having an axial end surface, respectively, such that the axial end surfaces are opposed to each other, the first and second inner races having first and second axial end urfaces, respectively, such that the first axial end surfaces are opposed to each other, and the first and second outer races fitted into and fixed to an outer member with the first axial end surfaces abutted to each other, and the first and second inner races fitted into and fixed to an inner member in the state where a desired preload is applied to the balls by pushing the pair of inner races with a gap between the first axial end surfaces thereof to come closer to each other, the inner member having an outer peripheral surface on part of which an outward flange is formed, the outward flange having an axial side surface to which the second axial end surface of the first inner race is abutted for use, wherein the axial length of the inner peripheral surface of the second inner race is larger than the axial length of the inner peripheral surface of the first inner race.